EP0025624B1 - Procédé pour inhiber la corrosion d'une installation métallique au contact d'un bain acide - Google Patents

Procédé pour inhiber la corrosion d'une installation métallique au contact d'un bain acide Download PDF

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Publication number
EP0025624B1
EP0025624B1 EP80200835A EP80200835A EP0025624B1 EP 0025624 B1 EP0025624 B1 EP 0025624B1 EP 80200835 A EP80200835 A EP 80200835A EP 80200835 A EP80200835 A EP 80200835A EP 0025624 B1 EP0025624 B1 EP 0025624B1
Authority
EP
European Patent Office
Prior art keywords
bath
installation
ferric ions
process according
corrosion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP80200835A
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German (de)
English (en)
French (fr)
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EP0025624A1 (fr
Inventor
Daniel Tytgat
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Solvay SA
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Solvay SA
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Publication date
Application filed by Solvay SA filed Critical Solvay SA
Priority to AT80200835T priority Critical patent/ATE3782T1/de
Publication of EP0025624A1 publication Critical patent/EP0025624A1/fr
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Publication of EP0025624B1 publication Critical patent/EP0025624B1/fr
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/04—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in markedly acid liquids
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/04—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors

Definitions

  • the present invention relates to a method for inhibiting corrosion of metallic installations in contact with an acid bath. It relates more particularly to a process for inhibiting corrosion, in contact with aqueous baths containing a mineral acid, of installations made up of metals less noble than hydrogen in these baths.
  • pickling and descaling techniques are commonly exported in the industry, where they are used in particular for the descaling of steel boilers and for the descaling of crystallization reactors such as steel or cast iron columns used for crystallization of sodium bicarbonate in the process for the manufacture of soda with ammonia or the nickel evaporators used for the crystallization of sodium chloride from brines or aqueous solutions of sodium chloride and sodium hydroxide.
  • the acid baths used in these pickling and descaling processes must generally contain a corrosion inhibitor whose role is to avoid deterioration of the installation without harming the pickling or descaling action of the bath.
  • Corrosion inhibitors added to acid baths also have the function of preventing corrosion of installations used for their handling, in particular storage tanks, manifolds and their accessories such as valves, valves and pumps.
  • alkylpyridinium chloride As a corrosion inhibitor, it has been observed, in practice, that despite the presence of alkylpyridinium chloride in the acid baths, these nevertheless cause, in some cases, corrosion, sometimes rapid, of the installation.
  • a known method to remedy this drawback consists in adding stannous chloride to the bath, in addition to the alkylpyridinium chloride.
  • etching paste made up of a mixture of phosphoric acid, potassium ferrocyanide, urea, phosphate. zinc, sawdust, molasses and decylpyridinium chloride (Chemical Abstracts, 1976, vol. 85, no. 97486d).
  • the invention aims to remedy the aforementioned drawbacks of known methods, by providing a method for preventing corrosion of metallic installations in contact with acid baths containing alkylpyridinium chloride, which is both inexpensive and harmless for the environment. .
  • the invention therefore relates to a method for inhibiting corrosion in contact with an aqueous bath containing a mineral acid, alkylpyridinium chloride and Ferric ions, of an installation made of a metal less noble than hydrogen in said bath or an alloy containing such a metal; according to the invention, a soluble cyanide complex is added to the bath, capable of forming an insoluble compound by reaction with the ferric ions of the bath, the cyanide complex being added to the bath in an amount adjusted between that necessary to maintain in the bath, at contact with the installation, a concentration of ferric ions equal to 30 mg / kg and that strictly necessary to obtain a zero concentration of ferric ions.
  • the expression "metal less noble than hydrogen in the bath” is intended to denote any metal whose equilibrium potential in the acidic aqueous bath considered is less than the equilibrium potential of hydrogen in the same bath and under the same conditions of use. In other words, these are metals which, in the event of corrosion in contact with the bath, generate hydrogen evolution (Atlas of electrochemical equilibria - M. Pourbaix - Gauthier - Villars & Cie, Editeurs - 1963 - p. 75 and 76). Chromium, iron, cobalt, nickel and zinc are examples of metals which fall within the scope of the invention.
  • alloy of such a metal is intended to denote all the alloys of which at least one of the constituent elements is a metal less noble than hydrogen, as defined above. It therefore designates both alloys less noble than hydrogen (for example ordinary steel and cast iron) and alloys more noble than hydrogen (for example cupronickels which are nickel and copper alloys containing from 70 to 85% copper).
  • the choice of mineral acid for the bath is not critical and essentially depends on the nature of the treatment.
  • the mineral acid is advantageously hydrochloric acid
  • the bath consisting for example of an aqueous solution containing 0.01 to 3 moles of hydrochloric acid per liter.
  • a normal hydrochloric acid solution is particularly suitable as a bath for the treatment of iron or iron alloy installations.
  • alkylpyridinium chloride The function of alkylpyridinium chloride is to prevent corrosion of the installation by acid. It is preferably chosen from those derived from alkanes having from 10 to 18 carbon atoms. Cetyl-, myristyl- and laurylpyridinium chloride have been found to be particularly advantageous.
  • the content of alkylpyridinium chloride in the bath depends on various factors, in particular the choice of acid, the concentration, the bath in this acid, the temperature of the bath, the nature of the material of the installation, the duration of treatment of the installation with the bath and choice of alkylpyridinium chloride. It can be determined in each particular case by routine laboratory work.
  • the bath is a normal solution of hydrochloric acid
  • good results are generally obtained by fixing the content of alkylpyridinium chloride in the bath between 0.5 and 5000 mg / kg, preferably between 2 and 500 mg / kg.
  • Preferred baths for the treatment of mild steel or cast iron installations are normal hydrochloric acid solutions containing about 75 to 200 mg of laurylpyridinium chloride per kg of solution.
  • a soluble cyanide complex is added to the bath, capable of reacting with ferric ions of the bath to form an insoluble compound.
  • ferric ions in the bath can come from various sources. They can in particular come from the installation itself, when the latter is made of iron or an iron alloy, either because they result from corrosion of the installation, or because they are located in an inlay dissolved in the bath in the case of a descaling treatment. These ions can also result from local corrosion of an iron-based element, external to the installation proper and with which the bath is brought into temporary contact.
  • Cyanide complexes constitute a class of very stable chemical complexes, well known in the art (Encyclopedia of Chemical Technology - Kirk & Othmer - The Interscience Encyclopedia, Inc. - 19 - Vol. 4, p. 677 to 680). They consist of complex anions containing at least one central metallic atom linked by coordination to cyanide groups.
  • the cyanide complex must be chosen from those which are soluble in acidic aqueous baths and which, by reaction with ferric ions, form insoluble cyanide compounds.
  • ferricyanide and ferrocyanide complexes are examples of cyanide complexes which are very suitable in the context of the invention.
  • tetravalent cyanide complexes and more particularly ferrocyanide.
  • the cyanide complex can be introduced into the bath in the form of a water-soluble compound.
  • Water-soluble compounds which have been found to be particularly advantageous are hexacyanoferric acid and ferrocyanides of calcium, ammonium, sodium and potassium, potassium ferrocyanide being preferred.
  • the addition of soluble cyanide complex should be limited to the maximum of the quantity strictly necessary to achieve a zero concentration of ferric ions in the bath, in the immediate vicinity of the installation.
  • the quantity of this soluble cyanide complex added to the bath must moreover be sufficient to maintain the residual content of ferric ions in the bath in the vicinity of the installation, at all times below a critical value from which their influence on corrosion of the installation becomes unacceptable.
  • the fixing of the above critical value of the residual content of ferric ions in the bath in the vicinity of the installation will depend on a large number of parameters, such as the nature of the material of the installation, the nature and concentration of the mineral acid in the bath, the temperature of the bath, the duration of the treatment.
  • Values which are very suitable for the quantity of cyanide complex added to the bath are those which lead to obtaining a residual content of ferric ions in the bath in contact with the installation, of between 20 and 0.5 mg / kg , preferably between 5 and 1 mg / kg.
  • Any suitable technique can be used to control the amount of cyanide complex added to the bath.
  • the quantity of soluble cyanide complex added to the bath is adjusted by measuring the potential of the material of the installation in the bath.
  • the magnitude of the potential of the material of the installation in the bath is a measure of its content of ferric ions.
  • the method used to measure the potential of the installation material in the bath is not critical.
  • an electrochemical measuring cell comprising a reference electrode (for example a hydrogen electrode or a calomel electrode) and a working electrode executed in the same material as the installation and immersed in the bath in the immediate vicinity of the installation.
  • the working electrode can be a metal bar, for example, a cylindrical bar.
  • an area of the installation which is in contact with the bath for example the wall of a tank, a pipe, the shutter valve of a valve or the impeller or volute of a pump.
  • the method according to the invention finds an interesting application for the descaling of evaporators made of nickel or of nickel alloy used to crystallize sodium chloride from caustic brines produced by electrolysis of a sodium chloride brine in a cell. permeable diaphragm electrolysis.
  • Another interesting application of the process according to the invention lies in the descaling of the refrigeration zone of the columns used for the crystallization of sodium bicarbonate in the process for the manufacture of soda with ammonia (Manufacture of soda - Te-Pang Hou - Hafner Publishing Co - 1969).
  • the method according to the invention can also be applied to the handling of mineral acids in aqueous solution, in metal pipes or tanks.
  • the material of the installation is an alloy comprising both a metal less noble than hydrogen, as defined above, and a metal more noble than hydrogen
  • Potassium iodide is a preferred substance for inhibiting corrosion of such metals.
  • cupronickels which are nickel and copper alloys generally containing from 70 to 85% of copper and from 15 to 30% of nickel (Treaty of Structural Metallurgy - A. De Sy and J. Vidts - Dunod - 1962 - p. 184).
  • an electrochemical measuring cell comprising a working electrode, executed in the material studied and immersed in a normal aqueous solution of hydrochloric acid, containing, per kg, 100 mg of the product known under the name "Dehyquart C "(Henkel Int. GmbH) which consists mainly of laurylpyridinium chloride.
  • the working electrode consisted of a cylindrical bar whose surface in contact with the bath had an area equal to 10 cm 2 .
  • the test was carried out with an ordinary steel working electrode.
  • the second phase of the test was immediately started, during which five consecutive additions of potassium ferrocyanide trihydrate were made to the solution of the measuring cell.
  • the consecutive additions of potassium ferrocyanide were adjusted so that its residual content of ferric ions was successively reduced to 300, 100, 30, 10 and 0 mg / kg.
  • the results of this second phase of the test are listed in Table II.
  • the results of the two phases of the test are reproduced in the diagram in FIG. 1, in which the abscissa scale represents the equilibrium potential of the working electrode of the measurement cell, expressed in mV and the scale ordinate is a logarithmic scale of the intensity of the electric current in the working electrode expressed in p, A per cm 2 of the immersed surface of the electrode.
  • the curve in unbroken lines reproduces the results of the first phase of the test and shows the unfavorable action of ferric ions on the corrosion of the electrode.
  • the dashed line reproduces the results of the second phase of the test: it shows, on the one hand, that the harmful influence of ferric ions is inhibited by additions of potassium ferrocyanide and, on the other hand, that the addition of potassium ferrocyanide decreases the equilibrium potential of the metal towards a fixed limit value.
  • Example 2 The two phases of the test of Example 1 were repeated with a working electrode of grade 316 L steel (ASTM standards) which is an austenitic stainless steel of the following weight composition (Engineering Techniques - Metallurgy - Vol . 1 - Form M 323 - 17 - 1974):

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
EP80200835A 1979-09-17 1980-09-05 Procédé pour inhiber la corrosion d'une installation métallique au contact d'un bain acide Expired EP0025624B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80200835T ATE3782T1 (de) 1979-09-17 1980-09-05 Verfahren zur korrosionshemmung beim kontakt mit einem saeurebad fuer eine metallische anlage.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7923283A FR2465010A1 (fr) 1979-09-17 1979-09-17 Procede pour inhiber la corrosion d'une installation metallique au contact d'un bain acide
FR7923283 1979-09-17

Publications (2)

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EP0025624A1 EP0025624A1 (fr) 1981-03-25
EP0025624B1 true EP0025624B1 (fr) 1983-06-15

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EP80200835A Expired EP0025624B1 (fr) 1979-09-17 1980-09-05 Procédé pour inhiber la corrosion d'une installation métallique au contact d'un bain acide

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US (1) US4402759A (enrdf_load_stackoverflow)
EP (1) EP0025624B1 (enrdf_load_stackoverflow)
AT (1) ATE3782T1 (enrdf_load_stackoverflow)
DE (1) DE3063776D1 (enrdf_load_stackoverflow)
FR (1) FR2465010A1 (enrdf_load_stackoverflow)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3161291D1 (en) * 1980-01-08 1983-12-08 Central Electr Generat Board Descaling process
FR2578271A1 (fr) * 1985-03-04 1986-09-05 Solvay Bains et procede pour le polissage chimique de surfaces en acier.
FR2582675B1 (fr) * 1985-06-03 1992-10-02 Solvay Bains et procedes pour le polissage chimique de surfaces en acier inoxydable
RU2450497C2 (ru) * 2010-05-13 2012-05-20 Федеральное государственное образовательное учреждение высшего профессионального образования Российский Государственный аграрный университет - Московская сельскохозяйственная академия имени К.А. Тимирязева (ФГОУ ВПО РГАУ - МСХА имени К.А. Тимирязева) Агрегат для обработки почвы рыхлением
WO2017112721A1 (en) * 2015-12-22 2017-06-29 Albemarle Corporation Corrosion inhibitors and related processes for their production and use

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL79915C (enrdf_load_stackoverflow) * 1950-10-27
US2831814A (en) * 1951-12-19 1958-04-22 Poor & Co Acid pickling of metals and compositions therefor
FR1182531A (fr) * 1957-09-10 1959-06-25 Poor & Co Procédé pour le décapage acide de métaux et produits utilisés pour la mise en oeuvre de ce procédé
FR1353512A (fr) * 1962-12-21 1964-02-28 T E B Sa Inhibition de l'action corrosive des eaux de faible dureté
NL155315B (nl) * 1964-06-09 1977-12-15 Ver Kunstmestfabriekn Mekog Al Werkwijze voor het reinigen van ijzeren of stalen, inwendige oppervlakken van industriele apparatuur

Also Published As

Publication number Publication date
EP0025624A1 (fr) 1981-03-25
US4402759A (en) 1983-09-06
FR2465010B1 (enrdf_load_stackoverflow) 1982-10-08
FR2465010A1 (fr) 1981-03-20
DE3063776D1 (en) 1983-07-21
ATE3782T1 (de) 1983-06-15

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