Title: In-Situ Alkali Activation Of Copper Smelting Slag During Pouring: Thermodynamic And Morphological Effects On Fayalite Decomposition
Authors: Mutalibkhonov S.S. Musurmankulova A.S.
Volume: 10
Issue: 7
Pages: 177-182
Publication Date: 2026/07/28
Abstract:
- Copper smelting slags are commonly characterized by a fayalite-based structure (Fe?SiO?) that encapsulates valuable metals such as Cu, Au, and Ag, making their recovery difficult by conventional flotation and grinding. This study investigates an innovative in-situ modification approach in which sodium hydroxide (NaOH) or sodium carbonate (Na?CO?) is added directly into molten copper slag during tapping from the slag mixer into slag ladles. The intense barbotage and mixing between molten slag and alkali additives promote the decomposition of fayalite into FeO and sodium silicate (Na?SiO?). Thermodynamic calculations based on Gibbs free energy and Ellingham diagrams confirm the feasibility of fayalite destabilization at operating temperatures of 1200-1250 °C. Microstructural analysis demonstrates a transition from dense fayalite matrices to porous and softened slag morphologies. This transformation significantly improves subsequent comminution efficiency by reducing ball mill wear and enhances flotation recovery through the dissolution of Na?SiO? in aqueous media. As a result, liberation of entrapped precious metals (Au, Ag, Cu) is substantially improved. The proposed process provides a low-cost and industrially feasible route for copper slag valorization and green metallurgy.