US3901805A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removing toxic chromium from industrial effluents
Assignee: Badische Corp
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Filing: 1974-12-05
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Granted: 1975-08-26
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Expires: 1994-12-05
Abstract
Abstract A fluid reducing agent (e.g., sulfur dioxide) is injected into an essentially unimpeded stream of an acidified aqueous industrial effluent flowing in a simple conduit which is a mere passageway having no baffles or other obstructive or detaining means therein, the stream containing soluble chromium (VI) and having a turbulence characterized by a Reynolds Number of at least about 5,000. The resulting chromium (III) is then precipitated as Cr(OH)3, which is allowed to settle and is subsequently separated from the essentially chromium-free supernatant.
Inventors
- 👤 Ronald Stewart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:35
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/70; C02F2101/00; C02F2101/10; C02F2101/20; C02F2101/22
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
136 words
A PROCESS FOR REMOVING SOLUBLE CHROMIUM (VI) FROM AN AQUEOUS INDUSTRIAL EFFLUENT, WHICH PROCESS COMPRISES: A. INJECTING A FLUID ACID AND A FLUID REDUCING AGENT INTO AN ESSENTIALLY UNIMPEDED STREAM OF THE EFFLUENT FLOWING THROUGH A SIMPLE CONDUIT HAVING NO MIXING OR OBSTRUCTIVE MEANS LOCATED THEREIN, B. EFFECTING WITHIN THE ESSENTIALLY UNIMPEDED FLOWING STREAM OF ACIDIFIED EFFLUENT AND REDUCING AGENT IN THE CONDUIT A TURBULENT CONDITION CHARACTERIZED BY A REYNOLDS NUMBER OF AT LEAST ABOUT 5,000 C. PROVIDING A RESIDENCE TIME OF AT LEAST ABOUT 30 SECONDS FOR THE TURBULENT STREAM OF ACIDIFIED EFFLUENT AND REDUCING AGENT WITHIN THE CONDUIT, WHEREBY SUBSTANTIALLY COMPLETE REDUCTION OF CHROMIUM (VI) TO CHROMIUM (III) IS ACCOMPLISHED WITHIN THE CONDUIT, AND D. NEUTRALIZING THE EFFLUENT TO PRECIPITATE THE CHROMIUM (III) AS CR (OH)3 AND SEPARATING THE CHROMIUM-FREE SUPERNATANT FROM THE PRECIPITATE.
Claim 2
Dependent Claim
136 words
A PROCESS FOR REMOVING SOLUBLE CHROMIUM (VI) FROM AN AQUEOUS INDUSTRIAL EFFLUENT, WHICH PROCESS COMPRISES: A. INJECTING A FLUID ACID AND A FLUID REDUCING AGENT INTO AN ESSENTIALLY UNIMPEDED STREAM OF THE EFFLUENT FLOWING THROUGH A SIMPLE CONDUIT HAVING NO MIXING OR OBSTRUCTIVE MEANS LOCATED THEREIN, B. EFFECTING WITHIN THE ESSENTIALLY UNIMPEDED FLOWING STREAM OF ACIDIFIED EFFLUENT AND REDUCING AGENT IN THE CONDUIT A TURBULENT CONDITION CHARACTERIZED BY A REYNOLDS NUMBER OF AT LEAST ABOUT 5,000 C. PROVIDING A RESIDENCE TIME OF AT LEAST ABOUT 30 SECONDS FOR THE TURBULENT STREAM OF ACIDIFIED EFFLUENT AND REDUCING AGENT WITHIN THE CONDUIT, WHEREBY SUBSTANTIALLY COMPLETE REDUCTION OF CHROMIUM (VI) TO CHROMIUM (III) IS ACCOMPLISHED WITHIN THE CONDUIT, AND D. NEUTRALIZING THE EFFLUENT TO PRECIPITATE THE CHROMIUM (III) AS CR (OH)3 AND SEPARATING THE CHROMIUM-FREE SUPERNATANT FROM THE PRECIPITATE.
Claim 3
Dependent Claim
51 words
The process according to claim 1, wherein the fluid reducing agent is selected from the group consisting of: (a) sulfur dioxide; (b) an aqueous solution of a metallic sulfite; (c) an aqueous solution of a metallic hydrogen sulfite; (d) an aqueous solution of a ferrous salt; and (e) hydrogen sulfide gas.
Claim 4
Dependent Claim
37 words
The process according to claim 2, wherein the fluid reducing agent is sulfur dioxide and the acid content of the stream of effluent and reducing agent is controlled at a pH of between about 2 and 3.
Claim 5
Dependent Claim
22 words
The process according to claim 3, wherein the turbulent condition is characterized by a Reynolds Number of between about 5,000 and 40,000.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |