US3864453A
Expired / Lapsed
US
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Process for the production of alkali ferrocyanide
Assignee: Evonik Operations GmbH
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Filing: 1973-03-20
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Granted: 1975-02-04
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Expires: 1993-03-20
Abstract
Abstract Alkali ferrocyanides are prepared by converting calcium hexacyanoferrate (II) with an iron (II) salt to an iron (II) hexacyanoferrate (II), washing the complex with water until free of calcium ions and then reacting further with sodium, potassium or ammonium cyanide.
Inventors
- 👤 Helmut Reinhardt
- 👤 Karl Trebinger
- 👤 Gottfried Kallrath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:26
CPC Classifications
C; C01; C01C; C01C3/00; C01C3/08; C01C3/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
86 words
A PROCESS FOR THE PRODUCTION OF AN ALKALI OR AMMONIUM FERROCYANIDE COMPRISING (1) REACTING AT 10* TO 100*C. AN AQUEOUS SOLUTION OF CALCIUM HEXACYANOFERRATE (II) WITH AN AQUEOUS SOLUTION OF AN IRON (II) SALT, WASHING THE INSOLUBLE IRON (II) HEXACYANOFERRATE II COMPLEX FORMED WITH WATER UNTIL IT IS FREE OF CALCIUM IONS AND THEN (2) ADDING A AQUEOUS SOLUTION OF SODIUM, POTASSIUM OR AMMONIUM CYANIDE AT 20* TO 200*C. TO THE WASHED PRODUCT TO FORM AN AQUEOUS SOLUTION OF THE CORRESPONDING ALKALI OR AMMONIUM HEXACYANOFERRATE (II).
Claim 2
Dependent Claim
86 words
A PROCESS FOR THE PRODUCTION OF AN ALKALI OR AMMONIUM FERROCYANIDE COMPRISING (1) REACTING AT 10* TO 100*C. AN AQUEOUS SOLUTION OF CALCIUM HEXACYANOFERRATE (II) WITH AN AQUEOUS SOLUTION OF AN IRON (II) SALT, WASHING THE INSOLUBLE IRON (II) HEXACYANOFERRATE II COMPLEX FORMED WITH WATER UNTIL IT IS FREE OF CALCIUM IONS AND THEN (2) ADDING A AQUEOUS SOLUTION OF SODIUM, POTASSIUM OR AMMONIUM CYANIDE AT 20* TO 200*C. TO THE WASHED PRODUCT TO FORM AN AQUEOUS SOLUTION OF THE CORRESPONDING ALKALI OR AMMONIUM HEXACYANOFERRATE (II).
Claim 3
Dependent Claim
32 words
The process according to claim 1 comprising removing the water from the aqueous solution of the alkali or ammonium hexacyanoferrate (II) and recovering the alkali or ammonium hexacyanoferrate (II) in solid form.
Claim 4
Dependent Claim
21 words
The process according to claim 1 wherein a flocculating agent is added pH up to 8 prior to the water washing.
Claim 5
Dependent Claim
12 words
The process according to claim 3 wherein the flocculating agent is polyacrylamide.
Claim 6
Dependent Claim
30 words
The process according to claim 3 wherein the water soluble iron (II) salt is a nitrate or a halide wherein the halogen has an atomic weight of 35 to 127.
Claim 7
Dependent Claim
36 words
The process according to claim 1 wherein the aqueous calcium hexacyanoferrate (II) solution is an unfiltered solution which has been formed by the reaction of hydrogen cyanide, aqueous iron (II) salt solution and a calcium compound.
Claim 8
Dependent Claim
16 words
The process according to claim 1 wherein the iron (II) salt solution is a pickling solution.
Claim 9
Dependent Claim
19 words
The process according to claim 7 wherein the alkali cyanide solution is a waste solution from an electroplating operation.
Claim 10
Dependent Claim
19 words
The process according to claim 1 wherein the aqueous cyanide solution is a waste solution from an electroplating operation.
Claim 11
Dependent Claim
31 words
The process according to claim 1 wherein the iron (II) hexacyanoferrate is formed at 10* to 100*C. and the subsequent reaction with alkali or ammonium cyanide is carried out at 60*-95*C.
Claim 12
Dependent Claim
66 words
The process according to claim 1 wherein the iron (II) hexacyanoferrate (II) precipitate formed is washed by countercurrent flow with water, the precipitate in suspended condition goes downwardly and the water goes upwardly, the calcium salts are extracted from the precipitate by the wash water and the calcium ion free precipitate is recovered as a suspension, is concentrated and then reacted with the aqueouS cyanide solution.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |