CAO Jiang-Ping1,2, DI Hong-Wei1,2, LIANG Yong-Feng1,2, LIU Shi-Wei1,2
1. College of Chemistry and Chemical Engineering, Ningxia Normal University, Guyuan 756000, China; 2. Engineering and Technology Research Center of Liupanshan Resources, Ningxia Normal University, Guyuan 756000, China