Modeling and optimization of electric smelting parameters for ferrosilicon production from vanadium quartzite leaching residue and coal flotation tailings

Silica-rich quartzite leaching cakes and carbon-rich coal beneficiation tailings represent promising technogenic raw materials. Therefore, these cakes and tailings can be considered alternatives to natural raw materials for ferrosilicon production. This article presents the results of a study that examined the feasibility of using coal flotation tailings as a carbon-containing reducing agent for ferrosilicon production from vanadium quartzite leaching cakes. This study was conducted using thermodynamic modeling with the HSC Chemistry software package, electric smelting of the charge in induction and arc furnaces, and second-order rotatable planning. On the basis of these data, vanadium quartzite leaching cakes and coal flotation tailings were found to be suitable raw materials for producing various grades of ferrosilicon. The optimal conditions for the electrothermal production of FeSi45 ferrosilicon with a silicon extraction rate of 71.6–88.5% are a filter cake-to-tailings ratio of 1.0–3.25 and a steel cutting content of 20–32%. For the production of FeSi50 ferrosilicon, the optimal filter cake-to-tailings ratio is 1.0–1.37, with a steel cutting content of 20.0–22.2%. The feasibility of smelting FeSi45 ferrosilicon, containing (by mass) 43.4% Si, 1.54% Al, 0.32% Ca, 0.43% Mn, 0.17% Cr, 0.12% Ti, 0.11% V, 0.5% C, 0.05% Ni, 0.038% P, and 0.034% S, with a silicon extraction rate of 81.6%, was confirmed through pilot-scale electric smelting in an arc furnace.