Abstract:With chlorine (Cl2) as oxidant of Fe2+ and Co2+ oxidation and Na2CO3 as precipitant, the depth removal of iron and cobalt, the utilization rate of Cl2 and the composition of iron-cobalt removal residue after copper removal from nickel electrolytic anodic solution by hydrogen sulfide were systematically studied. The optimum process conditions for removing iron and cobalt by Cl2 oxidation precipitation method were established through orthogonal experiment and single factor experiment, and the existing forms of nickel, iron and cobalt in iron and cobalt removing residue were clarified. The results show that the oxidation and precipitation of Fe, Ni and Co by Cl2 are exothermic reactions, which can be spontaneous, and the thermodynamic reaction order is Fe2+ > Co2+ > Ni2+. The results of orthogonal test and single factor test are consistent. The removal rate of Fe2+ and Co2+ is 99.8% and 97% respectively, the utilization rate of Cl2 is 97% above, and the Ni/(Fe+Co) of iron and cobalt slag is 0.88 under the optimum conditions for removal of iron and cobalt including pH value of 5.0 before Cl2 inlet, ORP =1 050 mV at the end point of Cl2 inlet, and pH≥4.5 at the end point of reaction. Fe-Co removal residue is mainly composed of Ni, Fe, Co, O, S and other elements. Ni is dominated by +2 valence, while Fe and Co are dominated by +3 valence.