US3926575A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of pyritic sulfur from coal
Assignee: Northrop Grumman Space and Mission Systems Corp
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Filing: 1971-07-19
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Granted: 1975-12-16
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Expires: 1991-07-19
Abstract
Abstract Finely divided coal or coal derivatives, containing pyrite, are reacted with sulfurous acid (the oxidizing agent); if desired, HCl may also be used to improve the reaction efficiency to remove pyritic sulfur from coal as shown by the following equations: Primary: Oxidation - reduction 4 FeS2 (pyrite) +3SO2 + 12 HCl -> 4 FeCl3 + 11S + 6 H2O Secondary: Oxidation - reduction 4 FeCl3 + FeS2 (Pyrite) -> 6 FeCl2 + 4S Overall reaction 6 FeS2 + 3SO2 + 12 HCl -> 6 FeCl2 + 15S + 6 H2O The solution containing ferrous chloride and unreacted sulfurous acid is then filtered from the coal which is then washed and heat dried under low pressure. Most of the free sulfur is volatized from the coal due to the heat drying; additional free sulfur can be removed by additional washing and heat drying and/or solvent extraction techniques. If desired, the ferrous chloride can be oxidized to ferric oxide and hydrochloric acid. The hydrochloric acid may be recycled and the iron oxide used for production of steel or discarded.
Inventors
- 👤 Robert A Meyers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:47
CPC Classifications
C; C10; C10L; C10L9/00; C10L9/02
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
61 words
A PROCESS FOR REDUCING THE PYRITE SULFUR CONTENT IN COAL WHICH COMPRISES: REACTING THE TOTAL CONTAINING FES2 WITH AN EFFECTIVE AMOUNT OF AN AQUEOUS SOLUTION OF SULFUROUS ACID AT ABOUT 100*C TO 140*C AND HYDROCHLORIC ACID TO FORM FREE SULFUR IN THE COAL MATRIX, FILTERING THE SOLUTION FROM THE COAL; WASHING THE COAL; AND REMOVING THE FREE SULFUR FROM THE COAL.
Claim 2
Dependent Claim
61 words
A PROCESS FOR REDUCING THE PYRITE SULFUR CONTENT IN COAL WHICH COMPRISES: REACTING THE TOTAL CONTAINING FES2 WITH AN EFFECTIVE AMOUNT OF AN AQUEOUS SOLUTION OF SULFUROUS ACID AT ABOUT 100*C TO 140*C AND HYDROCHLORIC ACID TO FORM FREE SULFUR IN THE COAL MATRIX, FILTERING THE SOLUTION FROM THE COAL; WASHING THE COAL; AND REMOVING THE FREE SULFUR FROM THE COAL.
Claim 3
Dependent Claim
67 words
A process for reducing the pyrite sulfur content in coal which comprises: reacting the coal containing FeS2 with an effective amount of an aqueous solution of sulfurous acid and hydrochloric acid at about 100*C to 140*C to form free sulfur in the coal matrix; filtering the solution from the coal; washing the coal; and extracting the free sulfur from the coal with an organic solvent for sulfur.
Claim 4
Dependent Claim
67 words
A process for reducing the pyrite sulfur content in coal which comprises: reacting the coal containing FeS2 with an effective amount of an aqueous solution of sulfurous acid and hydrochloric acid at about 100*C to 140*C to form free sulfur in the coal matrix; filtering the solution from the coal; washing the coal; and extracting the free sulfur from the coal with an organic solvent for sulfur.
Claim 5
Dependent Claim
23 words
The process of claim 2 in which the sulfur solvent is selected from the class consisting of benzene, kerosene, gas oil, and paracresol.
Claim 6
Dependent Claim
17 words
The process of claim 2 in which the extraction temperature varies from 50*C up to solvent reflux.
Claim 7
Dependent Claim
62 words
A process for reducing the pyrite sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution of sulfurous acid and hydrochloric acid at about 100*C to 140*C to form free sulfur in the coal matrix; filtering the solution from the coal; washing the coal; and heat drying the coal to volatize the free sulfur therein.
Claim 8
Dependent Claim
62 words
A process for reducing the pyrite sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution of sulfurous acid and hydrochloric acid at about 100*C to 140*C to form free sulfur in the coal matrix; filtering the solution from the coal; washing the coal; and heat drying the coal to volatize the free sulfur therein.
Claim 9
Dependent Claim
71 words
A process for reducing the pyrite sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution of sulfurous acid and hydrochloric acid to form free sulfur in the coal matrix; filtering the solution from the coal; washing the coal; extracting the free sulfur from the coal with an organic solvent for sulfur and heat drying the coal to remove the free sulfur contained therein.
Claim 10
Dependent Claim
71 words
A process for reducing the pyrite sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution of sulfurous acid and hydrochloric acid to form free sulfur in the coal matrix; filtering the solution from the coal; washing the coal; extracting the free sulfur from the coal with an organic solvent for sulfur and heat drying the coal to remove the free sulfur contained therein.
References Cited (Backward Citations)
US2057486A
Cited
US2739105A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |