Zinc extraction during recycling of electric arc furnace dust by chlorine-containing polymer wastes

Abstract

From an environmental point of view, dust from the melting of galvanized steel scrap in electric arc furnaces is a prob-lematic waste stream. In particular, it is impossible to store dust in open areas due to high content of toxic components (lead, zinc, cadmium, etc.). At the same time, the extraction of non-ferrous metals from electric-arc melting dust can make it a valuable source of secondary raw materials and reduce the impact on the environment. In a laboratory study, zinc was extracted from electric arc smelting dust by a chlorination method with a waste halogen-containing polymer. Roasting of galvanized scrap melting dust together with polyvinyl chloride (PVC) waste as a chlorination agent at 950 °C resulted in the evaporation of about 80 wt.% zinc in an oxidizing atmosphere and more than 95 wt.% zinc in a neutral atmosphere. The use of PVC waste in the firing process provides the release of gaseous HCl, which is an effective reagent for the chlorination of zinc compounds in dusts. The presence of solid carbon from polymer pyrolysis in the mixture accelerates the course of chlorination reactions, which is confirmed by the thermodynamic calculations given above. Energy dispersive X-ray spectroscopy of the cinder obtained by roasting at 950 °C in a neutral atmosphere showed that the dry residue of the material in the proposed process does not contain zinc. © Bludova D. I., Mamyachenkov S. V., 2023.