Method for recovery of cyanide from waste streams
US4708804A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 28, 1985 |
| Grant date | Nov 24, 1987 |
| Priority date | — |
| Expiry date | Jun 28, 2005 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC02F2101/18
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A process is provided for removing cyanide from a dilute cyanide solution. The solution is passed through a weak base anion exchange resin to absorb cyanide complexes. The resin is eluted with a weakly basic Ca(OH).sub.2 solution, to produce a cyanide-rich eluate. Elution is accomplished by recycling the eluting fluid past a bed of solid Ca(OH).sub.2, to maintain the eluting fluid in Ca(OH).sub.2 saturation. Recycling in this manner produces an eluate with relatively high cyanide concentration using economical reagents. The eluate is subjected to an acidification/volatilization process including acidification, preferably with H.sub.2 SO.sub.4, heating by introduction of steam and removal of volatilized HCN by an air sparge. The HCN-rich off-gas and slats produced therefrom may be recycled in the process. The cyanide-depleted waste streams may be disposed of in, for example, tailings ponds.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.