Dust Control Technology Research Articles

Threshold Determination for Effective Water Injection in Coal Seams: Insights from Numerical Simulation

Coal seam water injection is the most basic and effective dust control technology used on the coal mining face. Numerical simulations are helpful for predicting the humidity range of coal seam water injection. The results can provide guidance for the field design of coal seam water injection process parameters. In order to understand the influence of coal seam water injection pressure and water injection time on the coal seam wetting effect, this paper uses the Fluent 17.0 software system to study the process parameters of the coal seam water injection seepage process under different conditions. It is found that in the process of coal seam water injection, with the increase in water injection pressure and the prolongation of water injection time, there is a specific threshold value for the change in coal seam permeability. Only when the water injection pressure and time increase to the threshold value will the permeability of the coal seam be significantly enhanced and the wetting effect improved. The pressure threshold of the mine is 15 MPa–20 MPa, and the time threshold is the first 42 h.

Effect of physicochemical properties on critical sinking and attachment of respirable coal mine dust impacting on a water surface

Respirable coal mine dust (RCMD) inhalation is identified as the main cause of the resurgence of coal worker’s pneumoconiosis (CWP) since the mid-1990s. At present, the predominant dust control technology is the water spray system. However, in practice, the capture efficiency of RCMD by this technology is relatively low. To understand the capturing mechanism and develop improvement strategies, this research is focused on the surface chemistry study of RCMD and its impact on a water surface using a dynamic model. Proximate analysis, chemical, and mineral composition of a run-of-mine (ROM) coal sample from Appalachian region were analyzed using a proximate analyzer, Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and X-ray Diffraction (XRD), respectively. Contact angles were measured by capillary rise test using the Washburn equation. Based on the dynamic model, the effects of particle size, density, contact angle, and surface tension on the critical sinking were investigated. It was pointed out in this work that reducing surface tension, in turn, decreases contact angle, which has been neglected in the literature. Regime maps for different minerals were created and showed that organic matter has the highest critical velocity due to its low density and high contact angle. Reducing water surface tension to the critical solid surface tension of coal around 30 mN/m could maximize the attachment efficiency. Scaling laws, constructed by force balance, led to the criteria of critical sinking: Ucr∼61-cosθ2D+1γlvρlR, i.e., Wecr∼121-cosθ2D+1. A semi-empirical formula for critical velocity was obtained by fitting the simulation data, Ucr=1.0961-cosθ2D+1γlvρlR. Attachment efficiency was defined and formulated as Pa=U02Ucr2=We0Wecr, establishing relationships between attachment efficiency and the physicochemical properties of RCMD and water droplets.

Research on dust control technology and numerical simulation of conical guiding air curtain in fully mechanized excavation face

The dust pollution caused by the operation of fully mechanized heading face poses a serious threat to the safety production of operators and working face. To reduce dust concentration at the fully mechanized heading face, this study analyzed dust samples collected from various positions to understand the particle size distribution characteristics. Based on these findings, a conical diversion air conditioning (CDAC) device was designed to create a radial air curtain for dust control in the roadway cross-section. Computational Fluid Dynamics (CFD) was then employed to investigate the airflow and particle dynamics when the cone-shaped deflector was in closed and open states. The results show that in the fully mechanized heading face, the dust distribution in the working area of the roadheader driver is relatively dense, and the dust particles with particle size ≤ 8 μm account for a large proportion. When the CDAC device is deployed, the axial airflow in the roadway is changed into a rotating airflow along the roadway wall, and an air screen is established in the working area of the roadheader driver to block the outward diffusion of dust. When the pressure air outlet is arranged 30 m away from the tunneling head, the pressure air volume is set to 400 m3/min, and the CDAC device can better form the air curtain barrier to block the dust particles. It provides a new method for effectively controlling the dust concentration of the fully mechanized heading face and directly ensuring the health of the roadheader driver.

Law of respirable dust pollution induced by cutting-advancing support in a fully mechanized mining face and spatial stereoscopic dust control and removal technology

Law of respirable dust pollution induced by cutting-advancing support in a fully mechanized mining face and spatial stereoscopic dust control and removal technology

Review on Dust Control Technologies in Coal Mines of China

China faces a challenge in the sustainable development of the coal industry due to pneumoconiosis problems. Dust control technologies are crucial for safe production and miners’ health, ensuring the industry’s longevity. This article reviews the development process of dust prevention and control in underground coal mines in China, summarizes various technologies, and divides them into dust suppression, open-space dust reduction, and mine dust collectors according to different stages and environments of use. In dust suppression technologies, coal-seam water injection can reduce total dust generation by 60%, wet rock drilling can reduce drilling dust in the presence of stable water sources and high-pressure bearing equipment, and water-seal blasting can reduce blasting dust by 50–70%. In open-space dust reduction technologies, spray dust suppression can remove total dust by 50–95% and the removal efficiencies of foam dedusting for total and respirable dust are reported to reach 95% and 85% under the right conditions, respectively. In dust collector technologies, dry collectors can remove 80–95% of total dust. Wet collectors achieve up to 90% efficiency, dependent on water supply and waste processing. This article also discusses vapor heterogeneous condensation technology as a promising method for improving respirable dust removal in humid mine environments.

Effects of dust controls on respirable coal mine dust composition and particle sizes: case studies on auxiliary scrubbers and canopy air curtain

Control of dust in underground coal mines is critical for mitigating both safety and health hazards. For decades, the National Institute of Occupational Safety and Health (NIOSH) has led research to evaluate the effectiveness of various dust control technologies in coal mines. Recent studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains (CACs) to reduce respirable dust in key operator positions. While detailed dust characterization was not a focus of such studies, this is a growing area of interest. Using preserved filter samples from three previous NIOSH studies, the current work aims to explore the effect of two different scrubbers (one wet and one dry) and a roof bolter CAC on respirable dust composition and particle size distribution. For this, the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive X-ray. Results indicate that dust composition was not appreciably affected by either scrubber or the CAC. However, the wet scrubber and CAC appeared to decrease the overall particle size distribution. Such an effect of the dry scrubber was not consistently observed, but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return air. Aside from the insights gained with respect to the three specific dust control case studies revisited here, this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.

Numerical simulation of the dust pollution characteristics and the optimal dustproof air volume in coal washing plant screening workshop

Dust pollution generated during the working process of a screening workshop in a coal washing plant seriously threatens the occupational health of workers. To improve the working environment for workers, we investigated the effects of various airflow parameters on the diffusion of dust particles and pollutants. We established a proportional model of the screening workshop and conducted spatiotemporal analysis of the evolution laws of airflow and particulate matter. We used numerical simulation and on-site measurements to obtain the optimal dust removal air flow rate in a coal washing plant workshop. When the air flow rate is between 360 and 1260 m³/min, the overall dust concentration in the workshop and the average dust mass concentration in the breathing zone decrease significantly as the air flow rate increases. However, if the air flow rate is too high, this can cause re-entrainment of dust, which will pollute the operation area again. The optimum dust removal airflow for the inlet air was 1260 m³/min. This air flow rate decreases the dust at the height of the breathing zone in the working area, and the dust concentration at the sidewalk in the working area decreases by 58.82%. This air flow rate can act as a reference value for workshop ventilation design to provide a clean and safe production environment for coal miners. Our methodology and results are of value the formulation and development of effective dust control and clean production technologies.

Research on the dust-control technology of a double-wall attached-ring air curtain on an excavation face.

On the basis of the jet theory of airflow fields and the gas-solid two-phase flow theory, we studied the law of dust migration in a simulated dusting space. We used the control variable method and numerical simulation software to explore the airflow field and dust concentration distribution on the working surface of the dusting under different inlet wind speeds and different attached blades of the double-walled annular air curtain. We determined the speed of the inlet of the annular air curtain to be 30 m/s. When the angle of the attached blade was 30°, the dust concentration of the driver and other workers was controlled below 100 mg/m3, which produced the best dust control effect is the best. Using real data, we built a similar test platform to test the airflow field and dust concentration. Through data measurement and analysis, we proved that a dust control system with a double-wall attached-ring air curtain formed a circulating airflow field that could shield dust and effectively reduce dust concentration in the simulated space. The dust removal efficiency of total dust and exhaled dust reached 98.5% and 97.5%, respectively. We compared the test data and simulation results and concluded that the double-wall attached-ring air curtain could effectively ensure the safety of mine production and provide a better underground working environment for operators.

Dust emission evaluation of the flexible metal wheel over lunar terrain and fender effect

The lunar rover’s wheels produce substantial dust emission during movement, presenting safety concerns for astronauts and potential equipment wear. Replicating the dust emission behavior in the low-gravity environment on Earth is challenging. This study proposes a numerical approach to analyze the dust emission distribution of an elastic wire mesh wheel over lunar terrain. The analysis considers adhesion and electrostatic forces within a Discrete Element Method (DEM) model of lunar dust. Then a Multi-Flexible Body Dynamics (MFBD) model of a flexible wire mesh wheel was developed. A virtual single-wheel soil bin experiment was conducted to examine dust emission features under various motion conditions and on rough terrain. Additionally, alternative structures of dust fender were designed to effectively suppress dust, and the effects of the structural features on dust emission were further explored. This comprehensive study provides a valuable reference for simulation and dust-control technologies related to elastic lunar wheels, offering insights that contribute to the effective management of dust emissions from lunar rover wheels.

Research on the optimal parameters of wind curtain dust control technology based on multi factor disturbance conditions

For the current coal mining surface air curtain dust control technology to control the low efficiency of the problem of dust, numerical simulations were used to study the effects of three factors on dust control efficiency: air outlet width, air volume, and placement angle, to improve the effectiveness of its application. The results show that the air outlet width and the air volume have a significant effect on dust control efficiency, while the placement angle has less of an effect. As the air outlet width increases from 50 mm to 250 mm, the peak wind speed of the wind curtain gradually decreases and the dust removal efficiency first increases and then decreases. As the air volume increases from 30 m3/min to 150 m3/min, the peak wind speed of the wind curtain increases significantly and the dust control efficiency first increases and then decreases, changing significantly. As the angle of placement increases from 5° to 25°, the wind speed of the wind curtain essentially remains the same, and the dust removal efficiency increases slightly before decreasing. The optimum performance for the wind curtain in controlling dust is achieved when the air outlet width is 150 mm, the placement angle is 10°, and the air volume is 90 m3/min. Field tests show that applying this technology has resulted in a significant reduction in the dust concentration from 857.26 to 68.83 mg/m3 in the working area of the shearer driver, representing a dust control efficiency of 92%. This technology has greatly improved the working conditions in coal mining areas.

Wetting characteristics and kinetic behavior of amphoteric ionic surfactant on the microscopic “solid-liquid” interface of coal - A case study

This study investigates the wetting characteristics and kinetic behavior of amphoteric ionic surfactant on the microscopic “solid-liquid” interface of coal based on low-field NMR experiment combined with molecular dynamics simulations, since the basic research on the wetting mechanism of coal seam water injection is not systematic and in-depth enough, which restricts the further development of dust control technology in mines. Firstly, the wetting characteristics of amphoteric surfactant (CAB-35) on coal with different degrees of metamorphism and the dynamic spreading of the wetting range were obtained by low-field NMR experiment, revealing the microscopic wetting law at the “solid-liquid” interface of coal; In order to establish the numerical simulation operation system of interfacial wetting of coal macromolecular structure characteristics based on coal surface chemical parameters and using molecular dynamics theory, the wetting dynamic behavior of amphoteric ionic surfactants on coal dust is studied from microscopic perspective, and the law of influence of surface chemical characteristics on coal wetting characteristics is obtained, so as to improve and enrich the theoretical system of coal wetting, in order to promote the development and enhancement of coal mine water injection and wetting and dust control technology and clean production, and realize the clean production of mines.

Numerical simulation of dust control technology for longwall working face with convective air curtain.

A convection-type air curtain dust control system and method were proposed to effectively control the high dust concentrations generated during the operation of coal miners and hydraulic supports and to reduce the dust concentration in the entire working space of longwall work surfaces, and the effectiveness of air curtain dust control during single process operation was investigated through numerical simulation. The results showed that when the miner was working alone, there was a significant difference in the concentration distribution inside and outside the dust-proof air curtain, with significantly lower dust concentrations in the area where the miner drivers were operating compared to both sides, with an average dust mass concentration of around 420 mg/m3. Dust concentrations increased to about 700 mg/m3, but large amounts of dust were prevented from diffusing downwind. This indicates that the dust reduction effect is more pronounced after the equipment is opened, which can improve the working environment and reduce the probability of dust combustion and explosion accidents.

Bagasse dust exposure and chronic respiratory symptoms among workers in the Metehara and Wonji sugar factories in Ethiopia: a longitudinal study design

BackgroundEthiopia’s sugar factories are growing by creating job opportunities for thousands of workers with varying educational, professional and socioeconomic backgrounds. These sugar factories are a source of several hazards that...

Discussion on Dust Control Technology of Coal Mine Integrated Excavation Face

Coal is an important energy source in our country, and coal mine dust seriously endangers production safety and occupational health and safety, so it is necessary to take effective technical measures to prevent and control the coal mine. According to the main technical ways of dust prevention and control, the technical measures such as improving dust-proof water, strengthening coal seam water injection, carrying out high-pressure external spray, dust control and dust extraction purification, air flow purification and individual protection are discussed respectively. Finally, the technical measures of dust prevention and control in the future are prospected, and several technologies and equipment should be emphasized to break through.

A Study on Dust-Control Technology Used for Large Mining Heights Based on the Optimization Design of a Tracking Spray Nozzle

Intense cutting-induced dust production in fully mechanized mining faces (FMMFs) with large mining heights produces a high amount of dust that is difficult to capture and severely affects the working environment, threatening the health of occupational staff. The effective spray range and atomization performance of tracking sprays are counteracted by the influences of the mine’s height and ventilation airflow in FMMFs. Thus, optimizing the spray’s parameters and relationship between the effective spray range and atomization performance to reduce dust levels is the main priority of dust-control techniques. In this study, a new swirl-core atomization nozzle is developed based on fluid mechanics and the solid–liquid coalescence mechanism. The liquid generates a circumferential velocity when passing through the swirl core, which considerably increases the droplet breaking power and reduces the droplet cohesion factor, achieving a remarkable atomization effect. The spray angle of the new nozzle is 57°, which is 80.9% greater than the GZPW-16 mine-use nozzle (31.5°); the effective spray range increases from 5.2 to 5.9 m; and the spray’s mist saturation is significantly better than the GZPW-16 mine-use nozzle. Under different test pressures, the particle size range of the droplets produced by the new nozzle and dust particles on site satisfied the best synergy of droplet–dust coalescence. The total and respirable dust-reduction rates were 78% and 75.1%, respectively, which were 42% and 65% higher than those of the original nozzle. The new nozzle effectively improves the efficiency of the single dust-control technique of the tracking spray, which is significant for the dust-prevention and -control technology of FMMFs with large mining heights.

A novel method for reducing the amount of dust produced by roadheaders based on the numerical simulation of coal breakage

Dust pollution is a serious environmental hazard during the tunneling in coal mines. Despite the presented dust control technologies, the method of reducing dust production has not been adequately investigated. This paper conducted cutting tests with various tip angles and attack angles using numerical models. A novel method for reducing the production of dust, based on the simulation results, was proposed and verified in the field experiments. The cutting force, work and crack extensions were analyzed. The concentrations of dust in laboratory tests were linked to the simulation results. The simulated results showed that the conical pick with a large tip angle could increase the cutting force and work and cause more cracks. The attack angle had a negative relation with the cutting force and work. The field experiments suggested that the amount of dust could be significantly reduced by using conical picks with a small tip angle. A slower rotation speed of the cutting head could alleviate dust hazards. The results are of momentous relevance for mine managers and researchers to reduce the production of dust during tunneling and control the dust more efficient.

Research on airborne air curtain dust control technology and air volume optimization

The mechanization ratio of coal mining faces has reached more than 90%. However, the coal dust pollution in the fully mechanized mining operation is still an urgent problem to be solved, especially in the working area of the shearer driver. Therefore, an airborne air curtain dust control technology is proposed. The air current migration and dust pollution diffusion in a working face under various air volumes were studied using CFD numerical simulation technology. It was found that two high-speed air curtains form at the shearer driver’s operating position, while a trapezoidal full-section clean air chamber formed at the sidewalk, which could effectively block the dust engendered by the coal cutting drum. The air curtain with 90 m3/min air volume has the best dust control effect in this area, and the diffusion distance of high concentration dust is reduced by 90 m. After applying this technology in the field, the dust concentration in the shearer driver’s working area was reduced to 79.23 mg/m3, and the dust control efficiency was 83%. It is proved that the technology can reduce the dust concentration in the whole tunnel, especially at the shearer driver operating point. This work provides valuable information for dust prevention and control in a working face.

Field experimental study on comprehensive dust control technology in fully mechanized caving face of extra thick coal seam

In order to solve the dust treatment problem of the coal Permian extra thick coal seam mined by Tashan Coal Mine, the comprehensive dust treatment technology research was carried out with the 8106 comprehensive discharge face and 8210 comprehensive discharge face of Tashan Coal Mine as the geological background, and the four aspects of coal seam water injection process, determination of water injection parameters, inspection of water injection and dust reduction effect and application promotion prospects were analyzed and studied.

Study on dust control technology of mobile spray combined with full-section fog curtain in return airway of header working face.

For the problem of coal dust pollution in the return air lane of the comprehensive mining working face of soft rock mines.Based on the principle of supersonic siphon pneumatic atomization dust control, mobile vehicle-mounted pneumatic spraying combined with full-section fog curtain dust control technology is proposed to address the coal dust pollution problem in the return air tunnel of the comprehensive mining working face of soft rock mines. This technology has a wider spraying range, stronger wind resistance and lower energy consumption.Using the k-ε turbulence module and the fluid flow particle tracking module of COMSOL simulation software, a three-dimensional numerical model of the return air tunnel was established. The effect of wind flow characteristics on the diffusion range of coal dust and fog droplets was analysed, and the dust transport pattern and dust control effect of the new technology were obtained for different cross-sectional return airways. The results show that the velocity of the wind flow is continuously decayed by the slope, and the dust of different particle sizes is distributed differently by the inertial force. Coal dust with particle sizes larger than 6.5 μm accumulates below the structure at a lower velocity, and coal dust with particle sizes smaller than 4.5 μm is mostly suspended above the structure at a higher velocity. The device effectively stops the transport of dust and covers the whole section of the roadway, and the dust removal efficiency reaches 96.53%~97.93%, which provides relevant theoretical support and treatment means for the control of dust pollution in the return airway of coal mines.

Research on dust dispersion law of fully mechanized mining faces under different inclinations and tracking closed dust control method

Based on the gas–solid two-phase flow theory, numerical simulation of the dust dispersion law of fully mechanized mining work under different inclination angles and comparative analysis of field-measured data show that with the increase of working face inclination, the inclination of airflow into the unmined zone increases from 25° to 50° and the maximum wind speed increases from 2.16 to 2.25 m/s after the mixing of cutting turbulent wind and system ventilation. Meanwhile, the range of high-concentration dust clusters, suspension time, lateral migration intensity, and deposition zone increase to varying degrees; dust clusters increases from 62.02 to 202.46 m3. When X < 53.96 m, the dust concentration in the sidewalk-breathing zone shows a sine function with the length of the working face, and when X ≥ 53.96 m, it satisfies the exponential decay function. Based on this, the tracking closed dust control technology is proposed. Combining the offset angle of the airflow and t the gathering position of dust mass, the wind curtain angle and air velocity are automatically controlled to ensure that the dust is restricted to one side of the cable trough.