Abstract: Bauxite is reacted with spent caustic soda solution at 113.degree. C. to 205.degree. C. to produce a first pregnant liquor stream, a granular residue stream and a muddy substance stream wherein the granular residue stream is discarded, the muddy substance stream is reacted with or without a small portion of bauxite, but with a spent caustic soda stream at 206.degree. C. to 350.degree. C. to produce a second pregnant liquor stream and a red mud stream which is discarded; the first and second pregnant liquor streams are filtered, cooled to 50.degree. C. to 87.degree. C. and then seeded to precipitate alumina hydrate containing less than 0.017% Fe.sub.2 O.sub.3 by weight.

Abstract: A wet caustic aluminate process that comprises digesting a bauxite at a low temperature in caustic aluminate liquor to extract the alumina trihydrate, separating the supersaturated caustic aluminate liquor of low Fe.sub.2 O.sub.3 content from the mud, digesting the mud or a mixture of mud and bauxite at a higher temperature in caustic aluminate liquor to extract the majority of the remaining monohydrate and trihydrate, separating the supersaturated caustic aluminate liquor of higher Fe.sub.2 O.sub.3 content from the residue, precipitating alumina hydrate from the two supersaturated caustic aluminate liquors, recyling spent caustic aluminate liquor to digestion and calcining alumina hydrate to alumina with a Fe.sub.2 O.sub.3 content less than 0.03%.