Study On Purification Technology Of New Compound For Cobalt By Zinc Blending In Wet

In zinc hydrometallurgy, the main impurity elements are copper、cadmium、cobalt、 nickel、thallium、arsenic、antimony and germanium.Impurities such as copper、cadmium、 nickel、thallium、arsenic、antimony and germanium can be removed by the method of zinc replacement, but it is need to add rereagents to remove cobalt. At present, the zinc-antimony salt method is widely used in the purification process, but this method has it’s shortcomings such as poor working conditions, zinc powder consumption is far more than amount of theory, high production costs, and the cobalt slag contain high percent of zinc while cobalt percent is low which is not easy to be processed, and it is difficult to utterly remove the impurity cobalt from the system of zinc hydrometallurgy. Owing to all sorts of shortages in the purification process of zinc hydrometallurgy, on the basis of the laboratory research and a large number of laboratory experiments, a new four-stage purification craft which using a new type of heavy metal precipitation reagent(K-reagent) to remove cobalt from the zinc sulfate leaching solution is developed, it is able to achieve the purpose of deep purification.In this paper, the new four-stage craft purification is particularly researched:1) Firstly, in order to make better the traditional craft which can remove copper、 cadmium、thallium and a large proportion of nickel at the same time, a lot of condition experiments such as reaction temperature, zinc powder amount, and reaction time are done in the laboratory; the optimum parameters of the first section:reaction temperature is60～65℃,the addition amount of zinc powder is2.5-3g/L, zinc powder retention time is60～70min. Under the optimum technological conditions, the impurities content in the liquid are:Cu≤0.3mg/L、Cd≤1mg/L、Ni≤0.10mg/L、T1≤0.15mg/L2) Secondly,in the second section of removing cobalt, according to the different cobalt concet in the neutral supernatant, engaging in qualification experiments such as reaction temperature, the usage of K-reagent and the auxiliary precipitating rereagent, and reaction time; the optimum parameters of the second section:if the cobalt content of the neutral supernatant is2-30mg/L, the addition rate of K-reagent is20-110(refer to table3-42), the auxiliary precipitating rereagent is20-25mg/L, reaction temperature is85～90℃, reaction time is60-70min. Under the optimum technological conditions,the cobalt concent is below0.2mg/L.3) If K-reagent remain in the new solution, the quality of electrolytic zinc and current efficiency will be affected adversely, so with an organic matter removal reagent to remove the remaining K-reagent, engaging in experiments such as reaction temperature, the addition amount of the organic matter removal reagent, and reaction time; the optimum parameters:reaction temperature is85～90℃, the organic matter removal reagent is20～25mg/L, reaction time is30-40min. The residual K-rereagent can be eliminated thoroughly in the optimum conditions.4) Finally, according to the traditional methods to remove residual cadmium、copper, engaging in experiments such as reaction temperature, the addition of zinc powder and reaction time; the optimum parameters:reaction temperature is45～50℃, the addition amount zinc powder is0.5g/L, reaction time is30-40min. The impurities content in the new liquid are:Cu≤0.1mg/L、Cd≤0.1mg/L、Co≤0.2mg/L、Ni≤0.1mg/L、T1≤0.10mg/L、Pb≤0.1mg/L、As≤0.05mg/L、Sb≤0.05mg/L、Ge≤0.05mg/L.Compare with the traditional method of xanthate rereagents, β-naphthol and zinc replacement,, the new purification craft is characterized by a series of advantages such as: high purification depth; substantially save zinc powder consumption; the process is relatively simple because of without adjusting pH; the slag contain high cobalt while low zinc, which is easily to processed and do not need to secondary process, facilitate to remove and the recovery of cobalt from the system; suitable for mineral processed which comprise high proportion of cobalt.