Industrial-Scale Production of Zinc Powder Using Alkaline Leaching-Electrowinning Processes

Abstract

An integrated process consisted of raw materials milling and grinding, leaching, purification, electrowinning, regeneration of the spent electrolytes, vacuum drying, analysis, etc. is developed, and the industrial application flow sheet is designed, with annual yield 1500–2000 tons metallic zinc powder. The process developed has been successfully applied at several plants with a scale of 1000, 1500, and 2000 tons of metallic zinc powder annually. The long-term industrial operations have been shown that the process can use any raw materials containing Cl, F, Si, Fe, As, Cu, etc. The total Zn content of zinc powder produced is over 98% and the metallic zinc content over 94%, which reaches the Class 2 of the national standards of zinc powder quality. Hence, the process is quite different to the acidic process and can apply the raw materials unacceptable for the acidic process. The life cycle assessment method is used to investigate the environmental impacts of the new alkaline processes of production of Zn powder. The results indicate that the environmental impacts of alkaline leaching-electrowinning technology are less than the conventional acid leaching hydrometallurgical processes and pyrometallurgical processes. The energy consumption, greenhouse effect, and acidification in the new processes are 87.76%, 47.80%, and 0.08% of those in the conventional acid leaching hydrometallurgical processes and are 93.94%, 9.25%, and 0.14% of those in the pyrometallurgical processes.