Process for treating and recovering pickling waste liquids for stainless steel
US4565675A · kind A · utility
7Cited by
2References
2Claims
0Family size
Assignees
Inventors
Key dates
| Filing date | Mar 20, 1985 |
| Grant date | Jan 21, 1986 |
| Priority date | — |
| Expiry date | Mar 20, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S423/02
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A process for treating and recovering pickling waste liquids used for the pickling of stainless steel such as nitric-hydrofluoric acid, nitric acid, hydrochloric acid and, sulfuric acid is disclosed, which comprises recovering the nitric-hydrofluoric acid and the iron oxide or metallic ion from the waste liquids of nitric-hydrofluoric acid and nitric acid by two solvent extraction processes and recovering the Cr and Ni containing ferrite from the waste liquids of sulfuric acid or hydrochloric acid by a ferrite formation process. When the waste acid is sulfuric acid, gypsum of a high purity can be obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.