Abstract:The experiments of medium temperature oxygen pressure leaching of Cu, Ni, Fe and S, and synchronous iron precipitation in complex sulfide copper nickel slag were carried out. The main elements in sulfide copper nickel slag were found out, and the effects of oxygen pressure leaching conditions on the leaching rate of Cu, Ni, Fe and S were investigated. The leaching rate of copper, nickel, iron and sulfur is 98.73%, 98.86%, 26.69%, 93.17%, respectively, the residual acid concentration in the leaching solution is 1.28 g/L, and the mass concentration of copper, nickel and iron in the leaching solution is 77.04, 18.80 and 0.67 g/L, respectively, under the optimum conditions including dosage of sulfuric acid (98%) of 20 g (i.e. 200 kg sulfuric acid per ton of copper-nickel slag), leaching temperature of 170 ℃, oxygen partial pressure of 0.4 MPa, liquid-solid ratio of 5 mL/g, and leaching time of 5 h.