ANALYSIS OF LEAD AND ZINC SELECTIVE EXTRACTION PROCESS FROM EAF DUST DURING CARBOTHERMIC REDUCTION

The selective carbothermic reduction process of lead and zinc oxides from electric arc furnace (EAF) dust in the laboratory horizontal tubular electric furnace in an argon medium with excessive consumption of reducing agent (20 wt.%) during step heating with an exposure for 1 hour at each stage is analyzed. It is established that successive heating and exposure of EAF dust and a reducing agent mixture at temperatures of 1100 and 1200 °C led to the removal of 96.8 and 99.9 rel.% of lead and zinc respectively from the dust. At the same time, iron content in the residue increased to 61.7 wt.%. It is calculated that the introduction of 15.5 wt.% carbon as a reducing agent is sufficient for the reduction of oxides in the considered EAF dust sample. It is experimentally confirmed that when condensate is deposited directly on gas outlet tube in the furnace in an inert medium, the product obtained is mainly in metallic form, while cooling the condensate in traps outside the furnace leads to the formation of lead and zinc oxides, which indicates the oxidation of the material during condensation with air access. The data of X-ray spectral microanalysis of condensate obtained in the furnace in an inert medium indicated the possibility of evaporation from EAF dust no more than 25 rel.% of lead oxide in the gas phase without prior reduction, as well as the fact that lead selective extraction from EAF dust with minimal associated zinc extraction should be carried out at temperatures below 1100 °C.