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

Alkanoyl oxines have been used for the extraction of gallium from basi c solution, especially for the selective recovery of gallium in the pr esence 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 syn thesized by the Fries rearrangement from the corresponding acid chlori de and sodium oxinate using AlCl3 as catalyst. The synthesized alkanoy l 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 w as studied as a function of pH, temperature, time, metal concentration , phase separation acid (undecanol) concentration; and the strippabili ty as a function of HCl concentration. Based on these results, a seque ntial procedure for the selective separation of Ga from alkaline Bayer process liquor has been developed.