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US 5,041,269 AGranted
Recovery of alumina trihydrate in the Bayer process
AssigneeAllied Colloids Limited
InventorsGillian M. Moody, Christine A. Rushforth
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Abstract
In a Bayer process for production of aluminum, alumina trihydrate crystals are formed in the pregnant liquor and are flocculated using a combination of dextran and synthetic polymer, usually a homo- or copolymer of acrylic acid. The process is particularly advantageous where the liquor contains organic components such as humate and/or oxalate.
Claims21
A process for obtaining alumina trihydrate comprising steps of:
- digesting bauxite in an aqueous alkaline liquor to produce a slurry containing red mud solids and soluble aluminate in aqueous alkaline digesting liquor;
- separating the red mud solids and digesting liquor;
- washing the red mud solids to produce washed red mud solids and wash liquor;
- initiating precipitation of alumina trihydrate in the digesting liquor and optionally also the wash liquor;
- and
- flocculating the alumina trihydrate precipitate, wherein the flocculant comprises dextran and a water-soluble synthetic polymer formed from ethylenically unsaturated monomer including acrylic monomer.
3 more elements
Dependencies are inferred from the claim text.