1. State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology, Taiyuan, Shanxi, China
2. College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan, P.R. China
3. Key Laboratory of Coal Science and Technology, Ministry of Education, Taiyuan University of Technology, Taiyuan, China
4. College of Mining Engineering, Taiyuan University of Technology, Taiyuan, P.R. China