METHOD AND DEVICE FOR WASHING/CLEANING GRANULAR MATERIAL FROM SLAG AND WASHING/CLEANING BOTTOM/BOILER ASH FROM A THERMAL WASTE TREATMENT, AND MINERAL RESIDUE AND RECYCLING MATERIAL

Abstract

The invention relates to a method for washing/cleaning granular material from slag and for washing/cleaning bottom/boiler ash from a thermal waste treatment. In the method, the granular material is added to a process liquid and is subjected to ultrasound therein. According to the invention, it is proposed that the process liquid is located in an upright cleaning channel with an upper feeding end and a lower extraction end, that the granular material is introduced into the cleaning channel from the feeding end, and moves downwards towards the extraction end due to the force of gravity, and is subjected to ultrasound during the sinking movement.

Claims

1. A method for washing/cleaning granular material from slag as well as bottom/boiler ash from a thermal waste treatment as well as mineral residue and recycling material, wherein in such method the granular material is added to a process liquid and is subjected to ultrasound therein, and wherein said process liquid is located in an upright or vertical cleaning channel (12) with an upper feeding end (13) and a lower extraction end (14), that the granular material is delivered from the feeding end (13) into the cleaning channel (12) and moves downwards towards the extraction end (14) due to the force of gravity and is subjected to the ultrasound during the sinking movement.

2. The method according to claim 1, wherein said cleaning channel (12) is flown through from the bottom to the top by the process liquid and the liquid escaping from the feeding end (13) is extracted via an overflow (28).

3. The method according to claim 2, wherein the process liquid has a consistent or pulsating flow rate during processing.

4. The method according to claim 3, wherein such flow rate of said process liquid in the cleaning channel (12) is chosen such that the granular material to be cleaned is retained in the cleaning channel (12) and is not extracted from the feeding end into the overflow.

5. The method according to claim 2, wherein during processing, said process liquid is moved through the cleaning channel (12) at various flow rates, such flow rate being chosen such that the higher flow rate is sufficient to transport the granular material located in the area of the extraction end (14) back towards the feeding end (13).

6. The method according to claim 1, wherein the granular material is delivered discontinuously.

7. A device to carry out a method for washing/cleaning granular material from slag as well as bottom/boiler ash from a thermal waste treatment as well as mineral residue and recycling material, comprising a cleaning channel (12) and at least one ultrasound generator (32, 33) subjecting the cleaning channel (12) and the process liquid therein and the granular material (16) therein to ultra sound, wherein the cleaning channel (12) extends upright or vertically in its longitudinal extension from an upper feeding end (13) to a lower extraction end (14), that ultrasound generators (32, 33) are located along the longitudinal extension of the cleaning channel (12), that the extraction end (14) is connected to a feed conduct (26) for process liquid, such that the delivered process liquid flows from the bottom to the top and that the feeding end (13) is connected to an overflow (28) in order to extract process liquid escaping from the cleaning channel (12).

8. The device according to claim 7, wherein the cross section of the cleaning channel is circular and that the ultrasound generators are located along the circumference of the flow channel.

9. The device according to claim 7, wherein the cross section of the cleaning channel (12) is essentially rectangular in shape and has at least two flat sides (31) extending along the flow direction and parallel to each other and that said ultrasound generators (32, 32) are located along the flat sides (31).

10. The device according to claim 7, wherein the sound emission surfaces of the ultrasound generators (32, 33) constitute the flat sides (31) of the cleaning channel (12) at least partially.

11. The device according to claim 9, wherein a flat side (31) is movable with the ultrasound generator (32) or the ultrasound generators (33) back and forth towards (34) the opposite flat side and that the narrow sides of the cleaning channel are connected upright to the flat sides by means of elastic seals (36) or are constituted by elastic seals.

12. The device according to claim 9, wherein a filter (28) the mesh width of which is smaller than the smallest diameter of the granular particles is provided upstream the feed conduct (26) for the process liquid.

13. The device according to claim 12, wherein the feed conduct (26) and the filter (28) are kept movable back and forth to the extraction end (34) in order to unblock or to close said extraction end (14) and that a collection device (18) for the granular material is provided downstream the extraction end (14).

14. The device according to claim 7, wherein the cleaning channel (12) is lockable upstream the extraction end (14) by means of a slide-valve (17) or a valve.

15. The device according to claim 7, wherein an inspection glass and/or a detection means (42/43) is provided in the sinking direction downstream the cleaning channel (12) and upstream the extraction end (14) and/or in the sinking direction upstream the cleaning channel (12) and downstream the feeding end (13) in order to detect the presence or the arrival of a granular grain in respectively at the extraction end (14) or in respectively at the feeding end (13).

Description

[0043] Hereinafter, the invention shall be explained by means of the schematic drawings. The drawings show:

[0044] FIG. 1 the view of a device according to the invention,

[0045] FIG. 2a the device during cleaning,

[0046] FIG. 2b the device during emptying,

[0047] FIG. 3 the top view of the cleaning channel,

[0048] FIG. 4a the view of the delivery device at the beginning of the cleaning and

[0049] FIG. 4b the view of the delivery device during cleaning.

[0050] The device for cleaning of slag granular material illustrated in the drawing comprises an upright cleaning chamber 11 wherein an upright and vertical cleaning channel 12 is provided. At its upper end, said cleaning channel 12 is limited by a feeding end 13 and at its lower end, by an extraction end 14. During cleaning operation, said cleaning channel 12 is filled with process liquid. Such process liquid can be water.

[0051] A delivery device 15 is provided upstream said feeding end through which the granular material to be cleaned can be delivered to the cleaning channel 12. Said granular material is constituted by a slag granular material from a specific grain fraction. Due to the specific weight of the particles which is higher than the weight of the process liquid and due to gravity, the various granular particles 16 descend from the feeding end 13 to the extraction end 14. Said extraction end 14 is closed by means of a slide-valve 17. A collection tank 18 is provided downstream said slide-valve 17. Following opening of said slide-valve 17, the granular particles 16 located thereon and the process liquid end up in the collection tank 18.

[0052] At its lower end, said collection tank 18 is also closed by means of a slide-valve 19. When opening the same, said granular material falls onto a filter 20 through which it is separated from said process liquid. The granular material is extracted. Such process liquid is collected in a collection tank 21 and delivered to a storage tank 23 for process liquid, using a pump 22.

[0053] Such storage tank 23 can be filled with fresh process liquid 24. From said storage tank 23, the process liquid is pumped by means of a pump 25 from the bottom, through a pipe 26, into the extraction end 14 and thereby into the cleaning channel 12. A flow of the process liquid towards the arrow 27 is generated against the sinking direction of the granular particles 16 in the cleaning channel 12. Such sinking velocity of the granular particles 16 in the cleaning channel 12 is controllable by means of the flow rate of said process liquid in the cleaning channel.

[0054] Due to the upwards flow of the cleaning liquid in the cleaning channel 12, the light substances filled in together with the granular material are separated from the descending granular material and transported upward to the feeding end 13. The delivery device 15 has an overflow 28 such that the light substances floating on the surface can be extracted together with the overflowing process liquid. Said overflow 28 empties out into a filter 29 through which the light substances are separated from said process liquid. The overflowing process liquid arrives in the storage tank 23 via a collection tank 30 downstream the filter 29.

[0055] In the exemplary embodiment illustrated in the drawing, said cleaning channel 12 is formed as a gap which is essentially rectangular. Such gap is limited by two opposite flat sides 31 and has a relatively small width which comes for example to only 10 mm to 30 mm, depending on the grain size of the granular material. Opposite plate-formed ultrasound generators 32, 33, the facing radiation surfaces are oriented towards the gap 12 are provided on the flat sides 31. In the top view according to FIG. 3, such gap is therefore limited by two ultrasound generators 32, 33 and by two narrow sides.

[0056] The plate-formed ultrasound generators 32, 33 can for example have a radiation surface of 565 mm×365 mm and extend over the entire width of said cleaning channel 12. Several ultrasound generators 32, 33 are stacked depending on the height of the cleaning channel 12. Three ultrasound generators 32, 33 are stacked in the exemplary embodiment shown.

[0057] For example, the power of said ultrasound generator 32, 33 can be 2,000 W. Such ultrasound generators are generally known in the art and require no further explanation. The power density which is relevant for cleaning the granular material depends in particular on the width of the gap of the cleaning channel 12. In order to achieve any change in the power density in the process liquid, it is possible to change the distance of the flat sides 31 and thus the radiation surfaces of the ultrasound generators 32, 33. To this end, the one or several ultrasound generator(s) 32 is/are located movably back and forth on the one side of the cleaning channel 12, transversally to the gap towards the arrow 34 on one traverse 35. The narrow sides can be constituted by an elastic side wall 36 or by an inflatable hose seal 37. A sealed cleaning channel 12 is constituted in any case, the width of which can be modified within a range of 10 mm to 30 mm, for example.

[0058] This enables adjustment of the power density in W/l to the granular material to be cleaned.

[0059] Such cleaning liquid is pumped via the pump 25 from the storage tank 23 through the pipe 26 into the cleaning channel 12. In more detail, this arrangement herein provides for the pipe to be located downstream the extraction end 14 of the cleaning channel and be fixed on a filter 38 extending over the pipe orifice. Thereby, descending particles are prevented from reaching and damaging the pump 25. The filter 38 is located hingeably downstream the extraction end 14.

[0060] During operation according to FIG. 2a, the granular material to be cleaned is delivered into the cleaning channel 12 by batches via the delivery device 15. The slide-valve 17 has been opened and the filter 38 with its pipe 26 is located downstream the extraction end 14. The pump 25 conducts the process liquid through the pipe 26 in the cleaning channel 12 such as to generate a flow in the direction of the arrow 27. The flow rate has been chosen such that the descending particles 16 are conducted back upwards towards the feeding end 13. Thus, the flow rate can be constant or, for example, intermittently pulsating, depending on the particle size of the granular material. Thereby, retention time of the particles 16 in the cleaning channel 12 is increased.

[0061] The pump 25 is thus set such that the process liquid rises and flows out via the overflow 28. Then, the light substances can be separated. Said overflowing process liquid is collected and conducted to the storage tank 23 such that it can circulate in a cycle. Only where a predetermined content of released impurities has been achieved, said process liquid can or must be treated or replaced.

[0062] Due to the upward oriented flow, the light substances are moved upwards in a first place. From there, they can be extracted via the overflow 28. To this end, water can transversely be delivered via a nozzle bar 39, thereby generating a surface flow towards the overflow 28 and quickly separating the light substances before they can get waterlogged and descend.

[0063] In order to prevent any extraction of the granular material to be cleaned via the overflow 28, a partition grid 40 is located in the flow area, the mesh width of which is smaller than the smallest particle to be cleaned. In detail, arrangement is provided such that said partition grid 40 is raised during filling of the delivery device 15 according to illustration of FIG. 4a. The granular material to be cleaned falls into the cleaning channel 12, together with the light substances.

[0064] During the filling process, process liquid already flows from the bottom to the top such that the lighter light substances are extracted preferably. The flow rate is chosen such that the light substances are carried upwards while the heavy granular material continues to descend.

[0065] Simultaneously, the partition grid 40 is subjected to air from its backside via a channel 41. Thereby, the partition grid 40 is cleaned from any potential attached light substances from the previous batch and simultaneously, the air flow also ensures more rapid transport of the floating light substances towards the overflow 28.

[0066] After removing the light substances, the partition grid 40 pivots into the horizontal position as illustrated in FIG. 4b, and closes the cleaning channel 12. As the mesh width of the partition grid 40 is smaller than the smallest grain of the granular material, it is now possible to raise the flow rate and thereby the upward flow of the process liquid such that individual granular materials rise upwards to the delivery end 13 of the cleaning channel 12 and descend again when the flow rate decreases, whereby achieving an optimum cleaning effect due to long retention time. The filling process and the first cleaning while the partition grid 40 being open can take approximately 5 to 20 and in particular 5 to 10 seconds. The following cleaning while the partition grid 40 being closed can take approximately 10 to 80 and in particular 20 to 60 seconds.

[0067] Following completion of the cleaning process, the flow is interrupted or decreased such that the cleaned particles descend and accumulate on the filter 38. The side-valve 17 downstream the cleaning channel 12 can be closed such that the process liquid relieved from the granular material remains in the cleaning channel 12. During extraction of the cleaned granular material and prior to filling in the following batch, it is also possible to already let process liquid flow into the cleaning channel 12 via the channel 39 and have it filled. Cycle time is thereby diminished, respectively optimised.

[0068] The filter 38 is hinged down and the side-valve 14 is opened such that the particles 16 fall into the collection tank 18 on the slide-valve 19 which is closed there. Thereupon, the slide-valve 14 is closed again. This is illustrated in FIG. 2b.

[0069] The slide-valve 19 is opened and the cleaned granular material, together with the process liquid, reach the filter 20, where it is extracted from. Said process liquid so co-extracted is pumped back into the storage tank 23 by means of the pump 22. This process liquid, too, is thereby recycled into the circuit.

[0070] In order to enable control or monitoring of the sedimentation behaviour of the delivered granular material, an inspection glass and/or detection means 42 enabling detection or viewing of the presence of a granular grain can be provided downstream the cleaning channel 12 and upstream the extraction end 14 or in the area of the extraction end. This makes it possible to detect when the first and the most rapidly descending granular grain has reached the extraction end 14. Then, it is possible to trigger the pump 25 such that such granular grain respectively the first incoming granular grains are carried back upwards.

[0071] Upon arrival of granular grains at the upper feeding end 13, pump output can be reduced such that sedimentation takes places again towards the extraction end 14. Upstream the cleaning channel 12 and downstream the partition grid 40 or in the area of the feeding end, an inspection glass and/or detection means 43 can therefore also be provided, allowing for detection or viewing of the presence of a granular grain. Then, it is possible to detect that the granular grains were carried back upwards. The pump output of the pump 25 is choked such that the granular grains descend back. The detection means 42, 43 are shown in the drawing only in FIG. 1.

[0072] This process is rerun until the predetermined retention time has been achieved. Detection of the granular grains at the extraction end and at feeding end can enable control of the pump output and thereby the flow rate of the process liquid in the cleaning channel 12 against the sinking direction such that all granular grains are predominantly located in the subjection zone between the ultrasound generators 32, 33 during the retention time.

[0073] Such a device allows for subjection on an individual basis to ultrasound of every particle of the DWIP-slag to be cleaned. There are no perturbing fixtures. Due to the gap-shaped cleaning channel, depth of penetration of the acoustic waves through the cleaning liquid until striking the particle is relatively low, such as to achieve a good cleaning effect. The number of machines deployed is small and the process liquid is recycled in a circuit. Thereby, it is possible to generate a processed slag meeting the critical values for sulphates and chlorides for the grading values Z1, Z1.1, or Z1.2 pursuant to “TR-LAGA”. Easy further use of the slag so cleaned is thus possible.