Study The Impact Of Magnesium On Zinc Electrowinning

China has become a big country of zinc production and consumption. The researches about effect of impurity ion and how to decrease adverse effects in zinc eletrodeposition have a lot and depth-study, with the rapid development of zinc industry. Such as three sections of purification method can be used to remove most of the impurity ions (Cu, Co, Ni, Cd, As, Se). F-1 and Cl-1 formed insoluble material can be removed. K+ and Na+ formed the jarosite slag can be removed while removing ferrous ion. The removal of calcium and magnesium has no economic means, but as the continuous cycle of electrolyte, calcium and magnesium ions are continuously enriched, and some factory had reached 20g/L concentration. It can increase in the viscosity of the electrolyte, reduce the electrical conductivity of electrolyte, thereby reduce the electric current efficiency of zinc and increase in the power consumption, due to the increase in the concentration of magnesium ions. This impact is very big, but this relative research is few.The research aimed at the effect of magnesium ion and how to decrease in adverse effects of zinc eletrodeposition was investigated in this paper, including following four parts.1. Current efficiency, cell voltage and power consumption of zinc electrodeposition were determined by Electrowinning experiments at different magnesium ion concentration and temperature. It is found that at the same temperature, with increasing in the concentration of magnesium ions, current efficiency of zinc deposition is decreased and cell voltage and power consumption are increased. At the same magnesium ions, with increasing in the temperature, the current efficiency reduces and cell voltage is a downward trend, while the power consumption is increased. Finally, magnesium ions is not more than 15g/L at 35℃and lOg/L～15g/L at 40℃and 45℃, otherwise, zinc electrodeposition does not woke successfully.2. Electrolyte basic property such as density, viscosity and electrical conductivity were determined at different temperature and magnesium ions. The results reveal that at the same temperature, with increasing magnesium ion concentration, density and viscosity of electrolyte are increased, while, electrical conductivity of electrolyte reduces. At the same concentration magnesium ions, with increasing the temperature, the greater downward trend of density and viscosity, the higher temperature, while, electrical conductivity is increased.3. The effect of single additive on zinc sulfate containing magnesium ions was researched and better effect additives were selected out. Composite additive was synthesized through better single additive. Composite additive A2 was synthesized and was proved to have a good effect on zinc sulfate containing magnesium ions. The best value of A2 is 15mg/L. Finally, micro-analysis of surface of electrodeposited zinc was carried out with adding A2 and without A2.4. Magnesium ion on the impact of the mechanism of zinc electrodeposition was researched through the polarization curves, Tafel curve, cyclic voltammetry curves, using electrochemical workstation. The results show that electric current density is decreased with increasing in the concentration of magnesium ions. Mechanism of zinc deposition is determined. Magnesium ion on the impact mechanism of zinc electrodeposition is deduced.