Abstract:Nickel and cobalt were recovered from Ni-Co-bearing purification residues by acid-washing and reduction leaching. The effects of end point pH value during acid leaching and sulfuric acid content, leaching temperature and time, end point pH value, L/S, and hydrogen peroxide concentration during reduction leaching on leaching rate of Ni and Co were discussed. The results show that nickel leaching rate is 78.1% and cobalt leaching rate is very low under the condition of pH value of 2.5 during acid-washing. Nickel leaching rate is 98.3% and cobalt leaching rate is 97.5% during reduction leaching under the optimum conditions including L/S of 10︰1, sulfuric acid concentration of 1.5 mol/L, leaching time of 3 h, leaching temperature of 60 ℃, and dosage of hydrogen peroxide of 1.0 mL/g.