State Key Laboratory Cultivation Base for Gas Geology and Gas Control Henan Polytechnic University Jiaozuo 454000 China;
State Collaborative Innovation Center of Coal Work Safety and Clean-efficiency Utilization Jiaozuo 454000 China;
Safety Technology Training Institute Henan Polytechnic University Jiaozuo 454000 China;
Huajin Coking Coal Co. Ltd. Lüliang 033000 China;