source:Journal of Sustainable Metallurgy
Himanshu has conducted in-depth research on the recovery of Ti, Al and RE (Sc, Y, La and Ce) from bauxite slag by sulphation roasting process.
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 concen-
tration affects the process economics.
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 ele-
ments are recovered as high-purity (> 99.5%) TiO2 and Al2(SO4)2.14H2O, whereas Sc and Y are concentrated into a liquid
solution for downstream recovery with solvent extraction.
In their paper, a two-stage leaching process with hydrochloric acid and oxalic acid was reported for selective recovery of Fe in the form of high-purity magnetite from bauxite residue. The previous process generated a residue consisting of Ti and RE with a concentration upgrade up to fourfold.
But most importantly,The present study is focused on the recovery of Ti, RE (Sc, Y, La, Ce), and Al from the following residue. The proposed process is based on sulfation baking and leaching for the dissolution of metal values. Downstream separation of dissolved elements is performed with hydrolysis, crystallization, and solvent extraction to recover highpurity products. The process chemistry is briefly elucidated based on kinetic and thermodynamic analysis, followed by experimental evaluation and validation. The proposed process provides better selectivity, high recovery rate, and purity of the final product and results in large volume utilization of bauxite residue with value recovery.
https://link.springer.com/article/10.1007/s40831-023-00678-1?