Process for the manufacture of purified oxide aluminum from alumina mineral

摘要

1,158,154. Aluminium oxide. PECHINEYCOMPAGNIE DE PRODUITS CHIMIQUES ET ELECTROMETALLURGIQUES. 10 Aug., 1966 [10 Aug., 1965], No. 35813/66. Heading C1A. Aluminium oxide, with a reduced content of impurities iron, silicon and titanium in elementary or combined form, is produced by contacting aluminous material such as bauxite containing silica, iron and titanium oxides with carbon and sulphur at a temperature rising from a minimum in the range 200 to 1000‹ C., to a maximum in the range 1200 to 1500‹ C., particularly 1200 to 1350‹ C. The product may be chlorinated with C1 2 , 5C1 2 or SO C1 2 at 200‹ to 900‹ C., preferably 500‹ to 700‹ C. to remove the elementary impurities as chlorides and finally treated with oxygen, pure or diluted, at 600- 1500‹ C. to remove excess carbon. The quantity of carbon used is between 1 and 1À25 times the amount necessary to reduce the oxides of iron, titanium and silicon to theelementary state. The quantity of sulphur used is at least equal to the amount necessary to convert silicon to silicon monosulphide, and at the most equal to 1À6 times the quantity necessary to convert the silicon, iron and titanium to higher sulphides, the oxygen combined with iron and titanium being removed as sulphur dioxide.