Method and apparatus for cleaning and reusing wash water prior to a sorting process of plastic and / or metal waste

Abstract

The present invention relates to a method and an apparatus for cleaning wash water originating from a sorting process of plastic and / or metal waste, comprising the steps of: washing the plastic and / or metal waste with wash water in a washing installation, collecting the wash water originating from the washing in a collection tank, and cleaning wash water originating from the collecting in a cleaning installation, wherein cleaning the collected wash water comprises the step of screening, wherein during the screening contamination is separated from the collected wash water, wherein screened wash water is collected in a first decantation tank, wherein the screened wash water collected in the first decantation tank is decanted from the first decantation tank, and wherein cleaned wash water is reused during the step of washing the plastic and / or metal waste with wash water.

Description

[0001] METHOD AND APPARATUS FOR CLEANING AND REUSING WASH WATER PRIOR TO A SORTING PROCESS OF PLASTIC AND / OR METAL WASTE

[0002] TECHNICAL FIELD

[0003] The invention relates to a method in the first aspect and an apparatus in the second aspect, both for washing, collecting, cleaning and reusing wash water originating from a sorting process of plastic and / or metal waste. The invention relates in particular to the use of the method and / or the apparatus for cleaning and reusing wash water originating from a processing process of plastic and / or metal waste, wherein the waste originates from automotive shredder residue, waste electrical and electronic equipment or from incinerator bottom ash.

[0004] PRIOR ART

[0005] EP3624960B1 describes a method for removing organic and inorganic harmful substances from waste with more than 20% biogenic content via wet mechanical separation, acidic washing with sulfuric acid, sulfate precipitation of heavy metals and anaerobic digestion without biological pretreatment or recycling of press water. The present invention does not describe what the additional problem of foam formation is for the remainder of the processes.

[0006] The invention of BRPI0609465 relates to a process for fragmenting and purifying plastic waste, in particular mixed plastic waste (MKS). The process comprises processing flakes and / or thick-walled plastic components obtained from sheet offcuts or fragmented sheet remnants into shavings, which are compacted into a compact product, in particular a particleboard. This compact product is subsequently fed into a disc grinder or drum grinder and ground therein in the presence of water, wherein the compact material is reduced in size in the grinder by at least ten percent. From the ground material leaving the grinder, a fine-grained fraction is subsequently removed. The remaining ground material is thereafter washed or mechanically dewatered and dried, or ground again in the presence of water in a second grinding step and subsequently dewatered and dried. Agents that reduce foam cause a reduction of foam but a higher amount of organic components in the water.

[0007] In the current prior art, various methods and apparatuses are applied to recover wash water after washing plastic and / or metal waste. Typically, the plastic and / or metal waste is washed to remove contamination such as glue, sand, fibers, and other unwanted substances. This is necessary to be able to efficiently perform a subsequent sorting step. The wash water used herein can be reused after a series of filtration and purification processes. Usually, the wash water is passed through screen or filter systems to remove solids, after which chemical and / or biological treatments can follow to remove dissolved contaminants. The cleaned wash water is subsequently reused in the process, which reduces water consumption and costs. Biological and / or chemical treatments make the cleaning of the wash water more complex because the wash water must be treated under specific parameters and usually for a long time. Furthermore, there is a need for additives such as detergents, bacteria, flocculants or anti-foaming agents, which are preferably used as minimally as possible. These known methods and apparatuses have as an important disadvantage that they are not suitable for cleaning and reusing wash water originating from heavily contaminated waste, such as waste originating from automotive shredder residue, waste electrical and electronic equipment or in particular incinerator bottom ash.

[0008] The current invention aims to find at least a solution for some of the abovementioned problems or disadvantages.

[0009] SUMMARY OF THE INVENTION

[0010] In a first aspect, the current invention relates to a method according to claim 1.

[0011] This method has, among others, the advantage that the cleaning and reuse of wash water from the washing of plastic and / or metal waste prior to a sorting process offers an improved circularity of the wash water. This helps to reduce the environmental impact and need for water as a raw material. Furthermore, the use of additives such as detergents, bacteria, flocculants or anti-foaming agents is minimized by the above method. Preferably, the method serves for plastic and / or metal waste originating from ASR (automotive shredder residue), WEEE (Waste Electrical and Electronic Equipment) or incinerator bottom ash, wherein a large variety of contamination can be present in the wash water. The large variety and strongly fluctuating degree of contamination can be easily accommodated by the method described in this document.

[0012] Preferred embodiments of the method are presented in claims 2 to 8. In a second aspect, the current invention relates to an apparatus according to claim 9.

[0013] This apparatus has, among others, the advantage that the apparatus for cleaning and reusing wash water from the washing installation for washing plastic and / or metal waste prior to a sorting process offers an improved circularity of the wash water. This helps to reduce the environmental impact and consumption of water as a raw material. Preferably, the apparatus serves for plastic and / or metal waste originating from ASR, WEEE or incinerator bottom ash, wherein a large variety of contamination can be present in the wash water. The large variety and strongly fluctuating degree of contamination can be easily accommodated by the first decantation tank and collection tank as described for the apparatus.

[0014] Preferred embodiments of the apparatus are described in dependent claims 10 to 17.

[0015] In a third aspect, the current invention relates to a use according to claim 18.

[0016] This use results in an advantageous separation of contamination in the wash water for waste streams originating from ASR, WEEE or incinerator bottom ash.

[0017] DESCRIPTION OF THE FIGURES

[0018] Figure 1 shows a flow diagram of a method according to an embodiment of the present invention.

[0019] Figure 2 shows a flow diagram of a method according to another embodiment of the present invention.

[0020] Figure 3 shows a flow diagram of a method according to a further embodiment from Figure 2.

[0021] Figure 4A shows a perspective view of a washing drum according to an embodiment of the present invention.

[0022] Figure 4B shows a detailed representation of a spiral comprised in the washing drum from Figure 4A. DETAILED DESCRIPTION

[0023] Cleaning and reusing wash water from the washing of plastic and / or metal waste prior to a sorting process offers various advantages, including an improved circularity of the wash water, a lower environmental impact, a reduced load of any further biological or physicochemical water treatment and a lower economic cost. Preferably, the method serves for plastic and / or metal waste originating from ASR (automotive shredder residue), WEEE (Waste Electrical and Electronic Equipment) or incinerator bottom ash, wherein a large variety of contamination can be present in the wash water. The large variety and strongly fluctuating degree of contamination in the wash water can be easily accommodated by the method and the apparatus described in this document.

[0024] Unless otherwise defined, all terms used in the description of the invention, including technical and scientific terms, have the meaning as commonly understood by a person skilled in the art to which the invention pertains. For a better understanding of the description of the invention, the following terms are explained explicitly.

[0025] "A", "an" and "the" refer in this document to both the singular and the plural unless the context clearly implies otherwise. For example, "a segment" means one or more than one segment.

[0026] The use of "first," "second," "third," and so on before a term does not indicate order, but merely serves to indicate a difference between several of the same umbrella term.

[0027] Quoting numeric intervals by the endpoints includes all integers, fractions, and / or real numbers between the endpoints, including those endpoints.

[0028] In the context of this document, "wash water" is a term for water that is used during the washing of plastic and / or metal waste in a washing installation. The wash water undergoes cleaning steps before it is reused for the washing of plastic and / or metal waste, whereby wash water can comprise different compositions and / or degrees of contamination. These different compositions and / or degrees of contamination are indicated with adjectives added to the term "wash water". Furthermore, "contamination" comprises, among others, fibers, sand and particles. In a first aspect, the invention relates to a method for cleaning wash water prior to a processing process of plastic and / or metal waste.

[0029] Preferably, the processing process of the plastic and / or metal waste is a sorting process.

[0030] The method comprises the steps of: washing the plastic and / or metal waste with wash water in a washing installation, collecting the wash water originating from the washing, and cleaning wash water originating from the collection.

[0031] In an embodiment, cleaning the collected wash water comprises the step of screening. During the screening, contamination is separated from the collected wash water. Screened wash water is collected in a first decantation tank. The screened wash water collected in the first decantation tank is decanted from the first decantation tank.

[0032] In an embodiment, the wash water originating after cleaning is reused in the step of washing the plastic and / or metal waste.

[0033] Cleaning and reusing wash water from the washing of the plastic and / or metal waste prior to a sorting process offers various advantages, including an improved circularity of the wash water, a lower environmental impact, a reduced load of any further biological or physicochemical water treatment and a lower economic cost. This helps to reduce the environmental impact and need for water as a raw material.

[0034] In an embodiment, the step of screening comprises a sub-step, wherein the collected wash water is screened by means of a first screen. The first screen removes fibers and solid particles from the collected wash water. To this end, the collected wash water passes through pores of the first screen. The fibers and the solid particles are retained by the first screen. The fibers and the solid particles are separated from the first screen.

[0035] Removing the fibers and the solid particles from the collected wash water ensures that contamination with an aspect ratio greater than one and with a smallest crosssection greater than the pores of the first screen are removed from the screened wash water. The fibers and the solid particles can originate, among others, from granulating plastic and / or metal waste, wood fibers, textile fibers, copper wires, and the like which come, among others, from ASR, WEEE or incinerator bottom ash. Removing the fibers and the solid particles ensures fewer to no obstructions during further cleaning of the collected wash water.

[0036] In an embodiment, the first screen is a drum screen. The collected wash water is introduced into the drum screen through an inlet and pressed from a core of the drum screen through pores of the screen against a shell of the drum screen. Preferably, the screened wash water flows along the shell where the screened wash water is collected.

[0037] The drum screen is advantageous as a first screen due to the tangential filtration through the first screen. The change of flow at the screen surface of the first screen ensures that there is no build-up of contaminants at the screen surface and the screening capacity is maintained. Preferably, an outer side of the screen surface is cleaned by means of spray nozzles, more preferably under high pressure. Furthermore, due to the tangential filtration, the fibers and the solid particles orient themselves rather transversely relative to the screen surface of the first screen, whereby they are separated better. Alternatively, a vacuum drum filter can be used as a first screen.

[0038] In an embodiment, the fibers and the solid particles are transported out of the first screen by means of spirals. The spirals are preferably positioned against the shell of the drum screen. The drum screen is preferably rotated, whereby the fibers and the solid particles are transported by the spirals to an end of the drum screen opposite to the inlet.

[0039] In an embodiment, an anti-foaming agent is added prior to the first screen. This prevents foam formation from causing the overflowing of one or more decantation tanks.

[0040] In an embodiment, the step of screening comprises a sub-step, wherein particles with a higher density than water are separated from the collected wash water. Preferably, the collected wash water is fiber-free. To this end, this embodiment can be advantageously combined with a previously described embodiment wherein the collected water is screened by means of a first screen. This is advantageous because as a result the fibers and the solid particles do not disturb the separation of said particles. Said particles are for example sand or other sediments. The wash water from which said particles have been separated is collected in the first decantation tank.

[0041] Removing the particles from the collected wash water ensures an increase in purity of the wash water. Furthermore, it reduces abrasion on the washing installation caused by the particles during the washing, whereby the washing installation exhibits less wear and whereby less maintenance is also necessary. Furthermore, removing the particles prevents wear on pumps or other components within an apparatus. Furthermore, the particles will not be reintroduced into the washing installation, whereby no concentration increase of the particles occurs.

[0042] In a further embodiment, the separated particles are screened by means of a second screen for separating remaining wash water from the separated particles. The remaining wash water is collected in the first decantation tank. This is beneficial because it allows a larger portion of wash water to be reused, thereby reducing total water consumption.

[0043] In an embodiment, the particles with a higher density than water are separated from the collected wash water by centrifuging, preferably by a hydrocyclone. Said particles with remaining wash water are discharged onto the second screen through a discharge at the bottom of the hydrocyclone. The wash water from which the particles have been separated flows along an overflow of the hydrocyclone to the first decantation tank.

[0044] By centrifuging, preferably by hydrocyclones, large flow rates can be processed efficiently at a high speed. Furthermore, the maintenance of hydrocyclones is generally simple because they contain no moving parts. Moreover, hydrocyclones can handle a large range of flow rates. As a result, the hydrocyclone can handle a large difference in contamination with particles in the collected wash water.

[0045] In an embodiment, remaining wash water is separated from the plastic and / or metal waste by means of a third screen. The remaining wash water is carried out of the washing installation by the plastic and / or metal waste. The remaining wash water runs through the third screen. The plastic and / or metal waste is transported over a screen surface of the third screen. Preferably, the third screen is a vibrating screen. More preferably, the vibrating screen comprises two compartments with a different vibration frequency for the two compartments. By means of the third screen, as much wash water as possible is recovered. The recovered wash water is combined with the collected wash water.

[0046] In a preferred embodiment, screened wash water from the first decantation tank flows into a second decantation tank. From the second decantation tank, the cleaned wash water is reused for washing the plastic and / or metal waste. Preferably, the cleaned wash water is stored in the second decantation tank. Due to the overflow, a higher purity for the cleaned wash water can be obtained since partial settling of fine particles can still occur in the first decantation tank. Furthermore, the second decantation tank serves as a buffer to accommodate fluctuations in volume of the cleaned wash water.

[0047] In an embodiment, the collected and fiber-free wash water flows into a third decantation tank after the first screen. The third decantation tank serves as a buffer for further cleaning steps of the collected wash water. Preferably, the collected and fiber-free wash water is pumped from the third decantation tank for separating the particles with a higher density than water, as in previously described embodiments.

[0048] In an embodiment, during the method, spilled wash water is collected on a water- impermeable surface, collected in a buffer and added to the third decantation tank. Preferably, the spilled water is collected in a gutter in the water-impermeable surface. This embodiment is advantageous because losses of process water, including wash water, are thereby limited for the highest possible efficiency for reusing water as, among others, wash water for washing the plastic and / or metal waste.

[0049] In an embodiment, the method additionally comprises the step of settling sludge after the step of screening. The settling of the sludge comprises the steps of:

[0050] - flowing the screened wash water over lamellae in a lamella separator,

[0051] - retention of the fine particles by the lamellae,

[0052] - settling the fine particles along the lamellae to form sludge,

[0053] - decanting the screened wash water over the lamellae, wherein water is separated from the screened wash water and the sludge, and

[0054] - flowing the decanted water to a water tank. The screened water preferably originates from the first and / or the second decantation tank.

[0055] Preferably, a flocculant is added to the screened wash water, wherein fine particles agglomerate. This is advantageous for the settling of the fine particles. Preferably, the flocculant is mixed with the screened wash water in a mixing tank by means of stirring elements. The screened wash water preferably has a minimum residence time of 1 hour in the mixing tank, more preferably 2 hours, even more preferably 3 hours and still more preferably 4 hours. The stirring elements preferably rotate at a maximum speed of 200 revolutions per minute, more preferably 100 revolutions per minute, even more preferably 75 revolutions per minute and still more preferably 50 revolutions per minute. This is advantageous because as a result formed flocs are not broken up again by the stirring elements.

[0056] The settling of the sludge from the screened wash water allows to obtain a higher degree of purity of the collected wash water. As a result, the water from the water tank can be used for cleaning, such as rinsing for example a filter or a screen, such as a belt press filter, or for cleaning the washing installation. In addition, it reduces wear and obstructions on pumps and pipes by removing abrasive particles. Furthermore, the settling of the sludge improves clarity and quality of the screened wash water, which is essential for an efficient cleaning of the plastic and / or metal waste. The water from the water tank can be added again to the first and / or second decantation tank, so that if there is still insufficient water present in the decantation tanks this can be replenished, or if a higher purity is required for washing the plastic and / or metal waste, the purity of the screened water in the first and / or second decantation tank can be increased.

[0057] In an embodiment, only a part of the screened wash water from the first decantation tank and / or the second decantation tank is pumped to the lamella separator to settle the sludge. This is advantageous to obtain different degrees of purity or contamination of the wash water in different steps of washing the plastic and / or metal waste. These different degrees of the wash water further allow to respond flexibly and quickly to varying load due to varying contamination of the wash water. A remaining part of the screened water from the first decantation tank and / or the second decantation tank is pumped to a washing installation for washing the plastic and / or metal waste. In a further embodiment, the step of settling sludge comprises the additional steps of: adding the sludge from the lamella separator to a buffer tank, and keeping the sludge from the lamella separator in suspension, preferably by means of moving mixing elements in the buffer tank. Keeping the sludge in suspension in the buffer tank serves as a buffer for further processing and separating the sludge from screened wash water. By keeping the sludge in suspension, premature maintenance on the buffer tank is avoided.

[0058] In an embodiment, the settling of the sludge in the lamella separator comprises the additional step of scraping off and removing foam present on a free water surface of the lamella separator. This prevents overflow of the foam to the water tank. As a result, contamination of the water by the foam is avoided. The foam from on the water surface is preferably added to the buffer tank.

[0059] In an embodiment, the method comprises the additional step of pressing a filter cake out of the sludge. Alternatively, a decanter centrifuge is used to dewater the sludge. Flottweg is a non-limiting example of a manufacturer of suitable decanter centrifuges. Screened wash water remaining in the sludge is separated from the filter cake. Said sludge originates from the lamella separator and / or the buffer tank. The remaining screened wash water flows to the first decantation tank. This is advantageous for a highest possible efficiency in being able to reuse wash water during the washing of the plastic and / or metal waste.

[0060] In a further embodiment, a dewatering additive is added to the sludge before the pressing and if applicable after keeping the sludge in suspension in the buffer tank. As a result, the sludge is further agglomerated so that the remaining wash water can be removed more simply from the sludge. Preferably, the sludge with dewatering additive is added to a mixing tank where the sludge and the dewatering additive are mixed. From the mixing tank, the sludge with dewatering additive goes to the pressing.

[0061] In an embodiment, the sludge is pressed between at least two belts. The at least two belts are moved between and over a series of rollers. As a result, the remaining screened wash water is pressed out of the sludge. Preferably, at the end of the series of rollers, the filter cake is scraped from the belts. Preferably, the belts are rinsed with water from the water tank as preparation to press new sludge. Because new sludge can be supplied continuously, filter cake is continuously removed from the at least two belts and the remaining screened wash water can flow away to the first decantation tank, the remaining screened wash water is pressed out of the sludge in an efficient manner.

[0062] In a preferred embodiment, at least the combination of washing the plastic and / or metal waste, collecting the wash water, screening with removal of the fibers from the collected wash water and collecting the screened wash water and decanting the cleaned wash water from the first decantation tank is combined with separating the particles with a density greater than water from the fiber-free wash water into the fiber-free and particle-free wash water, settling the sludge from the fiber-free and particle-free wash water, decanting the water during the settling of the sludge, readding cleaned wash water to the washing installation and adding the water to the washing installation. The steps are preferably performed for the cleaned wash water in the order: washing the plastic and / or metal waste, collecting the wash water, screening with removal of the fibers from the collected wash water, separating the particles with a density greater than water from the fiber-free wash water into the fiber-free and particle-free wash water, collecting the screened wash water and decanting the cleaned wash water from the first decantation tank and re-adding cleaned wash water to the washing installation. Preferably, after collecting the screened wash water and decanting the cleaned wash water from the first decantation tank, simultaneously with the previous steps, the settling of the sludge from the fiber-free and particle-free wash water, the decanting of the water during the settling of the sludge and the adding of the water to the washing installation are also performed.

[0063] In an embodiment, the plastic and / or metal waste is washed in a washing drum. The washing drum comprises driven rollers, a shell, an injector, paddles and a spiral.

[0064] Washing the plastic and / or metal waste comprises the steps of:

[0065] - bringing together the wash water with the plastic and / or metal waste in an injector,

[0066] - introducing the wash water and the plastic and / or metal waste into a shell of a washing drum by means of the injector,

[0067] - rotating the shell on driven rotating rollers,

[0068] - carrying the plastic and / or metal waste and a part of the wash water upwards along the shell by a spiral which is fixedly attached to an inner wall of the shell, wherein the upward carrying is performed by, among others, paddles which are positioned between successive windings of the spiral, - falling down of the plastic and / or metal waste and a part of the wash water downwards into the remaining part of the wash water,

[0069] - repeating the upward carrying and the falling down of the plastic and / or metal waste and a part of the wash water throughout the moving of the plastic and / or metal waste in the shell,

[0070] - removing the wash water and contamination through openings comprised in the shell, and

[0071] - removing the plastic and / or metal waste from the washing drum.

[0072] Preferably, the wash water is cleaned wash water as in previously described embodiments.

[0073] In an embodiment, washing the plastic and / or metal waste comprises the additional step of spraying off the plastic and / or metal waste by means of a spray nozzle. The plastic and / or metal waste is preferably sprayed off with cleaned wash water. Preferably, the step of spraying off is repeated during the moving of plastic and / or metal waste through the shell. Preferably, the plastic and / or metal waste is sprayed off at most three times in the shell. This is advantageous to remove adhering contamination from the plastic and / or metal waste. Furthermore, water can hereby be added to the wash water so that the contamination is diluted. As a result, further cleaning and transport of the wash water is simplified.

[0074] In an embodiment, washing the plastic and / or metal waste comprises the additional step of filtering wash water through a filter comprised in openings of the shell. Preferably, the step of filtering is repeated during moving of plastic and / or metal waste through the shell. More preferably, filtering is performed at most seven times in one shell, more preferably at most five times, more preferably at most three times. As a result, the plastic and / or metal waste can be easily separated from the wash water.

[0075] In a further embodiment, washing the plastic and / or metal waste comprises the additional step of cleaning the filter under pressure with water on an outer side of the shell. Preferably, the water is collected together with the wash water. As a result, pores of the filter remain free for continuous operation of the filter. Furthermore, as much water as possible is reused as wash water. In a second aspect, the invention relates to an apparatus for cleaning water originating from a processing process of plastic and / or metal waste.

[0076] Preferably, the processing process is a sorting process.

[0077] The apparatus comprises:

[0078] - a washing installation for washing the plastic and / or metal waste with wash water,

[0079] - a collection tank for collecting the wash water originating from the washing installation, and

[0080] - a cleaning installation for cleaning the collected wash water.

[0081] In an embodiment, the cleaning installation comprises one or more screens for screening the collected wash water for removing contamination from the collected wash water.

[0082] The cleaning installation comprises a first decantation tank for collecting and storing screened wash water. The first decantation tank comprises a decanting opening for decanting the screened wash water from the first decantation tank to obtain cleaned wash water.

[0083] The cleaning installation comprises a return line for returning cleaned wash water to the washing installation.

[0084] The apparatus for cleaning and reusing wash water from the washing installation for washing plastic and / or metal waste which is contaminated prior to a sorting process offers an improved circularity of the wash water. This helps to reduce the environmental impact and consumption of water as a raw material. It also results in a reduced load of any further biological or physicochemical water treatment and a lower economic cost. Preferably, the apparatus serves for plastic and / or metal waste originating from ASR, WEEE or incinerator bottom ash, wherein a large variety of contamination can be present in the wash water. The large variety and strongly fluctuating degree of contamination can be easily accommodated by the first decantation tank and collection tank as described for the apparatus.

[0085] In an embodiment, the cleaning installation comprises a first screen for removing fibers and solid particles from the collected wash water. The first screen is a drum screen. The first screen comprises an inlet for introducing the collected wash water onto the first screen. The first screen comprises a screen surface with pores for retaining the fibers and the solid particles from the collected wash water. The first screen comprises a first discharge and a second discharge respectively for removing the fibers and the solid particles from the first screen and for removing screened wash water from the first screen.

[0086] In an embodiment, the first screen comprises spirals for removing the fibers and the solid particles against the filter. As a result, the fibers and the solid particles can be scraped off and transported to the second discharge. Preferably, the first screen also comprises spray nozzles for clearing the screen surface on an outer side of the drum screen. The apparatus preferably comprises a pump for spraying water under high pressure through the spray nozzles.

[0087] In an embodiment, the pores have a cross-section of 50-1000 pm. Preferably, the pores have a cross-section of 100-800 pm, more preferably of 150-600 pm. As a result, the fibers, but also additionally coarser solid particles, can be retained from the collected wash water.

[0088] In an embodiment, the drum screen has a length between 1 m and 4 m. Preferably, the length is at least 1 m, more preferably at least 1.3 m, more preferably at least 1.8 m. Preferably, the length is at most 4 m, more preferably at most 3.5 m, more preferably at most 3 m. As a result, there is sufficient length for the collected wash water to flow through the filter and to retain the fibers and solid particles. Furthermore, the length is sufficiently long to carry the fibers and the solid particles along via tangential filtration.

[0089] In an embodiment, the cleaning installation comprises a hydrocyclone for separating particles with a higher density than water from the collected wash water. Preferably, the collected wash water is also fiber-free and originating from the first screen. The particles with a higher density than water are for example sand or other sediments. The hydrocyclone comprises a supply for introducing the collected wash water into the hydrocyclone. The hydrocyclone comprises a first discharge and a second discharge respectively for removing particle-free wash water to the first decantation tank and for removing said particles with remaining wash water from the hydrocyclone. By means of the hydrocyclone, large flow rates can be processed efficiently at a high speed. Furthermore, the maintenance of hydrocyclones is generally simple, because the hydrocyclone has no moving parts. Moreover, hydrocyclones can handle a large variety of flow rates. As a result, the hydrocyclone can handle a large difference in contamination with particles in the collected wash water.

[0090] In an embodiment, the hydrocyclone has a ratio of a diameter of the supply relative to a diameter of the hydrocyclone between 0.1 and 0.7, preferably between 0.2 and 0.6, more preferably between 0.3 and 0.5. This is advantageous in order to generate a sufficiently large velocity difference between particles having different densities, thereby increasing the separation efficiency without causing excessive pressure drops.

[0091] In an embodiment, the hydrocyclone has a ratio of a diameter of the second discharge relative to a diameter of the hydrocyclone between 0.15 and 0.45, preferably between 0.20 and 0.40, more preferably between 0.25 and 0.35. This is advantageous because an improved separation of fine particles can be obtained without causing too high pressure losses.

[0092] In an embodiment, the cleaning installation comprises a second screen for removing the remaining wash water from the particles. The second screen is a vibrating screen. The second screen comprises a supply for introducing the particles with the remaining wash water onto a screen surface of the second screen. The second screen comprises a first discharge and a second discharge respectively for removing the remaining wash water separated from the particles and for removing the particles from the screen surface.

[0093] The second screen reduces abrasion by the sand during the washing whereby the washing installation exhibits less wear whereby less maintenance is also necessary. Furthermore, removing the sand prevents wear on pumps or other components within the apparatus. Furthermore, the sand will not be reintroduced into the washing installation, whereby concentration increase of the sand will not occur.

[0094] In an embodiment, the vibrating screen is vibratable in a linear, circular or elliptical motion. Preferably, the vibrating screen is vibratable in an elliptical motion. As a result, the particles with the remaining wash water can be processed in their sticky or wet form. In an embodiment, the cleaning installation comprises a third screen for separating remaining wash water from the plastic and / or metal waste. The remaining wash water is carried along by the plastic and / or metal waste from the washing installation. The remaining wash water flows through a screen surface of the third screen. The plastic and / or metal waste is transportable over the screen surface of the third screen. Preferably, the third screen is a vibrating screen. More preferably, the vibrating screen comprises two compartments for stepwise removing the remaining wash water. The third screen allows maximum recovery of the wash water. The remaining wash water can be combined with the collected wash water.

[0095] In a preferred embodiment, the cleaning installation comprises a second decantation tank for the overflowing of screened wash water from the first decantation tank to the second decantation tank. The cleaned wash water is reusable from the second decantation tank for washing the contaminated plastic and / or metal waste. This means that the return line in this embodiment runs from the second decantation tank back to the washing installation. Preferably, the cleaned wash water is stored in the second decantation tank. Due to the overflowing of the screened wash water into the second decantation tank, a higher purity of the cleaned wash water can be obtained, because partial settling of fine particles can still occur in the first decantation tank. Furthermore, the second decantation tank can serve as a buffer to accommodate fluctuations in volume of the cleaned wash water. The fine particles do not belong to the particles separated by the second screen.

[0096] In an embodiment, the cleaning installation comprises a third decantation tank for storing the collected and fiber-free wash water. The third decantation tank thus comes after the first screen. The third decantation tank can serve as a buffer for further cleaning steps of the collected and fiber-free wash water. From the third decantation tank, the collected and fiber-free wash water can be pumped to the hydrocyclone for separating the particles from the collected and fiber-free wash water.

[0097] In an embodiment, the apparatus is placed on a water-impermeable surface. The apparatus comprises a gutter for collecting water on the water-impermeable surface. Optionally, losses of the processing process of the plastic and / or metal waste can be collected in the gutter, collected in a buffer and added to the third decantation tank. As a result, losses during the cleaning of the wash water can be avoided maximally to achieve the highest possible efficiency.

[0098] In an embodiment, the cleaning installation comprises one or more settling tanks. At least one settling tank is a lamella separator. The cleaning installation comprises a water tank for storing water from the lamella separator. The lamella separator comprises a supply for introducing the screened wash water into the settling tank. The lamella separator comprises lamellae for retaining and settling fine particles into sludge from the screened wash water. Preferably, the fine particles are agglomerated. The lamella separator comprises a first discharge and a second discharge respectively for removing the sludge along the lamellae and for decanting water over the lamellae to the water tank.

[0099] In an embodiment, the lamellae are positioned at an angle of at least 45° and at most 75° relative to a horizontal plane. Preferably, the lamellae are positioned at an angle of at least 50° relative to a horizontal plane, more preferably at least 55°, more preferably at least 57°. Preferably, the lamellae are positioned at an angle of at most 70° relative to a horizontal plane, more preferably at most 65°, more preferably at most 63°. As a result, the fine particles or the agglomerated fine particles can be retained in the flow of the screened wash water and settle by sliding down.

[0100] In a further embodiment, the cleaning installation comprises a buffer tank for storing and buffering the sludge. The buffer tank comprises a first inlet for introducing the sludge. The buffer tank comprises one or more rotatable mixing elements for keeping the sludge in suspension. The buffer tank comprises a discharge for removing the sludge in suspension from the buffer tank. The buffer tank can serve as a buffer for further processing and separating the sludge from screened wash water. Furthermore, the buffer tank can keep the sludge in suspension so that no accumulation of sludge can occur on a bottom of the buffer tank, whereby maintenance needs to be performed less frequently. Furthermore, accumulation of sludge on the bottom can reduce the volume for storing sludge and reduce the buffer.

[0101] In an embodiment, the buffer tank comprises at most ten rotatable mixing elements, preferably at most six, more preferably at most three. The plurality of rotatable mixing elements can keep the sludge in homogeneous suspension over a full depth of the buffer tank. In an embodiment, the lamella separator comprises a scraper for removing foam at a free water surface of the lamella separator. Preferably, the cleaning installation comprises a transport means for transferring the scraped foam to the buffer tank from a previously described embodiment. The scraper can remove the foam from the water surface, so that contamination of the water by the foam in the water tank can be avoided.

[0102] In an embodiment, the cleaning installation comprises a press for separating wash water from the sludge. The press is a belt filter press or a chamber filter press. The press comprises an inlet for introducing the sludge, wherein the press comprises a filter for retaining filter cake from the sludge and separating the wash water, wherein the press comprises a first discharge and a second discharge respectively for removing the filter cake of the filter from the press and for removing wash water from the sludge from the press to the first decantation tank. This is advantageous for a highest possible efficiency in being able to reuse wash water during the washing of the contaminated plastic and / or metal waste.

[0103] In an alternative embodiment, the cleaning installation comprises a decanter centrifuge for separating wash water from the sludge. Flottweg is a non-limiting example of a manufacturer of suitable decanter centrifuges. A decanter centrifuge has similar advantages as a press. The decanter centrifuge comprises an inlet for introducing the sludge, a first discharge for removing the filter cake from the decanter centrifuge and a second discharge for removing wash water from the sludge from the decanter centrifuge to the first decantation tank.

[0104] In an embodiment, the cleaning installation comprises one or more addition stations. A first possible addition station is for adding flocculant to the screened wash water. A second possible addition station is for adding anti-foaming agent to the collected wash water. A third possible addition station is for adding dewatering additive to the sludge in suspension. As a result, the fine particles can be agglomerated. Additionally, foam formation can be avoided in the cleaning installation. As a result, the sludge can be further agglomerated and dewatered so that the remaining wash water can be removed more simply from the sludge. Preferably, the presence of one or more addition stations in the apparatus is determined according to a ranking as listed above. In an embodiment, the press comprises at least two belts and a series of rollers. The at least two belts lie in loops around the rollers. The at least two belts lie in pairs opposite each other and form a passage for the sludge. In operation, the sludge is moved through the passage and pressed between two opposite belts. Preferably, the press comprises not more than at most three pairs of belts which are placed one after another. The belts and the series of rollers can continuously and efficiently press the wash water out of the sludge.

[0105] In an embodiment, the series of rollers comprises at least three rollers. Preferably, the press comprises not more than at most ten rollers which are positioned successively and next to each other separated only by the belts. More preferably, the series of rollers comprises at least five and at most eight rollers. The belts and the series of rollers can continuously and efficiently press the wash water out of the sludge.

[0106] In an embodiment, the press comprises a scraper for scraping the filter cake from the belts at the end of the series of rollers. The scraper can remove the filter cake from the at least two belts in a continuous manner.

[0107] In an embodiment, the press comprises spray nozzles for rinsing the belts with water. Preferably, the water originates from the water tank as preparation to be able to press new sludge between the belts. The spray nozzles can remove the filter cake from the at least two belts in a continuous manner, so that the at least two belts no longer comprise sludge. Preferably, there is at least one spray nozzle for rinsing each belt of the at least two belts.

[0108] In a preferred embodiment, the apparatus comprises at least the washing installation, the drum filter screen, the hydrocyclone, the first decantation tank, the lamella separator and the water tank. Preferably, the wash water can return from the washing installation to the washing installation with passing through the drum filter screen, the hydrocyclone and the first decantation tank in that order. Preferably, the water additionally passes through the lamella separator and the water tank after the first decantation tank. Preferably, the apparatus additionally comprises a second decantation tank and a third decantation tank. More preferably, the installation also comprises a second, a third screen and a buffer tank. Even more preferably, the apparatus comprises the plurality of addition stations. In an embodiment, the washing installation is a washing drum. The washing drum comprises an injector for introducing the cleaned wash water and the contaminated plastic and / or metal waste. The washing drum comprises a shell. The washing drum comprises a spiral for moving the wash water through the shell. The spiral comprises paddles for upward carrying the contaminated plastic and / or metal waste and a part of the wash water. The paddles are transverse connections between successive windings of the spiral. The washing drum comprises a first discharge and a second discharge for removing the wash water from the washing drum and respectively for removing the plastic and / or metal waste from the washing drum. The shell is rotatable by rollers, wherein the rollers are drivable. The spiral is attached to an inner side of the shell. The spiral preferably extends over an entire length of the shell. The injector and the second discharge are each located at an opposite end of the shell according to a direction in which the shell extends. The shell comprises openings for removing wash water from the shell to the first discharge.

[0109] In an embodiment, the shell is divided into at least four zones between the inlet and the second discharge. A first zone is configured for soaking, lifting and letting down the contaminated plastic and / or metal waste in the wash water. The shell is closed in the first zone, so that the wash water cannot leave the washing drum. The contaminated plastic and / or metal waste is washed in the first zone. The first zone is a washing zone. A second zone follows the first zone. The second zone comprises openings in the shell. The second zone is configured for spraying off the contaminated plastic and / or metal waste and removing wash water from the plastic and / or metal waste along the openings. The second zone is a screening zone. The second zone preferably comprises one or more spray nozzles within the shell for spraying off the plastic and / or metal waste. The second zone is followed by a third zone. The shell is closed in the third zone, so that the wash water cannot leave the washing drum. The plastic and / or metal waste is rinsed in the third zone. The spiral is preferably higher at a beginning and an end of the third zone, so that the wash water cannot immediately leave the third zone. As a result, the plastic and / or metal waste can also soak for a while during the rinsing. The third zone is configured for rinsing, soaking, lifting and letting down the contaminated plastic and / or metal waste in the wash water. The third zone is followed by a fourth zone. The fourth zone comprises openings in the shell. The fourth zone is configured for removing wash water along the openings. Preferably, the fourth zone is configured for carrying along and letting down the plastic and / or metal waste. This is advantageous to remove as much wash water as possible from the plastic and / or metal waste. The fourth zone is free of spray nozzles within the shell, so that no additional wash water is added and as dry as possible plastic and / or metal waste is obtained from the fourth zone. The fourth zone is a last screening zone in the washing drum.

[0110] It is clear that the washing drum can comprise multiple rinsing zones and screening zones, which preferably alternate with each other between the washing zone and the last screening zone.

[0111] Preferably, the shell comprises paddles in the first zone, the third zone and the fourth zone for carrying the plastic and / or metal waste and a part of the water, so that the contaminated plastic and / or metal waste can be carried upwards with the paddles, to subsequently fall down. As a result, contamination can be removed from the plastic and / or metal waste or the wash water can be removed from the plastic and / or metal waste.

[0112] In an embodiment, there is a difference between an outer diameter and an inner diameter of the spiral between 50 mm and 700 mm, preferably between 150 mm and 600 mm, more preferably between 250 mm and 500 mm. A sufficient difference between the outer diameter and the inner diameter of the spiral allows a sufficient amount of the contaminated plastic and / or metal waste and the wash water to be carried along to be transported through the shell. As a result, a mass of at least 1.5 tons per hour of the contaminated plastic and / or metal waste can be washed.

[0113] In an embodiment, an outer diameter of the spiral is at most 5 m, preferably at most 4.5 m, more preferably at most 4.0 m, more preferably at most 3.5 m, more preferably at most 3.0 m, more preferably at most 2.5 m. The inner diameter of the spiral is at least 1.5 m, preferably at least 1.6 m, more preferably at least 1.7 m, even more preferably at least 1.8 m, still more preferably at least 1.9 m and most preferably at least 2.0 m. As a result, sufficient height is available to carry the contaminated plastic and / or metal waste and a part of the wash water without the washing drum taking on large dimensions. As a result, the curvature of the shell is sufficiently large to readily carry the contaminated plastic and / or metal waste and allow it to fall.

[0114] In an embodiment, the spiral has a pitch between 100 mm and 700 mm, preferably 150 mm to 650 mm, more preferably 200 mm to 600 mm, more preferably 250 mm to 550 mm, more preferably 300 mm to 500 mm. A sufficiently large pitch of the spiral is necessary to be able to sufficiently transport the contaminated plastic and / or metal waste in the shell, so that pieces of plastic and / or metal waste fit between two successive windings of the spiral. Preferably, the spiral has a constant pitch.

[0115] In an embodiment, the paddles are positioned between two successive windings of the spiral. The paddles are preferably radially oriented and preferably extend from the inner diameter to the outer diameter. Preferably, the paddles are flat. Preferably, the paddles are more numerous in the first zone than in the third zone and the fourth zone to allow the plastic and / or metal waste to be carried more frequently. This is advantageous because the contaminated plastic and / or metal waste contains more contamination at the beginning of the washing drum than toward the end of the washing drum, and therefore requires less intensive washing.

[0116] In an embodiment, the shell has a length between 2 m and 12 m. Preferably, the length is at least 3 m, more preferably at least 4 m, more preferably at least 5 m. Preferably, the length is at most 11 m, more preferably at most 10 m, more preferably at most 9 m. As a result, there is sufficient length to wash the contaminated plastic and / or metal waste. Furthermore, the length is sufficiently long to implement the four different zones therein with sufficient length for each zone to be able to perform its intended operation.

[0117] In an embodiment, the washing drum comprises one or more spray nozzles for spraying off the plastic and / or metal waste in the washing drum. Preferably, a part of the spray nozzles is placed within the shell in the second zone for spraying off the contaminated plastic and / or metal waste. Preferably, at most three spray nozzles are placed in the shell. This is advantageous to be able to remove adhering contamination from the plastic and / or metal waste. Furthermore, water can hereby be added to the wash water so that the contamination is diluted. As a result, further cleaning and transport of the wash water is simplified.

[0118] In an embodiment, the washing drum comprises a filter in the openings in the shell for filtering wash water. As a result, the plastic and / or metal waste can be easily separated from the wash water. Furthermore, in combination with the step of spraying off, water can be added to reduce concentration of the contamination in the wash water and to be able to guarantee continuous removal of the wash water. As a result, a good cleaning of the plastic and / or metal waste can be obtained. In an embodiment, the filter is a wedge wire filter. Preferably, there is a spacing between the various wedge wires of 0.75 mm to 1.25 mm, more preferably of 0.85 mm to 1.20 mm, more preferably of 0.95 mm to 1.15 mm, more preferably of 1.00 mm to 1.10 mm. The spacing is measured at a narrowest point between adjacent wires. By means of the wedge wire filters, wash water containing contamination can be efficiently removed from the washing drum, whereby the particles and fibers are entrained. Hereby, the contaminated plastic and / or metal waste can be sufficiently retained for a highest possible yield of sorted plastic and / or metal waste.

[0119] In an embodiment, a part of the spray nozzles is placed on an outer side of the shell for cleaning the filters with water under high pressure. Preferably, each zone with a filter comprises spray nozzles on the outer side of the shell. As a result, pores of the filter remain free for continuous operation of the filter. Preferably, the second discharge is configured for discharging both the wash water and the water for rinsing the filters. Thus, as much water as possible is reused as wash water.

[0120] One skilled in the art will appreciate that a method according to the first aspect is preferably performed by means of an apparatus according to the second aspect and that an apparatus according to the second aspect is preferably configured for performance of a method according to the first aspect. Each feature described in this document, above as well as below, can consequently relate to each of the three aspects of the present invention.

[0121] In a third aspect, the invention relates to a use of a method according to the first aspect and / or an apparatus according to the second aspect for cleaning and reusing water originating from a processing process of plastic and / or metal waste, wherein the waste originates from automotive shredder residue, from waste electrical and electronic equipment or from incinerator bottom ash.

[0122] The processing process is preferably a sorting process. This use results in an advantageous separation of contamination in the wash water for waste streams originating from ASR, WEEE or incinerator bottom ash.

[0123] The entire invention leads to a reduced use of detergents because foam can be removed efficiently without additional anti-foaming agents or with a strongly reduced concentration thereof. In addition, the efficiency and effectiveness of the washing of mixed waste is significantly improved. The apparatus with 4 sequential zones in one rotating drum combines soaking, draining, rinsing and repeated draining in one setup, resulting in multiple waste streams with progressive separation of inerts and organics without press water recycling or sediment problems. The specific design with paddles, funnels and openings ensures controlled discharge and flow, which enables a coordinated interaction that is not evident in single- or two-phase systems. This is particularly more advantageous compared to traditional systems, due to reduced mechanical wear, no need for extra fresh water (zero wastewater), lower energy requirement due to reduced viscosity at high temperature, and complete hygienization without biological pre-treatment. The drum saves space, reduces transport between phases and prevents accumulation of fine minerals, salts or heavy metals, which leads to higher biogas yield and recyclable fraction.

[0124] EXAMPLES

[0125] The invention will now be further elucidated on the basis of the following examples, without otherwise being limited thereto. The examples describe an apparatus and a method for cleaning wash water originating from a processing process of plastic and / or metal waste, whereby water recovery within the processing process is possible.

[0126] EXAMPLE 1

[0127] Example 1 relates to an embodiment of a method and an apparatus for washing plastic and / or metal waste with water recovery. The method in example 1 is schematically shown in Figure 1.

[0128] Figure 1 shows a flow diagram of a method according to an embodiment of the present invention.

[0129] 101) contaminated plastic and / or metal waste

[0130] 102) washed plastic and / or metal waste

[0131] 103) collected wash water

[0132] 104) contamination

[0133] 105) screened wash water

[0134] 106) cleaned wash water

[0135] 201) washing the contaminated plastic and / or metal waste in the washing installation 202) collecting wash water in the collection tank

[0136] 203) screening the collected wash water in the first screen

[0137] 204) storing screened wash water in a first decantation tank

[0138] 205) decanting cleaned wash water from the first decantation tank

[0139] The apparatus comprises a washing installation, a cleaning installation, a collection tank and a return line. The plastic and / or metal waste is introduced into the washing installation together with cleaned wash water. The plastic and / or metal waste is washed with wash water, whereby contamination is removed from the plastic and / or metal waste to obtain washed plastic and / or metal waste. The wash water from the washing installation is collected in the collection tank. From the collection tank, the collected wash water is brought to the cleaning installation. The cleaning installation comprises a first screen. The first screen is a drum screen. The collected wash water is introduced into the first screen by means of a supply. The collected wash water passes through a screen surface of the first screen, whereby screened wash water is obtained. The contamination, being fibers and solid particles, is removed from the collected wash water to form fiber-free wash water. The fibers and the solid particles are removed from the first screen by means of spirals. The screened wash water is subsequently stored in a first decantation tank via a supply. The screened water is decanted from the first decantation tank via a discharge. The cleaned wash water is reused in the washing installation by means of the return line. In the first decantation tank, sand and fine particles possibly settle.

[0140] The washing installation is a washing drum. The washing drum comprises an injector for introducing the cleaned wash water and the plastic and / or metal waste. The washing drum comprises a shell. The washing drum comprises a spiral for moving the wash water and the plastic and / or metal waste through the shell. The spiral comprises paddles for upward carrying the plastic and / or metal waste and a part of the wash water. The paddles are transverse connections between successive windings of the spiral. The washing drum comprises a first discharge and a second discharge respectively for removing the wash water together with contamination and for removing the washed plastic and / or metal waste from the washing drum. The shell is rotated by driven rollers. The spiral is attached to an inner side of the shell. The injector and the second discharge are located at opposite ends of the shell in a direction in which the shell extends. The shell comprises openings for removing wash water together with contamination from the washing drum to the first discharge. The shell is divided into four zones between the inlet and the second discharge. A first zone is for washing, soaking, lifting the plastic and / or metal waste out of and dropping it into the wash water. A second zone is for spraying off the plastic and / or metal waste and for removing the wash water along the openings which comprise filters. A third zone is for rinsing the plastic and / or metal waste. A fourth zone for draining the wash water from the plastic and / or metal waste. The shell comprises paddles in the first zone, the third zone and the fourth zone for carrying the plastic and / or metal waste and a part of the water. The windings of the spiral comprise an inner side and an outer side.

[0141] EXAMPLE 2

[0142] This example relates to another embodiment of a method and an apparatus for washing plastic and / or metal waste with water recovery.

[0143] Figure 2 shows a flow diagram of a method according to another embodiment of the present invention.

[0144] 101) contaminated plastic and / or metal waste

[0145] 102) washed plastic and / or metal waste

[0146] 103) collected wash water

[0147] 106) cleaned wash water

[0148] 107) fibers

[0149] 108) particles with remaining wash water

[0150] 109) particles

[0151] 110) remaining wash water

[0152] 111) fiber-free and particle-free wash water

[0153] 112) flocculant

[0154] 113) water free of sludge

[0155] 114) sludge

[0156] 201) washing the contaminated plastic and / or metal waste in the washing installation

[0157] 202) collecting wash water in the collection tank

[0158] 205) decanting cleaned wash water from the first decantation tank

[0159] 206) screening the collected wash water into fiber-free wash water

[0160] 207) separating particles with remaining wash water and particle-free wash water from the fiber-free wash water in a hydrocyclone

[0161] 208) screening particles with remaining wash water on the second screen 209) storing the fiber-free and the particle-free wash water in a first decantation tank

[0162] 210) settling the sludge from the fiber-free and the particle-free wash water with flocculant in a lamella separator and separating water to a water tank in step 211)

[0163] 211) decanting water from the water tank

[0164] The apparatus comprises a washing installation, a cleaning installation, a collection tank and a return line. The cleaning installation comprises a first screen, a hydrocyclone, a second screen, a first decantation tank, a settling tank and a water tank. The plastic and / or metal waste is introduced into a washing installation together with cleaned wash water. The plastic and / or metal waste is washed whereby contamination is removed from the plastic and / or metal waste. The wash water from the washing installation is collected in a collection tank. From the collection tank, the collected wash water is brought to the cleaning installation. The first screen is a drum screen and comprises a supply, a first discharge and a second discharge for respectively introducing the collected wash water, removing fiber-free wash water and removing fibers and solid particles from the first screen. Subsequently, fiber-free wash water is pumped to the hydrocyclone. Particles with a density greater than water, such as sand, are separated from the wash water in the hydrocyclone. The fiber- and particle-free wash water leaves the hydrocyclone by means of the first discharge and the particles leave the hydrocyclone by means of the second discharge. The particle-free wash water flows from the hydrocyclone to the first decantation tank, where it is temporarily stored. Subsequently, the particles with remaining wash water are brought onto the second screen by means of a supply of the second screen. The second screen is a vibrating screen, which separates the remaining wash water from the particles, and by means of a first discharge of the second screen the remaining wash water flows to the first decantation tank. A part of the fiber-free and the particle-free wash water from the first decantation tank is decanted along a first discharge of the first decantation tank and is reused as cleaned wash water along the return line. Another part of the fiber-free and the particle-free wash water from the first decantation tank is brought to the settling tank by means of a second discharge. The settling tank is a lamella separator. A flocculant is added to the other part of the fiber-free and the particle-free wash water for agglomerating fine particles. The flocculant is added in a mixing tank and mixed with the fiber-free and particle-free wash water with stirring elements. In the lamella separator, the fine particles are settled along lamellae to form sludge. The lamellae are at an angle of 50° with respect to a horizontal plane. The fiber-free and particle-free wash water decants over the lamellae until water free of sludge is obtained. The water is temporarily stored in the water tank before it is reused in the washing installation, wherein the water sprays the plastic and / or metal waste free of contamination, and optionally cleans filters of the washing installation. Filters of the washing installation are wedge wire filters with a spacing between the various wedge wires of 0.15 mm to 1.25 mm. The sludge is removed from the lamella separator. The use of these lamellae ensures an increased separation efficiency compared to one- or two-phase systems. This in particular for this example ensures a 1.1 more efficient to 4 times more efficient separation.

[0165] EXAMPLE 3

[0166] Example 3 relates to a further embodiment of example 2. The cleaning installation additionally comprises a third decantation tank, a second decantation tank, a buffer tank and a press.

[0167] Figure 3 shows a flow chart of a method according to a further embodiment of the present invention.

[0168] 101) contaminated plastic and / or metal waste

[0169] 102) washed plastic and / or metal waste

[0170] 103) collected wash water

[0171] 106) cleaned wash water

[0172] 107) fibers

[0173] 108) particles with remaining wash water

[0174] 109) particles

[0175] 110) remaining wash water

[0176] 111) fiber-free and particle-free wash water

[0177] 112) flocculant

[0178] 113) water

[0179] 114) sludge

[0180] 115) dewatering additive

[0181] 116) filter cake

[0182] 117) remaining water in the sludge

[0183] 201) washing the contaminated plastic and / or metal waste in the washing installation

[0184] 202) collecting wash water in the collection tank

[0185] 205) decanting cleaned wash water from the first decantation tank

[0186] 206) screening the collected wash water into fiber-free wash water 207) separating particles with remaining wash water and particle-free wash water from the fiber-free wash water in a hydrocyclone

[0187] 208) screening particles with remaining wash water on the second screen

[0188] 209) storing the fiber-free and the particle-free wash water in a first decantation tank

[0189] 210) settling the sludge from the fiber-free and the particle-free wash water with flocculant in a lamella separator and separating water to a water tank

[0190] 211) decanting water from the water tank

[0191] 212) buffering the fiber-free wash water in the third decantation tank

[0192] 213) decanting the fiber-free and the particle-free wash water from the second decantation tank to a lamella separator

[0193] 214) keeping the sludge in suspension in a buffer tank.

[0194] 215) pressing the sludge to separate the remaining wash water and the filter cake from the sludge

[0195] 216) buffering the fiber-free and the particle-free wash water in the second decantation tank

[0196] After the first screen, the fiber-free wash water is temporarily stored in the third decantation tank as a buffer for other parts of the cleaning installation. From the third decantation tank, the fiber-free wash water is pumped to the hydrocyclone. After the first decantation tank, the fiber-free and particle-free wash water is decanted into a second decantation tank and from the second decantation tank the cleaned wash water is fed along a first discharge of the second decantation tank and along the return line to the washing installation for reusing the cleaned wash water in the washing installation. Optionally, a gutter is comprised in the installation for collecting water on a non-water-permeable surface on which the installation stands. Optionally, losses from the sorting process of the plastic and / or metal waste can be caught in the gutter, collected in a buffer and added to the first decantation tank. The sludge originating from the lamella separator flows by means of a second discharge of the lamella separator to a supply of the buffer tank. Due to the use of the lamella separator, 5-80% less foam is present. As a result, the amount of detergents can be limited to 0 volume % or 95 volume %. In the buffer tank, the sludge is kept in suspension by rotating mixing elements, preferably two rotating mixing elements. Subsequently, dewatering additive is added to the sludge in suspension and pumped to the press. The press is a belt filter press, but can also be a chamber filter press or decanter centrifuge. In the press, remaining water is separated from the sludge in suspension, and flows back into the first decantation tank. EXAMPLE 4

[0197] Example 4 relates to a washing drum as washing installation of the apparatus, as shown in Figure 4A and Figure 4B.

[0198] Figure 4A shows a perspective view of a washing drum according to an embodiment of the present invention.

[0199] Figure 4B shows a detailed representation of a spiral comprised in the washing drum from Figure 2A.

[0200] The washing drum (1) comprises an injector for introducing the cleaned wash water and the plastic and / or metal waste. The injector feeds the cleaned wash water and waste to a first end (15) of a shell of the washing drum (1). The washing drum (1) comprises a spiral (3) for moving wash water and waste through the shell. The spiral (3) comprises paddles (2) for upward carrying the plastic and / or metal waste and a part of the wash water. The paddles (2) are transverse connections between successive windings (4) of the spiral (3). The washing drum (1) comprises a first discharge (16) and a second discharge (7) respectively for removing the wash water from the washing drum (1) and for removing the plastic and / or metal waste from the washing drum (1). The shell is rotated by driven rollers (12). The spiral (3) is attached to an inner side of the shell. The injector and the second discharge (7) are each located at opposite ends of the shell in a direction in which the shell extends. The shell comprises openings for removing the wash water from the shell to the first discharge (16). The shell is divided into four zones between the inlet and the second discharge (7). A first zone (5) is for soaking, carrying and letting down the plastic and / or metal waste in the wash water. A second zone (6) is for removing the wash water along the openings. A third zone (8) is for rinsing and for carrying and letting down the plastic and / or metal waste in the wash water. A fourth zone (9) is for removing the wash water along the openings. The washing drum (1) comprises at the second discharge (7) a funnel (10) for collecting the plastic and / or metal waste from the shell. The shell comprises paddles (2) in the first zone (5), the third zone (8) and the fourth zone (9) for carrying the plastic and / or metal waste and a part of water. The windings (4) of the spiral (3) have an inner diameter and an outer diameter. Between the outer diameter and the inner diameter is a difference between 250 mm and 450 mm. An outer diameter of the spiral (3) is from 1.6 m to 3.2 m. The pitch of the spiral (3) is from 325 mm to 375 mm and constant over a length over which the spiral (3) extends. The paddles (2) are plates positioned between two successive windings (4) of the spiral (3), are radially oriented and extend from the inner diameter to the outer diameter. The paddles (2) are more numerous in the first zone (5), with six paddles (2) per winding, than in the third zone (8) and the fourth zone (9), with four paddles (2) per winding (4), to allow the plastic and / or metal waste to be carried more frequently. The shell has a length between 5.5 m and 8.5 m. The washing drum comprises filters (11) in openings of the shell in the second zone (6), the third zone (7) and the fourth zone (9) for filtering the wash water of the contamination. The washing drum (1) comprises one spray nozzle for spraying off the plastic and / or metal waste in the second zone (6). The filter (11) is a wedge wire filter (11). The washing drum (1) comprises spray nozzles (14) on an outer side of the shell for cleaning all filters (11) with the water under pressure. Under the washing drum (1) is a platform (13).

Claims

CLAIMS1. Method for cleaning wash water prior to a sorting process of plastic and / or metal waste, comprising the steps of: washing the plastic and / or metal waste with wash water, collecting the wash water originating from the washing, and cleaning wash water originating from the collecting, wherein the wash water originating after cleaning is reused in the step of washing the plastic and / or metal waste, wherein cleaning the collected wash water comprises the step of screening, wherein during the screening contamination is separated from the collected wash water, wherein screened wash water is collected in a first decantation tank, wherein the screened wash water collected in the first decantation tank is decanted from the first decantation tank characterized in that the plastic and / or metal waste is washed in a washing drum, wherein the washing drum is divided into at least 4 zones, a first zone for soaking, carrying and letting down the plastic and / or metal waste in the wash water, a second zone for removing the wash water, a third zone for rinsing and for carrying and letting down the plastic and / or metal waste in the wash water and a fourth zone for removing the wash water along at least one opening.

2. The method according to claim 1, characterized in that the step of screening comprises a sub-step, wherein the collected wash water is screened by means of a first screen, wherein the first screen removes fibers and solid particles from the collected wash water, wherein wash water passes through pores of the first screen, wherein the fibers and the solid particles are retained by the first screen, wherein the fibers and the solid particles are separated from the first screen.

3. The method according to claim 1 or 2, characterized in that the step of screening comprises a sub-step, wherein particles with a higher density than water are separated from the collected wash water, wherein the wash water from which said particles have been separated is collected in the first decantation tank, wherein the separated particles are screened with a second screen for separating remaining wash water from the separated particles and wherein the remaining wash water is collected in the first decantation tank.

4. The method according to one of the preceding claims 1-3, characterized in that the method additionally comprises the step of settling sludge after the step ofscreening, wherein the settling comprises the steps of: adding a flocculant to the screened wash water wherein fine particles agglomerate, flowing the screened wash water over lamellae in a lamella separator, retaining the agglomerated fine particles by the lamellae, settling the agglomerated fine particles along the lamellae to form sludge, decanting the screened wash water over the lamellae wherein water is separated from the screened wash water and the sludge, and flowing the decanted water to a water tank.

5. The method according to claim 4, characterized in that the step of settling sludge comprises the additional steps of: adding the sludge from the lamella separator to a buffer tank, and keeping the sludge from the lamella separator in suspension by means of moving mixing elements in the buffer tank.

6. The method according to claim 4 or 5, characterized in that the settling of the sludge in the lamella separator comprises the additional step of scraping off and removing foam present on the water surface of the lamella separator.

7. The method according to one of the preceding claims 4-6, characterized in that the method comprises the additional step of pressing a filter cake out of the sludge, wherein screened wash water remaining in the sludge is separated from the filter cake, wherein the remaining screened wash water flows to the first decantation tank.

8. The method according to one of the preceding claims 1-7, characterized in that the plastic and / or metal waste is washed in a washing drum, wherein the washing drum comprises driven rollers, a shell, an injector, paddles and a spiral, wherein the cleaned wash water is brought together with the plastic and / or metal waste in the injector, wherein the cleaned wash water and the plastic and / or metal waste are introduced into the shell of the washing drum by means of the injector, wherein the shell is rotated on the driven rotating rollers, wherein the plastic and / or metal waste and a part of the wash water are carried along upwards along the shell by the spiral which is fixedly attached to an inner wall of the shell, wherein the upward carrying is performed by, among others, the paddles which are positioned between successive windings of the spiral, wherein the plastic and / or metal waste and a part of the wash water fall back down into the remaining part of the wash water, wherein a cycle of the upward carrying and the falling down of the plastic and / or metal waste and a part of the wash water repeats itselfthroughout the moving of the plastic and / or metal waste through the washing drum, wherein the wash water and contamination are removed from the washing drum through a filter comprised in parts of the shell and wherein the plastic and / or metal waste is removed from the washing drum.

9. Apparatus for cleaning water originating from a sorting process of plastic and / or metal waste comprising: a washing installation for washing the plastic and / or metal waste with wash water, a collection tank for collecting the wash water originating from the washing installation, and a cleaning installation for cleaning collected wash water, wherein the cleaning installation comprises one or more screens for screening the collected wash water for removing contamination from the collected wash water, wherein the cleaning installation comprises a first decantation tank for collecting and storing screened wash water, wherein the first decantation tank comprises a decanting opening for decanting the screened wash water from the first decantation tank to obtain cleaned wash water, wherein the cleaning installation comprises a return line for returning cleaned wash water to the washing installation characterized in that the washing installation is a washing drum, wherein the washing drum comprises a shell, wherein the washing drum comprises a spiral for moving the wash water through the shell, wherein the spiral comprises paddles for upward carrying the plastic and / or metal waste and a part of the wash water, wherein the washing drum comprises a first discharge and a second discharge respectively for removing the wash water from the washing drum and for removing the plastic and / or metal waste from the washing drum, wherein the shell comprises openings for removing wash water from the shell to the first discharge, wherein the shell is divided into four zones between the inlet and the second discharge, wherein a second zone, a third and a fourth zone comprise the paddles and the openings in the shell, wherein the openings comprise a filter.

10. The apparatus according to claim 9, characterized in that the apparatus comprises a first screen for removing fibers and solid particles from the collected wash water, wherein the first screen is a drum screen, wherein the first screen comprises a supply for introducing the collected wash water onto the first screen, wherein the first screen comprises a screen surface with pores for retaining the fibers and the solid particles from the collected wash water, wherein the firstscreen comprises a first discharge and a second discharge respectively for removing the fibers and the solid particles from the first screen and for removing screened wash water from the first screen.

11. The apparatus according to claim 9 or 10, characterized in that the cleaning installation comprises a hydrocyclone for separating particles with a higher density than water from the collected wash water, wherein the hydrocyclone comprises a supply for introducing the collected wash water into the hydrocyclone, wherein the hydrocyclone comprises a first discharge and a second discharge respectively for removing particle-free wash water to the first decantation tank and for removing said particles with remaining wash water from the hydrocyclone.

12. The apparatus according to claim 11, characterized in that the apparatus comprises a second screen for removing the remaining wash water from the particles, wherein the second screen is a vibrating screen, wherein the second screen comprises a supply for introducing the particles with the remaining wash water onto a screen surface of the second screen, wherein the second screen comprises a first discharge and a second discharge respectively for removing the remaining wash water separated from the particles and for removing the particles from the screen surface.

13. The apparatus according to one of the preceding claims 9-12, characterized in that the cleaning installation comprises one or more settling tanks, wherein at least one settling tank is a lamella separator, wherein the cleaning installation comprises a water tank for storing water from the lamella separator, wherein the lamella separator comprises a supply for introducing the screened wash water, wherein the lamella separator comprises lamellae for retaining and settling fine particles into sludge from the screened wash water, wherein the lamellae are positioned at an angle of at least 45° and at most 75° relative to a horizontal plane, wherein the lamella separator comprises a first discharge and a second discharge respectively for removing the sludge along the lamellae and for decanting water over the lamellae to a water tank.

14. The apparatus according to claim 13, characterized in that the cleaning installation comprises a buffer tank for storing and buffering the sludge, wherein the buffer tank comprises a first inlet for introducing the sludge, wherein thebuffer tank comprises one or more rotatable mixing elements for keeping the sludge in suspension, wherein the buffer tank comprises a discharge for removing the sludge in suspension from the buffer tank.

15. The apparatus according to claim 13 or 14, characterized in that the lamella separator comprises a scraper for removing foam at a free water surface of the lamella separator.

16. The apparatus according to claim 14 or 15, characterized in that the cleaning installation comprises a press for separating wash water from the sludge, wherein the press is a belt filter press or a chamber filter press, wherein the press comprises an inlet for introducing the sludge, wherein the press comprises a filter for retaining filter cake from the sludge and separating the wash water, wherein the press comprises a first discharge and a second discharge respectively for removing the filter cake of the filter from the press and for removing wash water from the sludge from the press to the first decantation tank.

17. The apparatus according to one of the preceding claims 9-16, characterized in that the washing drum comprises an injector for introducing the cleaned wash water and the plastic and / or metal waste, wherein the paddles are transverse connections between successive windings of the spiral, wherein the shell is rotatable by rollers, wherein the rollers are drivable, wherein the spiral is attached to an inner side of the shell, wherein the injector and the second discharge are each located at an opposite end of the shell, wherein the shell comprises openings for removing wash water from the shell to the first discharge.

18. Use of a method according to one of the preceding claims 1-8 and / or an apparatus according to one of the preceding claims 9-17 for cleaning and reusing water originating from a processing process of plastic and / or metal waste, wherein the waste originates from automotive shredder residue, from waste electrical and electronic equipment or from incinerator bottom ash.

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