EP0838539A1 - Procédé de prétraitement de pièces métalliques - Google Patents

Procédé de prétraitement de pièces métalliques Download PDF

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Publication number
EP0838539A1
EP0838539A1 EP96117025A EP96117025A EP0838539A1 EP 0838539 A1 EP0838539 A1 EP 0838539A1 EP 96117025 A EP96117025 A EP 96117025A EP 96117025 A EP96117025 A EP 96117025A EP 0838539 A1 EP0838539 A1 EP 0838539A1
Authority
EP
European Patent Office
Prior art keywords
acid
degreasing
bath
phase
pickling
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.)
Withdrawn
Application number
EP96117025A
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German (de)
English (en)
Inventor
Heinz Külker
Johann Schiller
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.)
Rietbergwerke Entwicklungs- und Vertriebsgesellschaft mbH
Original Assignee
Rietbergwerke Entwicklungs- und Vertriebsgesellschaft mbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Rietbergwerke Entwicklungs- und Vertriebsgesellschaft mbH filed Critical Rietbergwerke Entwicklungs- und Vertriebsgesellschaft mbH
Priority to EP96117025A priority Critical patent/EP0838539A1/fr
Publication of EP0838539A1 publication Critical patent/EP0838539A1/fr
Withdrawn legal-status Critical Current

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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
    • C23G1/36—Regeneration of waste pickling liquors

Definitions

  • the invention relates to a method for pretreating metal parts which degreases the metal parts in a degreasing bath and then in one Pickling bath can be pickled with acid, and an acidic one for degreasing Degreasing agent is used, the auxiliary agent that promotes degreasing (Surfactants) contains.
  • Such pretreatment is particularly important for corrosion protection processes provided by metal coating, for example before hot-dip galvanizing Metal parts.
  • the metal surfaces become sticky Greases and oils such as rolling oils, drawing oils and the like from previous ones Processing steps exempted (in the following, the term "fats” as Generic term for fats and oils are used).
  • the subsequent pickling usually takes place gradually in several pickling baths and serves primarily for the removal of species-specific impurities, such as rust or Tinder.
  • the metal parts are made without prior Degreasing placed in a pickling bath for dezincification so that the faulty Galvanizing layers are solved before the new galvanizing. After pickling the metal parts go through a rinse bath and a flux bath before they be galvanized in the zinc kettle. The rinsing should, in particular, result from the washing of iron in the flux bath and further reduced in the zinc kettle will.
  • the one with specific light Fat-enriched surface layer continuously or at intervals skim off and the demulsified fats, for example in a coalescence separator to separate.
  • the separated fats are disposed of, while the rest of the liquid is returned to the degreasing bath becomes.
  • alkaline degreasing agent in conventional pretreatment processes either alkaline or acidic aqueous solutions are used, the appropriate ones Auxiliaries, primarily surfactants, are added which Promote and control emulsification of fats.
  • alkaline degreasers the disadvantage that they neutralize the acidic pickling solutions when they are in the pickling bath are carried over. When using alkaline degreaser therefore a rinse is generally required after the degreasing stage.
  • the object of the invention is a method for pretreating metal parts specify that on a large industrial scale stable and economically applicable is and allows the amount of degreasing Reduce waste.
  • the one in phase separation Acid obtained, contaminated with metals does not need to be disposed of to be, but can be used in the pickling bath and thus serves to compensate for the evaporation and carryover losses in the pickling bath. Since this acid is not contaminated with additives or fats, it does not interfere with the pickling process. The exposure to metal ions is also harmless, since the pickling solution has a comparatively high metal content anyway having.
  • the used degreasing agent practically completely recycled, so that the at The amount of waste generated is reduced to the separated fats.
  • the phase separation in the used degreasing agent is preferably carried out by heating in a separation container so that in the separation container a layered liquid is created.
  • the fatty upper liquid layer can then with the help of known scoops or skimmers subtracted from.
  • metal content and chemical composition of the degreasing agent it can happen that in the The separation container initially only forms a two-phase liquid.
  • the top phase then consists of a mixture of fats and adjuvants bound to them as well as unbound auxiliaries, while the lower phase made of metal There is acid.
  • the upper phase can then be added by Fresh acid are further broken down so that an upper phase is obtained, which only consists of fats and auxiliary substances bound to them and again skimmed or skimmed with the help of a scoop can.
  • the remaining liquid then consists essentially of metal-free Acid and auxiliary substances and can be used as a complete degreasing agent in the degreasing bath can be returned. Used and possibly towed out Auxiliaries, e.g. Surfactants, are supplemented by adding.
  • the galvanizing material is transferred from a degreasing bath 10 one or more pickling baths 12 transferred into a rinsing bath 14.
  • the degreasing bath 10 contains a degreasing agent in the form of an acid mixture Excipients and other excipients and is at a temperature of about Kept at 25 to 30 ° C. Those adhering to the surface of the galvanizing material Fats are released and accumulate in the degreasing agent. Due to the acidic environment, metals are also in a certain degree the degreasing agent dissolved. Since incorrectly galvanized parts are usually not degreased the dissolved metal ions are mainly for iron.
  • the galvanized material cleaned from fats is then pickled in the pickling bath 12.
  • the pickling solution is an acid mixture with hydrochloric acid as The main component that causes contaminants such as rust or scale from the Surface of the galvanized material to be removed. This also goes essentially Iron in solution. However, since incorrectly galvanized parts are also pickled, The pickling solution also contains a certain amount of zinc ions.
  • the galvanizing material passes from the pickling bath 12 into the rinsing bath 14, which initially contains pure water. However, since the galvanizing material is wetted with pickling solution acid and metal ions are also to a certain extent in the rinse water registered. Overall, this results from carry-over Transport of water, acid and metal ions from the degreasing bath 10 over the pickling bath 12 into the rinsing bath 14. Furthermore, it occurs in all three baths evaporation losses that are replaced from the rinsing bath.
  • a phase separation stage 16 is assigned to the degreasing bath 10. So yourself the fats and dissolved metals are not excessive in the degreasing agent concentrate, becomes a certain amount at certain time intervals or batch of degreasing agent derived from the degreasing bath 10 and transferred to the phase separation stage. There by heating the degreasing agent brought about phase separation at about 40 to 70 ° C, so that you ultimately get three different phases, as related below is described in more detail with FIG.
  • the specifically lightest Phase consists essentially of the fats and adjuvants bound to them. This phase is separated and, for example, a thermal one Recycling fed. Another phase consists of unbound auxiliary materials and is returned to the degreasing bath 10.
  • phase separation stage 10 essentially consists from acid that is contaminated with metal ions. This from auxiliaries and Fat free acid is added to the acid mixture in the pickling bath 12.
  • pickling bath 12 it occurs due to metal entry from separation stage 16 and all through solution processes on the galvanizing material to a concentration on metal ions (with Fe and Zn as main metals).
  • a membrane electrolysis unit 18 is provided for maintenance of the pickling solution. If the concentration of Zn ions in the pickling bath 12 a certain limit value (for example in the order of 8 g / l) is by membrane electrolysis Zn deposited so that the Zn content in the pickling bath stabilizes becomes, while the Fe content continues to increase. If the Fe content is on one The value of 125 - 130 g / l has risen again in the membrane electrolysis unit 18 carried out a "final treatment".
  • the Zn content reduced to less than 3 g / l, so that an acid with an Fe content of about 125 - 130 g / l, a content of 4 - 6% free acid (HCl) and a Zn content of less than 3 g / l, which is removed as old pickling becomes.
  • This old stain is a valuable material in wastewater treatment usable and therefore not a waste material.
  • the one in this final treatment Acid loss occurring in the pickling bath 12 is caused by the addition of acid replaced from the phase separation stage 16, so that the replenishment of acid in Pickling bath 12 is significantly reduced.
  • the rinsing bath 14 is assigned an electrodialysis unit 20, in which the Rinsing bath resulting water-acid mixture in pure water and metal contaminated Acid is broken down.
  • the acid is also returned to the pickling bath 12 and replaces the carry-over and usage losses there.
  • the Water is returned to the rinsing bath 14 so that the acid and metal content there is kept within permissible limits. Because of the procrastination of water that wets the galvanizing material, depending on the extent the evaporation losses to a more or less large excess of water come so that water from the rinsing bath 14 to the pickling bath 12 and / or can be returned to the degreasing bath 10. By suitable control the return of water to the pickling bath 12 and the degreasing bath 10, if necessary with the addition of fresh water, the respectively required Acid concentration set.
  • phase separation process An example of the phase separation process is shown schematically in FIG.
  • the skimmed off from the degreasing bath 10, with fats and metals contaminated degreasing agent is in a coalescer 22 in a lower phase 24 and an upper phase 26 split.
  • the specific lighter upper phase 26 consists of demulsified fats and is with the help a scoop 28 skimmed or skimmed to the surface of the liquid and disposed of or sent for thermal recycling.
  • the lower one Phase 24 essentially consists of the one loaded with metal ions Acid, the auxiliary substances as well as dissolved or finely emulsified fats. In the Normal care of the degreasing agent, this phase 24 is back in the Degreasing container 10 returned.
  • phase 24 is not returned untreated to the degreasing bath, Rather, it is introduced into a separation container 30 and heated, so that there is a further phase separation.
  • a layered liquid of at least two is obtained in this way Phases 32, 34.
  • the lower phase 32 consists essentially of largely free of fat and additives, but still acidic with metal ions is introduced into the pickling bath 12.
  • the upper phase 34 essentially consists from fats and bound and unbound auxiliary substances. This Phase is skimmed off, for example, with the aid of a further scooping device 36 and introduced into a mixing container 38. In the mixing container 38 preheated fresh acid is also added.
  • phase separation described above independent of the normal care of the degreasing agent.
  • the batch is withdrawn from the degreasing bath 10
  • Degreasing agent introduced directly into the separation container 30.

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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)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
EP96117025A 1996-10-23 1996-10-23 Procédé de prétraitement de pièces métalliques Withdrawn EP0838539A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP96117025A EP0838539A1 (fr) 1996-10-23 1996-10-23 Procédé de prétraitement de pièces métalliques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP96117025A EP0838539A1 (fr) 1996-10-23 1996-10-23 Procédé de prétraitement de pièces métalliques

Publications (1)

Publication Number Publication Date
EP0838539A1 true EP0838539A1 (fr) 1998-04-29

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EP96117025A Withdrawn EP0838539A1 (fr) 1996-10-23 1996-10-23 Procédé de prétraitement de pièces métalliques

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10107936A1 (de) * 2001-02-20 2002-09-05 Feuerverzinkung Hannover Gmbh Verfahren zur Aufbereitung von Prozessflüssigkeiten in Feuerverzinkungsanlagen
EP1281791A1 (fr) * 2001-07-31 2003-02-05 Feuerverzinkung Hannover GmbH & Co. KG Procédé de regéneration des baisn de dégraissage
DE10207082B4 (de) * 2002-02-20 2008-05-29 Klaus Klein Verfahren zum abwasser- und abfallfreien Betrieb von sauren Behandlungsbädern

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2529762A (en) * 1946-04-11 1950-11-14 Carnegie Illinois Steel Corp Method and apparatus for continuous cleaning of metal strip
US4148700A (en) * 1976-10-14 1979-04-10 David B. Dean Method for purifying the liquor of a galvanizing process plant after contamination
DE4123827A1 (de) * 1991-07-18 1993-01-21 Duerr Gmbh & Co Verfahren zur aufbereitung einer waessrigen reinigungsfluessigkeit sowie anlage zur durchfuehrung eines solchen verfahrens
DE9401272U1 (de) * 1993-02-17 1994-03-10 Oekologia Beteiligungs-, Handels- und Patentverwertungsgesellschaft m.b.H., Graz Vorrichtung zum Reinigen von Entfettungsmitteln

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2529762A (en) * 1946-04-11 1950-11-14 Carnegie Illinois Steel Corp Method and apparatus for continuous cleaning of metal strip
US4148700A (en) * 1976-10-14 1979-04-10 David B. Dean Method for purifying the liquor of a galvanizing process plant after contamination
DE4123827A1 (de) * 1991-07-18 1993-01-21 Duerr Gmbh & Co Verfahren zur aufbereitung einer waessrigen reinigungsfluessigkeit sowie anlage zur durchfuehrung eines solchen verfahrens
DE9401272U1 (de) * 1993-02-17 1994-03-10 Oekologia Beteiligungs-, Handels- und Patentverwertungsgesellschaft m.b.H., Graz Vorrichtung zum Reinigen von Entfettungsmitteln

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
BRÜCKEN V.: "Stoffkreislaufschliessung bei der Feuerverzinkung", MO METALLOBERFLACHE, vol. 50, no. 6, 1 June 1996 (1996-06-01), MUNCHEN DE, pages 458 - 460, XP002020233 *
BRUECKEN, KUELKER, STIEGLITZ.: "Stoffkreislaufschliessung bei der Feuerverzinkung.", vol. 6, 1996, CARL HANSER VERLAG., MUENCHEN., pages: 458 - 460
QUAB D ET AL: "ENTFETTUNGSBADER KONTINUIERLICH AUFBEREITEN CONTINUOUS PROCESSING OF DEGREASING BATHS", MO METALLOBERFLACHE, vol. 49, no. 8, 1 August 1995 (1995-08-01), pages 568 - 571, XP000522953 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10107936A1 (de) * 2001-02-20 2002-09-05 Feuerverzinkung Hannover Gmbh Verfahren zur Aufbereitung von Prozessflüssigkeiten in Feuerverzinkungsanlagen
DE10107936C2 (de) * 2001-02-20 2002-12-19 Feuerverzinkung Hannover Gmbh Verfahren zur Aufbereitung von Prozessflüssigkeiten in Feuerverzinkungsanlagen
EP1281791A1 (fr) * 2001-07-31 2003-02-05 Feuerverzinkung Hannover GmbH & Co. KG Procédé de regéneration des baisn de dégraissage
DE10207082B4 (de) * 2002-02-20 2008-05-29 Klaus Klein Verfahren zum abwasser- und abfallfreien Betrieb von sauren Behandlungsbädern

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