Study On Modification Method Of Medium Temperature Depth In Zinc Sulfate Solution By Wet

The purification of zinc sulfate solution is an important procedure in zinc hydrometallurgy. And the quality of net liquid can not only improve the current efficiency and the quality of the electric zinc, but also is the prerequisite of realizing mechanization and upsizing for zinc hydrometallurgy industry.Compared with foreign advanced production technology, the level of purification in China has still many deficiencies, such as traditional antimony salt method need to keep higher temperature and adding excessive zinc powder in the process of purification. And the purifying residue is not easy to handle, so it is difficult to make way for cobalt, nickel and other impurities in the system. In view of the actual production status, access to a large number of relevant literature and based on using K agent to solve the problem about cobalt and nickel, a new purifying method of zinc sulfate solution for zinc hydrometallurgy has raised.Firstly, we established the analysis system for detection of impurity elements. And on this basis, we carried out test to remove thallium in pure zinc sulfate solution. The results showed that the thallium content of solution can be removed from4mg/L to below0.1mg/L at lower temperature and add adequate zinc powder. Elevated temperature and excessive longer reaction time will against the remove of thallium.Secondly, in view of cobalt which is the most, difficult to remove in the process of purification, we carried out test to remove cobalt in pure zinc sulfate solution. The results showed that increase the consumption of zinc powder and raise the temperature can be significantly improved removal efficiency of cobalt, at the same time to join a certain amount of Cu2+can not only improve the rate of removing cobalt but also use less zinc powder to reach deep purification. But elevated temperature will against the remove of cobalt.The optimal conditions of the test as follows:adding dosage of Cu2+20mg/L, zinc powder dosage of2g/L, temperature85℃, reaction time60min. Then, in view of the zinc sulfate leaching solution which cobalt content is4.5mg/L, we developed a new purification method. The control conditions of the method as follows:at first stage, the addition amount of zinc powder is3g/L, antimony salt dosage is3mg/L, temperature60℃, reaction time60min; at second stage, the addition amount of zinc powder is0.5g/L, temperature45℃, reaction time30min. Consider the synthetic effect of removing impurity, the first period of purification does good and it does not need too high temperature which control at around60℃is more appropriate. After this process the impurity such as copper, cadmium, cobalt, nickel and thallium has all reached the purification depth requirements. The second period of purification is mainly to prevent the cadmium back dissolve and further improve depth of purification. Finally, in view of the zinc sulfate leaching solution which cobalt content is25mg/L, we improved the original new purification method. The control conditions of the method as follows:at first stage, the addition amount of zinc powder is3g/L, temperature60℃, antimony salt dosage is3mg/L, reaction time60min; at second stage, adding dosage of Cu2+20mg/L, zinc powder dosage of2g/L, temperature85℃, reaction time60min; at third stage, temperature45℃,the addition amount of zinc powder is0.5g/L, reaction time30min.Compared with the traditional antimony salt purification method, we found the new method of zinc sulfate leaching liquid purification has more advantages such as a short and simple process, saving consumption of zinc powder, more depth for purification.