1. School of Chemical Engineering and Technology, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China
2. National Engineering Research Center of Coal Preparation and Purification, Xuzhou, Jiangsu 221116, China
3. School of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, Xi'an, Shaanxi 710054, China and Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China