1. School of Mines, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
2. China Coal Huajin Group Co., Ltd, Hejin, Shanxi 043300, China
3. School of Environment and Resources, Xiangtan University, Xiangtan, Hunan 411105, China
4. College of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 411105, China