EP2668445A2

EP2668445A2 - Processing of waste incineration ashes

Info

Publication number: EP2668445A2
Application number: EP12707240.3A
Authority: EP
Inventors: Alexandra Beckmann
Original assignee: Individual
Current assignee: Mdsu Mitteldeutsche Schlacken Union & Co KG GmbH; SCHAUENBURG MASCHINEN-UND ANLAGEN-BAU GmbH
Priority date: 2011-03-04
Filing date: 2012-03-02
Publication date: 2013-12-04
Anticipated expiration: 2032-03-02
Also published as: DK2668445T3; HUE057566T2; US20140054202A1; LT2668445T; SMT202200061T1; WO2012119739A8; PT2668445T; US20150129466A1; ES2904602T3; PL2668445T3; WO2012119739A3; DE102011013030A1; EP2668445B1; HRP20220100T1; RS62879B1; SI2668445T1; US9216419B2; CY1124946T1; WO2012119739A2

Abstract

The invention relates to a method for processing waste incineration ashes, in particular domestic waste incineration ashes, in which the ashes are classified into a plurality of fractions of different grain size distributions in a processing plant separated from the actual waste incineration process. The ashes are classified exclusively using a wet classification process in the processing plant, only wet classification processes that are gentle to the grains being used, and the wet classification process is performed in such a way that all of the ashes are classified into at least one fine fraction loaded with harmful substances and at least one coarse fraction that contains only a small amount of harmful substances or no harmful substances at all.

Description

PREPARING WASTE BURNER

The invention relates to a method and a device for processing waste incineration ash, in particular household waste incineration ash (HMVA), in which the ash is classified in a treatment plant separate from the actual waste incineration.

A classification of formerly also referred to as slag ash, which arises in the combustion of waste, such as commercial or household waste, is basically known. Classification is understood as meaning a separation of a starting material consisting of particles with a given particle size distribution into a plurality of fractions of different particle size distribution. The classification serves, in particular, to separate the ashes into different proportions of pollutants, some of which can be profitably recycled, while other shares have to be dumped due to existing relevant legislation at the expense of costs. A classification can exploit the fundamentally known fact that certain pollutants bind substantially only to ash particles having a certain maximum grain size.

Despite this knowledge, it has not been possible to prepare waste incineration ash in an economically interesting manner in compliance with legal provisions. Rather, the refuse incineration ash is usually deposited in practice, which, however, is associated with relatively high costs, or utilized under high conditions, for example, as low-classified building material. The object of the invention is therefore to provide a way in which waste incineration ash can be fed to an economically interesting recycling. The solution of this object is achieved by the features of claim 1 and in particular by a method for processing waste incineration ash, in particular domestic waste incineration ash (HMVA), in which it is provided that the ash is separated into a plurality of fractions in a treatment plant separate from the actual waste incineration. Classifying the ash in the processing plant is done exclusively by a wet classification, that in wet classification only grain-sparing classification methods are used, and that the wet classification is carried out such that the ash completely into at least one loaded with pollutants fine fraction and at least one low-emission or pollutant-free coarse fraction is classified.

The invention is based on the finding that in the treatment of waste incineration ash, the concentration of relevant pollutants contained in the ash in a fine fraction, ie in one or more proportions with a relatively low maximum grain size, then economically interesting, if it succeeds Share of this fine fraction on the starting material, so to keep the introduced into the processing ash, as small as possible.

The inventors have recognized that this condition can be fulfilled if care is taken to prevent as much as possible the ash particles from being comminuted during the processing of the ash, since comminution of the ash creates additional surfaces to which pollutants can bind, resulting in that the contaminated with pollutants proportion increases, in such a way so that that portion of the ash, which can not be recycled, but rather must be deposited expensive, is too large.

The invention does not aim at the purpose of modifying the known dry classification, but rather by subjecting the refuse incineration ash to a generally known wet classification. The inventors have recognized that the fact can be exploited that just a wet classification allows the application of particularly grain-friendly classification methods. Grain-sparing classification methods are understood by the person skilled in the art to be those methods in which the particles to be classified are not comminuted or destroyed and in which, in particular, no dust is produced, so that the particle size distribution of the input material overall compared to that of the starting material, ie all fractions formed during the classification , practically unchanged.

This idea of subjecting refuse incineration ash to wet classification, since it is precisely a wet classification which allows a particularly grain-friendly treatment of the ashes, and also to design this wet classification such that an ash fraction comprising one or more fine fractions has a particle size distribution with an upper limit such that this ash fraction is as complete as possible on the one hand contains relevant pollutants and on the other hand, as small as possible, makes it possible that only a relatively small proportion of the ash due to its pollution can not be readily recycled, whereas a comparatively large low-emission or pollutant-free ash content can be recycled. The invention thus provides a possibility for the treatment of refuse incineration ash, in which, in accordance with even strict legal provisions, a significant proportion of the ash can be fed to an economically interesting recycling.

Preferred embodiments of the invention are also set forth in the dependent claims, the description and the drawings.

Preferably, the wet classification is carried out such that in the fine fraction, the lower limit of the grain size is 0 μπι and the upper limit of the grain size is approximately in the range of 50 to 500 μπι, in particular approximately in the range of 200 to 300μπι and preferably about 250μπι. It has been found that with such an upper limit of the grain size practically all relevant pollutants are contained in the fine fraction, at the same time the proportion of these contaminated with pollutants fine fraction of the introduced into the processing plant ash is so small that by the recycling of low-emission or pollution-free rest the ash as a whole an economic treatment of the ash is possible.

In a preferred embodiment of the invention, the wet classification comprises a classification by Aufstromtechnik. A classification by Aufstromtechnik is basically known. The invention can use this type of classification in a particularly advantageous manner, since the ash is treated here extremely grain-friendly. In this case, a hydrocyclone is preferably connected upstream of a upflow classifier.

In a further advantageous embodiment of the invention, the following steps are carried out in succession in the wet classification: First, the ash is mixed with a liquid. From the The resulting product is separated at least a first coarse fraction. In this case, a screening device is used in particular. Subsequently, at least a second coarse fraction is separated from the product freed from the first coarse fraction. In particular, an upflow technique is used. The resulting fine fraction is then withdrawn liquid. In this case, in particular a chamber filter press can be used. A wet classification such that in addition to the fine fraction at least two different coarse fractions are separated, is not mandatory, ie it can also be borrowed only a single coarse fraction separated. However, it has been found that, especially with regard to the operation of the treatment plant and the utilization of the low-emission or pollutant-free fraction of the ash, such a wet classification can be carried out particularly effectively and, above all, is advantageous from an economic point of view.

In a further embodiment of the invention, the ash prior to introduction into the treatment plant of a mechanical, in particular dry pretreatment are subjected, are removed from the ash metal parts and unburned impurities. The ash can be damp. Such preparatory treatment of the ashes from the waste incineration plant can - although it can be carried out dry or, for example, in wet ash - nevertheless carried out so gentle on the grain that the particle size distribution of the introduced into the processing plant according to the invention is not adversely affected. As mentioned elsewhere, it is particularly advantageous with regard to an optical sighting of metals for the purpose of separating the metals, and thus a preferred embodiment of the invention, if the separation is not carried out dry, but the metals are "washed in" first , According to one aspect of the invention, the wet classification can be carried out such that the dry weight fraction of the pollutant-contaminated fine fraction at the ash introduced into the treatment plant, from which metal parts and unburned contaminants have been removed in a pretreatment, is at most about 30% and in particular at most about 10%. is. So far, it has not been considered possible to treat waste incineration ash such that only at most about 10 to 30% of the ash is contaminated with pollutants and thus at least about 70 to 90% of the ashes readily and in particular without violation of relevant legislation for recycling can be. However, the grain-sparing wet classification of the ash according to the invention makes exactly this possible.

The ash originating from the waste incineration plant is preferably pretreated in such a way that the ash having a particle size distribution is introduced into the treatment plant whose upper limit is not more than about 100 mm. In particular, the upper limit is in the range of 40 to 50 mm. Preferably, the upper limit is about 45 mm. With such an upwardly limited particle size distribution, to which the invention is nevertheless not limited, the preparation of the ash according to the invention can be carried out in a particularly effective and, as a result, economical manner.

The treatment plant preferably has a substantially closed fluid circuit. In particular, water or an aqueous solution is used as the wet classification liquid. In one possible embodiment of the invention, it may be provided that at least one parameter of a liquid used for wet classification is kept below or above a predetermined limit value. In particular, liquid is discharged from a liquid circuit as soon as the limit value is reached, in particular exceeded or undershot.

This refinement can be of practical significance, on the one hand, if costs are to be saved and, on the other hand, it is to be prevented that certain constituents are "dragged" onto the ashes. Such constituents may in particular be salts, for example mainly chlorides and sulfates. The concentration of these components can be determined, for example, by measuring the conductivity in the liquid, ie. H. the monitored parameter in the fluid circuit may be, in particular, the electrical conductivity. Accordingly, liquid is discharged from the circuit only when the conductivity has reached the predetermined limit. As a result, on the one hand, the consumption of fresh liquid, especially water, minimized, thereby saving costs. On the other hand, it is prevented that the or each low-emission or pollution-free coarse fraction contains too high a proportion of the respective constituents, in particular of salts. The limit value can in particular be made dependent on the wishes of the respective plant operator or specified by the sewage treatment plant on site.

In particular, a liquid used for wet classification has a temperature in the range of 20 to 40 ° C.

According to one aspect of the invention, a method for treating waste incineration ash, in particular waste incineration ash, is disclosed. see (HMVA), provided in which the ash is classified in a separate from the actual waste incineration treatment plant by wet classification completely in a contaminated with pollutants share and a low-emission or pollutant-free fraction.

The wet classification according to the invention can in particular be carried out in such a way that the contaminated with pollutants share of the introduced into the processing plant ash from which were removed in a particular dry pretreatment metal parts and unburned impurities, a dry weight fraction of about 30%, in particular of about 10%, does not exceed. If it is assumed that waste incineration ash, at least when it has been removed in a particularly dry pretreatment of metal parts and unburned impurities, is at least substantially the same in terms of particle size distribution and the type and amount of relevant pollutants, then the ash preparation according to the invention can consequently are characterized by the upper limit of the dry weight fraction of the pollutant-laden ash fraction mentioned here. In particular, the wet classification is carried out such that in the contaminated with pollutants, the lower limit of the grain size is 0 μιη and the upper limit of the grain size is approximately in the range of 50 to 500 μηι, in particular approximately in the range of 200 to 300μπι and preferably about 250μπι ,

According to a further embodiment of the invention, the treatment of the ash according to the invention at one or more points may include a metal treatment, ie the separation of metals. This preparation can be both a FE separation, ie a separation of ferrous metals, as well as a NE separation, ie a separation of Non-ferrous metals, include. Consequently, classic FE or NE separators can be used for this treatment. Alternatively or additionally, an optical sighting can take place. This optical sighting can be done both manually and mechanically. In principle, numerous variants are conceivable, each of which enables a sorted metal treatment.

Preferably, the metal treatment is carried out on one or each pollutant-free or low-emission coarse fraction prior to their Aufhaidung.

In particular, the separation of the metals does not take place dry before or after the wet classification of the HMVA, but after passing through at least part of the wet classification. In other words, the metals are run in the wet or wash process, i. the metals are washed away. This has the advantage that the metals become very clean, i. the metals become so pure by washing that they can be visually recognized by their respective color, thereby improving or even enabling visual inspection of the metals - manually or mechanically. The yield of metals is also increased by this "co-washing". The ride of the metals in Nassbzw. Washing process, i. the "co-washing" of the metals, can also be done if the separation of the metals, no matter whatsoever optical sighting takes place. The "mitgewaschenen" metals can also be separated in a conventional conventional manner by means of known metal separator.

In this way, the efficiency of the ash treatment can be significantly increased. The object is also achieved by a device for processing waste incineration ash, in particular household waste incineration ash (HMVA), with which the ash can be classified into a plurality of fractions of different particle size distribution, wherein a treatment plant is provided, which leads to an exclusive wet classification of the ash is formed, wherein the treatment plant comprises only grain-sparing classifying devices, and wherein the treatment plant is designed such that the ash is completely classifiable into at least one contaminated with pollutants fine fraction and at least one low-emission or pollution-free coarse fraction.

In particular, the device is designed for carrying out a method of the type specified here. Preferably, the treatment plant is designed such that in the fine fraction, the lower limit of the grain size is 0 μιη and the upper limit of the grain size is approximately in the range of 50 to 500 μπι, in particular approximately in the range of 200 to 300μπι and preferably about 250μπι.

The treatment plant may have at least one substantially closed fluid circuit.

The treatment plant preferably comprises a mixing stage in which the ash is mixed with a liquid, in particular with water or an aqueous solution.

Preferably, the treatment plant comprises at least one classification stage, in particular a screening device, in which a previously created which product, in particular from the ash mixed with a liquid, at least one coarse fraction is separated.

Alternatively or additionally, the treatment plant may comprise at least one classification stage, in particular an upflow classifier, in which at least one fine fraction is separated from a previously formed product, in particular from a product freed from at least one coarse fraction. The classifier stage may include an upstream classifier with upstream hydrocyclone.

Furthermore, it can be provided that the treatment plant comprises a dehumidification stage, in which a previously formed product, in particular a fine fraction, liquid is withdrawn. The dehumidifying stage may comprise a chamber filter press, wherein in particular the chamber filter press is preceded by a lap thickener and an eccentric pump.

In a preferred embodiment of the apparatus, a mixing stage, two classification stages and a dehumidification stage of the treatment plant are arranged one behind the other in the process direction, wherein in the first classification stage a coarse fraction with a lower limit for the particle size in the range of 2 to 5 mm, in particular of about 4 mm, separated is, wherein the remaining product of the second classification stage is supplied, in which a coarse fraction having a lower limit for the grain size in the range of about 50 to 500 μπι, in particular approximately in the range of 200 to 300μπι and preferably from about 250μπι, separated, and wherein the remaining fine fraction is fed to the dehumidifying stage. While hitherto, in practice, the HMVA has usually been deposited over a relatively long period of, for example, three months before starting treatment or treatment, it is preferably provided according to the invention that the processing or treatment of the ash commences comparatively early after its formation becomes. This has the advantage that a recognized as disadvantageous sticking or Vereedem the ash is not or only to a non-critical extent. On the other hand, stored ashes tend to stick or sinter, due to the chemical reactions that occur during storage. Adhesive ash must be separated before or during treatment or treatment only with "heavy equipment", ie with just not-conserving mechanical effort. Also, a storage of the ash has the consequence that contained metals can be strongly associated with ash, which makes a visual inspection of the metals difficult or impossible. Early treatment or treatment of the HMVA in a wet process can not result in disadvantageous sticking or sintering of the ash or shorten the disadvantageous chemical reactions. After this treatment or treatment, it can therefore no longer come to a disadvantageous sticking or sintering of the ash.

The invention is described below by way of example with reference to the drawing, whose single figure shows schematically an embodiment of a device according to the invention, in which a method according to the invention can be carried out.

The device according to the invention comprises a treatment plant 11 with various facilities, which will be described in more detail below. The treatment plant 11 is independent of the actual waste incineration. In particular, the treatment plant 11 can be connected to a built in any place and operated separately from a waste incineration plant, but this is not mandatory and in principle an integration into a waste incineration plant is possible. With the system 11 according to the invention, it is possible to treat the combustion ash as produced in the waste incineration in the manner explained below. In particular, any kind of pretreatment or preparatory treatment of ash A is not absolutely necessary. Nevertheless, a preferred embodiment of the invention provides that the refuse incineration ash prior to introduction into the treatment plant 11 is subjected to a particularly dry pretreatment in which metal parts and unburned impurities are removed from the ash. The treatment process according to the invention and the treatment plant 11 according to the invention are particularly suitable for the treatment of domestic refuse incineration ash. However, the invention is not limited thereto. In principle, it is also possible to treat other combustion residues in the manner according to the invention, for example ash or slag, which is produced during the incineration of commercial waste.

In the illustrated embodiment of the invention, the introduced into a mixing stage 21 of Appendix 11, previously freed of metal parts and unburned impurities ash A is separated into three fractions I, II and III, namely a fine fraction I and two coarse fractions II and III. The coarse fractions II and III are at best still low with

Pollutants are loaded and can be stored on stockpiles 29, 31, before they are sent for recycling. At least the majority of the pollutants originally contained in the ash A is located in the Fine fraction I, which can not be readily recycled and stored, for example, in a landfill 33.

The pollutants usually contained in municipal waste incineration ash (hereafter HMVA) are known in principle. Examples include sulfate, chloride, anhydride and TOC (total organic carbon). With regard to the anhydride it should be mentioned that it is also counted among the pollutants in view of a possible recycling of HMVA, for example in road construction, because it considerably increases its volume by absorbing water, i. swells, and thus can develop explosive effect, which can lead to the destruction of the structures concerned.

In the plant 11 according to the invention, the treatment of the ash A by wet classification takes place.

For this purpose, the ash A is mixed in the mixing stage 21 with a liquid. Preferably, water W is used as the liquid. With regard to a particularly advantageous embodiment of the preparation according to the invention, which will be discussed in more detail below, a specific aqueous solution is used as the liquid, namely an acidic aqueous solution. For the sake of simplicity, the liquid used herein will be referred to simply as "water" or "solution" hereinafter. The mixing of the ash A with the water can be done in the sense of soaking or mashing. Accordingly, the mixer 21 may also be referred to as a soaker or macerator.

The mixing of the ash A in the mixing stage 21 takes place in a grain-sparing manner, in order to reduce the size of the introduced ash particles at least largely avoided. If provided at all, a mechanical effect on the ash A in the mixing stage, for example by means of a vibration actuator. A grain-sparing treatment of ash A is not only in the

Mixing stage 21. Rather, the entire system 11 is designed for a grain-friendly ash treatment. As already mentioned, the expert is familiar with the term "grain care". In particular, this is understood to mean that such devices or process steps are neither deliberately used nor accepted, in which the ash particles are comminuted. Of course, a grain-sparing treatment does not exclude that initially only adhering ash particles are separated from each other. In this context, it should be mentioned that the person skilled in the art is aware of fundamentally different wet classification methods which can be described as being gentle on the grain, but the person skilled in the art also knows those methods which can be used in a wet classification and which are aware of a comminution of the particles to be classified bring about or accept. As an example, mention should be made of the so-called sword wash. The use of such non-grain gentle methods of wet classification according to the invention deliberately not. The water supplied to the mixer 21 is provided by a closed water circuit W. The term "closed", of course, does not exclude replacing used liquid and, as provided in the embodiment described herein, liquid for additional recovery as discussed below of phosphates P can also be taken without recycling in the circuit W.

For the preparation of the mentioned acidic environment of the mixing stage 21 is also fed to an acid S, which is in particular comparatively inexpensive available citric acid or sulfuric acid. In the liquid circuit W mentioned, the preferred embodiment of the invention described here is thus a cycle of an acidic aqueous solution. For the wet classification according to the invention per se, an acidic environment is neither absolutely necessary nor disadvantageous, since all relevant parts of the plant can be designed without problems in an acid-resistant manner.

The mixed with the water, i. the soaked or mashed ash A, which still contains all three fractions I, II and III mentioned at the beginning, is then fed to a first classification stage 17, which is a screening device designed so that all ash particles having a particle size of be separated more than 4 mm. In this first classification stage 17, the ashes are brewed with water W originating from the mentioned cycle and sieved off at the 4 mm mentioned.

With regard to the particle sizes of the ash particles mentioned in connection with the explanation of this exemplary embodiment, it is provided here that metal parts and unburned impurities are removed in the case of a particularly dry pretreatment of the ash from the waste incineration plant, whereby this pretreatment takes place in such a way that the particle size distribution the ash A introduced into the mixing stage 21 has an upper limit of about 45 mm. The first coarse fraction III separated by means of the first classification stage 17 thus has a particle size distribution of about 4 to 45 mm. This coarse fraction III is led out of the plant 11 and stored on the already mentioned heap 29.

The remaining ash content with a particle size distribution of about 0 to 4 mm, which thus contains the fine fraction I mentioned at the beginning and the further coarse fraction II, is then fed to a second classification stage, which comprises an upstream classifier 15 with an upstream hydrocyclone 13. Such arrangements are generally known, so that the structure and operation of this second classification stage is not discussed in more detail. It should be emphasized that both in a hydrocyclone and in an upflow classifier, the particles to be classified are treated extremely gently. This means that the particle size distribution of the ash fraction coming from the first classifying stage 17 is practically unchanged even by the second classifying stage 13, 15.

In the exemplary embodiment explained here, the second classifying stage 13, 15 is designed or set in such a way that a second coarse fraction II having a particle size distribution in the range from 0.25 mm to 4 mm is separated from the introduced product. This coarse fraction II is fed to a screening device 35, which can be, for example, a so-called "screen" comprising two screen decks, the material being brewed with water W on the upper screen deck and dewatered on the lower screen deck the water W is removed from the mentioned cycle and fed back to this cycle. The further coarse fraction II dehydrated in this way is subsequently led out of the plant 11 and stored on the already mentioned heap 31. As mentioned above, the second classification stage 13, 15 is set such that after the separation of the second coarse fraction II, the remaining fine fraction I has an upper limit of the particle size of about 0.25 mm, ie of about 250 μm. The design of the system 11 and in particular the second classification stage 13, 15 such that this upper limit for the grain size of the fine fraction I is exactly maintained, is not mandatory. In particular, depending on the introduced ash A and in particular on the type and amount of contained therein, to be concentrated in the fine fraction I pollutant upper limit for the grain size of the fine fraction I is selected such that it is ensured that - tolerable residual - all relevant pollutants bind to the fine fraction I forming particles. In particular, this upper limit is chosen such that it is neither too low, since otherwise the next higher coarse fraction is burdened with pollutants to intolerable extent, is still too high, otherwise the dry weight fraction of the fine fraction I on the introduced ash A is unnecessarily large ,

In this way it is achieved that all relevant pollutants of the introduced into the plant 11 ash A are in the fine fraction I, which is also miriimiert in terms of their dry weight fraction of the introduced ash A. The canned coarse fractions III and II are insofar freed from at least a large part of the pollutants and can be recycled in accordance with the respective applicable statutory provisions, for example in road construction, fed. The fine fraction I coming from the second classification stage 13, 15 is subsequently removed from liquid in a round thickener 23. Subsequently, the fine fraction I is fed by means of an eccentric pump 25 to a chamber filter press 19. Instead of a chamber filter press, for example, a cyclone may be provided to further dehydrate the fine fraction I. However, the use of a chamber filter press has been found to be particularly advantageous.

The fine fraction I led out of this dehumidifying stage formed by the circular thickener 23, the eccentric pump 25 and the chamber filter press 19 has been dehumidified to such an extent that it is puncture proof and can thus be disposed of. The water W produced in this dehumidification stage is returned to the circulation.

Experiments have shown that the manner described here of a wet classification of HMVA with an upper limit of the original particle size distribution of about 45 mm results in a fine fraction I with grain sizes up to 0.25 mm, the fine fraction I contains all relevant pollutants and the only about 10% of the dry weight of the ash A introduced in Annex 11. This means that with the two resulting coarse fractions III and II, a dry weight fraction of about 90% of the ash A introduced into the plant 11 can be utilized without difficulty, since these coarse fractions III and II are low in pollutants or free of pollutants.

Already on account of this recycling facility for refuse incineration ash, which up to now has not been considered feasible, the practical realization of the invention, despite the costs for construction and operation the processing plant 11 according to the invention economically highly interesting. In addition, the operators of incineration plants have an interest in not having to provide themselves for a proper disposal of incineration ash, because until now, this disposal is done by landfilling or high-cost associated utilization of all ashes generated during waste incineration, due to contained pollutants and the relevant legal provisions is associated with high costs. Consequently, the operators of incinerators are willing to pay for the decrease in incineration ash to the complicated

Handling does not have to take over. The economy of the ash treatment according to the invention is further increased, since already the adoption of the ash to be introduced into the treatment plant can be associated with revenue. If the abovementioned pretreatment of the ashes originating from the waste incineration plant is carried out at all for the removal of metal parts and / or uncombusted impurities, this pretreatment does not preclude the economy of the procedure according to the invention. In addition, in the exemplary embodiment of the invention described here, the economy of the ash treatment is further increased by extracting substances from the ash A introduced into the plant, which in turn can be recycled. This use of the ashes, in particular the recovery of phosphates explained below, independently of the wet classification of the ash A, represents an independent, separately claimable aspect of the invention.

As mentioned, this further use of combustion ash in the embodiment described herein relates to the recovery of Phosphates P. Here, the fact is exploited that in the wet classification described above, the ash A already interacts with a liquid. In particular, the closed liquid circuit W has the consequence that the liquid can interact relatively long and intensively with the ash A, which is utilized according to the invention.

By a suitable choice of the liquid can thus be a return of contained in the introduced ash A phosphates P, these phosphates P can be isolated again in a further process step.

As already mentioned above, in the preferred embodiment, the liquid used for the wet classification is water W, which is enriched in the mixing stage 21 with acid S, in particular with citric acid or sulfuric acid. The mixing or soaking or maceration of the ash A with the liquid during the wet classification thus simultaneously constitutes a treatment of the ash A with an acidic aqueous solution, which results in a re-dissolution of the phosphates P contained in the ash A.

In the context of the wet classification of ash A described here, for which an acidic environment is not mandatory, but also not disadvantageous, since all relevant plant components are designed to be acid-resistant, this type of recovery of phosphates P is particularly advantageous since the mixing of Ash A with the water or the acidic aqueous solution and in particular the closed liquid circuit allows a particularly long-lasting and intimate reaction of the ash A with the acidic aqueous solution. Generally speaking, this combination - word for word - thus includes the wet classification of waste incineration ash integrated recovery of recyclable materials, especially phosphates - also an independent, independent and separately claimable aspect of the invention. The re-dissolution of the phosphates P is favored by a higher temperature of the acidic aqueous solution, without thereby affecting the wet classification. Taking into account the energy input required for the heating of the liquid and the associated costs, the temperature is chosen so that the system can be driven overall in an economic optimum range. It has been found that this is possible even at a temperature of the acidic aqueous solution in the closed loop in the range of 20 to 40 ° C. The removal of liquid, including the phosphate P released therefrom, hereinafter also referred to as solution L, can easily be done during the ongoing wet classification operation.

In principle, an ongoing removal of the solution L is possible. Alternatively, it can be provided that only at certain points in time a certain amount of the solution L is taken from the circuit W. These times can be selected in particular as a function of the pH of the circulating liquid. The removal of the solution L contained in the redissolved phosphates P can in principle take place at any point in the liquid circuit W. For this purpose, a removal device can be provided which can be controlled or regulated as a function of the pH of the solution L. The solution L is fed to an isolating device 27 in which, in a basically known manner, the phosphates P are precipitated back. The remaining after the isolation of the phosphates P liquid is fed back to the circuit W.

In this way, with the phosphates P, which are isolated from the solution L taken from the circuit W, a valuable raw material, which in turn can be supplied to a profitable use. Since the reprecipitation of phosphates from a solution, including processes and facilities to be used in this case is basically known, this will not be discussed in detail here.

In principle, according to the invention, it is also possible, alternatively or in addition to phosphates, to recover other substances from the combustion ash by making use of the wet classification and thus the circumstance that, due to the already intensive contact of the ash with a liquid, a re-dissolution of in the ash If necessary, the liquid used in the wet classification is suitably enriched. This recovery of recyclable materials from refuse incineration ash treated with a suitable liquid also independently of a wet classification of the ash constitutes an independent, separately claimable aspect of the invention.

In the embodiment shown in the figure, a measuring device in the form of a potentiometric probe 41 is connected in front of the round thickener 23, with which the electrical conductivity of the liquid can be measured. If the conductivity reaches a predetermined value, for example, by the operator of the treatment plant or the sewage treatment plant can be specified locally, so a predetermined amount of liquid is discharged and replaced by fresh liquid, especially fresh water. The water discharge E can - as shown by way of example in the figure - seen in the process direction behind the lap thickener 23 done.

Furthermore, it is provided in the embodiment shown here that before the heating of the two coarse fractions II, III, respectively, a metal processing 37, 39 takes place. This can be done in different ways depending on the circumstances and requirements, as already mentioned by way of example in the introductory part. The metal treatment is preferably carried out in such a way that the metals before their separation in the wet or washing process, ie, "washed along", so that an optical sighting improved or even made possible, as by this ride of the metals in the wet process, the metals be particularly clean.

LIST OF REFERENCE NUMBERS

11 Processing plant 13 Hydrocyclone

15 upstream classifiers

17 screening device

19 chamber filter press

21 mixing stage

23 round thickener

25 eccentric pump

27 insulation device

29 heap

31 heap

33 landfill

35 screening device

37 Metal processing

39 Metal processing

41 measuring device

A ash

I fine fraction

II coarse fraction

III coarse fraction

W water, water cycle

L aqueous solution

S acid

P phosphates

E water discharge

Claims

claims

Process for treating waste incineration ash (A), in particular household waste incineration ash (HMVA),

in which the ash (A) is classified into a plurality of fractions (I, II, III) of different particle size distribution in a treatment plant (11) separate from the actual waste incineration, characterized

that in the treatment plant (11) the classification of the ash (A) is carried out exclusively by a wet classification,

that in wet classification only grain-sparing classification methods are used, and

the wet classification is carried out in such a way that the ash (A) is completely classified into at least one fine fraction (I) loaded with pollutants and at least one low-pollutant or pollutant-free coarse fraction (II, III).

Method according to claim 1,

characterized,

the wet classification is carried out in such a way that the lower limit of the grain size is Ομπι in the fine fraction (I) and the upper limit of the grain size is approximately in the range of 50 to 500μπι, in particular approximately in the range of 200 to 300μπι and preferably about 250μπι.

Method according to claim 1 or 2,

characterized,

in that the wet classification comprises a classification by upflow technology, wherein in particular an upstream classifier (15) is preceded by a hydrocyclone (13). Method according to one of the preceding claims, characterized

that during wet classification, the following steps are performed one after the other:

the ash (A) is filled with a liquid (W), in particular

Water, mixed,

from the resulting product at least a first coarse fraction (III) is separated,

in particular using a sieve device (17), from the product freed from the first coarse fraction (III), at least a second coarse fraction (II) is separated, in particular using an upflow technique, the resulting fine fraction (I) is withdrawn liquid (W),

in particular using a chamber filter press (19).

5. The method according to any one of the preceding claims,

characterized,

that the ash (A) prior to introduction into the treatment layer (11) is subjected to a mechanical, in particular dry pretreatment, in which from the ash (A) metal parts and un burnt contaminants are removed.

Method according to one of the preceding claims,

characterized,

the wet classification is carried out in such a way that the dry weight fraction of the pollutant-laden fine fraction (I) at the ash (A) introduced into the treatment plant (11) is which were removed in a pretreatment of metal parts and unburned impurities, at most about 30%, in particular at most about 10%.

Method according to one of the preceding claims,

characterized,

the ashes from the incinerator are pretreated such that the ash (A) having a particle size distribution is introduced into the treatment plant (11) whose upper limit is not more than about 100 mm, in particular the upper limit being in the range of 40 to 50 mm and preferably about 45mm.

Method according to one of the preceding claims,

characterized,

in that the treatment plant (11) has a substantially closed liquid circuit, in particular water (W) or an aqueous solution (L) being used as liquid for the wet classification.

Method according to one of the preceding claims,

characterized,

a liquid (W), in particular water, used for the wet classification has a temperature in the range from 20 to 40 ° C.

Method for treating refuse incineration ash (A), in particular household refuse incineration ash (HMVA), in which the ash (A) is completely separated into a refining plant (11) separated from the actual refuse incineration plant by wet classification contaminated with pollutants share (I) and a low-emission or pollutant-free fraction (II, III) is classified.

Method according to claim 10,

characterized,

in that the wet classification is carried out in such a way that the pollutant-loaded fraction (I) on the ash (A) introduced into the treatment plant (11) from which metal parts and unburned contaminants have been removed in a mechanical, in particular dry pretreatment, has a dry weight fraction of at most about 30%, in particular at most about 10%.

Method according to claim 10 or 11,

characterized,

in that the wet classification is carried out in such a way that the lower limit of the particle size is inμπι in the contaminated with pollutants (I) and the upper limit of the grain size is approximately in the range of 50 to 500μπι, in particular approximately in the range of 200 to 300μπι and preferably about 250μπι is.

Method according to one of the preceding claims,

characterized,

that at least one parameter, in particular the electrical conductivity, of a liquid used for wet classification, in particular water or an aqueous solution, is kept below or above a predetermined limit value, wherein in particular liquid is discharged from a liquid circuit as soon as the limit value is reached, in particular exceeded or falls below. Apparatus for treating waste incineration ash (A), in particular household waste incineration ash (HMVA),

with which the ash (A) can be classified into a plurality of fractions (I, II, III) of different particle size distribution, in particular for carrying out a method according to one of the preceding claims,

characterized,

that a treatment plant (11) is provided, which is designed for an exclusive wet classification of the ash (A), that the treatment plant (11) comprises exclusively grain-sparing classifying devices, and

the treatment plant (11) is designed such that the ash (A) can be completely classified into at least one fine fraction (I) loaded with pollutants and at least one low-coarse or pollutant-free coarse fraction (II, III).

Device according to claim 14,

characterized,

that the treatment plant (11) is designed such that in the fine fraction (I) the lower limit of the grain size is Ομπι and the upper limit of the grain size is approximately in the range of 50 to 500μπι, in particular approximately in the range of 200 to 300μπι and preferably about 250μπι is.

Apparatus according to claim 14 or 15,

characterized,

the treatment plant (11) has at least one substantially closed liquid circuit.

17. Device according to one of claims 14 to 16,

characterized,

in that the treatment plant (11) comprises a mixing stage (21) in which the ash (A) is mixed with a liquid (W), in particular with water or an aqueous solution (L).

18. Device according to one of claims 14 to 17,

characterized,

in that the treatment plant (11) comprises a classification stage (17), in particular a screening device in which ashes (A. A) are mixed with a previously formed product, in particular with the liquid (W), in particular with water or an aqueous solution (L) ), at least one coarse fraction (III) is separated off.

19. Device according to one of claims 14 to 18,

characterized,

in that the treatment plant (11) comprises a classification stage (13, 15), in particular an upflow classifier, in which at least one fine fraction (I) is separated off from a previously formed product, in particular from a product freed from at least one coarse fraction (III).

20. Device according to claim 18 or 19,

characterized,

in that the classifying stage comprises an upstream classifier (15) with an upstream hydrocyclone (13). Device according to one of claims 14 to 20, characterized

in that the treatment plant (11) comprises a dehumidification stage (23, 25, 19) in which liquid (W) is withdrawn from a previously formed product, in particular a fine fraction (I).

Device according to claim 21,

characterized,

in that the dehumidification stage comprises a chamber filter press (19), wherein in particular the chamber filter press (19) is preceded by a lap thickener (23) and an eccentric pump (25).

Device according to one of claims 14 to 22,

characterized,

a mixing stage (21), two classification stages (17, 13, 15) and a dehumidification stage (23, 25, 19) of the treatment plant (11) are arranged one behind the other in the process direction,

wherein in the first classification stage (17) a coarse fraction (III) having a lower limit for the particle size in the range of 2 to 5 mm, in particular of about 4 mm, is separated off,

the remaining product of the second classification stage (13, 15) is supplied, in which a coarse fraction (II) with a lower limit for the grain size approximately in the range of 50 to 500μπι, in particular approximately in the range of 200 to 300μπι and preferably from about 250μπι separated will, and

the remaining fine fraction (I) is fed to the dehumidifying stage (23, 25, 19).