Patent US4024232A successfully refreshed from Google Patents.
US4024232A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing magnetite having a controlled particle size, starting from ferrous sulphate solutions
Assignee: Montedison SpA
•
Filing: 1975-02-24
•
Granted: 1977-05-17
•
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 18:55
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)
US1392927A
Cited
GB433333A
Cited
US2939767A
Cited
GB1133863A
Cited
US3617562A
Cited
US3755554A
Cited
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 |