EP3483304B1 - Method and device for surface treatment - Google Patents

Description

The present invention relates to a method and a device for surface treatment, in particular the cleaning of metallic surfaces with the aid of adjustable flows.

Objects or bodies made of metal are cleaned before possible surface treatments, for example electroplating, galvanizing or similar surface treatments, in order to remove particles and residues or impurities on the surface and to obtain surfaces free of contaminants for subsequent treatment of the metallic object.

In the prior art, bodies are cleaned in appropriate baths, such as degreasing baths, and / or treated in pickling baths during cleaning. In both cleaning processes, the surface of the body is cleaned, for example by removing the adhering fat and / or oil in the degreasing process and other deposits such as rust and / or scale in the stain. The baths are made up of basins into which the body to be treated is introduced and remains for a certain time until a corresponding cleaning or pickling result is achieved. With this so-called static cleaning or static pickling, the material surface is treated with no or only minimal movement of the cleaning and / or pickling liquid. The static baths for cleaning and / or pickling normally include one or two positions for trusses with material. The speed of cleaning is determined by the chemical composition, the substance concentration (s) of the cleaning solution and / or pickling solution and the temperature. The disadvantage of the static systems is that the speed of cleaning and the pickling process is very slow and there is no exchange of substances in the boundary layer areas to be treated between the body (component) and the process fluid. In the prior art, the speed of the pickling is increased with the help of turbines, in that they put the pickling liquid in a turbulent state. The main disadvantage of the method shown is that the turbines used not only have considerable dimensions, which affects the possible pickling positions in the The bath is reduced, the basin is also divided in order to use the effects of the turbine, which in turn leads to a reduction in the size of the basin and the pickling positions.

Basins with circulation pumps that generate a current are for example the Korean application KR 2006 0112942 A refer to.

The Chinese filing CN 203 999 830 U also describes, for example, a method and an associated device for pickling stainless steel in a basin, in which acidic liquid is passed into the basin through a distribution pipe with a circulating pump.

In the German registration DE 28 03 072 A1 describes a device for the reproducible determination of the removability of substances applied to a support body by a solvent, in which a circulating flow is generated within a basin in which the support body is arranged.

The object of the present invention is therefore to provide a method and a device which provides an optimal surface treatment, in particular the cleaning of metal surfaces, without the disadvantages mentioned in the prior art, the reduced cleaning and / or pickling speed and the Loss of area within the process bath.

The present invention therefore relates to a method for chemical surface treatment of bodies according to claim 1, wherein a laminar flow is generated within the liquid of at least one process basin for degreasing and / or for pickling. In one embodiment, the stain is an iron and / or zinc stain. In one embodiment of the method according to the invention, the flow according to the invention swims around the body located in the at least one process basin. In one embodiment, the flooding of the body and the resulting movement at the boundary layer lead to the formation of a protective layer, a shift in the resting potential and / or a homogeneous cleaning surface.

In one embodiment, the laminar flow within the liquid is generated in at least one process basin for degreasing and / or for pickling by at least one flow pump arranged for each flow direction in the side area of the process basin. In this case, only the at least one pump is active for one flow direction, the at least one pump being inactive for the other flow direction. In a preferred embodiment, two or more pumps that interact with one another are provided for generating a flow direction in the process basin. In a particularly preferred embodiment, the pumps that interact with one another are each arranged diagonally on the opposite end faces of the process basin.

In the method according to the invention, the at least one flow pump, which generates a laminar flow, and the at least one Process basin located body washes around, a rectifier on.

In a further embodiment, in iron pickling, the iron (II) ion content can be reduced and the iron (III) ion content increased by means of a controllable regulation. In a preferred embodiment, the iron content in the process bath is regulated via a controllable supply of air and / or oxygen. In one embodiment, the iron content and / or the redox potential is monitored. Furthermore, in one embodiment, monitoring and regulation for suspended matter and temperature can be included. This monitoring and the regulation can also contribute to a further optimization of the degreasing process and / or pickling process.

In one embodiment of the present invention, a device for removing fats, oils and / or contaminants is provided. This can comprise at least one overflow, a fat / oil separation unit and / or a filtration unit.

The present invention also relates to an associated device for chemical surface treatment of bodies according to claim 6 according to the method presented above, wherein at least one process basin with process liquid and at least one pump per direction of flow for producing a laminar flow are included.

In one embodiment, the device has at least one degreasing bath and at least one bath for pickling.

In one embodiment, at least one rinsing bath can also be provided. The rinsing bath reduces the entry of contaminants into the subsequent processes, which means that this can be interposed between each step, i.e. each process bath.

In a further embodiment, the device has a monitoring and regulating mechanism that is used for determining, monitoring and / or regulating the temperature and / or concentrations of the substances contained in the process bath liquid are used.

In a further embodiment, the device comprises elements for removing fats, oils and / or contaminants. These elements can comprise at least one overflow, a fat / oil separation unit and / or a filtration unit.

The present invention is characterized by the embodiments in the claims and described in more detail by the embodiments in the following description and the drawings.

Description of the drawings

Fig. 1

Schematic representation of the degreasing process comprising a process bath (1) with laminar flow with an overflow (2) and separate containers (5, 6) for regeneration and disposal.

Fig. 2

Schematic representation of the iron pickling process comprising a process bath (1) with laminar flow with an overflow (2) and separate containers (5, 11) for regeneration as well as disposal and addition of fresh acid.

Fig. 3

Investigation of the weather resistance of bodies after pretreatment.

Fig. 4

Schematic representation of the flow course with two interacting pumps in the basin. a) Representation of a direction of flow clockwise (to the right) or b) counterclockwise (to the left).

List of reference symbols

1

Process bath or process basin

2

Overflow

3

Surface skimmer

4th

Oil / fat concentrate

5

Collection container

6th

Calming tank

7th

Fresh / rinse water / chemical supply

8th

pump

9

Air supply

10

HCl feed

11

Fresh acid container

12th

Removal of stain

13th

Oil separation

14th

Filter including pump

15th

Temperature control, concentration measurement unit; Heat exchanger

Detailed description of the invention

The present invention relates to a method and a device for the surface treatment of material surfaces of bodies, wherein a laminar flow profile is generated.

The term "approximately laminar" denotes a flow profile that runs laminar, but cannot run laminar in all areas due to the limited space in which the flow is generated. Areas in which the currents show changes in the course are, for example, edges, corners and shadow areas that are caused by bodies within a basin. In limited rooms or shadow areas in which the flow can be disturbed, turbulence can develop that does not allow a complete laminar flow. For this reason, the term "approximately laminar" flow describes that a pump produces a laminar flow, but due to the limited space, for example within a process basin, this generated laminar flow can only be approximately laminar because it is turbulent in some areas or may have flow shadows.

First of all, bodies can be all objects and items that can be surface treated. Bodies of the present invention are in particular parts and constructions, such as stair constructions, building constructions, steel girders, gratings, crash barriers (guardrails), which are mostly treated piece by piece.

The surface treatment includes the preparation and / or cleaning of the surface of the body for the following treatment, such as a wet / Powder coating, application of metallic (protective) layers or other surface treatments. During cleaning, in addition to the pretreatment, the surface of the body is cleaned by, for example, removing the adhering fat and / or oil in a degreasing process and / or other deposits such as rust and / or scale in the stain. The materials to be treated are preferably metallic materials and surfaces. In a preferred embodiment, the bodies are made of steel, galvanized steel, zinc, stainless steel and / or aluminum. In a particularly preferred embodiment, the body is made of steel or galvanized steel.

It is generally known that a turbulent movement of process fluids by means of pumps in the bypass or with the aid of the supply of air, compressed air and / or liquid via bottom lines in iron pickling basins can increase the pickling reaction speed and thus reduce the pickling time. The disadvantage of these systems, however, is that no and / or little fluid movement falls on the body parts located in the flow shadow. Another disadvantage of these systems is that large parts of the process basins are lost, for example due to the large turbines generating turbulent flows. This leads to a reduced loading capacity of the basins and / or to an enlargement of the basins, which is associated with a higher use of chemicals and larger process rooms. The supply of air, compressed air and / or liquid to the pickling basin can also lead to foaming of the process liquid, which can have negative qualitative and system-specific effects. The disadvantage of the systems described is therefore not only the high energy consumption, but also the increased need for chemicals, process fluid and / or space. In addition, the systems in the prior art do not allow the stain to move evenly. Further disadvantages are the diffuse and uncontrollable bath movements or flow orientations.

In order to achieve improved cleaning and / or pickling of the material and / or the body in the process basin, a laminar flow profile is generated in the present invention. The laminar flow profile when degreasing the surfaces and / or pickling improves degreasing performance as well the pickling process. In contrast to a turbulent flow profile, in laminar flows the liquid layers slide smoothly and evenly over one another, which means that no significant mixing processes occur. Such a flow flows around the body, ie the liquid moves symmetrically around the body, dividing in front of the middle of the body, flowing smoothly around the body and flowing back together after it. Due to the continuous flow of the liquid, a constant exchange is generated within the boundary layer between the body and the liquid, which leads to the removal of the "used" liquid and the supply of "fresh" liquid in the border area.

In the case of the flow profile according to the invention, despite the body in the process basin (pretreatment, degreasing or pickling), the entire volume of liquid is moved in the process basin, as a result of which the liquid is completely circulated and homogenized. Due to the constantly changing boundary layers in the transition area between the material (component) and the process liquid, for example in the pretreatment, degreasing bath or the pickling bath, saturation does not occur because fresh process liquid is always transported to the material surface of the body in the bath. The cleaning result is improved compared to the prior art, such as example 2, Fig. 3 and Tab. 1 can be seen. The at least one pump (8) per flow direction for generating the flow profile is attached to one side in the basin for surface cleaning of material surfaces of bodies, with only the pump or pumps being active for one flow direction. The flow profile is deflected at the end of the basin (end of the basin length), whereby the flow direction of the process liquid, compared to the cross section of the basin, is clockwise (to the right) or counterclockwise (to the left), as in Fig. 4 shown. The direction of flow is preferably described in terms of the movement of the process liquid within the basin in relation to the cross section of the long side of the basin. In order to obtain a complete coverage of the basin with a unidirectional flow, two or more pumps (8) interacting with one another are used, which support the same flow profile, for example "clockwise", as in FIG Fig. 4 a) or 4 b). The two interacting pumps (8) are preferably attached to the opposite end faces, with a first pump in the upper one Area near the surface on the front side and which a second pump is arranged near the pool floor, such as in Fig. 1, Fig. 2 and Fig. 4 shown. The diagonal arrangement of the two interacting pumps (8) leads to an increase in one direction of flow in each case, for example the clockwise flow in the bath. However, several pumps (8) interacting with each other can also be used per direction of flow in order to maintain or strengthen the flow profile in the same direction, for example the clockwise flow profile, or to largely avoid flow shadows on bodies in the bath (1).

In an embodiment with several pumps (8) per direction of flow, the pumps (8) are preferably each arranged in the edge regions of the end faces of the elongated basins. The operation of the opposite pumps for the opposite flow directions takes place in a reversing manner in order to generate a change in the flow direction. In order to minimize flow shadows as far as possible and to obtain an optimal alignment of the flow profiles, two or more pumps (8) per flow direction are preferably positioned crosswise on the end faces of the elongated basins. The pumps (8) located on one end face are positioned in such a way that one pump is arranged in the upper region of the basin and the second pump (8) is arranged in the lower region of the basin, see for example Fig. 1, 2 and 4th . Such an arrangement enables the formation of an opposing flow direction. In order to avoid turbulence as far as possible and to generate a laminar flow profile, in such an arrangement, as described above, the respective diagonally arranged, interacting pumps (8) are active on the end faces. The pumps with an opposite flow direction are inactive.

By additionally reversing the pump operation, ie reversing the direction of rotation of the pumps (8), the flow shadows that form on bodies in the basin can be compensated for or prevented. The same can also be done by activating the pump operation crosswise, as explained above. With the help of the described arrangement of the pumps and a reversal of the flow, targeted or controllable flow profiles can be generated that prevent saturation at the boundary layers of the body. A reversal of the The direction of flow is preferably offset in time, ie only after the movement of the flow, for example "clockwise", for example Figure 4a ) has almost come to a standstill, the opposite flow formation takes place "counterclockwise", as in Figure 4b ) shown. In one embodiment, the direction of flow is therefore changed within the at least one process bath. The direction of flow can be changed by reversing the direction of rotation of the pumps (8) and / or by activating the pumps (8) in the opposite direction, as explained above. The duration of the different flow directions and / or the change in direction depends on the dimension of the elongated process basin, its volume and / or the body in the process basin and the initial state of the components. In one embodiment, the duration of one flow direction is up to 20 minutes.In a preferred embodiment, the duration is up to 10 minutes; in a particularly preferred embodiment, the flow direction change takes up to 5 minutes. the pool length is preferably greater than the pool width. The flow profile according to the invention is deflected at the end of the basin (end of the basin length), as a result of which the laminar flow profile is retained in the device according to the invention and the associated method.

The basins for surface cleaning preferably do not require a separate inlet and / or outlet to produce the flow profile according to the invention. The pumps (8) are integrated directly into the basin, without making an expensive reconstruction of the basin and / or significantly reducing its volume.

The pumps (8) used to generate a flow according to the invention comprise at least one rectifier. The rectifier enables a laminar flow to be generated, in which the outflow velocity is equal to the flow velocity at the outlet of the pump (8). A high outflow speed with the rectifier of the pump (8) enables the flow profile to be maintained even within a certain range of the pump (8) without causing turbulence. At a certain distance, the flow profile therefore has approximately the same properties and approximately the same flow velocities as the flow at the outlet the pump (8). As already explained above, the term "approximately" indicates that in a confined or closed basin, the properties can differ slightly from the original flow, as there can be deflections due to walls, floor and / or other bodies do not change the essential flow form, ie flow velocity, flow direction and / or flow form of the whole. Additional abrasions of the housing and / or the rotor blades within the pumps can additionally increase the laminar flow profile and the range of the flow. In one embodiment, the flow rate of the pump used is 2 m / s to 6 m / s, preferably 3.3 m / s. The range of the pumps (8) used in closed systems and one-sided installation is in the range of 2 m to 20 m, preferably 2 m to 12 m, particularly preferably 9 m. The range in closed systems with two-sided installation of the pumps ( crossed, offset) is in the range from 2 m to 30 m, preferably 3 m to 25 m, particularly preferably 10 m to 18 m. The Reynolds number of the flow profiles created by the submerged components can be adjusted by the pump control. In a preferred embodiment, the Reynolds number can be regulated during the process. The Reynolds number in the basin for producing a flow according to the invention is dependent on the characteristic length, the dynamic viscosity and density of the liquid and the flow velocity. In one embodiment, the Reynolds number in unequipped basins is 2 × 10 ⁶ to 10 × 10 ⁶ .

In one embodiment, there is a heat exchanger (15) on and / or in the basin, which heats the process basin (1). In one embodiment, the flow can also be temporarily interrupted. During this so-called standing time, in which no or only a small flow is generated and the liquid is at a standstill or in slight movement, the contaminants on the surface and / or on the bottom of the basin can settle. In one embodiment, these contaminants, such as fats and / or oils on the surface of the liquid or other contaminants on the bottom of the basin, can be removed from the process basin by overflows, suitable suction devices, pumps and / or filters. Contaminants at the bottom of the basin are, for example, detached scale as hematite (Fe ₂ O ₃ ) or magnetite (Fe ₃ O ₄ ,), which accumulates and becomes can collect at the bottom of the pool. A regeneration cycle can also be operated in parallel to the actual production / cleaning cycle.

In one embodiment of the present invention, the flow is used for chemical surface treatment in degreasing baths. The basins can have any shape. The process basins preferably have a cuboid shape. The degreasing is preferably carried out as alkaline hot degreasing. Due to the use of laminar flow technology (8) in the degreasing bath, the demulsifying oils and / or fats cannot develop and / or accumulate on the entire surface of the basin. In a preferred embodiment, in addition to the at least one pump for producing the flow (8) according to the invention, there is a heat exchanger (15) for each direction of flow in the basin, which heats the basin to a corresponding temperature. The temperature here is preferably 50-70 ° C, particularly preferably 60 ° C. The fats and / or oils accumulate due to the current in the area of the narrow sides of the pool. The narrow sides of the pool are the front and / or back of the pool. These areas are usually not relevant to production, since there are heat exchangers (15) and / or overflows in these areas, which means that there is no product contact.

In one embodiment, an overflow (2) is provided on one of the two or on both narrow sides of the basin, ie the front and / or rear of the basin, or on all sides. The overflow (2) is preferably designed in such a way that contaminants located on the surface and / or on the bottom of the basin can be removed from the actual process bath, such as the degreasing bath. The overflow (2) can be mounted on the basin in an individually adjustable manner. The overflow (2) can also be coupled to a separate filtration circuit. This separate circuit enables floating fats and / or oils, which could interfere with the actual degreasing process in the process bath (1), to be extracted and removed. The removal of the contaminants that can settle on the ground can also be carried out with the aid of a pump circuit connected to the process circuit. The pump circuit can comprise any pump known in the prior art. The pump in the pump circuit is preferably a rotary lobe pump, a rotary lobe pump, a flap pump, a gear pump, an eccentric screw pump, a hose pump, a pneumatic diaphragm pump and / or a centrifugal pump. The pump is particularly preferably a centrifugal pump. In a preferred embodiment, the pump circuit has a filter (14). In one embodiment, the separation of the contaminants on the floor takes place parallel to the actual production or cleaning cycle. Due to the intensive flow profiles, possible settling pollutants are in suspension on the ground and can be removed by filtration. Appropriate cleaning prevents accumulation of sludge on the floor, which can interfere with the cleaning result of the components. In an alternative embodiment, separation can also take place without the above-described overflows and / or filtration, but with the aid of fat / oil separation devices, such as attachable and / or floating surface extractors, so-called skimmers (3). Oil separation devices are, for example, skimmers, ultrafiltration (crossflow), centrifuges, inclined plate clarifiers, decanters or osmosis units. The oil separation devices are not limited to the previous list, but can be any known separation device. However, these fat and oil separation devices can also be used in addition to the overflows and / or filters. The overflow (2) and / or the oil separation device (13) are preferably attached to the opposite side of the heat exchanger (8) where the oil and / or fat creams collect. With the help of the generated flow, which flows around the body to be treated from all sides, as well as the idle times and / or parallel regeneration times, an ideal degreasing result can be generated and the degreasing times significantly reduced, which leads to a corresponding reduction in costs and an increase in throughput. The filtration and / or oil separation described above can take place in the idle times in which no or little bath movement is generated or within the process in which the bath is moved by means of a laminar flow. In a preferred embodiment, the oil is separated off during the idle times. If the pumps are arranged on one side, the overflow is preferably arranged opposite the pump. If the pumps are arranged on both sides in the basin, the arrangement of the overflow is irrelevant. The depth and / or the height of the overflow is / are designed to be variable depending on the process basin. In a Embodiment, the at least one overflow has a depth which is below the bath surface.

In one embodiment, continuous builder and surfactant additions can be integrated in the bypass / filtration / oil separation circuit. So-called sawtooth profiles in the bath composition and / or concentration of the process bath are avoided. Sawtooth profiles are constantly changing conditions in the bath composition and / or concentration, which can strongly (negatively) influence the performance of the process baths. Possible builders are, for example, sodium hydroxide (NaOH) and / or potassium hydroxide (KOH). Surfactants for adjustment can include, for example, anionic, cationic and / or nonionic surfactants or mixtures thereof. Builders and surfactants for use in the indicated method and the associated device are not limited to the list above, but can include all substances known in the prior art with these properties or combinations thereof. With the help of the controlled additions, the cleaning or pickling result can also be checked.

In one embodiment, the process bath according to the invention is a demulsifying bath. In the demulsifying bath, breakdown agents are introduced into the process basin when a certain oil / fat content is exceeded and / or there are breakdown agents in the degreasing bath and / or the degreasing solution. In a preferred embodiment, the splitting agents are introduced into the basin (1) during periods of rest or standing. This enables a demulsifying and controlled oil / fat separation. The value of the oil and / or fat content in the pool is preferably below 3%. In a preferred embodiment, the oil and / or fat content in the process basin is below 1.5%. In a particularly preferred embodiment, the oil and / or fat content in the process basin is 0.3% to 0.5%. If this value is exceeded, a splitting agent, which can be an additive, is added to the process bath in the emulsifying bath (process liquid). The agent is preferably not added during the production process. The splitting agent can be any known means for separating oil and fat. Examples of such splitting agents are, but not limited to, mixtures of nonionic surfactants. In a preferred embodiment it is a mixture of different fatty alcohols. In a particularly preferred embodiment, these are mixtures comprising alpha-alkyl-omega-hydroxypoly (oxypropylene) and / or poly (oxyethylene) polymers in which the alkyl chain contains at least 6 carbon atoms (C6) and ethoxylated propoxylated C12-14 alcohols.

In one embodiment, the flow profile according to the invention can also be used in iron pickling (Fe pickling). The mode of operation and the structure are the same as those of the degreasing bath. In particular, the at least one basin for Fe pickling preferably has a cuboid shape in which at least one pump (8) is arranged per direction of flow in the area of one of the narrow sides of the basin. Heating the basin is optional due to the improved pickling effect. When the basins are heated, in one embodiment the pump can be on the same side as a heat exchanger (15). When the basin is heated (15), the temperature of the iron-pickling bath is between 15 ° C and 45 ° C. In a preferred embodiment, the temperature of the liquid in the basin is 20 ° C to 35 ° C. The narrow sides of the pool are the front and / or back of the pool. In a preferred embodiment, an overflow (2) is provided, its structure and possible combinations being analogous to the overflow of the degreasing bath. The flow according to the invention and corresponding circulation of the liquid comprising iron (Fe) in a hydrochloric acid (HCl) solution, enables the additional absorption of oxygen (O ₂ ) from the air and thus contributes to an additional formation of iron (III) ions ( Fe ³⁺ ). The iron (III) ion concentration leads to an increase in the pickling performance. In one embodiment, an additional introduction of air or oxygen is provided. The air or oxygen is introduced with the aid of at least one ventilation system (9), which can preferably also be combined with the flow pump (8). A controllable parallel air supply (9) enables an additional formation of Fe ³⁺ as well as a regulation of the pickling process. In a preferred embodiment, the at least one ventilation system (9) can therefore be controlled independently of the flow pump (8). With the help of this regulation, an optimal Fe ³⁺ production or regulation can take place within the basin. The optimum Fe ³⁺ content for the iron stain in the bath is 0.1 g / L to 10 g / L, preferably 0.3 g / L to 8 g / L, particularly preferably 0.5 g / L to 5.0 g / L. The pickling processes in the surface area known in the prior art show extreme and constantly changing stoichiometrically changing conditions in the bath composition, the so-called sawtooth profile. Corresponding pickling processes are carried out using ideal pickling curves, ie iron and hydrochloric acid (HCl) content, with an increased HCl concentration of, for example, 170 g / L and a corresponding initial iron concentration of, for example, 70 g / L. Due to the removal of material from the surface of the body, the process bath (1) is enriched with iron over the course of its service life, while the HCl concentration is reduced stoichiometrically. From a certain residual acid content, the pickling becomes ineffective due to the required extended pickling time, which can no longer be compensated for by corresponding increases in temperature even from a certain level. The old bath must then be appropriately disposed of and remade. The flow in the iron / hydrochloric acid pickling basin, which can be combined with a controllable additional air supply (9), considerably lowers the previously required hydrochloric acid concentration. In one embodiment, the HCl concentration is 40 g / L to 100 g / L, preferably 50 g / L to 80 g / L. In one embodiment, the used acid is removed from the process basin (1) and fresh hydrochloric acid is added to the system. The removal of used acid and the addition of fresh acid can be carried out continuously or discontinuously. Fe-pickling can therefore be used almost constant in the bath composition and concentrations and therefore have no or a significantly reduced sawtooth profile compared to the prior art. In a preferred embodiment, the content of hydrochloric acid and / or iron (III) ions in the process bath (1) is monitored by suitable systems. The used acid and fresh acid are preferably stored in corresponding buffer storage tanks / collecting tanks (5, 11). With the help of the method listed above, the pickling times can be significantly reduced compared to the state of the art. The degreasing and / or pickling times depend on various factors, such as the material, the processing condition and / or the degree of oxidation. In general, a reduction in the duration of treatment by 20% to 70% compared to the prior art can be observed, preferably by 30% to 50%. In the pickling basin, the flow profile formed leads to an equilibrium between iron (III) ions and iron (II) ions in the process bath. The equilibrium that is created at the interface between body and liquid leads to the formation of a protective layer and / or creation of an optimal cleaning state on the surface of the treated body, both of which lead to increased protection against corrosion, such as Fig. 3 and can be found in example 2.

The flow in the iron pickling basin, which can be combined with a controllable additional air supply (9), leads to the formation of a protective layer, a shift in the resting potential on the body and / or an ideal cleaning result, as well as a reduction in crystallization nuclei through the constant exchange of the liquid in the area of the boundary layer between the liquid and the corresponding body. This layer, shift of the resting potential and / or improved removal of foreign bodies means that the body does not show any or only slight reoxidation products even after prolonged outdoor exposure, see e.g. Example 2, Fig. 3 and Tab. 1. Subsequent process steps, such as the flux bath in the area of hot-dip galvanizing, can in some cases be dispensed with due to the protective layer that is created. Preliminary data from the surface examinations using cross-sections of reference samples and samples from a pickling process according to the invention show, using the example of galvanizing, that the subsequent surface refinement is smoother, more compact and more uniform compared to the prior art. In the case of zinc coating, for example, the bodies are free of voids and cracks according to the method according to the invention, in contrast to the samples treated in standing pickling (standing pickling, 30 min pickling time).

With iron pickling, due to the optimized flow profile, an equilibrium is formed at the boundary layer of bodies between iron (II) ions and iron (III) ions. The flow according to the invention enables the body in the process bath to be optimally wetted with process liquid, for example hydrochloric acid (hydrochloric acid, HCl) or other acid mixtures and / or oxidizing agents. The iron (III) ions formed at the boundary layer form an iron (III) hydroxide layer in subsequent steps, such as rinsing or a flux bath, which protectively surrounds the body, cause a shift in the resting potential and / or achieve a optimal cleaning result with a low number of recrystallization nuclei on the component surface. These effects occur with a ratio of iron (III) ions and iron (II) ions (Fe ³⁺ / Fe ²⁺ ) in the process bath of 0.1% to 5%. In a preferred embodiment, the ratio of Fe ³⁺ / Fe ²⁺ is 0.2% to 3%, particularly preferably a ratio of 0.3 to 1.5%. Alternatively, a rinse cycle after pickling can be activated. This has low Fe and / or HCl contents. The contents in an additional rinsing bath are below 5 g / L. In a preferred embodiment, the contents are 3 g / L, particularly preferably 1 g / L. This prevents a high proportion of iron or iron (II) ions and / or acid from being present and the carryover to the subsequent processes being reduced. However, the method according to the invention and the associated device lead to an optimal result in the treatment of the surface even without a downstream rinse. This ideal cleaning reduces foreign bodies on the objects to a minimum. The reduction of the foreign bodies and thus the elements that favor corrosion leads to a significantly minimized oxidation of the treated bodies, see e.g. Example 2, Fig. 3 and Tab. 1. This almost homogeneous surface also improves the subsequent processing of the body.

In a further embodiment, the flow in the process basin (1) can also be used for zinc pickling. With the help of the optimal movement of the liquid in the zinc pickle through the flow as well as an optional control of the suspended matter load and / or temperature, an optimal pickling result can be achieved that reduces the pickling times from the prior art by at least 20-70%, preferably by 30% to 50% . The stoichiometric ratios and processes are analogous to the Fe pickling. Here only Fe is replaced by Zn. The zinc pickling materials also have an extreme sawtooth profile in the prior art. The bath concentration is, for example, 160 g / l HCl and 0 g / l Zn. During the service life and intermittent additions of fresh acid, the bath becomes enriched with Zn, while the HCl concentration is reduced stoichiometrically. Above a certain residual acid content, pickling is also ineffective here and the bath must be disposed of and remade. The flow according to the invention considerably lowers the previously required hydrochloric acid concentration. In one embodiment, the HCl concentration is from 30 g / l to 80 g / l, preferably from 40 g / l to 70 g / l. In contrast to Fe pickling, zinc pickling does not add any additional air to the process bath (1), as this would lead to increased foaming and zinc (Zn) cannot be oxidized. The zinc pickling bath (1) contains the following ingredients: zinc (Zn) and hydrochloric acid (HCl). The zinc concentration in the process liquid is preferably a zinc (Zn) / iron (Fe) ratio of 8: 1. As in the previous process bath (1), in one embodiment the used acid can be removed from the process bath (1) and added by discontinuous or continuous addition of fresh acid. The zinc pickling solutions can thus be used in an approximately constant bath composition and concentration, analogous to the iron pickling materials, and therefore have no or a significantly reduced sawtooth profile compared to the prior art. With the help of the permanently reduced HCl content of the basin, the potential for the storage of hydrogen in the material decreases, which leads to the embrittlement of the metal (hydrogen embrittlement) and, in the worst case, to brittle fracture. Hydrogen embrittlement as described above can occur in every pickling process, ie for example in iron and zinc pickling, and is significantly reduced by the method described.

In one embodiment, the process basin during zinc pickling, due to the foam formation, comprises at least one overflow, preferably two overflows, as already described above. In order to reduce the increased foaming during zinc pickling and to prevent foaming and / or sloshing over, additional nozzles can be provided. These nozzles are arranged above the overflows and / or on or on the surrounding pool edges and spray liquid, preferably a process solution (here: zinc pickling), onto the foam that forms. This has the advantage that foam formation is reduced and the bath level of the process bath does not have to be reduced any further. Furthermore, no air supply is necessary.

With the help of flow technology (8) in the process baths for the pretreatment of surfaces of bodies, the pretreatment of the bodies can not only be shortened, but also the number of process baths previously required. Furthermore, previously known method sequences can be modified and / or varied. This leads to a considerable reduction in costs and a reduction in the use of chemicals and / or downstream input materials and a corresponding increase in production. In the case of surface pretreatment, for example hot-dip galvanizing, 6 to 8 pretreatment tanks with iron pickling are provided in the prior art. the Flow profiles according to the invention in the method and / or device in the process bath (1) enable these to be reduced to 3 to 4 basins. In one embodiment, the method using laminar flow technology enables the process baths for surface treatment to be reduced by at least 30%, preferably by at least 50%. By reducing the pickling bath surfaces, lowering the HCl concentrations and, if necessary, using a suitable emission inhibitor, the HCl emissions in the corresponding pretreatment areas / systems are significantly reduced. In a preferred embodiment, the emission is below 1 mg / m ³ HCl. The previous use of acid scrubbers is no longer necessary. On the contrary, with continued use of an acid scrubber, the relevant emission values at the chimney outlet would be higher than with a wind deflector fan. When using an acid scrubber, the values are 9 mg / m ³ , preferably 7 mg / m ³ , particularly preferably 5 mg / m ³ HCl. These values are further reduced by replacing known wind deflector fans and / or additional fresh air supply. The emission values can be reduced to ≤ 4 mg / m ³ HCl (exit wind deflector fan), preferably ≤ 2 mg / m ³ HCl (exit wind deflector fan), particularly preferably to ≤ 1 mg / m ³ HCl (exit wind deflector fan). The reduction of the hydrochloric acid concentration through the laminar flow technology in the process baths means that the developments in emission protection, which have replaced the earlier wind deflector fans through the use of an encapsulation with an acid scrubber, are reversed, since an acid scrubber is more ineffective in terms of process technology and more economically costly.

With the help of the method according to the invention and the associated device, waste materials as well as input materials are reduced to a minimum and an optimal degreasing and pickling result is achieved, whereby an optimized wetting condition is ensured, which can take into account the constantly increasing visual demands of end users / customers. The method according to the invention and the associated device also make it possible to dispense with any subsequent process baths, as a result of which any potential accident relevance is reduced.

The present invention therefore also relates to a device which comprises at least one degreasing bath and at least one bath for pickling, at least one of the Process baths comprises a flow device for generating a flow profile according to the invention. The device can also contain at least one rinsing bath. In a preferred embodiment, each process bath has at least one pump per direction of flow for generating laminar flow, the pumps being located within the basin and being arranged in the side area. In this context, inside the basin means the arrangement of the pumps in the process basin in direct contact with the process liquid, ie within the process liquid. The process baths can have any shape, but the baths preferably have a cuboid-like shape, at the end of which there is at least one pump for generating the laminar flow. As already shown above for the method, the two or more pumps (8) for the laminar flow can be attached on one side in the basin or on two opposite sides in the basin for the surface modification of material surfaces of bodies. In a preferred embodiment, two or more pumps per direction of flow are arranged in the basin. Here, one of the interacting pumps (8) is located on one of the two end faces, ie a pump is arranged on both narrow sides of the process basin, so that a flow direction is formed, ie either "clockwise" or "counterclockwise" compared to the Cross section of the bath. In order to obtain a rectified flow or flow direction, the two interacting pumps are preferably attached to the opposite end faces, one first pump being arranged diagonally in height to the one second pump on the opposite end face. This arrangement does not change the direction of flow, for example "clockwise", but maintains the already existing flow direction and / or strengthens it without changing the direction of flow, for example "counterclockwise" in the cross section of the basin, see for example Fig. 4 b) . In one embodiment, a plurality of pumps that interact with one another can also be arranged for each flow direction. In a further embodiment, in addition to the interacting pumps (8), there can also be pumps (8) located in opposite directions which reverse the direction of flow, such as the Fig. 4 a) and b) can be found. This change in the direction of flow, for example from clockwise to counterclockwise (in cross-section), enables flow shadows through bodies to be minimized. In this embodiment, each only the pump (8) is active for one direction of flow or the pumps (8) that interact with one another are active for one direction of flow, ie the pumps (8) that support the same direction of flow. The at least one pump (8) for the opposite flow direction is inactive during this time. In a preferred embodiment, at least two pumps (8) per direction of flow are arranged in the basin, the pumps that interact with one another are arranged diagonally to one another on the opposite end, as for example in FIG Figs. 1 and 2 shown. The at least two pumps (8) that work together and generate a flow with the same flow direction, for example "clockwise", for example Fig. 4 a) , are preferably active at the same time. If there are several pumps (8) for the same flow direction, however, only some of them can be in operation.

The pumps for generating the flow according to the invention are designed in such a way that the Reynolds number can be variably set. The Reynolds number in the basin for producing a flow according to the invention is dependent on the characteristic length, the dynamic viscosity and density of the liquid and the flow velocity. In one embodiment, the Reynolds number in unequipped basins is 2-10 x 10 ⁶ .

As already described above for the method, in one embodiment the device can have units for monitoring, determining and regulating parameters such as temperature, pH value, substance concentrations, among others. In a preferred embodiment, the process baths for degreasing and / or the pickling have monitoring mechanisms and regulating mechanisms which are used to determine, monitor and / or regulate the temperature and / or concentrations of the substances contained in the process bath liquid. In a particularly preferred embodiment, the temperature and the iron ion content in the iron pickling process basin are determined. The iron (III) ion content in the at least one process bath for iron pickling should be 0.1 g / L to 10 g / L, preferably 0.3 g / L to 8 g / L, particularly preferably 0.5 g / L to 5.0 g / L and / or a ratio of Fe ( ³⁺ ) / Fe ( ²⁺ ) of 0.1 to 5%, preferably 0.2 to 3%, particularly preferably 0.3 to 1 .5%.

In a further embodiment, the device comprises a device for removing fats, oils and / or contaminants from the at least one process basin. As already described for the method, the overflow and regeneration circuit can have different designs and variations, as shown above. In a preferred embodiment, when the at least one pump is mounted on one side, the overflow is located on one of the two end faces of the process basin opposite the heat exchanger. In addition to or instead of the overflow, at least one oil separation device can also be present. Possible oil separation devices are, for example, the elements described above.

In certain basins that tend to foam formation, nozzles can be arranged at the overflows and / or at or on the circumferential pool edges, into which liquid is pumped through suitable inflow lines Foam is distributed and reduces its formation.

These and other embodiments of the present invention are disclosed in and are encompassed by the specification and examples. Additional literature on known materials, methods, and applications that can be used in accordance with the present invention can be obtained from public libraries and databases using, for example, electronic devices. A more complete understanding of the invention can be obtained by referring to the following examples, which are provided for the purpose of illustration and are not intended to limit the scope of the invention.

Examples Example 1: Process for the ideal pretreatment of surfaces

The process steps of the optimized surface pretreatment of metallic bodies, preferably made of steel, include the steps of degreasing (a); rinsing (b), the solution from (a) being prevented from being carried over into the following process steps; iron pickling (c); a further rinsing process (b); and, if necessary, a subsequent zinc pickling and / or flux bath (d). The degreasing stage (a) is used to remove organic contaminants. The in Fig. 1 The degreasing process shown together with the device with laminar flow enables an almost complete removal of organic substances, in particular grease and oils. Unlike stationary or turbulent baths, the laminar flow in the process bath (1) flows around the body and thus reaches all parts of the body. The fat and / or oil separated from the body can be removed from the bath through an overflow (2) on the process bath (1) and thus increase the effectiveness of the degreasing process. The separated fat and / or oil can be used as in Fig. 1 also be collected in a container (5). The container (6) is a calming container that only has a reduced / slowed movement and / or flow so that the fat and / or oil settle on the surface and can be separated off as a concentrate by a surface suction device (3), for example a disc skimmer. This is collected in a suitable collecting container (5) for disposal. The cleaned process liquid remaining in the container (6) can be returned to the process basin (1) through an additional line. Possible settling soil substances can be removed by filtration (14). This regeneration cycle enables an optimized degreasing of the body as well as a return of the process liquid into the process basin (1), whereby less input chemical is used.

In the subsequent pickling stage (c), which follows the rinsing process (b), oxidic contaminants are removed from the body surface, the removal taking place in an acidic process bath. In the iron pickling baths described in the prior art, as a rule 6 to 8 iron pickling baths are required to remove the impurities from the bodies. In the in Fig. 2 illustrated method according to the invention with laminar flow technology (8) is the in Process basin (1) is bathed in the body by the moving liquid and leads to an optimal pickling result, whereby only 3 to 4 pickling baths are used. An additional supply of air or oxygen (O ₂ ) (9) on the liquid surface and / or the pump (8) leads to an increase in the Fe ³⁺ concentration in the process liquid of the basin (1), which causes an improved pickling effect . Any oil and / or fats that can settle on the surface of the liquid during the pickling process can also be removed from the process basin through an overflow (2) and / or other oil separator (13). The system of oil or fat separation from the process bath can be carried out analogously to the system in degreasing (a). As in Fig. 2 is shown, the iron pickling process liquid can also be removed in the form of old pickling (12) and stored in a collecting container (5). Fresh acid can be introduced into the process bath from a storage container (11) parallel to the removal.

In the prior art, for example in the hot-dip galvanizing process, bodies that are to receive a zinc coating also go through an additional flux bath (d) as a pretreatment stage. The purpose of this bath is to protect the body from flash rust / corrosion on the way to the drying process as well as the actual galvanizing process (see zinc melt). Due to the optimal degreasing and / or iron pickling by means of the laminar flow technology, a treatment of the body for the further surface modification is unnecessary, a simple rinsing (b) is sufficient in the method according to the invention to keep the concentration of impurities in the subsequent processes low, so that these do not lead to a loss of quality in further treatment.

Example 2: Treated surface according to the method according to the invention

In aging studies in which pretreated metal bodies were exposed to the weather for different lengths of time, clear differences in the strength of the corrosion were found. For this purpose, bodies which had been treated according to the state of the art (reference: stand pickle; pickling time 90 min) and bodies which had been treated by the laminar pretreatment system for 5, 10, 15 or 30 minutes were compared with one another. The conditions were 1.2 g / L Fe ³⁺ ± 0.5 g / L Fe ³⁺ . Again Fig. 3 and Tab. 1 shows, bodies that were degreased and pickled with the help of the laminar process showed a significantly lower reoxidation process during outdoor weathering than bodies that were pretreated with the methods known in the prior art. Severe corrosion of the bodies, which were pretreated for 90 min (reference sample) according to the prior art method, could already be determined shortly after the outdoor exposure, in contrast to the bodies, which were each for 5 min, 10 min, 15 min, or were treated for 30 min with the method according to the invention. As can be seen in Tab. 1 the experiment could use the inventive method and of the device after 30 min in an iron-stain with 1.2 g / L Fe ³⁺ ± 0.5 g / L Fe ³⁺ any disruptive Soiling is removed from the body and a protective layer, a shift in the resting potential and / or an ideal, almost contaminant-free surface condition is generated, which largely prevents or minimizes a reoxidation process. Tab. 1 Corrosion statistics for outdoor exposure 5 min 10 min 15 minutes 30 min Reference (90 min) day 1 ++ + + - +++ Day 21 +++ +++ ++ + +++ - No visible corrosion
+ Slight corrosion
++ Medium corrosion
+++ Severe corrosion

Claims (10)

1. A method for the chemical surface treatment of bodies, wherein a laminar flow within the liquid in at least one process basin (1) for degreasing and/or for pickling is generated by at least one flow pump (8) with rectifier arranged per flow direction within the process basin (1), wherein at least two flow directions are generated in the process basin and wherein furthermore the at least one flow pump (8) per flow direction is arranged in the front region of the process basin (1) and only the at least one pump (8) each is active for a flow direction.
2. The method according to claim 1, wherein at least two interacting pumps (8) for generating a flow direction are arranged in the process basin (1), wherein the interacting pumps (8) each are diagonally arranged on the opposite end faces of the process basin (1) and generate an equidirectional flow.
3. The method according to claim 1 or 2, wherein the flow generates a liquid exchange at the interface between body and liquid.
4. The method according to any of claims 1 to 3, wherein during iron pickling the content of iron(II) ions can be reduced and the content of iron(III) ions can be increased by a controllable regulation, wherein the regulation of the iron content in the process bath preferable is effected via a controllable supply of air and/or oxygen.
5. The method according to any of claims 1 to 4, comprising

   a) a monitoring of the temperature, the pH value and/or the substance concentrations;

   b) a regulation of the temperature, the pH value and/or the substance concentrations; and/or

   c) an overflow, a grease/oil separation unit and/or a filtration.
6. A device for the chemical surface treatment of bodies by the method according to any of claims 1 to 5, comprising at least one process basin (1) with process liquid and at least one pump (8) with rectifier arranged per flow direction within the process basin (1) for producing a laminar flow, wherein the pumps (8) are arranged in the front region of the process basin (1) and wherein furthermore at least two flow directions are generated in the process basin (1).
7. The device according to claim 6, wherein at least two interacting pumps (8) for generating a flow direction are arranged in the process basin (1), wherein the same are each arranged on the opposite end faces of the process basin (1) diagonally relative to each other.
8. The device according to claim 6 or 7, wherein the device comprises

   a) at least one degreasing bath; and

   b) at least one bath for pickling.
9. The device according to any of claims 6 to 8, wherein the device comprises

   a) a monitoring of the temperature, the pH value and/or the substance concentrations;

   b) a regulation of the temperature, the pH value and/or the substance concentrations; and/or

   c) at least one overflow, a grease/oil separation unit and/or a filtration.
10. The device according to any of claims 6 to 9, wherein the device comprises at least one rinsing bath.

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