Extraction of gadolinium and neodymium from tayan red mud

Red mud is a waste generated from the alumina production process. Red mud was previously categorized as hazardous waste due to its high alkalinity. In general, the mineral composition of red mud consists of Fe2O3 (30-60%), Al2O3 (10-20%), SiO2 (3-50%), Na2O (2-10%), CaO (2-8%) and TiO2 in amounts no greater than 25%. This composition varies widely around the world depending on the origin of the bauxite and red mud characterization results also have a rare earth element content of at least 0.03%. Rare earth element is classified as a critical metal, i.e. an essential material used and subject to supply risks as demand increases over time. Indonesia already produces at least 4.4 million tons of red mud per year, so more and more REY will be wasted if we do not utilize the existing red mud. Laboratory-scale experiments were conducted to recover gadolinium and neodymium from Tayan red mud in sulfuric acid in atmospheric pressure acid leching condition. Maximum recovery of gadolinium (91.3%) was recorded with 3 M H2SO4 at 90°C, solid/liquid ratio of 1/15 g/L and agitation rate of 700 rpm in 2 hours. While 81.5% neodymium recovery was achieved at 90°C and solid/liquid ratio of 1/15 g/L in 2 M H2SO4.