Recovery of scandium and aluminum from limonitic laterite intermediate product

The discovery of Sc-rich Ni-Co laterite highlights the potential of the extraction of Sc from Ni-Co laterite. In the nitric acid pressure leaching (NAPL) process of treating limonitic laterite, Sc precipitates with Al and concentrates in Sc-bearing Al residue. Thus, this intermediate product becomes an important resource for Sc. This paper presents a combined process to recover Sc and Al from Sc-bearing Al residue, which consists of alkaline leaching, acid leaching and solvent extraction. First, by controlling alkalinity, 94.3% Al was separated from the Sc-bearing Al residue, while 96.8% Sc was enriched in leach residue. Then, the obtained Sc-rich residue was totally leached with sulfuric acid. Moreover, Sc in leach solution was synergistically extracted by 10% Di-(2-ethylhexyl) phosphoric acid (P204) and 5% Tributyl phosphate (TBP). Finally, the co-extracted impurities in the Sc-loaded organic phase were scrubbed by HCl solution, followed by the Sc was stripped with NaOH solution. Sc-bearing Al residue is an advantageous Sc resource, and the proposed process could achieve comprehensive utilization of Sc-bearing Al residue in a facile way.