Experimental study of the impact of gas adsorption on coal and gas outburst dynamic effects

Coal and gas outburst is one of major dynamic disasters that have affected safety production in coal mines for many years, in which gas is an important factor that influence its intensity. To analyze the role of gas, especially the role of gas adsorption, in the dynamics of coal and gas outbursts, a self-developed experimental device for the measurement of the dynamic effects of coal and gas outburst was used to perform outburst experiments under different adsorption gas conditions. The device has a simulated roadway sub-system with a length of up to 50 m, which can collect and monitor the typical dynamic effect appearance characteristics such as the shock wave propagation and the pulverized coal distribution of the outburst. Based on the energy theory, we quantitatively discuss the effect of gas adsorption on the outburst. After the outburst occurred, the air in the roadway around the outburst port was disturbed by the shock wave, and the gas pressure rose and then fell within a very short period of time. The adsorption properties of the coal determined the intensity of coal and gas outbursts. The amount of outburst pulverized coal in the CO2 test condition was 3 times larger than that in the air test condition. Additionally, the particle size distribution of the coal samples did not change markedly during the test, indicating that the impact of the crushing effect on the pulverized coal was not significant during the outburst process under the action of gas only. The coal-gas transport energy was 3-5 orders of magnitude greater than the coal crushing energy and the remaining kinetic energy of the gas. It was verified that the role of gas in the outburst process principally related to throwing and carrying the broken coal in the roadway. The energy involved in the outburst process for the CO2 condition was approximately 5.8 times larger than the energy involved in the outburst process for the air condition, which was mainly due to the different adsorbed gas internal energies. The adsorption characteristic is one of key factors affecting the outburst energy and strength. These research results can provide guidance for perfecting coal and gas outburst mechanisms and developing outburst disaster early warning technologies. (C) 2019 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.