US3768988A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of pyritic sulfur from coal using solutions containing ferric ions
Assignee: Northrop Grumman Space and Mission Systems Corp
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Filing: 1971-07-19
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Granted: 1973-10-30
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Expires: 1991-07-19
Abstract
Abstract Finely divided coal or solid coal derivatives containing pyrite are reacted with a ferric ion solution; FeCl3 is particularly suitable. The ferric ion is reduced to ferrous ion and free sulfur is formed. The solution 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. At least 60 percent of the pyrite sulfur and pyrite iron is removed using the process of this invention. If desired, the ferrous chloride can be regenerated; this permits iron oxide to be recovered as a byproduct.
Inventors
- 👤 R Meyers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:30
CPC Classifications
C; C10; C10L; C10L9/00; C10L9/02
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
48 words
A process for reducing the pyritic sulfur content of coal which comprises reacting the coal with an effective amount of an aqueous solution containing Fe 3 ion selected from the class consisting of FeCl3 and ferric sulfate, and removing from the coal sulfur formed by the pyrite reaction.
Claim 2
Dependent Claim
72 words
A process for reducing the pyritic sulfur content of coal which comprises: reacting the coal with an effective amount of an aqueous solution containing Fe 3 ion; removing from the coal sulfur formed by the pyrite reaction using the following steps: separating the said solution from the treated coal; washing the coal and separating the wash solution from the treated coal; and drying the coal to volatize the free sulfur contained therein.
Claim 3
Dependent Claim
31 words
The process of claim 3 in which free sulfur from the volatization step is extracted with an organic solvent for sulfur selected from the class consisting of benzene, keRosene and p-cresol.
Claim 4
Dependent Claim
22 words
The process of claim 3 in which the aqueous solution employed is selected from the class consisting of FeCl3 and ferric sulfate.
Claim 5
Dependent Claim
28 words
The process of claim 3 in which the aqueous Fe 3 ion solution is selected from the class consisting of ferric acetate, ferric citrate and ferric ammonium sulfate.
Claim 6
Dependent Claim
85 words
A process for reducing a pyritic sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution containing Fe 3 ion and removing from the coal sulfur formed by the pyrite reaction using the following steps: separating the said solution from the treated coal; washing the coal and separating the wash solution from the coal; and extracting free sulfur from the treated coal with an organic solvent for sulfur selected from the class consisting of benzene, kerosene and p-cresol.
Claim 7
Dependent Claim
22 words
The process of claim 7 in which the aqueous solution employed is selected from the class consisting of FeCl3 and ferric sulfate.
Claim 8
Dependent Claim
28 words
The process of claim 7 in which the aqueous Fe 3 ion solution is selected from the class consisting of ferric acetate, ferric citrate and ferric ammonium sulfate.
Claim 9
Dependent Claim
80 words
A process for reducing the pyritic sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution of Fe 3 ion, and removing from the coal sulfur formed by the pyrite reaction using the following steps: separating the said solution from the treated coal; washing the coal and separating the wash solution from the treated coal; drying the coal to volatize the free sulfur contained therein; and oxidizing the separated solution to ferric ion.
Claim 10
Dependent Claim
25 words
The process of claim 10 in which the oxidizing step is carried out with a gas selected from the class consisting of air and oxygen.
Claim 11
Dependent Claim
22 words
The process of claim 10 in which the aqueous solution employed is selected from the class consisting of FeCl3 and ferric sulfate.
Claim 12
Dependent Claim
28 words
The process of claim 10 in which the aqueous Fe 3 ion solution is selected from the class consisting of ferric acetate, ferric citrate and ferric ammonium sulfate.
Claim 13
Dependent Claim
153 words
A process for reducing the pyritic sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution Fe 3 ion, and removing from the coal sulfur formed by the pyrite reaction employing the following steps: separating the said solution from the treated coal; washing the coal and separating the wash solution from the treated coal; drying the coal to volatize the free sulfur contained therein; extracting additional free sulfur from the treated coal with an organic solvent for sulfur selected from the class consisting of benzene, kerosene and p-cresol; concentrating the ferrous ion solution by evaporating some of the water; cooling the solution thereby precipitating ferrous ion; separating the ferrous ion precipitate from the solution containing ferric ion; oxidizing the ferrous ion precipitate to ferric ion and iron oxide; dissolving the ferric ion in water; and separating the iron oxide from the aqueous solution containing ferric ion.
Claim 14
Dependent Claim
22 words
The process of claim 14 in which the aqueous solution employed is selected from the class consisting of FeCl3 and ferric sulfate.
Claim 15
Dependent Claim
28 words
The process of claim 14 in which the aqueous Fe 3 ion solution is selected from the class consisting of ferric acetate, ferric citrate and ferric ammonium sulfate.
Claim 16
Dependent Claim
131 words
A process for reducing the pyritic sulfur content in coal which comprises: reacting the coal with an effective amount of an aqueous solution of Fe 3 ion and removing from the coal sulfur formed by the pyrite reaction using the following steps: separating the said solution from the treated coal; washing the coal and separating the wash solution from the treated coal; dRying the coal to volatize the free sulfur contained therein; concentrating ferrous ion solution by evaporating some of the water; cooling the solution therein by precipitating the ferrous ion; separating the ferrous ion precipitate from the solution containing ferric ion; air oxidizing the separated solution to ferric ion and iron oxide; dissolving the ferric ion in water; and separating the iron oxide from the aqueous solution containing ferric ion.
Claim 17
Dependent Claim
22 words
The process of claim 17 in which the aqueous solution employed is selected from the class consisting of FeCl3 and ferric sulfate.
Claim 18
Dependent Claim
28 words
The process of claim 17 in which the aqueous Fe 3 ion solution is selected from the class consisting of ferric acetate, ferric citrate and ferric ammonium sulfate.
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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) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |