Stabilization of Self-Disintegrating Refined Ferrochrome Slags Using Desulfurized Borate Ore from the Inder Deposit: A Comparative Study with Colemanite

The production of refined ferrochrome is accompanied by the formation of self-disintegrating slags caused by the β→γ-Ca2SiO4 polymorphic transformation during cooling, resulting in environmental and technological problems. This study aimed to develop and validate a technology for long-term stabilization of refined ferrochrome slags using remelted and desulfurized borate ore (RDBO) from the Inder deposit as an alternative to colemanite. Thermodynamic modeling, X-ray diffraction (XRD), scanning electron microscopy (SEM), and pilot-industrial trials were conducted to evaluate phase transformations, microstructure formation, and slag stability. The results showed that the addition of boron oxide promoted the formation of stable borate phases, primarily CaB4O7, and reduced the content of unstable Ca2SiO4 phases. Autoclave testing under saturated steam conditions (400 kPa, ~180 °C, 24 h) demonstrated complete preservation of structural integrity in all RDBO-stabilized samples, with an average mass loss of 0.19 ± 0.01%, whereas colemanite-stabilized slags exhibited cracking and partial disintegration. The stabilization effect was achieved at a B2O3 content of 0.17–0.47 wt.% without boron contamination of ferrochrome. The proposed technology ensures long-term slag stability and enables the utilization of stabilized slag as a technogenic material for road construction.