US3832455A
Expired / Lapsed
US
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Preparation of zinc ferrite yellow pigments
Assignee: SMITH G LABOR
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Filing: 1972-10-25
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Granted: 1974-08-27
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Expires: 1992-10-25
Abstract
Abstract Preparation of so-called ''''tans'''' pigments, in the form of certain zinc ferrites of substantially nonmagnetic character, by, for example, aerating a mixture of an aqueous solution of ferrous sulfate with zinc oxide at a controlled pH and at somewhat elevated temperature, adding an alkali whereby to precipitate out hydrous ferric and zinc oxides, heating to effect coupling of said hydrous oxides, washing to effect removal of substantially all water-soluble salts which may be present, and then calcining at elevated temperatures.
Inventors
- 👤 G Smith
- 👤 K Orlandini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:12
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/22; C01; C01G; C01G49/00; C01G49/0018; C01G49/0063; C01P; C01P2006/00; C01P2006/12; C01P2006/13; C01P2006/60; C01P2006/80
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
44 words
The method of claim 1, in which the zinc compound is zinc oxide, the oxidation is effected by means of air, and in which at least substantially most of the oxidation is effected at a temperature in the range of about 120* to 125*F.
Claim 2
Dependent Claim
29 words
The method of claim 2, in which the weight ratio of the ferrous sulfate, calculated as Fe2O3, to the zinc oxide is about 67 Fe2O3 to 33 zinc oxide.
Claim 3
Dependent Claim
25 words
The method of claim 2, in which the alkaline material is a member selected from the group of caustic alkalies, ammonia and alkali metal carbonates.
Claim 4
Dependent Claim
17 words
The method of claim 2, in which the alkaline material is an aqueous solution of sodium carbonate.
Claim 5
Dependent Claim
22 words
The method of claim 2, in which the calcining is effected at a temperature in the range of about 1350* to 1800*F.
Claim 6
Independent Claim
173 words
A method of preparing yellowish zinc ferrite pigments having high temperature stability which comprises providing an aqueous slurry, at a temperature in the range of about 115* to about 130*F, containing an aqueous solution of ferrous sulfate and zinc oxide, the weight ratio of the ferrous sulfate, calculated as Fe2O3, to the zinc oxide being in the range of about 70-65 Fe2O3 to about 30 to 35 zinc oxide, aerating said slurry to effect oxidation of the ferrous iron to ferric iron while maintaining the reaction mixture at a pH in the range of about 5 to 6 by the addition of aqueous caustic alkali, then, when essentially all of the ferrous iron has been oxidized to ferric iron, adding aqueous caustic alkali to bring the pH to not in excess of about 8 and heating at a temperature of about 180* to 200*F to effect coupling of the hydrous zinc oxide with the ferric oxid4 hydrate, washing to effect removal of substantially all water-soluble salts which may be present, and then calcining.
Claim 7
Dependent Claim
52 words
The method of claim 7, in which at least substantially most of the oxidation is effected at a temperature in the range of about 120* to 125*F, and in which the weight ratio of the ferrous sulfate, calculated as Fe2O3, to the zinc oxide is about 67 Fe2O3 to 33 zinc oxide.
Claim 8
Dependent Claim
22 words
The method of claim 8, in which the calcining is effected at a temperature in the range of about 1350* to 1800*F.
Claim 9
Independent Claim
227 words
A method of preparing yellowish zinc ferrite pigments having high temperature stability which comprises admixing an aqueous slurry of zinc oxide with an aqueous ferrous sulfate solution in which the weight ratio of the ferrous sulfate, calculated as Fe2O3, to the zinc oxide, is in the range of about 70 to 65 Fe2O3 to 30-35 zinc oxide, said mixture being heated at a temperature of about 115* to about 130*F, aerating said reaction mixture to oxidize the ferrous iron to ferric iron while maintaining the pH of said reaction mixture in the range of about 5 to 6 by the periodic addition of an aqueous alkali metal carbonate solution, then, when the oxidation of the ferrous iron to ferric iron has at least mainly been completed, raising the temperature of the reaction mixture to about 140* to 160*F to essentially complete the oxidation of the ferrous iron to ferric iron while maintaining the pH in the range of about 5 to 6 by the addition of an aqueous alkali metal carbonate solution, then increasing the temperature of the reaction mixture up to about 200*F while maintaining the pH in the range of about 7 to 8 by the addition of an aqueous alkali metal carbonate solution, separating the solids from the reaction mixture, washing said solids to remove the water-soluble salts therefrom, and calcining said washed solids.
Claim 10
Dependent Claim
29 words
The method of claim 10, in which the weight ratio of the ferrous sulfate, calculated as Fe2O3, to the zinc oxide is about 67 Fe2O3 to 33 zinc oxide.
Claim 11
Dependent Claim
14 words
The method of claim 11, in which the alkali metal carbonate is sodium carbonate.
Claim 12
Dependent Claim
23 words
The methOd of claim 12, in which the calcining is effected at a temperature in the range of about 1350* to 1800* F.
Claim 13
Dependent Claim
200 words
In a method of preparing yellowish zinc ferrite pigments having high temperature stability, the steps which comprise admixing an aqueous slurry of zinc oxide with an aqueous iron sulfate solution, the weight ratio of the iron in said iron sulfate, calculated as Fe2O3, to the zinc oxide being about 70 to 65 Fe2O3 to 30 to 35 zinc oxide, the zinc oxide largely dissolving in said solution, adding an aqueous alkali metal carbonate solution to produce a pH in said solution of about 5 to 6, aerating said solution at a temperature in the range of about 115* to 125*F while maintaining the pH at about 6 to 6.5 by the addition of an aqueous alkali metal carbonate solution whereby to effect substantially complete oxidation of the ferrous iron to ferric iron, then, after completion of said aeration, increasing the pH by the addition of an aqueous alkali metal carbonate solution to produce a pH in the range of about 7 to 8 and heating the reaction mixture at a temperature in the range of about 180* to 200*F, separating the solids from the reaction mixture, washing said solids to remove the water-soluble salts therefrom, and calcining said washed solids.
Claim 14
Dependent Claim
30 words
The method of claim 14, in which the aqueous iron sulfate solution is one in which ferric and ferrous iron are present and in which the ferric iron largely predominates.
Claim 15
Dependent Claim
17 words
The method of claim 15, in which the aqueous alkaline material is a solution of sodium carbonate.
Claim 16
Dependent Claim
28 words
The method of claim 16, in which the weight ratio of the iron, calculated as Fe2O3, to the zinc oxide is about 67 Fe2O3 to 33 zinc oxide.
Claim 17
Dependent Claim
22 words
The method of claim 17, in which the calcining is effected at a temperature in the range of about 1350* to 1800*F.
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) | 1977-08-26 | 1978-02-25 | 1978-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-26 | 1982-02-25 | 1982-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-26 | 1986-02-25 | 1986-08-27 | $7700.00 | Window Closed / Lapsed |