Patent US1882476A successfully refreshed from Google Patents.
Patent US4402759A successfully refreshed from Google Patents.
US4402759A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for inhibiting the corrosion of a metal installation in contact with an acid bath
Assignee: Solvay SA
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Filing: 1980-09-04
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Granted: 1983-09-06
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Expires: 2000-09-04
Abstract
Abstract The invention relates to a process for inhibiting the corrosion of an installation, made of a material chosen from amongst the metals which are less noble than hydrogen, and their alloys, in contact with an acid bath containing an alkylpyridinium chloride. A soluble cyanide complex, which is capable of forming an insoluble compound by reacting with ferric ions in the bath, is added to the bath so as to limit the concentration of the ferric ions in the bath to a maximum of 30 mg/kg. The content of ferric ions in the bath is controlled by means of a potentiometric measurement so as to bring the potential of the bath into the region of a predetermined value. The invention applies in particular to the treatment of baths for cleaning or descaling steel installations.
Inventors
- 👤 Daniel Tytgat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:49
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/04; C23G; C23G1/00; C23G1/02; C23G1/04
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
165 words
Process for inhibiting the corrosion, of an installation in contact with an aqueous bath containing a mineral acid and an alkylpyridinium chloride, the installation being made of a metal which is less noble than hydrogen in the bath or of an alloy containing a metal of this type, wherein ferric ions are formed in the bath, comprising: treating the installation by adding to the bath a soluble cyanide complex, which is capable of forming an insoluble compound by reacting with ferric ions in the bath, measuring the concentration of ferric ions in the bath, and adjusting the amount of said soluble cyanide complex added to the bath during the treating so as to permanently keep, in the bath in contact with the installation, a concentration of ferric ions between 30 mg/kg and a zero concentration, and that with a zero concentration the adjusted amount of the soluble cyanide complex added is that which is strictly necessary to obtain a zero concentration of ferric ions therein.
Claim 2
Dependent Claim
165 words
Process for inhibiting the corrosion, of an installation in contact with an aqueous bath containing a mineral acid and an alkylpyridinium chloride, the installation being made of a metal which is less noble than hydrogen in the bath or of an alloy containing a metal of this type, wherein ferric ions are formed in the bath, comprising: treating the installation by adding to the bath a soluble cyanide complex, which is capable of forming an insoluble compound by reacting with ferric ions in the bath, measuring the concentration of ferric ions in the bath, and adjusting the amount of said soluble cyanide complex added to the bath during the treating so as to permanently keep, in the bath in contact with the installation, a concentration of ferric ions between 30 mg/kg and a zero concentration, and that with a zero concentration the adjusted amount of the soluble cyanide complex added is that which is strictly necessary to obtain a zero concentration of ferric ions therein.
Claim 3
Dependent Claim
13 words
Process according to claim 1, wherein the soluble cyanide complex used is tetravalent.
Claim 4
Dependent Claim
14 words
Process according to claim 2, wherein ferrocyanide is used as the soluble cyanide complex.
Claim 5
Dependent Claim
20 words
Process according to claim 3, wherein the ferrocyanide complex is added to the bath in the form of potassium ferrocyanide.
Claim 6
Dependent Claim
40 words
Process according to any one of claims 1 to 4, wherein the amount of soluble cyanide complex added to the bath is adjusted so as to keep the concentration of ferric ions in the bath between 5 and 1 mg/kg.
Claim 7
Dependent Claim
36 words
Process according to any one of claims 1 to 4, wherein the amount of soluble cyanide complex added to the bath is adjusted by measuring the potential of the material of which the installation is made.
Claim 8
Dependent Claim
19 words
Process according to any one of claims 1 to 4, wherein hydrochloric acid is used as the mineral acid.
Claim 9
Dependent Claim
27 words
Process according to claim 7, wherein a normal solution of hydrochloric acid containing from 75 to 200 mg of an alkylpyridinium chloride is used as the bath.
Claim 10
Dependent Claim
29 words
Process according to any one of claims 1 to 4, wherein the alkylpyridinium chloride is chosen from amongst those derived from alkanes possessing from 10 to 18 carbon atoms.
Claim 11
Dependent Claim
27 words
Process according to any one of claims 1 to 4, wherein the installation is made of chromium, zinc, iron, cobalt, nickel or an alloy of these metals.
Claim 12
Dependent Claim
119 words
In a process for treating an installation made of metal which is less noble than hydrogen or of an alloy containing a metal of this type, by contacting the installation with an aqueous bath containing a mineral acid and alkylpyridinium chloride, wherein ferric ions are formed in the bath, the improvement comprising: adding to the bath a soluble cyanide complex which is capable of forming an insoluble compound by reacting with ferric ions in the bath, measuring the concentration of ferric ions in the bath, and adjusting the amount of said soluble cyanide complex added to the bath during the treating in order to keep the amount of ferric ions in the bath permanently between 0.1 and 30 mg/kg.
Claim 13
Dependent Claim
119 words
In a process for treating an installation made of metal which is less noble than hydrogen or of an alloy containing a metal of this type, by contacting the installation with an aqueous bath containing a mineral acid and alkylpyridinium chloride, wherein ferric ions are formed in the bath, the improvement comprising: adding to the bath a soluble cyanide complex which is capable of forming an insoluble compound by reacting with ferric ions in the bath, measuring the concentration of ferric ions in the bath, and adjusting the amount of said soluble cyanide complex added to the bath during the treating in order to keep the amount of ferric ions in the bath permanently between 0.1 and 30 mg/kg.
References Cited (Backward Citations)
US2831814A
Cited
US3440170A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-05 | 1987-03-07 | 1987-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-05 | 1991-03-07 | 1991-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-05 | 1995-03-07 | 1995-09-06 | $7700.00 | Window Closed / Lapsed |