Recovery of Scandium by Leaching Process from Brazilian Red Mud

Alumina is the rawmaterial for aluminum production, where it is obtained from bauxite by the Bayer Process. Sodium hydroxide is used in a pressure digestion with to obtain an aluminate solution and then remove impurities by the precipitation. For each 1 ton of alumina produced, 1-1.25 tons of red mud is generated in the Bayer Process. Red mud is mainly composed of iron, silicon and titanium oxides, but rare earth elements (REEs) can also be found in the residue. The most important REE is scandium, because it is 90% of the price of all REEs present in red mud. The aim of this work was to study a leaching process of Brazilian red mud to obtain scandium. Sulfuric acid 20wt% was used as leaching agent, L/S ratio 1/10 (please add unit), temperature of 25 degrees C and 6 h of reaction time. Samples were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD).