1. Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
2. School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
3. School of Chemistry and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
4. Yanzhou Coal Mining Company Limited, Zoucheng 273500, Shandong, China