Leaching kinetics of cobalt from roasting-dissolving residue of spent catalyst with sulfuric acid

The leaching kinetics of cobalt from roasting-dissolving residue (Ni-Co concentrate) of a spent catalyst was investigated. The results indicate that the extraction of cobalt from Ni-Co concentrate with sulfuric acid leaching is determined by particle size, sulfuric acid concentration and reaction temperature, while stirring speed in the range of 4001200 r/min shows a negligible effect on extraction of cobalt. A cobalt recovery of 94.2% and a nickel recovery of 93.5% are achieved by leaching 0.0740.100 mm Ni-Co concentrate particles with sulfuric acid of 6 mol/L at 80 ℃ for 180 min. The solid/liquid ratio is kept constant at 1:10, and stirring speed is 800 r/min. The leaching kinetics shows that the rate of cobalt leaching process is controlled by diffusion through the product layer during the overall reaction. The activation energy is about 16.34 kJ/mol. The reaction is controlled by a diffusion controlled process.