Selective extraction of carbon-free zinc and lead from EAF-dust
Izvestiya Visshikh Uchebnykh Zavedenii Chernaya Metallurgiya = Izvestiya Ferrous Metallurgy
In electric-arc furnace dust zinc content can reach 43 %, lead content can reach 4 %. The content of ecotoxicants such as dioxins and furans (D&F) adsorbed on dust particles achieve 500 ng/kg of dust. Generally, zinc and lead are reduced from their oxides by dint of carbon (an average of 500 kg/t dust). The results of thermodynamic calculations and experimental studies have shown that these metals can be extracted from dust without the participation of carbon or at its low content (less than 3
... ntent (less than 3 %) . Temperature of about 1400 K is required to extract lead, and about 2000 K is required for zinc extraction. The temperatures of their extraction depend on the dust composition, in particular, on the content of carbon, chlorine and the O/C ratio . They can also depend on phase and dispersed composition of the dust. A physicochemical analysis of the dust formation processes in electric arc furnaces (EAF) has been carried out, the composition and properties of dust have been investigated, and experimental studies of the zinc and lead selective extraction process in laboratory conditions have been leaded. A dust processing technology has been developed and the possible innovative potential of the expected results has been assessed. The approaches we propose are based on the study of a continuous two-stage process of carbon-free and zinc and lead selective extraction from EAF dust of different composition. One of the main results of the work, along with the creation of a technology that ensures the selective zinc and lead extraction up to 99 %, is the development of a process for neutralizing EAF dust from D&F to an environmentally safe level.