Research On Medium-temperature Purification Method Of Hydrometallurgical Zin

The purification of zinc sulfate leaching solution is one of key procedures in zinc hydrometallurgy.And the quality of purified solution not only directly affects electrowinning process,the electrical energy consumption and the quality of the electrical zinc,but also is the basis of achieving mechanization and automation for zinc hydrometallurgy industry.However,the content of impurities increases gradually with the development of zinc ore resources.It is a big challenge to the purification process of zinc hydrometallurgy.The traditional antimony salt method not only needs a higher temperature,but also needs to add excessive zinc powder in the process of purification,thus lead to increase the cost of production greatly.In view of this,the zinc sulfate leaching solution which contains high cobalt was mainly studied in this subject,and the medium temperature purification method was developed.The application of this technology not only reduces the zinc powder and energy consumption,but also makes purified solution reach the advanced purification level.In this paper,the process of purification which in medium temperature was systematically researched:(1)The first period of purification process was improved,hoping to remove almost all of copper、cadmium and make cobalt、nickel reach the deep purification level at the same time.For the cobalt content of 21 mg/L in zinc sulfate leaching solution,a lot of condition experiments such as zinc powder amount,antimony salt dosage,reaction temperature and reaction time were studied in the laboratory,the optimum process conditions were determined:the addition amount of zinc powder is 4.0g/L,antimony salt dosage is 7mg/L,reaction temperature is 65℃,reaction time is 60min.(2)The second period of purification is mainly to remove residual cadmium and further improve depth of purification.A lot of condition experiments such as zinc powder amount,reaction temperature and reaction time were studied in the laboratory,the optimum process conditions were determined:the addition amount of zinc powder is 0.5g/L,reaction temperature is 45℃,reaction time is 30min.(3)As the cobalt content in the zinc sulfate leaching solution is too high and unstable,there may be a risk of not making cobalt to reach the deep purification level,while it is difficult to remove residual cobalt in the second period of purification Therefore,it is necessary to study purified solution whose residual cobalt content is about lmg/L after the first period of purification.(4)Through the study of pure cadmium sulfate solution,a conclusion can be drawn:cadmium can be regarded as catalytic agent in high temperature,return dissolved cadmium consumes zinc powder constantly,thus resulting in a waste of zinc powder.Compared with the traditional antimony salt purification method,the medium temperature purification method studied in this study has more advantages.Based on achieving the same level of purification,medium temperature purification method has a shorter process,better working environment,the consumption of zinc powder and energy is lower.