US4132448A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of recovering coal in aqueous slurry form
Assignee: Chevron USA Inc
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Filing: 1977-09-06
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Granted: 1979-01-02
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Expires: 1997-09-06
Abstract
Abstract A method of in-situ coal recovery in slurry form from a coal deposit by first contacting the coal with a gaseous mixture of an oxygen-containing gas containing vaporized NO 2 , then with an aqueous alkaline solution to slurry the coal, and then recovering the slurried coal from the deposit.
Inventors
- 👤 Bruce W. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:46
CPC Classifications
E; E21; E21B; E21B43/00; E21B43/28
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
136 words
A method for recovering lignitic, sub-bituminous or bituminous coal in slurry form from a coal-containing formation comprising establishing a flow path from the earth's surface to a lignitic, sub-bituminous or bituminous coal-containing formation, flowing through said flow path a gaseous mixture containing up to 99 volume percent oxygen and at least about one volume percent NO 2 , up to an amount of NO 2 that will remain in vapor phase in said gaseous mixture, and contacting said coal-containing formation with said gaseous mixture to cause a reaction with the coal is said formation adjacent said flow path, flowing an aqueous alkaline solution through said flow path to contact the coal contained in said formation to break up and slurry the coal, and lifting the coal in slurry form from said formation to the earth's surface.
Claim 2
Independent Claim
136 words
A method for recovering lignitic, sub-bituminous or bituminous coal in slurry form from a coal-containing formation comprising establishing a flow path from the earth's surface to a lignitic, sub-bituminous or bituminous coal-containing formation, flowing through said flow path a gaseous mixture containing up to 99 volume percent oxygen and at least about one volume percent NO 2 , up to an amount of NO 2 that will remain in vapor phase in said gaseous mixture, and contacting said coal-containing formation with said gaseous mixture to cause a reaction with the coal is said formation adjacent said flow path, flowing an aqueous alkaline solution through said flow path to contact the coal contained in said formation to break up and slurry the coal, and lifting the coal in slurry form from said formation to the earth's surface.
Claim 3
Dependent Claim
23 words
The method of claim 1 further characterized in that the aqueous alkaline solution contains from 0.5% to 5.0% by weight NH 3 .
Claim 4
Dependent Claim
23 words
The method of claim 2 further characterized in that the aqueous NH 3 solution contains about 0.01% to 0.2% by weight of NaOH.
Claim 5
Dependent Claim
24 words
The method of claim 2 further characterized in that the aqueous NH 3 solution contains from about 0.014% to 0.28% by weight of KOH.
Claim 6
Dependent Claim
23 words
The method of claim 1 further characterized in that the oxygen content of the gaseous mixture is at least about 20% by volume.
Claim 7
Dependent Claim
27 words
The method of claim 1 further characterized in that an oxygen-containing gas alone is contacted with the coal prior to contacting the coal with said gaseous mixture.
Claim 8
Dependent Claim
11 words
The method of claim 6 wherein the oxygen-containing gas is air.
Claim 9
Dependent Claim
11 words
The method of claim 6 wherien the oxygen-containing gas is oxygen.
Claim 10
Dependent Claim
28 words
The method of claim 1 further characterized by sequentially repeating the steps of contacting coal with said gaseous mixture and contacting the coal with said aqueous alkaline solutions.
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) | 1982-01-01 | 1982-07-03 | 1983-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-01-01 | 1986-07-03 | 1987-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-01-01 | 1990-07-03 | 1991-01-02 | $7700.00 | Window Closed / Lapsed |