The Study Of The Process Of Using The Crude Nickel Hydroxide In The Production Of Nickel Sulfate

Crude nickel hydroxide is one of the main raw material for the production of nickel sulfate and electrodeposited nickel.Now, Ni²⁺ concent in the Crude nickel hydroxide produced by the hydrometallurgical leaching is about 43%-52% and there are cobalt, iron, calcium and other impurities in it,so further purification must be done for preparing qualified production of nickel sulfate and electrodeposited nickel.Regard the crude Ni（OH）₂ prepared by nickel sulfide concentrate in Shaanxi nonferrous metals group company as raw materials,the paper studys the production process of NiSO₄ by experiments.The process routes "acid soluble- extraction- the cooling crystallization" prepared for NiSO₄ and parameters is determined by the experiment.Meanwhile,the technology that electrodeposited nickel prepared with crude Ni（OH）₂ has carried on the preliminary design.The research content is as follows:（1） Crude NiSO₄ solution is prepared by Crude Ni（OH）₂ dissolved in acid,and then extract the impurity.Based on the experiment of extracting and separating impurity in the NiSO₄ solution,some factors that affect the extraction rate is studyed such as extraction concentration,O/A,extraction time and initial solution pH.The optimum process conditions of the impurity removed by P204 extracting was determined:The composition of organic phase is 20% P204+80% sulfonated kerosene, O/A is 1:1, the initial solution pH is 2.2, the temperature is 40℃, the oscillation time is 5mins, the extraction series is 5.Under the optimum conditions, the extraction rate of Fe³⁺ is above 99%, and the extraction rate of Ca²⁺ is above 96%, and the loss rate of Ni²⁺ can be controlled in 3%.（2） Extract and separate nickel and cobalt by P507,the better technology conditions is determined as this : O/A is 1:1, the solution initial pH is 4.5, the temperature is 30℃, the oscillation time is 5min, and the extraction series is 6.Under the optimal conditions, the Co²⁺ extraction rate is over 92% and the loss rate of Ni²⁺ is less than 3%.（3） On the basis of crystallization thermodynamics analysis, the experiment of cooling crystallization of nickel sulfate was done.The results showed that the solubility of six hydrated nickel sulfate decreased when the initial solution pH decreased.Through the analysis of XRD and thermogravimetric,it is determined that the product prepared by NiSO₄ is NiSO₄·6H2O, the purity of wihch is more than 99%, the product quality in line with industry standards.（4） The metallurgical calculation was done for NiSO₄ prepared with crude Ni（OH）₂,1.2t nickel sulfate can be prepared by 1t crude nickel hydroxide,The recovery rate of main metal ions : Ni²⁺≥94%;Ca²⁺≥92%;Co²⁺≥79%;Fe²⁺≥15%( Using hydrochloric acid as stripping agent, the recovery rate of Fe²⁺ can reach about 90%.).（5） Based on literature review and the enterprise product requirements of the construction of the project, the technology that electrodeposited nickel prepared with crude Ni（OH）₂ has carried on the preliminary design.（6） Using the crude nickel hydroxide as the raw material to produce nickel sulfate is flexible and actual.The production of crystalline nickel sulfate or electrodeposited nickel could be produced according to the change of the market.The enrichment of cobalt, calcium and other slags generated in the process of production can be saled as raw material.