Group 3 Research project

Department of Mining and Materials Engineering

DUST CONTROL IN UNDERGROUND MINES

Literature Review Research Project

Course : MIME 422 Mine Ventilation

Instructor : Agus Pulung Sasmito, PhD

Semester : Summer 2015

Due date : Tuesday, June 23rd 2015

Group : 3

Members :

Geoffrey Doka

Yamac Ozdil

Myriam Jebali

Kin Hang Sham

Daniel Serrano Novikov

Thomas Xin Soong

Dust control Group 3

2

TABLE OF CONTENTS

Abstract.........................................................................................................3

Motivation.....................................................................................................3

Objectives.....................................................................................................3

Methodology.................................................................................................4

Background/ Introduction..............................................................................5

Impacts of dust.............................................................................................7

Dust monitoring.............................................................................................9

Dust mitigation and suppression technologies...........................................12

Computerized fluid dynamics and dust dispersion models

for dust control............................................................................................15

Innovation and future trends in dust control................................................18

Conclusion..................................................................................................23

Future outlook and recommendations........................................................23

References.................................................................................................24


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Abstract

This paper presents an introduction to dust control in the mining industry, with a special

emphasis on underground coal operations (where applicable). After a brief introduction to

mineral dust, including definitions, dust sources, dust classification and forces acting on a dust

particle, the impacts of dust on occupational health & safety and the environment are presented.

Going further, the importance of mine dust monitoring is highlighted through the analysis of dust

monitoring technologies and processes, with an in-depth look at the isokinetic sampling method,

mass concentration measurement, continuous real-time monitoring and personal dust

monitoring. Some of the dust mitigation and suppression technologies reviewed include foam

sprays and enclosed water spray systems. An insightful look is then given at computerized fluid

dynamics and dust dispersion models as the future for dust control, along with other innovations

such as ultrasonic dust suppression systems. The main motivation behind this literature review

paper are the occupational health & safety and environmental impacts of dust on the working

conditions of miners around the world.

Motivation

While initially the objective of this research project was to review air quality control in

underground mines, soon enough the research team discovered the width and depth for this

topic, which further motivated the team to narrow down the main topic to dust control in order to

present a concise and in-depth review of many facets related to dust in underground mining

operations. The main motivation to address this topic were all the health & safety and

environmental impacts of dust that have and are (albeit gradually less) affecting the working

conditions of miners around the world.

Objectives

• Introduce the topic of dust in mineral operations


4

• Define mineral dust

• Highlight the importance of dust control in underground mines

• Analyze the impact of mine dust on the environment and occupational health & safety

• Present dust monitoring technologies and techniques

• Review dust mitigation and suppression technologies

• Review current innovations and the future outlook for dust control in underground

mines

• Formulate recommendations for future developments in dust control

Methodology

This research project was undertaken as a scientific literature review, with the main

focus of reviewing recent (>1993) peer reviewed technical articles on dust control related topics.

Preference was given to technical articles found in engineering journals. Where applicable,

preference was given to papers referring to underground mines with emphasis on coal mining.

The research project was split into six inter-related sub-topics each treating a different

aspect of dust control in the mining industry - one aiming to provide an introduction and

background to mineral dust, another one treating the impacts of dust on occupational health &

safety and the environment, dust monitoring, dust mitigation and suppression technologies,

computerized fluid dynamics and dust dispersion models for dust control and the final one

devoted to innovation and future trends in dust control, respectively.

Initial stage of work on the research project implied each research team member

performing an independent research towards the selection of their sub-topic of interest along

with further consultation with the research team through periodic meetings. These research

team meetings allowed to outline and shape the general direction of the research, allowing

further collaboration between the research team members. Final editing and review being a joint

team effort.


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Background/ Introduction

Particulate emissions, such as dust, affect all types of mining activities. These emissions

are created through a range of processes encompassing from blasting through transportation,

sample preparation, processing and handling. Research has confirmed that dust can be

potentially hazardous to human health, the environment, the working conditions as well as the

productivity of the mine [1] [2].

A generic definition used for dust describes fine particles that are suspended in the

atmosphere. A more formal definition is given by the International Standardization Organisation

(ISO), where dust is defined as “small solid particles, conventionally below 75 microns in

diameter, which settle out under their own weight but which may remain suspended for some

time”. Any type of disturbance of fine particles derived from soil or rock derived from mining

activities results in the release of particulates into the atmosphere. Mine dust consists mainly of

particles from exposed soil and rock, which makes the nature of its composition less complex

than in other types of dust [1].

[1] sub-classified dust with respect to its environmental, occupational health and

physiological effects (Figure 1).

In general, dust habitually emanates from larger masses of the same material through

any type of physical rupture processes. In mines, particulate emissions can be released

throughout a range of site preparation, stockpiling, loading, transportation and mineral

Figure 1. Dust classification [1]


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processing operations [2]. The type of dust released depends on its material properties, such as

hardness, particle size distribution, density and moisture and by process constraints, such as

physical rupture process, drop from elevation, solid mass flow rate, amount of handling and

energy consumed in the process.[1] [2].

Table 1. Dust sources in mineral sites [1]

Since there are diverse processes acting on different sized dust particles, the resulting

behaviour of dust is quite complex. Air dynamics dictate that for a dust particle to become

airborne it must have an aerodynamic drag force larger than the sum of the particle weight and

the inter-particle forces. An additional challenged pointed out by [1] is that “smaller particles will

behave as a gas and they will be influenced by molecular forces, while larger particles will be

affected by gravitational and inertial forces”[1].

Other important properties for describing the behaviour of dust are the chemical

composition, mass concentration, density, particle size and shape of the dust particles. The

main forces acting on dust particles are gravitational settlement, Brownian motion, eddy

diffusion and agglomeration. Main one being the gravitational settlement due do the relative

ease of control on this force (e.g. by wetting), since other forces such as Brownian forces being

more difficult to control. The gravitational forces applied to dust particles will tend to let the dust

settle under its own weight. Other important processes affecting dust behavior include

compaction, re-entrainment and deposition. [1] [2].

Dust control

Impacts of dust

The adverse influences of dust are mostly related to human health and the environment.

Nonetheless, safety and productivity might also be influenced by high concentrations of dust.

Coal dust is a fine powdered form of coal, which

pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining,

transportation, or by mechanically handling coal.

Effects of dust on human health and possible

Dust is one of the largest work-

‘‘killers’’ through the years. Whenever materials are handled or broken down, dust is liable to be

produced. At this part we will examine the occupational health hazards

exposure to respirable coal mine dust over a working lifetime.

Exposure to any dust in extreme quantities can create breathing difficulties. Dust is one of the

main disasters during the coal production. Coal Workers' Pneumoconiosis (CWP) i

disease that results from breathing in coal dust over a long period of time. Several factors

increase a person's risk of developing pneumoconiosis such as the concentration of respirable

coal dust, coal dust particle size and its composition, free

duration of contact, age, work environment and work practices of workers

Table 2 - Workplace risk classification in accordance with threshold limit values in the Turkish dust

regulation

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Coal dust is a fine powdered form of coal, which is created by the crushing, grinding, or


transportation, or by mechanically handling coal.

Effects of dust on human health and possible controls

-related hazards and it has been one of the largest occupational


produced. At this part we will examine the occupational health hazards

exposure to respirable coal mine dust over a working lifetime.


main disasters during the coal production. Coal Workers' Pneumoconiosis (CWP) i



coal dust, coal dust particle size and its composition, free silica content (quartz minerals), the

duration of contact, age, work environment and work practices of workers

Workplace risk classification in accordance with threshold limit values in the Turkish dust

Group 3



is created by the crushing, grinding, or


related hazards and it has been one of the largest occupational


associated with


main disasters during the coal production. Coal Workers' Pneumoconiosis (CWP) is a lung



silica content (quartz minerals), the

Workplace risk classification in accordance with threshold limit values in the Turkish dust


8

To manage the coal dust, a number of approaches have been broadly used. The most popular

technologies are ventilation, water spray, foam, water/wetting agent spray and dust collecting

fan. Ventilation is key to any underground operating mine no matter the mineral being extracted.

Maintaining good health, more importantly lives, of miners depends on the constant cycle of

venting in fresh air and flushing out contaminated air. One of the most common safety

precautions that most mining engineers are focused on is increasing ventilation efficiency in

underground mines. This is because CWP is the result of inhaling coal dust particles that lurk in

the air. If an underground mine has mastered the science of ventilation efficiency then the

amount of airborne dust particles will decrease and ultimately, decrease the chances of the

mine’s employees being diagnosed with Pneumoconiosis. Foam technology for dust control is

another method that gained attention in the recent years. The dust wettability is improved

quickly, as a result, the dust is wetted very efficiently. Moreover, the adhesiveness of foam is

very strong. Once the foam and dust collide, the dust adheres to the foam quickly and firmly.

Thereby, it catches the dust particles much more easily.

Impacts on the environment

As the requirement for fossil fuels and mineral resources continues to raise worldwide, the

impact of mining will be increasingly important in the field of environmental disciplines.

The dust on the floor can be a hassle on productivity, but it can also affect the ecology and

agriculture of a region. Surface dirt irritation is determined by the color contrast between the

accumulated dust and '' clean '' area of the surface before colonization, public opinion and other

special features of the area.

The consequences of dust in agriculture and ecology of an area is determined by the

concentration of dust particles in ambient air, their size distribution, the rate of deposition and

chemistry. These factors can affect soil chemistry and plant health of the surrounding

microclimate weather and local conditions, as well as the penetration of dust on vegetation. In


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addition to the vegetation, dust deposition may affect the bonds and forests animal

communities.

Effects on safety and productivity

Dust might disturb safety at work leading to reduced perceptibility in the workplace and keeping

in mind the value of such concentrations uneasiness should not be underestimated. In addition,

certain powders, from coal and sulfide ores can cause bursts. The dust explosiveness differs on

five main strictures. These are the presence of combustible dust in a form provided finely

availability of oxidant, the presence of an ignition source, a certain degree of confinement and a

state of mixed reagents. The chemical composition of powder, particle size and shape, surface

area and moisture content are also very important variables.

Dust can also minimize productivity and product damage. It sticks in machinery and products

reducing the life cycle of the equipment and the modification of the properties of raw materials.

Dust monitoring

Demand for monitoring of aerosols and dusts in mining industry is increasing under

recent health, safety and environmental regulations. Collected data helps evaluating dust

generation and controlling of combustible and toxic coal mine dust as well as particulate matter

generated from diesel engines to minimize mine accidents. In current mining industrial

operations, the most common sampling and monitoring techniques are isokinetic sampling

method, mass concentration measurement, continuous real-time monitoring, and personal dust

monitoring.

Isokinetic sampling method

Isokinetic sampling method is to obtain dust samples independent of particles size from

a moving stream with constant velocity, in other words, the sample taking velocity is the same


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velocity as the main stream. Gas velocity at the probe nozzle inlet is critical in this method and

has to be determined, in order to maintain isokinetic conditions and evaluate the volumetric flow

rate in airway, which helps identify the dust emission rate. If the sample taking velocity is

smaller than main stream velocity, heavy particles located on a flow line that passes by the

probe can enter the probe; on the other hand, if the sample taking velocity is too high, heavy

particles can go past the probe instead of being collected. One of the recent techniques to

obtain accurate gas velocity is using pressure-balance-type dust sampling probe which

balances the pressure difference between the inner and outer surfaces of the probe head, and

provide an uncertainty less than 1.9% for velocities in the range 5–35 m/s.[1]

Still air sampling method is similar to isokinetic sampling method, but it collects samples

from still air and mainly concerns with the settling velocity (a.k.a. terminal velocity) and inertia of

the particles.

Mass concentration measurement

Mass concentration measurement can be categorized into direct or indirect method.

Direct method is using gravitational force to measure dust mass concentration, which is called

gravitational analysis. One of the example is measuring aerosol mass concentration

gravimetrically using glass fiber filters. The other method measures mass concentration

indirectly and the results are inferred based upon calibration. Yet indirect method is more

common used. Optical scattering, an indirect method that detects the scattered light intensity to

measure dust concentration in air, is a widely used measurement techniques because of its

simple and inexpensive appliance. The angle at which the instruments measured can vary from

12° to 90°, however, a study shows that the range of 15° to 30° can provide a higher degree of

accuracy. Most instruments use a light source with a wavelength in the vicinity of 900 nm. The

combination of light source wavelength and measurement angle cause some devices become

sensitive to particle size, whereas some are sensitive to chemical composition. Most method of


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calibration depends on these dust characteristics, and hence can yield inaccurate

determinations of mass concentration.[2]

Continuous real-time monitoring

Traditional gravimetric approach to mass measurement has inherent delay and not

allows to provide instant on-site quality control. In order to improve monitoring and control of

coal mine dust, continuous real-time monitoring is developed. Monitors, which are usually

mounted on mining operators, continuously sample dust in underground working area and

provide real-time measurement. The sensor technologies for continuous monitoring include beta

gauges, light attenuation, TEOM (Tapered element oscillating microbalance), piezo-electric

microbalance, light scattering and electrical mobility. Same as indirect mass concentration

method, some sensors measure property of the particles other than their mass and convert

reading to equivalent mass based on implied assumptions about the relationship between

particles mass and their properties, which can lead to inaccurate determination. Nonetheless, a

study shows that microbalance instruments (such as TEOM and piezo-electric microbalance),

which sense the change of frequency of oscillator due to additional weight from particles, are

more desirable continuous real-time monitor because they measure aerosol mass directly and

well operate in various underground environment. [3]

Personal dust monitoring

The philosophy behind personal dust monitoring (PDM) is to measure workplace

respirable dust concentration in order to eliminate health hazard to miners caused by over

exposure to dust. The recent personal dust monitor is integrated into the cap lamp of miner that

can continuously sample dust and provide measurement of dust concentration in breathing

zone. Likewise of traditional personal sampler, PDM requires a multiplier to convert reading to

standard criterion. A research compared PDM and personal samplers indicates that there is a

strong linear regression between two methods. The suitability of PDM in access to respirable


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dust concentration and direct reading suggest PDM is a superior sampling device to personal

sampler with a smaller multiplier.[4]

Dust mitigation and suppression technologies

There are techniques in practice today used to suppress dust and to minimize the generation of

dust. Some widely used techniques are through ventilation, dust-collecting fans, water infusion,

water spray and foam spray. This report will be discussing the application of foam spray, water

spray, and water infusion.

Foam application - technology

In convention, water spray has been one of the main dust suppression techniques.

However this method has presented difficulties in the ability of suppressing dust, specifically

with combination of dust diffusivity and water surface tension. The surface tension of water

permits it to flow in “droplet” form, and regardless the fineness of the droplet, there will still be

tiny empty cavities for dust to escape through (R. Wanxing, 2014). Simply put, foam technology

solves this problem by reducing the surface tension of water. With the addition of high

expansion foam water is able to smother a greater amount of area with the same amount of

water and increase the adhesion capability (Q. Wang, 2015).

According to the paper written by R. Wanxing, W. Deming, G. Qing, Z. Bingzhao there

are three key components of foam technology: foaming agent, foam generator, and the foam

flow. The presence of the foam agent results in a decrease in the surface tension of water,

allowing for a more continual flow. It was found that a foam agent concentration of 0.5 % is the

optimal solution. Next, the foam is produced by the foam generator. The foam generator can be

similarly thought of as the theory of a turbulent jet as it takes advantage of high pressure water

and compressed air. Firstly, the high-pressure water flow is passed through a jet nozzle to


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convert the water flow to high-velocity turbulent flow, which naturally and proportionally draws

ambient air and foaming agent into the mixing chamber (Q. Wang, 2015). Next, the swirler

accelerates the mixing of air and liquid to aid in high quality foam generation, and is forced

through meshing at the outlet to produce foam. For better understanding, Figure 2 illustrates the

internal process of a foam generator.

Figure 2: Foam Generator

Limitations. To make full use of the foam and for best practice it is important that the shape of

the foam flow is similar to the shape of the dust source (R. Wanxing, 2014). Also, an inadequate

level of pressure of the compressed-air supply can negatively affect foam generation (Q. Wang,

2015). With that being said, in comparison with simple water spraying, foam technology has

proven itself to increase total dust suppression efficiency by 45% (R. Wanxing, 2014).

Enclosed Water Spray Systems

In underground coal mine operations today, falling bulk systems (i.e. conveyance systems) are

major dust producers. Figure 3 presents the concept of how dust is generated over a

conveyance system and how water spray systems are installed to suppress dust production.

Dust control

\

Figure 3

Technology. The water spray system utilizes two aspects of dust suppression by preventing

generation and suppressing generated dust (Faschingleitner

represents the efficiency of the primary suppression stage where the bulk material is moistened

before it transitions on to the bottom conveyor. Additionally, n2 represents the efficiency of the

secondary suppression stage where dust created through the diffusion process is suppressed.

As the system is connected in series the overall efficiency can be expressed as such:

From tests conducted in Mr. Faschingleitner’s paper it was found that the position of the

nozzle is a key factor in dust suppression and there is potential to have inefficient nozzle

locations. Moreover, to increase the potential in dust suppression numerous nozzles can be

utilized over a broad range with sprays at low water consumption rates (Faschingleitn

14

3: Dust Generation Model and Conveyance

The water spray system utilizes two aspects of dust suppression by preventing

generation and suppressing generated dust (Faschingleitner, 2011). In Figure



where dust created through the diffusion process is suppressed.



ey factor in dust suppression and there is potential to have inefficient nozzle


utilized over a broad range with sprays at low water consumption rates (Faschingleitn

Group 3

The water spray system utilizes two aspects of dust suppression by preventing

, 2011). In Figure 3 above, n1



where dust created through the diffusion process is suppressed.



ey factor in dust suppression and there is potential to have inefficient nozzle


utilized over a broad range with sprays at low water consumption rates (Faschingleitner, 2011).


15

With this in mind, each system has its own specific characteristics and cannot be necessarily

optimized from experimental values from a journal article. What is most important to take away

from this paper is that suppression efficiencies can be optimized if the spacing between the

nozzles is small enough to block particle flow between nozzle sprays (Faschingleitner, 2011).

Limitations. There are limitations with this method, the main concern being water consumption.

This process does require heavy water flow and it should be clean water. Any impurities or

unwanted particulates can contaminate coal and potentially throw off plant processing. Another

limitation to this method is that spray nozzles can experience blockages from material (dust)

build up and reduce flow efficiency.

Computerized fluid dynamics and dust dispersion

models for dust control

Over the past decade, the use of computational modeling has been more prominent to further

develop the studies of fluid flow in a ventilation system. Modeling turbulent flow can prove to be

difficult, and therefore it is important that turbulence models be compared to experimental data

to determine which model best represents experimental data. Sometimes experimental data is

unavailable such as in deep mines where experimental investigation is difficult because of

Figure 4 - Velocity contours demonstrated using various turbulence models.


16

safety concerns. Therefore, mathematical and computational modeling is essential for

designing, maintaining, and optimizing an underground mine. The Spallart-Almaras model was

deemed the most appropriate out of the models in Figure 4 to model

fluid flow. The authors continued by modeling six different flow scenarios to determine which

would yield in the highest air velocity as this closely correlates to higher methane removal and

lower concentrations, but also which will maintain the lowest pressure drop to ensure low

operating costs. It was concluded that although serpentine stopping demonstrated the highest

air velocity, it’s requirement of a high pressure drop to push the flow, made partial stopping

more attractive as it’s air velocity was comparable to that of serpentine stopping, but the

pressure drop is significantly lower. The flow distribution at the cross-cut region was also

analyzed as it is where methane concentrations are usually the highest and therefore of

greatest risk to miners. From simulations of various scenarios, it was found that brattice-

exhausting ventilation is the best performing as it has a low-pressure drop and good methane

removal. Therefore, it can be concluded that in an underground coal mine, the Spallart-Almaras

model is best representative of fluid flow, and partial stopping with brattice-exhausting

ventilation at cross-cuts is favorable [1].

Candra et al. studied mitigation of dust through the simulation of ventilation in an underground

room and pillar coal mine using computational fluid dynamic approach to determine which

ventilation method is most effective. The discrete phase model is used to represent dust

movement, and this time, the k-Epsilon model is deemed as a suitable representation of

turbulent flow. Using this model, simulations of air velocities and dust concentrations are

produced as displayed in Kurnia et al. article. From these results and a graph showing the

distance from mining face as compared to the dust concentration, it can be concluded that the

non-auxiliary system mitigating dust most efficiently is the brattice system, while the auxiliary

system with the best dust handling characteristics is the brattice-exhaust system. Therefore, the


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brattice ventilation system is preferred for dust control and mitigation in underground coal

mining [2].

While the previous articles analyzed constant inflows of air, this article analyzes varying

conditions such as advance of the roadheader or when coal characteristics change. Also,

unlike the CFD models in the previously mentioned articles, these ones could be compared to

experimental data collected at the Carbinar coal mine located in Asturias, Spain. This provided

experimental data to validate the predicted CFD results. Two auxiliary systems were present:

one with a forcing duct with an airflow of 1.5 m3/s and an exhausting fan with an airflow of 6.5

m3/s, both hung on the roof, which we will term auxiliary system E-R, and the other with the

same flow specifications but with the forcing duct on the roof and the exhaust on the floor, which

will be termed E-F. The Computational Fluid Dynamics Ansys CFX 10.0 commercial software

was used to display the multiphase flow behavior. The k-epsilon turbulence model was chosen

after demonstrating the best linear regression of the models as compared to experimental data.

The Lagrangian Tracking model was used on Ansys to calculate the equation of particle

trajectory, and the simulation calculations were completed by iterations, which delivered a

solution when convergence was achieved. From the graphs displaying the evolution of

concentrations as distance changes according to both CFD modeling and experimental data, it

can be seen that CFD modeling is consistent with experimental data and that both systems

have similar efficiencies except between the face and the 3 m cross section where the E-F

system is significantly more efficient in diluting concentration. Studying Figure 5, which displays

the evolution of dust concentration and airflow velocity in the presence of the roadheader, it can

be concluded that the E-F system has lower dust concentrations due to the fact that there is

higher airflow in the first 6 meters of the roadway. Although, the airflow velocity of the E-F

ventilation system decreases as it approaches the face, the dust concentration continues to

decrease because the dust is captured by the exhausting ventilation. Therefore, it can be


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concluded, that the most effective modification was to increase the air flow velocity and modify

the height of the duct from the floor [3].

Figure 5 - Evolution of concentration and airflow velocity at point 2

Innovation and future trends in dust control

Conventional dust control methods such as water infusion, water spraying, chemical agent

spraying and negative (exhausting) mine pressure have been used in underground coal mines

to protect the life and health of coal mine workers. However, there are drawbacks and

limitations in these control methods. [1] For example, water infusion has difficulty in keeping up

with large scale operations and spraying nozzles can be blocked. Chemical agent spraying is

expensive and may pollute the soil.

To improve the effectiveness and lower the cost of conventional dust control methods, some

experimental dust control methods are reviewed.

Foam-sol-based Coal Dust Control

The current foam-based dust removal is only effective to suppress dust for a short period of

time. Dust can raise again after the foam is dried. The foam-sol-based dust control method


19

aims to resolve this drawback. Foam-sol is produced in a slow crosslink reaction of grease,

acetate and byproduct. [1]

There are three major advantages of foam-sol dust control:

1. Dust capture: It possess high surface viscosity and long-lasting moisture

2. Dust suppression: It can bind dust onto surface and prevent fugitive dust from escaping

even after air drying, due to its high cohesiveness.

3. Dust isolation: Due to its high viscosity and elasticity, it can be sprayed onto conical

surface. It will hold the regional dust and keep it from flowing outwards.

The following photos shows the effects of aqueous foam and foam-sol methods on coal dust:

Figure 6: Coal dust sample covered by foam-sol and aqueous foam [1]

Figure 7: Effect of foam-sol and aqueous foam after air drying [1]


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Figures 6 and 7 shows the experimental foam-sol generating system. [1] The compressed air

and suction pump are used as its major and minor power source. The outlet sprays out the

foam-sol through a conical-shaped diffuser (Figure 8) onto the dust source.

The shape of foam flow should be similar to the shape of dust source. [2] The design of the

diffuser allows the nozzle to have a circular spraying range (Figure 9) which make the covering

of dust source more efficient. [2] The foam-sol can enclose the dust source and keep it isolated.

Figure 8: Schematic of foam-sol generating system [1]

Figure 9: Foal-sol generating system prototype [1]


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Figure 10: Special conical nozzle used for foam-sol [1]

Figure 11: Spraying demonstration [1]

Although foam-sol has a lower wettability than aqueous foam solution but it can penetrate the

cracks of coal dust and fill the pores between particles to bind them firmly. Due to its high

viscosity, cohesiveness, and low volatility, it has a higher performance in dust control (capturing

dust and suppress fugitive dust).

Ultrasonic Dust Suppression System


22

From existing water spraying system in coal mines, it can be concluded that smaller water

droplets are more effective in removing floating dusts. The ultrasonic dust suppression system

can produce micro-sized water droplets with compressed air and water to effectively suppress

the dusts. [3] The theory of this system is that the probability of contact with dust particles

increases as the size of water droplets decreases.

The spraying nozzles is shown in Figure 12. The inflow compressed air is accelerated through a

converging nozzle and expands into a diverging section. [3] This produces a strong shock wave

that shatters the water into micro-sized droplets.

Figure 12: Ultrasonic atomizing nozzle [3]

The main advantage of ultrasonic dust suppression are that it generates a less atmospheric

pollution and consumes less water. The future trends of improving dust control techniques in

this case could be modifying the design of spraying nozzles for foam or micro water droplets.

Design for the environment should always be considered in the design process.


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Conclusion

While this research paper only touched on some aspects of dust control in the mining industry, it

was a humbling experience to discover the depth and complexity of a topic that might not be

given great importance overall in the design of ventilation systems in underground mines. It is

clear, non-the-less, that in order to ensure the effectiveness of the mine's ventilation system

along with an increased control of air quality in an underground mine that, that a dust control

and monitoring plan needs to in place, incorporating some, if not all of the technologies,

procedures and techniques outlined in this research paper. There is great room for continuous

work in this direction, which is further considered in the "Future outlook and recommendations"

part of this report.

Future outlook and recommendations

Even though great advancement has been made throughout the years towards the monitoring,

control and suppression of mineral dusts, there is still a great room for further improvements

and academic research in this topic. Novel technologies such as the application of computerized

fluid dynamics and dust dispersion models hold great promise for improving our understanding

of dust generation and propagation. As shown in this research paper, the application of these

models in active mining operations can greatly improve the overall efficiency of the ventilation

systems with a great potential of application for dust control. There is hope for an increased

cooperation between academia and industry to work towards this end. Other innovations such

as the ultrasonic dust suppression systems and the foaming reagents added to water sprays

have proved to be effective to mitigate and suppress the propagation of dusts, but have yet to

be tested on a bigger scale and applied, along with more effective dust monitoring technologies,

in order to prevent dust being an occupational hazard in underground mines around the world.


24

Finally, while the aspect of cost has not been considered in this study, the widespread

application of the dust mitigation and monitoring technologies presented in this paper and

beyond, will be further enabled by sound engineering design and large-scale production of such

technologies, which should reduce their overall cost.

References

Background/ Introduction

[1] E. Petavratzi, S. Kingman, I. Lowndes, Particulates from mining operations: A review of sources,

effects and regulations, Minerals Engineering, Volume 18, Issue 12, October 2005, Pages 1183-

1199, ISSN 0892-6875, http://dx.doi.org/10.1016/j.mineng.2005.06.017.

[2] R.J. Hamilton, Chapter 14 - Dust control in the mining industry, In International Series of

Monographs in Heating, Ventilation and Refrigeration, edited by R.G. DORMAN, Pergamon,

1994, Pages 531-550, Dust Control and Air Cleaning, ISBN 9780080167503.

Impacts of dust

[1] Ilknur Erol, Hamit Aydin, Vedat Didari, Suphi Ural, Pneumoconiosis and quartz content of

respirable dusts in the coal mines in Zonguldak, Turkey, International Journal of Coal Geology,

Volumes 116–117, 1 September 2013, Pages 26-35, ISSN 0166-5162

[2] Wanxing Ren, Deming Wang, Qing Guo, Bingzhao Zuo, Application of foam technology for dust

control in underground coal mine, International Journal of Mining Science and Technology,

Volume 24, Issue 1, January 2014, Pages 13-16, ISSN 2095-2686


25

[3] P.C.S. Coelho, J.P.F. Teixeira and O.N.B.S.M. Gonçalves, Mining Activities: Health Impacts, In

Encyclopedia of Environmental Health, edited by J.O. Nriagu, Elsevier, Burlington, 2011, Pages

788-802, ISBN 9780444522726

Dust monitoring

[1] Szulikowski, J. and P. Kateusz, Measuring gas velocity in a duct as a specific function of a

pressure-balance-type probe in an isokinetic dust sampler. Environmental Technology, 2009.

30(3): p. 301-311.

[2] Litton, C.D., Studies of the measurement of respirable coal dusts and diesel particulate matter.

Measurement Science & Technology, 2002. 13(3): p. 365-374.

[3] Cantrell, B.K., et al., Continuous respirable Mine Dust Monitor Development. Proceedings of the

6th International Mine Ventilation Congress, ed. R.V. Ramani. 1997. 11-17.

[4] Page, S.J., et al., Equivalency of a personal dust monitor to the current United States coal mine

respirable dust sampler. Journal of Environmental Monitoring, 2008. 10(1): p. 96-101.

Dust mitigation and suppression technologies

[1] R. Wanxing, W. Deming, G. Qing, Z, Bingzhao, Application of Foam Technology for Dust Control

in Underground Coal Mine, International Journal of Mining Science and Technology 24 (2014)

13-16, DOI:10.1016/j.ijmst.2013.12.003.

[2] Q. Wang, D. Wang, H. Want, F. Han, X. Zhu, Y. Tang, W. Sei, Optimization and Implementation

of a Foam System to Suppress Dust in Coal Mine Excavation Face, Process Safety and

Environmental Protection 96 (2015) 184-190, DOI:10.1016/j.psep.2015.05.009.


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[3] J. Faschingleitner, W. Hoflinger, Evaluation of Primary and Secondary Fugitive Dust

Suppression Methods using Enclosed Water Spraying Systems at Bulk Solids Handling,

Advanced Powder Technology 22 (2011) 236-244, DOI:10.1016/j.apt.2010.12.013.

Computerized fluid dynamics and dust dispersion models for dust control

[1] J.C. Kurnia, A.P. Sasmito, A.S. Mujumdar, CFD Simulation of Methane Dispersion and

Innovative Methane Management in Underground Mining Faces, Applied Mathematical

Modeling 38 (2014) 3467-3484, DOI:10.1016/j.apm.2013.11.067

[2] A.P. Sasmito, E. Birgersson, H. Ly, A.S. Mujumdar, Some Approaches to Improve Ventilation

System in Underground Coal Mines Environment – A Computational Fluid Dynamic Study,

Tunnelling and Underground Space Technology 34 (2013) 82-95,

DOI:10.1016/j.tust.2012.09.006.

[3] J. Torano, S. Torno, M. Menendez, M. Gent, Auxiliary Ventilation in Mining Roadways Driven

with Roadheaders: Validated CFD Modeling of Dust Behaviour, Tunnelling and Underground

Space Technology 26 (2011) 201-210 , DOI:10.1016/j.tust.2010.07.005

Innovation and future trends in dust control

[1] Z. Xi, M. Jiang, J. Yang, and X. Tu, "Experimental study on advantages of foam–sol in coal dust

control," Process Safety and Environmental Protection, vol. 92, pp. 637-644, 11// 2014.

[2] Q. Wang, D. Wang, H. Wang, F. Han, X. Zhu, Y. Tang, et al., "Optimization and implementation

of a foam system to suppress dust in coal mine excavation face," Process Safety and

Environmental Protection, vol. 96, pp. 184-190, 7// 2015.


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[3] Y.-s. Xie, G.-x. Fan, J.-w. Dai, and X.-b. Song, "New Respirable Dust Suppression Systems for

Coal Mines," Journal of China University of Mining and Technology, vol. 17, pp. 321-325, 9//

2007.

Group 3 Research project

Documents

Transcript of Group 3 Research project