Influence of water content and maceral composition on the properties of outburst-prone coal: laboratory experiment

Abstract

Abstract We conducted laboratory experiments to investigate the influence of water content and maceral composition on the properties of outburst-prone coal using X-ray diffraction and optical electron microscope. For comparison, two groups of experiments were completed on contrasting coals, namely, outburst-prone and outburst-resistant coals. The complete stress–strain behavior, uniaxial compressive strength, Young’s modulus, and acoustic compressional velocity were measured and correlated with water content. Test results showed that the microhardness and microembrittlement of the outburst-prone coal were higher than those of the outburst resistant coal. When the water content increased to 4%, the uniaxial compressive strengths of the outburst prone and outburst resistant coals decreased by 82.4% and 85.1%, respectively; and their elastic moduli decreased by 90.3% and 86.6%, respectively. The difference between the maximum reflectance and the minimum reflectance of vitrinite was smaller for the outburst resistant coal than for the outburst prone coal. The distribution of maceral composition in the outburst resistant coal was simple, and the primary damage was minimal.