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Patent US4289746A successfully refreshed from Google Patents.
US4289746A
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Process for preparation of micaceous iron oxide
Assignee: Central Glass Co Ltd
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Filing: 1980-05-19
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Granted: 1981-09-15
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Expires: 2000-05-19
Abstract
Abstract High purity hexagonal plate-like α-Fe 2 O 3 , commonly called micaceous iron oxide, is prepared by a hydrothermal treatment of either magnetite or an iron ore, or an iron oxide, of which principal component is magnetite together with an oxidizer in an aqueous alkali solution. Main advantage of this process is a great decrease in the consumption of alkali. Pure magnetite for use in this process can be prepared economically by a hydrothermal treatment of an iron ore, or an oxide, of which principal component is an oxide of trivalent iron in an aqueous alkali solution together with a compound of divalent iron and/or metallic iron.
Inventors
- 👤 Masanori Hayakawa
- 👤 Satoshi Nishimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:48
CPC Classifications
C; C01; C01G; C01G49/00; C01G49/02; C01G49/06; C01G49/08; C09; C09C; C09C1/00; C09C1/22; C09C1/24; C09C1/245; C01P; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/20; C01P2004/22; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/80
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
82 words
A process of preparing hexagonal plate-like crystals of α-Fe 2 O 3 , comprising mixing a first material of which a principal component thereof is magnetite, an aqueous alkali solution having an alkali concentration in the range of 1 to 20 N, and an oxidizer, in a closed vessel and hydrothermally treating the resultant mixture at a temperature of from about 100° to 400° C. for a time sufficient to effect formation of hexagonal plate-like crystals of α-Fe 2 O 3 .
Claim 2
Dependent Claim
82 words
A process of preparing hexagonal plate-like crystals of α-Fe 2 O 3 , comprising mixing a first material of which a principal component thereof is magnetite, an aqueous alkali solution having an alkali concentration in the range of 1 to 20 N, and an oxidizer, in a closed vessel and hydrothermally treating the resultant mixture at a temperature of from about 100° to 400° C. for a time sufficient to effect formation of hexagonal plate-like crystals of α-Fe 2 O 3 .
Claim 3
Dependent Claim
20 words
A process according to claim 1, wherein said aqueous alkali solution is an aqueous solution of an alkali metal hydroxide.
Claim 4
Dependent Claim
18 words
A process according to claim 2, wherein said concentration is in the range from 2 to 15 N.
Claim 5
Dependent Claim
26 words
A process according to claim 1, wherein said hydrothermal treatment is performed at a temperature in the range from about 120° C. to about 300° C.
Claim 6
Dependent Claim
20 words
A process according to claim 1, wherein said oxidizer is selected from the group consisting of chlorates, nitrates and perchlorates.
Claim 7
Dependent Claim
33 words
A process according to claim 5, wherein said oxidizer is sodium chlorate, the mole ratio of said oxidizer to magnetite contained in said first material is in the range from 0.16 to 0.8.
Claim 8
Dependent Claim
21 words
A process according to claim 1, wherein said oxidizer is selected from the group consisting of air, oxygen and hydrogen peroxide.
Claim 9
Dependent Claim
18 words
A process according to claim 1, wherein said first material is an iron ore in a pulverized state.
Claim 10
Dependent Claim
17 words
A process according to claim 1, wherein said first material is a ferrite in a pulverized state.
Claim 11
Dependent Claim
18 words
A process according to claim 1, wherein said first material is a mill scale in a pulverized state.
Claim 12
Dependent Claim
14 words
A process according to claim 1, wherein said first material consists essentially of magnetite.
Claim 13
Dependent Claim
51 words
A process according to claim 11, wherein said first material is prepared by subjecting powdery second material of which principal component is an oxide of trivalent iron to a hydrothermal treatment in an aqueous alkali solution at a temperature not lower than 90° C. together with a compound of divalent iron.
Claim 14
Dependent Claim
32 words
A process according to claim 12, wherein the mole ratio of said compound to said oxide of trivalent iron contained in said second material is in the range from 0.9 to 1.3.
Claim 15
Dependent Claim
27 words
A process according to claim 13, wherein said compound is selected from the group consisting of ferrous sulfate, ferrous chloride, ferrous nitrate, ferrous hydroxide and ferrous oxide.
Claim 16
Dependent Claim
50 words
A process according to claim 11, wherein said first material is prepared by subjecting a powdery second material of which principal component is an oxide of trivalent iron to a hydrothermal treatment in an aqueous alkali solution at a temperature not lower than 90° C. together with a metallic iron.
Claim 17
Dependent Claim
33 words
A process according to claim 15, wherein the mole ratio of said metallic iron to said oxide of trivalent iron contained in said second material is in the range from 0.2 to 0.5.
Claim 18
Dependent Claim
41 words
A process according to claims 12 or 15, wherein said aqueous alkali solution in the preparation of said first material is an aqueous solution of an alkali metal hydroxide and has a concentration in the range from 2 to 15 N.
Claim 19
Dependent Claim
37 words
A process according to claim 17, wherein said hydrothermal treatment in the preparation of said first material is performed in a closed vessel at a temperature in the range from about 120° C. to about 230° C.
Claim 20
Dependent Claim
14 words
A process according to claim 18, wherein said second material is an iron ore.
Claim 21
Dependent Claim
15 words
A process according to claim 18, wherein said second material is a red iron oxide.
Claim 22
Dependent Claim
13 words
A process according to claim 18, wherein said second material is γ-ferric oxide.
Claim 23
Dependent Claim
49 words
A process according to claim 11, wherein said first material is prepared by subjecting a powdery second material of which principal component is an oxide of trivalent iron to a hydrothermal treatment in an aqueous alkali solution together with a compound of a divalent iron and a metallic iron.
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) | 1984-09-14 | 1985-03-16 | 1985-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-14 | 1989-03-16 | 1989-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-14 | 1993-03-16 | 1993-09-15 | $7700.00 | Window Closed / Lapsed |