Separation of Scandium by Phosphinic Acid Extractant from Sulfuric Acid Solution

The main challenge for scandium extraction from bauxite residue by hydrometallurgy is the separation step. After sulfuric acid leaching, the solvent extraction process is required for a high separation degree. The presence of contaminants such as iron and aluminum in a concentration 1000 times higher than scandium is a problem to be overcome. The present study aims at the separation of scandium from the sulfuric acid solution using Cyanex 923 in kerosene. First, zirconium was removed using Aliquat 336. Then, Cyanex 923 was used to remove scandium over impurities, such as iron, aluminum, and titanium. Results have demonstrated that the pH does not affect scandium separation, while temperature, organic extractant concentration, and TBP affect the separation. Experiments were carried out for 15 min under magnetic stirring, and samples were analyzed in EDXRF and ICP-OES.