Purification of boron-containing sulfuric acid
US4265871A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 7, 1979 |
| Grant date | May 5, 1981 |
| Priority date | — |
| Expiry date | May 7, 1999 |
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. Fluosulfonic acid is added to contaminated sulfuric acid at levels approximately three times the molar values of boric acid contaminant as an agent to spring non-volatile boron values. 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 inert gas can be recycled to the desorbing step.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.