Selective Recovery of Scandium from Nickel Laterite Ore by Acid Roasting–Water Leaching

Scandium is a rare and expensive metal that is in increasing demand because of its unique properties. Laterite ore is known to contain scandium in appreciable amounts. In this study, a two-stage process called “acid roasting–water leaching” was developed to extract scandium from laterite ore with minimal co-extraction of iron. In this process, the ore was mixed with concentrated sulfuric acid (98 wt%) and roasted in a furnace at or above 600 °C. The roasted ore was then leached in water at ambient conditions. During acid roasting, Fe₂(SO₄)₃ is decomposed to Fe₂O₃, which is insoluble in water, and thus it can be separated during the leaching process. A fractional factorial design methodology was utilized to investigate the effect of various operating parameters during the roasting and leaching processes and to optimize the processes. After optimization, 80% of scandium was recovered with less than 15% co-extraction of iron.