Process for eliminating heavy metals from phosphoric acid
US5279806A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 6, 1992 |
| Grant date | Jan 18, 1994 |
| Priority date | — |
| Expiry date | Jan 6, 2012 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/237
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Process for treating phosphoric acid for removing heavy metal cations, in particular cadmium, and sludges contained in the acid, characterized in that concentrated phosphoric acid having a low solids content is used and in that the calcium sulfate supersaturation of the phosphoric acid is controlled to form a compound of the formula I: EQU (SO.sub.4).sub.1-x (PO.sub.4).sub.x (H).sub.y Ca.sub.1-67 M; where x is between 0.5.times.10.sup.-2 and 1.times.10.sup.-1 ; y is between 0 and x+.delta.; .delta. indicates the chemical substitution of calcium by other metal cations; and M represents one or more metal cations contained in the initial phosphoric acid, whose total charge is approximately equal to 2.delta.+x-y. The following "Brief Description of Drawings" has been inserted between lines 19 and 20 on page 4 of the specification to comply with 37 CRF 1.74 and MPEP 608.01(f). The sole FIGURE of the Drawings is a flow diagram illustrating one embodiment of the process according to the present invention.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.