Separation of heavy metals from waste water of the titanium dioxide industry
US5282977A · kind A · utility
8Cited by
5References
4Claims
0Family size
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Key dates
| Filing date | Sep 24, 1992 |
| Grant date | Feb 1, 1994 |
| Priority date | — |
| Expiry date | Sep 24, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/912
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
For economical and assured separation of chromium, vanadium and titanium ions from acidic waste waters, which accrue in great quantities in preparation of titanium dioxide, the pH is first raised to around a value of 3 by addition of dolomite brick powder. Directly thereafter, the pH is fine tuned into the range of 4.3 to 4.7 through addition of calcium hydroxide and/or sodium hydroxide, and the hydroxides are separated with the aid of a flocculating agent. Since iron ions and calcium ions remain mainly dissolved in the waste water through such selective precipitation, only a relatively small volume of slush has to be disposed of.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.