US3617560A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Limestone neutralization of dilute acid waste waters
Assignee: United States Department of the Interior
•
Filing: 1969-09-17
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Granted: 1971-11-02
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Expires: 1989-09-17
Abstract
Abstract Dilute acid wastes, such as mine drainage waters, are neutralized by reaction with an extremely finely divided limestone slurry after which the neutralized effluent is aerated to strip carbon dioxide and oxidize ferrous iron. After clarification, the product stream is suitable for disposal in surface waters.
Inventors
- 👤 Maurice Deul
- 👤 Edward A Mihok
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:53
CPC Classifications
C; C02; C02F; C02F9/00; C02F1/00; C02F1/52; C02F1/529; C02F1/58; C02F1/62; C02F1/64; C02F1/645; C02F1/66; C02F2101/00; C02F2101/10; C02F2101/20; C02F2101/203; C02F2103/00; C02F2103/10; C02F2209/00; C02F2209/06; Y; Y10; Y10S; Y10S423/00; Y10S423/01; Y10S423/02; Y10S423/09; Y10S423/15
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
19 words
The process of claim 1 wherein the waste acid stream comprises a mineral acid and also contains dissolved metals.
Claim 2
Dependent Claim
31 words
The process of claim 2 wherein the mineral acid is sulfuric acid, wherein the dissolved metal comprises iron, and wherein at least part of said iron is in the ferrous state.
Claim 3
Dependent Claim
25 words
The process of claim 3 wherein the aeration is continued for a sufficient time to substantially completely oxidize the ferrous iron to the ferric state.
Claim 4
Dependent Claim
15 words
The process of claim 3 wherein the particulate limestone slurry is produced by autogenous grinding.
Claim 5
Dependent Claim
41 words
The process of claim 5 wherein the waste acid stream is divided into a major portion and a minor portion; the minor portion being passed through the rotating mill at a rate which maximizes the production of extremely fine limestone particles.
Claim 6
Dependent Claim
20 words
The process of claim 6 which precipitated gypsum and iron oxide is removed form the aeration product stream by settling.
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) | 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 |