1. School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
2. State Key Laboratory of Bayan Obo Rare Earth Resource Researches and Comprehensive Utilization, Baotou Research Institute of Rare Earths, Baotou 014030, China
3. State Key Laboratory of High-Efficient Mining and Safety of Metal Mines of Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China