아연 더스트로부터 건·습식 융합 공정을 통한 고순도 산화아연 제조 연구

Abstract

Zinc dust is typically divided into zinc dross, an oxide formed on the top of molten metal in contact with outside air during the process of casting zinc and EAFD(Electric arc furnace steel dust) generated in the steelmaking process that removes impurities from steel. In 2018, it is known that about 6,300 tons of zinc dross and about 400,000 tons of EAFD are generated. Zinc dust contains about 30-50% Zn and contains a small amount of heavy metals, but it is treated as waste due to the absence of treatment technology or simply sold as dust scrap. To date, various processes for recovering zinc and zinc oxide from zinc scrap have been proposed, and representative processes can be divided into the Waelz Kiln method and the Plasma method. However, the Waelz kiln method produces zinc oxide with a high recovery rate, but it contains high impurities such as Pb, Cl, Na, K, and Fe, so the purity is low. The plasma method has the advantage of directly recovering metallic zinc by melting reduction, but has a disadvantage of low zinc purity. Therefore, in this study, nano-grade zinc oxide powder was produced through a dry and wet fusion process of zinc dross collected through a dust collector after being produced in a casting process using an electric furnace. The nano-sized zinc oxide powder recovery process includes vapor distillation to recover Zn by mixing zinc dross dust and coke, selective leaching of Zn(NO3)2 through the addition of HNO3, neutralization of NH3, water leaching to remove residual ammonium nitrate, and recovery of nano zinc oxide powder through drying. The vapor distillation process was maintained at 1200℃ for 3 hour in a zinc dross dust: carbon powder = 10:2 weight ratio. To recover the deposited Zn, keep the concentration of Zn and 30% HNO3 at room temperature in a 1:6 molar ratio, then neutralize by adding a concentration of 28% NH3 and wash 3 times for 1 hour to recover pure ZnO. Through the above process, 99.99% purity of zinc oxide, an average particle diameter of 150 nm, and plate-shaped ZnO nanopowder were finally recovered.