Cobalt recovery and microspherical cobalt tetroxide preparation from ammonia leaching solution of spent lithium-ion batteries

A process for recovering Co and preparing microspherical Co_(3)O_(4)through NH_(3)distillation and phase transformation from ammoniacal solution was investigated.As the basis of thermodynamics,the solubility of Co at different NH_(3)and CO_(3)^(2-)concentrations was studied,and then the effects of different NH_(3)distillation conditions on Co recovery rate were discussed.Over 94%Co and 96%NH_(3)were recovered through NH_(3)distillation,and the cobalt was precipitated in form of cobalt carbonate ammonium compound salt.Through the analysis of the formation mechanism of the precursor,the precipitation process of cobalt could be divided into two stages,and the cobalt precipitation rate was significantly accelerated in the second stage.In phase transformation,the effect of temperature on the roasted product was investigated.The microspherical Co_(3)O_(4)with a microporous structure was prepared at 300°C,and Co_(3)O_(4)with a mesoporous structure and high-spin state was obtained at 750°C.