Production of rare earth hydroxides from phosphate ores
US4758412A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 10, 1986 |
| Grant date | Jul 19, 1988 |
| Priority date | — |
| Expiry date | Nov 10, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P10/20
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The rare earth hydroxides are improvedly prepared by (i) treating a rare earth phosphate mineral, e.g., monazite or xenotime, with an aqueous solution of an alkali metal hydroxide, (ii) separating therefrom rare earth hydroxide solids and a liquid phase essentially consisting of alkali metal phosphate and alkali metal hydroxide, (iii) crystallizing alkali metal phosphate from said liquid phase, (iv) separating the mother liquor of crystallization therefrom which contains said alkali metal hydroxide, (v) adding calcium oxide or hydroxide to the mother liquor thus separated to form a precipitate therein, (vi) separating said formed precipitate, and (vii) recycling the mother liquor of separation to said treatment step (i).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.