Mass transfer coefficients across dynamic liquid steel/slag ...
Estimates of the Chemical form of fluorine in Steel Slag by the … · 2016. 3. 11. · Fluorine...
Transcript of Estimates of the Chemical form of fluorine in Steel Slag by the … · 2016. 3. 11. · Fluorine...
Estimates of the Chemical form of fluorine in Steel Slag by the
application of saturated column test
Environmental Risk Analysis,
Kyoto University
Kengo NAKAMURA, Minoru YONEDA
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Steel Slag as Recycled Materials
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Back Ground
Oxidation Slag:70kg/t Reduction Slag:40kg/t
Recycled Materials ・Building material (Ex. Base course material)
・Cement raw material (Ex. Aggregate)
Fluorine regulated environmental standards in Japan
CaF2 Benefit: low temperature = low cost = Save energy
Environmental Standards Relating to use Steel Slag
Designated standard
Leachate Standard (㎎/L) Concentration Standard (㎎/kg)
0.8 4000
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Back Ground
Fluorine Environmental Standards
WHO : 1.5Fmg/L Ex. Sea : 1.3~1.7Fmg/L
The standard of fluorine addition will become trade between
the reduction of energy consumption and human health risk.
More Strict
Purpose in this study
• To determined chemical form of the fluorine that influenced or indicate the solubility of fluorine component by.
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Purpose
The method of estimate fluorine compounds is saturation column test
1. Dissolution fluorine trend from steel slag is reproduced through column test
2. PHREEQC fluorine compound is determined by comparing PHREEQC database
Sample (Oxidation slag, Reduction slag)
Oxidation slag Reduction slag O 36.09 O 46.85 Fe 18.81 Ca 29.75 Ca 15.59 Si 8.71 Si 8.69 Al 5.25 Al 6.73 Mg 3.84 Mn 5.29 C 2.55 Mg 3.15 S 0.71 C 1.32 Mn 0.27
Na 0.38 Fe 0.26
Ti 0.29 Ti 0.20 F 0.40 F 1.17
others 3.26 others 0.44
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Method
It is composed mainly of solid phase described above, quantities evaluation of solid phase in steelmaking slag has
not been achieved.
Saturation Column Test
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Method
Inflow
Outflow
Filter
Sample
Acryl Column
• The saturation column test is a method to estimate short term behavior of dissolution of element in solid recycled materials.
Condition
The final condition of column test will be achieved if the composition of Liquid (Solvent in liter) : solid (steel slag in kg) = 10 :1
Oxidation slag Reducing slag
Column height(cm) 30
Column bore(cm) 5
Solvent Ultra pure water Flow rate(mL/min) 19.6
Fill ration(g) 1264.39 699.96 Water content
rate(%) 0.06 2.8
Fill ration (Dry)(g) 1263.63 680.38
Density(g/ml) 3.96 3.2
Filling amount (Dry)(ml) 319.1 212.62
Porosity(%) 45.83 63.9
Results of Column Test Decrease of dissolution fluorine compounds, fluorine phase is transformed from high solubility phase to low solubility phase.
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Result
Oxidation Slag
Reduction Slag
Fluorine compounds are possible that it is seen not change due to the migration of solubility by water flow.
F Concentration : 3.6mg/L pH:10.4
F Concentration : 0.2mg/L pH:10.4
F Concentration : 2.2mg/L pH:11.6
F Concentration : 0.6mg/L pH:11.5
Chemical Equilibrium Model PHREEQC • Geosphere transition model PHREEQC is used to
calculate an ionic transfer as surface of aqueous and solid phase. Inorganic thermodynamic model in PHREEQC has been taken into account solid phase in the transition between the dissolution as well as an action of ion.
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Result
Example
Dissolution of the mineral fluorine(CaF2) CaF2 ↔ Ca2+ + 2F-
At equilibrium the aqueous concentrations obey the solubility product: Kfluorite = [Ca2+][F-]2 = 10-10.57 at 25℃ Relation can be rewritten in logarithmic form as: logKfluorite = log[Ca2+] + log[F-]2 = -10.57
Fluorine Components Name Reaction logK deltaH(kJ)
AlF3 AlF3 = Al+3 + 3F- -17.21 -34.04
Fluorite(CaF2) CaF2 = Ca+2 + 2F- -10.04 12.13
FeF2 FeF2 = 2F- + Fe+2 -2.38 -51.69 FeF3 FeF3 = 3F- + Fe+3 -19.24 -13.81
Sellaite(MgF2) MgF2 = 2F- + Mg+2 -9.38 -12.46
NaF NaF = Na+ + F- -0.021 -569
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Result
Fluorine component on the surface of steel slag
Calculation condition
Fluorine compounds are presented 0.1mol/kg and reappearance dissolution fluorine concentration on water 1L (density of water: 1g/cm3)
Relationship pH and pe of fluorine
compounds are created using PHREEQC
≡ 𝐴𝑙𝐹3 → 𝐴𝑙3+ + 3𝐹−
≡ 𝑁𝑎𝐹 → 𝑁𝑎+ + 𝐹−
≡ 𝑀𝑔𝐹2 → 𝐹𝑒2+ + 2𝐹−
≡ 𝐹𝑒𝐹3 → 𝐹𝑒3+ + 3𝐹−
≡ 𝐹𝑒𝐹2 → 𝐹𝑒2+ + 2𝐹−
≡ 𝐶𝑎𝐹2 → 𝐶𝑎2+ + 2𝐹−
Chemical Property of Fluorine Components
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Result
pH dependence pe dependence
CaF2, MgF2, FeF3 are showed pH dependence.
Fluorine compounds are not showed pe dependence except
FeF3.
In order to reproduce the fluorine trend in the column test, solvent conditions are used to measure the value of pH which was obtained from column test and chemical equilibrium computation.
Estimate of fluorine in steel slag by PHREEQC for calculating fluorine compounds
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Result
Parameter of column test are set at the same condition with PHREEQC (flowing amount water, water flow time, column height, sample density)
Each fluorine compound was calculated in each column. Fluorine compounds are assumed to present each fluorine compounds 100% in column
Oxidation Slag
Reduction Slag
AlF3, CaF2, FeF2, FeF3, MgF2, NaF (6 column)
AlF3, CaF2, MgF2 (3 column)
It is assumed that liquid solution condition is used same pH parameter of column test
(Oxidation slag: max pH10.4, Reduction slag: max pH11.8)
Estimate fluorine in steel slag by PHREEQC
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Result
Oxidation Slag
Reduction Slag
Conclusion
• Base on column test it can be conclude that fluorine concentration is high in initial condition which was rate of liquid : solid is 1 :1.
• In addition, from PHREQCE simulation (the relationship between dissolution concentration and fluorine dissolution rate) , it suggest that fluorine chemical compounds of oxidation slag are ALF3 and NaF .
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Conclusion
Oxidation Slag
Reduction Slag
• The decreased of fluorine concentration in reduction slag was lower compare with the decreased of fluorine concentration in oxidation slag.
• From PHREEQC simulation it can be showed that the chemical compound of fluorine in reduction slag is AlF3.
Thank you for your attention.
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Result
鉄鋼スラグ Iron slag
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生産量と利用量:Amount of production & utilization
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14107 13722
12168 1230212916
13427 1386514400
347 385 361 374 392317 342
452
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0
2000
4000
6000
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10000
12000
14000
16000
2000 2001 2002 2003 2004 2005 2006 2007
(t)
(t)
year
amount of production (Right) amount of recycle (Left)
Final waste disposal amount of accessory product Produce and recycle amount of steel slag *left: produce amount arbor right: recycle amount arbor
再使用
17,3%
道路
29,5%
地盤改
良材
5,2%
土木 35,6%
セメント
4,4%
コンクリート
骨材
0,3%
加工用
原料
2,4%
他利用
3,0% 埋立等
2,3%
製鋼スラグ
再使用
21,0%
道路
27,1%
地盤改良
材
5,5%
土木
37,3%
セメント
5,2%
コンクリート骨
材
0,0%
加工用原
料 0,3%
他利用
2,8% 埋立等
0,8%
転炉スラグ
再使用
1,6%
道路
39,4%
地盤改
良材
3,9%
土木
28,5%
セメント
1,0%
コンクリート
骨材
1,3%
加工用
原料
11,5%
他利用
4,0%
埋立等
8,8%
電気炉スラグ
Saturation Column Test
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Method
Oxidation
slag Reducing slag
Colume
height(cm) 30
Colume bore
(cm) 5
Solvent Ultra pure water Flow rate
(mL/min) 19.6
Fill ration(g) 1264.39 699.96 Water content
rate(%) 0.06 2.8
Fill ration
(Dry)(g) 1263.63 680.38
Density
(g/ml) 3.96 3.2
Filling
amount (Dry)(ml)
319.1 212.62
Porosity(%) 45.83 63.9