US3619137A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of iron oxide pigments
Assignee: Pfizer Pigments Inc
•
Filing: 1969-01-16
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Granted: 1971-11-09
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Expires: 1989-01-16
Abstract
Abstract Pigment-grade ferric oxide is precipitated from a solution of a ferrous salt by aerating at ambient temperature while introducing substantially two equivalents of base at such rate as to maintain the pH between 5 and 6.
Inventors
- 👤 Eric G Ratcliffe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:42
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/22; C09C1/24; C01; C01G; C01G49/00; C01G49/02; C01G49/06; C01P; C01P2004/00; C01P2004/01; C01P2004/03; Y; Y10; Y10S; Y10S423/00; Y10S423/01; Y10S423/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
16 words
The process of claim 1 wherein said temperature is between about 70* F. and 85* F.
Claim 2
Dependent Claim
13 words
The process of claim 1 wherein said pH is maintained below about 5.5.
Claim 3
Dependent Claim
22 words
The process of claim 1 where said alkaline reagent is a sodium, potassium, magnesium or lithium carbonate salt, or mixtures of these.
Claim 4
Dependent Claim
11 words
The process of claim 1 wherein said ferrous salt is copperas.
Claim 5
Dependent Claim
22 words
The process of claim 1 wherein said ferrous salt is present in a concentration of up to about 0.4 lb. per gallon.
Claim 6
Dependent Claim
16 words
The process of claim 6 wherein said concentration is at least about 0.2 lb. per gallon.
References Cited (Backward Citations)
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Cited
US1824936A
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US2388659A
Cited
US2696426A
Cited
US2822243A
Cited
US3539337A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-08 | 1975-05-10 | 1975-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-08 | 1979-05-10 | 1979-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-08 | 1983-05-10 | 1983-11-09 | $7700.00 | Window Closed / Lapsed |