查看文章

High-silica bauxite is not used to obtain sandy-grade alumina owing to its low alumina/silica ratio (μ_Si < 3). Acidic methods, such as the use of HCl and NH₄HSO₄, show promise for treating this raw material. The leaching of boehmite-kaolinite bauxite from the Severoonezhsk deposit mine (Arkhangelsk region, Russia) using a mixture of NH₄HSO₄ and H₂SO₄ was investigated for the first time. The bisulfate method, which combines the advantages of the acidic and alkaline methods, involves bauxite leaching, precipitation of ammonium alum, recrystallization for gibbsite precipitation, and calcination for alumina production. The effects of temperature (130–200 °C), liquid-to-solid ratio (8–12), and duration of leaching (5–90 min) on the degrees of extraction of Al, and rare earth elements (REEs) were evaluated. The extractions of Al, Fe, and Ga were found to be >90%, with most of the silica and titania remaining in the …