1. College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266590, China
2. Key Laboratory of Ministry of Education for Mine Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, Shandong 266590, China
3. School of Chemical & Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China