ExperimentalResearchonthePerformanceofthe...
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Research Article ExperimentalResearchonthePerformanceofthe MacromoleculeColloidFire-ExtinguishingMaterialfor CoalSeamSpontaneousCombustion ShixingFan , 1,2 HuWen , 1,2 DuoZhang , 1,2 andZhijinYu 1,2 1 School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an, Shaanxi 710054, China 2 Key Laboratory of Mine and Disaster Prevention and Control of Ministry of Education, Xi’an University of Science and Technology, Xi’an, Shaanxi 710054, China Correspondence should be addressed to Hu Wen; [email protected] Received 29 March 2019; Accepted 22 July 2019; Published 15 August 2019 Academic Editor: Zhonghua Yao Copyright © 2019 Shixing Fan et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Coal resources are rich in China. ey are mainly concentrated in the northwest region. But these resources also make the situation of spontaneous coal combustion hazards most serious in this area. Affected by the arid and semiarid climate, the water resource in this area is relatively scarce. In order to improve the utilization rate of water, a macromolecule colloid for coal mine fire fighting was developed in this research. e main components of the macromolecule colloid and the principle of gel formation were analyzed. e physical and chemical properties of the macromolecule colloid were analyzed by the time of gelation and the water loss. e water content of the macromolecule colloid was as high as 99%. e inhibition performance of the macromolecule colloid on coal fire was studied by the programmed heating device. e experimental results show that the macromolecule colloid has a significant inhibitory effect on the heating rate, oxygen consumption rate, and gas production rate. It inhibits the coal- oxygen composite by increasing the activation energy (E a ) of coal, which also has the effect of wrapping coal to isolate oxygen. e inhibition performance of the macromolecule colloid on coal fire disasters is better than that of water, water glass, loess compound colloids, and other traditional fire-extinguishing materials. 1.Introduction e spontaneous combustion of coal in underground longwall gob areas represents a significant hazard associated with the coal industry in the world [1]. is phenomenon can affect mine production such that major economic losses incur and also may lead to gas explosions with the potential for heavy casualties. Ellyett and Fleming believe that Aus- tralia’s Burning Mountain coal field has been burning for more than 6,000years. Since the era of Herodotus, Tajiki- stan’s Ravat coal field fire has been burning for more than 2,000 years [2]. In coal-producing countries, especially in China [3–6], the United States [7–9], Australia [1, 10, 11], India [12–14], South Africa [15, 16], and so on, the coal field fire is more serious. Coal fire disaster not only burns a lot of coal resources directly, which threatens the safety of miners and results in large economic losses [17], but also seriously endangers the ecological environment (for example, air pollution, surface heat disasters, and groundwater pollution). In order to control coal fire disasters, researchers in various countries have developed a variety of fire-fighting technologies such as water injection [18, 19], stripping [3], grouting (yellow mud slurry, fly ash slurry, and cement slurry) [20], three-phase foam perfusion [21], multiphase foam [22], composite gel (loess compound colloids and fly ash composite colloids) [23, 24], and ionic liquids [25]. ese methods have achieved tangible results in controlling coal fires but also have some shortcomings. For example, the flow of water will increase the porosity of the coal, and the air will flow more easily into the void after evaporation. An ex- plosion accident occurs easily when water encounters a Hindawi Advances in Materials Science and Engineering Volume 2019, Article ID 6940985, 10 pages https://doi.org/10.1155/2019/6940985
Transcript of ExperimentalResearchonthePerformanceofthe...
Research ArticleExperimental Research on the Performance of theMacromolecule Colloid Fire-Extinguishing Material forCoal Seam Spontaneous Combustion
Shixing Fan 12 Hu Wen 12 Duo Zhang 12 and Zhijin Yu 12
1School of Safety Science and Engineering Xirsquoan University of Science and Technology Xirsquoan Shaanxi 710054 China2Key Laboratory of Mine and Disaster Prevention and Control of Ministry of EducationXirsquoan University of Science and Technology Xirsquoan Shaanxi 710054 China
Correspondence should be addressed to Hu Wen wenhxusteducn
Received 29 March 2019 Accepted 22 July 2019 Published 15 August 2019
Academic Editor Zhonghua Yao
Copyright copy 2019 Shixing Fan et al +is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
Coal resources are rich in China +ey are mainly concentrated in the northwest region But these resources also make thesituation of spontaneous coal combustion hazards most serious in this area Affected by the arid and semiarid climate the waterresource in this area is relatively scarce In order to improve the utilization rate of water a macromolecule colloid for coal mine firefighting was developed in this research +e main components of the macromolecule colloid and the principle of gel formationwere analyzed +e physical and chemical properties of the macromolecule colloid were analyzed by the time of gelation and thewater loss +e water content of the macromolecule colloid was as high as 99+e inhibition performance of the macromoleculecolloid on coal fire was studied by the programmed heating device +e experimental results show that the macromolecule colloidhas a significant inhibitory effect on the heating rate oxygen consumption rate and gas production rate It inhibits the coal-oxygen composite by increasing the activation energy (Ea) of coal which also has the effect of wrapping coal to isolate oxygen+einhibition performance of the macromolecule colloid on coal fire disasters is better than that of water water glass loess compoundcolloids and other traditional fire-extinguishing materials
1 Introduction
+e spontaneous combustion of coal in undergroundlongwall gob areas represents a significant hazard associatedwith the coal industry in the world [1] +is phenomenoncan affect mine production such that major economic lossesincur and also may lead to gas explosions with the potentialfor heavy casualties Ellyett and Fleming believe that Aus-traliarsquos Burning Mountain coal field has been burning formore than 6000 years Since the era of Herodotus Tajiki-stanrsquos Ravat coal field fire has been burning for more than2000 years [2] In coal-producing countries especially inChina [3ndash6] the United States [7ndash9] Australia [1 10 11]India [12ndash14] South Africa [15 16] and so on the coal fieldfire is more serious Coal fire disaster not only burns a lot ofcoal resources directly which threatens the safety of miners
and results in large economic losses [17] but also seriouslyendangers the ecological environment (for example airpollution surface heat disasters and groundwaterpollution)
In order to control coal fire disasters researchers invarious countries have developed a variety of fire-fightingtechnologies such as water injection [18 19] stripping [3]grouting (yellow mud slurry fly ash slurry and cementslurry) [20] three-phase foam perfusion [21] multiphasefoam [22] composite gel (loess compound colloids and flyash composite colloids) [23 24] and ionic liquids [25]+esemethods have achieved tangible results in controlling coalfires but also have some shortcomings For example the flowof water will increase the porosity of the coal and the air willflow more easily into the void after evaporation An ex-plosion accident occurs easily when water encounters a
HindawiAdvances in Materials Science and EngineeringVolume 2019 Article ID 6940985 10 pageshttpsdoiorg10115520196940985
high-temperature coal fire area (as shown in Figure 1) It willcause secondary disasters For the higher position of the coalfield fire the effect of grouting technology is not good be-cause of its limited spreading range +e instability of thefoam limits the performance of the three-phase foam and themultiphase foam Water glass can be easily dehydrated andshrinked finally into powder +e cost of using the com-posite gel technology for fire fighting is very high in areaswhere there is lack of loess and fly ash
Coal resources are mainly distributed in the western andnorthern regions of China As shown in Figure 2 the coalproduction of six provinces (autonomous regions) whichare Shanxi Shaanxi Inner Mongolia Ningxia Gansu andXinjiang accounted for 7869 of the national coal pro-duction +e above areas are typical of arid or semiaridclimate with less water and serious desertification Becauseof the thick coal seam burial shallow serious abuse andother factors the coal fire disaster in these regions is moreserious [26] +e direct combustion of coal quantity eachyear due to coal fire is 20million tons In 2010 the coal fire ofChina has been included in the ldquofive global sustainableecological disastersrdquo by ldquoForeign Policyrdquo [27]
In order to effectively control the coal fire disasterimprove the utilization of water and overcome the short-comings of traditional fire-fighting methods this paperprovides a macromolecular gel colloid for controlling thespontaneous combustion of coal in coal mines
2 Macromolecular Colloid and ItsMechanism of Inhibiting Coal Oxidation
21 Macromolecular Colloid Composition and GellingPrinciple +e macromolecular materials in this study wereprovided by Xirsquoan TianheMining Technology Co Ltd+eirmain components are linear polymer materials and tran-sition-metal high-valent ion solutions such as copolymers ofacrylic acid vinyl acetate and solution containing Al3+ Inorder to master the main components and structure ofmacromolecular colloids a SpectrumOne Fourier transforminfrared spectrometer was used to analyze them as shown inFigure 3 According to the position analysis of the ab-sorption peak in Figure 3 the main contents of the mac-romolecular colloid are Mg2+ Ca2+ AlO2minus COO n
CH2O n and so onWhen the macromolecular material encounters water
swelling occurs which causes a large amount of water to becontrolled within the macromolecular colloid Since thematerial has some crosslinking bonds it could not be dissolvedand eventually form gel clumps Macromolecular colloids aremainly composed of organic and inorganic componentsOrganic components are mainly a mesh structure and part ofthe molecular formula is shown in Figure 4
22 Mechanism of Inhibiting Coal Oxidation +e oxidationstarts from the surface of the coal+e first step is the contactof coal and oxygen in which physical adsorption occursfollowed by the chemical adsorption and chemical reactionwhich release heat +e process of chemical reaction also
produces a large number of active groups and free radicals sothat the chemical reaction continues +e fire suppression ofmacromolecular colloids is to suppress all aspects of coal-oxygen composites thus effectively reducing the heat gen-eration and releasing heat accumulated in the coal
221 Reduction of Physical Adsorption +e macromolec-ular colloid can wet the coal surface and turn the gas-solidinterface into the liquid-solid interface +erefore themacromolecular colloids isolate coal and oxygen whichreduce or prevent the physical adsorption of coal on oxygen
222 Prevention of Chemical Adsorption and ChemicalReactions +e process of coal-oxygen chemical adsorptionis that the electron cloud in the coal enters the two unpairedelectron orbitals of the oxygen molecules and the electroncloud is covered to produce the π complex and the σcomplex meanwhile the adsorption heat is released +ereaction process is shown in Figure 5
Macromolecular colloids contain a variety of ions andmolecules some of which are electrophilic reagents +eelectrophilic reagent is usually located on the colloidal net-work It can adsorb with the active structure of coal and evenproduce complex compounds However its complex can nolonger undergo electrophilic substitution or oxidation witharomatic rings Moreover the function of the colloid and theactive structure stop in the first step +e second step is slow+e product is predominantly a π complex and the amount ofσ complexes is very small +e process produces little heat+e reaction process is shown in Figure 6
3 Study on Physical Properties ofMacromolecular Materials
31 Gel Time of the Macromolecular Materials +e prepa-ration of different concentrations of macromolecular col-loids is shown in Table 1 First the macromolecular materialand water are weighed and then the macromolecular ma-terial is poured into the water andmixed continuously with aglass rod +e gelling time is measured by using a stopwatchand the results are shown in Figure 7 It can be seen thatwhen the concentration is a few thousandths they can begelled smoothly It shows that the water absorption propertyof the macromolecular material is stronger At 20degC thegelling time of the macromolecular material decreases withthe increase of the concentration
+e ratio of the macromolecular material to water wasset at 10 to prepare a macromolecular colloid +e ex-perimental temperature was adjusted by the HH-M6 digitalwater bath and the temperature was controlled at 20degC40degC 60degC 80degC and 100degC respectively +e macromo-lecular material which was weighed was slowly added to thewater and stirred continuously with a glass rod +e gel timewas measured with a stopwatch +e results are shown inFigure 8 +e time of gelation of macromolecular fire-extinguishing materials is greatly affected by temperature+e gel time is almost linearly decreasing with increasingtemperature After 45degC the gel time is reduced to lessthan 10 s
2 Advances in Materials Science and Engineering
32 Viscosity of the Macromolecular Materials Figure 9shows the plots of viscosity versus time for the macromo-lecular materials at different concentrations For each
concentration the viscosity of macromolecular materialsdecreases rapidly within 30mins and then the rate of thedecline is gradually decreased Approximately 250 hourslater the viscosity increased slightly because of the increaseof concentration of the macromolecular materials caused bythe loss of water Subsequently the above-mentioned
T (
)
20
40
60
80
100
120
3500 3000 2500 2000 1500 1000 5004000Wavenumber (cmndash1)
Figure 3 Infrared spectra of macromolecular gel colloids
CH2 CH
C
O
O
CO
CH2
Fe2+
CH
C COONa
COONa
O
O
C O
CH2 CH
CH2 CH CH2 CH CH2 CH
Figure 4 Partial molecular formula of macromolecular colloids
Figure 1 An explosion caused by water injection (high-pressure water column)
Xinjiang
Ningxia
Shanxi
Shaanxi
Inner MongoliaGansuOthers
Xinjiang
Ningxia
Inner Mongolia
Beijing
2458129
2131
199
2179
464244
Shanxi
Shaanxi
Gansu
Figure 2 Major coal-producing areas in China
Advances in Materials Science and Engineering 3
reciprocating trend occurs continuously until the content ofwater is small and the surface is dry In addition the viscosityof the macromolecular materials increases with the increaseof the concentration When the concentration increases to12 the initial viscosity of the macromolecular materialincreases significantly which is about ten times higher than10 Under such conditions because of its large flow re-sistance it is difficult to transport the colloid to the desiredself-ignition area further affecting the fire-prevention effect
33 Rate of Water Loss Macromolecular colloid is a highwater-retaining material and about 99 of its compositionis water +e water retention of macromolecular colloids is akey factor in fire fighting+erefore according to the changeof the mass of the colloid the average water loss per unittime is measured +e experimental environment temper-ature is 20degC +e colloidal concentrations of the macro-molecular colloid were 04 06 08 10 12 and
14 respectively As shown in Figure 10 it can be seen thatthe six curves are substantially coincident With the increaseof time the average water loss decreases first and when it
CH2 +O2
O2H2C
H2C
HC
OOHOO
Figure 5 Chemical adsorption and chemical reaction processes
CH2 +E+
E+
H2C 21
H2C OO
HC
E
Figure 6 Prevention of chemical adsorption and chemical reaction processes by colloids
Table 1 Preparation of colloids with different concentrationsWater (g) 2988 2982 2976 297 2964 2958Macromolecular colloid(g) 12 18 24 30 36 42
Concentration () 04 06 08 10 12 14
Gel
time (
s)
0
20
40
60
80
100
06 08 10 12 1404Concentration ()
Figure 7 Change curve of gel time with concentration
Gel
time (
s)
40 60 80 10020Temperature (degC)
0
4
8
12
16
Figure 8 Change curve of gel time with temperature
040608
101214
Visc
osity
(Pamiddots
)
1 2 3 200 400 6000Time (h)
0
20000
40000
600000
1200000
1800000
Figure 9 Effects of concentration on the viscosity of macromo-lecular colloids
4 Advances in Materials Science and Engineering
reaches a certain threshold it starts to increase and thendecrease +is shows that colloidal concentration has littleeffect on the rate of water loss
A macromolecular colloid with a concentration of 1was prepared +e macromolecular colloids were placed in awater bath at different temperatures (20degC 40degC 60degC 80degCand 100degC) And then the changes of the mass of themacromolecular colloid with time were measured +e re-sults are shown in Figure 11 It can be seen that the averagewater loss rate of the macromolecular colloid increases withincreasing temperature +e average water loss rate for eachtemperature condition has a maximum value +e peakswere 057 gh 147 gh 399 gh 734 gh and 1049 ghrespectively
4 Study on Fire-Fighting Performance ofMacromolecular Colloids
41 Experimental Equipment and Process In this paper aself-designed temperature-programmed experimental sys-tem was used to test the performance of the macromolecularcolloid +e experimental system is shown in Figure 12(a)[28] +e system mainly includes four process gas supplytemperature control gas analysis and tail gas treatment+eloading capacity of the self-made coal sample tank is 1000 gand the structure is shown in Figure 12(b)
+e selected coal samples were mixed with water waterglass colloid (WGC) loess compound colloid (LCC) fly ashcomposite colloid (FACC) and macromolecular colloid(MC) (as shown in Table 2) then soaked for 12 hours andfinally placed on a 05mm wire mesh After no waterdropping they were loaded into a coal sample tank to beginthe experiment Water glass and gelling agents are fromXirsquoan Tianhe Mining Technology Co Ltd
+e treated coal sample was charged into an experi-mental furnace and nitrogen gas was introduced for
30minutes+en the air was allowed and the flow was set to120mlmin+e experiment started from 25degC to 170degC andthe heating rate was 20degCh When the temperature of thecoal sample was higher than 10degC the gas in the coal sampletank was analyzed by gas chromatography
42 Results and Discussion +e experiment was carried outin the Key Laboratory of Mine and Disaster Prevention andControl of Ministry of Education +e ambient temperaturewas 200ndash250degC the relative humidity was 580ndash700 andthe atmospheric pressure was about 1010 kPa
421 Effects of Macromolecular Colloids on Heating Rate+e study of Xu et al [29] showed that the temperature-programmed experimental method is a technique for short-term testing of spontaneous coal combustion Spontaneouscoal oxidation combustion is a dynamic process of nonlineardevelopment [30 31]
It can be seen from Figure 13 that the coal temperatureincreases gradually [32] and the heating process is dividedinto three stages (I lt90degC II 90ndash100degC and III gt100degC)+e resistance effect of various fire-prevention materials ismainly reflected in stage II From 90degC to 100degC each coalsample (No 1 No 2 No 3 No 4 No 5 and No 6) requires48min 55min 826min 373min 550min and 921minrespectively +is shows that the resistance effect of themacromolecular colloid is significantly better than that ofother fire-prevention materials
422 Effects of Macromolecular Colloids on Oxygen Con-sumption Rate As can be seen from Figure 14 the oxygenconsumption rate of coal samples (No 1 No 2 No 3 No 4No 5 and No 6) increased with increasing temperature[33] +e oxygen consumption rate of the raw coal (No 1)was greater than the oxygen consumption rate of the treated
040608
101214
Wat
er lo
ss (g
middothndash1
)
005
010
015
020
025
030
035
100 200 300 400 5000Time (h)
Figure 10 Effects of concentration on the water loss of macro-molecular colloids
20degC40degC60degC
80degC100degC
Wat
er lo
ss (g
middothndash1
)
0 10 20 30 100 200 300 400 500Time (h)
0
2
4
6
8
10
Figure 11 Effects of temperature on the water loss of macro-molecular colloids
Advances in Materials Science and Engineering 5
coal samples (No 2 No 3 No 4 No 5 and No 6) Whenthe coal sample temperature was below 60degC the differencein the rate of heating of various coal samples was small After80degC the heating rate of the coal sample treated with themacromolecular colloid (No 6) was significantly smallerthan that of other coal samples (No 1 No 2 No 3 No 4and No 5)
423 Effects of Macromolecular Colloids on CO Dou et al[34] Xu et al [29] and Deng et al [28] studies showed thatthe emission of CO has a significant dependence on tem-perature So CO has been considered as an effective meansof tracking or predicting coal spontaneous combustionAccordingly we studied the CO concentration of the rawcoal sample and the treated coal sample at various tem-peratures +e results are shown in Figure 15
As can be seen from Figure 15 the amount of COproduced by the treated coal samples (No 2 No 3 No 4No 5 and No 6) was much lower than the amount of COproduced by the raw coal sample (No 1) and among themNo 6 produced the smallest +is shows that the macro-molecular colloid effectively inhibits the oxidation process ofcoal
424 Effects of Macromolecular Colloids on Activation En-ergy (Ea) According to the kinetic theory of reaction the Eain each reaction was different +e lower the Ea is the easierthe reaction is and the faster the reaction rate is +ereforeEa could be used as an indicator of spontaneous coalcombustion propensity [35]
According to the literature [30] the reaction process ofcoal oxidation and temperature rising can be described as
Coal + O2⟶ aCO + bCO2 + others (1)
According to Arrheniusrsquo law the rate of oxidation at anycoal temperature is shown as
Automatic airsource pump
Flow meter
Thermocouplethermometer Programmed heating box Sink Gas chromatograph
(a)
Outlet
Thermocouple
Steel container
Coal sampley
xInlet
(b)
Figure 12 Temperature-programmed experiment of spontaneous coal combustion
Table 2 Treatment of the coal samples
Number Sample Remarks Quantity1 Raw coal Nothing Nothing2 Coal +water Water 2 kg3 Coal +WGC Na2SiO3middot9H2O concentration of 10
NaHCO3 concentration of 4 2 kg
4 Coal + LCC Water-soil ratio is 1 1 and gelling agent added is01 2 kg
5 Coal + FACC Water-fly ash ratio is 1 1 and gelling agent added is01 2 kg
6 Coal +MC Water-macromolecular material ratio is 99 1 2 kg+e proportions are quantity ratios
No 1
No 3No 5No 2No 4
No 6
I
II
III
Tem
pera
ture
(degC)
200 400 600 800 1000 1200 1400 16000Time (min)
0
20
40
60
80
100
120
140
160
180
Figure 13 Law of the change of coal sample temperature with time
6 Advances in Materials Science and Engineering
r Tk( 1113857 r O2( 1113857 r(CO)
a r
CO2( 1113857
b k0C
mO2
expminus Ea
RTk1113888 1113889
(2)
where r(α) is the reaction rate (mol(m3middots)) Tk is thetemperature of coal (degC) a and b are coefficients k0 is theexponential factor CO2
is the molecular strength of oxygenin air (molm3) m is the reaction series Ea denotes theactivity energy (kJmol) and R is the gas constant (8314 J(degCmiddotmol))
During the experiment it is assumed that the air flowsalong the longitudinal direction of the coal sample tank that
is the positive direction of y as shown in Figure 12(b) +erate of CO generation at any point in the y direction is
dVco S middot ak0Cm
O2exp minus EaRT( 1113857
k middot vairdy (3)
where Vco is the CO concentration (ppm) S is the sectionalarea of the coal sample tank (m2) vair is the airflow velocity(m3s) and k is the concentration conversion coefficient(224times109)
Integrating the above formula (3) we obtain
1113946Pout
Pin
dVco 1113946L
0
S middot ak0CmO2
exp minus EaRT( 1113857
k middot vairdy (4)
No 1No 2No 3
No 4No 5No 6
O2 (
)
3
6
9
12
15
18
21
40 60 80 100 120 140 160 180 20020Temperatrue (degC)
(a)
No 1No 2No 3
No 4No 5No 6
Oxy
gen
cons
umpt
ion
rate
(10ndash1
1 m
olmiddotcm
ndash3middotsndash1
)
40 60 80 100 120 140 160 180 20020Temperature (degC)
0200400600800
100012001400160018002000
(b)
Figure 14 Oxygen consumption rate at different temperatures
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
0
1000
2000
3000
4000
5000
6000
7000
8000
Con
cent
ratio
n of
CO
(ppm
)
(a)
0
10
20
30
40
50
60
70
Rate
of C
O p
rodu
ctio
n (1
011 m
ol(
cm3 times
s))
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
(b)
Figure 15 Curves of the CO production rate of coal samples
Advances in Materials Science and Engineering 7
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
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Submit your manuscripts atwwwhindawicom
high-temperature coal fire area (as shown in Figure 1) It willcause secondary disasters For the higher position of the coalfield fire the effect of grouting technology is not good be-cause of its limited spreading range +e instability of thefoam limits the performance of the three-phase foam and themultiphase foam Water glass can be easily dehydrated andshrinked finally into powder +e cost of using the com-posite gel technology for fire fighting is very high in areaswhere there is lack of loess and fly ash
Coal resources are mainly distributed in the western andnorthern regions of China As shown in Figure 2 the coalproduction of six provinces (autonomous regions) whichare Shanxi Shaanxi Inner Mongolia Ningxia Gansu andXinjiang accounted for 7869 of the national coal pro-duction +e above areas are typical of arid or semiaridclimate with less water and serious desertification Becauseof the thick coal seam burial shallow serious abuse andother factors the coal fire disaster in these regions is moreserious [26] +e direct combustion of coal quantity eachyear due to coal fire is 20million tons In 2010 the coal fire ofChina has been included in the ldquofive global sustainableecological disastersrdquo by ldquoForeign Policyrdquo [27]
In order to effectively control the coal fire disasterimprove the utilization of water and overcome the short-comings of traditional fire-fighting methods this paperprovides a macromolecular gel colloid for controlling thespontaneous combustion of coal in coal mines
2 Macromolecular Colloid and ItsMechanism of Inhibiting Coal Oxidation
21 Macromolecular Colloid Composition and GellingPrinciple +e macromolecular materials in this study wereprovided by Xirsquoan TianheMining Technology Co Ltd+eirmain components are linear polymer materials and tran-sition-metal high-valent ion solutions such as copolymers ofacrylic acid vinyl acetate and solution containing Al3+ Inorder to master the main components and structure ofmacromolecular colloids a SpectrumOne Fourier transforminfrared spectrometer was used to analyze them as shown inFigure 3 According to the position analysis of the ab-sorption peak in Figure 3 the main contents of the mac-romolecular colloid are Mg2+ Ca2+ AlO2minus COO n
CH2O n and so onWhen the macromolecular material encounters water
swelling occurs which causes a large amount of water to becontrolled within the macromolecular colloid Since thematerial has some crosslinking bonds it could not be dissolvedand eventually form gel clumps Macromolecular colloids aremainly composed of organic and inorganic componentsOrganic components are mainly a mesh structure and part ofthe molecular formula is shown in Figure 4
22 Mechanism of Inhibiting Coal Oxidation +e oxidationstarts from the surface of the coal+e first step is the contactof coal and oxygen in which physical adsorption occursfollowed by the chemical adsorption and chemical reactionwhich release heat +e process of chemical reaction also
produces a large number of active groups and free radicals sothat the chemical reaction continues +e fire suppression ofmacromolecular colloids is to suppress all aspects of coal-oxygen composites thus effectively reducing the heat gen-eration and releasing heat accumulated in the coal
221 Reduction of Physical Adsorption +e macromolec-ular colloid can wet the coal surface and turn the gas-solidinterface into the liquid-solid interface +erefore themacromolecular colloids isolate coal and oxygen whichreduce or prevent the physical adsorption of coal on oxygen
222 Prevention of Chemical Adsorption and ChemicalReactions +e process of coal-oxygen chemical adsorptionis that the electron cloud in the coal enters the two unpairedelectron orbitals of the oxygen molecules and the electroncloud is covered to produce the π complex and the σcomplex meanwhile the adsorption heat is released +ereaction process is shown in Figure 5
Macromolecular colloids contain a variety of ions andmolecules some of which are electrophilic reagents +eelectrophilic reagent is usually located on the colloidal net-work It can adsorb with the active structure of coal and evenproduce complex compounds However its complex can nolonger undergo electrophilic substitution or oxidation witharomatic rings Moreover the function of the colloid and theactive structure stop in the first step +e second step is slow+e product is predominantly a π complex and the amount ofσ complexes is very small +e process produces little heat+e reaction process is shown in Figure 6
3 Study on Physical Properties ofMacromolecular Materials
31 Gel Time of the Macromolecular Materials +e prepa-ration of different concentrations of macromolecular col-loids is shown in Table 1 First the macromolecular materialand water are weighed and then the macromolecular ma-terial is poured into the water andmixed continuously with aglass rod +e gelling time is measured by using a stopwatchand the results are shown in Figure 7 It can be seen thatwhen the concentration is a few thousandths they can begelled smoothly It shows that the water absorption propertyof the macromolecular material is stronger At 20degC thegelling time of the macromolecular material decreases withthe increase of the concentration
+e ratio of the macromolecular material to water wasset at 10 to prepare a macromolecular colloid +e ex-perimental temperature was adjusted by the HH-M6 digitalwater bath and the temperature was controlled at 20degC40degC 60degC 80degC and 100degC respectively +e macromo-lecular material which was weighed was slowly added to thewater and stirred continuously with a glass rod +e gel timewas measured with a stopwatch +e results are shown inFigure 8 +e time of gelation of macromolecular fire-extinguishing materials is greatly affected by temperature+e gel time is almost linearly decreasing with increasingtemperature After 45degC the gel time is reduced to lessthan 10 s
2 Advances in Materials Science and Engineering
32 Viscosity of the Macromolecular Materials Figure 9shows the plots of viscosity versus time for the macromo-lecular materials at different concentrations For each
concentration the viscosity of macromolecular materialsdecreases rapidly within 30mins and then the rate of thedecline is gradually decreased Approximately 250 hourslater the viscosity increased slightly because of the increaseof concentration of the macromolecular materials caused bythe loss of water Subsequently the above-mentioned
T (
)
20
40
60
80
100
120
3500 3000 2500 2000 1500 1000 5004000Wavenumber (cmndash1)
Figure 3 Infrared spectra of macromolecular gel colloids
CH2 CH
C
O
O
CO
CH2
Fe2+
CH
C COONa
COONa
O
O
C O
CH2 CH
CH2 CH CH2 CH CH2 CH
Figure 4 Partial molecular formula of macromolecular colloids
Figure 1 An explosion caused by water injection (high-pressure water column)
Xinjiang
Ningxia
Shanxi
Shaanxi
Inner MongoliaGansuOthers
Xinjiang
Ningxia
Inner Mongolia
Beijing
2458129
2131
199
2179
464244
Shanxi
Shaanxi
Gansu
Figure 2 Major coal-producing areas in China
Advances in Materials Science and Engineering 3
reciprocating trend occurs continuously until the content ofwater is small and the surface is dry In addition the viscosityof the macromolecular materials increases with the increaseof the concentration When the concentration increases to12 the initial viscosity of the macromolecular materialincreases significantly which is about ten times higher than10 Under such conditions because of its large flow re-sistance it is difficult to transport the colloid to the desiredself-ignition area further affecting the fire-prevention effect
33 Rate of Water Loss Macromolecular colloid is a highwater-retaining material and about 99 of its compositionis water +e water retention of macromolecular colloids is akey factor in fire fighting+erefore according to the changeof the mass of the colloid the average water loss per unittime is measured +e experimental environment temper-ature is 20degC +e colloidal concentrations of the macro-molecular colloid were 04 06 08 10 12 and
14 respectively As shown in Figure 10 it can be seen thatthe six curves are substantially coincident With the increaseof time the average water loss decreases first and when it
CH2 +O2
O2H2C
H2C
HC
OOHOO
Figure 5 Chemical adsorption and chemical reaction processes
CH2 +E+
E+
H2C 21
H2C OO
HC
E
Figure 6 Prevention of chemical adsorption and chemical reaction processes by colloids
Table 1 Preparation of colloids with different concentrationsWater (g) 2988 2982 2976 297 2964 2958Macromolecular colloid(g) 12 18 24 30 36 42
Concentration () 04 06 08 10 12 14
Gel
time (
s)
0
20
40
60
80
100
06 08 10 12 1404Concentration ()
Figure 7 Change curve of gel time with concentration
Gel
time (
s)
40 60 80 10020Temperature (degC)
0
4
8
12
16
Figure 8 Change curve of gel time with temperature
040608
101214
Visc
osity
(Pamiddots
)
1 2 3 200 400 6000Time (h)
0
20000
40000
600000
1200000
1800000
Figure 9 Effects of concentration on the viscosity of macromo-lecular colloids
4 Advances in Materials Science and Engineering
reaches a certain threshold it starts to increase and thendecrease +is shows that colloidal concentration has littleeffect on the rate of water loss
A macromolecular colloid with a concentration of 1was prepared +e macromolecular colloids were placed in awater bath at different temperatures (20degC 40degC 60degC 80degCand 100degC) And then the changes of the mass of themacromolecular colloid with time were measured +e re-sults are shown in Figure 11 It can be seen that the averagewater loss rate of the macromolecular colloid increases withincreasing temperature +e average water loss rate for eachtemperature condition has a maximum value +e peakswere 057 gh 147 gh 399 gh 734 gh and 1049 ghrespectively
4 Study on Fire-Fighting Performance ofMacromolecular Colloids
41 Experimental Equipment and Process In this paper aself-designed temperature-programmed experimental sys-tem was used to test the performance of the macromolecularcolloid +e experimental system is shown in Figure 12(a)[28] +e system mainly includes four process gas supplytemperature control gas analysis and tail gas treatment+eloading capacity of the self-made coal sample tank is 1000 gand the structure is shown in Figure 12(b)
+e selected coal samples were mixed with water waterglass colloid (WGC) loess compound colloid (LCC) fly ashcomposite colloid (FACC) and macromolecular colloid(MC) (as shown in Table 2) then soaked for 12 hours andfinally placed on a 05mm wire mesh After no waterdropping they were loaded into a coal sample tank to beginthe experiment Water glass and gelling agents are fromXirsquoan Tianhe Mining Technology Co Ltd
+e treated coal sample was charged into an experi-mental furnace and nitrogen gas was introduced for
30minutes+en the air was allowed and the flow was set to120mlmin+e experiment started from 25degC to 170degC andthe heating rate was 20degCh When the temperature of thecoal sample was higher than 10degC the gas in the coal sampletank was analyzed by gas chromatography
42 Results and Discussion +e experiment was carried outin the Key Laboratory of Mine and Disaster Prevention andControl of Ministry of Education +e ambient temperaturewas 200ndash250degC the relative humidity was 580ndash700 andthe atmospheric pressure was about 1010 kPa
421 Effects of Macromolecular Colloids on Heating Rate+e study of Xu et al [29] showed that the temperature-programmed experimental method is a technique for short-term testing of spontaneous coal combustion Spontaneouscoal oxidation combustion is a dynamic process of nonlineardevelopment [30 31]
It can be seen from Figure 13 that the coal temperatureincreases gradually [32] and the heating process is dividedinto three stages (I lt90degC II 90ndash100degC and III gt100degC)+e resistance effect of various fire-prevention materials ismainly reflected in stage II From 90degC to 100degC each coalsample (No 1 No 2 No 3 No 4 No 5 and No 6) requires48min 55min 826min 373min 550min and 921minrespectively +is shows that the resistance effect of themacromolecular colloid is significantly better than that ofother fire-prevention materials
422 Effects of Macromolecular Colloids on Oxygen Con-sumption Rate As can be seen from Figure 14 the oxygenconsumption rate of coal samples (No 1 No 2 No 3 No 4No 5 and No 6) increased with increasing temperature[33] +e oxygen consumption rate of the raw coal (No 1)was greater than the oxygen consumption rate of the treated
040608
101214
Wat
er lo
ss (g
middothndash1
)
005
010
015
020
025
030
035
100 200 300 400 5000Time (h)
Figure 10 Effects of concentration on the water loss of macro-molecular colloids
20degC40degC60degC
80degC100degC
Wat
er lo
ss (g
middothndash1
)
0 10 20 30 100 200 300 400 500Time (h)
0
2
4
6
8
10
Figure 11 Effects of temperature on the water loss of macro-molecular colloids
Advances in Materials Science and Engineering 5
coal samples (No 2 No 3 No 4 No 5 and No 6) Whenthe coal sample temperature was below 60degC the differencein the rate of heating of various coal samples was small After80degC the heating rate of the coal sample treated with themacromolecular colloid (No 6) was significantly smallerthan that of other coal samples (No 1 No 2 No 3 No 4and No 5)
423 Effects of Macromolecular Colloids on CO Dou et al[34] Xu et al [29] and Deng et al [28] studies showed thatthe emission of CO has a significant dependence on tem-perature So CO has been considered as an effective meansof tracking or predicting coal spontaneous combustionAccordingly we studied the CO concentration of the rawcoal sample and the treated coal sample at various tem-peratures +e results are shown in Figure 15
As can be seen from Figure 15 the amount of COproduced by the treated coal samples (No 2 No 3 No 4No 5 and No 6) was much lower than the amount of COproduced by the raw coal sample (No 1) and among themNo 6 produced the smallest +is shows that the macro-molecular colloid effectively inhibits the oxidation process ofcoal
424 Effects of Macromolecular Colloids on Activation En-ergy (Ea) According to the kinetic theory of reaction the Eain each reaction was different +e lower the Ea is the easierthe reaction is and the faster the reaction rate is +ereforeEa could be used as an indicator of spontaneous coalcombustion propensity [35]
According to the literature [30] the reaction process ofcoal oxidation and temperature rising can be described as
Coal + O2⟶ aCO + bCO2 + others (1)
According to Arrheniusrsquo law the rate of oxidation at anycoal temperature is shown as
Automatic airsource pump
Flow meter
Thermocouplethermometer Programmed heating box Sink Gas chromatograph
(a)
Outlet
Thermocouple
Steel container
Coal sampley
xInlet
(b)
Figure 12 Temperature-programmed experiment of spontaneous coal combustion
Table 2 Treatment of the coal samples
Number Sample Remarks Quantity1 Raw coal Nothing Nothing2 Coal +water Water 2 kg3 Coal +WGC Na2SiO3middot9H2O concentration of 10
NaHCO3 concentration of 4 2 kg
4 Coal + LCC Water-soil ratio is 1 1 and gelling agent added is01 2 kg
5 Coal + FACC Water-fly ash ratio is 1 1 and gelling agent added is01 2 kg
6 Coal +MC Water-macromolecular material ratio is 99 1 2 kg+e proportions are quantity ratios
No 1
No 3No 5No 2No 4
No 6
I
II
III
Tem
pera
ture
(degC)
200 400 600 800 1000 1200 1400 16000Time (min)
0
20
40
60
80
100
120
140
160
180
Figure 13 Law of the change of coal sample temperature with time
6 Advances in Materials Science and Engineering
r Tk( 1113857 r O2( 1113857 r(CO)
a r
CO2( 1113857
b k0C
mO2
expminus Ea
RTk1113888 1113889
(2)
where r(α) is the reaction rate (mol(m3middots)) Tk is thetemperature of coal (degC) a and b are coefficients k0 is theexponential factor CO2
is the molecular strength of oxygenin air (molm3) m is the reaction series Ea denotes theactivity energy (kJmol) and R is the gas constant (8314 J(degCmiddotmol))
During the experiment it is assumed that the air flowsalong the longitudinal direction of the coal sample tank that
is the positive direction of y as shown in Figure 12(b) +erate of CO generation at any point in the y direction is
dVco S middot ak0Cm
O2exp minus EaRT( 1113857
k middot vairdy (3)
where Vco is the CO concentration (ppm) S is the sectionalarea of the coal sample tank (m2) vair is the airflow velocity(m3s) and k is the concentration conversion coefficient(224times109)
Integrating the above formula (3) we obtain
1113946Pout
Pin
dVco 1113946L
0
S middot ak0CmO2
exp minus EaRT( 1113857
k middot vairdy (4)
No 1No 2No 3
No 4No 5No 6
O2 (
)
3
6
9
12
15
18
21
40 60 80 100 120 140 160 180 20020Temperatrue (degC)
(a)
No 1No 2No 3
No 4No 5No 6
Oxy
gen
cons
umpt
ion
rate
(10ndash1
1 m
olmiddotcm
ndash3middotsndash1
)
40 60 80 100 120 140 160 180 20020Temperature (degC)
0200400600800
100012001400160018002000
(b)
Figure 14 Oxygen consumption rate at different temperatures
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
0
1000
2000
3000
4000
5000
6000
7000
8000
Con
cent
ratio
n of
CO
(ppm
)
(a)
0
10
20
30
40
50
60
70
Rate
of C
O p
rodu
ctio
n (1
011 m
ol(
cm3 times
s))
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
(b)
Figure 15 Curves of the CO production rate of coal samples
Advances in Materials Science and Engineering 7
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
32 Viscosity of the Macromolecular Materials Figure 9shows the plots of viscosity versus time for the macromo-lecular materials at different concentrations For each
concentration the viscosity of macromolecular materialsdecreases rapidly within 30mins and then the rate of thedecline is gradually decreased Approximately 250 hourslater the viscosity increased slightly because of the increaseof concentration of the macromolecular materials caused bythe loss of water Subsequently the above-mentioned
T (
)
20
40
60
80
100
120
3500 3000 2500 2000 1500 1000 5004000Wavenumber (cmndash1)
Figure 3 Infrared spectra of macromolecular gel colloids
CH2 CH
C
O
O
CO
CH2
Fe2+
CH
C COONa
COONa
O
O
C O
CH2 CH
CH2 CH CH2 CH CH2 CH
Figure 4 Partial molecular formula of macromolecular colloids
Figure 1 An explosion caused by water injection (high-pressure water column)
Xinjiang
Ningxia
Shanxi
Shaanxi
Inner MongoliaGansuOthers
Xinjiang
Ningxia
Inner Mongolia
Beijing
2458129
2131
199
2179
464244
Shanxi
Shaanxi
Gansu
Figure 2 Major coal-producing areas in China
Advances in Materials Science and Engineering 3
reciprocating trend occurs continuously until the content ofwater is small and the surface is dry In addition the viscosityof the macromolecular materials increases with the increaseof the concentration When the concentration increases to12 the initial viscosity of the macromolecular materialincreases significantly which is about ten times higher than10 Under such conditions because of its large flow re-sistance it is difficult to transport the colloid to the desiredself-ignition area further affecting the fire-prevention effect
33 Rate of Water Loss Macromolecular colloid is a highwater-retaining material and about 99 of its compositionis water +e water retention of macromolecular colloids is akey factor in fire fighting+erefore according to the changeof the mass of the colloid the average water loss per unittime is measured +e experimental environment temper-ature is 20degC +e colloidal concentrations of the macro-molecular colloid were 04 06 08 10 12 and
14 respectively As shown in Figure 10 it can be seen thatthe six curves are substantially coincident With the increaseof time the average water loss decreases first and when it
CH2 +O2
O2H2C
H2C
HC
OOHOO
Figure 5 Chemical adsorption and chemical reaction processes
CH2 +E+
E+
H2C 21
H2C OO
HC
E
Figure 6 Prevention of chemical adsorption and chemical reaction processes by colloids
Table 1 Preparation of colloids with different concentrationsWater (g) 2988 2982 2976 297 2964 2958Macromolecular colloid(g) 12 18 24 30 36 42
Concentration () 04 06 08 10 12 14
Gel
time (
s)
0
20
40
60
80
100
06 08 10 12 1404Concentration ()
Figure 7 Change curve of gel time with concentration
Gel
time (
s)
40 60 80 10020Temperature (degC)
0
4
8
12
16
Figure 8 Change curve of gel time with temperature
040608
101214
Visc
osity
(Pamiddots
)
1 2 3 200 400 6000Time (h)
0
20000
40000
600000
1200000
1800000
Figure 9 Effects of concentration on the viscosity of macromo-lecular colloids
4 Advances in Materials Science and Engineering
reaches a certain threshold it starts to increase and thendecrease +is shows that colloidal concentration has littleeffect on the rate of water loss
A macromolecular colloid with a concentration of 1was prepared +e macromolecular colloids were placed in awater bath at different temperatures (20degC 40degC 60degC 80degCand 100degC) And then the changes of the mass of themacromolecular colloid with time were measured +e re-sults are shown in Figure 11 It can be seen that the averagewater loss rate of the macromolecular colloid increases withincreasing temperature +e average water loss rate for eachtemperature condition has a maximum value +e peakswere 057 gh 147 gh 399 gh 734 gh and 1049 ghrespectively
4 Study on Fire-Fighting Performance ofMacromolecular Colloids
41 Experimental Equipment and Process In this paper aself-designed temperature-programmed experimental sys-tem was used to test the performance of the macromolecularcolloid +e experimental system is shown in Figure 12(a)[28] +e system mainly includes four process gas supplytemperature control gas analysis and tail gas treatment+eloading capacity of the self-made coal sample tank is 1000 gand the structure is shown in Figure 12(b)
+e selected coal samples were mixed with water waterglass colloid (WGC) loess compound colloid (LCC) fly ashcomposite colloid (FACC) and macromolecular colloid(MC) (as shown in Table 2) then soaked for 12 hours andfinally placed on a 05mm wire mesh After no waterdropping they were loaded into a coal sample tank to beginthe experiment Water glass and gelling agents are fromXirsquoan Tianhe Mining Technology Co Ltd
+e treated coal sample was charged into an experi-mental furnace and nitrogen gas was introduced for
30minutes+en the air was allowed and the flow was set to120mlmin+e experiment started from 25degC to 170degC andthe heating rate was 20degCh When the temperature of thecoal sample was higher than 10degC the gas in the coal sampletank was analyzed by gas chromatography
42 Results and Discussion +e experiment was carried outin the Key Laboratory of Mine and Disaster Prevention andControl of Ministry of Education +e ambient temperaturewas 200ndash250degC the relative humidity was 580ndash700 andthe atmospheric pressure was about 1010 kPa
421 Effects of Macromolecular Colloids on Heating Rate+e study of Xu et al [29] showed that the temperature-programmed experimental method is a technique for short-term testing of spontaneous coal combustion Spontaneouscoal oxidation combustion is a dynamic process of nonlineardevelopment [30 31]
It can be seen from Figure 13 that the coal temperatureincreases gradually [32] and the heating process is dividedinto three stages (I lt90degC II 90ndash100degC and III gt100degC)+e resistance effect of various fire-prevention materials ismainly reflected in stage II From 90degC to 100degC each coalsample (No 1 No 2 No 3 No 4 No 5 and No 6) requires48min 55min 826min 373min 550min and 921minrespectively +is shows that the resistance effect of themacromolecular colloid is significantly better than that ofother fire-prevention materials
422 Effects of Macromolecular Colloids on Oxygen Con-sumption Rate As can be seen from Figure 14 the oxygenconsumption rate of coal samples (No 1 No 2 No 3 No 4No 5 and No 6) increased with increasing temperature[33] +e oxygen consumption rate of the raw coal (No 1)was greater than the oxygen consumption rate of the treated
040608
101214
Wat
er lo
ss (g
middothndash1
)
005
010
015
020
025
030
035
100 200 300 400 5000Time (h)
Figure 10 Effects of concentration on the water loss of macro-molecular colloids
20degC40degC60degC
80degC100degC
Wat
er lo
ss (g
middothndash1
)
0 10 20 30 100 200 300 400 500Time (h)
0
2
4
6
8
10
Figure 11 Effects of temperature on the water loss of macro-molecular colloids
Advances in Materials Science and Engineering 5
coal samples (No 2 No 3 No 4 No 5 and No 6) Whenthe coal sample temperature was below 60degC the differencein the rate of heating of various coal samples was small After80degC the heating rate of the coal sample treated with themacromolecular colloid (No 6) was significantly smallerthan that of other coal samples (No 1 No 2 No 3 No 4and No 5)
423 Effects of Macromolecular Colloids on CO Dou et al[34] Xu et al [29] and Deng et al [28] studies showed thatthe emission of CO has a significant dependence on tem-perature So CO has been considered as an effective meansof tracking or predicting coal spontaneous combustionAccordingly we studied the CO concentration of the rawcoal sample and the treated coal sample at various tem-peratures +e results are shown in Figure 15
As can be seen from Figure 15 the amount of COproduced by the treated coal samples (No 2 No 3 No 4No 5 and No 6) was much lower than the amount of COproduced by the raw coal sample (No 1) and among themNo 6 produced the smallest +is shows that the macro-molecular colloid effectively inhibits the oxidation process ofcoal
424 Effects of Macromolecular Colloids on Activation En-ergy (Ea) According to the kinetic theory of reaction the Eain each reaction was different +e lower the Ea is the easierthe reaction is and the faster the reaction rate is +ereforeEa could be used as an indicator of spontaneous coalcombustion propensity [35]
According to the literature [30] the reaction process ofcoal oxidation and temperature rising can be described as
Coal + O2⟶ aCO + bCO2 + others (1)
According to Arrheniusrsquo law the rate of oxidation at anycoal temperature is shown as
Automatic airsource pump
Flow meter
Thermocouplethermometer Programmed heating box Sink Gas chromatograph
(a)
Outlet
Thermocouple
Steel container
Coal sampley
xInlet
(b)
Figure 12 Temperature-programmed experiment of spontaneous coal combustion
Table 2 Treatment of the coal samples
Number Sample Remarks Quantity1 Raw coal Nothing Nothing2 Coal +water Water 2 kg3 Coal +WGC Na2SiO3middot9H2O concentration of 10
NaHCO3 concentration of 4 2 kg
4 Coal + LCC Water-soil ratio is 1 1 and gelling agent added is01 2 kg
5 Coal + FACC Water-fly ash ratio is 1 1 and gelling agent added is01 2 kg
6 Coal +MC Water-macromolecular material ratio is 99 1 2 kg+e proportions are quantity ratios
No 1
No 3No 5No 2No 4
No 6
I
II
III
Tem
pera
ture
(degC)
200 400 600 800 1000 1200 1400 16000Time (min)
0
20
40
60
80
100
120
140
160
180
Figure 13 Law of the change of coal sample temperature with time
6 Advances in Materials Science and Engineering
r Tk( 1113857 r O2( 1113857 r(CO)
a r
CO2( 1113857
b k0C
mO2
expminus Ea
RTk1113888 1113889
(2)
where r(α) is the reaction rate (mol(m3middots)) Tk is thetemperature of coal (degC) a and b are coefficients k0 is theexponential factor CO2
is the molecular strength of oxygenin air (molm3) m is the reaction series Ea denotes theactivity energy (kJmol) and R is the gas constant (8314 J(degCmiddotmol))
During the experiment it is assumed that the air flowsalong the longitudinal direction of the coal sample tank that
is the positive direction of y as shown in Figure 12(b) +erate of CO generation at any point in the y direction is
dVco S middot ak0Cm
O2exp minus EaRT( 1113857
k middot vairdy (3)
where Vco is the CO concentration (ppm) S is the sectionalarea of the coal sample tank (m2) vair is the airflow velocity(m3s) and k is the concentration conversion coefficient(224times109)
Integrating the above formula (3) we obtain
1113946Pout
Pin
dVco 1113946L
0
S middot ak0CmO2
exp minus EaRT( 1113857
k middot vairdy (4)
No 1No 2No 3
No 4No 5No 6
O2 (
)
3
6
9
12
15
18
21
40 60 80 100 120 140 160 180 20020Temperatrue (degC)
(a)
No 1No 2No 3
No 4No 5No 6
Oxy
gen
cons
umpt
ion
rate
(10ndash1
1 m
olmiddotcm
ndash3middotsndash1
)
40 60 80 100 120 140 160 180 20020Temperature (degC)
0200400600800
100012001400160018002000
(b)
Figure 14 Oxygen consumption rate at different temperatures
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
0
1000
2000
3000
4000
5000
6000
7000
8000
Con
cent
ratio
n of
CO
(ppm
)
(a)
0
10
20
30
40
50
60
70
Rate
of C
O p
rodu
ctio
n (1
011 m
ol(
cm3 times
s))
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
(b)
Figure 15 Curves of the CO production rate of coal samples
Advances in Materials Science and Engineering 7
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
reciprocating trend occurs continuously until the content ofwater is small and the surface is dry In addition the viscosityof the macromolecular materials increases with the increaseof the concentration When the concentration increases to12 the initial viscosity of the macromolecular materialincreases significantly which is about ten times higher than10 Under such conditions because of its large flow re-sistance it is difficult to transport the colloid to the desiredself-ignition area further affecting the fire-prevention effect
33 Rate of Water Loss Macromolecular colloid is a highwater-retaining material and about 99 of its compositionis water +e water retention of macromolecular colloids is akey factor in fire fighting+erefore according to the changeof the mass of the colloid the average water loss per unittime is measured +e experimental environment temper-ature is 20degC +e colloidal concentrations of the macro-molecular colloid were 04 06 08 10 12 and
14 respectively As shown in Figure 10 it can be seen thatthe six curves are substantially coincident With the increaseof time the average water loss decreases first and when it
CH2 +O2
O2H2C
H2C
HC
OOHOO
Figure 5 Chemical adsorption and chemical reaction processes
CH2 +E+
E+
H2C 21
H2C OO
HC
E
Figure 6 Prevention of chemical adsorption and chemical reaction processes by colloids
Table 1 Preparation of colloids with different concentrationsWater (g) 2988 2982 2976 297 2964 2958Macromolecular colloid(g) 12 18 24 30 36 42
Concentration () 04 06 08 10 12 14
Gel
time (
s)
0
20
40
60
80
100
06 08 10 12 1404Concentration ()
Figure 7 Change curve of gel time with concentration
Gel
time (
s)
40 60 80 10020Temperature (degC)
0
4
8
12
16
Figure 8 Change curve of gel time with temperature
040608
101214
Visc
osity
(Pamiddots
)
1 2 3 200 400 6000Time (h)
0
20000
40000
600000
1200000
1800000
Figure 9 Effects of concentration on the viscosity of macromo-lecular colloids
4 Advances in Materials Science and Engineering
reaches a certain threshold it starts to increase and thendecrease +is shows that colloidal concentration has littleeffect on the rate of water loss
A macromolecular colloid with a concentration of 1was prepared +e macromolecular colloids were placed in awater bath at different temperatures (20degC 40degC 60degC 80degCand 100degC) And then the changes of the mass of themacromolecular colloid with time were measured +e re-sults are shown in Figure 11 It can be seen that the averagewater loss rate of the macromolecular colloid increases withincreasing temperature +e average water loss rate for eachtemperature condition has a maximum value +e peakswere 057 gh 147 gh 399 gh 734 gh and 1049 ghrespectively
4 Study on Fire-Fighting Performance ofMacromolecular Colloids
41 Experimental Equipment and Process In this paper aself-designed temperature-programmed experimental sys-tem was used to test the performance of the macromolecularcolloid +e experimental system is shown in Figure 12(a)[28] +e system mainly includes four process gas supplytemperature control gas analysis and tail gas treatment+eloading capacity of the self-made coal sample tank is 1000 gand the structure is shown in Figure 12(b)
+e selected coal samples were mixed with water waterglass colloid (WGC) loess compound colloid (LCC) fly ashcomposite colloid (FACC) and macromolecular colloid(MC) (as shown in Table 2) then soaked for 12 hours andfinally placed on a 05mm wire mesh After no waterdropping they were loaded into a coal sample tank to beginthe experiment Water glass and gelling agents are fromXirsquoan Tianhe Mining Technology Co Ltd
+e treated coal sample was charged into an experi-mental furnace and nitrogen gas was introduced for
30minutes+en the air was allowed and the flow was set to120mlmin+e experiment started from 25degC to 170degC andthe heating rate was 20degCh When the temperature of thecoal sample was higher than 10degC the gas in the coal sampletank was analyzed by gas chromatography
42 Results and Discussion +e experiment was carried outin the Key Laboratory of Mine and Disaster Prevention andControl of Ministry of Education +e ambient temperaturewas 200ndash250degC the relative humidity was 580ndash700 andthe atmospheric pressure was about 1010 kPa
421 Effects of Macromolecular Colloids on Heating Rate+e study of Xu et al [29] showed that the temperature-programmed experimental method is a technique for short-term testing of spontaneous coal combustion Spontaneouscoal oxidation combustion is a dynamic process of nonlineardevelopment [30 31]
It can be seen from Figure 13 that the coal temperatureincreases gradually [32] and the heating process is dividedinto three stages (I lt90degC II 90ndash100degC and III gt100degC)+e resistance effect of various fire-prevention materials ismainly reflected in stage II From 90degC to 100degC each coalsample (No 1 No 2 No 3 No 4 No 5 and No 6) requires48min 55min 826min 373min 550min and 921minrespectively +is shows that the resistance effect of themacromolecular colloid is significantly better than that ofother fire-prevention materials
422 Effects of Macromolecular Colloids on Oxygen Con-sumption Rate As can be seen from Figure 14 the oxygenconsumption rate of coal samples (No 1 No 2 No 3 No 4No 5 and No 6) increased with increasing temperature[33] +e oxygen consumption rate of the raw coal (No 1)was greater than the oxygen consumption rate of the treated
040608
101214
Wat
er lo
ss (g
middothndash1
)
005
010
015
020
025
030
035
100 200 300 400 5000Time (h)
Figure 10 Effects of concentration on the water loss of macro-molecular colloids
20degC40degC60degC
80degC100degC
Wat
er lo
ss (g
middothndash1
)
0 10 20 30 100 200 300 400 500Time (h)
0
2
4
6
8
10
Figure 11 Effects of temperature on the water loss of macro-molecular colloids
Advances in Materials Science and Engineering 5
coal samples (No 2 No 3 No 4 No 5 and No 6) Whenthe coal sample temperature was below 60degC the differencein the rate of heating of various coal samples was small After80degC the heating rate of the coal sample treated with themacromolecular colloid (No 6) was significantly smallerthan that of other coal samples (No 1 No 2 No 3 No 4and No 5)
423 Effects of Macromolecular Colloids on CO Dou et al[34] Xu et al [29] and Deng et al [28] studies showed thatthe emission of CO has a significant dependence on tem-perature So CO has been considered as an effective meansof tracking or predicting coal spontaneous combustionAccordingly we studied the CO concentration of the rawcoal sample and the treated coal sample at various tem-peratures +e results are shown in Figure 15
As can be seen from Figure 15 the amount of COproduced by the treated coal samples (No 2 No 3 No 4No 5 and No 6) was much lower than the amount of COproduced by the raw coal sample (No 1) and among themNo 6 produced the smallest +is shows that the macro-molecular colloid effectively inhibits the oxidation process ofcoal
424 Effects of Macromolecular Colloids on Activation En-ergy (Ea) According to the kinetic theory of reaction the Eain each reaction was different +e lower the Ea is the easierthe reaction is and the faster the reaction rate is +ereforeEa could be used as an indicator of spontaneous coalcombustion propensity [35]
According to the literature [30] the reaction process ofcoal oxidation and temperature rising can be described as
Coal + O2⟶ aCO + bCO2 + others (1)
According to Arrheniusrsquo law the rate of oxidation at anycoal temperature is shown as
Automatic airsource pump
Flow meter
Thermocouplethermometer Programmed heating box Sink Gas chromatograph
(a)
Outlet
Thermocouple
Steel container
Coal sampley
xInlet
(b)
Figure 12 Temperature-programmed experiment of spontaneous coal combustion
Table 2 Treatment of the coal samples
Number Sample Remarks Quantity1 Raw coal Nothing Nothing2 Coal +water Water 2 kg3 Coal +WGC Na2SiO3middot9H2O concentration of 10
NaHCO3 concentration of 4 2 kg
4 Coal + LCC Water-soil ratio is 1 1 and gelling agent added is01 2 kg
5 Coal + FACC Water-fly ash ratio is 1 1 and gelling agent added is01 2 kg
6 Coal +MC Water-macromolecular material ratio is 99 1 2 kg+e proportions are quantity ratios
No 1
No 3No 5No 2No 4
No 6
I
II
III
Tem
pera
ture
(degC)
200 400 600 800 1000 1200 1400 16000Time (min)
0
20
40
60
80
100
120
140
160
180
Figure 13 Law of the change of coal sample temperature with time
6 Advances in Materials Science and Engineering
r Tk( 1113857 r O2( 1113857 r(CO)
a r
CO2( 1113857
b k0C
mO2
expminus Ea
RTk1113888 1113889
(2)
where r(α) is the reaction rate (mol(m3middots)) Tk is thetemperature of coal (degC) a and b are coefficients k0 is theexponential factor CO2
is the molecular strength of oxygenin air (molm3) m is the reaction series Ea denotes theactivity energy (kJmol) and R is the gas constant (8314 J(degCmiddotmol))
During the experiment it is assumed that the air flowsalong the longitudinal direction of the coal sample tank that
is the positive direction of y as shown in Figure 12(b) +erate of CO generation at any point in the y direction is
dVco S middot ak0Cm
O2exp minus EaRT( 1113857
k middot vairdy (3)
where Vco is the CO concentration (ppm) S is the sectionalarea of the coal sample tank (m2) vair is the airflow velocity(m3s) and k is the concentration conversion coefficient(224times109)
Integrating the above formula (3) we obtain
1113946Pout
Pin
dVco 1113946L
0
S middot ak0CmO2
exp minus EaRT( 1113857
k middot vairdy (4)
No 1No 2No 3
No 4No 5No 6
O2 (
)
3
6
9
12
15
18
21
40 60 80 100 120 140 160 180 20020Temperatrue (degC)
(a)
No 1No 2No 3
No 4No 5No 6
Oxy
gen
cons
umpt
ion
rate
(10ndash1
1 m
olmiddotcm
ndash3middotsndash1
)
40 60 80 100 120 140 160 180 20020Temperature (degC)
0200400600800
100012001400160018002000
(b)
Figure 14 Oxygen consumption rate at different temperatures
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
0
1000
2000
3000
4000
5000
6000
7000
8000
Con
cent
ratio
n of
CO
(ppm
)
(a)
0
10
20
30
40
50
60
70
Rate
of C
O p
rodu
ctio
n (1
011 m
ol(
cm3 times
s))
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
(b)
Figure 15 Curves of the CO production rate of coal samples
Advances in Materials Science and Engineering 7
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
reaches a certain threshold it starts to increase and thendecrease +is shows that colloidal concentration has littleeffect on the rate of water loss
A macromolecular colloid with a concentration of 1was prepared +e macromolecular colloids were placed in awater bath at different temperatures (20degC 40degC 60degC 80degCand 100degC) And then the changes of the mass of themacromolecular colloid with time were measured +e re-sults are shown in Figure 11 It can be seen that the averagewater loss rate of the macromolecular colloid increases withincreasing temperature +e average water loss rate for eachtemperature condition has a maximum value +e peakswere 057 gh 147 gh 399 gh 734 gh and 1049 ghrespectively
4 Study on Fire-Fighting Performance ofMacromolecular Colloids
41 Experimental Equipment and Process In this paper aself-designed temperature-programmed experimental sys-tem was used to test the performance of the macromolecularcolloid +e experimental system is shown in Figure 12(a)[28] +e system mainly includes four process gas supplytemperature control gas analysis and tail gas treatment+eloading capacity of the self-made coal sample tank is 1000 gand the structure is shown in Figure 12(b)
+e selected coal samples were mixed with water waterglass colloid (WGC) loess compound colloid (LCC) fly ashcomposite colloid (FACC) and macromolecular colloid(MC) (as shown in Table 2) then soaked for 12 hours andfinally placed on a 05mm wire mesh After no waterdropping they were loaded into a coal sample tank to beginthe experiment Water glass and gelling agents are fromXirsquoan Tianhe Mining Technology Co Ltd
+e treated coal sample was charged into an experi-mental furnace and nitrogen gas was introduced for
30minutes+en the air was allowed and the flow was set to120mlmin+e experiment started from 25degC to 170degC andthe heating rate was 20degCh When the temperature of thecoal sample was higher than 10degC the gas in the coal sampletank was analyzed by gas chromatography
42 Results and Discussion +e experiment was carried outin the Key Laboratory of Mine and Disaster Prevention andControl of Ministry of Education +e ambient temperaturewas 200ndash250degC the relative humidity was 580ndash700 andthe atmospheric pressure was about 1010 kPa
421 Effects of Macromolecular Colloids on Heating Rate+e study of Xu et al [29] showed that the temperature-programmed experimental method is a technique for short-term testing of spontaneous coal combustion Spontaneouscoal oxidation combustion is a dynamic process of nonlineardevelopment [30 31]
It can be seen from Figure 13 that the coal temperatureincreases gradually [32] and the heating process is dividedinto three stages (I lt90degC II 90ndash100degC and III gt100degC)+e resistance effect of various fire-prevention materials ismainly reflected in stage II From 90degC to 100degC each coalsample (No 1 No 2 No 3 No 4 No 5 and No 6) requires48min 55min 826min 373min 550min and 921minrespectively +is shows that the resistance effect of themacromolecular colloid is significantly better than that ofother fire-prevention materials
422 Effects of Macromolecular Colloids on Oxygen Con-sumption Rate As can be seen from Figure 14 the oxygenconsumption rate of coal samples (No 1 No 2 No 3 No 4No 5 and No 6) increased with increasing temperature[33] +e oxygen consumption rate of the raw coal (No 1)was greater than the oxygen consumption rate of the treated
040608
101214
Wat
er lo
ss (g
middothndash1
)
005
010
015
020
025
030
035
100 200 300 400 5000Time (h)
Figure 10 Effects of concentration on the water loss of macro-molecular colloids
20degC40degC60degC
80degC100degC
Wat
er lo
ss (g
middothndash1
)
0 10 20 30 100 200 300 400 500Time (h)
0
2
4
6
8
10
Figure 11 Effects of temperature on the water loss of macro-molecular colloids
Advances in Materials Science and Engineering 5
coal samples (No 2 No 3 No 4 No 5 and No 6) Whenthe coal sample temperature was below 60degC the differencein the rate of heating of various coal samples was small After80degC the heating rate of the coal sample treated with themacromolecular colloid (No 6) was significantly smallerthan that of other coal samples (No 1 No 2 No 3 No 4and No 5)
423 Effects of Macromolecular Colloids on CO Dou et al[34] Xu et al [29] and Deng et al [28] studies showed thatthe emission of CO has a significant dependence on tem-perature So CO has been considered as an effective meansof tracking or predicting coal spontaneous combustionAccordingly we studied the CO concentration of the rawcoal sample and the treated coal sample at various tem-peratures +e results are shown in Figure 15
As can be seen from Figure 15 the amount of COproduced by the treated coal samples (No 2 No 3 No 4No 5 and No 6) was much lower than the amount of COproduced by the raw coal sample (No 1) and among themNo 6 produced the smallest +is shows that the macro-molecular colloid effectively inhibits the oxidation process ofcoal
424 Effects of Macromolecular Colloids on Activation En-ergy (Ea) According to the kinetic theory of reaction the Eain each reaction was different +e lower the Ea is the easierthe reaction is and the faster the reaction rate is +ereforeEa could be used as an indicator of spontaneous coalcombustion propensity [35]
According to the literature [30] the reaction process ofcoal oxidation and temperature rising can be described as
Coal + O2⟶ aCO + bCO2 + others (1)
According to Arrheniusrsquo law the rate of oxidation at anycoal temperature is shown as
Automatic airsource pump
Flow meter
Thermocouplethermometer Programmed heating box Sink Gas chromatograph
(a)
Outlet
Thermocouple
Steel container
Coal sampley
xInlet
(b)
Figure 12 Temperature-programmed experiment of spontaneous coal combustion
Table 2 Treatment of the coal samples
Number Sample Remarks Quantity1 Raw coal Nothing Nothing2 Coal +water Water 2 kg3 Coal +WGC Na2SiO3middot9H2O concentration of 10
NaHCO3 concentration of 4 2 kg
4 Coal + LCC Water-soil ratio is 1 1 and gelling agent added is01 2 kg
5 Coal + FACC Water-fly ash ratio is 1 1 and gelling agent added is01 2 kg
6 Coal +MC Water-macromolecular material ratio is 99 1 2 kg+e proportions are quantity ratios
No 1
No 3No 5No 2No 4
No 6
I
II
III
Tem
pera
ture
(degC)
200 400 600 800 1000 1200 1400 16000Time (min)
0
20
40
60
80
100
120
140
160
180
Figure 13 Law of the change of coal sample temperature with time
6 Advances in Materials Science and Engineering
r Tk( 1113857 r O2( 1113857 r(CO)
a r
CO2( 1113857
b k0C
mO2
expminus Ea
RTk1113888 1113889
(2)
where r(α) is the reaction rate (mol(m3middots)) Tk is thetemperature of coal (degC) a and b are coefficients k0 is theexponential factor CO2
is the molecular strength of oxygenin air (molm3) m is the reaction series Ea denotes theactivity energy (kJmol) and R is the gas constant (8314 J(degCmiddotmol))
During the experiment it is assumed that the air flowsalong the longitudinal direction of the coal sample tank that
is the positive direction of y as shown in Figure 12(b) +erate of CO generation at any point in the y direction is
dVco S middot ak0Cm
O2exp minus EaRT( 1113857
k middot vairdy (3)
where Vco is the CO concentration (ppm) S is the sectionalarea of the coal sample tank (m2) vair is the airflow velocity(m3s) and k is the concentration conversion coefficient(224times109)
Integrating the above formula (3) we obtain
1113946Pout
Pin
dVco 1113946L
0
S middot ak0CmO2
exp minus EaRT( 1113857
k middot vairdy (4)
No 1No 2No 3
No 4No 5No 6
O2 (
)
3
6
9
12
15
18
21
40 60 80 100 120 140 160 180 20020Temperatrue (degC)
(a)
No 1No 2No 3
No 4No 5No 6
Oxy
gen
cons
umpt
ion
rate
(10ndash1
1 m
olmiddotcm
ndash3middotsndash1
)
40 60 80 100 120 140 160 180 20020Temperature (degC)
0200400600800
100012001400160018002000
(b)
Figure 14 Oxygen consumption rate at different temperatures
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
0
1000
2000
3000
4000
5000
6000
7000
8000
Con
cent
ratio
n of
CO
(ppm
)
(a)
0
10
20
30
40
50
60
70
Rate
of C
O p
rodu
ctio
n (1
011 m
ol(
cm3 times
s))
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
(b)
Figure 15 Curves of the CO production rate of coal samples
Advances in Materials Science and Engineering 7
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
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Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
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Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
coal samples (No 2 No 3 No 4 No 5 and No 6) Whenthe coal sample temperature was below 60degC the differencein the rate of heating of various coal samples was small After80degC the heating rate of the coal sample treated with themacromolecular colloid (No 6) was significantly smallerthan that of other coal samples (No 1 No 2 No 3 No 4and No 5)
423 Effects of Macromolecular Colloids on CO Dou et al[34] Xu et al [29] and Deng et al [28] studies showed thatthe emission of CO has a significant dependence on tem-perature So CO has been considered as an effective meansof tracking or predicting coal spontaneous combustionAccordingly we studied the CO concentration of the rawcoal sample and the treated coal sample at various tem-peratures +e results are shown in Figure 15
As can be seen from Figure 15 the amount of COproduced by the treated coal samples (No 2 No 3 No 4No 5 and No 6) was much lower than the amount of COproduced by the raw coal sample (No 1) and among themNo 6 produced the smallest +is shows that the macro-molecular colloid effectively inhibits the oxidation process ofcoal
424 Effects of Macromolecular Colloids on Activation En-ergy (Ea) According to the kinetic theory of reaction the Eain each reaction was different +e lower the Ea is the easierthe reaction is and the faster the reaction rate is +ereforeEa could be used as an indicator of spontaneous coalcombustion propensity [35]
According to the literature [30] the reaction process ofcoal oxidation and temperature rising can be described as
Coal + O2⟶ aCO + bCO2 + others (1)
According to Arrheniusrsquo law the rate of oxidation at anycoal temperature is shown as
Automatic airsource pump
Flow meter
Thermocouplethermometer Programmed heating box Sink Gas chromatograph
(a)
Outlet
Thermocouple
Steel container
Coal sampley
xInlet
(b)
Figure 12 Temperature-programmed experiment of spontaneous coal combustion
Table 2 Treatment of the coal samples
Number Sample Remarks Quantity1 Raw coal Nothing Nothing2 Coal +water Water 2 kg3 Coal +WGC Na2SiO3middot9H2O concentration of 10
NaHCO3 concentration of 4 2 kg
4 Coal + LCC Water-soil ratio is 1 1 and gelling agent added is01 2 kg
5 Coal + FACC Water-fly ash ratio is 1 1 and gelling agent added is01 2 kg
6 Coal +MC Water-macromolecular material ratio is 99 1 2 kg+e proportions are quantity ratios
No 1
No 3No 5No 2No 4
No 6
I
II
III
Tem
pera
ture
(degC)
200 400 600 800 1000 1200 1400 16000Time (min)
0
20
40
60
80
100
120
140
160
180
Figure 13 Law of the change of coal sample temperature with time
6 Advances in Materials Science and Engineering
r Tk( 1113857 r O2( 1113857 r(CO)
a r
CO2( 1113857
b k0C
mO2
expminus Ea
RTk1113888 1113889
(2)
where r(α) is the reaction rate (mol(m3middots)) Tk is thetemperature of coal (degC) a and b are coefficients k0 is theexponential factor CO2
is the molecular strength of oxygenin air (molm3) m is the reaction series Ea denotes theactivity energy (kJmol) and R is the gas constant (8314 J(degCmiddotmol))
During the experiment it is assumed that the air flowsalong the longitudinal direction of the coal sample tank that
is the positive direction of y as shown in Figure 12(b) +erate of CO generation at any point in the y direction is
dVco S middot ak0Cm
O2exp minus EaRT( 1113857
k middot vairdy (3)
where Vco is the CO concentration (ppm) S is the sectionalarea of the coal sample tank (m2) vair is the airflow velocity(m3s) and k is the concentration conversion coefficient(224times109)
Integrating the above formula (3) we obtain
1113946Pout
Pin
dVco 1113946L
0
S middot ak0CmO2
exp minus EaRT( 1113857
k middot vairdy (4)
No 1No 2No 3
No 4No 5No 6
O2 (
)
3
6
9
12
15
18
21
40 60 80 100 120 140 160 180 20020Temperatrue (degC)
(a)
No 1No 2No 3
No 4No 5No 6
Oxy
gen
cons
umpt
ion
rate
(10ndash1
1 m
olmiddotcm
ndash3middotsndash1
)
40 60 80 100 120 140 160 180 20020Temperature (degC)
0200400600800
100012001400160018002000
(b)
Figure 14 Oxygen consumption rate at different temperatures
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
0
1000
2000
3000
4000
5000
6000
7000
8000
Con
cent
ratio
n of
CO
(ppm
)
(a)
0
10
20
30
40
50
60
70
Rate
of C
O p
rodu
ctio
n (1
011 m
ol(
cm3 times
s))
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
(b)
Figure 15 Curves of the CO production rate of coal samples
Advances in Materials Science and Engineering 7
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
r Tk( 1113857 r O2( 1113857 r(CO)
a r
CO2( 1113857
b k0C
mO2
expminus Ea
RTk1113888 1113889
(2)
where r(α) is the reaction rate (mol(m3middots)) Tk is thetemperature of coal (degC) a and b are coefficients k0 is theexponential factor CO2
is the molecular strength of oxygenin air (molm3) m is the reaction series Ea denotes theactivity energy (kJmol) and R is the gas constant (8314 J(degCmiddotmol))
During the experiment it is assumed that the air flowsalong the longitudinal direction of the coal sample tank that
is the positive direction of y as shown in Figure 12(b) +erate of CO generation at any point in the y direction is
dVco S middot ak0Cm
O2exp minus EaRT( 1113857
k middot vairdy (3)
where Vco is the CO concentration (ppm) S is the sectionalarea of the coal sample tank (m2) vair is the airflow velocity(m3s) and k is the concentration conversion coefficient(224times109)
Integrating the above formula (3) we obtain
1113946Pout
Pin
dVco 1113946L
0
S middot ak0CmO2
exp minus EaRT( 1113857
k middot vairdy (4)
No 1No 2No 3
No 4No 5No 6
O2 (
)
3
6
9
12
15
18
21
40 60 80 100 120 140 160 180 20020Temperatrue (degC)
(a)
No 1No 2No 3
No 4No 5No 6
Oxy
gen
cons
umpt
ion
rate
(10ndash1
1 m
olmiddotcm
ndash3middotsndash1
)
40 60 80 100 120 140 160 180 20020Temperature (degC)
0200400600800
100012001400160018002000
(b)
Figure 14 Oxygen consumption rate at different temperatures
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
0
1000
2000
3000
4000
5000
6000
7000
8000
Con
cent
ratio
n of
CO
(ppm
)
(a)
0
10
20
30
40
50
60
70
Rate
of C
O p
rodu
ctio
n (1
011 m
ol(
cm3 times
s))
No 1No 2No 3
No 4No 5No 6
40 60 80 100 120 140 160 180 20020Temperature (degC)
(b)
Figure 15 Curves of the CO production rate of coal samples
Advances in Materials Science and Engineering 7
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
where Pout is the CO concentration at the exit of the coalsample tank (ppm) and L is the height of the coal sample
From formula (4) we obtain
lnPout minusEa
Rmiddot1
Tk+ ln
aLk0SCmO2
k middot vair (5)
According to the relationship between ln(Pout) and 1Tkin (5) the apparent activation energy (Ea) can be calculated[29 35 36] Figure 16 shows the linear relationship betweenln(Pout) and 1Tk for six coal samples (No 1 No 2 No 3No 4 No 5 and No 6)
+e Ea of the corresponding coal sample is obtained bysubstituting the slope value fitted in Figure 16 into equation(5) +e results are shown in Table 3
Obviously the Ea of the treated coal samples (No 2No 3 No 4 No 5 and No 6) is greater than that of the rawcoal sample so their oxidation reaction rate is small +at isto say the active groups of the coal are suppressed and thecoal oxygen reaction is decelerated [37] +at is all kinds ofmaterials have the role of inhibition of coal oxidation In thetreated coal sample the Ea of No 6 is highest which is10200 kJmol It indicates that the resistivity of the
macromolecular colloid is better than that of water waterglass loess compound colloids and fly ash composite col-loids +e flame-retardant ability of several materials fromlarge to small is macromolecular colloids water glass col-loids fly ash composite colloids loess compound colloidsand water
5 Conclusions
A macromolecular colloid for coal seam fire fighting wasdeveloped and its physical and chemical properties and firesuppression performance were analyzed +e followingconclusions are drawn from this study
(1) +e macromolecular material has some crosslinkingbonds When it encounters water it will swell andcannot be dissolved and a lot of water is controlledin the macromolecular colloid Macromolecular
No 1
ln(P
out)
y = ndash821072x + 2683R2 = 9958
303540455055606570758085
00023 00024 00025 00026000221Tk
(a)
ln(P
out)
No 2
y = ndash899627x + 2837R2 = 9994
00023 00024 00025 00026000221Tk
303540455055606570758085
(b)
ln(P
out)
y = ndash1161737x + 3337R2 = 9938
No 3
00023 00024 00025 00026000221Tk
303540455055606570758085
(c)
ln(P
out)
No 4
y = ndash1009183x + 3081R2 = 9871
00023 00024 00025 00026000221Tk
303540455055606570758085
(d)
ln(P
out)
y = ndash1066944x + 3189R2 = 9946
No 5
00023 00024 00025 00026000221Tk
303540455055606570758085
(e)
ln(P
out)
No 6
y = ndash1226892x + 3413R2 = 9920
00023 00024 00025 00026000221Tk
303540455055606570758085
(f )
Figure 16 Relation between ln (Pout) and 1Tk of coal samples
Table 3 Activation energy (Ea) of the coal samples
Coal sample No 1 No 2 No 3 No 4 No 5 No 6Ea (kJmol) 6826 7479 9659 8390 8871 10200
8 Advances in Materials Science and Engineering
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
materials and water can be mixed into a mixture ofmacromolecular colloids+e colloid mainly consistsof organic and inorganic components Organiccomponents are mainly mesh structures
(2) +e concentration of a few thousandths of themacromolecular materials can be successfullyformed into gel +is shows that the macromolecularmaterials have a stronger water absorption propertyWith the increase of concentration the gel time ofthe macromolecular colloid gradually decreasesWith the increase of temperature the gel time ofmacromolecular colloid gradually decreases
(3) +e concentration has little effect on the water loss ofmacromolecular colloids +e effect of temperatureon the water loss of macromolecular colloids ishigher +e higher the temperature is the higher thewater loss value is
(4) +e heating rate of coal samples treated with mac-romolecular colloids is lower than that of coalsamples treated with other fire-extinguishing ma-terials +e rate of oxygen consumption the rate ofCO generation and the rate of CO2 generation of thecoal treated by macromolecular colloids are lowerthan those of the coal treated by other fire-extin-guishing materials Macromolecular colloids sup-press the oxidation and temperature rising byincreasing the Ea and they also have the ability ofwrapping oxygen
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work was supported by the National Natural ScienceFoundation of China (Grant nos 51804245 and 51504186)and National Key RampD Projects (Programs2016YFC0801802 and 2018YFC0808201)
References
[1] J Deng Y Xiao J Lu H Wen and Y Jin ldquoApplication ofcomposite fly ash gel to extinguish outcrop coal fires inChinardquo Natural Hazards vol 79 no 2 pp 881ndash898 2015
[2] V V Sharygin E V Sokol and D I Belakovskii ldquoFayalite-sekaninaite paralava from the Ravat coal fire (Central Taji-kistan)rdquo Russian Geology and Geophysics vol 50 no 8pp 703ndash721 2009
[3] Z Song and C Kuenzer ldquoCoal fires in China over the lastdecade a comprehensive reviewrdquo International Journal ofCoal Geology vol 133 pp 72ndash99 2014
[4] C Kuenzer J Zhang A Tetzlaff et al ldquoUncontrolled coal firesand their environmental impacts investigating two arid
mining regions in North-Central Chinardquo Applied Geographyvol 27 no 1 pp 42ndash62 2007
[5] J Deng Y Xiao Q W Li J H Lu and H Wen ldquoExperi-mental studies of spontaneous combustion and anaerobiccooling of coalrdquo Fuel vol 157 pp 261ndash269 2015
[6] H Wen S X Fan D Zhang W F Wang J Guo andQ F Sun ldquoExperimental study and application of a novelfoamed concrete to yield airtight walls in coal minesrdquo Ad-vances in Materials Science and Engineering vol 2018 ArticleID 9620935 13 pages 2018
[7] E L Heffern and D Coates ldquoGeologic history of natural coal-bed fires Powder River basin USArdquo International Journal ofCoal Geology vol 59 no 1-2 pp 25ndash47 2004
[8] M A Engle L F Radke L H Edward et al ldquoGas emissionsminerals and tars associated with three coal fires PowderRiver basin USArdquo Science of the Total Environment vol 420pp 146ndash159 2012
[9] T S Ide N Crook and F M Orr ldquoMagnetometer mea-surements to characterize a subsurface coal firerdquo InternationalJournal of Coal Geology vol 87 no 3-4 pp 190ndash196 2011
[10] J Macnamara ldquo+e Hazelwood coal mine fire lessons fromcrisis miscommunication and misunderstandingrdquo CaseStudies in Strategic Communication vol 4 pp 1ndash20 2015
[11] G Fisher P Torre and A Marshall ldquoHazelwood open-cutcoal mine firerdquo Air Quality and Climate Change vol 49 no 1pp 23ndash27 2015
[12] A K Saraf A Prakash S Sengupta and R P GupatldquoLandsat-TM data for estimating ground temperature anddepth of subsurface coal fire in the Jharia coalfield IndiardquoInternational Journal of Remote Sensing vol 16 no 12pp 2111ndash2124 1995
[13] V Srivardhan S Pal J Vaish S Kumar A K Bhart andP Priyam ldquoParticle swarm optimization inversion of self-potential data for depth estimation of coal fires over eastBasuria colliery Jharia coalfield Indiardquo Environmental EarthSciences vol 75 no 8 pp 1ndash12 2016
[14] A Raju A Singh S Kumar and P Pati ldquoTemporal moni-toring of coal fires in Jharia coalfield Indiardquo EnvironmentalEarth Sciences vol 75 no 12 pp 1ndash15 2016
[15] J D N Pone K A A Hein G B Stracher et al ldquo+espontaneous combustion of coal and its by-products in theWitbank and Sasolburg coalfields of South Africardquo In-ternational Journal of Coal Geology vol 72 no 2 pp 124ndash1402007
[16] F G Bell S E T Bullock T F J Halbich and P LindsayldquoEnvironmental impacts associated with an abandoned minein the Witbank coalfield South Africardquo International Journalof Coal Geology vol 45 no 2-3 pp 195ndash216 2001
[17] H Wen Z Yu J Deng and X Zhai ldquoSpontaneous ignitioncharacteristics of coal in a large-scale furnace an experimentaland numerical investigationrdquo Applied Aermal Engineeringvol 114 pp 583ndash592 2017
[18] M J McPherson ldquoDevelopment and control of open fires incoal mine entriesrdquo in Proceeding of the 6th US Mine Venti-lation Symposium pp 197ndash202 Salt Lake City Utah June1993
[19] S K Ray and R P Singh ldquoRecent developments and practicesto control fire in undergound coal mines fire in undergroundcoal minesrdquo Fire Technology vol 43 no 4 pp 285ndash300 2007
[20] G J Colaizzi ldquoPrevention control andor extinguishment ofcoal seam fires using cellular groutrdquo International Journal ofCoal Geology vol 59 no 1-2 pp 75ndash81 2004
[21] F Zhou W Ren D Wang T Song X Li and Y ZhangldquoApplication of three-phase foam to fight an extraordinarily
Advances in Materials Science and Engineering 9
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
serious coal mine firerdquo International Journal of Coal Geologyvol 67 no 1-2 pp 95ndash100 2006
[22] B T Qin L L Zhang and Y Lu ldquoPreparation and inhibitioncharacteristic of multi-phase foamed gel for preventingspontaneous combustion of coalrdquo Advanced Materials Re-search vol 634ndash638 pp 3678ndash3682 2013
[23] W Cheng X Hu J Xie and Y Zhao ldquoAn intelligent geldesigned to control the spontaneous combustion of coal fireprevention and extinguishing propertiesrdquo Fuel vol 210pp 826ndash835 2017
[24] Y Xiao S-J Ren J Deng and C-M Shu ldquoComparativeanalysis of thermokinetic behavior and gaseous productsbetween first and second coal spontaneous combustionrdquo Fuelvol 227 pp 325ndash333 2018
[25] F-S Cui B Laiwang C-M Shu and J-C Jiang ldquoInhibitingeffect of imidazolium-based ionic liquids on the spontaneouscombustion characteristics of ligniterdquo Fuel vol 217pp 508ndash514 2018
[26] X Zhong L Kan H Xin B Qin and G Dou ldquo+ermal effectsand active group differentiation of low-rank coal during low-temperature oxidation under vacuum drying after waterimmersionrdquo Fuel vol 236 pp 1204ndash1212 2019
[27] Z L ShaoMagnetic and Electrical Signature of Coal Fires andComprehensive Detection Methodology China University ofMining and Technology Xuzhou China 2017 in Chinese
[28] J Deng J Zhao Y Zhang et al ldquo+ermal analysis ofspontaneous combustion behavior of partially oxidized coalrdquoProcess Safety and Environmental Protection vol 104pp 218ndash224 2016
[29] Y-L Xu D-M Wang L-Y Wang X-X Zhong andT-X Chu ldquoExperimental research on inhibition perfor-mances of the sand-suspended colloid for coal spontaneouscombustionrdquo Safety Science vol 50 no 4 pp 822ndash827 2012
[30] H Wang B Z Dlugogorski and E M Kennedy ldquoKineticmodeling of low-temperature oxidation of coalrdquo Combustionand Flame vol 131 no 4 pp 452ndash464 2002
[31] C Semsogut and A IbrahimCinar ldquoResearch on the tendencyof Ermenek district coals to spontaneous combustionrdquoMineral Resources Engineering vol 9 no 4 pp 421ndash427 2000
[32] F Buzek and Z Lnenickova ldquoTemperature programmeddesorption of coal gasesmdashchemical and carbon isotopecompositionrdquo Fuel vol 89 no 7 pp 1514ndash1524 2010
[33] J Wang Y Zhang S Xue J Wu Y Tang and L ChangldquoAssessment of spontaneous combustion status of coal basedon relationships between oxygen consumption and gaseousproduct emissionsrdquo Fuel Processing Technology vol 179pp 60ndash71 2018
[34] G L Duo D M Wang X X Zhong and B T Qin ldquoEf-fectiveness of catechin and poly (ethylene glycol) at inhibitingthe spontaneous combustion of coalrdquo Fuel Processing Tech-nology vol 120 pp 123ndash127 2014
[35] Y Xiao H-F Lu X Yi J Deng and C-M Shu ldquoTreatingbituminous coal with ionic liquids to inhibit coal spontaneouscombustionrdquo Journal of Aermal Analysis and Calorimetryvol 135 no 5 pp 2711ndash2721 2019
[36] X X Zhong D M Wang and X D Yin ldquoTest method ofcritical temperature of coal spontaneous combustion based onthe temperature programmed experimentrdquo Journal of ChinaCoal Society vol 35 pp 128ndash131 2010 in Chinese
[37] J Deng L-F Ren L Ma C-K Lei G-M Wei andW-F Wang ldquoEffect of oxygen concentration on low-tem-perature exothermic oxidation of pulverized coalrdquo Aermo-chimica Acta vol 667 pp 102ndash110 2018
10 Advances in Materials Science and Engineering
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
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