Process for removing boron from sulfuric acid
US4781909A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 1986 |
| Grant date | Nov 1, 1988 |
| Priority date | — |
| Expiry date | May 19, 2006 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B17/90
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Sulfuric acid contaminated with boron and fluoride values such as the waste acid of a boron trifluoride process is purified by contacting the contaminated acid with an inert gas to desorb boron trifluoride, and the inert gas is stripped by contacting with an absorbing liquid including concentrated sulfuric acid. Hydrogen fluoride and/or fluorosulfuric acid are added to contaminated sulfuric acid as agents to spring non-volatile boron value. In addition, the water content of the contaminated acid is adjusted within a narrow concentration range, to improve the efficiency of both the stripping and the absorption operations. The absorption of boron trifluoride into the absorbing sulfuric acid is improved when it contains boric acid. Preferably the contaminated sulfuric acid to be purified is one portion of the waste liquid and the absorbing liquid is another portion of the waste liquid of a boron trifluoride manufacturing process. Boric acid is added to the absorbing liquid, then boron trifluoride is stripped from the inert gas and absorbed into the absorbing liquid. The absorbing liquid along with stripped boron trifluoride is recycled to a boron trifluoride manufacturing process. The…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.