APPARATUS AND METHOD FOR THE TREATMENT OF A SUBSTRATE WITH A MULTIPLICITY OF SOLID PARTICLES

Abstract

An apparatus for use in the treatment of substrates with a solid particulate material, said apparatus comprising: (a) a housing having mounted therein a rotatably mounted drum (8) having an inner surface and an end wall; and (b) access means for introducing said substrates into said drum, wherein said drum comprises storage means (2) for storage of said solid particulate material and a plurality of flow paths to facilitate flow of said solid particulate material between said storage means and the interior of said drum (8), characterised in that: said drum (8) comprises a dispensing flow path (5) to facilitate flow of said solid particulate material from said storage means (2) to the interior of said drum (8), and a collecting flow path (6) to facilitate flow of said particulate material from the interior of said drum (8) to said storage means (2), wherein said dispensing flow path (5) and said collecting flow path (6) are different flow paths.

Claims

1. An apparatus for use in the treatment of substrates with a solid particulate material, said apparatus comprising: (a) a housing having mounted therein a rotatably mounted drum having an inner surface and an end wall; and (b) access means for introducing said substrates into said drum, wherein said drum comprises storage means for storage of said solid particulate material and a plurality of flow paths to facilitate flow of said solid particulate material between said storage means and the interior of said drum, characterised in that: said drum comprises a dispensing flow path to facilitate flow of said solid particulate material from said storage means to the interior of said drum, and a collecting flow path to facilitate flow of said particulate material from the interior of said drum to said storage means, wherein said dispensing flow path and said collecting flow path are different flow paths.

2. An apparatus according to claim 1 wherein said flow of said solid particulate material from the storage means towards the interior of the drum is facilitated by the rotation of said drum in a dispensing direction and/or the flow of said solid particulate material from the interior of the drum towards the storage means is facilitated by the rotation of said drum in a collecting direction, wherein rotation in the dispensing direction is in the opposite rotational direction to rotation in the collecting direction.

3. An apparatus according to claim 2 wherein the dispensing flow path and/or the storage means are configured such that it takes at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 rotations in the dispensing direction to begin to release the solid particulate material into the interior of said drum.

4. An apparatus according to any preceding claim wherein the apparatus does not comprise a further storage means which is not attached to or integral with the drum, and/or wherein the apparatus does not comprise a pump for circulating said solid particulate material between the storage means and the interior of the drum.

5. An apparatus according to any preceding claim wherein the apparatus does not comprise a pump for circulating said solid particulate material.

6. An apparatus according to any preceding claim wherein the collecting flow path comprises a collecting aperture and the drum is configured to bias solid particulate material present inside the drum towards said collecting aperture during rotation of the drum in the collecting direction.

7. An apparatus according to any of preceding claim wherein the dispensing flow path comprises a dispensing aperture and the drum is configured to bias solid particulate material present inside the storage means and/or dispensing flow path towards a dispensing aperture during rotation of the drum in a dispensing direction.

8. An apparatus according to any preceding claim wherein said drum has at least one elongate protrusion located on said inner surface of said drum wherein the elongate protrusion extends in a direction away from said end wall, preferably wherein said drum comprises two, three, four, five or six elongate protrusions.

9. An apparatus according to any preceding claim wherein said drum has at least one elongate protrusion located on said inner surface of said drum wherein the elongate protrusion extends in a direction away from said end wall and preferably extends from said end wall, wherein said elongate protrusion has an end proximal to the end wall and an end distal to the end wall.

10. An apparatus according to claim 9 wherein a collecting flow path comprises a collecting aperture which is located in an elongate protrusion at its proximal end.

11. An apparatus according to claim 9 or 10 wherein a dispensing flow path comprises a dispensing aperture which is located in an elongate protrusion at its distal end or closer to its distal end than its proximal end, or from at least about half way along the elongate protrusion from the proximal end to the distal end thereof, or wherein an elongate protrusion has a plurality of dispensing apertures spaced along the length of the elongate protrusion from its proximal end to its distal end.

12. An apparatus according to any of claims 9 to 11 wherein said dispensing flow path is located at least in part in an elongate protrusion.

13. An apparatus according to any of claims 9 to 12 wherein said drum and/or said at least one elongate protrusion are configured to bias solid particulate material present inside the drum towards the collecting flow path, and particularly towards the end wall, during rotation of the drum in a collecting direction.

14. An apparatus according to 13 wherein said at least one elongate protrusion is curvilinear and configured to bias said solid particulate material towards a collecting aperture located in the elongate protrusion at its proximal end during rotation of the drum in a collecting direction.

15. An apparatus according to claim 13 wherein said at least one elongate protrusion is rectilinear.

16. An apparatus according to any of claims 9 to 15 wherein the axis of said drum is substantially horizontal.

17. An apparatus according to any of claims 9 to 15 which is configured such that for at least a part of said treatment the drum is tilted such that its axis defines an angle A to the horizontal plane which is greater than 0 and less than about 10 and such that the drum is inclined in a downwards direction from the front of the drum to the end wall of the drum.

18. An apparatus according to any of claims 9 to 17 wherein an elongate protrusion comprises one or more collecting aperture(s) disposed in a first side thereof at one or more position(s) from the proximal end to the distal end thereof, wherein the first side of the elongate protrusion is the leading side of the elongate protrusion during rotation of the drum in a collecting direction, and wherein the collecting aperture(s) is/are in fluid communication with the collecting flow path via a chain of open compartments which are located in the base or on the underside of the elongate protrusion and which are configured to bias solid particulate material towards the collecting flow path and storage means during rotation of the drum.

19. An apparatus according to any of claims 9 to 18 wherein said storage means and/or said at least one elongate protrusion are configured to bias solid particulate material present inside the storage means and/or dispensing flow path towards a dispensing aperture located in said at least one elongate protrusion at its distal end or closer to its distal end than its proximal end or from at least about half way along the elongate protrusion from the proximal end to the distal end thereof during rotation of the drum in a dispensing direction.

20. An apparatus according to any of claims 9 to 19 wherein said dispensing flow path comprises an Archimedian screw arrangement located in the elongate protrusion.

21. An apparatus according claim 20 wherein the cross-section of said Archimedian screw is circular, or tri-lobal or other multi-lobal configuration.

22. An apparatus according to any of claims 9 to 19 wherein said dispensing flow path comprises a chain of open compartments located in the elongate protrusion, wherein said open compartments are formed by a first series of inclined vanes substantially parallel to each other and a second series of inclined vanes substantially parallel to each other, wherein said first and second series are disposed along at least part of the length of the interior of the elongate protrusion, wherein said first series of vanes are disposed in a facing arrangement to said second series of vanes, wherein said first series of vanes are not parallel to said second series of vanes, and wherein the compartments and vanes are configured to bias solid particulate material present inside the storage means and/or dispensing flow path towards a dispensing aperture located in said at least one elongate protrusion at its distal end or closer to its distal end than its proximal end or at least about half way along the elongate protrusion from the proximal end to the distal end thereof during rotation of the drum in a dispensing direction.

23. An apparatus according to any of claims 9 to 19 wherein said dispensing flow path comprises opposing and offset saw-tooth surfaces configured to bias solid particulate material present inside the storage means and/or dispensing flow path towards a dispensing aperture located in said at least one elongate protrusion at its distal end or closer to its distal end than its proximal end or at least about half way along the elongate protrusion from the proximal end to the distal end thereof during rotation of the drum in a dispensing direction.

24. An apparatus according to any of claims 9 to 23 wherein the storage means is or comprises at least one cavity located in an elongate protrusion.

25. An apparatus according to any of claims 8 to 23 wherein the storage means and the elongate protrusions can be assembled inside the drum, and/or are able to be retrofitted to an existing drum, and/or are removable and replaceable such that the solid particulate material contained therein may be replaced with fresh solid particulate material.

26. An apparatus according to any preceding claim wherein the inner surface of the drum is textured or contoured with guiding elements affixed thereto or formed integrally therewith to bias solid particulate material towards the end-wall of the drum during rotation of the drum in a collecting direction.

27. An apparatus according to claim 26 wherein said drum comprises a plurality of elongate protrusions located on said inner surface of said drum wherein the elongate protrusion extends in a direction away from said end wall and preferably extends from said end wall, wherein said elongate protrusion has an end proximal to the end wall and an end distal to the end wall, and wherein said guiding element comprises one or more ribs and/or one of more grooves which are disposed on or in the inner surface of the drum between adjacent elongate protrusions such that said rib(s) and/or groove(s) are angled in a manner which directs solid particulate material away from a first elongate protrusion and the front of the drum and towards the adjacent elongate protrusion and the end-wall of the drum during rotation of the drum in a colleting direction.

28. An apparatus according to claim 27 wherein the guiding element is a rib having a profile configured to retain solid particulate material during the biasing thereof towards the end-wall of the drum, preferably wherein the edge of the rib which is the leading edge during rotation of the drum in a collecting direction comprises a collecting groove which runs at least partially along the length of the rib.

29. An apparatus according to claim 26 wherein the guiding element is a perforated diverting rib disposed on the inner surface of the drum such that it extends in a direction away from the end-wall of the drum and towards the front of the drum, wherein the perforated diverting rib has a first edge which is the leading edge during rotation of the drum in a collecting direction and a second edge which is the trailing edge during rotation of the drum in a collecting direction, wherein each of the first and second edges has one or more apertures therein, and wherein the perforated diverting rib comprises a plurality of angled channels which connect the aperture(s) on the first edge with the aperture(s) on the second edge, and wherein the exit point from an angled channel at the second edge of the rib is closer to the end-wall of the drum than the entry point into that angled channel at the first edge of the rib, thereby allowing solid particulate material to flow through the perforated diverting rib so that during rotation of the drum in a collecting direction the solid particulate material is biased towards the end-wall of the drum.

30. An apparatus according to claim 29 wherein said drum comprises a plurality of elongate protrusions located on said inner surface of said drum wherein the elongate protrusion extends in a direction away from said end wall and preferably extends from said end wall, wherein said elongate protrusion has an end proximal to the end wall and an end distal to the end wall, and wherein one or more perforating diverting rib(s) are disposed on the inner surface of the drum between adjacent elongate protrusions.

31. An apparatus according to any preceding claim wherein the storage means comprises multiple compartments, for instance, 2, 3, 4, 5 or 6 compartments, particularly wherein said multiple compartments are arranged so as to retain balance of the drum during rotation.

32. An apparatus according to any of claims 1 to 31 wherein the storage means is or comprises at least one cavity located in the end wall of the drum.

33. An apparatus according to any preceding claim wherein the storage means comprises multiple compartments located in the end wall of the drum, wherein each of the compartments is defined by a cavity bound by a first wall and a second wall which each extend outwards from the rotational axis of the drum towards and preferably to the inner wall of the drum, preferably wherein each compartment is associated with a single dispensing flow path and a single collecting flow path.

34. An apparatus according to claim 33 wherein each compartment is in fluid communication with its adjacent compartment or compartments such that solid particulate material, as well as any liquid medium, is able to pass from one compartment directly into an adjacent compartment during rotation of the drum.

35. An apparatus according to claim 34 wherein fluid communication between adjacent compartments is effected by a communicating aperture in the wall between adjacent compartments, preferably wherein a communicating aperture exhibits a smallest dimension which is at least 4 times greater than the longest dimension of the solid particulate material, and preferably wherein the largest dimension of the communicating aperture is no greater than 50% of the longest dimension of a wall between adjacent compartments, and preferably wherein said communicating aperture is located in a wall between adjacent compartments at a point that is closer to the mid-point of said wall between adjacent compartments than to either the rotational axis of the drum or the inner wall of the drum.

36. An apparatus according to any of claims 1 to 32 wherein the storage means is or comprises at least one spiral or helical pathway located in the end wall of the drum.

37. An apparatus according to any of claim 1 to 32 or 36 wherein the storage means is or comprises a toroidal cavity located at the juncture of said inner surface and said end wall or wherein the storage means is or comprises a cavity having a shape defined by a toroidal segment located at the juncture of said inner surface and said end wall.

38. An apparatus according to any of claim 1 to 32, 36 or 37 wherein the storage means is or comprises at least one cavity located in said inner wall of the drum.

39. An apparatus according to any preceding claim wherein the storage means further comprises one or more perforations which have dimensions smaller than the dimensions of the solid particulate material so as to permit passage of fluids through said perforations into and out of the storage means, particularly from the interior of said drum, but to prevent egress of said solid particulate material through said perforations.

40. An apparatus according to any preceding claim wherein the storage means comprises multiple parts, preferably 2, 3 or 4 parts, which can be assembled inside the drum and/or which is able to be retrofitted to an existing drum.

41. An apparatus according to any preceding claim wherein said collecting flow path comprises a valve, preferably a one-way flap valve, to prevent egress of said solid particulate material from said storage means to the interior of said drum via said collecting flow path.

42. An apparatus according to any preceding claim wherein at least a portion of the collecting flow path is juxtaposed with at least a portion of the dispensing flow path, wherein said juxtaposed potions are separated by a deflector wall which helps to prevent egress of said solid particulate material from said storage means to the interior of said drum via said collecting flow path and/or which assists in biasing the particles towards the dispensing path.

43. An apparatus according to any preceding claim wherein the dispensing flow path is configured such that it dispenses solid particulate material from a dispensing aperture therein when the dispensing aperture is above the horizontal plane bisecting the axis of drum rotation.

44. An apparatus according to any preceding claim wherein the dimensions of said dispensing and collecting flow paths are such that they have no internal dimension which is less than at least 2 times, more preferably at least 3 times, the longest dimension of the solid particulate material.

45. An apparatus according to any preceding claim wherein the inner surface of the rotatably mounted drum is configured to bias solid particle material towards the end wall of the drum, preferably wherein said inner surface defines a frusto-conical surface such that the inner surface of the drum is inclined in a downwards direction from the front of the drum to the end wall of the drum, preferably wherein the collecting flow path comprises a collecting aperture which is located in an elongate protrusion at its proximal end.

46. An apparatus according to claim 45 wherein the inner surface of the drum is configured to define at least one collecting channel in the inner surface at the juncture of the inner surface and the end-wall of the drum, wherein the collecting channel extends along the juncture of the inner surface and the end-wall of the drum to the collecting aperture, and is thus configured to bias solid particulate material towards the collecting aperture during rotation of the drum in a collecting direction.

47. An apparatus according to any preceding claim wherein the inner surface of said drum comprises perforations which have dimensions smaller than the dimensions of the solid particulate material so as to permit passage of fluids into and out of said drum but to prevent egress of said solid particulate material.

48. An apparatus according to claim 47 wherein said housing is a tub which surrounds said drum, preferably wherein said tub and said drum are substantially concentric, preferably wherein the walls of said tub are unperforated but having disposed therein one or more inlets and/or one or more outlets suitable for passage of a liquid medium and/or one or more treatment agents into and out of the tub.

49. An apparatus according to any preceding claim further comprising a seal between the access means and the tub.

50. An apparatus according to any preceding claim wherein said drum has an opening at the opposite end of the drum to the end wall through which said substrates are introduced into said drum.

51. An apparatus according to any preceding claim wherein said treatment of substrates with solid particulate material is in the presence of a liquid medium and/or one of more treatment formulation(s).

52. An apparatus according to any preceding claim which comprises said solid particulate material.

53. An apparatus according to any preceding claim wherein the particles of the solid particulate material have (i) an average mass of from about 1 mg to about 1000 mg; and/or (ii) an average volume in the range of from about 5 to about 500 mm.sup.3; and/or (iii) an average surface area of from 10 mm.sup.2 to 500 mm.sup.2 per particle; and/or (iv) an average particle size of from 1 mm to 20 mm, preferably from 5 mm to 10 mm; and/or (v) and average density of at least about 1 g/cm.sup.3 or at least about 1.4 g/cm.sup.3.

54. An apparatus according to any preceding claim wherein the particles of the solid particulate comprise a polymer, preferably wherein the polymer is or comprises a polyalkylene, a polyamide, a polyester or a polyurethane, preferably a polyalkylene, polyester or polyamide, preferably a polyamide selected from nylon 6 or nylon 6,6 or a polyalkylene selected from polypropylene, and preferably a polyamide or a polyamide selected from nylon 6 or nylon 6,6.

55. An apparatus according to any preceding claim wherein the particles of the solid particulate are selected from metal, alloy, ceramic and glass particles.

56. An apparatus according to any preceding claim wherein the particles of the solid particulate material are spheroidal and/or ellipsoidal.

57. An apparatus according to any preceding claim wherein the rotatable drum is cylindrical.

58. A method of constructing an apparatus as defined in any of claims 1 to 57 which is suitable for use in the treatment of substrates using a solid particulate material, the method comprising retrofitting a starting apparatus which is not suitable for use in the treatment of substrates using a solid particulate material and which comprises a housing having mounted therein a rotatably mounted drum having an inner surface and an end wall and which further comprises access means for introducing said substrates into said drum, wherein said retrofitting comprises the steps of: (i) providing solid particulate material, providing one or more storage means for storage of solid particulate material, providing a dispensing flow path to facilitate flow of said solid particulate material from said storage means to the interior of said drum, and providing a collecting flow path to facilitate flow of said particulate material from the interior of said drum to said storage means, wherein said dispensing flow path and said collecting flow path are different flow paths; and (ii) disposing said storage means and said dispensing and collecting flow paths on one or more interior surface(s) of the drum, and preferably wherein said retrofitting comprises the steps of: (i) providing one or more storage means, one or more elongate protrusions, and solid particulate material; and (ii) affixing said storage means and said elongate protrusion(s) to one or more interior surface(s) of the drum so that said drum comprises a dispensing flow path to facilitate flow of said solid particulate material from said storage means to the interior of said drum, and a collecting flow path to facilitate flow of said particulate material from the interior of said drum to said storage means, wherein said dispensing flow path and said collecting flow path are different flow paths, wherein said collecting flow path comprises a collecting aperture which is located in an elongate protrusion at its proximal end, and wherein said dispensing flow path comprises a dispensing aperture which is located in an elongate protrusion at its distal end or closer to its distal end than its proximal end.

59. A kit for converting an apparatus which is not suitable for use in the treatment of substrates using a solid particulate material into an apparatus as defined in any of claims 1 to 57 which is suitable for use in the treatment of substrates using a solid particulate material, wherein the apparatus comprises a housing having mounted therein a rotatably mounted drum having an inner surface and an end wall and which further comprises access means for introducing said substrates into said drum, wherein said kit comprises solid particulate material, storage means for storage of said solid particulate material, a dispensing flow path to facilitate flow of said solid particulate material from said storage means to the interior of said drum, and a collecting flow path to facilitate flow of said particulate material from the interior of said drum to said storage means, wherein said dispensing flow path and said collecting flow path are different flow paths, and wherein said kit is adapted to allow disposing said storage means and said dispensing and collecting flow paths on one or more interior surface(s) of the drum, and preferably wherein said kit comprises storage means for storage of said solid particulate material, one or more elongate protrusions, and solid particulate material, wherein said kit is adapted to allow affixing of said storage means and said elongate protrusion(s) to one or more interior surface(s) of the drum so that said drum comprises a dispensing flow path to facilitate flow of said solid particulate material from said storage means to the interior of said drum, and a collecting flow path to facilitate flow of said particulate material from the interior of said drum to said storage means, wherein said dispensing flow path and said collecting flow path are different flow paths, wherein said collecting flow path comprises a collecting aperture which is located in an elongate protrusion at its proximal end, and wherein said dispensing flow path comprises a dispensing aperture which is located in an elongate protrusion at its distal end or closer to its distal end than its proximal end.

60. A kit comprising solid particulate material, storage means for storage of said solid particulate material, a dispensing flow path to facilitate flow of said solid particulate material from said storage means to the interior of said drum, and a collecting flow path to facilitate flow of said particulate material from the interior of said drum to said storage means, wherein said dispensing flow path and said collecting flow path are different flow paths, and wherein said kit is adapted to allow disposing said storage means and said dispensing and collecting flow paths on one or more interior surface(s) of the drum, and as defined in claim 59, wherein the kit is a replacement for said solid particulate material, said storage means, said dispensing flow path and said collecting flow path already disposed on one or more interior surface(s) of the drum of an apparatus.

61. A method of treating a substrate, the method comprising agitating the substrate in an apparatus according to any of claims 1 to 57 with solid particulate material.

62. A method according to claim 61 wherein the solid particulate material is re-used in further treatment procedures according to the method.

63. A method according to claim 61 or 62 wherein the method is a method for treating multiple batches, wherein a batch comprises at least one substrate, the method comprising agitating a first batch with solid particulate material, wherein said method further comprises the steps of: (a) collecting said solid particulate material in the storage means; (b) agitating a second batch comprising at least one substrate with solid particulate material collected from step (a); and (c) optionally repeating steps (a) and (b) for subsequent batch(es) comprising at least one substrate.

64. A method according to any of claims 61 to 63 wherein the method comprises agitating the substrate with solid particulate material and a liquid medium, preferably wherein the liquid medium is aqueous.

65. A method according to any of claims 61 to 64 wherein the method comprises agitating the substrate with said solid particulate material and a treatment formulation.

66. A method according to any of claims 61 to 65 wherein the substrate is or comprises a textile.

67. A method according to claim 66 wherein the treating of said substrate is cleaning, coloration, bleaching, abrading or ageing, or other textile or garment finishing process.

68. A method according to claim 67 for cleaning a substrate wherein the substrate is a soiled substrate.

69. A method according to any of claims 61 to 65 wherein the substrate is or comprises an animal skin substrate.

70. A method according to claim 69 wherein the treating of an animal skin substrate is a tannery process.

Description

[0151] The invention is further illustrated with reference to the following figures.

[0152] FIG. 1 illustrates a section of the apparatus showing the end wall (1) of the drum having disposed therein storage means (2). A first elongate protrusion (3a) comprises a dispensing aperture (4) at its distal end and a dispensing flow path (5) which is configured as an Archimedean screw.

[0153] FIG. 2 illustrates a larger section of the drum showing the first elongate protrusion and a second elongate protrusion 3b.

[0154] FIG. 3 shows the region of the apparatus where elongate protrusion (3a) meets the end wall (1) of the drum in which is disposed the storage means. Solid particulate material enters the storage means via the collecting flow path (6) and collecting aperture (7). A portion of deflector wall (8) separates the collecting flow path (6) from the dispensing flow path (5).

[0155] FIG. 4 shows in more detail the arrangement of the dispensing flow path (5), collecting flow path (6) and deflector wall (8) from the opposite side, relative to FIG. 3. A portion of elongate protrusion (3a) is also shown. One-way flap-valve (9) prevents egress of solid particulate material from the storage means into the interior of the drum via the collecting pathway.

[0156] FIG. 5 shows collecting aperture (7) in the proximal end of elongate protrusion (3a) at the end wall (1) of the drum.

[0157] FIG. 6 shows a larger perspective view of the end wall (1) of a drum comprising storage means in three sections (1a, 1b, and 1c) allowing it to be retrofitted to existing drums. The figure also shows elongate protrusions (3a, 3b and 3c).

[0158] FIG. 7 shows the end wall (1) of a drum comprising storage means therein, and elongate protrusions (3a, 3b and 3c) disposed on the cylindrical inner surface (10) of the drum.

[0159] FIG. 8 shows certain elements of a rotatable drum (12) having an end wall (1) and a cylindrical inner surface (10), and located in a housing (11), wherein the interior of the drum is accessed by access means (13) and wherein the drum is connected to drive shaft (14) from a drive means (not shown) to effect rotation of the drum.

[0160] FIG. 9 shows the arrangement of FIG. 8 wherein a storage means (2) is disposed in, or retrofitted onto, the existing end wall (1) of the drum.

[0161] FIGS. 10 and 11 show an arrangement with a plurality of storage means (2a, 2b) and a plurality of elongate protrusions (3a, 3b).

[0162] FIGS. 12, 13 and 14 show an elongate protrusion (3d), having the paternoster configuration described herein, wherein the dispensing flow path comprises a chain of open compartments (15a, b) formed by a first series of inclined, substantially parallel vanes (16a, b) and a second series of inclined, substantially parallel vanes (17a, b). FIG. 14 shows the elongate protrusion and dispensing flow path in dissembled form.

[0163] FIG. 15 shows a multi-compartment storage means located in the end-wall of the drum as hereinbefore described, comprising compartments 18a, 18b and 18c. Each compartment is in fluid communication with an adjacent compartment via communicating apertures 19a, 19b and 19c. Each compartment is associated with a single lifter 20a and 20c (lifter 20b not shown), and each compartment is associated with a single dispensing flow path (5a) and a single collecting flow path (6a) (shown only for compartment 18a.

[0164] FIG. 16 shows a cross-section of a drum having a generally frusto-conical surface (21), inclined downwardly from the front of the drum (22) to the end wall of the drum (23).

[0165] FIG. 17 shows a section (24) of a frusto-conical surface suitable for retro-fitting to a conventional apparatus for converting a drum having a cylindrical inner surface to a drum having a frusto-conical inner surface. Such a frusto-conical surface section is suitable as an insert for disposing between elongate protrusions (or lifters; not shown) disposed on the inner surface of the drum (not shown).

[0166] FIG. 18 illustrates the underside of an elongate protrusion (25) of the herringbone embodiment. A plurality of collecting apertures (26a, 26b, 26c) is disposed on the first side (27) of the elongate protrusion (i.e. the leading side of the elongate protrusion during rotation of the drum in a collecting direction). A first series of vanes (29a, 29b, 29c, 29d, 29e) is arranged to form a first series of U-shapes (28a, 28b), and a second series of vanes (31a, 31b, 31c, 31d, 31e) is arranged to form a second series of U-shapes (30a, 30b, 30c), wherein said first and second series of vanes and U-shapes are disposed in an opposing, interlocking but non-contacting and staggered arrangement, to form a chain of open compartments which provides a tortuous pathway from the collecting apertures to the collecting flow path and storage means (not shown).