Abstract
This study investigates a two-stage duplex process for producing low-carbon ferrochrome based on sequential mixing of molten ore–lime and metallic melts, with emphasis on its adaptation to the raw materials and operating conditions of the Aktobe Ferroalloy Plant. Unlike the conventional process, in which the chromite ore–lime charge directly interacts with ferrosilicochromium, the proposed approach distributes FeSiCr between two successive stages of melt interaction to improve chromium reduction and metal–slag separation. Kempirsai chromite ore, lime, and ferrosilicochromium (FeSiCr 48) were used as raw materials. Thermodynamic analysis using HSC Chemistry 6.0 confirmed the feasibility of the main reduction reactions at 1600–1800 °C. Pilot-industrial trials produced ferrochrome containing 71.42–73.15% Cr and 1.28–1.31% Si, while the final slag contained 1.54–1.58% Cr2O3 and 0.11–0.14% FeO. X-ray diffraction analysis identified merwinite, gehlenite, and spinel-type solid solutions containing chromium. Dicalcium silicate was not detected, consistent with the observed stone-like structure of the cooled slag. Chromium recovery reached approximately 70%, compared with approximately 65% for the conventional process. The results demonstrate the potential of sequential FeSiCr distribution to improve chromium utilization and reduce chromium losses to slag under the specific conditions of ferrochrome production at the Aktobe Ferroalloy Plant.