Theoretical and experimental assessment of the feasibility of producing ferroalloy from lead-zinc ores and leaching cakes of vanadium-containing quartzites

The article provides the findings of both theoretical and experimental investigations aimed at identifying the optimal process parameters that maximize the extraction of silicon and non-ferrous metals from a mixture of sulfide ore and sulfuric acid leaching cakes of vanadium-containing quartzites. This process results in the production of a ferroalloy and sublimates enriched with zinc and lead. Utilizing a method of computer thermodynamic modeling predicated on the minimization of Gibbs free energy, the effect of the quantities of coke and steel chips on the silicon extraction into the ferroalloy, as well as zinc and lead into the sublimates, was analyzed. The optimal processing parameters for the ore and cake mixture through electric smelting were established employing the method of second-order rotatable designs (Box-Hunter Design) within a single-electrode arc furnace. Under equilibrium conditions in the examined system, with 18% steel chips and an augmentation of coke from 20 to 25%, the silicon extraction degree into the alloy escalates from 62.95% to 70.98%. With 23% coke and a variation in steel chips quantity from 6% to 30%, the silicon extraction degree into the alloy increases by 13.79%, from 59.97% to 73.76%. Ferrosilicon of the FeSi45 grade – yielding the extraction degree of 64.2% to 73.1% Si – is formed in the presence of 8.8% to 19.3% steel chips and 18.0% to 26.0% coke, while the FeSi50 grade – yielding the extraction degree of 62.5% to 67.3% – is achieved with 6.0% to 11% steel chips and 18% to 26% coke. During the electric smelting of a mixture comprising 12% magnetite concentrate and 22% coke, three grades of ferrosilicon were produced: FeSi25 (with 30% steel chips), FeSi45 (with 18% steel chips) yielding the silicon extraction degree of 72.4% to 80.6%, and FeSi50 (with 6% steel chips) with the silicon extraction degree of 69.3% to 74.5%. Furthermore, 98.2% to 98.6% of these metals are extracted into sublimates containing 25.2% zinc and 13.7% lead.