A variety of dust control methods are often applied in coal mines, among which the application of wet scrubbers has proven to be an efficient technology for the removal of dust in airstreams, rather than diluting or confining the dust. In this paper, a wet scrubber design was developed. Based on a self-designed experimental test platform, the total dust concentration, respirable dust concentration, air volume, and average pressure drops of wet scrubbers with 12, 16, 20, and 24 blades were measured under different water intake conditions. The results show that the different water intake levels have only minimal effects on the air volume of the wet scrubbers. However, increased water intake had improved the dust removal efficiency of the wet scrubbers with the same number of blades. The wet scrubber with 16 blades was found to have the best dust removal efficiency at a water intake level of 1.35 m³/h. Its total dust and respirable dust removal efficiency reached 96.81% and 95.59%, respectively. The air volume was 200.4 m³/min, and the average pressure drop was determined to be 169.4 Pa. In addition, when the wet scrubber with 16 blades was applied in a coal preparation plant in China’s Shanxi Province, it was observed that the total dust concentration had fallen below 8.1 mg/m³, and the respirable dust concentration had fallen below 5.9 mg/m³. Therefore, the results obtained in this research investigation provide important references for the use of wet scrubbers to improve coal production environmental conditions.

It is known that high dust concentrations are severely hazardous to health of miners and the safe operations of coal mines. The results of the suppressions of coal dust via chemical dust suppressant methods have been of critical significance, and these methods have been widely applied in coal mines. In this research study, a type of complex dust suppressant composed of surfactants, synergists, and cellulose was prepared. The prepared suppressant was characterized by a high wetting ability and adhesive capacity. The results of the performance tests of this study’s proposed complex dust suppressant showed that its dust sedimentation time was only four seconds, which was observed to be much shorter than that of water alone. Also, the proposed suppressant displayed a viscosity which was 25 times that of water. In this study’s field tests, the proposed complex dust suppressant was used for dust control in a mining roadway of the Zhangcun Coal Mine. The field test results revealed that the average suppression efficiencies of the total dust and respirable dust had reached 89.2% and 87.7%, respectively. Furthermore, a 44.5% increase in the control of the total dust had been observed, and a 65.6% increase in the control of the respirable dust had been achieved with the proposed method, when compared with the results of the previously used water curtain technology.

Considerable methane resources exist in abandoned coal mines. However, methane extraction from abandoned mines in China is still in the exploratory stage. This study presents technologies and engineering practices suitable for the extraction of gob methane from abandoned mines using surface vertical wells, including methane drainage systems, well bottom locations, and an intermittent drainage method. Seven surface wells in the Yongan abandoned mine in China were selected for gob methane extraction. Field results showed that the methane volumetric flow rate of a well whose bottom was close to the gob bottom was 2.5 times greater than that of a well with a bottom located in the gob fractured zone. Moreover, intermittent extraction can enable a well to extract methane cyclically at a high volumetric flow rate. A well drilled mistakenly into a coal pillar can be reused through hydraulic fracturing. The overall maximum methane volumetric flow rate, average concentration, and extraction span were 210 m³/h, 83%, and 1100 days, respectively.

Large amounts of dust particles pose serious hazards to the health and safety of China’s coal miners during roadway blasting processes. It is known that among these dust particles, Particulate Matter 2.5 (PM_2.5) does the greatest amount of harm. In order to study the distributions of the PM_2.5 in roadway blasting processes, a mathematical model of the gas-solid two-phase flow was established in this study, which was based on a Direct Simulation Monte Carlo Method (DSMC). Then, a multiphase flow program was developed. This study’s results indicated that following the blasting processes, fine dust particles gradually floated up and were suspended for long durations in the underground roadway space. The medium-sized dust particles slowly sink to the ground and were eventually expelled before settling to the floor of the roadway. The coarse particles were rapidly settled to the roadway floor. It was determined that the PM_2.5 particles in the front end of the dust group could not be quickly diluted, and the concentrations were high until it is expelled from the roadway, whereas the PM_2.5 dust particles in the back end of the underground roadway were found to be gradually diluted. Eventually, the PM_2.5 concentrations exhibited an alternating thin to dense phase distribution. When compared with the Particulate Matter 5 (PM₅), it was found that the PM_2.5 was more difficult to discharge, and easily formed serious PM_2.5 dust air pollution. This study’s results were determined to be conductive to the future control of PM_2.5 in the underground roadway blasting processes.