Study On Decoppering From Nickel Electrolyte Solution With Amorphous Metal Sulfide

Cu removal from nickel electrolyte has always been an intriguing task in hydrometallurgy. Recently, Cu removal from nickel electrolyte by sulfidation pecipitation method has made great breakthrough. However, those existng Cu removal agents have obvious disadvantages, such as low reaction activities, complex synthetic process, high cost in raw materials and environmental unfriendly, which limited their application in industry. Because of the similar chemical properties between Cu and Ni, current Cu removal process faces the difficulty to guarantee the Cu removal depth, while obtain qualified Cu removal precipitates for Cu matte smelting at the same time.On this basis, we propose amorphous metal sulfides were used as high efficient Cu removal agent to study the deep separation of nickel and coper and the copper removal efficiency. The specific contents are as follows:(1) MnS and FeS were synthesized repectively with Na2S and MnSO4, FeSO4. After the characterization, the results showed both MnS and FeS newly synthesized were amorphous and the average particle size of both metal sulfides is about15-20microns.(2) The effect of Cu removal by amorphous MnS was studied by considering the effect of each experiment condition on Cu removal technology.The experiments results show that the depth of copper removal and mass ratio of Cu/Ni in copper removal precipitate meets the requirement of industry by using amorphous MnS as decoppering agent. Under the reaction conditions:1.6～1.8times the theoretical amount of amorphous MnS, reacting temperature60～80℃, pH value3.5-4.5and reaction time of more than45min, Cu concentration of the solution reduced to less than3mg·L－1and the Cu/Ni mass ratio exceeded15. The enlarged scale experiment confirmed that MnS can be used as a high efficient copper removal agent for larger scale industrial production.(3) The effect of Cu removal by amorphous FeS was studied by analyzing the effect of each experiment condition on Cu removal technology. Results showed that FeS has extremely high efficiency in Cu removal and Cu removal depth requirement can be achieved within2min. Under the optimal reaction condition:1.15～1.25times the theoretical amount of amorphous MnS, reacting temperature25℃, pH value2.5～3.5and reaction time of15min, the Cu concentration in the nickel electrolyte was less than2mg·L－1and the Cu/Ni mass ratio exceeded40, which meet the standard of industry. The enlarger scale experiment was also carried out on FeS as Cu removal agent, and the outcome demonstrated the possibility for applying in industry production.(4) Mn removal by Cl2was investigated, which happened after the copper removal with MnS. After the reaction with Cl2for2.5h, the Mn2+was precipitated prior to Co2+ in the solution. In the subsequent process of nickel electrolysis anolyte purification, removal of Co with Cl2is the last process. Therefore the process of Mn removal totally adapted to the existing purification process.(5)The removal precipitate of which has a mass ratio of Cu/Ni<15had been disposed by CuSO4. The mass ratio of Cu/Ni had been greatly improved, and the precipitate can be used as copper concerntrate for matte smelting. The precipitates which had been aging for30days with mass ratio of Cu/Ni less than15was disposed by0.5mol·L-1CuSO4solution. Under the optimal conditions:reaction time60min, reaction temperature60℃, liquid-solid ratio25:1, pH1.5, the mass ratio of Cu/Ni can be eleated to147.16.In conclusion, MnS and FeS could be used as economical and efficient Cu removal agents and has a good application prospects in nickel metallurgy.