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Title:
APPARATUS FOR SEPARATING SOLID MATERIAL BY MEANS OF FLOTATION WITH A SOLID MEDIUM
Document Type and Number:
WIPO Patent Application WO/2016/193545
Kind Code:
A1
Abstract:
The invention relates to an apparatus for separating solid material (1a, 1b, 1c) by means of flotation taking place with a solid medium (5a, 5b), the apparatus comprising at least one vessel (4a, 4b) for the solid medium (5a, 5b); a gas supply arrangement (6a, 6b) to supply a gaseous medium to each vessel filled with the solid medium (5a, 5b) in order to adjust the density of the solid medium; a transport arrangement (3) for transporting solid material to the vessel and for transporting the material remaining on top of the solid medium onwards; and a removal conveyor arrangement (8a, 8b, 3b, 12a, 12b) for removing from the apparatus the fractions of the solid material which have sunk to the bottom of each vessel, whereby the removal conveyor arrangement comprises a rotating lifting drum (8a, 8b) which extends to the bottom of each vessel (4a, 4b) and above the solid medium (5a, 5b) in the vessel, and which is arranged transverse in relation to the direction of transport of the solid material, and through which the solid medium penetrates for lifting the fractions (1a, 1b) that have fallen on the bottom of the vessel from the bottom of the vessel to above the solid medium; and a removal conveyor (3b, 12a, 12b) extending inside the lifting drum to remove the fractions (1a, 1b) lifted up by the lifting drum to the outside of the lifting drum.

Inventors:
HÄMÄLÄINEN, Mikko (Sinkokatu 11, Rauma, 26100, FI)
BATISTA, Kristian (Sinkokatu 11, Rauma, 26100, FI)
Application Number:
FI2016/050386
Publication Date:
December 08, 2016
Filing Date:
June 01, 2016
Export Citation:
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Assignee:
BMH TECHNOLOGY OY (Sinkokatu 11, Rauma, 26100, FI)
International Classes:
B07B4/06; B07B7/01; B03B5/46
Foreign References:
IL54250A1981-09-13
US4035288A1977-07-12
Attorney, Agent or Firm:
KOLSTER OY AB (P.O.Box 148, Helsinki, Helsinki, 00121, FI)
Download PDF:
Claims:
Claims

1. An apparatus for separating solid material (1a, 1b, 1c) by means of flotation taking place with a solid medium (5a, 5b) in, for example, the classification of solid fuel fractions, the apparatus comprising

at least one vessel (4a, 4b) for the solid medium (5a, 5b); a gas supply arrangement (6a, 6b) for the vessel or each vessel (4a, 4b) to supply a gaseous medium to the vessel filled with the solid medium (5a, 5b) in order to adjust the density of the solid medium;

a transport arrangement (3) for transporting solid material (1a, 1b, 1c) to the vessel (4a, 4b) and for transporting the material (1b, 1c) remaining on top of the solid medium (5a, 5b) onwards out of the vessel or to a possible subsequent vessel; and

a removal conveyor arrangement (8a, 8b, 3b, 12a, 12b) for removing from the apparatus the fractions (1a, 1b) of the solid material which have sunk to the bottom of the vessel or each vessel (4a, 4b),

characterised in that the removal conveyor arrangement comprises

a rotating lifting drum (8a, 8b) which extends to the bottom of the vessel or each vessel (4a, 4b) and above the solid medium in the vessel, and which is arranged transverse in relation to the direction of transport of the solid material (1a, 1b, 1c), and through which the solid medium penetrates, and which has on its rim lifting means (11) for lifting fractions (1a, 1b) that have fallen on the bottom of the vessel from the bottom of the vessel to above the solid medium; and

a removal conveyor (3b, 12a, 12b) extending inside the lifting drum (8a, 8b) to remove the fractions (1a, 1b) lifted up by the lifting drum to the outside of the lifting drum.

2. An apparatus as claimed in claim 1, characterised in that the lifting drum (8a, 8b) is fitted with bearings above the medium (5a, 5b).

3. An apparatus as claimed in claim 2, characterised in that the lifting drum (8a, 8b) comprises an inner support rim structure (14), by means of which the inside of the lifting drum is fitted with at least one supporting bearing (9), the outer rim of the lifting drum being correspondingly fitted with at least one supporting bearing (9) against the outer rim.

4. An apparatus as claimed in any one of claims 1 -3, character i s e d in that the transport arrangement (3) comprises a chain conveyor extending across the apparatus and being equipped with scrapers (7).

5. An apparatus as claimed in any one of claims 1 -3, character i s e d in that removal conveyor comprises a sliding bottom (12a, 12b) arranged inside the lifting drum (8a, 8b) for the fractions (1a, 1b) dropping from the lifting drum, as well as and a chain conveyor (3b) arranged in cooperation with the sliding bottom and equipped with scrapers (7).

6. An apparatus as claimed in claim 5, characterised in that the transport arrangement (3) comprises a chain conveyor extending across the apparatus and equipped with scrapers (7), and having a lower supply portion (3a) moving on the surface of the vessel or vessels (4a, 4b), and an upper return portion (3b), which forms the chain conveyor that is in cooperation with the sliding bottom (12a, 12b) arranged inside the lifting drum (8a, 8b).

7. An apparatus as claimed in claim 6, characterised in that the scrapers (7) are formed asymmetric in relation to the centre line (C) of the conveyor (3a, 3b) so that it has, in relation to the centre line (C), a higher part (7a) and a lower part (7b), whereby when the scrapers (7) move on top of the sliding bottom (12a, 12b), the lower part (7b) carries ahead of it the solid material lifted out of the vessels (4a, 4b) and when travelling in the other direction the higher part (7a) sinks into the medium (5a, 5b) in the vessels (4a, 4b) or travels substantially near the surface and carries the removable solid material out of the vessels (4a, 4b).

8. An arrangement as claimed in any one of claims 1 - 3, c h a r- acterised in that the removal conveyor comprises an slanting slope arranged within the lifting drum (8a, 8b).

9. An apparatus as claimed in any one of the preceding claims, characterised in that the removal conveyor arrangement comprises an additional removal conveyor (13a, 13b, 16a, 16b) arranged outside of the lifting drum (8a, 8b) in order to remove the fractions that the removal conveyor (3b, 12a, 12b) delivered out of the apparatus.

10. An apparatus as claimed in claim 9, characterised in that the additional removal conveyor comprises a chain conveyor (13a, 13b) substantially transverse to the transport direction of the removal conveyor (3b, 12a, 12b) and equipped with scrapers (15), as well as a sliding bottom (16a, 16b) for the fractions (1a, 1b) coming from the removal conveyor and arranged in cooperation with the chain conveyor.

11. An apparatus as claimed in claim 9, characterised in that the additional removal conveyor comprises an slanting slope which is substantially transverse in relation to the transport direction of the removal conveyor.

12. An apparatus as claimed in any one of preceding claims, characterised in that the vessel or vessels (4a, 4b) are arranged at an oblique angle with respect to the horizontal plane.

13. An apparatus as claimed in any one of the preceding claims, characterised in that there are a plurality of vessels (4a, 4b) and they are so arranged that the subsequent vessel in the separation direction of the fractions is always lower with respect to the previous vessel.

14. An apparatus as claimed in any one of the previous claims, characterised in that the solid medium (5a, 5b) belongs to a group that comprises powdery or granular mediums, for example inert substances such as sand, salts, aluminium oxides or compounds thereof, as well as substances suitable for fuel, such as coal dust or sawdust.

15. An apparatus as claimed in any one of the preceding claims, characterised in that different vessels (4a, 4b) may have different kind of solid medium (5a, 5b) as relates to its grain size.

16. An apparatus as claimed in any one of the preceding claims, characterised in that different vessels (4a, 4b) have different kind of solid medium (5a, 5b).

17. An apparatus as claimed in any one of the preceding claims, characterised in that the gaseous medium is air or mixture that includes mainly air.

18. An apparatus as claimed in any one of the preceding claims, characterised in that the gaseous medium is supplied in different quantities to the solid medium (5a, 5b).

19. The use of the apparatus as claimed in claim 1 for material drying.

20. The use of the apparatus as claimed in claim 1 for material purification.

Description:
Apparatus for separating solid material by means of flotation with a solid medium

Background of the invention

[0001] The invention relates to an apparatus for separating solid material by means of flotation taking place with a solid medium in, for example, the classification of solid fuel fractions, the apparatus comprising at least one vessel for the solid medium; a gas supply arrangement for the vessel or each vessel to supply a gaseous medium to the vessel filled with the solid medium in order to adjust the density of the solid medium; a transport arrangement for transporting solid material to the vessel and for transporting the material remaining on top of the solid medium onwards out of the vessel or to a possible subsequent vessel; and a removal conveyor arrangement for removing from the apparatus the fractions of the solid material which have sunk to the bottom of the vessel or each vessel.

[0002] The majority of the world's energy production is still based on the steam process in which fuel is burned in a boiler to heat up water into steam, the energy contained therein is then converted into electricity through a turbine and a generator. In order to work, this process requires fuel the price and availability of which may vary a lot. The use of industrial, commercial or households waste as fuel provides a good source of fuel, but due to its heterogeneity also presents many challenges. From the point of view of burning, the waste contains problematic components such as stones, soil, metals, glasses, and other unburnable inerts, as well as substances like the PVC which, when burned, produce harmful compounds. The aim is to separate these unburnable or harmful or otherwise exploitable parts by various processes from among the material meant to be burned as well as technically and economically possible.

[0003] The refining of waste into good-quality fuel most often begins by bringing the waste into a suitable particle size from the point of view of further processing. These processing methods include crushing and screening of various kinds, among others. In the removal and sorting of non-magnetic particles, robots based on computer vision, separators based on the NIR technology, air separators, and flotation are used, among others. The drawback of robots and the NIR technology is their high cost and low capacity. Air separators are based on the weight difference between materials. The drawback of the method is that the shape and moisture of the pieces significantly affect the separation accuracy, so the method in question does not provide the required degree of purity. Liquid flotation methods are best suited to the separation of wood-containing substances, but their drawback is classification inaccuracy with other materials, the material meant as fuel becoming wet, and problems relating to the processing of the waste water that results as a by-product.

[0004] By separation based on flotation of materials by means of a solid medium the problems in the aforementioned methods can be avoided. A solid medium can in this case be made to behave like a liquid, but so that the density of the flotation medium may be adjusted within desired limits. The solutions making use of a solid medium typically use sand as the medium, through which air is typically blown. This results in that the buoyancy created by the selected medium on the pieces of the material flow changes, resulting in that pieces of a particular density remain on the surface of the medium whereas pieces with a higher density sink below the surface of the medium. The pieces remaining on the surface of the solid medium are transported onward or left to slide on a bevelled surface. In some solutions, separation values and fraction quantities may be predetermined.

[0005] From prior art, an apparatus is known which has one chamber and the medium has one density, whereby two different fractions are obtained.

[0006] In another apparatus, the densities of the fractions and their main compositions are predetermined. When sand is advantageously used as the medium, the problem arises of removing the particles that are heavier than the medium and have found their way to the bottom of the medium.

[0007] In yet another apparatus, a chain conveyor has been proposed to remove and transport the pieces. The chain links as well as the joints between the chain and scraper included in the chain conveyor and moving within the sand are in such a case prone to intense wear, as are the supporting wheels and slide blocks used to guide the chain.

Summary of the invention

[0008] The object of the invention is to remove the drawbacks described in the above by further developing the structure of the separating apparatus. This object is achieved by the apparatus according to the invention, which is mainly characterised in that the removal conveyor arrangement comprises a rotating lifting drum which extends to the bottom of the vessel or each vessel and above the solid medium in the vessel, which is transverse in rela- tion to the direction of transport of the solid material, and through which solid medium penetrates, and which has on its rim a lifting means for lifting fractions that have fallen on the bottom of the vessel from the bottom of the vessel to above the solid medium; and a removal conveyor extending inside the lifting drum to remove the fractions lifted up by the lifting drum to the outside of the lifting drum.

[0009] This solution allows, in the preferred embodiment of the invention, the bearings of the lifting drum to be fitted above the removal conveyor. This way, all the components of the apparatus, which are substantially susceptible to intense wear may be placed above the surface of a solid medium, typically sand, causing wear.

[0010] In such a case, the lifting drum advantageously comprises an inner support rim structure, by means of which the inside of the lifting drum is fitted with at least one supporting bearing, the outer rim of the lifting drum being correspondingly fitted with at least one supporting bearing against the outer rim.

[0011] An advantageous combination of the parts of the apparatus may be one where the removal conveyor comprises a sliding bottom arranged inside the lifting drum for the fractions dropping from the lifting drum, and a chain conveyor arranged in cooperation with the sliding bottom and equipped with scrapers, whereby the transport system comprises a chain conveyor, extending across the apparatus and being equipped with scrapers, and which has a lower supply portion moving on the surface of the vessel or vessels, and an upper return portion which forms said chain conveyor arranged inside the lifting drum and being in cooperation with said sliding bottom. This way, the conveyor used for transporting solid material may also be used in the removal of the separated fractions.

[0012] Other preferred embodiments of the invention are disclosed in the dependent claims.

List of figures

[0013] The invention is now described in closer detail by means of one preferred embodiment with reference to the accompanying drawings, in which

[0014] Figure 1 shows an apparatus according to the invention as a longitudinal cross section; [0015] Figure 2 shows the apparatus of Figure 1 cut along line B - B of Figure 1 ,

[0016] Figure 3 shows the scraper arrangement of Figure 1 in more detail, and

[0017] Figure 4 shows the arrangement of Figure 3 as a section along line A - A of Figure 3.

Detailed description of the invention

[0018] With reference to the figures, the apparatus according to the invention for separating solid material by means of flotation with a solid medium, in particular to classify solid fuel fractions 1 a, 1 b, 1 c now disclosed, comprises two successive vessels 4a, 4b that contain a solid medium 5a, 5b. The medium 5a, 5b may in principle be any substance in powder or grain form, for example inert substances such as sand, salts, aluminium oxide or compounds thereof, and also substances suitable for fuel, such as coal dust or sawdust. For each vessel 4a, 4b, there is a gas supply arrangement, of which nozzles 6a, 6b are shown, to supply a gaseous medium, advantageously air, into the vessels 4a, 4b filled with a solid medium 5a, 5b to adjust the density of the solid medium 5a, 5b. In order to transport fractions 1 a, 1 b, 1 c to the vessels 4a, 4b, and to transport fractions 1 b, 1 c that remain on the solid medium 5a, 5b onwards to the next vessel 4b and out of the apparatus, a transport conveyor 3 has been arranged. In order to remove the fractions 1 a, 1 b that have sunk to the bottom of the vessel 4a, 4b, a removal conveyor arrangement 8a, 8b, 3b, 12a, 12b, 13a, 13b has been arranged. To supply fractions 1 a, 1 b, 1 c to the transport conveyor, a supply channel 2 has been arranged.

[0019] The removal conveyor arrangement comprises two rotating lifting drums 8a, 8b, extending thus to the bottom of each vessel 4a, 4b and above the solid medium 5a, 5b in the vessels 4a, 4b and above the transport conveyor 3, arranged transverse in relation to the direction of transport of the solid material, and through which the solid medium 5a, 5b penetrates, and which have on their rims lifting means 1 1 for lifting fractions 1 a, 1 b that have fallen on the bottom of the vessels from the bottom of the vessel to above the solid medium 5a, 5b. Each lifting drum 8a, 8b at the same time substantially extends on the entire length of the vessel 4a, 4b in question. The penetrability of the lifting drums 8a, 8b may be implemented by means of openings 10a or the gap-like structure 10b of the drum structure. In Figure 1 , the left sides of the lifting drums 8a, 8b are shown as structures having gaps, and the right sides as structures having openings. Both lifting drums 8a, 8b may obviously be entirely of either structure. The lifting means 1 1 may be formed in a similar manner as penetrating structures.

[0020] The removal conveyor arrangement additionally comprises removal conveyors 3b, 12a, 12b extending inside the lifting drums 8a, 8b to remove the fractions 1 a, 1 b lifted up by the lifting drums 8a, 8b to the outside of the lifting drums 8a, 8b.

[0021] The lifting drums 8a, 8b are fitted with bearings above the medium 5a, 5b, and the imaginary rotation axes of the lifting drums 8a, 8b pass substantially parallel to the central longitudinal axis of the apparatus, and close to this longitudinal axis. For rotation, the lifting drums 8a, 8b comprise inner support rim structures 14, by means of which the inside of the lifting drum 8a, 8b is fitted with at least one supporting bearing 9, the outer rim of the lifting drum 8a, 8b being correspondingly fitted with at least one similar supporting bearing 9 against the outer rim.

[0022] The removal conveyors 3b, 12a, 12b comprise sliding bottoms 12a, 12b arranged inside the lifting drum 8a, 8b for the fractions 1 a, 1 b dropping from the lifting drums 8a, 8b, and a chain conveyor 3b equipped with scrapers 7 and arranged to cooperate with the sliding bottoms 12a, 12b. Now that the transport conveyor 3 comprises a chain conveyor extending across the apparatus and equipped with scrapers 7, and having a lower supply portion 3a moving on the surface of the vessels 4a, 4b, and an upper return portion 3b, this upper return portions forms said chain conveyor 3b that is in cooperation with said sliding bottoms 12a, 12b arranged inside the lifting drum 8a, 8b. It should be noted that the chain conveyor may be replaced with another conveyor if this is technically possible and advantageous.

[0023] Figures 3 and 4 illustrate an advantageous implementation of the scrapers 7, whereby the scrapers 7 are formed asymmetric in relation to the centre line C of the conveyor 3a, 3b so that it has, in relation to the centre line C, a higher part 7a and a lower part 7b, whereby when the scrapers 7 move on top of the sliding bottom 12a, 12b, the lower part 7b carries ahead of it the solid material lifted out of the vessels 4a, 4b and when travelling in the other direction the higher part 7a sinks into the medium 5a, 5b in the vessels 4a, 4b or travels substantially near the surface and carries the removable solid material out of the vessels 4a, 4b. [0024] The removal conveyor arrangement also comprises additional removal conveyors arranged outside the lifting drums in order to remove the fractions 1 a, 1 b that the removal conveyors 3b, 12a, 12b delivered out of the apparatus. These additional removal conveyors here comprise chain conveyors 13a, 13b substantially transverse to the transport direction of the removal conveyor 3b, 12a, 12b and equipped with scrapers 15, as well as sliding bottoms 16a, 16b for the fractions 1 a, 1 b coming from the removal conveyor and arranged in cooperation with the chain conveyors.

[0025] In an alternative implementation it is possible that the removal conveyors 3a, 12a, 12b are replaced with slanting slopes arranged inside the lifting drums 8a, 8b. Correspondingly, the additional removal conveyors 13a, 13b may be replaced with slanting slopes substantially transverse in relation to their transport direction. In such a case, these conveyors may possibly both be combined into one removal conveyor.

[0026] In an alternative implementation, the vessels 4a, 4b may be arranged at an oblique angle with respect to the horizontal plane and/or the vessels 4a, 4b are arranged so that in the separation direction of the fractions 1 a, 1 b, 1 c, the subsequent vessel is always lower compared to the previous vessel. In such a case, it may also be possible that the transport conveyor portion 3a is not needed, but the transport arrangement is established by this inclination in the forward direction of the apparatus.

[0027] Different vessels 4a, 4b may have different kind of solid medium as relates to its grain size, and/or different solid medium. The number of the vessels is not limited, either. At times, one vessel may be enough, and there may be more vessels than the now disclosed two vessels 4a, 4b.

[0028] The operation of the apparatus may be described in brief as follows:

[0029] Fuel fractions 1 a - 1 c are supplied through a supply channel 2 to a conveyor 3, which carries the fractions to a first vessel 4a. The density of a solid medium 5a in this vessel 4a is adjusted by supplying a gaseous medium to the medium 5a, advantageously air, through a nozzle 6a. Different amounts of this gaseous medium may be supplied to the medium 5a, 5b. The supplied gas changes the density of the medium 5a so that only the densest part of the material flow, that is, fractions 1 a, sink to the bottom of the vessel 4a while the fractions 1 b, 1 c that have a lower density move into the subsequent vessel 4b with the aid of scrapers 7 in the supply portion 3a of the con- veyor 3. A lifting drum 8a picks up the densest fractions 1 a that have found their way to the bottom of the vessel 4a. Lifting elements 1 1 of the lifting drum 8a lift up the fractions 1 a which are denser than the medium 5a and have found their way to the bottom of the medium 5a, and move them to be transported by the return portion 3b of the conveyor 3. The removed fractions 1 a slide along the sliding bottom 12a of the return portion 3b, acting as the removal conveyor, to a transverse additional removal conveyor 13a. The same event is repeated identically at the subsequent vessel 4b so that the next densest fractions 1 b stay in the vessel 4b, and only the fractions 1 c that have the smallest density remain, which are eventually removed from the apparatus by means of the supply portion 3a of the conveyor 3.

[0030] The above description of the invention is only intended to illustrate the basic idea of the invention. A person skilled in the art may thus vary its details within the scope of the attached claims. It should be noted that, in addition to material separation, the apparatus according to the invention may also be used for material drying and/or purifying, although this is not separately explained.