Removal of P.sub.2 O.sub.5 from aluminum fluoride enriched crystallization mother liquors
US3965248A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1974 |
| Grant date | Jun 22, 1976 |
| Priority date | — |
| Expiry date | Aug 12, 1994 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01F7/50
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Aqueous AlF.sub.3 enriched crystallization mother liquors contaminated with P.sub.2 O.sub.5 values and having less than 5% free acidity are treated with a material which provides bismuth ions in the mother liquor in amounts small enough to insure that the Bi/PO.sub.4 mole ratio remains below about 1.05. Under these conditions, the bismuth and P.sub.2 O.sub.5 react essentially quantitatively to form a BiPO.sub.4 precipitate by which the P.sub.2 O.sub.5 can be separated from the mother liquor. Bismuth can be regenerated from the BiPO.sub.4 and recycled for further use in the process. The invention finds utility in the preparation of AlF.sub.3 by the reaction of an aluminum ore and P.sub.2 O.sub.5 contaminated HF or H.sub.2 SiF.sub.6 such as that available as a by-product of wet process phosphoric acid manufacture. The AlF.sub.3 reaction product is recovered by a crystallization step which, because it is normally only about 70 to 90% efficient, produces a mother liquor containing substantial amounts of AlF.sub.3. For economic reasons, this mother liquor is usually recycled to the process. However, the P.sub.2 O.sub.5 introduced with the HF or H.sub.2 SiF.sub.6 reactant appears in the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.