Preparation Of Low-grade Zinc Oxide Ore Leaching Process Research And Active Zinc Oxide

With the rapid growth of zinc productivity in recent years, it is becoming more and more significant to make better use of various raw materials as the deposit of zinc resources and the quality of zinc ores are decreasing. Therefore, there is a great interest in exploring low-grade zinc oxide sources which contributes to the sustainable development of domestic metallurgic industry. In this paper, zinc is leached from low-grade zinc oxide ore and the optimum conditions have been figured with hydrometallurgical processing. Activated zinc oxide is also prepared from leaching solution via purification, precipitation and calcination.The mineralogical characters of the low-grade zinc oxide ore are studied. The results show that the main zinc minerals are smithsonite and hemimorphite. Based on this, H2SO4 and NH3·H2O-NH4HCO3 solutions are used to leaching Zinc from Zinc oxide ore, respectivly. The influence on the leaching rates of zinc including reaction time, temperature, concentration of leaching agent, particle size and liquid-solid ratio are investigated and screened out. Under the best conditions which are fixed by these single factor optimizing experiments, the leaching rates of Zinc which are 86.0% and 87.2% in the two different leaching agents, respectively. It can be dramatically promoted to 94.0% and 95.9% via two stages leaching process.The solution of acid leaching is purified containing two steps which are de-ironing reaction and replacing reaction, while that of ammonium leaching solution includes only replacing reaction. The results of leaching and purifying prcesses indicate that ammonium leaching process takes the advantages of lower concentration of silicon in leaching solution, less variaties of metalline impurity and advantages of simplified process, low power consumption and environmetal friendliness.In order to obtain highly actived zinc oxide, experiments of factors influencing particle size of activated zinc oxide are studied systematically. The optimum processes are as follow:the distilling ammonia time is 2.Oh, temperature is 120℃, aging time is l0min and the calcination time is 0.5h。And the calcination temperature is 350℃based on the DTG-TA analysis of zinc subcarbonate. Results show that properties of the product well agree to the Industry Standard of Chemical Engineering HG/T 2572-2006.