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US3764659A
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Process for the production of calcium hexacyanoferrate (ii)
Assignee: DEUTSCHE GOLD und SILBER SCHEIDEANSTALT DT
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Filing: 1970-11-02
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Granted: 1973-10-09
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Expires: 1990-11-02
Abstract
Abstract Calcium hexacyanoferrate-(II) is prepared by suspending 1 mole of calcium carbonate in an aqueous solution of 1 mole of ferrous salt and reacting at 30* - 90* C. with 2 moles of hydrogen cyanide at a pH of 2 - 5 and then adding an aqeous suspension of 2 moles of calcium hydroxide and 4 moles of hydrogen cyanide at 30* - 90* C. at a pH of at least 8.
Inventors
- 👤 H Reinhardt
- 👤 K Trebiner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:17
CPC Classifications
C; C01; C01C; C01C3/00; C01C3/08; C01C3/12
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
16 words
A process according to claim 1 wherein the hydrogen cyanide is added as liquid hydrocyanic acid.
Claim 2
Dependent Claim
17 words
A process according to claim 2 wherein the reaction is carried out at 60* to 70* C.
Claim 3
Dependent Claim
34 words
A process according to claim 3 wherein the first reaction step is carried out at a pH of 4 and the second reaction step is carried out at a pH of 8 to 12.
Claim 4
Dependent Claim
13 words
A process according to claim 4 wherein the ferrous salt is ferrous chloride.
Claim 5
Dependent Claim
20 words
A process according to claim 1 wherein the ferrous salt is in the form of ferrous salt containing waste acid.
Claim 6
Dependent Claim
13 words
A process according to claim 1 wherein the ferrous salt is ferrous chloride.
Claim 7
Dependent Claim
103 words
A process for the production of calcium hexacyanoferrate (II) comprising reacting 1 mole of calcium carbonate suspended in an aqueous solution of 1 mole of a ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate and ferrous nitrate at 30* to 90* C. with 2 moles of hydrogen cyanide at a pH of 2 to 5 with stirring, measuring In an aqueous suspension of 2 moles of calcium hydroxide and 4 moles of hydrogen cyanide with stirring at 30* to 90* C. in such manner that the pH does not go below 8 and recovering the calcium hexacyanoferrate (II) produced.
References Cited (Backward Citations)
US2113198A
Cited
DD144210A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |