US4024232A
Expired / Lapsed
US
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Method of preparing magnetite having a controlled particle size, starting from ferrous sulphate solutions
Assignee: Montedison SpA
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Filing: 1975-02-24
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Granted: 1977-05-17
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Expires: 1995-02-24
Abstract
Abstract A method is disclosed for controlling the particle size of equiaxial magnetite obtained by a process for preparing same starting from ferrous sulphate solutions, characterized in that the reaction forming the magnetite is conducted in a suspension to which gamma FeO(OH) has been added in such an amount that Fe of the gamma FeO(OH) is 0.1-10% of the Fe<++> initially present in the solution.
Inventors
- 👤 Angelo Garberi
- 👤 Agostino Geddo
- 👤 Gian Lorenzo Marziano
- 👤 Bruno Viviani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:39
CPC Classifications
B; B82; B82Y; B82Y30/00; C; C09; C09C; C09C1/00; C09C1/22; C09C1/24; C01; C01G; C01G49/00; C01G49/02; C01G49/08; C01P; C01P2004/00; C01P2004/60; C01P2004/62; C01P2004/64; C01P2004/80; C01P2004/82; C01P2006/00; C01P2006/12; C01P2006/80
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
143 words
In a process for preparing equiaxial magnetite starting from a ferrous sulphate solution comprising a first step in which 2/3 of the Fe + + ion is precipitated as Fe(OH) 2 with an alkali at a temperature ranging from 15° to 40° C, said Fe(OH) 2 being oxidized to alpha-FeO(OH), and a second step, in which the remaining Fe + + is precipitated as Fe(OH) 2 with an alkali and the slurry is heated to a temperature ranging from 70° to 100° C, thus obtaining equiaxial magnetite; the improvement characterized in that in the aforesaid second step, before the heating of the slurry, gamma-FeO(OH) is added in such an amount that the Fe of the gamma-FeO(OH) is 0.1-10% of the Fe + + initially present in the solution, the higher the percentage of gamma-FeO(OH), the lower the average diameter of the resulting magnetite.
Claim 2
Dependent Claim
143 words
In a process for preparing equiaxial magnetite starting from a ferrous sulphate solution comprising a first step in which 2/3 of the Fe + + ion is precipitated as Fe(OH) 2 with an alkali at a temperature ranging from 15° to 40° C, said Fe(OH) 2 being oxidized to alpha-FeO(OH), and a second step, in which the remaining Fe + + is precipitated as Fe(OH) 2 with an alkali and the slurry is heated to a temperature ranging from 70° to 100° C, thus obtaining equiaxial magnetite; the improvement characterized in that in the aforesaid second step, before the heating of the slurry, gamma-FeO(OH) is added in such an amount that the Fe of the gamma-FeO(OH) is 0.1-10% of the Fe + + initially present in the solution, the higher the percentage of gamma-FeO(OH), the lower the average diameter of the resulting magnetite.
Claim 3
Dependent Claim
118 words
In a process for preparing equiaxial magnetite starting from a ferrous sulphate solution, in which, at a temperature ranging from 15° to 40° C, the Fe + + present in solution is precipitated with an alkali in the form of Fe(OH) 2 , then the slurry is heated to a temperature ranging from 70° to 100° C and the ferrous hydroxide is oxidized with air to magnetite; the improvement characterized in that after heating and before oxidation, gamma-FeO(OH) is added in such an amount that the Fe of the gamma-FeO(OH) is 0.1-10% of the Fe + + initially present in the solution, the higher the percentage of gamma FeO(OH), the lower the average diameter of the resulting magnetite.
Claim 4
Dependent Claim
118 words
In a process for preparing equiaxial magnetite starting from a ferrous sulphate solution, in which, at a temperature ranging from 15° to 40° C, the Fe + + present in solution is precipitated with an alkali in the form of Fe(OH) 2 , then the slurry is heated to a temperature ranging from 70° to 100° C and the ferrous hydroxide is oxidized with air to magnetite; the improvement characterized in that after heating and before oxidation, gamma-FeO(OH) is added in such an amount that the Fe of the gamma-FeO(OH) is 0.1-10% of the Fe + + initially present in the solution, the higher the percentage of gamma FeO(OH), the lower the average diameter of the resulting magnetite.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-16 | 1980-11-15 | 1981-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-16 | 1984-11-15 | 1985-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-16 | 1988-11-15 | 1989-05-17 | $7700.00 | Window Closed / Lapsed |