1. School of Metallurgy and Environment, Central South University, Changsha 410083, China; Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China
3. School of Metallurgy and Environment, Central South University, Changsha 410083, China e-mail:
4. School of Metallurgy and Environment, Central South University, Changsha 410083, China; Citic Dameng Mining Industries Limited, Nanning 530028, China