EP0447008A1 - Verwendung von Brünierbadschlamm - Google Patents

Verwendung von Brünierbadschlamm Download PDF

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Publication number
EP0447008A1
EP0447008A1 EP91250039A EP91250039A EP0447008A1 EP 0447008 A1 EP0447008 A1 EP 0447008A1 EP 91250039 A EP91250039 A EP 91250039A EP 91250039 A EP91250039 A EP 91250039A EP 0447008 A1 EP0447008 A1 EP 0447008A1
Authority
EP
European Patent Office
Prior art keywords
bath
sludge
degreasing
blackening
use according
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Withdrawn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
EP91250039A
Other languages
German (de)
English (en)
French (fr)
Inventor
Jürgen Kader
Peter M. Zwez
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.)
ZWEZ CHEMIE GmbH
Original Assignee
ZWEZ CHEMIE GmbH
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 ZWEZ CHEMIE GmbH filed Critical ZWEZ CHEMIE GmbH
Publication of EP0447008A1 publication Critical patent/EP0447008A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
    • C23C22/62—Treatment of iron or alloys based thereon
    • 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
    • C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
    • C23G1/19—Iron or steel

Definitions

  • the invention relates to the use of blackening sludge and preferably processed blackening sludge for the production or addition of alkaline degreasing and cleaning solutions for metals, in particular iron materials.
  • oxidizing agents which primarily contain sodium hydroxide solution and sodium nitrite and / or sodium nitrate.
  • the bronzing baths can contain conventional additives such as additives that improve the layer formation (e.g. sulfur compounds, phosphates, fluorides, sulfates and chlorides) and surfactants as so-called splash protection or spray protection.
  • the application concentrations of the blackening solutions are defined via the boiling point and are between 110 and 150 ° C.
  • browning requires a workpiece surface that is as 100% hydrophilic and absolutely clean as possible, the actual browning process is usually preceded by degreasing and usually also pickling, including intermediate rinsing stages.
  • Alkaline solutions are used for degreasing.
  • One uses one for the subsequent pickling dilute mineral acids or their mixtures, which can also contain inhibitors (organic substances that reduce the pickling attack of acids on metals) and surfactants (e.g. in the form of so-called pickling degreasers).
  • oiling is carried out to improve the corrosion protection effect and the appearance of the treated workpiece surface.
  • the last rinse before oiling may take place at an elevated temperature.
  • additions of substances or substance mixtures can be added, which have a solvent and / or neutralizing effect on blackening salt residues.
  • water-soluble corrosion protection oils at 60 to 95 ° C, oils heated to 105 to 120 ° C or solvent-based corrosion protection agents based on chlorinated hydrocarbons or white spirits (possibly with a dewatering effect) are used.
  • the first four stations can be omitted in exceptional cases, e.g. after thorough blasting (e.g. sandblasting).
  • the blackening is sometimes carried out in two successive baths, ie workpieces are treated with the same pre- and post-treatment two bronzing baths with different boiling points and thus different bath concentrations immersed.
  • An important aspect in the operation of blackening systems is the disposal of the active baths degreasing, pickling, browning and oiling after reaching the respective suitability limit and the rinsing water accumulating in the different rinsing stations.
  • the flushing water quantities are usually reduced by expanding the flushing stations between the active baths by 1 to 2 pools each, which are connected in cascade form.
  • the amount of rinsing water is reduced by a factor of 10 for each rinsing station while maintaining the rinsing quality.
  • each active bath can be combined in the process sequence with the subsequent rinsing stations to form a recycling circuit, i.e. the evaporation losses of the active baths are compensated for with the water of the first sink in the following rinsing bath arrangement, while the water loss in the first sink is compensated for with water from the second sink, etc. If water is required in the sinks, fresh water is added from the mains. This return of the rinsing water into the respective active bath enables such a blackening system to be operated exclusively with standing sinks, so that no rinsing water has to be disposed of and there are savings of around 20 to 30% in the use of chemicals.
  • the active baths are disposed of during degreasing and pickling in the form of concentrate removal and can be carried out by waste disposal companies.
  • the degreasing solution is usually disposed of every 2 to 4 weeks and the pickling solution every 4 to 8 weeks.
  • procedure B is the lower volume of sludge to be deposited as hazardous waste.
  • the disadvantage is that it is a multi-stage process, in which there is a considerable environmental hazard when dissolving with acid through the formation of nitrous gases (extremely toxic), which requires complex protective measures and a very complicated exhaust air cleaning.
  • nitrous gases extremely toxic
  • the invention was therefore based on the object of simplifying the disposal of the blackening sludge or even making it completely unnecessary by using the blacking bath sludge in a meaningful manner.
  • blackening sludge and preferably processed blackening sludge for the production or supplementation of alkaline degreasing and cleaning solutions for metals, in particular iron materials, is proposed according to the invention.
  • black bath sludge and in particular black bath sludge prepared by elution, can be digested in the alkaline range in such a way that an aqueous alkaline solution is formed which has properties which make it suitable for use as a degreasing and cleaning solution, e.g. in a blackening process.
  • the sludge obtained in the blackening bath is preferably first processed. To do this, it is collected in a suitable vessel and allowed to settle. The clear solution above is returned to the bronzing bath. Water is then added to the slurry and the slurry thus obtained is stirred, the duration of the stirring depending on the amount of slurry to be treated. With average amounts of sludge, a stirring time of about 2 to 3 hours has been found to be sufficient, which is then followed by prolonged settling, preferably over a period of 1 to 2 days.
  • the quantitative ratio (volume) of added water to sludge depends on the nature of the respective blackening sludge and in particular its solids content and is generally 0.5: 1 to 5: 1 and preferably 1: 1 to 2: 1. The after Allow supernatant aqueous solution to be returned to the bronzing bath.
  • the settled sludge (so-called conditioned sludge) obtained in this way is used for the production and supplementation of alkaline degreasing and cleaning solutions. It is used particularly advantageously in the degreasing bath usually present in the blackening system. This can be done by adding the sludge in portions to the degreasing bath depending on its consumption. In order to improve or optimize the cleaning and degreasing effect of the degreasing bath supplemented with reprocessed bronzing bath sludge, it is advisable to supplement the degreasing bath not only with blackening bath sludge but also with surfactants and other customary auxiliaries. These are essentially the following substances.
  • surfactants are very important for the degreasing effect. Therefore, the combination of bronzing sludge with surfactants is the most significant improvement. All surfactants customary for these purposes are suitable, although surfactants which differ from the surfactants normally used by a higher cloud point are preferred because of the high neutral salt content of the blackening sludge. Anionic and nonionic surfactants are preferably used.
  • the cloud point of the surfactants used or of the preferred surfactant mixtures should be above 60 ° C. and preferably above 98 ° C. under operating conditions based on DIN 53917.
  • Suitable nonionic surfactants are, for example, ethoxylated fatty alcohols, oxo alcohols (for example Lutensol-ON types) or terminally blocked oxethylates, suitable anionic surfactants for example alkylarylsulfonates or other anionic surfactants with comparable characteristics (for example Lutensit-A types).
  • blackening sludge generally also contains certain proportions of substances which are insoluble in water and dilute alkalis, it is advantageous if dispersing agents are added to the degreasing bath.
  • Dispersing aids of this type are usually used in alkaline scouring degreasers, such as are used in burnishing plants, and are known to the person skilled in the art.
  • Particularly suitable are native or fully or partially synthetic dispersants on an anionic basis, such as lignin sulfonates, di- and polycarboxylic acids and their derivatives, i.e. Copolymers, polyesters, etc., and aromatic or aliphatic sulfonic acid derivatives.
  • the usual additional amounts for recycling blackening sludge are often not sufficient to keep the insoluble substances contained in the blackening sludge plus the contaminants introduced by the workpieces distributed in the degreasing bath. It is therefore preferable to use higher amounts of dispersant than normal degreasing baths. Based on the degreasing bath, the dispersant concentration should therefore be at least 0.1% by weight and preferably 1 to 5% by weight. If the surfactants and the other auxiliaries are added to the degreasing bath as a mixture, this should contain at least 5% of a dispersant active in the pH range of over 11.
  • complexing agents are often added to the degreasing bath.
  • gluconic acid and gluconic acid salts are also preferred according to the invention, with gluconic acid and gluconic acid salts, heptonates, citrates and compounds from the group consisting of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), N- (hydroxyethyl) ethylenediaminetriacetic acid (HEDTA) and phosphonic acids as salts, in particular alkali salts, or in the form of the free acids are examples of suitable complexing agents. Since the bronzing bath sludge already ensures a high salt content, the use of the complexing agents is according to the invention preferred in the acid form and especially of gluconic acid.
  • the composition of the bluing bath sludge is of course directly related to the composition of the bluing bath.
  • the blackening sludge obtained as a salt-like residue consists predominantly of caustic soda, soda and water.
  • the rest are the usual additives for bronzing salts such as phosphates, oxidizing agents such as nitrite and / or nitrate, chlorides, sulfates and traces of metals in the bronzing material (including manganese, zinc, nickel, copper and iron).
  • the oxidizing agents contained in the blackening sludge (usually alkali metal nitrates and / or nitrites) can lead to environmental problems as well as to the operating personnel of the blackening system.
  • blackening systems often include pickling baths, so that the spreading of degreasing solution containing blackening bath sludge, which is always to be expected, cannot lead to the formation of nitrous gases.
  • nitrite-interfering substances e.g. sulfamic acid, ascorbic acid, hydroxylamine, H2O2, chlorate and ammonium polyphosphate
  • a nitrite disorder can also be caused by mixing the degreasing solution with air.
  • urea is stable for a certain time in alkaline solutions, so that the addition of urea to the degreasing bath represents a safety factor against the development of nitrous gases.
  • amidosulfonic acid whose use in alkaline degreasing products is not yet known, offers further safety. It has been found that an amount of the order of at least 110% and preferably at least 150% of the nitrite-interfering substance (based on the sodium nitrite content of the blackening sludge) is necessary in order to prevent the formation of nitrous gases if no other nitrite-interfering additive is used.
  • the surfactants and auxiliaries to be added to the degreasing bath in combination with the blackening sludge are preferably used as a premix, so that each additive does not have to be added individually.
  • the composition of this auxiliary mixture should be adapted to the respective requirements for the degreasing bath and the blackening sludge used, e.g. a nitrite-free bronzing salt in the resulting sludge may contain less, but at least something, nitrite originating from reduced nitrate. In this case, excessive additions of nitrite-interfering substances would only lead to unnecessary salting.
  • the conditioned bronzing bath sludge is not fed directly to the degreasing bath, but is digested to produce a degreasing and cleaning solution.
  • water fresh water or rinsing water from a rinsing stage following the degreasing
  • the desired surfactants and other auxiliaries preferably in the form of a mixture
  • the solution thus obtained is then the conditioned bronzing sludge at room temperature or, if appropriate, with heating with stirring added.
  • the stirring is continued for some time, so that a solution is generally formed, the concentration of which is controlled and controlled on the basis of the density.
  • the setpoint at 20 ° C should be in the range of 7 to 10 ° Bé (1020 to 1200 kg / m3). With a value of less than 7 ° Bé (1020 kg / m3) a further addition of sludge in partial quantities (with intermediate measurements) is possible and necessary.
  • This solution can then be used immediately as a degreasing and cleaning solution. For example, it can replace the products previously used for boiling degreasing in burnishing systems.
  • the proportions of the so-called builder substances in the usual alkaline cleaners / decoction degreasing can be varied within a wide range without a significant change in the intended effect, the system-related fluctuations in the composition of the bronzing bath sludge (respective application situation and composition of the used) Blackening salt) has no adverse effect.
  • the inventive separation of the inorganic chemical framework, i.e. the builder (bronzing sludge) of the degreasing components (additives such as surfactants and auxiliaries) can also be easily adapted to the degreasing effect to the specific needs of the individual case.
  • Regeneration of the degreasing baths to maintain the cleaning and degreasing effect is often more effective if the bath components are not used in the original batch ratio, which is essential for conventional ready-mixed degreasing products.
  • the invention here offers the possibility of adjusting the regeneration particularly to the surfactant mixture which is decisive for the degreasing effect.
  • a degreasing bath customary for blackening systems was produced.
  • a powder mixture with the following composition was used for this: 30.0 kg caustic soda 30.0 kg soda 10.0 kg trisodium phosphate x 12 H2O 20.0 kg sodium chloride / sodium sulfate 10.0 kg of surfactants (anionic and nonionic), dispersant.
  • This powder mixture was dissolved in water in a concentration of 8% by weight, so that a degreasing bath with the following active ingredient contents (per 100 l of water) resulted: 2.8 kg caustic soda 2.8 kg soda 0.8 kg trisodium phosphate x 12 H2O 1.6 kg sodium chloride / sodium sulfate 0.8 kg surfactants (anionic and non-ionic), dispersant.
  • a degreasing bath according to the invention was produced using blackening sludge.
  • the bath sludge collected from various burnishing plants had the following average composition: 28.0 kg caustic soda 40.0 kg soda 5.0 kg trisodium phosphate 1.0 kg sodium chloride / sodium sulfate 5.0 kg sodium nitrite, sodium nitrate ⁇ 0.1 kg surfactants (anionic) 20.0 kg of water.

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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)
EP91250039A 1990-02-16 1991-02-13 Verwendung von Brünierbadschlamm Withdrawn EP0447008A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19904004914 DE4004914A1 (de) 1990-02-16 1990-02-16 Verwendung von bruenierbadschlamm
DE4004914 1990-02-16

Publications (1)

Publication Number Publication Date
EP0447008A1 true EP0447008A1 (de) 1991-09-18

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EP91250039A Withdrawn EP0447008A1 (de) 1990-02-16 1991-02-13 Verwendung von Brünierbadschlamm

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EP (1) EP0447008A1 (enrdf_load_stackoverflow)
DE (1) DE4004914A1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1284309A1 (de) * 2001-07-20 2003-02-19 Zwez Chemie Gmbh Komponenten und Verfahren zur Herstellung und Regeneration eines Brünierbades

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012019731A1 (de) * 2012-10-09 2014-04-10 Overlack GmbH Verfahren zur Beschichtung von Metalloberflächen mit einer Konversionsschicht und Vorrichtung zur Durchführung des Verfahrens

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB538210A (en) * 1940-03-02 1941-07-24 Heatbath Corp Improvements in or relating to the imparting of color finish to iron and steel articles
US2309745A (en) * 1940-10-14 1943-02-02 American Steel & Wire Co Method of processing wire
US3085035A (en) * 1960-06-20 1963-04-09 Gen Motors Corp Composition and method for cleaning and blackening metal dies
US3447974A (en) * 1966-03-14 1969-06-03 Enthone Composition and method for blackening metal article surfaces

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1914759A1 (de) * 1969-03-22 1970-10-01 Dettner Dr Heinz W Heisse alkalische Baeder
DE3636390A1 (de) * 1986-10-25 1988-04-28 Metallgesellschaft Ag Verfahren zur erzeugung von phosphatueberzuegen auf metallen

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB538210A (en) * 1940-03-02 1941-07-24 Heatbath Corp Improvements in or relating to the imparting of color finish to iron and steel articles
US2309745A (en) * 1940-10-14 1943-02-02 American Steel & Wire Co Method of processing wire
US3085035A (en) * 1960-06-20 1963-04-09 Gen Motors Corp Composition and method for cleaning and blackening metal dies
US3447974A (en) * 1966-03-14 1969-06-03 Enthone Composition and method for blackening metal article surfaces

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1284309A1 (de) * 2001-07-20 2003-02-19 Zwez Chemie Gmbh Komponenten und Verfahren zur Herstellung und Regeneration eines Brünierbades

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Publication number Publication date
DE4004914C2 (enrdf_load_stackoverflow) 1993-03-25
DE4004914A1 (de) 1991-08-22

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