New Three Sections Of Wet Zinc Smelting Purification Technology Was Studied

The main impurities from the zinc sulfate leaching solution which affect the quality of products are Cu、Cd、Ni、Co、As、Sb、Ge and so on. As to Cu、Cd、As、Sb、 Ge are often removed by the method of zinc replacement in the existing production and the technology is relatively skilled. But Co、Ni is difficult to eliminate, at present, the mainly method to remove Co、Ni in the purification of zinc sulfate leaching solution at home and abroad are zinc replacement and organic reagent. The current widespread use of the zinc-antimony salt method in the purification process which need to maintain high temperature and add excessive zinc powder in order to improve the depth of purification and purification efficiency, this method entails large amount of zinc powder, high production costs, poor working conditions, and the output of the slag contain high zinc while nickel and cobalt are low which is not easy to be processed, besides, it is difficult to utterly remove the impurities such as Co、Ni 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, by using a new type of heavy metal precipitation agent(K-agent) to remove Co、Ni from the zinc sulfate leaching solution, a new purification craft for zinc hydrometallurgy through a large number of laboratory experiments is developed which is carried out half-industrial test containing the whole process of purification and electrowinning and the removal of high Co、Ni from the low-cadmium solution, the effect is good.In this paper, the new three-stage craft of purification is particularly researched. Firstly, to make better the traditional craft which need to remove Cu、Cd and a large proportion of Ni at the same time, engaging in condition experiments such as zinc powder amount, reaction temperature and reaction time. Secondly, engaging in qualification experiments such as the usage of K-agent and the auxiliary precipitating reagent as well as the relationship of use level between K-agent and the auxiliary precipitating reagent in the second process of the new craft to remove Co, then studies relevant condition experiments about K-agent to remove Ni, including the consumption of K-agent and the auxiliary precipitating reagent, the interference of Co and Cd. In a domestic zinc hydrometallurgy factory we have carried out a host of tests of the first stage which removes Cu、Cd、Ni by doing at single slot and continuous purification of zinc powder test, and also the second stage to remove Co、Ni, as well as the whole process of continuous purification and the single big slot electrolytic experiment. To determine the optimum parameters of the new purification craft: the first stage is to remove Cu、Cd、Ni, the addition amount of zinc powder is2g/L, reaction temperature is60～65℃,zinc powder retention time is50-60min, mechanical stirring; the second stage is to remove Co、Ni by K-agent, the addition amount of the K-agent and the auxiliary precipitating reagent is respectively0.2g/L and15mg/L, reaction temperature is85～90℃, reaction time is60-90min, mechanical stirring; The third stage is to remove residual Cd by using zinc powder at low temperature, the addition amount zinc powder is0.2g/L, reaction temperature is40～45℃,reaction time is45-50min, mechanical stirring.Compare with the traditional method of zinc replacement, xanthate reagents and β-naphthol, the new purification craft is characterized by a series of merits such as:high purification depth, especially the content of Co is stable below0.05mg/L, the content of Cu、Cd and Ni is respectively stable below0.3mg/L、1mg/L and0.2mg/L while As and Ge of that are stable below0.05mg/L which is obviously superior to the current widespread use of the zinc-antimony salt method; substantially save zinc powder consumption; the process is relatively simple because of without adjusting pH; the slag contain high Co、Ni while low zinc, which is easily to processed and do not need to secondary process, facilitate to remove and the recovery of Co、Ni from the system; environment friendly in that not produce the stink compare with the xanthate method; suitable for mineral processed which comprise high proportion of Co、Ni etc.