Preparation of cobalt oxide from concentrated cathode material of spent lithium ion batteries by hydrometallurgical method

Cobalt oxide was prepared from spent lithium ion batteries (LIBs) by reductive leaching, copper sulfide precipitation, cobalt oxalate precipitation and thermal decomposition. The cobalt rich non-magnetic −16 mesh fraction obtained from spent LIBs by mechanical separation was leached using 2 M H2SO4, 6 vol% H2O2, reaction temperature 60 °C, agitation speed 300 rpm, pulp density 100 g/L, reaction time 1 h. The leaching efficiency of cobalt was more than 99% and its concentration was 27.4 g/L. Copper was removed (99.9%) as CuS by precipitating with Na2S. The crystalline solid CoC2O4·2H2O selectively precipitated by treating the copper-free liquor with oxalic acid was calcined to produce crystalline Co3O4, of which primary average particle size was 340 nm.