Method and apparatus for treatment of fluorine-containing waste waters
US4028237A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1976 |
| Grant date | Jun 7, 1977 |
| Priority date | — |
| Expiry date | Mar 1, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/915
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
There are disclosed methods for removing fluorine values from fluorine-containing waste waters, in which aluminum ions are added to fluorine-containing waste water to convert fluorine to hydroxyfluoride complexes, adding phosphoric acid or phosphate and calcium compound are added to form fluoride apatite with residual fluorine in the waste water, and the hydroxy-fluoride complex and fluoride apatite are removed from the waste water. When waste water containing a phosphate in addition to fluorine is treated, the waste water is divided, according to the fluorine concentration, into concentrated waste water having a high fluorine concentration and dilute waste water having a low fluorine concentration; calcium compound is added to the concentrated waste water to form calcium fluoride, aluminum ions are added to the dilute waste water to form a hydroxy-fluoride complex; the so treated dilute waste water is mixed with the phosphate-containing concentrated waste water from which the precipitated calcium fluoride has been removed, calcium compound is added to the mixture to form fluoride apatite, and the hydroxy-fluoride complex and fluoride apatite are removed from the mixed waste water.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.