Production of phosphoric acid and additional products from phosphate ore
US4479923A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 6, 1983 |
| Grant date | Oct 30, 1984 |
| Priority date | — |
| Expiry date | Jul 6, 2003 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/322
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Phosphate rock, including low grade phosphate ore, is treated to recover phosphoric acid and other valuable products by a series of steps including contacting phosphate ore with a weak phosphoric acid to form a suspension of at least a portion of the slimes contained in the ore so that the slimes can be separated from the ore, and separating the slimes to provide a deslimed phosphate ore. Deslimed phosphate rock is solubilized with phosphoric acid to convert at least a portion of the calcium contained in the rock and form a solution of monocalcium phosphate and phosphoric acid. After removal of solids, this solution can be treated with sulfuric acid in a gypsum crystallizer to form gypsum and the phosphoric acid product wherein filterable gypsum crystals are obtained by maintaining a total SO.sub.3 content of 1.5-4 wt. % in a first crystallizer and neutralizing the SO.sub.3 in a second crystallizer. In other aspects of the invention, at least a portion of the phosphoric acid produced may be recycled to convert additional ore and the slime suspension may be treated to recover the weak acid recovered from the suspension. Further, wash water from the gypsum filter may be recycled to t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.