THE ROLE OF HYDROMETALLURGY IN THE RECYCLING OF ZINC, COPPER AND LEAD
Abstract
Metals recycling remains an important industrial activity for both economic and environmental reasons, and the role of hydrometallurgical processing in the recycling of zinc, copper and lead is discussed. Hydrometallurgical processes are being developed to leach zinc from galvanized steel scrap prior to remelting, and both alkaline and acid leaching technologies are being evaluated to eliminate zinc from electric arc furnace (EAF) dusts prior to their recycle. The high halogen content of the dusts, however, suggests that chloride-based systems, such as the EZINEX or Terra Gaia processes, could be especially useful for this material. Most copper scrap is melted, fire refined and cast into anodes for electrorefining. An understanding of the behaviour of the diverse impurities present in secondary copper anodes and their controlled rejection to the anode slimes generated during electrorefining are critical to the production of high quality cathode copper. Hydrometallurgy plays an important role in the treatment of the paste component of spent lead-acid batteries; a carbonate leach is widely used to eliminate the sulphate fraction of the paste, thereby avoiding SO2 gas emissions in subsequent smelting operations. The role of hydrometallurgy could be expanded if stable anodes could be developed to allow commercial implementation of the many leach-electrowinning processes under development for lead-acid battery paste.
Editors and press
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