Study On New Process Of Cycle Leaching Of Low Grade Zinc Oxide Ores To Produce Cathode Zinc With MACA Method

Aimed at the present situation that the large reserves of low grade zinc oxide ores (Zn<10%) bearing high basic gangues can't be treated effectively, a new process of cycle leaching of low grade zinc oxide ores to produce cathode zinc with MACA method was proposed. Using the low grade zinc oxide ores from Lanping as raw material, a technological process of cycle leaching to enrich the zinc concentration, purification and electrowinning to produce cathode zinc was carried out.Enrichment of zinc concentration, variation of leaching rate and leaching behavior of impurities in the process of cycle leaching was systematically studied during the conditional and integrated experiments of cycle leaching.10 cycle leaching of low grade zinc ores containing zinc 6.59% was carried out under the optimum conditions, the results show that the average zinc concentration of lixivium is 33.93 g/L. The average leaching rate of total zinc and NH3 leachable zinc is 69.08% and 92.34%, respectively. The content of impurities in lixivium is very low."cycle leaching on an enlarged scale-purification-electrowinning" of low grade zinc oxide ores containing zinc 7.72% was carried out based on the optimization experiment. When the cycle leaching is in balance, The average zinc concentration of lixivium is 37.85 g/L. The average leaching rate of total zinc and NH3 leachable zinc is 69.08% and 92.34%, respectively. The content of impurities in lixivium is little. The balance conditions of zinc, total ammonia and chlorine are perfect. The content of total and chlorine is quite low and the loss in washed residue is 0.198 t/t zinc and 0.062 t/t zinc, respectively. The experiment of purification to remove As, Sb and cementation to remove other impurities was carried out. The results show that the content of impurities in purificatory solution is extremely low. The content of As, Mn, Fe, Mg, Si is lower than 5 mg/L and Pb, Cd, Ni, Al, Cu is approximately zero, However, the content of Sb is almost changeless. The electrowinning experiment results show that the average current efficiency is 92.94%. The zinc concentration of spent electrolyte is lower than 17 g/L. The cathode zinc is compact and smooth, containing zinc>99.96% which meets the requirements of second-grade zinc in GB/T 470-2007 standard.The new process of cycle leaching of low grade zinc oxide ores to produce cathode zinc with MACA method can treat low grade zinc oxide ores bearing high basic gangues effectively. This process has lots of advantages, including low energy consumption, a simple flow sheet, easy purification, lower investment, being environment-friendly and so on. Therefore, it is to be significant in solving the shortage of resources and taking a road to new industrialization and sustainable development.