In this work, previously produced black mass was treated in sequence by milling, water leaching, and sulfuric acid leaching. Two goals were set: first, whether milling, with reductive additives, could impart reductive phase changes which would allow Li extraction to water in the water leaching; second, co-leaching of the black mass with the additive, CoS, was explored as to ascertain whether synergistic effects could be detected in a leaching system composed of reductive (CoS) and oxidative (NMC oxides) materials in the presence of redox mediator (Fe2+/Fe3+ redox pair). It was found out that in all experiments, similar Li concentration was obtained despite milling. Fluoride analysis indicated high F concentrations in the water solution and implicated formation of insoluble products such as LiF(s). Water-soluble fluoride ended up in all fractions: water leaching filtrates (ca. 500 mg/L), acid leaching filtrates (ca. 800-1700 mg/L), and leach residues (ca. 68-382 mg/kg). In acidic leaching, CoS appeared to enhance extraction of elements from cathode-active materials, improving extraction from 78 to 92% for Ni under relatively mild leaching conditions (T = 30 ?, solid conc. = 100 g/L, [H2SO4] = 1.4 M).
展开▼
