Studies On The Process Of Removal Copper Using Nickel Sulfide From Mixed Acidic Nickel Electrolyte System

With the development of electroplating,petrochemical industry,precision alloy and other industry technology,the requirements for the quality of electrolysis nickel have been increased year by year.The purity of nickel electrolyte played a key role in the quality of electrolysis nickel during the production process.Since nickel and copper elements exhibited similar chemical properties,the effective separation of these two elements is difficult,which is a long-term problem in metallurgical industry at home and abroad.In order to solve this problem,our country continuously listed it as a focal item in the eighth and ninth "Five-Year Plan" period.Jinchuan Company and many domestic and foreign research institutions have tried various approaches,some commercial scale tests were also carried out.However,the problem has not been effectively solved yet.In recent years,Jinchuan Company has solicited public advice for seeking efficient technology to remove copper.Due to the fact that it has been unresolved for a long time,Jinchuan company had to lower the expectations during the period of eighth" Five-Year Plan".Specifically,the content of the copper for the treated solution was changed from2 mg·L-1 to 3 mg·L-1,the ratio of copper and nickel are also changed from 20 to 15.Based on copper's sulphophile affinity,this study used the nickel sulfide to remove copper.Firstly,sulfite was added to the iron-removed solution and the sulfite would react with copper iron to form the Cu+.Then put sodium sulfide into mixed acid solution of nickel and made the nickel-sulphide slurry liquid.At last,nickel-sulphide was added to iron-removed solution in order to remove copper,which can reduce the concentration of Cu2+ to 2mg·L-1 or less,and the ratio of copper slag and copper-nickel was equal or greater than 15.After carrying out the cobalt in copper-removed solution,the final solution was to meet the production need of electrolytic nickel.The main contents and results of this study were as follows:The thermodynamic equilibrium of Cu-Ni-Cl-Pb-Zn-H2O system for nickel anode electrolyte was calculated according to the principle of simultaneous chemical equilibrium.The results indicated that,in nickel electrolysis solution at the condition of 298.15K,pH 4.5,[Cl]T=2.113mol·L-1,the main occurrence states of copper are Cu2+,CuCl+and CuCl2(aq),while the CuCl3-and CuCl42-concentrations were low;when the total nickel concentration of 1.282 mol·L-1,the nickel mainly existed in Ni2+,NiCl+and NiCl2(aq),forms,where the highest concentration was Ni2+.The reduction of copper ion by sulphite and its removing from the nickel-sulphide slurry liquid were studied by kinetic analysis.It also demonstrated the feasibility of the improvement of the copper removal reaction rate.The effect of solution pH for copper removal was investigated,and the influence of reaction time,reaction temperature on the copper removal was studied,besides,the copper removal active time of nickel-sulphide slurry liquid was also investigated under mixed acid system.The research results showed that under the condition of temperature 70?75?,the nickel-sulphide slurry liquid according to 0.6?0.7 times was added into pH 3.8 iron liquid,60 minutes later,the copper removal depth can reach 3 mg·L-1,the ratio of copper slag and copper-nickel was equal or greater than 15.In 24 h,the nickel sulfide slurrying fluid had good copper removal activity,and met the demand of copper removal.