Verfahren zur Gewinnung von Gallium oder Indium

Gallium and/or indium are produced by working up a residue from the preparation of an alkyl aluminium sesquihalide by reacting aluminium with an alkyl halide, or a residue from the preparation of an alkyl aluminium hydride or trialkylaluminium compound according to the following reaction scheme: wherein p and T represent elevated pressure and temperature, respectively, and n is an integer. The residues may be worked up by any method known per se. Thus there may be used physical methods of separation, e.g. evaporation, distillation, sublimation, flotation, centrifugal separation, and methods which take advantage of differences in magnetic properties and differences in density, for example, fluidized bed techniques; and chemical methods of separation, e.g. selective oxidation, amalgamation, electrochemical methods, and methods which make use of differences in the solubility of the components of the residue in various solvents. A preferred method for producing gallium, however, comprises drying the residue, reacting the dried residue with a halogen or a hydrohalide to form gallium halide in admixture with the halides of other elements present in the residue, separating the volatile halides which include gallium halide, from the mixture of halides, and treating the volatile halides with a non-aromatic hydrocarbon to preferentially dissolve the gallium halide, the gallium halide solution thereafter being treated in a manner known per se to recover gallium. The gallium may be recovered by distilling off the solvent, and hydrolysing in an alkaline medium the gallium halide remaining. In the above process, the indium halide may be separated from the mixture of halides remaining after the gallium halide has been separated, by making use of the differences in solubility of the halides in ethers, and the separated indium halide then worked up into indium.