US4002487A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for bleaching kaolin
Assignee: IMC Chemical Group Inc
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Filing: 1976-05-13
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Granted: 1977-01-11
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Expires: 1996-05-13
Abstract
Abstract In a process for treating raw kaolin clay to improve the color and brightness by treating the clay in an aqueous dispersion with sodium dithionite, the improvement consisting of treating the dispersion with hydroxylamine or salt thereof after the treatment with sodium dithionite is complete.
Inventors
- 👤 Robert F. Conley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:29
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/40; C09C1/42; C01; C01P; C01P2006/00; C01P2006/60
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
51 words
In a process for treating raw kaolin clay to improve the color and brightness by bleaching the clay in an aqueous dispersion with sodium dithionite, the improvement consisting of treating the dispersion with hydroxylamine or salt thereof within about 1 to 5 hours after the treatment with sodium dithionite is complete.
Claim 2
Dependent Claim
51 words
In a process for treating raw kaolin clay to improve the color and brightness by bleaching the clay in an aqueous dispersion with sodium dithionite, the improvement consisting of treating the dispersion with hydroxylamine or salt thereof within about 1 to 5 hours after the treatment with sodium dithionite is complete.
Claim 3
Dependent Claim
34 words
The improvement of claim 1 wherein the hydroxylamine is in the form of hydroxylammonium acid sulfate and is used in a proportion of from about 0.1 to about 2.0 lb per ton of clay.
Claim 4
Dependent Claim
18 words
The improvement of claim 2 wherein the hydroxylammonium acid sulfate is used at a pH below about 4.5.
Claim 5
Dependent Claim
24 words
The improvement of claim 3 wherein the hydroxylammonium sulfate is used in a proportion of about 0.5 to 1 lb per ton of clay.
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) | 1980-01-11 | 1980-07-12 | 1981-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-11 | 1984-07-12 | 1985-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-11 | 1988-07-12 | 1989-01-11 | $7700.00 | Window Closed / Lapsed |