China Nonferrous Metallurgy

In this paper, the defluorination and dechlorination process of zinc-containing dust by side-blown melting was studied. The four-element ZnO-Fe₂O₃-CaO-SiO₂ slag type was calculated using the thermodynamic software FactSage. The impact of melting temperature on the viscosity and fluidity of the side-blown slag was further investigated. The distribution and trend of Zn, Pb, F, Cl, Ag and other key elements in the side-blowing smelting process were obtained through the analysis and detection of key elements in the smelting products. The experimental results demonstrate that under conditions of natural gas injection heating, the iron-silicon ratio (Fe/SiO₂) was 1, the calcium-silicon ratio (CaO/SiO₂) was 0.5, the melting effect of molten slag wasoptimal when the melting temperature exceeded 1400℃. When the melting temperature wasbelow 1400℃, the slag exhibited suboptimal melting properties. The primary phases identified in the slag produced by the side-blowing smelting process were Ca₂ZnSi₂O₇, Fe₃O₄, Zn₂SiO₄ and ZnFe₂O₄, and the primary phases observed in the side-blowingdustwere ZnO, NaCl, KCl and K₂ZnCl₄. After the side-blowing melting process, the fluorine content in the slag was reduced to 0.057%, with a fluorine removal rate in the raw material exceeding 85%. The chlorine content in the slag was reduced to 0.0091%, and the removal rate of chlorine in the raw material exceeded 99%. In this paper, the feasibility of side-blowing smelting process for treating zinc-bearing dust was preliminarily verified by using 0.28m² side-blowing furnace expansion test device, which provides a new approach for domestic and foreign enterprises seekingto treat zinc-containing dust in alignment with the strategic goal of double carbon emission reduction.