
Abstract During acid leaching of bauxite residue (red mud), the increase in dissolution of rare-earth elements (REEs) is associated with a substantial co-dissolution of iron; this poses problems in the downstream processing (i.e. solvent extraction or ion exchange). Six different slags generated by reductive smelting of the same bauxite residue sample were treated by high-pressure acid leaching (HPAL) with HCl and H2SO4 to selectively extract REEs. Thus, up to 90 wt% of scandium was extracted from the slags using H2SO4 at 150 °C, while with HCl the extraction of scandium reached up to 80 wt% at 120 °C. The extraction of yttrium, lanthanum and neodymium was above 95 wt% when HCl was used as a reagent, but it was much lower ( 90 wt%, 18 g L−1), while the concentration of the remaining iron (>60 wt%) was of 3 g L−1 in the leachate. The co-dissolution of silicon and titanium was lower than 5 wt%.
Technology, 0904 Chemical Engineering, 4019 Resources engineering and extractive metallurgy, Bauxite residue, 4004 Chemical engineering, VALUABLE METALS, Slag, Rare earths, High-pressure acid leaching, RED MUD, Mining & Metallurgy, SILICA, OPTIMIZATION, TEMPERATURE, KINETICS, Red mud, Science & Technology, Smelting, IRON, SCANDIUM, 0914 Resources Engineering and Extractive Metallurgy, RECOVERY, ALUMINUM, Metallurgy & Metallurgical Engineering
Technology, 0904 Chemical Engineering, 4019 Resources engineering and extractive metallurgy, Bauxite residue, 4004 Chemical engineering, VALUABLE METALS, Slag, Rare earths, High-pressure acid leaching, RED MUD, Mining & Metallurgy, SILICA, OPTIMIZATION, TEMPERATURE, KINETICS, Red mud, Science & Technology, Smelting, IRON, SCANDIUM, 0914 Resources Engineering and Extractive Metallurgy, RECOVERY, ALUMINUM, Metallurgy & Metallurgical Engineering
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