Method of producing aluminium oxide from aluminium sulphide or mixtures containing same

摘要

294,079. Metallbank und Metallurgische Ges. Akt.-Ges., and Girsewald, Conway, Baron von. Jan. 27, 1928. Alumina; calcium sulphide. - Aluminium sulphide, or a mixture thereof with alumina resulting for example from an eleotrothermic process for extracting alumina from aluminiferous materials, is reacted with calcium oxide or a calcium compound such as the carbonate to convert the sulphide to oxide, and the calcium sulphide formed is removed from the product by leaching as with a dilute acid. A mixture of the solid sulphide and calcium oxide may be heated say to 800-900‹ C. and carefully stirred, the reaction being then completed by the heat of reaction; or a melt of the sulphide or of a sulphide-oxide mixture may be run on to powdered calcium oxide with stirring. In the first case the product is boiled first with water and then with hydrochloric acid, and in the second washed with dilute acid, to remove the calcium sulphide.