EP0346510A1 - Pickling of semi-finished products - Google Patents

Pickling of semi-finished products Download PDF

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Publication number
EP0346510A1
EP0346510A1 EP19880109498 EP88109498A EP0346510A1 EP 0346510 A1 EP0346510 A1 EP 0346510A1 EP 19880109498 EP19880109498 EP 19880109498 EP 88109498 A EP88109498 A EP 88109498A EP 0346510 A1 EP0346510 A1 EP 0346510A1
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Prior art keywords
iron
solution
iii
pickling
chloride solution
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EP19880109498
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German (de)
French (fr)
Inventor
Markus Dr. Dipl.-Ing. Bringmann
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CHEMA CHEMIEMASCHINEN GmbH
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CHEMA CHEMIEMASCHINEN GmbH
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Priority to DE19873719604 priority Critical patent/DE3719604A1/en
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Priority to EP19880109498 priority patent/EP0346510A1/en
Publication of EP0346510A1 publication Critical patent/EP0346510A1/en
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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
    • 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
    • C23G1/08—Iron or steel
    • 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
    • C23G1/36—Regeneration of waste pickling liquors

Definitions

  • the invention relates to the pickling of semi-finished products.
  • wet processes such as e.g. B. pickling used.
  • the sulfuric acid pickling which is very common in this industry, is often used for reasons of low operating costs.
  • large amounts of iron sulfate solutions are continuously generated according to the reaction Fe0 + SO4 ⁇ FeSO4
  • These spent sulfuric acid pickling solutions with an iron content of approx. 100-150 g / l, which are generally known under the name "green acid” have to be dumped in the North Sea or disposed of by expensive treatment.
  • the first method is neutralization with lime, according to the reaction FeSO4 + Ca (OH) 2 ⁇ Fe (OH) 2 + CaSO4 large quantities of iron hydroxides and gypsum are produced, which are finally brought to landfill sites.
  • Pickling one ton of steel produces around 50 kg of iron sulfate, of which around 80 kg of iron hydroxides and 120 kg of gypsum are formed during neutralization. If you consider that millions of tons of steel are pickled annually in Germany, you can immediately see the size of this waste dump.
  • the second disposal method which is even more expensive and rarely used, is the processing of the used pickling solution freezes to the so-called iron vitriol, which is pure iron sulfate powder.
  • iron vitriol which is pure iron sulfate powder.
  • the demand in the industry for this product is so small that the steelworks sell the expensive chemical for free. If all steelworks are equipped with freezing systems due to the legal requirements, the waste will not be in liquid but in powdery form due to the lack of buyers.
  • the object of the invention is to carry out the pickling of semi-finished products more economically and in particular in an environmentally compatible manner.
  • the invention teaches the use of an acidic iron (III) chloride solution for pickling semi-finished products.
  • This solution is preferably obtained by adding hydrochloric acid to an HCl concentration of 0.5 to 2 mol / dm3 solution, in particular 1 , 0 mol / dm3 solution set.
  • the use with up to 45 wt .-%, in particular 40 wt .-% FeCl3 is recommended.
  • the invention is based on the knowledge that the iron (III) chloride solutions hitherto used only for etching metals can in principle also be used for pickling and show surprisingly good results. That appropriate measures have not been tried so far, is probably due to the previously too high acquisition costs or ineffective or dangerous regeneration options. However, these obstacles have now been removed.
  • the invention relates to the preferred use of iron (III) chloride solutions which have at least partially been obtained by electrolytic regeneration of at least partially used iron (III) chloride pickling solution.
  • the continuous process for the continuous regeneration of iron chloride solutions is based on the anodic oxidation of iron (II) ions to iron (III) ions according to the reaction Fe+2 - e ⁇ ⁇ Fe+3 in a series of anolyte cells, which are isolated from cathodes using anionper mable ion exchange membrane are separated.
  • a sodium chloride solution acidified with hydrochloric acid is used as the catholyte.
  • 2 H3O+ + 2 e ⁇ ⁇ H ⁇ + 2 H2O free hydrogen gas is formed from the hydronium ions belonging to the dissociated hydrochloric acid.
  • the current flow in both electrolytes takes place through the movement of chloride ions from the catholyte into the anolyte or the iron chloride solution, where they form the dissociated iron (III) chloride with the iron (III) ions formed according to the above reaction, which with the summary response Fe+3 +3 Cl ⁇ (from Katholytlsg.) ⁇ FeCl3 can be represented.
  • the anodic oxidation process is monitored and regulated by measuring the reduction and oxidation potential of the iron chloride solution.
  • This iron (III) chloride solution which has a market concentration of 40% by weight, is an economic commodity and can be sold to metal etching plants for the production of etched molded parts or printed circuit boards as well as to industrial and municipal sewage treatment plants for sludge conditioning. With a current iron (III) chloride price of around DM 200, - / ton this is an interesting cost factor.
  • the invention further relates to a device for the continuous electrolytic regeneration of an at least partially used, in particular an iron (III) chloride solution used for pickling metals, consisting of an electrolytic cell container which, with the aid of at least one ion exchange membrane, is placed in a catholyte space filled with a catholyte is subdivided with at least one cathode and into at least one anolyte space filled with the iron (III) chloride solution as the anolyte, each with an anode, a feed line supplying continuously also partially used solution and a return line discharging continuously regenerated solution.
  • This device is characterized in that the ion exchange membrane in each case consists of a 0.05 to 0.50 mm thick carrier film made of polyester, polyethylene or polyvinyl chloride with an exchange resin applied.
  • the carrier film material is preferably fluorinated.
  • the applied exchange resin consists of vinyl pyridinium halide, in particular bromide.
  • Such ion exchange membranes are particularly suitable if they have a specific electrical resistance of at most 7 ohms / cm 2, a selectivity of 65 to 90% (0.5 N KC1) and a transport number t_ of 0.75 to 0.85. Ion exchange membranes with the properties mentioned are commercially available for other areas of application.
  • the catholyte consists of an acidic alkali metal chloride solution which is kept constant in a pH range from 0.5 to 6.5 by means of a pH measuring device which is coupled to a hydrochloric acid metering pump.
  • the arrangement should be such that the pickled non-ferrous metals can be transferred through the ion exchange membrane into the catholyte solution, from which they can be automatically removed by periodic pH increases, precipitation and filtration.
  • the invention is based on the knowledge that the ion exchange membranes mentioned are practically ideal for the regeneration of at least partially used solutions. Uncontrollable catholyte / anolyte mixtures are no longer possible. Due to the low specific electrical resistance of the ion exchange membrane, a low voltage drop and thus energy consumption is guaranteed. There is no problematic waste disposal. Dissolved, non-ferrous metal ions are transferred through the membrane into the catholyte, from which they are easily removed, the regenerated In this respect, the solution is not saturated.
  • the device shown in top view in the single figure serves for the continuous electrolytic regeneration of an at least partially used etching solution in the form of an iron (III) chloride solution used for etching metals and consists in its basic structure of an electrolytic cell container 1.
  • anolyte cells 2 are used, in which anodes 3 made of plastic-impregnated graphite are attached. Between the anolyte cells 2 there are 4 cathodes 5 in a common catholyte space.
  • Ion exchange membranes 6 are attached in the walls of the anolyte cells 2 in such a way that they separate the anolyte space 7 from the catholyte space 4 in an absolutely tight manner.
  • ion exchange membranes 6 each consist of an approximately 0.2 mm thick polytetrafluoroethylene film with grafted quaternary vinylpyridinium bromide.
  • the catholyte space 4 is filled with an alkali metal chloride solution, which is guided in a circuit by means of a pump 11 via the lines 8.
  • the pump 11 is followed by a heat exchanger 12 for cooling the solution, if necessary.
  • the pH of the catholyte solution is continuously regulated by means of a measuring device 14, which automatically controls a hydrochloric acid metering pump 13, and is thus kept at a desired level.
  • the filter 15 connected behind the measuring device 14 serves to separate the precipitated metal hydroxides.
  • the solution to be regenerated is introduced uniformly into the anolyte spaces 7 via feed lines 9.
  • the processed etching medium is returned via a return line 10 to a pickling machine (not shown) or a storage tank.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • ing And Chemical Polishing (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Abstract

In a process for pickling semifinished products, an acidic iron(III) chloride solution is used, appropriate apparatus consists of an electrolytic cell container (1) with at least one ion exchanger membrane (6). This ion exchanger membrane consists in each case of a 0.05 to 0.50 mm thick carrier film of polyester, polyethylene or polyvinyl chloride with applied exchanger resin. (To be published with the sole figure in the drawing) <IMAGE>

Description

Die Erfindung betrifft das Beizen von Halbzeugen. In der Stahl­industrie werden u. a. während der Halbzeugverarbeitung zur Ent­fernung von Zunder und Rost aus der Metalloberfläche Naßprozesse, wie z. B. das Beizen, eingesetzt. Für das Stahlbeizen wird bis jetzt überlicherweise ausschließlich Schwefelsäure und seltener Salzsäure in sehr großen Mengen verwendet. Das in dieser Branche sehr verbreite­te Schwefelsäure-Beizen wird aus Gründen der niedrigen Betriebs­kosten gerne eingesetzt. Während dieses Prozesses entstehen kontinu­ierlich große Mengen an Eisensulfatlösungen gemäß der Reaktion
Fe⁰ + SO₄→ FeSO₄
Diese verbrauchten Schwefelsäure-Beizlösungen mit einem Eisengehalt von ca. 100-150 g/l, die allgemein unter dem Namen "Grünsäure" be­kannt sind, müssen in der Nordsee verklappt oder auch durch kosten­intensive Behandlung entsorgt werden.The invention relates to the pickling of semi-finished products. In the steel industry, wet processes such as e.g. B. pickling used. Up to now, only large quantities of sulfuric acid and, more rarely, hydrochloric acid have been used for steel pickling. The sulfuric acid pickling, which is very common in this industry, is often used for reasons of low operating costs. During this process, large amounts of iron sulfate solutions are continuously generated according to the reaction
Fe⁰ + SO₄ → FeSO₄
These spent sulfuric acid pickling solutions with an iron content of approx. 100-150 g / l, which are generally known under the name "green acid", have to be dumped in the North Sea or disposed of by expensive treatment.

Es gibt heute grundsätzlich zwei Entsorgungsmethoden dieser Beizrück­stände. Das erste Verfahren ist die Neutralisation mit Kalk, wobei gemäß der Reaktion
FeSO₄ + Ca(OH)₂→ Fe(OH)₂ + CaSO₄
große Mengen an Eisenhydroxiden und Gips entstehen, die schließlich auf Sondermülldeponien gebracht werden. Beim Beizen von einer Tonne Stahl fallen rund 50 kg Eisensulfat an, wovon während der Neutra­lisation ca. 80 kg Eisenhydroxide und 120 kg Gips entstehen. Wenn man bedenkt, daß in Deutschland jährlich Millionen Tonnen Stahl gebeizt werden, erkennt man sofort die Größe dieser Abfallhalde.There are basically two methods of disposing of these pickling residues today. The first method is neutralization with lime, according to the reaction
FeSO₄ + Ca (OH) ₂ → Fe (OH) ₂ + CaSO₄
large quantities of iron hydroxides and gypsum are produced, which are finally brought to landfill sites. Pickling one ton of steel produces around 50 kg of iron sulfate, of which around 80 kg of iron hydroxides and 120 kg of gypsum are formed during neutralization. If you consider that millions of tons of steel are pickled annually in Germany, you can immediately see the size of this waste dump.

Das zweite Entsorgungsverfahren, das noch kostenintensiver ist und selten eingesetzt wird, ist das Verarbeiten der verbrauchten Beizlö­ sungen durch Ausfrieren zum sogenannten Eisenvitriol, das reines Eisensulfatpulver darstellt. Der Bedarf in der Industrie an diesem Produkt ist jedoch so gering, daß die Stahlwerke die teuer herge­stellte Chemikalie kostenlos abgeben. Wenn aufgrund der gesetzlichen Auflagen alle Stahlwerke mit Ausfrierungsanlagen ausgestattet werden, wird man den Abfall aufgrund des Mangels an Abnehmern nicht in flüssiger, sondern in pulvriger Reinstform haben.The second disposal method, which is even more expensive and rarely used, is the processing of the used pickling solution freezes to the so-called iron vitriol, which is pure iron sulfate powder. However, the demand in the industry for this product is so small that the steelworks sell the expensive chemical for free. If all steelworks are equipped with freezing systems due to the legal requirements, the waste will not be in liquid but in powdery form due to the lack of buyers.

Ähnliche Probleme treten beim Salzsäurebeizen auf. Die gemäß der Reaktion
Fe⁰ + 2 Cl⁻→ FeCl₂
entstehenden Eisenchloride werden praktisch ausschließlich neutrali­siert und enden ebenfalls in Form von Eisenhydroxiden auf Sonder­mülldeponien.Similar problems occur with hydrochloric acid pickling. According to the reaction
Fe⁰ + 2 Cl⁻ → FeCl₂
The resulting iron chlorides are neutralized practically exclusively and also end up in the form of iron hydroxides in hazardous waste disposal sites.

Der Erfindung liegt die Aufgabe zugrunde, das Beizen von Halbzeugen wirtschaftlicher und insbesondere umweltkonformer durchzuführen.The object of the invention is to carry out the pickling of semi-finished products more economically and in particular in an environmentally compatible manner.

Zur Lösung dieser Aufgabe lehrt die Erfindung die Verwendung einer sauren Eisen(III)-chlorid-Lösung zum Beizen von Halbzeugen, Vorzugs­weise ist diese Lösung durch Zugabe von Salzsäure auf eine HCl-Kon­zentration von 0,5 bis 2 mol/dm³ Lösung, insbesondere 1,0 mol/dm³ Lösung eingestellt. Außerdem empfiehlt sich die Verwendung mit bis 45 Gew.-%, insbesondere 40 Gew.-% FeCl₃.To achieve this object, the invention teaches the use of an acidic iron (III) chloride solution for pickling semi-finished products. This solution is preferably obtained by adding hydrochloric acid to an HCl concentration of 0.5 to 2 mol / dm³ solution, in particular 1 , 0 mol / dm³ solution set. In addition, the use with up to 45 wt .-%, in particular 40 wt .-% FeCl₃ is recommended.

Die Erfindung geht hierbei von der Erkenntnis aus, daß die bisher nur zum Ätzen von Metallen eingesetzten Eisen(III)-chlorid-Lösungen grundsätzlich auch zum Beizen eingesetzt werden können und dabei überraschend gute Ergebnisse zeigen. Daß entsprechende Maßnahmen bisher nicht versucht worden sind, ist vermutlich auf die bisher zu hohen Anschaffungskosten bzw. wenig wirksamen bzw. gefährlichen Regenerierungsmöglichkeiten zurückzuführen. Diese Hinderungsgründe konnten jedoch jetzt beseitigt werden. Gegenstand der Erfindung ist insoweit die bevorzugte Verwendung von Eisen(III)-chlorid-Lösungen, die zumindest teilweise durch elektrolytische Regeneration zumindest teilweise verbrauchter Eisen(III)-chlorid-Beizlösung erhalten worden sind.The invention is based on the knowledge that the iron (III) chloride solutions hitherto used only for etching metals can in principle also be used for pickling and show surprisingly good results. That appropriate measures have not been tried so far, is probably due to the previously too high acquisition costs or ineffective or dangerous regeneration options. However, these obstacles have now been removed. In this respect, the invention relates to the preferred use of iron (III) chloride solutions which have at least partially been obtained by electrolytic regeneration of at least partially used iron (III) chloride pickling solution.

Im folgenden wird die Erfindung näher erläutert:The invention is explained in more detail below:

Ein wichtiger Teil eines abwasserfreien und somit gesetzeskonformen Systems ist der Einsatz einer Dampfspülkammer oder Kaskadenpülsek­tion, die für eine besonders kleine Spülwassermenge sorgt. Diese Spülwasser werden nämlich im Prozeß weiterverarbeitet. Der wich­tigste Bestandteil des neuen Beizsystems ist jedoch die Anlage zur kontinuierlichen Regeneration der Beizlösung. Während des Stahlbei­zens entstehen aus Eisen(III)-chlorid und Eisenoxiden sowie metal­lischen Eisen gemäß der Reaktion
Fe⁰ + 2 Fe⁺³ + 6Cl⁻→ 3 Fe⁺² + 6 Cl⁻
kontinuierlich Eisen(II)-Ionen, die ebenfalls kontinuierlich zu Eisen(III)-Ionen oxidiert werden müssen, wobei jede chemische Um­wandlung, wie z. B. mit Wasserstoffperoxid und Salzsäure, aufgrund des sehr großen Chemikalienbedarfs ausgeschlossen wäre. Das Durch­laufverfahren zur kontinuierlichen Regeneration von Eisenchloridlö­sungen basiert auf der anodischen Oxidation von Eisen(II)-Ionen zu Eisen(III)-Ionen gemäß der Reaktion
Fe⁺² - e⁻→ Fe⁺³
in einer Reihe von Anolytzellen, die von Kathoden mittels anionper­ meablen Ionenaustauschermembran abgetrennt sind. Als Katholyt wird eine mit Salzsäure angesäuerte Natriumchloridlösung eingesetzt. Wäh­rend der Kathodenreaktion gemäß der Reaktion
2 H₃O⁺ + 2 e⁻ → H

Figure imgb0001
↑ + 2 H₂O
entsteht aus den dissoziierten Salzsäure zugehörigen Hydronium­ionen freies Wasserstoffgas. Der Stromfluß in beiden Elektrolyten er­folgt durch die Bewegung von Chloridionen aus dem Katholyten in den Anolyt bzw. die Eisenchloridlösung, wo sie mit dem gemäß der oben stehenden Reaktion entstehenden Eisen(III)-Ionen das dissoziier­te Eisen(III)-chlorid bilden, was mit der summarischen Reaktion
Fe⁺³ +3 Cl⁻ (aus Katholytlsg.)→ FeCl₃
dargestellt werden kann. Der anodische Oxidationsprozeß wird mittels Messung von Reduktions- und Oxidationspotential der Eisenchlorid­lösung überwacht und geregelt.An important part of a wastewater-free and therefore legally compliant system is the use of a steam rinsing chamber or cascade rinsing section, which ensures a particularly small amount of rinsing water. This rinse water is processed in the process. The most important component of the new pickling system, however, is the system for the continuous regeneration of the pickling solution. During the steel pickling process, iron (III) chloride and iron oxides as well as metallic iron are formed according to the reaction
Fe⁰ + 2 Fe⁺³ + 6Cl⁻ → 3 Fe⁺² + 6 Cl⁻
continuously iron (II) ions, which must also be continuously oxidized to iron (III) ions, any chemical transformation, such as. B. with hydrogen peroxide and hydrochloric acid, would be excluded due to the very large chemical requirement. The continuous process for the continuous regeneration of iron chloride solutions is based on the anodic oxidation of iron (II) ions to iron (III) ions according to the reaction
Fe⁺² - e⁻ → Fe⁺³
in a series of anolyte cells, which are isolated from cathodes using anionper mable ion exchange membrane are separated. A sodium chloride solution acidified with hydrochloric acid is used as the catholyte. During the cathode reaction according to the reaction
2 H₃O⁺ + 2 e⁻ → H
Figure imgb0001
↑ + 2 H₂O
free hydrogen gas is formed from the hydronium ions belonging to the dissociated hydrochloric acid. The current flow in both electrolytes takes place through the movement of chloride ions from the catholyte into the anolyte or the iron chloride solution, where they form the dissociated iron (III) chloride with the iron (III) ions formed according to the above reaction, which with the summary response
Fe⁺³ +3 Cl⁻ (from Katholytlsg.) → FeCl₃
can be represented. The anodic oxidation process is monitored and regulated by measuring the reduction and oxidation potential of the iron chloride solution.

Während des Beizens findet eine Metallauflösung in der Prozeßlösung statt, was die Steigerung der Dichte ender Eisenchloridlösung zur Folge hat. Diese Dichteänderung wird in einem elektromechanischen Dichte­regler erfaßt und mit den Spülwässern automatisch korrigiert. Somit wird während des Beizens eine neue Eisenchloridlösung, die im Sam­melbehälter aufgefangen wird, hergestellt. diese Eisen(III)-chlorid-­Lösung, die eine marktübliche Konzentration von 40 Gew.-% aufweist, ist ein Wirtschaftsgut und kann an Metallätzwerke zur Herstellung von Ätzformteilen oder Leiterplatten sowie an industrielle und kommu­nale Kläranlagen zur Schlammkonditionierung verkauft werden. Bei einem derzeitigen Eisen(III)-chlorid-preis von rund DM 200,--/Tonne ist das ein interessanter Kostenfaktor.During pickling, metal dissolution takes place in the process solution, which leads to an increase in the density of the iron chloride solution. This change in density is recorded in an electromechanical density controller and automatically corrected with the rinse water. A new ferric chloride solution, which is collected in the collecting container, is thus produced during the pickling process. This iron (III) chloride solution, which has a market concentration of 40% by weight, is an economic commodity and can be sold to metal etching plants for the production of etched molded parts or printed circuit boards as well as to industrial and municipal sewage treatment plants for sludge conditioning. With a current iron (III) chloride price of around DM 200, - / ton this is an interesting cost factor.

Die Vorteile dieser Handhabung sind zu sehen in dem umweltkonformen Kreislaufprozeß, weil keine Spülwässer anfallen, der gleichmäßigen Beizgeschwindigkeit, die eine sprunghafte Erhöhung der Produktqua­lität und Steigerung der Kapazitäten der bestehenden Beizanlagen (im Vergleich zum Schwefelsäurebeizen) bewirkt, den geringen Betriebs­kosten (Energieverbrauch ca. 4 kWh/kg Fe⁺²→ Fe⁺³), Ertrag aus gewonnener Eisen(III)-chlorid-Lösung, der Unabhängigkeit von Alt­lösungsentsorgungen und der damit einhergehenden erhöhten Produk­tionssicherheit und schließlich und endlich der fehlenden Emmission von Salzsäuredämpfen (erhöhte Ergonomie der Arbeitsplätze).The advantages of this handling can be seen in the environmentally friendly cycle process, because there are no rinsing water, the uniform pickling speed, which leads to a sudden increase in product quality and the capacity of the existing pickling plants (compared to sulfuric acid pickling), the low operating costs (energy consumption approx. 4 kWh / kg Fe⁺² → Fe⁺³), yield from iron (III) chloride solution obtained, independence from waste solution disposal and the associated increased production security and finally and finally the lack of emission of hydrochloric acid vapors (increased ergonomics of the workplaces).

Gegenstand der Erfindung ist ferner eine Vorrichtung zum kontinuier­lichen elektrolytischen Regenerieren einer zumindest teilweise ver­brauchten, insbesondere einer zum Beizen von Metallen eingesetzten Eisen(III)-chlorid-Lösung, bestehend aus einem Elektrolysezellenbe­hälter, der mit Hilfe wenigstens einer Ionenaustauschermembran in einen mit einem Katholyten gefüllten Katholytraum mit wenigstens einer Kathode und in wenigstens einen mit der Eisen(III)-chlorid-­Lösung als Anolyten gefüllten Anolytraum mit jeweils einer Anode, einer kontinuierlich auch teilweise verbrauchte Lösung zuführenden Zuleitung und einer kontinuierlich regenerierte Lösung abführenden Rückführleitung unterteilt ist. Diese Vorrichtung ist dadurch gekenn­zeichnet, daß die Ionenaustauschermembran jeweils aus einer 0,05 bis 0,50 mm starken Trägerfolie aus Polyester, Poläthylen oder Polyvinylchlorid mit aufgebrachtem Austauscherharz besteht.The invention further relates to a device for the continuous electrolytic regeneration of an at least partially used, in particular an iron (III) chloride solution used for pickling metals, consisting of an electrolytic cell container which, with the aid of at least one ion exchange membrane, is placed in a catholyte space filled with a catholyte is subdivided with at least one cathode and into at least one anolyte space filled with the iron (III) chloride solution as the anolyte, each with an anode, a feed line supplying continuously also partially used solution and a return line discharging continuously regenerated solution. This device is characterized in that the ion exchange membrane in each case consists of a 0.05 to 0.50 mm thick carrier film made of polyester, polyethylene or polyvinyl chloride with an exchange resin applied.

Für die weitere Ausgestaltung bestehen auch hier mehrere Möglichkei­ten. So ist das Trägerfolienmaterial vorzugsweise fluorisiert. Das aufgebrachte Austauscherharz besteht nach einer bevorzugten Aus­führungsform aus Vinylpyridiniumhalogenid, insbesondere -bromid. Besonders geeignet sind solche Ionenaustauschermembranen, sofern sie einen spezifischen elektrischen Widerstand von höchstens 7 Ohm/­cm², eine Selektivität von 65 bis 90 % (0,5 N KC1) und eine Trans­portzahl t_ von 0,75 bis 0,85 aufweisen. Ionenaustauschermembranen mit den genannten Eigenschaften sind für andere Einsatzgebiete handelsüblich. Nach einer bevorzugten Ausführungsform besteht der Katholyt aus einer sauren Alkalimetallchloridlösung, die mittels einer pH-Meßeinrichtung, welche mit einer Salzsäuredosierpumpe gekoppelt ist, in einem pH-Bereich von 0,5 bis 6,5 kontinuierlich konstant ge­halten wird. Fernerhin sollte die Anordnung so getroffen sein, daß die gebeizten nichteisenhaltigen Metalle durch die Ionenaustauscher­membran in die Katholytlösung überführbar sind, aus der sie durch periodische pH-Wert-Erhöhung, Ausfällung und Abfiltration selbst­tätig entfernbar sind.There are also several options for further configuration. The carrier film material is preferably fluorinated. According to a preferred embodiment, the applied exchange resin consists of vinyl pyridinium halide, in particular bromide. Such ion exchange membranes are particularly suitable if they have a specific electrical resistance of at most 7 ohms / cm 2, a selectivity of 65 to 90% (0.5 N KC1) and a transport number t_ of 0.75 to 0.85. Ion exchange membranes with the properties mentioned are commercially available for other areas of application. According to a preferred embodiment, the catholyte consists of an acidic alkali metal chloride solution which is kept constant in a pH range from 0.5 to 6.5 by means of a pH measuring device which is coupled to a hydrochloric acid metering pump. Furthermore, the arrangement should be such that the pickled non-ferrous metals can be transferred through the ion exchange membrane into the catholyte solution, from which they can be automatically removed by periodic pH increases, precipitation and filtration.

Die Erfindung beruht der Erkenntnis, daß die genannten Ionenaustauschermembranen für die Regenerierung zumin­dest teilweise verbrauchter Lösungen praktisch ideal sind. Unkontrollierbare Katholyt/Anolyt-Vermischungen sind nicht mehr möglich. Zufolge des niedrigen spezifischen elektrischen Wider­standes der Ionenaustauschermembran ist ein geringer Spannungsab­fall und somit Energieverbrauch gewährleistet. Entsorgungstech­nisch problematische Abfälle fallen nicht an. Gelöste, nichteisen­haltige Metallionen werden durch die Membran in den Katholyten überführt, aus dem sie problemlos entfernt werden, die regenerierte Lösung wird insoweit nicht aufgesättigt.The invention is based on the knowledge that the ion exchange membranes mentioned are practically ideal for the regeneration of at least partially used solutions. Uncontrollable catholyte / anolyte mixtures are no longer possible. Due to the low specific electrical resistance of the ion exchange membrane, a low voltage drop and thus energy consumption is guaranteed. There is no problematic waste disposal. Dissolved, non-ferrous metal ions are transferred through the membrane into the catholyte, from which they are easily removed, the regenerated In this respect, the solution is not saturated.

Im folgenden wird die Vorrichtung anhand einer ein Ausführungsbei­spiel darstellenden Schemazeichnung erläutert.In the following, the device is explained on the basis of a schematic drawing illustrating an exemplary embodiment.

Die in der einzigen Figur in Aufsicht dargestellte Vorrichtung dient zum kontinuierlichen elektrolytischen Regenerieren einer zu­mindest teilsweise verbrauchten Ätzlösung in Form einer zum Ätzen von Metallen eingesetzten Eisen-(III)-chlorid-Lösung und besteht in ihrem grundsätzlichen Aufbau aus einem Elektrolysezellenbehälter 1. In diesem Behälter 1 sind drei Anolytzellen 2 eingesetzt, in denen Anoden 3 aus kunststoffimprägniertem Graphit angebracht sind. Zwi­schen den Anolytzellen 2 befinden sich in einem gemeinsamen Katholyt­raum 4 Kathoden 5. In den Wänden der Anolytzellen 2 sind Ionenaus­tauschermembranen 6 so angebracht, daß sie den Anolytraum 7 vom Katholytraum 4 absolut dicht trennen. Diese Ionenaustauschermem­branen 6 bestehen jeweils aus einer etwa 0,2 mm starken Polytetra­fluoräthylenfolie mit aufgepfropftem quaternarisierten Vinylpyridinium­bromid. Der Katholytraum 4 ist mit einer Alkalimetallchloridlösung gefüllt, die über die Leitungen 8 in einem Kreislauf mittels einer Pumpe 11 geführt ist. Der Pumpe 11 nachgeschaltet ist ein Wärme­tauscher 12, zum ggf. erforderlichen Kühlen der Lösung. Der pH-Wert der Katholytlösung wird mittels einer Meßeinrichtung 14, die selbst­tätig eine Salzsäuredosierpumpe 13 ansteuert, kontinuierlich geregelt und somit auf einem gewünschten Niveau gehalten. Der hinter die Meßeinrichtung 14 geschaltete Filter 15 dient der Trennung der aus­gefällten Metallhydroxide. In die Anolyträume 7 wird über Zuleitungen 9 die zu regenerierende Lösung gleichmäßig eingeführt. Nach der anodischen Oxidation des Eisen(II) zu Eisen(III) wird das aufbe­reitete Ätzmedium über eine Rückführleitung 10 in eine nicht dar­gestellte Beizmaschine oder einen Lagertank rückgeführt.The device shown in top view in the single figure serves for the continuous electrolytic regeneration of an at least partially used etching solution in the form of an iron (III) chloride solution used for etching metals and consists in its basic structure of an electrolytic cell container 1. In this container 1, three anolyte cells 2 are used, in which anodes 3 made of plastic-impregnated graphite are attached. Between the anolyte cells 2 there are 4 cathodes 5 in a common catholyte space. Ion exchange membranes 6 are attached in the walls of the anolyte cells 2 in such a way that they separate the anolyte space 7 from the catholyte space 4 in an absolutely tight manner. These ion exchange membranes 6 each consist of an approximately 0.2 mm thick polytetrafluoroethylene film with grafted quaternary vinylpyridinium bromide. The catholyte space 4 is filled with an alkali metal chloride solution, which is guided in a circuit by means of a pump 11 via the lines 8. The pump 11 is followed by a heat exchanger 12 for cooling the solution, if necessary. The pH of the catholyte solution is continuously regulated by means of a measuring device 14, which automatically controls a hydrochloric acid metering pump 13, and is thus kept at a desired level. The filter 15 connected behind the measuring device 14 serves to separate the precipitated metal hydroxides. The solution to be regenerated is introduced uniformly into the anolyte spaces 7 via feed lines 9. After the anodic oxidation of iron (II) to iron (III), the processed etching medium is returned via a return line 10 to a pickling machine (not shown) or a storage tank.

Claims (10)

1. Verfahren zum Beizen von Halbzeugen, dadurch ge­kennzeichnet, daß man eine saure Eisen(III)-chlorid-­Lösung verwendet.1. A process for pickling semi-finished products, characterized in that an acidic iron (III) chloride solution is used. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Eisen(III)-chlorid-Lösung durch Zugabe von Salzsäure auf eine HCl-Konzentration von 0,5 bis 2 mol/dm³ Lösung, insbesondere 1,0 mol/dm³ Lösung eingestellt ist.2. The method according to claim 1, characterized in that the iron (III) chloride solution is adjusted by adding hydrochloric acid to an HCl concentration of 0.5 to 2 mol / dm³ solution, in particular 1.0 mol / dm³ solution . 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Eisen(III)-chlorid-Lösung bis 45 Gew.-%, insbesondere 40 Gew.-% FeCl₃ enthält.3. The method according to claim 1 or 2, characterized in that the iron (III) chloride solution contains up to 45 wt .-%, in particular 40 wt .-% FeCl₃. 4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekenn­zeichnet, daß die Eisen(III)-chlorid-Lösung zumindest teilweise durch elektrolytische oder chemische Regeneration zumindest teilweise ver­brauchter Eisen(III)-chlorid-Beizlösung erhalten worden ist.4. The method according to any one of claims 1 to 3, characterized in that the iron (III) chloride solution has been obtained at least partially by electrolytic or chemical regeneration at least partially used iron (III) chloride pickling solution. 5. Vorrichtung zum kontinuierlichen elektrolytischen Regenerieren einer zumindest teilweise verbrauchten, insbesondere einer zum Beizen von Metallen nach Anspruch 4 eingesetzten, sauren Eisen(III)-chlorid-­Lösung, bestehend aus einem Elektrolysezellenbehälter, der mit Hilfe wenigstens einer Ionenaustauschermembran in einen mit einem Katholyten gefüllten Katholytraum mit wenigstens einer Kathode und in wenigstens einen mit der Eisen(III)-chlorid-Lösung als Anolyten gefüllten Anolytraum mit jeweils einer Anode, einer kontinuierlich zumindest teilweise verbrauchte Lösung zuführenden Zuleitung und einer kontinurierlich regenerierte Lösung abführenden Rückführleitung unterteilt ist, dadurch gekennzeichnet, daß die Ionenaustauscher­membran (6) jeweils aus einer 0,05 bis 0,50 mm starken Trägerfolie aus Polyester, Polyäthylen oder Polyvinylchlorid mit aufgebrachtem Austauscherharz besteht.5. Device for the continuous electrolytic regeneration of an at least partially used, in particular one used for pickling metals according to claim 4, acidic iron (III) chloride solution, consisting of an electrolytic cell container, which is filled with at least one ion exchange membrane in a filled with a catholyte The catholyte compartment is divided into at least one cathode and is divided into at least one anolyte compartment filled with the iron (III) chloride solution as the anolyte, each with an anode, a supply line continuously supplying at least partially used solution and a return line that continuously regenerates the solution, characterized in that the ion exchange membrane (6) consists in each case of a 0.05 to 0.50 mm thick carrier film made of polyester, polyethylene or polyvinyl chloride with an applied exchange resin. 6. Vorrichtung nach Anspruch 5, dadurch gekennzeichnet, daß das Trägerfolienmaterial fluorisiert ist.6. The device according to claim 5, characterized in that the carrier film material is fluorinated. 7. Vorrichtung nach Anspruch 5 oder 6, dadurch gekennzeichnet, daß das aufgebrachte Austauscherharz aus Vinylpyridiniumhalogenid be­steht.7. Apparatus according to claim 5 or 6, characterized in that the applied exchange resin consists of vinyl pyridinium halide. 8. Vorrichtung nach einem der Ansprüche 5 bis 7, dadurch gekenn­zeichnet, daß die Ionenaustauschermembran (6) einen spezifischen elektrischen Widerstand von höchstens 7 Ohm/cm², eine Selektivität von 65 bis 90 % (0,5 n KCl) und eine Transportzahl t_ von 0,75 bis 0,85 aufweist.8. Device according to one of claims 5 to 7, characterized in that the ion exchange membrane (6) has a specific electrical resistance of at most 7 ohms / cm², a selectivity of 65 to 90% (0.5 n KCl) and a transport number t_ of 0.75 to 0.85. 9. Vorrichtung nach einem der Ansprüche 5 bis 8, dadurch gekenn­zeichnet, daß der Katholyt aus einer sauren Alkalimetallchloridlösung besteht, die mittels einer pH-Meßeinrichtung (14), welche mit einer Salzsäuredosierpumpe (13) gekoppelt ist, in einem pH-Bereich von 0,5 bis 6,5 kontinuierlich konstant gehalten wird.9. Device according to one of claims 5 to 8, characterized in that the catholyte consists of an acidic alkali metal chloride solution, which by means of a pH measuring device (14) which is coupled to a hydrochloric acid metering pump (13) in a pH range of 0 , 5 to 6.5 is kept constant constantly. 10. Vorrichtung nach einem der Ansprüche 5 bis 9, dadurch gekenn­zeichnet, daß die gebeizten, nichteisenhaltigen Metalle durch die Ionenaustauschermembran (6) in die Katholytlösung überführbar sind, aus der sie durch periodische pH-Wert-Erhöhung, Ausfällung und Abfiltration selbsttätig entfernbar sind.10. Device according to one of claims 5 to 9, characterized in that the pickled, non-ferrous metals can be transferred through the ion exchange membrane (6) into the catholyte solution, from which they can be automatically removed by periodic increase in pH, precipitation and filtration.
EP19880109498 1987-06-12 1988-06-15 Pickling of semi-finished products Withdrawn EP0346510A1 (en)

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DE19873719604 DE3719604A1 (en) 1987-06-12 1987-06-12 Pickling of semifinished articles
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0506000A2 (en) * 1991-03-29 1992-09-30 Scientific Impex Establishment Apparatus for chemical treatment of metal
EP0517234A2 (en) * 1991-06-07 1992-12-09 Nippon Paint Co., Ltd. Method of regenerating aluminium surface cleaning agent
FR2839984A1 (en) * 2002-05-23 2003-11-28 Afelec Treatment of a spent pickling bath in an electrolysis cell with a cathodic compartment and an anodic compartment separated by an anion exchange membrane permeable to chloride ions and impermeable to iron ions

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE637287C (en) * 1935-01-20 1936-10-24 Georg Agde Dr Process for refreshing pickling solutions containing trivalent iron salts
DE2736255A1 (en) * 1977-08-11 1979-03-01 Beugin Procedes Sa Pickling bath for steels - contg. acid and ferric chloride
DE3801018A1 (en) * 1987-01-19 1988-07-28 Borsodi Vegyi Komb Process for removing scale and oxides from metals, metal alloys, in particular alloyed steels, highly alloyed steels and carbon steels, by means of a pickling bath containing iron (III) ions

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE637287C (en) * 1935-01-20 1936-10-24 Georg Agde Dr Process for refreshing pickling solutions containing trivalent iron salts
DE2736255A1 (en) * 1977-08-11 1979-03-01 Beugin Procedes Sa Pickling bath for steels - contg. acid and ferric chloride
DE3801018A1 (en) * 1987-01-19 1988-07-28 Borsodi Vegyi Komb Process for removing scale and oxides from metals, metal alloys, in particular alloyed steels, highly alloyed steels and carbon steels, by means of a pickling bath containing iron (III) ions

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0506000A2 (en) * 1991-03-29 1992-09-30 Scientific Impex Establishment Apparatus for chemical treatment of metal
EP0506000A3 (en) * 1991-03-29 1993-02-24 Scientific Impex Establishment Apparatus for chemical treatment of metal
EP0517234A2 (en) * 1991-06-07 1992-12-09 Nippon Paint Co., Ltd. Method of regenerating aluminium surface cleaning agent
EP0517234A3 (en) * 1991-06-07 1993-12-22 Nippon Paint Co Ltd Method of regenerating aluminium surface cleaning agent
FR2839984A1 (en) * 2002-05-23 2003-11-28 Afelec Treatment of a spent pickling bath in an electrolysis cell with a cathodic compartment and an anodic compartment separated by an anion exchange membrane permeable to chloride ions and impermeable to iron ions

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