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US4846978A
Expired / Lapsed
US
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Recovery of metals from solutions containing chelants
Assignee: Dow Chemical Co
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Filing: 1988-11-16
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Granted: 1989-07-11
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Expires: 2008-11-16
Abstract
Abstract Metal chelates in solution are decomposed more effectively and completely by ozonation when magnesium hydroxide is added to the chelate solution prior to ozonation. The process is particularly applicable to waste streams from which it is desired to recover metals to avoid contamination of the environment and/or reuse them.
Inventors
- 👤 David J. Leggett
- 👤 Joel G. Courtwright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:25
CPC Classifications
C; C02; C02F; C02F9/00; C02F1/00; C02F1/72; C02F1/78; C02F2101/00; C02F2101/10; C02F2101/20; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/911; Y10S210/912; Y10S210/913
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
62 words
In a process for decomposing metal chelates in an aqueous solution by ozonation in order to precipitate the metal therein, the improvement which comprises (a) adding magnesium hydroxide to said solution in an amount sufficient to increase the rate and/or quantity of metal precipitated upon subsequent ozonation and (b) contacting said solution containing magnesium hydroxide with ozone to decompose said metal chelates.
Claim 2
Dependent Claim
62 words
In a process for decomposing metal chelates in an aqueous solution by ozonation in order to precipitate the metal therein, the improvement which comprises (a) adding magnesium hydroxide to said solution in an amount sufficient to increase the rate and/or quantity of metal precipitated upon subsequent ozonation and (b) contacting said solution containing magnesium hydroxide with ozone to decompose said metal chelates.
Claim 3
Dependent Claim
31 words
The process of claim 1 wherein the amount of magnesium hydroxide added to the solution is from about 0.5 to 5.0 moles per mole of total metals present in the stream.
Claim 4
Dependent Claim
27 words
The process of claim 2 wherein the magnesium hydroxide added is from about 2 to about 3 moles per mole of total metals present in the stream.
Claim 5
Dependent Claim
22 words
The process of claim 1 wherein the temperature of the solution in step (b) is from about 5° to about 40° C.
Claim 6
Dependent Claim
16 words
The process of claim 1 wherein the ozonation of step (b) is conducted at ambient temperature.
Claim 7
Dependent Claim
36 words
The process of claim 1 wherein the metal chelates therein have been formed from metal ions and a chelant selected from the group consisting of nitrilotriacetic acid, iminodiacetic acid, alkylenepolyaminopolycarboxylic acids, citric acid and mixtures thereof.
Claim 8
Dependent Claim
13 words
The process of claim 6 wherein the alkylenepolyaminopolycarboxylic acid is an ethylene-polyaminopolycarboxylic acid.
Claim 9
Dependent Claim
12 words
The process of claim 7 wherein the ethylenepolyaminopolycarboxylic acid is ethylenediaminetetraacetic acid.
Claim 10
Dependent Claim
35 words
The process of claim 5 wherein the aqueous solution contains a mixture of metal chelates formed from at least one metal in ionic form and a mixture of chelants as complexing agents for the metal.
Claim 11
Dependent Claim
27 words
The process of claim 9 wherein the metal chelates are chelates of metals selected from the group consisting of copper, chromium, iron, zinc, barium and mixtures thereof.
Claim 12
Dependent Claim
14 words
The process of claim 1 wherein ultraviolet light is employed in the ozonation step.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-10 | 1993-01-09 | 1993-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-10 | 1997-01-09 | 1997-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-10 | 2001-01-09 | 2001-07-11 | $7700.00 | Window Closed / Lapsed |