Patent US4251504A successfully refreshed from Google Patents.
US4251504A
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Process for producing acicular goethite
Assignee: TDK Corp
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Filing: 1979-09-20
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Granted: 1981-02-17
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Expires: 1999-09-20
Abstract
Abstract An alkali hydroxide is added to an aqueous solution of ferrous salt to form a precipitate and a part of the solution is separated to control a ratio of an anion to a ferrous component to less than 1 and the ferrous component is oxidized to acicular goethite by bubbling air through the supernatant and precipitate.
Inventors
- 👤 Toshihiro Hamabata
- 👤 Shinji Umeki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:08
CPC Classifications
C; C01; C01G; C01G49/00; C01G49/02; C01G49/06; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70663; C01P; C01P2004/00; C01P2004/10; C01P2004/60; C01P2004/62; C01P2006/00; C01P2006/12; C01P2006/42
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
83 words
A process for producing an acicular goethite comprising: adjusting the pH of an aqueous solution of a ferrous salt to a value higher than 11; allowing a precipitate of ferrous hydroxide to form; adjusting the ratio of the anion of the ferrous salt to the ferrous hydroxide to 0.1 to 0.5 by separating a portion of the supernatant from said precipitate; and oxidizing the precipitate by bubbling an oxygen-containing gas through the remaining supernatant and precipitate at a temperature lower than 80° C.
Claim 2
Dependent Claim
83 words
A process for producing an acicular goethite comprising: adjusting the pH of an aqueous solution of a ferrous salt to a value higher than 11; allowing a precipitate of ferrous hydroxide to form; adjusting the ratio of the anion of the ferrous salt to the ferrous hydroxide to 0.1 to 0.5 by separating a portion of the supernatant from said precipitate; and oxidizing the precipitate by bubbling an oxygen-containing gas through the remaining supernatant and precipitate at a temperature lower than 80° C.
Claim 3
Dependent Claim
34 words
The process according to claim 1, wherein the pH of the aqueous solution of a ferrous salt is adjusted to a value higher than 11 by adding an alkali metal hydroxide or carbonate thereto.
Claim 4
Dependent Claim
28 words
The process according to claim 1, wherein the ferrous salt is selected from the group consisting of ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous phosphate and ferrous acetate.
Claim 5
Dependent Claim
24 words
The process according to claim 1, wherein the ratio of the anion of the ferrous salt to the ferrous hydroxide is 0.15 to 0.3.
Claim 6
Dependent Claim
23 words
The process according to claim 4, wherein the ratio of the anion of the ferrous salt to the ferrous hydroxide is about 0.17.
Claim 7
Dependent Claim
21 words
The process according to claim 1, wherein the temperature of the oxidation is in the range of 30° to 55° C.
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) | 1984-02-17 | 1984-08-18 | 1985-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-17 | 1988-08-18 | 1989-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-17 | 1992-08-18 | 1993-02-17 | $7700.00 | Window Closed / Lapsed |