US4239736A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for increasing the brightness of limestone
Assignee: FRANKLIN INDUSTRIES Inc A CORP OF TE
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Filing: 1979-02-26
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Granted: 1980-12-16
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Expires: 1999-02-26
Abstract
Abstract Method for improving the brightness of limestone utilizing a flocculating agent and a bleaching agent where the pH of the slurry is between about 7 and 9.
Inventors
- 👤 Douglas H. Fenske
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:59
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/02; C09C1/021; C09C1/022; C01; C01P; C01P2004/00; C01P2004/51; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/60
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
71 words
A method for improving the brightness of limestone, containing at least a small amount of iron comprising grinding said limestone and forming a limestone slurry, adding an acidic flocculating agent to the slurry in amounts sufficient to provide a pH between about 7 and 9, adding a bleaching agent to the slurry in at least an amount sufficient to react with any iron present and separating the flocculate from the slurry.
Claim 2
Independent Claim
71 words
A method for improving the brightness of limestone, containing at least a small amount of iron comprising grinding said limestone and forming a limestone slurry, adding an acidic flocculating agent to the slurry in amounts sufficient to provide a pH between about 7 and 9, adding a bleaching agent to the slurry in at least an amount sufficient to react with any iron present and separating the flocculate from the slurry.
Claim 3
Dependent Claim
19 words
A method according to claim 1 in which the slurry has a solids content between about 15 and 50%.
Claim 4
Dependent Claim
24 words
A method according to claim 1 in which the flocculant is present in amounts between about 1 and 10 pounds per ton of limestone.
Claim 5
Dependent Claim
14 words
A method according to claim 1, in which the flocculating agent is acetic acid.
Claim 6
Dependent Claim
25 words
A method according to claim 1, in which the bleaching agent is present in amounts between about 3 and 15 pounds per ton of limestone.
Claim 7
Dependent Claim
14 words
A method according to claim 1, in which the bleaching agent is a hydrosulfite.
Claim 8
Dependent Claim
20 words
A method according to claim 1, in which the bleaching agent is added to the slurry in a non-oxidizing atmosphere.
Claim 9
Dependent Claim
21 words
A method according to claim 1, in which the slurry is maintained at a temperature between about 70° and 120° F.
Claim 10
Dependent Claim
21 words
A method according to claim 1, in which the limestone is ground to a sizing of less than about 20 microns.
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) | 1983-12-16 | 1984-06-16 | 1984-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-16 | 1988-06-16 | 1988-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-16 | 1992-06-16 | 1992-12-16 | $7700.00 | Window Closed / Lapsed |