Taiyuan University of Technology, affiliation not provided to SSRN, Taiyuan University of Technology, affiliation not provided to SSRN, affiliation not provided to SSRN, Taiyuan University of Technology, Taiyuan University of Technology, Taiyuan University of Technology - State Key Laboratory of Clean and Efficient Coal Utilization and Taiyuan University of Technology - State Key Laboratory of Clean and Efficient Coal Utilization