Recovery of Valuable Metals from Spent Lithium-Ion Batteries by Smelting Reduction Process Based on MnO–SiO2–Al2O3 Slag System

Abstract

We have previously demonstrated a new pyrometallurgical-based method to recover valuable metals from spent lithium-ion batteries. However, there was no in-depth work on the extraction of valuable metals from polymetallic alloy and manganese-rich slag obtained after smelting reduction. In this paper, two new technologies were investigated, with one combining converting, water atomization, and rusting-leaching of polymetallic alloy, and the other combining concentrated sulfuric acid leaching with roasting of smelter slag. The results show that 98.67% Cu, 99.84% Co, and 99.77% Ni were recovered by leaching the alloy powders in 120 g/L sulfuric acid at 90 °C for 8.0 h, and the solid-to-liquid ratio, agitation speed, and flow rate of oxygen gas are 100 g/L, 1500 rpm, and 0.15 L/min, respectively. Porous alloy powders were produced, which obviously increased the rusting-leaching speed under sulfuric acid media without adding any catalysts. Although only 44.30% of Mn and 50.28% of Li from manganese-rich slag were leached, purer leachate containing Mn and Li can be obtained by the method of co-roasting of manganese-rich slag and concentrated sulfuric acid. This means that the recovery of Mn and Li from the leachate can be directly carried out without any further purification process.