GB968334A - Process for the extraction of gallium and indium from anode slime - Google Patents

Abstract

Gallium and indium are recovered by working up the anode slime which is formed in an electrolytic process employing aluminium or an aluminium alloy as anode, and an organometallic complex salt melt or solution as electrolyte. Methods of working up which may be used include physical methods of separation, e.g. evaporation, distillation, sublimation, flotation, centrifugal separation and methods which make use of differences in magnetic properties, for example fluidized bed methods of separation, and chemical methods of separation, e.g. selective oxidation, amalgamation, electrochemical methods and methods which make use of differences in the solubility of the various elements in different solvents. A preferred and novel method for separating the gallium, however, comprises drying the anode slime, reacting the dried slime with a halogen or hydrohalide to form a mixture of halides, separating the volatile halides including gallium halide from the non-volatile halides, treating the volatile halides with a non-aromatic hydrocarbon solvent to selectively dissolve the gallium halide, recovering the gallium halide from the resulting solution and working up the gallium halide into gallium, e.g. by electrolysis in an alkaline medium. In the example the mixture of indium and aluminium chlorides remaining after the removal of gallium trichloride by the above method is separated by making use of the great difference in the rate of solution of the two halides in ethers.