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Water infusion using gas drilling in return airway (Fu and Chen 2003)

Water infusion using gas drilling in return airway (Fu and Chen 2003)

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Coal mine dust continues to be a health and safety issue in underground coal mines. Coal seam water infusion was developed and widely applied in European coal mines for dust control, and was also a common practice in most Chinese coal mines. This method typically involves the infusion of water into the coal seam to increase its moisture content, an...

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... In this study, we explored the dynamics of coal dust movement in a fully mechanized mining face in the presence of airflow. To accurately simulate the behavior of dust particles, we employed a discrete phase model (DPM) for the two-phase coupling simulation calculation (Shi et al. 2022;Zhang et al. 2019;Liu et al. 2022a;Xiao et al. 2022). The DPM allowed us to treat the airflow as a continuous phase while considering the dust particles as a discrete phase. ...
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To control the diffusion of high concentrations of coal dust during tunnel boring and minimize the threat to the life and health of coal miners, theoretical analysis, numerical simulations, and field measurements were combined in this study. First, computational fluid dynamic simulation software was used to simulate the generation of dust particles and their transport pattern in the tunnel. Subsequently, an innovative orthogonal test was performed to study the effect of four ventilation parameters [the pressure airflow rate (Q), distance between the air duct center and heading face (LA), distance between the air duct center and tunnel floor (LB), and distance between the air duct center and nearest coal wall (LC)] on dust diffusion. According to the orthogonal test results, the optimal ventilation parameters for effective dust control are as follows: Q = 1400 m³/min, LA = 7 m, LB = 2.8 m, and LC = 1 m. The optimized set of ventilation parameters was applied to the Wangpo 3206 working face. The results show that dust diffusion in the tunnel was effectively controlled and that the air quality was sufficiently improved.
... Coal and gas outburst is a kind of dynamic disaster in the coal mine caused by the rapid release of deformation energy and gas expansion energy of the coal seam. 1 Poor gas extraction is an important factor that induces coal and gas outburst. 2 Coal mines often use coal seam water injection, 3 hydraulic punching, 4 hydraulic cutting, 5 hydraulic fracturing, 6 hydraulic extrusion, 7 and its integration with blasting 8 and many other hydraulic-based measures to improve coal seam permeability and gas extraction efficiency and so as to eliminate the outburst risk. After water invasion, a large number of water molecules inhibit the diffusion and seepage of gas in coal seams and reduce the desorption rate and desorption capacity of gas. ...
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Gassy coal seams generally have low permeability and dry coal bodies, which are susceptible to coal and gas outburst hazards in the process of mining. Water injection into coal seams can significantly alter the gas release rate and flow behavior. However, water has dual effects on coal seams: gas displacement and water-locking, and the coupling mechanism of these two effects is not clear in the whole process of coal seam water injection. By measuring high-pressure gas adsorption isotherms and gas diffusion initial velocity, it was found that both the Langmuir adsorption constant a and gas diffusion initial velocity ΔP decrease with the increase of water content, which would reduce outburst risks. Through the self-developed integrated experimental device of “gas adsorption + water injection displacement + gas desorption″, the changing rules of gas displacement amount, desorption amount, and water lock amount under different water injection conditions were studied. The results show that when the water injection ratio increases from 6 to 25%, the gas displacement would increase from 0.62 to 1.16 mL/g, with an increase of 87.09%. Also, at the same time, the gas desorption capacity would decrease from 4.86 to 4.05 mL/g after pressure relief, with a decrease of 16.67%. The amount of water-locking increased from 0.11 to 0.38 mL/g. The effect of water injection to control coal and gas outburst occurs in two different water injection stages. In the process of water injection, water plays a major role in gas displacement, which is conducive to reducing the gas content of the coal seam. After the completion of water injection, the static water pressure remaining in the coal seam can reduce the gas emission rate. The combination of these two effects can effectively reduce the risk of outbursts.
... In dust control, the method of injecting water into the coal seams is commonly used to enhance the moisture content of coal and achieve dust prevention (K. X. Zhang et al. 2019). The degree of coal metamorphism, chemical composition, oxygen functional groups, and small molecular all influence the wetting properties of coal. ...
... Because a coal seam is affected by the mine's pressure and geological structure, a certain amount of primary mine dust is produced and contained in the fissures of the coal seam and the surrounding rock [24]. In the various links of the coal production chain, such as mining and transportation, secondary mine dust and water are generated by the cutting, crushing, and loading and unloading of coal and rock masses [25]. ...
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When it comes to grouting in coal mines, polyurethane (PU) is often utilized. However, it is of vital importance to consistently improve the mineral PU, considering the significant amount of environmental deterioration to which it is prone. Laboratory experiments were used to model various coal mine conditions. Additionally, a workable technique for PU strengthening using ultrasonic waves was proposed. Compression tests and scanning electron microscopy (SEM) were used to describe the PU–gangue material’s induration characteristics. The results showed that ultrasound has a positive impact on PU’s mechanical strength. The final strength of the PU was significantly impacted by the size of the coal gangue particles, the amount of dust, and the amount of water. The induration made of gangue and PU with the same mass but differing particle sizes was noticeably different in its compressive strength. The strengthening mechanism showed that the average size of the rigid foam after the ultrasound treatment was smaller, and the ‘honeycomb’-structured space in the inner section was more compact, resulting in the rigid PU foam having a higher compressive strength after ultrasound treatment. Furthermore, the dust content and water content of coal mines need to be controlled within a specific range to ensure the effective use of PU grouting materials.
... Rao et al. simulated airflow and dust migration during operations in tunnels (Xie et al. 2018). In addition, Fang et al. studied the effect of the distance between the air duct outlet and the working face on the airflow and dust during the construction of a highway tunnel (Zhuo et al. 2021;Zhang et al. 2019). Using CFD software, Toraño et al. studied the change in the air speed and dust concentration in each section of a tunnel with pressin ventilation (the main ventilator pressed fresh air into the area of the working face) and far-pressing-near-absorption (FPNA) ventilation (Toraño et al. 2011). ...
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... 9 Zhang found that predrilled gas drainage boreholes as subsequent water infusion holes have an advantage in reducing operational cost but needs more research. 10 Cheng proposes that efficient fluctuation water injection technology with permeable agent be used at low permeability coal seam and the water injection pressure fluctuates between 7 MPa and 25 MPa. 11 Huang finds the integrity of the sample is found to be far lower than after traditional hydraulic fracturing, by following hydraulic fracturing that has been conducted after water pressure blasting. ...
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Rock burst disasters can be reduced and prevented with the help of coal dust water injection. In this study, the high‐pressure water injection device is used to examine how the water absorption rate changes over time under various water injection pressures. The results reveal that the water absorption rate of coal samples increases quickly initially before slowing down with water absorption time. Its change can be described using the Langmuir equation. In addition, the Langmuir equation is utilized to demonstrate how water injection pressure affects the maximum water absorption of coal samples. The effects of experimental findings and numerical analysis are investigated on water injection pressure. The breadth and extent of coal bodies with increased moisture are continuously expanding at the same water injection pressure and water injection time. The water absorption of coal close to the borehole remains relatively unchanged with an increase in water injection pressure, but the water absorption range of coal in the vicinity increases. Therefore, raising the water injection pressure and duration will improve the effective range of water injection. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.
... Longterm exposure of employees to air containing coal dust can lead to coal workers' pneumoconiosis and seriously affect their health (Finkelman and Tian 2018;Fan et al. 2018;Fan and Liu 2021;Shekarian et al. 2021;Zhang et al. 2018). In addition, flying dust will damage mechanical equipment, pollute the surrounding environment, and cause economic losses (Li et al. 2021;Zhang et al. 2019). In coal mines, the most common approaches to control dust are hydraulic methods, such as water spray, and coal seam water injection. ...
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... Coal seam water injection is a widely used dust reduction technology in underground coal mines due to its high efficiency and low cost (Hou et al. 2022;Zhang et al. 2019). As coal seam mining expands in-depth, the permeability of the coal seam gradually decreases, while the strong hydrophobicity of the coal and the high surface tension of pure water both seriously impact the effect of coal seam water injection. ...
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This paper determines the optimal surfactant concentration for enhancing coal’s wettability and explores the wetting mechanism at surfactant concentrations above the critical micelle concentration (CMC) during coal seam water injection. In this study, laboratory experiments and field tests were used to investigate the influence of monomeric surfactants and compound surfactants at various concentrations on coal’s wettability. The results showed that when the surfactant solution concentration was greater than the CMC, the coal’s wettability was significantly enhanced as the surfactant concentration increased. However, the coal’s wettability did not monotonically increase with the concentration, and the maximum value was reached in the range of 0.5–3 wt.%. Increasing the surfactant adsorption density and changing the adsorption state on the coal surface were the essential reasons surfactants continued improving the coal’s wettability at concentrations above the CMC. The Marangoni flow effect and changes in the viscosity of the surfactant solution with concentration were also important factors that affected the coal’s wettability.
... This device can be used to reduce the dust concentration during roadway excavation. Zhang et al. (2019) developed a dry-wet composite dust suppression device in the return duct. Peng et al. (2020) developed a full-face water curtain dust suppression device for roadways. ...
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The application of the cantilever tunneling method in urban metro tunnel constructions has been gradually promoted. High concentration of dust will be produced near the working face when a boom-type roadheader is used to excavate a small and narrow metro tunnel in hard rock. If not controlled in time, high concentration of dust will escape in the working wells, the air in cities will be polluted and the health of residents will be affected. To maintain the sustainable development of cities, a U-shaped dust suppression device with optimized nozzle arrangement installed at the front end of the boom-type roadheader is proposed in this study. Firstly, the atomization characteristics of four different types of nozzles were analyzed by an indoor model test. The optimum nozzle is determined to be a fine solid conical nozzle with a diameter of 1.6 mm. Then, the dust diffusion law in the core dust producing area under the action of an air compressor is analyzed based on the discrete phase model of computational fluid dynamics; the influence of the parameters of the complete spray device on the performance parameters of the droplet field is discussed in detail based on the Taylor analogy breakup simulation method. The results show that when the spray pressure is 8 MPa and the number of nozzles is 11, the formed droplet field has the best encapsulation and the high concentration droplets account for 77.36%. Finally, the device is applied and verified on site. The test results show that the maximum total dust suppression efficiency in the tunnel reaches 81.48%, the maximum respirable dust suppression efficiency reaches 81.51%, and the dust suppression efficiency at other monitoring points is also above 70.41%.
... Coal-seam water infusion is a preventive measure, which can reduce the level of dust generated throughout the entire coal-mining course. Zhang et al. (2019)reviewed water infusion technology and analyzed existing problems and the prospects for the development of water infusion techniques. The dust removal efficiency of this measure can reach 50-80%. ...
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The development of coal industry is restricted by dust pollution. Air curtain dust control technology was proposed as a solution to the serious problem of pollution. A mixture of numerical modeling and field tests has been used to study this technology. Numerical simulation is used to analyze the dust control effect of this technology under different dust generation conditions. Field measurements are used to verify the effectiveness of this technology. The results show that following the application of this technology, the fan-shaped air curtain generated by the fans forms a trapezoidal protective area between the coal cutter and the sidewalk. This protective area prevents dust from entering the coal-cutter driver’s workspace. The average dust concentrations where the coal-cutter driver works were 1590 and 466 mg/m³, severally, before and after the implementation of this technology. The dust control rate in this space is approximately 70.69%. This research provides useful data for dust control technology in fully mechanized mining faces, and will contribute to the stable development of coal fuel.