Extraction of Titanium, Aluminum, and Rare Earth Values from Upgraded Bauxite Residue

The Bayer process for alumina production generates more than 160 million tons of bauxite residue annually. The current global stockpiles of bauxite residue have reached more than 4 billion tons with less than 2% annual recycling rate. Critical elements such as Sc and Y present an opportunity to explore bauxite residue as a secondary resource; however, low concentration affects the process economics. The following research focuses on the recovery of Ti, Al, and rare earth elements (Sc, Y, La, Ce) from upgraded bauxite residue obtained after Fe, Na, Ca, and Si separation. Recovery of major elements resulted in upgradation of Ti and RE values up to fourfold. Thermodynamic and kinetic aspects of the proposed recovery process are critically evaluated, and optimized conditions are reported to obtain high recovery of Ti, Al, and RE values. The major elements are recovered as high-purity (> 99.5%) TiO2 and Al-2(SO4)(2).14H(2)O, whereas Sc and Y are concentrated into a liquid solution for downstream recovery with solvent extraction.{GRAPHICAL ABSTRACT}