Experimental study on particle size distribution of impact crushed coal containing gas

Coal and gas outburst is a coal-rock dynamic disaster caused by the combined action of multiple factors, accompanying by the impact crushing on coal particles containing gas. Therefore, the study of coal impact crushing is of great significance to reveal the mechanism of coal and gas outbursts. In this study, a self-designed experimental system was used to investigate the characteristics of the coal particles under impact crushing. The coal samples from Xiaoqing Coal Mine 7# coal seam in Liaoning (XQ) and Zouzhuang Coal Mine 32# coal seam in Anhui (ZZ) were selected, and tested for drop hammer experiments under different gas pressures. The particle size distribution model and parameters such as surface area distribution ratio and average particle size were analyzed. The results show that GGS model and RR model can well fit the particle size distribution of coal samples after impact. The test results of coal samples with different gas pressures show that gas weakens the strength of coal significantly. A specific functional relationship was established between particle size distribution and specific crushing work and Protodyakonov coefficient, which is expected to be applied in coal mining enterprises.