Processing copper slag flotation tailings via hydrofluoride sintering to recover amorphous silica and hematite

Flotation tailings from dump copper smelting slags represent a large-tonnage, finely dispersed waste product of copper smelting, currently stored in proximity to processing plants. Partial utilization of this waste in construction for producing concrete or abrasives does not address the issue of its large-scale accumulation and the associated environmental consequences. The tailings consist of silicates-fayalite, pyroxene, and iron-containing glass. The content of copper (up to 0.5%), zinc (up to 4%), iron (up to 35%), and silicon (up to 50%) allows this waste type to be considered a promising technogenic raw material for obtaining not only non-ferrous metals but also other types of marketable products. This paper proposes a novel method for processing the flotation tailings, based on hydrofluoride sintering to destroy the silicate phases. The experimental results demonstrate the feasibility of separating the main components of the raw material to obtain amorphous silica and a hematite residue, which are marketable products (e.g., catalysts, materials for paint and varnish industry, sorbents).