EP0320798A1 - Procédé pour éliminer les boues des bains de phosphatation et appareil pour ce procédé - Google Patents

Procédé pour éliminer les boues des bains de phosphatation et appareil pour ce procédé Download PDF

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Publication number
EP0320798A1
EP0320798A1 EP88120522A EP88120522A EP0320798A1 EP 0320798 A1 EP0320798 A1 EP 0320798A1 EP 88120522 A EP88120522 A EP 88120522A EP 88120522 A EP88120522 A EP 88120522A EP 0320798 A1 EP0320798 A1 EP 0320798A1
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EP
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Prior art keywords
sludge
solution
chamber
bath
phosphating
Prior art date
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EP88120522A
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German (de)
English (en)
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EP0320798B1 (fr
Inventor
Kurt Hosemann
Karl-Heinz Gottwald
Willi Dr. Wüst
Hubert Dr. Harth
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Gerhard Collardin GmbH
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Gerhard Collardin GmbH
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Priority to AT88120522T priority Critical patent/ATE77663T1/de
Publication of EP0320798A1 publication Critical patent/EP0320798A1/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
    • 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
    • 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
    • C23C22/06—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 aqueous acidic solutions with pH less than 6
    • C23C22/07—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 aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • C23C22/12—Orthophosphates containing zinc cations
    • C23C22/13—Orthophosphates containing zinc cations containing also nitrate or nitrite anions
    • 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
    • C23C22/73—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 characterised by the process
    • 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
    • C23C22/86—Regeneration of coating baths

Definitions

  • the invention relates to a process for desludging phosphating baths and an apparatus for carrying out this process.
  • oxidizing components are usually added to the zinc phosphate solutions used for the application of the phosphate layer, which are intended to accelerate the formation of layers on the metal surfaces.
  • iron is dissolved and kept in solution in the form of Fe (II) ions. This is converted into insoluble iron (III) phosphate by the oxidizing agents in the phosphating bath and such precipitates.
  • the amount of iron (III) phosphate sludge in the phosphating bath increases. Sludge components settle on the metal surfaces to be phosphated and prevent sufficient formation of the phosphate layer.
  • the bath solutions for removing the iron (III) phosphate sludge must either be immobilized and freed from the sludge after it has settled, or they will - depending on the bath size - completely new.
  • phosphating baths usually only have a limited service life. Apart from the fact that the bath cannot be used during the settling phase, a new or partial preparation of the phosphating bath means a considerable expenditure of chemicals. It is also disadvantageous that the amounts of iron phosphate sludge always contain more or less large amounts of zinc phosphate solution. The disposal of the zinc-containing sludge is not only very complex, but also not without problems for ecological reasons.
  • an oxidizing accelerator such as ClO3 ⁇ is added to the phosphating baths in an amount which enables the iron (II) content to be adjusted from 0.05 to 1% by weight.
  • the formation of sludge is not prevented and the problem is not generally solved.
  • DE-OS 33 45 498 proposes to prevent sludge formation in the phosphating bath in a process for the production of phosphate coatings on iron or steel surfaces by branching off a partial volume of the phosphating solution from the bath tank and this solution in a separate device for the precipitation of Oxidizing agents are added to iron phosphate and the iron phosphate sludge is removed by filtration before the solution is returned to the bath tank.
  • chlorate or hydrogen peroxide is used as the oxidizing agent, but air is also regarded as a suitable oxidizing agent, but this process is described as unusable for practical use.
  • the reaction proceeds comparatively slowly, unless one works under increased pressure. This requires a pressure-resistant design of the separate reaction vessel. Such an expenditure on equipment is therefore not economical.
  • the invention relates to a process for desludging phosphating baths by branching off a partial volume of the phosphating solution from the bath tank, adding oxidizing agent to the branched partial volume with oxidizing agent in order to precipitate the iron contained in the solution as iron phosphate and returning the solution freed from iron phosphate sludge to the bath tank below
  • Setting the bath parameters to the desired values which is characterized in that a partial volume of the phosphating solution is fed continuously to a separate device having three open chambers, in the oxidation chamber of which the solution is gassed with a gas containing O2, after which the iron phosphate sludge formed is conditioned in the sludge conditioning chamber and is separated and removed in the sedimentation chamber and the solution depleted of layer-forming components is supplemented with aqueous solutions which adjust the acid ratio enable and the concentrations of components essential for layer formation and then feed the solution back into the phosphating bath.
  • the invention also relates to a device for carrying out the above-mentioned method with separate chambers for the oxidation of the oxidizable bath components, devices for supplying the oxidizing agent and for supplying, removing and moving the solution and for removing the iron phosphate sludge formed, which is characterized in that it follows System parts comprises: an oxidation chamber 11 with inlet connection 12 and a gassing unit 13, a sludge conditioning chamber 15 which communicates with the oxidation chamber 11 through the overflow 14, devices for forcibly guiding the flow direction 16, a sedimentation chamber 19 which communicates with the sludge conditioning chamber 15 through the Overflow 18 is in communicating connection, the sedimentation of the sludge entrained by the flow in a sludge teat 20 with a separate sludge outlet 23 is possible, and several, essentially parallel, for separating the sludge has separating surfaces 24 arranged in the direction of flow.
  • the process according to the invention serves to desludge phosphating baths which work “on the iron side”, that is to say contain relatively weak oxidizing agents as accelerators, which convert only a small amount of the iron detached from the metal surface into the trivalent state and are thus responsible for only a small amount of sludge formation .
  • relatively weak oxidizing agents as accelerators which convert only a small amount of the iron detached from the metal surface into the trivalent state and are thus responsible for only a small amount of sludge formation .
  • the separate device is dimensioned so that the total bath volume is statistically once can pass through the separate device in the course of a day, whereby dissolved iron (II) is oxidized, precipitated and the precipitated iron (III) phosphate sludge can be separated off.
  • This can be achieved in an advantageous manner that the service life of a phosphating bath can be extended as desired and, in particular, it is no longer necessary to discard the phosphating bath after a certain time in which more or less large amounts of sludge impair the quality of the deposited layers must be or the whole bathroom has to be re-prepared because the deposition of zinc-containing layers in the required quality can no longer be guaranteed.
  • the branched-off partial volume of the phosphating solution is fed to the first chamber 11 of a separate device 1 having three open chambers.
  • the first chamber is commonly referred to as an "oxidation chamber" 11.
  • the supply takes place through the supply opening 12 in an amount which is in equilibrium with the cleaned amounts of phosphating solution running off at the outlet opening 22. It is possible according to the invention to adjust the supply of phosphating solution containing iron (II) phosphate to a volume flow of any size, which ensures complete oxidation of the iron contained in the solution and its precipitation as iron (III) phosphate as well as complete separation of the formed ferrous sludge made possible by sedimentation.
  • the phosphating solution is gassed with a gas containing O2.
  • oxidizing agents for oxidizing iron (II) to iron (III) known from the prior art the procedure has the advantage that no expensive chemicals are required to effect the oxidation process.
  • form of the iron (III) phosphate precipitating under the influence of the oxidizing agent is essentially dependent on the nature of the oxidizing agent.
  • "hard" accelerators such as NO2, ClO3 or H2O2 added as an oxidizing agent
  • zinc-iron-phosphate slurries are formed in the form of large-volume flakes which float in the solution and are very difficult to sediment.
  • the gas containing O2 is fed to the oxidation chamber 11 via a gassing unit 13 with a central flow and a porous surface.
  • This gassing unit can, for example, have a tubular basic shape in which the gas containing O2 flows inside the tube and through more or less large openings in the surface penetrates to the outside.
  • a sintered polypropylene hose is used as the gassing unit.
  • the sintered polypropylene tube used as the gassing unit 13 preferably has an average pore size of 0.10 to 5.0 ⁇ m, with polypropylene tubes having an average pore size of 0.12 to 0.30 ⁇ m being used with particular advantage. This is because they have good permeability and guarantee the formation of gas bubbles in the fineness required for the oxidation process.
  • gases from the group O2 air and air enriched with O2 can be used in preferred embodiments of the method.
  • air is particularly preferred for economic reasons because of its easy availability.
  • the gas containing O2 is supplied in an amount such that the amount of elemental oxygen required for the oxidation process takes place in the range from 0.01 to 100 mol / h.
  • the amount of gas supplied is naturally based on the flow rate of the phosphating solution through the device 1 according to the invention.
  • the oxidation process is illustrated by the following reaction equation:
  • the iron oxidized in the course of the listed reaction equation to iron (III) originating from the metal surface to be phosphated reacts with phosphate anions to form insoluble iron (III) phosphate, which is the essential component of the bath sludge.
  • This, together with the phosphating solution, is fed from below to the device for forcibly guiding the flow direction 16, which can be, for example, a so-called deflecting baffle, at a certain distance above the bottom of the oxidation chamber 11, in which the sludge-containing solution rises.
  • the sludge-containing solution leaves the oxidation chamber 11 and is guided downward in the sludge conditioning chamber 15 by the device for the forced guidance of the flow direction 16. It enters the interior of the sludge conditioning chamber 15 at the lower end of the device 16.
  • the resulting iron phosphate sludge is conditioned in the sludge conditioning chamber 15. This is done to make it more sedimentable.
  • the solution with the iron (III) phosphate contained in the sludge conditioning chamber 15 mud stirred.
  • any flake-like precipitate agglomerates into more sedimentable grains.
  • such grains must not exceed an average size which would cause the solution to sink, since otherwise the sludge would sediment to a considerable extent in the sludge conditioning chamber.
  • Another advantageous effect of the stirring process in the sludge conditioning chamber 15 can be seen in the fact that the gaseous oxygen contained in the solution is more or less completely expelled.
  • the stirring speed is preferably set to 100 to 300 rpm.
  • the phosphating solution thus conditioned which contains easily sedimentable sludge grains, now flows through the overflow 18 between the sludge conditioning chamber 15 and the sedimentation chamber 19 again to a device for forced guidance of the flow direction 16, for example a so-called deflection ski kane, which supplies the solution to the bottom of the sedimentation chamber 19.
  • the device 16 mentioned is also mounted at a certain distance from the bottom of the sedimentation chamber 19.
  • the flow volume which was accelerated by the comparatively small volume of the sludge conditioning chamber 15, is slowed down by the significantly larger volume of the sedimentation chamber 19. It is thereby achieved that in the sedimentation chamber the easily sedimentable sludge grains either sediment immediately into the sludge teat 20 or a more or less large piece with the solution is carried up to the separating surfaces 24 of the sedimentation chamber.
  • This construction which is similar to a conventional lamella separator, ensures that a relatively rapid flow of flow takes place in the middle between the separating surfaces 24, while the flow is slowed in the vicinity of the separating surfaces and also enables the sedimentable sludge grains to be deposited and gravity along the Slip partitions down.
  • this preferred embodiment of the method in which the separation surfaces 24 in the sedimentation chamber 19 are flowed from below, it is achieved that almost the entire amount of sludge already sits in the lower separation surface region and is not even carried up near the drain opening 22.
  • the well sedimenting sludge gradually collects in the sludge teat 20 and can be drawn off from the sedimentation chamber 19 via a separate sludge drain 23.
  • the sludge-free solution is then discharged via the overflow edge 21, which can be a conventional serrated strip, for example 22 fed and removed by this from the inventive device for desludging phosphating baths 1.
  • This solution which is depleted of layer-forming components, is supplemented with aqueous solutions which make it possible to adjust the acid ratio and the concentrations of the components essential for the layer formation.
  • the desludged solution is mixed with aqueous solutions which adjust the acid ratio to a range from 7 to 15 and the concentrations of phosphoric acid to a range from 10 to 40 g.
  • the phosphoric acid in amounts of 300 to 700 g. l ⁇ 1, nitric acid in amounts of 30 to 300 g. l ⁇ 1, nickel (II) nitrate in amounts of 0 to 50 g. l ⁇ 1, Cu (OH) 2.
  • CuCO3 in amounts of 0 to 3 g.
  • the amount of zinc required for re-sharpening is therefore lower than for the solutions for re-sharpening phosphating solutions described in the prior art, because the process for desludging the phosphating baths according to the invention virtually eliminates the layer-forming component zinc is not withdrawn.
  • the desludged aqueous solution supplemented with the components required for the layer formation is fed back to the phosphating bath, while a partial volume of the same is again branched off and in a continuous process of the separate device having three open chambers is fed.
  • the device 1 shows a top view of the device according to the invention for carrying out the process for desludging phosphating baths.
  • the device 1 consists essentially of three chambers, of which the first chamber is referred to as the oxidation chamber 11, the second chamber as the sludge conditioning chamber 15 and the third chamber as the sedimentation chamber 19.
  • the volume of the three chambers mentioned is different. They have a volume ratio in the range from 1: 0.05: 10 to 1: 1: 1, preferably a volume ratio of 1: 0.5: 5, the volumes of the chambers being in the order of oxidation chamber 11 / sludge conditioning chamber 15 / sedimentation chamber 19 are mentioned.
  • the partial volume of the phosphating solution to be desludged branched off from the phosphating bath is supplied to the oxidation chamber 11 via the feed opening 12.
  • the fumigation takes place with a gas containing O2, which is supplied to the oxidation chamber 11 via the fumigation unit 13.
  • the gassing unit 13 is preferably a tubular device with a central flow and a porous surface. This is connected to a pressure pump which is able to supply the gassing unit 13 an O2-containing gas, air in preferred embodiments.
  • a sintered polypropylene hose is used with particular advantage as the gassing unit 13. Processes for sintering such propylene polymers and the resulting products are known from the prior art and do not require any further explanation here.
  • a hose called Accurel-Rohr® PP from Enka AG has proven itself as a sintered polypropylene material.
  • the sintered polypropylene tube of commercial provenance preferably has an average pore size in the range from 0.10 to 5.0 ⁇ m, with the pore size from 0.12 to 0.30 ⁇ m being particularly preferred.
  • this material is able to supply oxygen or an O2-containing gas in the form of tiny gas bubbles to the oxidation chamber.
  • such tiny gas pearls can cause rapid oxidation of the entire oxidizable iron (II) ions in the phosphating solution to form iron (III), which is subsequently used as iron (III) phosphate is precipitated.
  • a pressure-resistant apparatus is in no way necessary for this.
  • the pearls of oxygen or gas containing O2 rise at normal pressure in the oxidation chamber 11 of the open apparatus 1 or are dissolved in the aqueous phase until saturation at normal pressure and the operating temperature.
  • the operating temperature is usually in the range of 40 to 60 ° C.
  • the solution saturated with oxygen and containing iron phosphate is transferred via the Device 16 for forcibly guiding the flow direction is fed to the overflow between the oxidation chamber 11 and the sludge conditioning chamber 15 and is guided in this in the downward direction.
  • the devices 16 for forcibly guiding the flow direction are deflection baffles in the form of U-shaped profiles, which are attached at a certain distance from the bottom of the respective chambers and can therefore be flowed from below with the solution.
  • the inner sides of the U-shaped profiles of the devices 16 face the overflow 14, which makes it possible to supply the solution from the bottom to the top of the overflow 14 on the side of the oxidation chamber 11, while from the top to the side of the sludge conditioning chamber 15 is guided below and leaves the device 16 for positive guidance of the flow direction at the lower end and enters the sludge conditioning chamber 15.
  • the sludge conditioning chamber 15 is equipped with a device 17 for stirring the solution.
  • This device preferably consists of a controllable agitator, the number of revolutions to 100 to 300 U. min ⁇ 1 can be set.
  • the sludge-containing solution leaves the sludge conditioning chamber 15 through the overflow 18 located at its upper end. In doing so, due to the relatively small volume of the chamber 15, such sludge particles are also entrained comparatively large grains are agglomerated.
  • the solution is guided downward by the device 16 for the forced guidance of the flow direction, which is preferably also a deflection baffle in the form of a U-shaped profile, the inside of the profile facing the overflow 18.
  • This device 16 is also mounted at a certain distance from the bottom of the sedimentation chamber 19, so that the solution can enter the sedimentation chamber 19 at the lower end.
  • FIGS. 2 and 3 A comparable run of the solution up to this point also results from FIGS. 2 and 3, in which the same numbers were used for the same device parts as in FIG. 1.
  • the solution with the conditioned sludge particles enters the sedimentation chamber 19 at the lower end of the device 16 for the forced guidance of the flow direction, where - because of the larger chamber volume, but also because of different possibilities of the flow guidance -
  • the flow of the solution to the sludge conditioning chamber 15 slows down.
  • larger sludge particles can sink into the sludge teat 20 immediately after entering the sedimentation chamber and do not even rise to the separating surfaces 24 of the sedimentation chamber 19.
  • Slightly lighter sludge grains are led through the flow into the area between the separation surfaces 24 of the sedimentation chamber 19.
  • the walls of the mud teat 20 also have an inclination 32 to the bath surface or to an imaginary parallel to the bath surface 30 of ⁇ 35 °.
  • the more or less granular sludge particles sink successively by gravity in the sludge teat 20 down to the sludge outlet 23 and can be separated there separately.
  • the sludge drainage device 23 arranged at the lower end of the sludge teat 20 has its own pressure cleaning system, which makes it possible to remove incrustations or deposits of iron phosphate sludge that may have occurred in the area of the drain 23 under pressure.
  • water is supplied to the pressure cleaning system 23, which enables cleaning in a satisfactory manner.
  • a pressure cleaning system can, for. B. be a cleaning nozzle operated with water under increased pressure.
  • the aqueous bath medium freed from sludge particles runs over the serrated strip 21, which is shown in FIG. 4 in a greatly enlarged form, in particular through the V-shaped valleys 28 of the serrated strip 21, to the outlet opening 22, which also carries the phosphating solution freed from the sludge after re-sharpening feeds the components required for the phosphating back to the phosphating bath.
  • the device 1 according to the invention is manufactured from polypropylene.
  • the main advantage of using polypropylene is that the material is completely hydrophobic and does not allow polar solution components to settle on the surface of the device 1 and thus cause incrustations. This can be seen in contrast to conventional devices, in which it always had to be expected that solution components would undergo chemical reactions with the material of the device and thus irreversibly change or cause incrustations, which would lead to malfunctions in the operation of the device.
  • the polypropylene material of the device is completely smooth on the side that comes into contact with the solution constituents in order to also completely mechanically exclude the possibility of attack by the surface of the solvent constituents, in particular the granular iron (III) phosphate precipitates.
  • the device according to the invention alone, but also in connection with the method described above, has Compared to the prior art, there are a number of advantages in terms of process technology, some of which have already been explained in detail in the preceding description.
  • the iron (III) phosphate sludge does not arise in the bath, but is, surprisingly, exclusively in the oxidation chamber 11 and by the oxidation with oxygen-containing gases, in particular by air oxidation the sludge conditioning chamber 15 of the device according to the invention.
  • air oxidation is expressly described in the prior art as uneconomical and therefore practically impracticable, since it requires a pressure-resistant system suitable for working under excess pressure.
  • the method according to the invention was also used for Surprisingly, the skilled worker is also able to re-sharpen the solutions with corresponding aqueous solutions which enable the desired ratios or concentrations to be re-established in the bath. This ensures that the process parameters are fully consistent over the entire phosphating process, and there are always exactly defined phosphating layers that are identical in their layer composition.
  • the process according to the invention and the treatment in the device described in more detail above also ensure that the iron (III) phosphate sludge formed by the oxidation process with fine-bubbled, oxygen-containing gases is easily settled and does not, as usual, form voluminous flakes in the whole solution is distributed and possibly washed out.
  • the treatment with the fine-pearled, oxygen-containing gases produces granular, finely dispersed sludges, which are further improved in their sedimentation properties by the conditioning in the sludge conditioning chamber 15.
  • Another advantage is that in those cases in which the phosphated parts are subsequently subjected to a drawing or pressing process, the surfaces of the metallic bodies are treated with drawing soaps after the phosphating process, which essentially consist of alkali metal stearates.
  • the effect of these is influenced by the introduction of Ca2+ ions (by hard water) and by Fe ions (by iron in an increased concentration in the phosphating solutions), since insoluble calcium or iron stearates form.
  • Such metallic impurities from iron ions are then reduced If the iron concentration is removed by continuous precipitation of the iron formed in the form of iron (III) phosphate.
  • the drawing soaps applied after the phosphating can then take full effect.
  • the phosphating solution contained the components Zn2+, phosphate and nitrate in the following amounts: 21.1 g. l ⁇ 1 Zn2+; 20.6 g. l ⁇ 1 phosphate and 33.0 g. l ⁇ 1 nitrate.
  • the iron (II) content of the bath solution could be brought to 3.0 g by the continuous by-pass operation of the plant according to the invention, described in more detail above. l ⁇ 1 are kept constant.
  • the phosphating solution contained the components Zn2+, phosphate and nitrate, initially in the following amounts: 18.0 g. l ⁇ 1 Zn2+; 30.0 g. l ⁇ 1 phosphate and 22.0 g. l ⁇ 1 nitrate.
  • the concentration of the three components mentioned was maintained by supplementing with resharpening solutions which had the following composition: 192 g. l ⁇ 1 Zn2+; 600 g. l ⁇ 1 phosphate and 80 g. l ⁇ 1 nitrate.
  • iron (II) could be oxidized to iron (III) from the phosphating solutions carried in the by-pass through the apparatus according to the invention, precipitated as iron (III) phosphate and as such via the outlet 23 of the mud teat 20 (see Figures 1 to 3) can be removed.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Treating Waste Gases (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Saccharide Compounds (AREA)
EP88120522A 1987-12-16 1988-12-08 Procédé pour éliminer les boues des bains de phosphatation et appareil pour ce procédé Expired - Lifetime EP0320798B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88120522T ATE77663T1 (de) 1987-12-16 1988-12-08 Verfahren zur entschlammung von phosphatierungsbaedern und vorrichtung fuer dieses verfahren.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873742634 DE3742634A1 (de) 1987-12-16 1987-12-16 Verfahren zur entschlammung von phosphatierungsbaedern und vorrichtung fuer dieses verfahren
DE3742634 1987-12-16

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EP0320798A1 true EP0320798A1 (fr) 1989-06-21
EP0320798B1 EP0320798B1 (fr) 1992-06-24

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EP88120522A Expired - Lifetime EP0320798B1 (fr) 1987-12-16 1988-12-08 Procédé pour éliminer les boues des bains de phosphatation et appareil pour ce procédé

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Country Link
US (1) US4968360A (fr)
EP (1) EP0320798B1 (fr)
JP (1) JPH01198488A (fr)
AT (1) ATE77663T1 (fr)
AU (1) AU605658B2 (fr)
BR (1) BR8806633A (fr)
DE (2) DE3742634A1 (fr)
ES (1) ES2032938T3 (fr)
TR (1) TR23893A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6171409B1 (en) 1998-07-18 2001-01-09 Henkel Kommanditgesellschaft Auf Aktien Process for the chemical treatment of metal surfaces and installation suitable therefor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3913089A1 (de) * 1989-04-21 1990-10-25 Henkel Kgaa Chlorat- und nitritfreies verfahren zur herstellung von nickel- und manganhaltigen zinkphosphatschichten
US5273667A (en) * 1991-09-12 1993-12-28 Gill Colman A Recovery and utilization of phosphate sludge
DE4226080A1 (de) * 1992-08-06 1994-02-10 Henkel Kgaa Aufbereitung wäßriger Spüllösungen aus Zinkphosphatierungsprozessen
US5376342A (en) * 1993-04-09 1994-12-27 Waite; Michael D. Process for recovering zinc phosphating make-up feed from zinc phosphate sludge
DE10208400B4 (de) 2001-02-28 2018-03-29 Volkswagen Ag Verfahren zur Phosphatierung von metallischen Oberflächen und eine Verwendung des Verfahrens
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US3992300A (en) * 1972-09-27 1976-11-16 Trw Inc. Apparatus for controlling iron content of a zinc phosphating bath
GB2114161A (en) * 1982-01-20 1983-08-17 Nihon Parkerizing Phosphate immersion treatment of steel sheet structures

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ATE77663T1 (de) 1992-07-15
JPH01198488A (ja) 1989-08-10
BR8806633A (pt) 1989-08-29
TR23893A (tr) 1990-10-17
US4968360A (en) 1990-11-06
EP0320798B1 (fr) 1992-06-24
ES2032938T3 (es) 1993-03-01
DE3742634A1 (de) 1989-06-29
AU2689588A (en) 1989-06-22
AU605658B2 (en) 1991-01-17
DE3872363D1 (de) 1992-07-30

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