Recovery of scandium from Sc-bearing aegirine by Na2CO3 roasting-water washing-H2SO4 leaching process

As one of the most valuable rare earth elements in Bayan Obo tailings, scandium is a vital material broadly used in the fields of aerospace, glass ceramics, petrochemical, and agriculture. As scandium was found primarily in silicate minerals such as aegirine and amphibole in the Bayan Obo rare earth deposit, in order to utilize scandium in aegirine mine, a novel Na2CO3 roasting-water washing-H2SO4 leaching process (NRWHLP) was proposed. This process was found to be feasible based on the results. During the roasting process, scandium entered the NaFeO2 phase which is easily hydrolyzed to a reactive ferric hydroxide phase. In the optimal reaction conditions: roasting with a Na2CO3-to-aegirine molar ratio of 3.2:1 for 150 min at 750 °C, washing twice at 80 °C, leaching with a L/s = 4 and 8 mol/L H2SO4 for 30 min at 80 °C, scandium leaching efficiency can be above 97 %. This study will provide a novel process for the exploitation of scandium and a theoretical basis for future industrial applications of the Bayan Obo rare earth tailings.