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US3617562A
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Neutralization of ferrous iron-containing acid wastes
Assignee: EDWARD A MIHOK
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Filing: 1970-05-08
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Granted: 1971-11-02
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Expires: 1990-05-08
Abstract
Abstract Ferrous iron-containing acid waste waters are neutralized to form a dense, compact, and easily settleable sludge. Ferrous to ferric iron ratios are adjusted prior to neutralization by catalytic oxidation to conform approximately to that of magnetite; 1Fe to 2Fe . Neutralization of the acid waste and precipitation of a mixed valence iron oxide is accomplished using a finely divided limestone slurry as the preferred neutralizing agent.
Inventors
- 👤 Allen Cywin
- 👤 Edward A Mihok
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:04
CPC Classifications
C; C02; C02F; C02F9/00; C02F2101/00; C02F2101/10; C02F2101/20; Y; Y10; Y10S; Y10S423/00; Y10S423/01; Y10S423/02; Y10S423/09; Y10S423/15
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
37 words
The process of claim 1 wherein at least a part of the alkaline agent comprises limestone and wherein dissolved carbon dioxide is removed from the free-acid-neutralized waste stream without substantial further oxidation of the contained ferrous iron.
Claim 2
Dependent Claim
29 words
The process of claim 2 wherein carbon dioxide is removed by stripping the waste stream with an inert gas, said gas being substantially free of oxygen and carbon dioxide.
Claim 3
Dependent Claim
18 words
The process of claim 2 wherein carbon dioxide is removed by applying a vacuum to the waste stream.
Claim 4
Dependent Claim
27 words
The process of claim 2 wherein the ferrous to ferric iron ratio in the waste stream after oxidation is adjusted to a mole ratio of about 1:2.
Claim 5
Dependent Claim
22 words
The process of claim 5 wherein ferrous iron contained in the waste stream is oxidized in contact with a catalytically-active activated carbon.
Claim 6
Dependent Claim
25 words
The process of claim 6 wherein the activated carbon catalyst is conditioned prior to the oxidation step by contacting said carbon catalyst with acid solution.
Claim 7
Dependent Claim
75 words
The process of claim 7 wherein substantially all free acid is neutralized in a first stage using limestone as a neutralizing agent to produce an effluent having a pH in the rage of about 4 to about 6 and wherein the pH of said effluent is raised to a level in the range of about 7 to about 8 in a second state using a strong base as a neutralizing agent in said second stage.
Claim 8
Dependent Claim
11 words
The process of claim 8 wherein said strong base is lime.
Claim 9
Dependent Claim
26 words
The process of claim 7 wherein the limestone is in a very finely divided state; the median limestone particle diameter being less than about 10 microns.
Claim 10
Dependent Claim
15 words
The process of claim 10 wherein said finely divided limestone is produced by autogeneous grinding.
Claim 11
Dependent Claim
13 words
The process of claim 11 wherein the acid waste stream comprises pickle liquor.
Claim 12
Dependent Claim
37 words
The process of claim 12 wherein said pickle liquor is a temperature above about 150* F. and wherein carbon dioxide is removed from the limestone neutralization step by application of a vacuum to said neutralized waste stream.
Claim 13
Dependent Claim
35 words
The process of claim 13 wherein said applied vacuum removes sufficient dissolved carbon dioxide to raise the pH of the neutralized effluent to above about 7 thereby precipitating substantially all of the dissolved ferrous iron.
Claim 14
Dependent Claim
24 words
The process of claim 14 wherein an iron oxide precipitate having a composition approximating that of magnetite is Separated from the neutralized waste stream.
Claim 15
Dependent Claim
40 words
The process of claim 15 wherein said pickle liquor comprises hydrochloric acid pickle liquor, wherein said neutralized waste stream contains substantial amounts of calcium chloride and wherein hydrochloric acid is regenerated by treating said neutralized waste stream with sulfuric acid.
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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) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |