1. State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of Technology Lanzhou 730050 P. R. China
2. School of Materials Science and Engineering Lanzhou University of Technology Lanzhou 730050 P. R. China
3. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources Qinghai Institute of Salt Lake Chinese Academy of Sciences Xining 810008 China
4. Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province Xining 810008 China