SOLVENT-EXTRACTION OF GALLIUM(III) FROM BASIC SODIUM ALUMINATE SOLUTION BY ALKANOYL OXINES

Alkanoyl oxines have been used for the extraction of gallium from basic solution, especially for the selective recovery of gallium in the presence of excess aluminum from Bayer process sodium aluminate liquor. 5-Alkanoyl-8-hydroxy-quinolines (R.CO.Ox), where R is the alkyl group C13H27 (myristoyl), C15H31 (palmitoyl), and C17H35 (stearoyl) were synthesized by the Fries rearrangement from the corresponding acid chloride and sodium oxinate using AlCl3 as catalyst. The synthesized alkanoyl oxines were capable of extracting Ga into kerosene or chloroform at a pH around 13; the selectivity of Ga over Al was high at this pH. The extracted Ga could be stripped into the aqueous phase acidified with HCl without significant loss of the ligand. The extractability of Ga was studied as a function of pH, temperature, time, metal concentration, phase separation acid (undecanol) concentration; and the strippability as a function of HCl concentration. Based on these results, a sequential procedure for the selective separation of Ga from alkaline Bayer process liquor has been developed.