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US 12,371,337 B2Granted
Use of calcium fluoride in the bayer process
AssigneeRio Tinto Alcan International Limited
InventorsLisa Côté, Sébastien Fortin, Élizabeth Gingras-Lafleur
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Abstract
A Bayer process includes contacting bauxite and calcium fluoride with sodium hydroxide and forming a slurry, with the calcium fluoride may provide at least 1 wt. % of the calcium added to the process, and precipitating alumina from the slurry.
Claims21
A Bayer process that includes:
- contacting bauxite and calcium fluoride with sodium hydroxide and forming a slurry, with the calcium fluoride providing at least 1 wt. % of the calcium added to the process to precipitate phosphorus-containing compounds from the slurry, and
- precipitating alumina from a pregnant liquor of the slurry.
A Bayer process that includes:
- contacting bauxite and calcium fluoride with sodium hydroxide and forming a slurry, with the calcium fluoride providing at least 1 wt. % of the calcium added to the process,
- wherein the slurry includes an amount of calcium fluoride sufficient to precipitate a calcium-phosphorus-fluorine-containing compound and/or a calcium-phosphorus containing compound from a pregnant liquor of the slurry and thereby reducing the phosphorus concentration in the slurry, and precipitating alumina from the slurry pregnant liquor.
A Bayer process that includes:
- contacting boehmite-containing and/or gibbsite-containing bauxite and calcium fluoride with sodium hydroxide and forming a slurry, with the calcium fluoride providing at least 1 wt. % of the calcium added to the process to precipitate phosphorus-containing compounds from the slurry, and precipitating alumina from a pregnant liquor of the slurry.
A Bayer process that includes:
- contacting bauxite and calcium fluoride with sodium hydroxide and forming a slurry, with the calcium fluoride providing at least 1 wt. % of the calcium added to the process, and precipitating alumina from a pregnant liquor of the slurry;
- wherein the calcium added to the process includes
- low lime excess CaF2 containing 80-81% CaF2, 8-9% CaCO3, and 3-4% Ca(OH)2;
- or
- high lime excess CaF2 containing 64-65% CaF2, 5-6% CaCO3, and 17-18% Ca(OH)2.
2 more elements
Dependencies are inferred from the claim text.