Patent US3794720A successfully refreshed from Google Patents.
US3794720A
Expired / Lapsed
US
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Process for producing hard ferrites
Assignee: Ferrox Iron Ltd
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Filing: 1972-03-31
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Granted: 1974-02-26
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Expires: 1992-03-31
Abstract
Abstract Barium, strontium or lead ferrite is produced in the usual manner by mixing together barium, strontium or lead carbonate and ferric oxide, calcining this to form the barium, strontium or lead ferrite and grinding the ferrite in slurry form in a mill to a particle size of about 1 micron average diameter. According to the invention, the barium, strontium or lead ferrite slurry before, during or after grinding in the mill has added thereto a reagent, which converts any barium, strontium or lead hydroxide present into a CO2-inactive form. This prevents the hydroxide from cementing the ferrite particles together into an irreversible cement-like mass during drying and storage in the dry form.
Inventors
- 👤 J Nye
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:43
CPC Classifications
C; C01; C01G; C01G49/00; C01G49/0018; C01G49/0036; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2683; C01P; C01P2004/00; C01P2004/20; C01P2004/60; C01P2004/61
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
15 words
A process according to claim 1 wherein the hydroxide is converted into an insoluble salt.
Claim 2
Dependent Claim
15 words
A process according to claim 1 wherein the hydroxide is converted into a soluble salt.
Claim 3
Dependent Claim
18 words
A process according to claim 2 wherein CO2 is passed into the slurry to form the insoluble salt.
Claim 4
Dependent Claim
19 words
A process according to claim 3 wherein acetic acid is added to the slurry to form the soluble salt.
Claim 5
Dependent Claim
25 words
A process according to claim 2 wherein the slurry has a surface active agent added thereto and the slurry containing surface active agent is dried.
Claim 6
Dependent Claim
21 words
A process according to claim 1 wherein the mechanically reduced slurry contains particles having an average diameter of about 1 micron.
Claim 7
Dependent Claim
17 words
A process according to claim 1 wherein the hydroxide is converted into the salt during mechanical reduction.
References Cited (Backward Citations)
US2502130A
Cited
US2904395A
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US3027327A
Cited
US3428416A
Cited
US3387918A
Cited
US3549315A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |