1. Baotou Teachers’ College, Baotou 014030, P. R. China
2. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China
3. Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China