1. Experimental study on evolution law for particle breakage during coal and gas outburst
- Author
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Wen Nie, Qiao Yan, Peng Yawen, Xin Wu, Jiang Xu, and Tingting Zhang
- Subjects
Materials science ,business.industry ,Underground mining (hard rock) ,Energy Engineering and Power Technology ,02 engineering and technology ,Mechanics ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,complex mixtures ,01 natural sciences ,Stress (mechanics) ,020401 chemical engineering ,Breakage ,Particle ,Coal ,Particle size ,0204 chemical engineering ,Hydraulic machinery ,business ,0105 earth and related environmental sciences - Abstract
Coal and gas outburst is a dynamic phenomenon in underground mining engineering that is often accompanied by the throwing and breakage of large amounts of coal. To study the crushing effect and its evolution during outbursts, coal samples with different initial particle sizes were evaluated using a coal and gas outburst testing device. Three basic particle sizes, 5–10 mesh, 10–40 mesh, and 40–80 mesh, as well as some mixed particle size coal samples were used in tests. The coal particles were pre-compacted at a pressure of 4 MPa before the tests. The vertical ground stress (4 MPa) and the horizontal ground stress (2.4 MPa) were initially simulated by the hydraulic system and maintained throughout. During the tests, the samples were first placed in a vacuum for 3 h, and the coal was filled with gas (CH4) for an adsorption time of approximately 5 h. Finally, the gas valve was shut off and the coal and gas outburst was induced by quickly opening the outburst hole. The coal particles that were thrown out by the outburst test device were collected and screened based on the particle size. The results show the following. (1) Smaller particle sizes have a worse crushing effect than larger sizes. Furthermore, the well-graded coal particles are weakly broken during the outburst process. (2) As the number of repeated tests increases, the relative breakage index grows; however, the increment of growth decreases after each test, showing that further fragmentation becomes increasingly difficult.
- Published
- 2019