EP0722777B1 - Method for processing slag from waste incineration plants - Google Patents

Abstract

The method involves raw slag being separated into at least two fractions and the first fraction has a particle size of up to 80 mm, pref. 32 mm in a first phase. The screen overflow from the first phase is supplied to the wet slag separator (4). The through-fall through the screen and through the fire rack is sent to a second screen phase (5) to separate the fine material. The screen overflow from the second phase is mechanically pulverised after sorting out the metal and inert materials and the through-fall from the second phase is sent to a melting furnace (7) for separate processing. A third screen phase (8) can be included.

Description

TECHNICAL AREA

The invention relates to a method for processing of slag from waste incineration plants, in which the raw slag after passing the grate directly and without prior quenching in a water bath in at least two Fractions being separated, and these two fractions separated be treated further, the coarse fraction using a wet detoxifier is fed.

Such a processing method is, for example, from known from EP-0 437 679 B1.

TECHNOLOGICAL BACKGROUND AND PRIOR ART

When municipal waste is incinerated, about 250 kg fall Slag per ton of waste as a waste. The accruing Slag contains pollutants immediately after the furnace on their further use, e.g. as a building material, prevent. The deposition of the slag in landfills leads to a Danger to the environment, if not special precautions be hit, e.g. collecting the leachate.

Usually, the slag is released immediately after the furnace quenched in a wet purifier. Without additional Washing the slag can be lowered of the heavy metal content in the slag and not achieve it considerable amounts of toxins remain in the Slag.

EP-0 437 679 describes a method for treating residues a waste incineration plant known, in which the raw slag after passing through the grate in two Fractions is separated. The rust slag, boiler ash and rust diarrhea separated into two fractions. The fraction with components whose diameter is less than 100 to 300 mm, is melted in a separate melting furnace, the larger components of the grate and boiler ash are introduced into a wet slag remover.

This comparatively rough classification ultimately leads to the fact that components are supplied to the melting furnace that actually do not need such special treatment.

In EP patent 0 372 039 a way is now for the first time for processing slag from waste and incinerators shown, the slag directly after the furnace and without prior deterrence in a water bath Coarse cleaning (removing unburned coarse material and magnetic Parts) is supplied. Then the roughly cleaned Slag separated into at least two fractions and one Fraction assigned to all particles that are smaller than 2 mm.

This known method is based on the knowledge that the fine fraction most of the originally in the Contains slag at the pollutants contained in the slag outlet. It will be given special treatment. The coarse fraction however, is for direct use as a building material or suitable for disposal in landfills.

In the technical implementation of the method according to the EP patent 0 372 039 it now prepares certain technical Difficulties, on the one hand, to separate the fine fraction 0 ... 2 mm - conventional screen conveyors or other classifying devices tend to clog, on the other hand, the air seal be guaranteed against the combustion chamber, and cooling the coarse fraction is also problematic.

SUMMARY OF THE INVENTION

The invention as characterized in the claims is, the task is based on a method of the beginning Specify the type mentioned, the simple separation of the Fine fraction enables air to be sealed off from the combustion chamber and cooling the second fraction with simple Means can be achieved.

• einfache Abtrennung des Feinanteils mit herkömmlichen Klassiereinrichtungen
• einfach durchzuführender Luftabschluss gegenüber dem Verbrennungsraum, und zwar für beide Partikelströme, wobei insbesondere die Nassentschlackung der Grobfraktion um 30 mm mit bewährter Technologie durchgeführt werden kann

Die Erfindung und weitere mit ihr erzielbare Vorteile werden nachstehend anhand eines Ausführungsbeispiels näher erläutert. The invention is based on the idea of separating the fine fraction contaminated with pollutants in a "dry" way and further processing the coarse fraction low in pollutants "wet". This procedure - you could call it "semi-dry detoxification" - offers in combination with the two-stage extraction of the fine fraction 0 ... 2 mm numerous advantages:

• easy separation of the fine fraction with conventional classifying devices
• air can be easily sealed off from the combustion chamber for both particle streams, whereby in particular the wet detoxification of the coarse fraction by 30 mm can be carried out with proven technology

The invention and further advantages which can be achieved with it are explained in more detail below on the basis of an exemplary embodiment.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1

eine aus einzelnen Baugruppen zusammengestellten Anlage zum Aufbereiten von Schlacke aus Müllverbrennungsanlagen;

Fig.2

einen vereinfachten Längsschnitt durch einen Teil einer Müllverbrennungsanlage;

Fig.3

einen mehr ins Detail gegehenden Schnitt durch die erste Siebstufe der Anlage gemäss Fig.2.

In the drawing, an embodiment of the invention is shown schematically; shows

Fig. 1

a system composed of individual assemblies for processing slag from waste incineration plants;

Fig. 2

a simplified longitudinal section through part of a waste incineration plant;

Fig. 3

a more detailed section through the first screening stage of the system according to Fig. 2.

WAYS OF CARRYING OUT THE INVENTION

Waste is burned in an incinerator 1. The one there smoke gases and entrained particles (fly ash as kettle ash and filter ash) are in a known manner a separation and filter stage 2 prepared, for example described and shown in EP-0 437 679 B1 is. The grate ash gets directly from the grate into a first sieve stage 3. This is preferably a sieve conveyor grate educated. Such devices are known and are in addition to other areas of application also in waste incineration plants used to screen the fine fraction (see brochure "Jost sieve conveyor grates" from Jost AG Maschinenfabrik, CH-3627 Heimberg, FOT 1.92 - 3000, undated). In this first one Sieve stage is the separation of the raw slag into one Fine fraction with particle diameters smaller than 25 ... 35 mm and a corresponding coarse fraction. The coarse fraction arrives as Sieve overflow in a wet slag 4 known design. This also provides the air seal on the coarse fraction side safe from the inside of the oven. The fine fraction smaller than 25 ... 35 mm becomes a second sieving stage, e.g. a strainer screen or preferably one Vibrating sieve also of known design, supplied. Optional can the second sieve stage 5 also the rust diarrhea from the Incinerator 1 are supplied, which in the figure by a dashed line is symbolized. The Sieving diarrhea of the second sieving stage 5 with particles from 0 ... 2 mm is specially treated, e.g. melted in a melting furnace 7. The sieve overflow of the second sieve stage 5 is in a grinding stage 6 mechanically crushed, e.g. in a ball mill. In the example, the ground is then Good in a third (optional) screening stage 8, e.g. one Bar sieve, again separated into two fractions, namely one Fine fraction with particle size 0 ... 2 mm and a coarse fraction greater than 2 mm. The fine fraction - it contains compared to Fine fraction 0 ... 2 mm of the second sieving stage 5 fewer pollutants - Is also fed to the melting furnace 7, the Coarse fraction - it essentially only consists of Inert substances - can be deposited. Under certain circumstances a sorting stage between the grinding stage 6 and the third sieving stage 8 9 be interposed in order to already have metal parts, preferably separated according to ferrous and non-ferrous metals, and to discard other inert substances.

The transport of the still very hot sieve diarrhea of the first Screening stage 3 to second screening stage 5 is normally carried out through known funding facilities. Preferably sees here is a further development of the invention, a discharge device, preferably a screw conveyor 10 to provide the cooling and Air sealing functions combined. This screw conveyor 10 also serves as an air seal the fine fraction side of the first sieve stage 3 opposite the incinerator 1 and also acts as a cooling device for the Ash cooling because of the design of a screw conveyor the goods to be conveyed over a large area with the screw conveyors in Comes into contact and the latter can simply be cooled. Should the screw conveyor 10 function as Airlock can prove to be inefficient, this can a double pendulum flap 11, also in the literature double-leaf butterfly valve, can be connected.

As can be seen from FIGS. 2 and 3, this can be described "Semi-dry process" without much effort in a waste incineration plant integrate. In these two figures are only the components that represent the core of the Invention relate to, namely separating the first fraction with a particle size around 30 mm in the first sieving stage and Wet purification of the sieve overflow of this sieving stage.

Burnt out slag 12 (coarse / fine) falls at the end of the grate 13 in a slag shaft 14, the walls of which so far are drawn down that they dip into the wet slag 4. There is one in the side wall of the slag shaft Deflection flap 15 is pivotally arranged. As a rule, this is Deflection flap 15 swung out of its vertical position and closes the direct access to the wet slag remover 4. Burnt-out slag then becomes the first screening stage 3 supplied, which is preferably designed as a sieve conveyor grate is. The sieve overflow of the first sieve stage 3 goes directly into the wet slag remover 4 below the sieve stage 3. The arrangement is taken so that the sieve overflow into one Shaft 16 falls, the walls 17, 18 of which are pulled down so far are that they end below water level 19. On in this way the air is sealed off from the slag shaft 14 and thus reached the inside of the oven.

The sieve diarrhea is in one or more funnels 20, 21 caught under the first sieving stage 3 and over suitable Discharge devices 10, e.g. Screw conveyors or trough chain conveyors, carried out separately and dry and is as in Further described in connection with Fig.1. In the conveyor first screening stage 3, the deflection flap 15 can be vertical be placed (shown in broken lines in Fig. 3), so that the entire slag is discharged conventionally (wet) can.

LIST OF DESIGNATIONS

1

Incinerator

2nd

Separation and filter stage

3rd

first sieve stage

4th

Wet purifier

5

second sieve stage

6

Grinding stage

7

Melting furnace

8th

third sieve stage

9

optional sorting level

10th

Schencken conveyor

11

Double swing flap

12th

burnt out slag

13

rust

14

Slag shaft

15

Deflection flap

16

Shaft

17.18

Walls of 16

19th

Water level in 4

20.21

Collecting funnel

Claims (9)

1. Method for processing slag from waste incineration plants, in which the raw slag, after passing over the firing grate, is separated into at least two fractions in a water bath, directly and without previous quenching, and these two fractions are further treated separately, the coarse fraction being fed to a wet-slag remover (4), characterized in that the first fraction, with a particle size up to 80 mm, preferably up to about 32 mm, is separated in a first screening stage (3), and the screen overflow from the first screening stage (3) is fed to the wet-slag removal means, in that the screen through fraction and, if appropriate, the grate through fraction from the firing grate are fed to a second screening stage (5) for the purpose of separating the fine component 0...2 mm, in that the screen overflow from the second screening stage, if appropriate following the screening out of metallic and inert substances, is comminuted mechanically and the screen through fraction from the second screening stage (5) is fed to a special treatment means, for example a smelting furnace (7).
2. Method according to Claim 1, characterized in that the screen overflow from the second screening stage, after mechanical comminution, is fed to a third screening stage (8), and the fine component 0...2 mm from this third screening stage is likewise fed to a special treatment means, preferably being specially treated together with the screen through fraction obtained in the second screening stage (5).
3. Method according to Claim 1 or 2, characterized in that the first screening stage (3) is integrated into the firing grate of the incineration furnace (1) or directly follows it.
4. Method according to Claim 3, characterized in that a mesh screen conveyor is used as the first screening stage (3) and/or a vibrating screen is used as the second screening stage (5).
5. Method according to Claim 3 or 4, characterized in that the screen overflow from the first screening stage (3) is fed directly to the wet-slag remover (4).
6. Method according to one of Claims 1 to 5, characterized in that the screen through fraction from the first screening stage (3) is transported to the second screening stage (5) by means of a discharge unit (10), which at the same time acts as an air exclusion unit.
7. Method according to Claim 6, characterized in that cooling of the material to be discharged is carried out at the same time in the discharge unit (10) .
8. Method according to Claim 6 or 7, characterized in that the air exclusion is additionally brought about by means of a double swinging flap arrangement (12), which is connected downstream of the discharge unit (10) .
9. Method according to one of Claims 2 to 8, characterized in that a sorting stage (9) is connected in between the second (5) and third (8) screening stages, in order to remove metals, preferably separated into ferrous metals and non-ferrous metals, and other inert materials.

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