US3887684A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of sulfur dioxide from waste gases
Assignee: Manufacturers Hanover Trust Co
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Filing: 1973-09-28
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Granted: 1975-06-03
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Expires: 1993-09-28
Abstract
Abstract In a process for removing sulfur dioxide from dilute sulfur dioxide gases, the gases are brought into contact with an aqueous solution of zinc sulfate which absorbs the sulfur dioxide, and the absorption products are then partially or fully removed. The aqueous solution may then be recirculated into contact with additional waste gases to produce a cyclic process.
Inventors
- 👤 Frank S Griffith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:19
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/507; B01D53/14; B01D53/1493; C; C01; C01B; C01B17/00; C01B17/48; C01B17/50; C01B17/60
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
87 words
A PROCESS FOR RECOVERING SULFUR DIOXIDE FROM DILUTE SULFUR DIOXIDE GASES, COMPRISING: A. CONTACTING SAID GASES WITH AN AQUEOUS SOLUTION OF ZINC SULFATE IN WHICH THE CONCENTRATION OF ZINC IN AND THE PH OF, THE AQUEOUS SOLUTION OF ZINC SULFATE IS MAINTAINED, BY THE ADDITION OF A ZINC OXIDE CONTAINING MATERIAL, AT LEVELS SUFFICIENT TO PRODUCE A ZINC SULFITE-ZINC SULFATE PRECIPITATE, AND B. ABSORBING SULFUR DIOXIDE FROM SAID GASES IN SAID AQUEOUS SOLUTION OF ZINC SULFATE, C. REMOVING SAID PRECIPITATE FROM SAID AQUEOUS SOLUTION OF ZINC SULFATE.
Claim 2
Dependent Claim
87 words
A PROCESS FOR RECOVERING SULFUR DIOXIDE FROM DILUTE SULFUR DIOXIDE GASES, COMPRISING: A. CONTACTING SAID GASES WITH AN AQUEOUS SOLUTION OF ZINC SULFATE IN WHICH THE CONCENTRATION OF ZINC IN AND THE PH OF, THE AQUEOUS SOLUTION OF ZINC SULFATE IS MAINTAINED, BY THE ADDITION OF A ZINC OXIDE CONTAINING MATERIAL, AT LEVELS SUFFICIENT TO PRODUCE A ZINC SULFITE-ZINC SULFATE PRECIPITATE, AND B. ABSORBING SULFUR DIOXIDE FROM SAID GASES IN SAID AQUEOUS SOLUTION OF ZINC SULFATE, C. REMOVING SAID PRECIPITATE FROM SAID AQUEOUS SOLUTION OF ZINC SULFATE.
Claim 3
Dependent Claim
87 words
A process for recovering sulfur dioxide from dilute sulfur dioxide gases, comprising: a. contacting said gases with an aqueous solution of zinc sulfate in which the concentration of zinc in and the pH of, the aqueous solution of zinc sulfate is maintained, by the addition of a zinc oxide containing material, at levels sufficient to produce a zinc sulfite-zinc sulfate precipitate, and b. absorbing sulfur dioxide from said gases in said aqueous solution of zinc sulfate, c. removing said precipitate from said aqueous solution of zinc sulfate.
Claim 4
Dependent Claim
87 words
A process for recovering sulfur dioxide from dilute sulfur dioxide gases, comprising: a. contacting said gases with an aqueous solution of zinc sulfate in which the concentration of zinc in and the pH of, the aqueous solution of zinc sulfate is maintained, by the addition of a zinc oxide containing material, at levels sufficient to produce a zinc sulfite-zinc sulfate precipitate, and b. absorbing sulfur dioxide from said gases in said aqueous solution of zinc sulfate, c. removing said precipitate from said aqueous solution of zinc sulfate.
Claim 5
Dependent Claim
27 words
A process as defined in claim 1 wherein the concentration of zinc in the aqueous solution of zinc sulfate is maintained above about 2 percent by weight.
Claim 6
Dependent Claim
22 words
A process as defined in claim 1 wherein the pH of the aqueous solution of zinc sulfate is maintained above about 4.
Claim 7
Dependent Claim
23 words
A process as defined in claim 1 wherein the pH of the aqueous zinc sulfate solution is maintained by addition of zinc oxide.
Claim 8
Dependent Claim
25 words
A process as defined in claim 1 wherein the temperature of the aqueous zinc sulfate solution is maintained between normal room temperature and about 70*C.
Claim 9
Dependent Claim
33 words
A process as defined in claim 1 wherein the zinc sulfite-zinc sulfate precipitate is removed and heated to a temperature sufficient to effect decomposition of same into zinc oxide and oxides of sulfur.
Claim 10
Dependent Claim
31 words
A process as defined in claim 1 wherein the aqueous zinc sulfate solution, after removal of the zinc sulfite-zinc sulfate precipitate, is returned to contact with additional dilute sulfur dioxide gases.
Claim 11
Dependent Claim
38 words
A process as defined in claim 1 wherein at least a portion of the aqueous solution of zinc sulfate is removed after contact with the dilute sulfur dioxide gases for production of commercial zinc sulfate or hydrate thereof.
Claim 12
Dependent Claim
93 words
A process for recovering sulfur dioxide from dilute sulfur dioxide gases, comprising: a. contacting said gases with an aqueous solution of zinc sulfate, in which the concentration of zinc in the aqueous solution of zinc sulfate is maintained above about 2 percent by weight and the pH of said aqueous solution is maintained above about 4 by addition of zinc oxide, b. absorBing sulfur dioxide from said gases in said aqueous solution of zinc sulfate, and c. removing at least a portion of the absorption products from said aqueous solution of zinc sulfate.
Claim 13
Dependent Claim
93 words
A process for recovering sulfur dioxide from dilute sulfur dioxide gases, comprising: a. contacting said gases with an aqueous solution of zinc sulfate, in which the concentration of zinc in the aqueous solution of zinc sulfate is maintained above about 2 percent by weight and the pH of said aqueous solution is maintained above about 4 by addition of zinc oxide, b. absorBing sulfur dioxide from said gases in said aqueous solution of zinc sulfate, and c. removing at least a portion of the absorption products from said aqueous solution of zinc sulfate.
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) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |