Study On Ultrasonic Strengthening Of Zinc Powder For Deep Purification Of Zinc Sulfate Solution

With the application of large plate electrowinning technology,higher requirements for electrowinning liquid are put forward.The increasingly prominent significance is possessed by the purification process in hydrometallurgical zinc smelting.Zinc powder replacement purification method is currently the most commonly used method for purification procedures in the industry.In actual production,this method mainly faces the problem of zinc powder agglomeration and wrapping,which caused phenomena such as slow purification speed,high zinc powder unit consumption,and high cost.These requirements for electrowinning liquid have important research significance,which are to solve the problems faced by the zinc powder replacement purification method in actual production and achieve the electrowinning technology.This paper takes zinc sulfate solution as the research object,which taken from the zinc smelting system of a lead-zinc smelting enterprise in Yunnan after leaching.The unique thermal,mechanical and cavitation effects of ultrasound are used.Ultrasonic enhanced zinc powder deep purification process of zinc sulfate solution is proposed.The process parameters and purification mechanism of zinc powder purification of zinc sulfate solution under conventional and ultrasonic enhanced conditions have been explored.The detailed research content is as follows.1)In order to explore the effect of ultrasound on the purification of cadmium and cobalt by zinc powder,electrochemical experiments under different conditions were carried out in simulated solutions.The deposition cyclic voltammetry curves of cadmium and cobalt under different conditions are obtained.The deposition cyclic voltammetry curves under conventional and ultrasonic conditions were compared and analyzed.The enhanced mass transfer of ultrasound was evidenced by the fluctuation of the cyclic voltammetry curve under ultrasound conditions.Therefore it was advantageous to introduce it into the purification process.2)For the zinc powder purification process of zinc sulfate solution under conventional and ultrasonic enhanced conditions,single factor experiments with different factors such as the amount of zinc powder,reaction temperature,reaction time,and ultrasonic power were carried out systematically.The influence of different factors on the effect of removing cadmium and cobalt has been proved.The optimized process conditions for zinc powder purification under conventional and ultrasonic enhanced conditions were obtained.The two purification processes were compared and studied,and it was found that the amount of zinc powder used in the ultrasonic-enhanced zinc powder purification of zinc sulfate solution decreased by 23%,the reaction time was shortened by 69%,the reaction temperature was lowered by 15?,the amount of slag was reduced by 2.73g/L,and the zinc content of the slag was reduced.6.45%,the content of Cd in the purification liquid decreased by 73.9%,and the content of Co in the purification liquid decreased by 73.7%.Ultrasonic enhanced zinc powder purification achieved a deeper purification effect than conventional zinc powder purification.3)The element content,phase composition,microstructure and element valence state of the purification slag were characterized and analyzed by XRF,XRD,SEM and XPS,combined with theoretical analysis,and the purification behavior under conventional and ultrasonic enhanced conditions was proved.The problems of agglomeration,wrapping and resolubilization faced by conventional zinc powder purification are solved by ultrasonic enhancement by enhancing mass transfer,generating lasing jets,and removing dissolved oxygen,thereby reducing zinc powder consumption.4)The kinetic study of the zinc powder purification process under conventional and ultrasonic enhanced conditions was carried out.By adopting the first-order reaction kinetic model,the experimental results of the two processes are fitted.Through calculation,the apparent activation energies of the two processes were compared and studied.Ultrasonic enhanced zinc powder purification of zinc sulfate solution significantly reduces the activation energy of cadmium removal and cobalt removal process compared with conventional zinc powder purification of zinc sulfate solution,the activation energy of cadmium removal process is reduced by 7.41 k J/mol,and the activation energy of cobalt removal process is reduced by 35.18 kJ/ mol.