Selective extraction of manganese content from process slag generated from lithium-ion battery black mass.

Pyrometallurgy, a mature processing route, is particularly effective in recovering metals like cobalt, nickel, and copper, from the discarded lithium-ion batteries (LIBs). This process involves high-temperature smelting, which allows for the efficient separation of metals into a metal alloy, although it often results in the loss of lithium and manganese in the slag phase. Our earlier reports discloses a methodology on extraction of lithium (Li) content from LIB black mass in the first step and then subsequently recover the pure cobalt-nickel (Co-Ni) metal alloy in a single smelting step to [R.K.S. Nair, A. Kaushal, A. Barnwal et al., Method for recovery of metals and metal alloys from waste lithium-ion batteries, U.S. Patent. Application No. 18/213 (2024)] (Patent: US-2024-0002978-A1). The process route reported for the formation of binary Co-Ni alloy as metal ingot in smelting whereas Mn content remains in slag. The recovery of manganese from lithium-ion battery slag has significant implications for sustainability and resource efficiency. The current study discloses a methodology for the selective extraction of manganese (Mn) content from the slag produced during the pyrometallurgical processing of black mass derived from discarded LIBs. In this work, the aluminium (Al) and silicon (Si) impurities present in the slag were removed through selective leaching and precipitation process. The optimum parameters for selective precipitation of Al and Mn were systematically studied by varying temperature, time duration, and acid concentration through response surface methodology (RSM). The theoretical thermodynamic predictions were performed through the construction and analysis of Pourbaix diagrams for the optimum conditions of the leaching and precipitation system. The implementation of RSM facilitated the elucidation of the design parameters pertinent to the selective leaching process aimed at the extraction of manganese (Mn) content from the slag generated in LIB processing. [ABSTRACT FROM AUTHOR]