Additional Extraction of Aluminum and Silicon During Integrated Bauxite Processing in Kazakhstan

In this paper, we experimentally investigated the integrated processing of high-iron Kazakh bauxites by reducing smelting of ore–coke–lime briquettes to produce an Fe-Al-Si metallic alloy, which is of potential interest for steel deoxidation, together with calcium-aluminate slag, which is of potential interest for alumina extraction. Briquettes containing bauxite, metallurgical coke (10–20 wt.%), and freshly calcined lime (10 wt.%, constant) were melted in a muffle furnace at a temperature of 1200–1450 °C. Complete separation of metal and slag was achieved at 1400–1450 °C, whereas at 1200–1350 °C, separation remained incomplete. Changing the coke/bauxite mass ratio in the charge from 0.125 to 0.286 increased the total content of metallic Si, Al and Fe in the recovered metallic product from 77.1 to 98.66 wt.%, according to X-ray fluorescence (XRF) analysis after two-stage magnetic separation; the metallic product obtained with a coke/bauxite ratio of 0.286 in the charge contained 72.8% Fe, 23% Al and 2.86% Si (with minor impurities of Ti, Mn and Cr), while the associated slag was represented mainly by CaO (59.5%) and Al2O3 (34.0%). These slag characteristics indicate its potential suitability for alumina extraction or as a filler for structural concrete. The proposed route represents a potentially low-waste alternative for processing high-iron bauxites that are poorly suited to the classical Bayer process, avoiding the direct formation of red mud and supporting Kazakhstan’s transition toward closed-loop bauxite processing.