DE102018130593A1 - Surface treatment plant, preconditioning device and method for processing process medium and / or rinsing medium - Google Patents

Abstract

A surface treatment system (10) for treating objects (14), in particular vehicle bodies, has a thin film conversion process (20) in which a ceramic thin film is applied to the objects (14) using a process medium, a subsequent rinsing step (22, 24), in which the objects (14) are rinsed with rinsing medium (33) after the thin-film conversion process (20), and a deionization system (28) which has a cation exchanger (52) and a downstream anion exchanger (54) and is set up to process the process medium and / or to deionize the rinsing medium (33). For economical operation, the deionization system (28) is preceded by a preconditioning device (30) which is set up to remove complex anions, which are formed and / or are present in the thin-film conversion process (20), from the process medium and / or the rinsing medium (33 ) to remove. A corresponding preconditioning device and a method for processing are also described.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

1. a) einem Dünnschichtkonversionsprozess, in welchem unter Verwendung eines Prozessmediums eine keramische Dünnschicht auf den Gegenständen aufgebracht wird,
2. b) einem anschließenden Spülschritt, in welchem die Gegenstände nach dem Dünnschichtkonversionsprozess mit Spülmedium gespült werden, und
3. c) einer Entionisierungsanlage, die
   • - einen Kationenaustauscher und einen nachgeschalteten Anionenaustauscher aufweist und
   • - dazu eingerichtet ist, das Prozessmedium und/oder das Spülmedium zu entionisieren.

The invention relates to a surface treatment installation for treating objects, in particular vehicle bodies

1. a) a thin film conversion process in which a ceramic thin film is applied to the objects using a process medium,
2. b) a subsequent rinsing step in which the objects are rinsed with rinsing medium after the thin-film conversion process, and
3. c) a deionization plant, the
   • - Has a cation exchanger and a downstream anion exchanger and
   • - is set up to deionize the process medium and / or the rinsing medium.

The invention further relates to a preconditioning device and a method for the preparation of process medium and / or rinsing medium in the surface treatment of objects.

Description of the prior art

Metallic materials must be protected against damaging corrosion. Therefore, the metal surface of objects in surface treatment plants is usually covered with protective coatings. Varnishes that form a closed film made of organic polymers have proven successful for this.

Good adhesion to the material is important so that the paint can perform its protective function. In order to ensure reliable paint adhesion, the metallic materials must be pretreated before painting.

The pretreatment before painting usually includes cleaning processes for removing contaminants and / or pickling processes for removing rust, for example, or scale layers, and in particular a conversion process for applying a primer to the workpiece surface.

For a summary of the processes used in the pretreatment, reference is made to the as yet unpublished DE 10 2018 115 289 referred to the applicant.

So-called phosphating has been used as the preferred conversion process for decades. A conversion layer of metal phosphates is formed on the workpiece surface by applying appropriate chemicals. Due to its structured surface, this phosphate layer offers good adhesion for the subsequent lacquer layers. The corrosion protection properties of a workpiece with a phosphate layer and subsequent lacquer layers are many times better than without a corresponding phosphate layer.

Wet chemical pretreatment has proven itself in industrial surface treatment plants. There, the cleaning process, the pickling process and / or the conversion process are carried out in several treatment zones connected in series. The objects to be treated are transported through the zones via a conveyor system and are brought into contact with the respective aqueous process media there.

The contacting is usually carried out by spraying or flooding the process medium or by immersing the object in a process bath or combinations thereof. Regardless of the selected process control, which is specifically designed for each application, after the object has come into contact with the process medium, residues of the process medium remain on the surface of the object. These residues are carried off into the subsequent treatment zone or even into several subsequent treatment zones, as a result of which they are increasingly contaminated. The contaminants can have an adverse effect on the treatment process in this subsequent treatment zone.

In order to minimize the harmful effects of this carry-over on subsequent treatment zones, additional rinsing zones are installed downstream of the cleaning zones, the pickling zones and the conversion zones. In the rinsing zones, the objects are rinsed with raw water and / or fully deionized water (deionized water), whereby the remnants of the process medium are absorbed in the rinsing water. The impurities accumulating in the rinsing water can be discharged as waste water by continuous or intermittent discharge and diluted by supplying fresh water.

Another possibility to remove disturbing impurities from rinse water but also from other process liquids of the pretreatment is the use of so-called bath maintenance measures. Contamination is separated by technical separation processes, which means that prolonged use of the process medium and / or the flushing medium is possible. As a result, the consumption of process medium, the fresh water consumption and / or the amount of waste water can be reduced.

A frequently used bath care measure is the use of ion exchangers (IAT). With this technology, ions that are dissolved in water can be removed. In the case of pretreatment, it is state of the art to clean the last rinsing zones, that is to say the rinsing water, after using phosphating as a conversion process via ion exchangers. The rinse water to be cleaned is first conveyed through a filter, usually a gravel filter, to remove coarser particles, such as iron hydroxide sludge. The rinsing water then flows through a cation exchanger (CAT) in which there is a solid bed of special particles that are able to exchange positively charged ions in the process water for hydrogen ions (H ⁺ ions).

The rinsing water then flows through an anion exchanger (ANT), in which negatively charged ions are exchanged in a similar manner for hydroxide ions (OH ^- ions).

The hydrogen ions and the hydroxide ions neutralize each other to normal water (H ₂ O), so that almost ion-free water leaves the entire ion exchanger.

The cleaned rinsing water can then be returned to the rinsing zones and used again. If an ion exchanger is exhausted because it has reached its dirt ion absorption capacity, it must be regenerated. For this purpose, the cation exchanger is usually regenerated with an acidic hydrochloric acid solution (HCl) and the anion exchanger with an alkaline sodium hydroxide solution (NaOH).

In recent years, however, phosphating as an established conversion process in pretreatment has been replaced by alternative processes based on zirconium, titanium and / or silicon compounds. In this so-called thin-film conversion, a nanoscale ceramic conversion layer is produced on the surface of the object under the influence of chemicals. One therefore speaks of a nanoceramic. The conversion layer formed then consists essentially of oxidic compounds (e.g. ZrO ₂ , TiO ₂ , SiO ₂ ).

The thin film conversion process based on zirconium, titanium and / or silicon compounds is not only used to completely replace the phosphating but can also be used as a supplement to the classic phosphating. In this case, the thin film conversion process is often referred to as a rinse solution or passivation. Especially in the surface treatment of vehicle bodies, where higher quality standards apply, rinsing often follows after phosphating, then a thin-film conversion called passivation and then rinsing again. It is assumed that through the passivation, free metal surfaces that have not been adequately phosphated are passivated through the thin-film conversion, thereby increasing the corrosion protection. The chemical compositions of the thin film conversion process replacing the phosphating and of the thin film conversion process supplementing the phosphating are largely similar.

SUMMARY OF THE INVENTION

The object of the invention is now to provide a surface treatment plant for thin-film conversion treatment, which further allows the processing of process medium and / or rinsing medium.

• d) der Entionisierungsanlage eine Präkonditionierungseinrichtung vorgeschaltet ist, die dazu eingerichtet ist, Komplex-Anionen, welche bei dem Dünnschichtkonversionsprozess entstehen und/oder vorhanden sind, aus dem Prozessmedium und/oder dem Spülmedium zu entfernen.

According to the invention, this is solved by a surface treatment installation of the type mentioned at the beginning, in which

• d) the deionization system is preceded by a preconditioning device, which is set up to remove complex anions which arise and / or are present in the thin-film conversion process from the process medium and / or the rinsing medium.

The inventors have recognized that the previous series connection of gravel filter, cation exchanger and anion exchanger in a deionization system for the preparation of process medium and / or rinsing medium is no longer possible without problems. When using the known techniques, solid precipitates occur in the deionization plant, which causes the ion exchangers to block after only a few operating cycles. This is associated with an increase in the flow pressure loss and a decrease in the ion exchange capacity.

The inventors have further recognized that the undesired solid precipitation in the deionization system occurs in particular in the preparation of rinsing medium if zirconium, titanium and / or silicon compounds are present in the rinsing medium which are due to the thin-film conversion process.

In addition, the inventors recognized that the regular regeneration of the anion exchanger in the deionization plant with a sodium hydroxide solution was the trigger for the solid precipitation. Analyzes then showed that the precipitated solids in water and / or in acid comprised sparingly soluble (hydr) oxidic compounds of zirconium, titanium and / or silicon.

It was recognized that the compounds of zirconium (Zr), titanium (Ti) and silicon (Si) used in the thin-layer conversion process, such as, for example, hexafluorozirconic acid (H ₂ ZrF ₆ ), hexafluorotitanic acid (H ₂ TiF ₆ ), hexafluorosilicic acid (H ₂ SiF ₆ ) and / or their readily soluble alkali metal salts, ammonium salts and / or also thin film conversion solutions in the form of (organo -) silanes in the process medium and / or rinsing medium as water-soluble complex ions. For example, these are [ZrF ₆ ] ^2- ions, [TiF ₆ ] ^2- ions and / or [SiF ₆ ] ^2- ions. However, the stability of the complex ions depends on the pH of the solution, which means that when the anion exchanger is regenerated in the deionization system with sodium hydroxide solution, the poorly soluble hydroxides, oxides and / or oxy hydroxides precipitate out as a solid.

According to the invention, the inventors therefore propose to provide a preconditioning device which removes the complex anions from the process medium and / or the rinsing medium before they enter the deionization system. As a result, a conventional demineralized water system according to the prior art can continue to serve as a deionization system. Their main purpose can be to produce demineralized water from raw water or fresh water. By means of the preconditioning device, process medium and / or rinsing medium can also be used as it were.

For the purposes of the invention, removing the complex anions comprises removing the complex anions at least to the extent that the deionization system can be operated economically.

It is preferably provided that the preconditioning device has an anion exchanger which is set up to exchange the complex anions for other anions.

As will become clearer below, an anion exchanger as a preconditioning device represents an economically sensible way to remove the interfering complex anions in front of the deionization plant. These other anions, the so-called exchange ions, should in particular be those which are problematic for the subsequent deionization plant neither in the deionization operation nor during the regeneration, for example leading to blocking of the exchange material. In the preconditioning device, the process medium and / or rinsing medium flowing through is thus salted over. During the salting process, the disruptive complex anions are replaced by other salt anions (ie in particular not by OH ^- ions) which do not cause any disturbances in the subsequent demineralized water system.

Acidic residual anions such as, for example, phosphate (PO ₄ ^3- ) and / or hydrogen phosphates (HPO ₄ ^2- and H ₂ PO ₄ ^- ) are generally suitable as exchange anions. However, preferably acid residue anions of strong to medium strength acids, such as the acid residues of hydrochloric acid, nitric acid or sulfuric acid. For example, these can also be the residual acid anions iodide (I ^- ), bromide (Br ^- ), fluoride (F ^- ) and / or hydrogen sulfate (HSO ₄ ^- ). Replacement with chloride (Cl ^- ), nitrate (NO ₃ ^- ) or sulfate (SO ₄ ^2- ) is therefore particularly favorable.

The residual acid anions leave the preconditioning device together with the process medium and / or the rinsing medium.

The complex anions remain in the anion exchanger so that it has to be regenerated from time to time. This is done by a regenerating agent, which contains the acid residue in concentrated form. The regenerate, which contains the regenerant and the complex anions, is derived and / or collected. In the best case, the complex anions can be separated off, for example, by a regeneration device and returned to the thin-film conversion process.

It is preferably provided that the anion exchanger of the preconditioning device comprises a selective exchanger material.

As a result, the preconditioning device can only be designed to exchange the complex anions. Other anions that are not problematic for the subsequent deionization plant can remain in the process medium and / or in the rinsing medium. This leads to a lower load on the anion exchanger in the preconditioning device.

It is preferably provided that the anion exchanger of the preconditioning device is regenerated with a regenerating agent that has a pH value of less than approximately 6.

As a result of the fact that the anion exchanger of the preconditioning device is regenerated in acid, the complex anions do not precipitate out but are present in dissolved form in the regenerate. To do this, the regenerant preferably have acidic resections of strong acids. Acid resections of strong acids (such as hydrochloric acid HCl; nitric acid HNO ₃ or sulfuric acid H ₂ SO ₄ ) do not shift the pH value, whereas acid resections of medium strong or weak acids can increase the pH value. Regenerating agents are considered suitable which contain the acid residue together with its corresponding acid. Aqueous solutions of nitrate salt (e.g. sodium nitrate) with nitric acid or of sulfate salt (e.g. sodium sulfate) with sulfuric acid are suitable. An aqueous solution of a sodium chloride solution (NaCl) with hydrochloric acid (HCl) has proven particularly suitable. Alternatively, of course, only HCl or only NaCl can be used, i.e. only the acid or only the salt.

It is important that the regeneration does not increase the pH of the anion exchanger in the preconditioning device, as otherwise solids would precipitate.

After the regeneration, it is preferably rinsed with water and the anion exchanger is again available for cleaning the process medium and / or rinsing medium.

It is preferably provided that the preconditioning device has a further anion exchanger in addition to the anion exchanger so that the two anion exchangers can be operated and regenerated alternately.

This leads to a continuous delivery of process medium and / or rinsing medium, whereby the deionization system can be continuously fed and operated.

It is preferably provided that the preconditioning device has a device for precipitating the complex anions from the process medium or the rinsing medium and a subsequent separation device.

Compared to the anion exchanger, this represents another possibility of protecting the deionization plant from the complex anions, which are problematic and harmful for the operation or regeneration of the exchangers contained therein. For this purpose, a precipitant (possibly also a flocculant and / or flocculant) is added to the process medium and / or the rinsing medium in the preconditioning device in order to precipitate the interfering complex anions. In the simplest case, this is a means of shifting the pH value into the alkaline range. This can be, for example, sodium hydroxide solution or lime milk.

A wide variety of methods can be used as separation devices in order to separate the solids from the solution. These are, for example, filtration, sedimentation, centrifuges, cyclones or the like.

The device for precipitation and the separation device can also be combined in a common unit.

Finally, the anion exchanger and the device for precipitation and the separation device can also be provided in addition.

It is preferably provided that the rinsing medium of several sinks is fed to the preconditioning device.

This allows the fresh water requirement to be reduced further and / or the installation effort to be reduced.

It is preferably provided that the surface treatment system has a controller which is set up to operate and regenerate the preconditioning device in such a way that the complex anions reach the deionization system in a harmless concentration at most.

The controller can use various pumps, valves and / or ESMR measuring points.

According to another aspect of the invention, a preconditioning device is provided which is intended to be connected upstream of a deionization plant of a surface treatment plant and which is set up to process complex anions which arise and / or are present in a thin film conversion process of the surface treatment plant from a process medium and / or to remove a flushing medium.

Such a preconditioning device can be inserted into existing surface treatment plants if these are to be converted from a known phosphating process to a thin-film conversion process. In this way, the previously used deionization plant can continue to be used.

1. a) Bereitstellen einer Entionisierungsanlage, die
   • - einen Kationenaustauscher und einen nachgeschalteten Anionenaustauscher aufweist und
   • - dazu eingerichtet ist, das Prozessmedium und/oder das Spülmedium zu entionisieren;
2. b) Bereitstellen einer Präkonditionierungseinrichtung, die der Entionisierungsanlage eine Präkonditionierungseinrichtung vorgeschaltet ist und die dazu eingerichtet ist, Komplex-Anionen, welche bei dem Dünnschichtkonversionsprozess entstehen und/oder vorhanden sind, aus dem Prozessmedium und/oder dem Spülmedium zu entfernen;
3. c) Entfernen der Komplex-Anionen aus dem Prozessmedium und/oder dem Spülmedium.

According to another aspect of the invention, a method for preparing process medium from a thin-film conversion coating process in a surface treatment system and / or of rinsing medium from subsequent rinsing steps is specified with the following steps:

1. a) Providing a deionization plant, the
   • - Has a cation exchanger and a downstream anion exchanger and
   • - is set up to deionize the process medium and / or the rinsing medium;
2. b) provision of a preconditioning device which is connected upstream of the deionization system and which is set up to remove complex anions which arise and / or are present in the thin-film conversion process from the process medium and / or the rinsing medium;
3. c) removing the complex anions from the process medium and / or the rinsing medium.

With such a method, the process medium and / or the rinsing medium can also be prepared in a thin-film conversion process.

Figure list

• 1 eine Oberflächenbehandlungsanlage mit einer Entionisierungsanlage und einer erfindungsgemäßen Präkonditionierungseinrichtung;
• 2 eine Oberflächenbehandlungsanlage mit einer Entionisierungsanlage und einer erfindungsgemäßen Präkonditionierungseinrichtung nach einem anderen Ausführungsbeispiel;
• 3 eine Oberflächenbehandlungsanlage mit einer Entionisierungsanlage und einer erfindungsgemäßen Präkonditionierungseinrichtung nach einem weiteren Ausführungsbeispiel.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. In these show:

• 1 a surface treatment plant with a deionization plant and a preconditioning device according to the invention;
• 2nd a surface treatment plant with a deionization plant and a preconditioning device according to the invention according to another embodiment;
• 3rd a surface treatment plant with a deionization plant and a preconditioning device according to the invention according to a further embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

1 shows a total of 10 surface treatment system with a conveyor system 12 what items 14 , here in the form of vehicle bodies, through the individual treatment steps of the surface treatment system.

The in 1 shown section from the surface treatment plant 10th initially includes two sinks 16 and 18th that follow a previous treatment step, for example cleaning.

Furthermore, the surface treatment plant 10th to carry out a thin film conversion process a thin film conversion basin 20th which is designed here as a plunge pool.

The thin film conversion process is followed by two rinsing steps in the form of a rinsing cascade. To do this, here is the thin-film conversion basin 20th a spray sink 22 arranged, which with overflow water from the subsequent sink 24th is operated, which is designed as a plunge pool. The overflow water can from the sink 24th to the spray sink 22 overflowed or actively pumped.

The sink 24th is, however, with fully demineralized water (DI water) from a pipe 26 fed.

The administration 26 is in turn from a deionization plant 28 fed, which generates the demineralized water and is therefore often referred to as demineralized water system.

The surface treatment plant 10th also has a preconditioning device 30th on.

The preconditioning facility 30th is via a drain line 32 from the sink 24th with contaminated rinse water 33 fed. An exit 34 the preconditioning device 30th is with a raw water tank 36 connected, from which in turn via a line 38 the deionization plant 28 is fed.

The raw water tank 36 also has a raw water feed line 40 on which raw water or well water can be fed into the system from the municipal water supply.

Finally leads from the spray sink 22 another sewage pipe 42 into a sewage system, not shown, or a chemical-physical wastewater treatment plant of the company.

The surface treatment plant 10th further points, as in 1 hinted at a controller 44 on, which is set up across different measuring points 46 , Pump 48 and valves 50 monitor and control the processes of the plant.

The deionization plant 28 has a cation exchange column inside 52 and an anion exchange column 54 on. With the help of the cation exchange column 52 positively charged ions are exchanged for hydrogen ions (H ⁺ ions). In the following anion exchange column 54 however, negatively charged ions are exchanged for hydroxide ions (OH ^- ions). As the corresponding ion exchange materials become exhausted over time, they have to be used from time to time be regenerated. For this purpose, the deionization system has a regenerant inlet for each column 56 and 58 as well as corresponding regenerate outputs 60 and 62 on.

The preconditioning facility 30th demonstrates in the exemplary embodiment 1 an anion exchange column 64 with a selective exchange material. Here too there is an inlet for the regenerant 66 as well as a regenerate outlet 68 intended.

• Im Dünnschichtkonversionsbecken 20 werden die Gegenstände mit einer nanoskaligen Keramikschicht überzogen. Die dabei verwendeten Chemikalien beinhalten Verbindungen von Zirkonium (Zr), Titan (Ti) und Silizium (Si) als Fluoridkomplexe. Dies sind beispielsweise Hexafluorzirkonsäure (H₂ZrF₆), Hexafluortitansäure (H₂TiF₆) und Hexafluorkieselsäure (H₂SiF₆) oder deren leicht lösliche Alkalisalze und/oder Ammoniumsalze. Auch können Dünnschichtkonversionslösungen in Form von (Organo-)Silanen eingesetzt werden.

The surface treatment plant 10th works as follows:

• In the thin-film conversion basin 20th the objects are covered with a nanoscale ceramic layer. The chemicals used include compounds of zirconium (Zr), titanium (Ti) and silicon (Si) as fluoride complexes. These are, for example, hexafluorocirconic acid (H ₂ ZrF ₆ ), hexafluorotitanic acid (H ₂ TiF ₆ ) and hexafluorosilicic acid (H ₂ SiF ₆ ) or their readily soluble alkali metal salts and / or ammonium salts. Thin-film conversion solutions in the form of (organo) silanes can also be used.

These compounds get into the two subsequent sinks by dragging on the objects from the thin-film conversion process 22 and 24th .

In the preconditioning facility 30th are in the running rinse water 33 contained complex anions from the thin-film conversion process, which contain zirconium, titanium or silicon, exchanged for other anions, acid residues generally being considered here. In the anion exchange column 64 the preconditioning device 30th thus finds a salting over the selective exchange material for the deionization plant 28 problematic complex anions instead.

The residual acid anions then leave the preconditioning device 30th together with the rest of the rinse water 33 over the line 34 and are in the raw water tank 36 brought in. From there, they are fed with fresh water, if necessary, to maintain the total amount of liquid in the system of the surface treatment system 10th into the deionization plant 28 .

In the deionization plant 28 in a manner known per se, the cations are first exchanged for hydrogen cations and then the anions for the hydroxide anions, with the salting in the preconditioning device 30th into the exchange material of the deionization plant 28 unproblematic anions are stored for later regeneration.

The deionization plant 28 can thus be regenerated in a known manner, specifically by using the cation exchange column 52 acid is regenerated and the anion exchange column 54 is regenerated alkaline. It therefore comes in the deionization plant 28 not blocking the ion exchange material due to precipitation of the complex anions in the alkaline regeneration.

For regeneration of the anion exchange column 66 the preconditioning device 30th instead of an alkaline regeneration, regeneration is carried out in the acidic or neutral range. For this purpose, at the regenerant inlet 66 the anion exchange column 64 Regenerating agents are used that have a pH value less than 6. This can be achieved by acid residue ions of strong acids, since these do not shift the pH value, whereas acid residue ions of medium or weak acids would increase the pH value, causing the complex anions in the anion exchange column 64 in the preconditioning facility 30th would fail.

Since in the embodiment 1 at the preconditioning facility 30th shows additional regrind compared to the prior art, shows 2nd an embodiment improved in this regard, wherein components of similar or identical function are designated by the same reference numerals.

How to 2nd can be seen here at the deionization plant 28 resulting regenerate at least in parts of the preconditioning device 30th supplied as a regenerant.

For this purpose, the two or just one of the two regenerate outputs 60 , 62 the deionization plant 28 with a regrind tank 70 connected. A branch option is not shown in order to discard regenerate instead of this to the regenerate tank 70 respectively. The regenerate tank 70 is also connected to the regenerant inlet 66 the preconditioning device 30th connected. This makes it possible to use regenerating agents several times and / or to reduce the installation effort.

For example, the cation exchange column 52 with hydrochloric acid (HCl) in excess as a regenerant. The foreign ions from the cation exchange column are then in the so-called flow of the regenerate, ie at the beginning of the regeneration 52 initially contained in high concentration. This advance of the regrind can be discarded via the branch option. Then the concentration of foreign ions in the regenerate drops and it is then in the regenerate tank 70 collected. That in the regenerate tank 70 Regenerate contained, however, has a slightly lower acidity than the regenerant at the inlet, ie a slightly higher pH value.

With this less concentrated hydrochloric acid as regeneration agent, the anion exchange column becomes 64 the preconditioning device 30th fed.

Another option is to use the ions in the anion exchange column 64 exchanged for the complex anions (for example Cl ^- ions) and via the raw water into the deionization plant 28 get to reuse. Because these ions accumulate during normal operation of the deionization system 28 initially in the anion exchange column 54 and are exchanged for OH ^- ions. During regeneration, these Cl ^- ions can be stored in the regenerate tank 70 are collected from where you as regeneration agent back into the anion exchange column 64 the preconditioning device 30th reach. This creates a cycle, which reduces the need for regenerants and further reduces raw water consumption.

However, additional measuring technology for monitoring the regenerate and further metering options are necessary.

Finally shows 3rd another embodiment in which the preconditioning device 30th An institution 72 for the precipitation of the complex anions and a subsequent separation device 74 , such as sedimentation and / or filtration, for separating the precipitated solids from the aqueous rinse water 33 includes.

In this embodiment, the deionization system 28 problematic complex anions from the thin film conversion process by adding appropriate precipitation chemicals to a precipitant inlet 76 precipitated out of the rinse water. For example, the pH can be shifted to alkaline. Flocculants can also be used which support flocculation of the solids.

The separation device 74 is with the raw water tank 36 connected, in which the raw water as in the previous embodiments for further treatment in the deionization plant 28 is collected.

How out 3rd can also be seen, the rinse water 33 also the spray sink 22 be removed. This applies to all exemplary embodiments.

Depending on the design of the system, the person skilled in the art is free to also carry out combinations of the above-mentioned exemplary embodiments.

It is conceivable, for example, in the embodiment according to 3rd after the separation device 74 another anion exchange column 64 according to the 1 and 2nd in the preconditioning facility 30th to provide.

The rinse water can also be from several sinks 22 and 24th be summarized.

It is also fundamentally conceivable to prepare the process medium of the thin-film conversion process in a similar way. Because also for the thin-film conversion coating basin 20th it may already be sensible to run off the process medium using a combination of preconditioning device 30th and a deionization plant 28 prepare and / or dispose of.

In a modification of the above exemplary embodiments, an activated carbon filter can be used as a prefilter in front of the preconditioning device in addition or as an alternative to a gravel filter. This can be used as an adsorptive filter e.g. Remove disruptive surfactants, biocides and / or disinfectants. In particular, if the demineralized water generated is not only to be returned to the rinsing process, but is also to be used in other process sections, an activated carbon filter can be provided depending on the specific application. An activated carbon filter following the preconditioning device and / or the deionization system can also be advantageous.

Regardless of the current subject matter of the invention, it was recognized that a preconditioning device according to the invention advantageously also in front of a membrane filtration system, e.g. a reverse osmosis system, for removing complex anions. This is because the complex anions described can also cause disturbances due to membrane blocking (also called fouling or scaling). For this reason, water that contains the ingredients of thin-film conversion has not previously been passed through membrane filtration systems. An upstream preconditioning device according to the invention could also remove the interfering complex anions here, as a result of which further deionization via the membrane filtration system would be possible.

The applicant reserves the right to pursue this idea further, for example in the context of divisional applications.

In particular, an inventive idea can generally be seen in the removal of complex anions from any water of surface treatment plants in the course of preconditioning with the aid of an anion exchanger, the pH of which is carried out as described.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102018115289 [0006]

Claims (10)

Surface treatment system (10) for treating objects (14), in particular vehicle bodies, with a) a thin-film conversion process (20), in which a ceramic thin film is applied to the objects (14) using a process medium, b) a subsequent rinsing step (22, 24), in which the objects (14) are rinsed with rinsing medium (33) after the thin-film conversion process (20), and c) a deionization system (28) which has - a cation exchanger (52) and a downstream anion exchanger (54) and - is set up to deionize the process medium and / or the rinsing medium (33), characterized in that d) the deionization system (28) is preceded by a preconditioning device (30) which is set up to remove complex anions which are used in the thin film conversion process ( 20) arise and / or are present to be removed from the process medium and / or the rinsing medium (33). Surface treatment plant after Claim 1 , characterized in that the preconditioning device (30) has an anion ion exchanger (64) which is set up to exchange the complex anions for other anions. Surface treatment plant after Claim 2 , characterized in that the anion exchanger (64) of the preconditioning device (30) comprises a selective exchange material. Surface treatment plant according to one of the Claims 2 to 3rd , characterized in that the anion exchanger (64) of the preconditioning device (30) is regenerated with a regenerating agent that has a pH of less than approximately 6. Surface treatment plant according to one of the Claims 2 to 4th , characterized in that the preconditioning device (30) in addition to the anion exchanger (64) has a further anion exchanger, so that the two anion exchangers are operated and regenerated alternately. Surface treatment plant according to one of the preceding claims, characterized in that the preconditioning device (30) has a device (72) for precipitating the complex anions from the process medium or the rinsing medium (33) and a subsequent separation device (74). Surface treatment system according to one of the preceding claims, characterized in that the rinsing medium (33) of a plurality of sinks (22, 24) is fed to the preconditioning device (30). Surface treatment system according to one of the preceding claims, characterized in that the surface treatment system has a controller (44) which is set up to operate and regenerate the preconditioning device (30) in such a way that the complex anions are at most in a harmless concentration in the deionization system (28). Preconditioning device which is provided to be connected upstream of a deionization plant (28) of a surface treatment plant (10) and which is set up to complex anions which arise and / or are present in a thin film conversion process (20) of the surface treatment plant (10), to be removed from a process medium and / or a rinsing medium (33). Method for processing process medium from a thin-film conversion coating process (20) in a surface treatment system (10) and / or rinsing medium (33) from subsequent rinsing steps (22, 24) with the following steps: a) providing a deionization system (28), the - A cation exchanger (52) and a downstream anion exchanger (54) and - is set up to deionize the process medium and / or the rinsing medium (33); b) provision of a preconditioning device (30) which is connected upstream of the deionization plant (28) and which is set up to remove complex anions which are formed and / or are present in the thin-film conversion process (20) from the process medium and / or the rinsing medium ( 33) remove; c) removing the complex anions from the process medium and / or the rinsing medium (33).

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