ELECTROLYTIC EXTRACTION OF GALLIUM FROM ALKALI METAL ALUMINATE INCLUDING TWO-STAGE CARBONATATION

摘要

Alkali metal aluminate solutions are subjected to two-stage carbonatation with stirring to produce aluminium hydroxide, a gallium-containing precipitate, and solutions containing caustic and alkali metal bicarbonate. Thereafter the produced gallium-containing precipitate is mixed with a solution containing caustic alkali until the content of gallium in the solution is 0.05 to 1 g/l. Any precipitate formed is separated and the solution enriched with gallium is mixed with a solution containing alkali metal bicarbonate. The resulting mixture is subjected to evaporation to separate alkali metal compounds, and the solution which has been subjected to evaporation is carbonated to produce a solution containing alkali metal salts, and a gallium concentrate from which gallium is produced by transforming it into an alkaline solution from which metallic gallium is recovered, either electrochemically, such as by electrolysis, or by reduction with an aluminium-containing gallium alloy. The proposed method makes it possible to extract gallium at a comparatively low cost from solutions obtained in the processing, for example, of nephelines containing it in amounts which do not exceed 0.02 to 0.03 g/l. As a result of the proposed method, it has become possible in the processes of concentration of gallium to produce a number of valuable components such as alkali metal salts contained in the starting ore.