METHOD FOR PRODUCING A BINDER FOR THE CONDITIONING OF SLUDGES, SOILS CONTAINING WATER AND FOR THE NEUTRALIZATION OF ACIDS

Abstract

The invention relates to a method for producing a binder from slag for conditioning sludges/dredged material, soils containing water and for the neutralization of acids. According to the invention, the slag from a waste incinerator is crushed, then metal is removed and the crushed slag is graded into a fraction greater than 2.0-3.0 mm and a fraction smaller than 2.0-3.0 mm, the fraction 0/2.0-0/3.0 mm is dried in a dryer to a terminal humidity less than 1.5 wt. %-2.5 wt. %, as a result of which the pozzolanic properties of the slag are reactivated, the yield from the dryer is further crushed in a high-speed impact mill to a stable cubic grain structure and the metal released in this process is removed, and the 0/500-0/750 m fraction forming the binder is separated from this crushed slag.

Claims

1. A method for producing a binder from slags from municipal waste incineration plants (MWIP slags) for the conditioning of sludges, soils containing water and for the neutralization of acids, wherein the slag (11) from a waste incineration plant is crushed, the crushed slag is graded into a fraction greater than 2.0 to 3.0 mm and a fraction smaller 2.0 to 3.0 mm, the separated smaller fraction 0/2.0 or 0/3.0 mm is dried in a dryer (18) to a terminal humidity of less than 1.5 wt. %-2.5 wt. %, as a result of which the pozzolanic properties of the slag are maintained, the yield of the dryer is further crushed, and the 0/500 m to 0/750 m fraction forming the binder (28) is separated from this crushed slag.

2. The method according to claim 1, wherein the slag is stored for about 2.5 to 3.5 months before the first crushing.

3. The method according to claim 1, wherein before drying, the metal-containing substances are at least partially removed by digestion from the crushed slag.

4. The method according to claim 1, wherein the drying of the separated smaller fraction 0/2.0 mm to 0/3.0 mm is performed in a drum dryer (18).

5. The method according to claim 4, wherein the drying is carried out by the direct co-method.

6. The method according to claim 4, wherein the drying is carried out at a temperature in the drum of 270 C. to 330 C.

7. The method according to claim 1, wherein after drying, the metal-containing substances are at least partially removed by digestion from the smaller fraction 0/2.0 to 0/3.0 mm

8. The method according to claim 1, wherein after drying, crushing to a stable cubic grain structure is carried out with a high-speed impact crusher or a high-speed impact mill (21).

9. The method according to claim 1, wherein the filter dust from the drying is supplied to the binder.

10. A binder consisting of a fraction smaller than 500-750 m of slag from waste incineration plants which has been treated by the method according to claim 1.

11. A landfillable substance mixture consisting of a wet, solid sludge/dredged material to which the binder produced by the method according to claim 1 has been added and mixed/conditioned therewith.

12. The landfillable substance mixture according to claim 11, wherein the binder content is between 10 wt. % and 40 wt. %.

13. Use of the binder prepared by the method according to claim 1 for the neutralization of acidic wastes.

Description

[0024] The invention will be explained in more detail below with reference to the schematic drawing. The sole figure shows a method scheme according to the invention.

[0025] The slag 11 originating from a waste incineration plant is first stored in an interim storage facility 12 for a predetermined time of 2.5 to 3.5 months. Subsequently, the slag is crushed in a first crushing device, for example in an impact mill 13. Metallic components are separated from the crushed slag in a separation device 14 known per se. Ferrous metals can be separated using magnetic separators. These metals 15 are sent for further use.

[0026] The slag thus cleaned of metals passes into a first grading station 16, in which the slag is graded into a fraction greater than 3.0 mm and a fraction less than 3.0 mm. The fraction 17 greater than 3.0 mm is discharged for another use.

[0027] The fraction smaller than 3.0 mm is fed to a drum dryer 18, in which the slag is dried by the co-current method to a residual moisture content of <1.5 wt. % to <2.0 wt. %. The temperature at the burner 19 is about 600 C., while the temperature in the drum is about 300 C. The drying process at these temperatures reactivates the pozzolanic properties of the slag. The water vapor 20 produced during drying is drawn off with a filter system (not shown).

[0028] The solid discharge of the drying is further crushed in a second crushing device 21. This can be done, for example, in a high-speed impact mill where the fissured unstable sintered conglomerates are crushed to form stable cube-shaped particles. Also, a blasting of the particles can take place with release of the metals contained therein.

[0029] The slag crushed in this way is fed to a further metal separation apparatus 22. Here, the non-ferrous metals and the ferrous metals 23 are removed from the slag and sent for further use.

[0030] The remaining slag is then separated in a second grading apparatus 24 into a fraction greater than 750 m and a fraction smaller than 750 82 m. The fraction 25 greater than 750 m is discharged for another use.

[0031] The fraction 0/750 m has the desired pozzolanic properties and grain structures. This fraction is mixed in a mixing device 26 with the filter dust 27 from the filter unit of the drying device 18. This mixture forms the binder 28.

[0032] The binder 28 can be mixed with dredged material in a mixing plant and then transported to a landfill site. There, the substance mixture made of dredged material and binder hardens. Due to the setting, there is no longer the risk that water will escape or that environmentally-polluting substances will be washed out.