Recovery of rare earths from bauxite residue slag by high-pressure acid leaching

The recovery of rare-earth elements from an alumina and silica rich slag produced during the smelting reduction process of bauxite residue was studied. The slag was leached with sulfuric acid at different concentrations (1-3 N H2SO4) in a titanium autoclave at a liquid-to-solid ratio of 10:1 and different temperatures (100-180 °C). The dissolution of rare-earth elements increased with increasing acid concentration, but it decreased with increasing temperatures. About 95 wt% of the scandium could be extracted with 3 N H2SO4 at 100 °C, while about 87 wt% yttrium was extracted under the same conditions. Neodymium and lanthanum yields were about 45-60 wt%. Temperatures above 100 °C lead to a high selectivity of scandium over the other rare earths (i.e. yttrium, neodymium and lanthanum).

ISBN:9789082825923

Publication year:2018

Accessibility:Open