US4530768A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the disposal of waste water containing iron-cyanide complexes
Assignee: National Institute of Advanced Industrial Science and Technology
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Filing: 1984-02-06
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Granted: 1985-07-23
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Expires: 2004-02-06
Abstract
Abstract The invention provides an improvement in the disposal of a waste water coining iron-cyanide complexes including ferricyanides by the reduction of the ferricyanide ions into ferrocyanide in the presence of a zinc salt to precipitate the ferrocyanide ions in the form of zinc ferrocyanide. The improvement comprises the use of a sulfite, e.g. sodium sulfite, and a thiosulfate, e.g. sodium thiosulfate, in combination as the reducing agent whereby the reduction of the ferricyanide ions is complete within a relatively short time without being affected by the atmospheric oxygen or other factors.
Inventors
- 👤 Koichi Tanihara
- 👤 Keiko Tamai
- 👤 Seiji Yasuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:21
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/52; C02F1/5236; C02F1/5245; C02F2101/00; C02F2101/10; C02F2101/16; C02F2101/18; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/903; Y10S210/904
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
142 words
A method for removing iron-cyanide complexes from waste water containing iron-cyanide complexes including ferricyanides which comprises the steps of: (a) adjusting the content of zinc ions in the waste water so that the waste water contains at least 2 moles of zinc ions per mole of the ferricyanides; and (b) mixing with the waste water of sulfite selected from the group consisting of sulfites, hydrogen-sulfites and pyrosulfites of alkali metals and a thiosulfate selected from the group consisting of alkali metal thiosulfates and ammonium thiosulfate, in amounts sufficient to reduce the ferricyanides to ferrocyanides and in a molar proportion of the sulfite to the thiosulfate in the range from 1:10 to 6:1 at a pH effective to reduce and precipitate the iron cyanide complexes in the form of zinc ferrocyanide; and (c) removing the thus precipitated zinc ferrocyanide from the waste water.
Claim 2
Independent Claim
142 words
A method for removing iron-cyanide complexes from waste water containing iron-cyanide complexes including ferricyanides which comprises the steps of: (a) adjusting the content of zinc ions in the waste water so that the waste water contains at least 2 moles of zinc ions per mole of the ferricyanides; and (b) mixing with the waste water of sulfite selected from the group consisting of sulfites, hydrogen-sulfites and pyrosulfites of alkali metals and a thiosulfate selected from the group consisting of alkali metal thiosulfates and ammonium thiosulfate, in amounts sufficient to reduce the ferricyanides to ferrocyanides and in a molar proportion of the sulfite to the thiosulfate in the range from 1:10 to 6:1 at a pH effective to reduce and precipitate the iron cyanide complexes in the form of zinc ferrocyanide; and (c) removing the thus precipitated zinc ferrocyanide from the waste water.
Claim 3
Dependent Claim
26 words
The improvement as claimed in claim 1 wherein the thiosulfate is added to the waste water prior to or simultaneously with the addition of the sulfite.
Claim 4
Dependent Claim
32 words
The improvement as claimed in claim 1 wherein the reduction of the ferricyanides with the reducing agent is performed with concurrent blowing of oxygen or an oxygen-containing gas into the waste water.
Claim 5
Dependent Claim
31 words
The improvement as claimed in claim 1 wherein the molar of the sulfite to the total amount of the sulfite and the thiosulfate is in the range from 0.1 to 0.7.
Claim 6
Dependent Claim
17 words
The method of claim 1 further comprising adjusting the pH of the waste water to substantial neutrality.
Claim 7
Dependent Claim
18 words
The method of claim 1 wherein said step (a) comprises adding a zinc salt to the waste water.
Claim 8
Independent Claim
126 words
A method for removing iron-cyanide complexes from waste water containing iron-cyanide complexes including ferricyanides and at least 2 moles of of zinc ions per mole of ferricyanides, which comprises the steps of: (a) mixing with the waste water a sulfite selected from the group consisting of sulfites, hydrogen-sulfites and and pyrosulfites of alkali metals, and a thiosulfate selected from the group consisting of alkali metal thiosulfates and ammonium thiosulfates, in amounts sufficient to reduce the ferricyanides to ferrocyanides, and in a molar proportion of the sulfite to the thiosulfate in the range from 1:10 to 6:1 at a pH effective to reduce and precipitate the iron cyanide complexes in the form of zinc ferrocyanide; and (b) removing the thus precipitated zinc ferrocyanide from the waste water.
Claim 9
Independent Claim
126 words
A method for removing iron-cyanide complexes from waste water containing iron-cyanide complexes including ferricyanides and at least 2 moles of of zinc ions per mole of ferricyanides, which comprises the steps of: (a) mixing with the waste water a sulfite selected from the group consisting of sulfites, hydrogen-sulfites and and pyrosulfites of alkali metals, and a thiosulfate selected from the group consisting of alkali metal thiosulfates and ammonium thiosulfates, in amounts sufficient to reduce the ferricyanides to ferrocyanides, and in a molar proportion of the sulfite to the thiosulfate in the range from 1:10 to 6:1 at a pH effective to reduce and precipitate the iron cyanide complexes in the form of zinc ferrocyanide; and (b) removing the thus precipitated zinc ferrocyanide from the waste water.
Claim 10
Dependent Claim
17 words
The method of claim 7 further comprising adjusting the pH of the waste water to substantial neutrality.
Claim 11
Dependent Claim
23 words
The method of claim 7 further comprising adjusting the pH of the waste water so the waste water is at least slightly acidic.
Claim 12
Dependent Claim
24 words
The method of claim 7 wherein the thiosulfate is added to the waste water prior to or simultaneously with the addition of the sulfite.
Claim 13
Dependent Claim
31 words
The method of claim 7 wherein the reduction of the ferrycyanides with the reducing agent is performed with concurrent blowing of oxygen or an oxygen containing gas into the waste water.
Claim 14
Dependent Claim
30 words
The method of claim 7 wherein the molar ratio of the sulfite to the total amount of the sulfite and the thiosulfate is in the range from 0.1 to 0.7.
References Cited (Backward Citations)
US2039656A
Cited
US2112298A
Cited
US3505217A
Cited
US3736239A
Cited
JPS5428452A
Cited
JPS575598A
Cited
JPS5724690A
Cited
GB2091713A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-07-22 | 1989-01-21 | 1989-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-22 | 1993-01-21 | 1993-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-22 | 1997-01-21 | 1997-07-23 | $7700.00 | Window Closed / Lapsed |