Solvent extraction of gallium from an Indian Bayer process liquor using Kelex-100

Abstract

Solvent extraction of gallium from a concentrated Indian Bayer process liquor was studied using 7-alkyl-substituted-8-hydroxyquinoline (Kelex-100) as an extractant and iso-decanol and kerosene as a modifier and a diluent, respectively. The composition of the Bayer process liquor was found to be ~450 gpl of Na₂O, ~80 gpl of Al₂O, and 190±20 ppm of gallium. The recovery percentage and the kinetics of extraction are improved by increasing the concentration of Kelex-100 in the organic phase from 6 to 14 vol%. However, the initial rate of extraction was slowed down at 16 and 18 vol% of Kelex-100. The initial rate of extraction was found to be improved by reducing the iso-decanol volume from 12 to 6% at 12 vol% of Kelex-100. The sodium and aluminium up take of the organic phase was found to be decreased with a decrease in the volume percent of iso-decanol. Minor additions of petroleum sulfonate improves the kinetics of gallium extraction significantly. The scrubbing of the loaded organic phase was found to be best at 6.0M HCl with a 1.0:1.5 organic to aqueous ratio, whereas, stripping was found to be best at 1.5M HCl with a 1.0:1.0 organic to aqueous ratio.