Separation and recovery of iron and scandium from acid leaching solution of red mud using D201 resin

Red mud is a byproduct of alumina refining of bauxite ores, and is a significant source for extracting scandium. However, a large amount of iron in red mud makes it difficult to recover scandium because Fe(III) and Sc(III) have similar physicochemical properties. In this study, a new method was developed for selective separation of iron and scandium in acid leachate of red mud using D201 resin. Theoretical calculations indicate that the ferric species mainly exists as FeCl 3 or FeCl 4 − at chloride concentration above 6.65 mol/L, while scandium still exists as ScCl 2 + , making it possible to selectively separate iron from scandium through anion resin adsorption. The factors affecting the adsorption of iron and scandium such as chloride concentration, resin dosage, adsorption time, and temperature were evaluated in batch experiments. The Langmuir model was successfully applied to both iron and scandium adsorption, and the maximum adsorption capacities of iron and scandium are 147.06 and 0.95 mg/g, respectively, indicating a significant difference between iron and scandium. Raman analysis further demonstrates that the iron is adsorbed onto D201 resin as FeCl 4 − anion. In chloride-rich solution, Fe(III) existed as FeCl 4 ‒ or FeCl 3 species, both of which could be efficiently adsorbed by D201 resin, while scandium remained as ScCl 2 + in the solution. • A new approach was proposed for the separation of Fe and Sc from red mud. • The forms of Fe(III) and Sc(III) species in high concentration chloride solution were clarified. • Iron ions can be effectively removed from red mud by D201 resin with low scandium loss. • Iron ions in the resin can be easily eluted by dilute hydrochloric acid.