Caustic Soda Leach of Electric Arc Furnace Dust


Abstract: The annual process dust output of Turkish EAF steel plants is approximately 120,000 t. EAF dust contains about 15-35 % Zn and some toxic metals such as Pb, Cd and Cr. It is well known that EAF dust is used as a substitute for zinc ores in many countries. Turkey imports about 25,000 tonnes of metallic zinc to meet its demand (about 50,000 t/y) mainly due to the shortage of zinc ores. Therefore, the recycling of Turkish EAF dust could contribute greatly to the economy. In this study, caustic soda leach experiments were conducted with an EAF dust sample containing 23 % Zn, 5 % Pb and 30 % Fe obtained from by a plant located in Aliağa/İzmir. Optimum leach conditions were determined. Extraction yields for Zn and Pb were 80 % and 85 %, respectively. The relatively low Zn extraction yield was mainly due to the presence of insoluble zinc ferrite (ZnFe_2O_4). The bulk leachate was cleaned using zinc powder to precipitate lead and other impurities. After solid/liquid separation, zinc metal with 99.27 % Zn was recovered by electrolysis of the purified solution. These experiments indicated that the caustic soda leach-electrolysis process may be technically applicable to Turkish EAF dust.

Keywords: Zinc, dust, leach, electric arc furnace

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