Recovery of valuable metals from spent lithium ion batteries by smelting reduction process based on FeO–SiO 2 –Al 2 O 3 slag system

Abstract A novel smelting reduction process based on FeO–SiO 2 –Al 2 O 3 slag system for spent lithium ion batteries with Al cans was developed, while using copper slag as the only slag former. The feasibility of the process and the mechanism of copper loss in slag were investigated. 98.83% Co, 98.39% Ni and 93.57% Cu were recovered under the optimum conditions of slag former/battery mass ratio of 4.0:1, smelting temperature of 1723 K, and smelting mass ratio of time of 30 min. The FeO–SiO 2 –Al 2 O 3 slag system for the smelting process is appropriate under the conditions of m (FeO): m (SiO 2 )=0.58:1–1.03:1, and 17.19%–21.52% Al 2 O 3 content. The obtained alloy was mainly composed of Fe–Co–Cu–Ni solid solution including small amounts of matte. The obtained slag mainly consisted of fayalite and hercynite. Meanwhile, the mechanism of copper loss is the mechanical entrainment from strip-like fayalite particles in the main form of copper sulfide and metallic copper.