DE3802851C1 - Method of recovering paints and lacquers from the circulation water of paint shops, in which the paint or lacquer is taken up by the circulation water as overspray and/or drip loss - Google Patents

Abstract

In addition to solvents, binders, pigments, fillers and auxiliaries, the paint or lacquer may also contain solid and/or gelatinous impurities and chemical and/or physical coagulants and forms with the circulation water a mixture having a water content of not more than 50%. In order to recover paints and lacquers from this paint shop circulation water, the water inclusions present in the mixture are broken up in a turbulent mixer and removed from the mixing space. The mixture, which has been reduced to a water content of at most 10%, is subsequently converted into a flowable state by addition of up to 40% by weight of organic solvent or solvent mixture. Further solvent is added in a separate stirred tank. After coarse dirt particles have been screened out, the mixture which has been dewatered and diluted in this way is finally freed from the remaining impurities and any coagulants present, from partially gelled binders and from some of the fillers and possibly pigments in the centrifugal field of a one-step separation process at a maximum centrifugal acceleration of 200,000 m/s<2>, so that it is subsequently ... [lacuna] as base material for original finish formulations ... Original abstract incomplete.

Description

The invention relates to a method for the recovery of Varnishes and paints from the circulating water from Lackier plants, in particular paint booths, the paint or Paint color as overspray and / or drip loss from the circulation water is absorbed, in addition to solvents, binders, Pigments (for paint colors), fillers (for paint colors) and Auxiliary materials, if applicable, also solid and / or gel-like contaminants cleaning and chemical and / or physical coagulation contains medium and with the circulating water a mixture with up forms fifty percent water content.

Attempts have been made for a long time both (colorless) varnishes and (pigmented) varnishes to recover colors, on the one hand, the raw material costs when painting and on the other hand the environmental impact reduce pollution by depositing paint sludge. This was due to improvements in control automatic painting systems the emergence of overspray and Drip losses can be significantly reduced. With the DE-PS 35 16 881 was also a process for the recovery of Recyclable sludge materials suggested with which achieved should be that especially valuable materials with high reuse worth buying, such as binders and film formers mechanical separation processes are to be recovered.

The aim of the invention is to create it to avoid such paint sludge and paint or varnish colors directly from the circulating water of paint shops, especially to recover paint booths.  

In such painting systems, the overspray is first through which the cabin diagonally or vertically downwards flowing air added. The one loaded with paint particles Air is then sucked through a water curtain, where those due to small flow cross-sections high speeds for high turbulence and thus for an intensive mixing of water, air and overspray to care. The overspray that passes into the water becomes usually with the help of chemical and / or physical Coagulants that are added to the water are detackified, to avoid sticking in the water-bearing systems.

Part of the drip loss that occurs during the painting process wise gelled binder goes directly into the water is circulated as so-called circulating water. In this cycle is usually a calming zone so-called sewage lake, built in, from the overspray and drip losses can be removed.

The material discharged from such a sewage lake provides a mixture of solvents (e.g. aliphatic and cyclic hydrocarbons, alcohols, esters, ethers), Binders (e.g. alkyd, melamine, urea, Polyester, acrylic resins and their combinations), pigments (e.g. titanium dioxide, phthalocyanines), fillers (for example barium sulfates, calcium carbonates, Silicates) and auxiliaries (e.g. wetting agents and Leveling agents) and from gelled binder particles, solid contaminants, chemical and / or physical Coagulants and up to 50% water. So far this mixture is stored in hazardous waste landfills or in Hazardous waste incinerators made harmless, though the mixture to a high percentage from the original raw materials formulated in the paint or paint color  stands, however, by the presence of fused Binder particles, solid contaminants as well chemical and / or physical coagulants and Water have become unusable.

To achieve the goal outlined above the invention has for its object a method for Rückge recovery of paints and paint colors from the circulating water of To create painting systems that allow the annoying To largely remove components of the mixture and the Separate paint raw materials in such a way that the largest possible Share in the production process can be attributed.

The solution to this problem by the invention is characterized in that the What contained in the mixture inclusions in a turbulent mixer and be removed from the mixing room, that except for a what content of a maximum of ten percent dewatered mixture closing by adding up to forty percent by mass organic solvent or solvent mixture in one flow transferred and in a separate stirred container by further addition of organic solvent or solvent medium mixture to a viscosity of 30 to 100 seconds Flow time according to DIN 53211 from a DIN cup No. 4 ge is brought and that this dehydrated and diluted mixture finally after screening out coarse dirt particles in the Centrifugal field of a one-step separation process with a Centrifugal acceleration of up to 200,000 m / s² from the remaining impurities and any existing coagulation agents, from gelled binders and part of the Fillers and possibly pigments are freed.

The invention creates for the first time in practical everyday life drove feasible process with which paints and varnish paints from the overspray and drip loss in the circulating water from  Paint shops recovered and after removing the water inclusions and the impurities as a base material for New paint formulations can be used. To carry out of the method according to the invention are indeed commercially available Machines and apparatus used, the turbulent mixer but not for mixing for the first time, i. H. for comparison at least two solid or liquid substances are used instead of a kneader for dewatering one pasty, water-containing mass.

According to a further feature of the invention, the water not only in batches, but also continuously from the Mixing room of the turbulent mixer are withdrawn.

Furthermore, the invention proposes that organic solvents or solvent mixtures that are used for guiding the dewatered mixture into a flowable inlet used, the turbulent mixer at about 20% at low and add about 80% at higher turbulence to one Fast and even flowability in the turbulent to achieve the existing mixture.

In a preferred embodiment of the invention water-containing mixture by means of a screw conveyor in the Turbulent mixer entered. This will disrupt the supply of the mixture to the turbulent mixer avoided.

The method according to the invention is then intended to be based on a Embodiment using drawings he to be refined. From the drawings shows

Fig. 1 is a process flow diagram of an exemplary embodiment of a game system for performing the inventive method it,

Fig. 2 shows a schematic longitudinal section through a guide, for example from a Turbulentmischers,

FIGS. 3 to 8 each show a cross section along the section line AA through the turbulent mixer, with different phases of the dewatering process being shown.

The process flow diagram according to Fig. 1 shows a by a motor driven screw 1 a conveyor 1, which is supplied with the coming out of the circulation water of a painting installation, not shown, mixture G from overspray, drip loss and water. This mixture G is introduced by means of the screw conveyor 1 into a turbulent mixer 2 , which is also driven by a motor 2 a and is shown in a schematic longitudinal section in FIG. 2.

As can be seen from this longitudinal section in FIG. 2, the turbulent mixer 2 comprises a cylindrical housing 21 in which a shaft 22 driven by the motor 2 a is rotatably mounted. On this shaft 22 a plurality of paddles 23 are attached, which protrude into the mixing space 24 , which is formed by the housing 21 ge. On the top of the housing 21 there is a cover 26 provided with a filling shaft 25 . In the exemplary embodiment, a plurality of closable emptying openings 27 are provided in the lower part of the housing 21 .

The cross section shown in FIG. 3 along the section line AA through the turbulent mixer 2 shows a first phase with the shaft 22 at a standstill and housing 21 filled to about 60% with water-containing mixture G. The mixture has room temperature. As the enlarged representation of an excerpt from the mixture G below FIG. 3 shows, this mixture G consists of overspray plus drip loss O + T with more or less regularly distributed water inclusions W.

Fig. 4 shows a second phase, in which the shaft 22 rotates at 100 to 300 revolutions per minute. Due to the centrifugal force generated in this way, the mixture G was evenly distributed in the mixing chamber 24 and hurled against the cylindrical walls of the housing 21 . The enlarged section below again shown in FIG. 4 shows that in this phase the mixture G has been closed into individual particles on the one hand from overspray and drip losses O + T and on the other hand water W and that the water begins to move radially outwards .

In the third phase shown in FIG. 5, the shaft 22 continues to rotate at a speed between 100 and 300 revolutions per minute, the content of the turbulent mixer 2 has assumed a temperature of 30 to 40 ° C. The water W has - as can be seen in particular from the enlarged illustration below FIG. 5 - shifted radially outwards and is already essentially separated from the overspray and dripping loss O + T. This separation has intensified in the fourth phase according to FIG. 6. While the shaft 22 still rotates at 100 to 300 revolutions per minute and the temperature in the turbulent mixer 2 has risen to 40 to 70 ° C, the water W is on the inner wall of the cylindrical housing 21 , whereas overspray and drip losses O + T have accumulated in the central area around the shaft 22 . On reaching this phase, Fig 4 the emptying openings are in accordance. 6 27 opened once or several times, so that according to the arrow display in the lower part of FIG. 6, the water W can exit from the turbulent mixer. 2

After the last closing of the discharge openings 27 according to FIG. 7 (fifth phase), organic solvent or solvent mixture L is added to the dewatered mixture G of overspray and drip losses O + T through the feed shaft 25 in order to convert the mixture into a flowable state. The addition of this organic solvent or solvent mixture L can be up to 40 percent by mass of the dewatered mixture. The addition can be about 20 percent at a low and about 80 percent at a higher degree of turbulence of the turbulent mixer 2 , for which purpose the speed of the shaft 22 is changed accordingly. As a result, the mixture of overspray and drip loss O + T , which has been dewatered to a water content of at most 10 percent, is converted into a flowable state, which is shown in phase six in FIG. 8 after the motor 2 a of the turbulent mixer 2 has been switched off .

The mixture dewatered by the shear forces of the paddles 23 and converted into a flowable state by adding organic solvent and solvent mixture L is now continuously withdrawn from the turbulent mixer 2 as shown in FIG. 1 and fed to one or more separate stirring vessels 3 , the agitators of which in turn are each driven by a motor 3 a . The Ver drive flow diagram in Fig. 1 shows that for the same solvent medium tanks 4, from which the solvent or solvent L the turbulent mixer 2 was fed mixture, further solvent or solvent mixture L the mixing vessels 3 is supplied, so that the viscosity of the dehydrated mixture an Value reached that corresponds to a 30 to 100 second run-out time according to DIN 53211 from a DIN cup No. 4.

The dewatered and diluted to the desired viscosity mixture is then fed to a sieve 5 , through which coarse dirt particles are sieved. Thereafter, the correspondingly cleaned mixture reaches a single-stage centrifuge 6 driven by a motor 6 a , in which it is subjected to a centrifugal acceleration of a maximum of 200,000 m / s². As a result, the mixture is freed from the remaining impurities and any coagulants present, from gelled binders and part of the fillers and possibly pigments. After these impurities V have been withdrawn from the centrifuge 6 , the material recovered from overspray and drip loss O + T can be used as the base material B for new paint formulations.

Reference symbol list

1 - screw conveyor
1 a - motor
2 - Turbulent mixer
2 a - motor
3 - stirred tank
3 a - motor
4 - solvent container
5 - sieve
6 - centrifuge
6 a - engine
21 - housing
22 - wave
23 - paddle
24 - mixing room
25 - feed chute
26 - cover
27 - drain opening
B - base material
G - mixture
L - solvent or solvent mixture
O + T - overspray plus drip loss
S - dirt particles
V - impurities
W - water

Claims (4)

1.Procedure for the recovery of paints and lacquer paints from the circulating water of paint shops, in particular paint booths, the paint or lacquer paint being absorbed by the circulating water as overspray and / or drip loss, in addition to solvents, binders, pigments (for paint colors), fillers and auxiliaries optionally also contains solid and / or gel-like impurities as well as chemical and / or physical coagulants and forms a mixture with up to fifty percent water content with the circulating water, characterized in that the water inclusions contained in the mixture are broken down in a turbulent mixer ( 2 ) and be removed from the mixing room,
that the mixture, dehydrated to a water content of at most ten percent, is then converted into a flowable state by adding up to forty percent by mass of organic solvent and in a separate stirred container ( 3 ) by adding organic solvent or solvent mixture to a viscosity of 30 to 100 Seconds of expiry time according to DIN 53211 is brought out of a DIN cup No. 4
and that this dewatered and diluted mixture from the final sieving of coarse dirt particles in the centrifugal field of a one-step separation process with a centrifugal acceleration of a maximum of 200,000 m / s² of the remaining impurities and any coagulants present, of gelled binders and part of the fillers and possibly Pigments is freed. 2. The method according to claim 1, characterized in that the water is continuously withdrawn from the mixing chamber of the turbulent mixer ( 2 ). 3. The method according to claim 1 or 2, characterized in that the organic solvent or solvent mixture for converting the dewatered mixture into a flowable state to about 20% at low and about 80% at a higher degree of turbulence, the turbulent mixer ( 2 ) is supplied. 4. The method according to claim 1, characterized in that the water-containing mixture is introduced into the turbulent mixer ( 2 ) by means of a screw conveyor ( 1 ).