US4144312A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Desulfurization of fluorite ores
Assignee: Individual
•
Filing: 1977-04-13
•
Granted: 1979-03-13
•
Expires: 1997-04-13
Abstract
Abstract Fluorite ores and concentrates commonly contain sulphur as an impurity usually as the sulphate. This sulphur can be largely removed by heating the ore or a concentrate under reducing conditions. In the preferred process the ore or a concentrate is pelletized with carbon, heated to a temperature up to 900° C. in a neutral atmosphere which is conveniently nitrogen or carbon dioxide or a mixture thereof.
Inventors
- 👤 Claude H. P. Lupis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 03:28
CPC Classifications
C; C01; C01F; C01F11/00; C01F11/20; C01F11/22; C01F11/02; C01F11/08
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
67 words
A method for reducing the sulphur content of fluorite ore or concentrate containing sulphur in the form of metal sulphates as an impurity which method comprises heating said fluorite ore or concentrate at temperatures between 700° and 1,000° C. under reducing conditions whereby said metal sulphates are transformed into metal oxides, and removing the sulphur in the form of gaseous compounds of sulphur via the effluent gases.
Claim 2
Independent Claim
67 words
A method for reducing the sulphur content of fluorite ore or concentrate containing sulphur in the form of metal sulphates as an impurity which method comprises heating said fluorite ore or concentrate at temperatures between 700° and 1,000° C. under reducing conditions whereby said metal sulphates are transformed into metal oxides, and removing the sulphur in the form of gaseous compounds of sulphur via the effluent gases.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein said temperatures are from 800° to 950° C.
Claim 4
Dependent Claim
33 words
The method of claim 1 wherein the reducing conditions are at least in part supplied by the presence of at least one selected from the class consisting of carbon, carbon monoxide and hydrogen.
Claim 5
Dependent Claim
21 words
The method of claim 1 wherein the reducing conditions are at least in part supplied by the presence of hydrogen gas.
Claim 6
Dependent Claim
20 words
The method of claim 1 wherein the reducing conditions are at least in part supplied by the presence of carbon.
Claim 7
Dependent Claim
16 words
The method of claim 5 wherein the carbon is in the form of graphite or coke.
Claim 8
Dependent Claim
18 words
The method of claim 5 including the prior step of forming pellets of ore or concentrate and carbon.
Claim 9
Dependent Claim
16 words
The method of claim 7 wherein said pellet contains up to 2.5% by weight of carbon.
Claim 10
Dependent Claim
17 words
The method of claim 7 wherein the pellet contains from 0.3 to 4% by weight of carbon.
Claim 11
Dependent Claim
14 words
The method of claim 7 wherein said pellets are dried prior to the heating.
Claim 12
Dependent Claim
19 words
The method of claim 7 wherein the temperature is sufficiently low that substantially no sintering between the pellets occurs.
Claim 13
Dependent Claim
34 words
The method of claim 5 wherein said temperatures are from 800° to 950° C., and wherein the ore or concentrate is maintained in a flow of gases consisting essentially of nitrogen and carbon dioxide.
Claim 14
Dependent Claim
13 words
The method of claim 1 wherein said temperatures are below about 940° C.
Claim 15
Dependent Claim
19 words
The method of claim 1 wherein the residence time at said temperatures is from 5 minutes to 1 hour.
Claim 16
Dependent Claim
20 words
The method of claim 1 wherein less than about 2% carbon monoxide and less than about 2% oxygen are present.
Claim 17
Dependent Claim
13 words
The method of claim 1 wherein SiO 2 is present in the fluorspar.
Claim 18
Dependent Claim
20 words
The method of claim 16 wherein Al 2 O 3 and P 2 O 5 is present in said fluorspar.
Claim 19
Dependent Claim
18 words
The method of claim 1 wherein said sulphur is present in particles of about 1 micron in size.
Claim 20
Dependent Claim
37 words
The method of claim 1 wherein said sulphate contains barium sulphate and said barium sulphate is transformed into barium oxide, and said sulphur is removed in the form of SO 2 or H 2 S or both.
Claim 21
Dependent Claim
16 words
The method of claim 1 wherein the temperature is sufficiently low that substantially no sintering occurs.
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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) | 1982-03-12 | 1982-09-11 | 1983-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-12 | 1986-09-11 | 1987-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-12 | 1990-09-11 | 1991-03-13 | $7700.00 | Window Closed / Lapsed |