EP2349572A1

EP2349572A1 - Mineral sizer

Info

Publication number: EP2349572A1
Application number: EP09785635A
Authority: EP
Inventors: Alan Potts
Original assignee: MMD Design and Consultancy Ltd
Current assignee: MMD Design and Consultancy Ltd
Priority date: 2008-09-19
Filing date: 2009-09-14
Publication date: 2011-08-03
Also published as: AU2009294392A1; GB0817132D0; ZA201102804B; WO2010032037A1

Abstract

A mineral sizer including two or more breaker drum assemblies rotatably housed in a housing with their axes parallel, each drum assembly including circumferentially extending groups of teeth spaced axially along the drum assembly. The housing is provided with at least one hingeable side panel of which the hinge axis is parallel to that of the drum assemblies and which provides access to the nearest drum assembly. Conveniently there is a means of securely mounting sets of cleaner combs to the innerface of the door, the teeth of such cleaner combs being located in between the teeth of the endmost drum assembly. Conveniently there is an elongate breaker bar extending longitudinally in a direction parallel to the axes of the drum assemblies, the breaker bar being located with its longitudinal axis positioned between and beneath the axes of rotation of the drum assemblies, the breaker bar including a plurality of breaker teeth spaced along its length.

Description

MINERAL SIZER

The present invention relates to a mineral sizer of the type which makes use of a breaker drum mounted in a housing for breaking lumps of mineral into smaller pieces. In particular the breaker drum is primarily configured to operate to break down mineral by a combined action, in that tensile, compressive and shear loadings are created to cause the mineral to fracture.

Such an apparatus typically comprises at least two breaker drums having breaker teeth projecting outwardly and generally substantially radially therefrom mounted side by side with parallel axes in a common housing. For example such drums might have relatively large teeth co-operating on the opposed drums to break mineral lumps down. Opposed drums are typically configured to be, though not limited to be, contra-rotating, and may rotate in either sense relative to the frame. Examples of such apparatus are described in general terms in EP0096706.

During operation, mineral breaking for reducing the material to a required size may occur both between the teeth on the opposed drums and between the teeth of a drum and a side wall of the housing. Additional structures may be provided mounted upon or contiguous with the side wall of a housing to facilitate breaking and sizing at this point, for example in the form of additional toothed structures projecting inwardly from the side wall. Structures may be provided on the side wall to clear material blockages, for example when working with sticky or plastically deformable materials. Toothed structures may combine both these functions, for example as so-called cleaner combs. WO97/041957 describes a disintegrating roller arrangement with a side wall portion movably arranged relative to the rest of the casing between an operational position and a second position where it creates such an opening of the casing that hindering material or material difficult to disintegrate may be fed out of the machine through the opening. Mineral disintegration is effected between rollers.

According to one aspect of the present invention there is provided a mineral sizer including at least two breaker drums each having circumferentially extending teeth projecting outwardly from the body of the drum and for example substantially radially therefrom, the drums being rotatably housed with their axes parallel in a housing comprising a pair of opposed side walls extending longitudinally for example in a direction parallel to the rotational axes of the breaker drums, wherein at least one of the side walls is provided with at least one hinge-mounted side panel mounted via a longitudinal hinge means so as to be movable between at least one closed configuration and at least one open configuration, at which closed configuration an inner wall of the hinge-mounted side panel is angled inwardly towards a point of closest approach to an adjacent drum, and at which open configuration external access to the internal volume defined by the housing is enabled.

In a sizer apparatus in accordance with the invention at least some of the mineral breaking occurs at a localised point of closest approach or nip point where the gap between the breaker teeth of the drum and the side wall of the housing is at its minimum. The panel is accordingly configured, and in particular is mounted, so that this is so. The inner wall of the panel thus is adapted to define, at least in the region of closest approach to an adjacent drum, a breaking surface which co-operates with the drum to contribute at least some of the mineral breaking effect. This can be contrasted with the arrangement in WO97/041957 where a disintegration zone is defined only by pairs of rolls (consisting of the two upper rolls, or an upper roll and the lower) and the side panel is merely configured as a means to open when force is exerted by oversized mineral trapped between it and an adjacent roller to feed it out rather than to break it.

In accordance with the invention, the hinge-mounted side panel is mounted such as to define at least one closed configuration where an inner wall of the side panel is at an angle to the vertical which tapers inwardly when viewed from a material supply side, which will usually be from above. That is, the wall tapers from a more open configuration above the drum to a more closed configuration at the localised nip point. The gap between the side wall and the drum teeth thus tapers in the vertical plane to provide a narrowing gap through which material is to be forced. Thus, mineral breaking occurs between a surface of the inner wall of the side panel and an adjacent roller over a wider arc. The resultant mechanical wear may be distributed over a larger proportion of the surface of the inner wall of the hinge-mounted side panel than would be the case where the wall is vertical. The wall may taper at any suitable angle, for example an angle of between 15° and 40°.

Secondly, the hinge mounting enables the side panel to be moved to an open configuration in which access to the housed volume, and for example to a breaker drum or breaker drums mounted therein, is facilitated, for example for cleaning and repair purposes.

The hinge-mounted side panel thus has at least this dual functionality. It provides a breaker surface in the closed configuration and a door in the open configuration. In a preferred embodiment, the hinge-mounted side panel is adjustable between a plurality of closed configurations in which an inner wall of the hinge-mounted side panel tapers inwardly downwards at a plurality of different angles. Thus, the angle of taper of the inner wall of the hinge- mounted side panel inwardly from a vertical plane can be adjusted. It will be understood that where used herein reference to adjustment between a plurality of closed configurations encompasses both adjustment providing a limited plurality of specific closed orientations and continuous adjustment across a range of angles of orientation. Additionally or alternatively the position of the hinge-mounted side panel may be adjustable laterally.

Adjustment in this manner may accommodate a range of material sizes and/ or (especially where specific breaker formations are disposed on the inner wall of the side panel) accommodate wear, for example of the inner wall of the side panel, cleaner combs on the side panel, breaker teeth or surface of the breaker drum body in channels between breaker teeth as the case may be.

The inner wall of the hinge-mounted side panel may be planar or more preferably concave to enhance the taper effect.

The inner wall will preferably be provided with a wear resistant surface for example in the form of an attachable wear plate and/or composed of wear resistant material, at least at those points making engagement with material in use.

At least some of the breaking action of an apparatus in accordance with the invention takes place at and in the vicinity of the localised nip point between the side wall and the rotating drum in use. Thus, the inner wall of the panel constitutes, at least in the region of closest approach to an adjacent drum, a breaking surface which co-operates with the drum to contribute at least some of the mineral breaking effect. Preferably, additional breaking formations such as tooth formations, or means to mount such additional breaking formations, are provided on an inner wall of the hinge-mounted side panel. Such means or formations may extend longitudinally along at least a substantial part of the length of the wall. Conveniently, these means or formations may be accessed externally and/ or internally when the hinge-mounted side panel is in an open configuration.

Advantageously therefore, to facilitate the breaking action, when teeth are mounted in accordance with the foregoing an inner wall of the hinge- mounted side panel is provided with a longitudinally extending series of teeth projecting transversely therefrom. These teeth interact functionally with the teeth of the drum, for example being arranged such that during rotation of a drum teeth projecting from the drum are arranged to project towards and for example into spaces between teeth projecting from the inner wall of the hinge-mounted side panel.

Preferably, at least one hinge-mounted side panel is provided on each of the pair of opposing side walls of the housing. Conveniently, a plurality of discrete and separately operable hinge-mounted side panels may be provided disposed along the length of a side wall of the housing.

Preferably, an inspection port with cover is additionally provided in at least one end wall of the housing.

In an apparatus in accordance with the invention a breaking action may be envisaged to occur at either or both of a point of closest approach between the teeth of an adjacent pair of breaker drums and between each outermost breaker drum and its corresponding side wall. The precise breaking action may be determined for example by rotation direction and tooth configuration. It will be appreciated that while for many applications a single pair of breaker drums may be provided, and examples hereinbelow are discussed in those terms, the invention is equally applicable to the provision of mineral sizers comprising a plural array of more than two breaker drums rotatably housed in a housing as above described with their axes parallel and/or to a combination apparatus comprising multiple separately housed breaker drums arrayed in parallel. The invention encompasses drums mounted for rotation in either direction in any combination, and depending on application it may be desirable to have adjacent drums contra-rotating or rotating in the same direction, and where three or more drums are provided to have adjacent pairs rotating in either or both senses.

In a preferred modification at least some of the teeth on a drum are arranged with a progressive relative offset. That is, the rotary position of each such tooth is offset relative to its neighbour. In this way a point of engagement for a given particle size moves progressively longitudinally and distributes the load along a drum during use. For example the teeth are thereby arranged so as to define a series of discrete circumferentially spaced progressive and for example helical formations extending along the drum, such term being understood as encompassing a longitudinal series of teeth with a progressive offset causing teeth in the series to be disposed in scrolling manner about the drum, whether in a strictly mathematical helix or part thereof or otherwise.

Preferably the teeth on at least a pair of adjacent drums are arranged in discrete helical formations extending along each drum. Preferably the axial positions of the drums are arranged so that during rotation each tooth of a helical formation on one drum projects towards and for example into the spacing between adjacent teeth of a helical formation on the other drum.

In a possible embodiment, the teeth on each drum are conveniently arranged in circumferentially extending groups of teeth, the groups of teeth on one drum being located between adjacent groups of teeth on the other drum, the teeth on at least one of said pair of drums being arranged to define a series of discrete circumferentially spaced progressive and for example helical formations extending along the drum as above described.

More completely, in accordance with a preferred embodiment there is provided a mineral sizer including at least two breaker drum assemblies rotatably housed in a housing with their axes parallel, each drum assembly including circumferentially extending groups of teeth, the groups being spaced axially along the drum assembly to define a circumferentially extending channel between adjacent circumferential groups of teeth, the drum assemblies being arranged such that each circumferential group of teeth on one drum assembly is located to enter a circumferentially extending channel between a pair of neighbouring circumferential groups of teeth on the other drum assembly, the cross-sectional shape and size of each tooth and channel being complementary such that the sides and tip of a tooth when entering a channel are closely spaced from the sides and bottom of the channel, wherein at least one of the side walls is provided with at least one hinge-mounted side panel mounted via a longitudinal hinge means so as to be movable between at least one closed configuration and at least one open configuration, at which closed configuration an inner wall of the hinge-mounted side panel tapers inwardly downwards, and at which open configuration external access to the internal volume defined by the housing is enabled. Preferably, the drums of the or each adjacent pair are arranged in use to rotate in opposite directions. A pair of such contra-rotating drums may rotate such as to rotate inwardly towards or outwardly from their mutual point of closest approach when viewed from above.

In one variant of this mode of operation for such a pair of drums, the drums are arranged in use to rotate in opposite directions, the teeth are arranged in helical formations, the helical formations on one drum being arranged in an opposite sense to the helical formations on the other drum so that the helical formations on both drums tend to move large pieces of mineral deposited thereon in the same axial direction.

In another variant of this mode of operation for such a pair of drums, the drums are arranged to rotate in opposite directions, the helical formations on one drum being arranged in the same sense to the helical formations on the other drum so that the helical formations on one drum tend to move large pieces of mineral in an opposite axial direction to the helical formations on the other drum.

It will be understood with reference to the uses of similar apparatus that material for sizing is typically fed under gravity from a position above the breaker drums to be broken and sized under the action of the breaker drums. The comminuted material is then passed onto suitable conveyance means for onward conveying. The axis of a breaker drum, or the plane in which the parallel axes of a plurality of breaker drums lie, will typically be in a horizontal direction. References to orientation hereinabove, in particular in relation to the angle of the side walls as being angled to the vertical, or extending downwardly, which are intended to give indications of relative orientation of the elements of the invention, should be understood in this context. References to typical intended use are for convenience only in assisting an understanding of these relative orientations, and are not intended to limit the invention by such use. Machines may be operated whilst in an inclined orientation for example, although usually by no more than 45° and open to be fed from above.

Conveniently, an adjacent pair of drum assemblies is additionally provided with an elongate breaker bar extending longitudinally in a direction parallel to the axes of the drum assemblies, the breaker bar being located with its longitudinal axis positioned between and beneath the axes of rotation of the drum assemblies, the breaker bar including a plurality of breaker teeth spaced along its length. Each breaker tooth of the breaker bar is conveniently disposed to project upwardly into a channel defined between a pair of circumferential groups of teeth on one of the drum assemblies. Preferably each breaker bar tooth is of a size and shape complementary to the channel into which it projects so as to be closely spaced from the sides and bottom of the channel.

A breaker drum may be of monolithic construction but is more typically an assembly of components, for example comprising an elongate body on which tooth carrying structures and/ or teeth may be mounted to complete the assembly.

In a convenient embodiment, a breaker drum assembly comprises a main shaft with drive means and a plurality of toothed annuli mounted on the drive shaft, adjacent annuli being axially spaced along the shaft, each annulus being fixedly connected to the shaft.

Preferably each toothed annulus includes an annular boss and one or more rows of teeth spaced circumferentially about the boss, each tooth extending generally radially from the boss. The number of teeth in a row is preferably in the range of 3 to 8. A boss may carry a plurality of longitudinally spaced rows.

Each toothed annulus may be a unitary metal casting or forging or profile cut from metal plate wherein the teeth are integrally joined with the annular boss.

Each tooth may define a breaker tooth per se. Alternatively each tooth may define an inner core or horn of a breaker tooth wherein the outer shape of the breaker tooth is defined by a tooth sheath or wear plates secured to the horn, or comprises welded layers of wear resistant material built up on the horn.

Aspects of the present invention are hereinafter described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a mineral sizer according to an embodiment of the present invention;

Figure 2 is an end elevation of the mineral sizer of figure 1 ;

Figure 3 is a side elevation of the mineral sizer of figure 1 ; Figure 4 is a plan view from above of the mineral sizer of figure 1 ;

Figure 5 is a plan view from above of the mineral sizer of figure 1 in alternative configuration;

Figure 6 is a part sectional plan view of the mineral sizer shown in Figure

1 with detail of hinge-mounted side panel attached thereto; Figure 7 is a perspective view from above of a breaker bar assembly for optional use in the apparatus of figure 1 ;

Figure 8 is a similar view to figure 7 with teeth removed.

A mineral sizer according to an embodiment of the present invention is shown generally at 10 in Figures 1 to 5. The sizer 10 includes a box-like housing 12 having opposed side walls 14, 16 and opposed end wall assemblies 18, 20. A pair of breaker drums 30 are rotatably mounted in the housing 12 so as to extend longitudinally from one end wall assembly 18 to the other end wall assembly 20.

Each breaker drum 30 is in the embodiment driven independently by an individual motor 36 via a gear box 38. Preferably, each motor is an electric rotary motor. However, it will be appreciated that other forms of motor, such as a fluid motor, may be used. It will be appreciated that other forms of drive arrangement might be appropriate. For example each breaker drum may be driven independently by a single motor system, or breaker drums may be driven in a co-ordinated manner, for example by a single motor or independent motors in combination with suitable timing means.

Each breaker drum carries a plurality of circumferentially extending groups of teeth 43, the groups being spaced axially along each drum assembly to define a circumferentially extending channel between adjacent circumferential groups of teeth. The drum assemblies are arranged such that each circumferential group of teeth on one drum assembly is located to enter a circumferentially extending channel between a pair of neighbouring circumferential groups of teeth on the other drum assembly.

The plurality of circumferentially extending groups of teeth thus define a series of generally longitudinal teeth arrays. It is desirable that, the rotary position of a given tooth 43 relative to its longitudinal neighbour is off-set by a predetermined increment such that the teeth on a given shaft extend along a predetermined progressive and for example generally helical path in order to define a series of discrete scrolls of teeth as above described and as disclosed for example in EP0167178. In the illustrated machine, the increment by which adjacent teeth are off-set is such that the starting point of each discrete scroll at one end of the drum assembly is off-set from the finishing point of the scroll at the other end of the drum assembly by an angular distance equivalent to two teeth pitch spacings between teeth 43.

The drums are arranged such that during rotation each tooth of a formation on one drum projects towards and for example into the spacing between adjacent teeth of the other drum. This is illustrated in figure 4 where the drums are spaced apart such that teeth project towards each other but to not enmesh and in figure 5 where the drums are more closely mounted and the teeth enmesh.

Conveniently each breaker drum 30 is a modular assembly including a shaft and a plurality of toothed structures mounted thereon.

In the embodiment each breaker drum assembly 30 comprises a shaft 31 which is rotatably mounted at opposite ends in respective end wall assemblies 18, 20 via bearings (not shown). The shaft is conveniently of solid section and is preferably formed from a suitable steel or similar material. Each breaker drum assembly 30 further includes a plurality of toothed structures 40 from which a plurality of teeth 43 project substantially radially, the teeth 43 per se defining breaker teeth. The teeth may be of any suitable familiar form. Each toothed structure 40 is located on a shaft 31 and is fixedly secured thereto for example by welding, provision of keyways, by means of a tight mechanical fit or otherwise.

Preferably, the distance between the breaker drum assemblies 30 is adjustable such that the size of the effective passageway therebetween can be varied, for example to control the flow of undersized mineral. In the illustrated embodiment removable spacer packers 39 may be used to effect adjustment of the distance between the centres of the breaker drum assemblies 30, as can be appreciated by a comparison of the configurations in figures 4 and 5. Alternative means can readily be envisaged. For example in one alternative arrangement, this adjustment of the distance between the breaker drums may be achieved by fixedly mounting one breaker drum on the support frame, slidably mounting the other breaker drum on the support frame, and providing motive means, such as a pair of hydraulic rams for causing relative movement between the breaker drums.

The mineral sizer 10 described above may be modified by the inclusion of additional breaker drums to define a row of breaker drums exceeding the simple pair illustrated in figure 1. In such a case all centre distances are preferably made relatively adjustable, for example in the manner above.

A cross section through part of the apparatus of figure 1 better illustrates the structure and operation of the hinge-mounted closure formation, as represented in figure 6.

The side walls 14, 16 of the housing are each provided with a pair of hinge-mounted side panels 45 mounted via hinge means 47 to have a longitudinally extending hinge axis so as to be movable between a closed configuration (see left hand panel in figure 6) and an open configuration (see right hand panel). In the closed configuration an inner wall of the hinge-mounted side panel tapers inwardly downwards. In the open configuration external access to the internal volume defined by the housing is enabled. As can be seen in figure 6 the side closure panel 45 comprises a door formation 46 rotatably mounted on a hinge means 47 so as to be rotatable from an open to a closed position. Both positions are illustrated in the figures. An inner wall surface of the door formation 46 is provided with a plate of hard wearing material 48, and towards a lower end a toothed formation 49 of similarly wear resistant material projects outwardly from, and is attached to the door formation. In practice a plurality of teeth will be disposed longitudinally along the inner wall of the panel.

The teeth 49 may for example comprise cleaner combs of relatively conventional design, and may be fixed to the hinged side panel by any suitable removable or semi-permanent means such as welding or bolting. Similar attachments may be envisaged for the wear plates 48. Embodiments could be envisaged dispensed with the teeth 49 altogether, and simply relied on the inner wall surface of the hinged side panel, in conjunction with an adjacent drum, to effect the breaking action. The hinged side panel would always require at least a layer of wear resistant material on this inner surface, such as the wear plate 48.

In the closed configuration the hinged side panel is at an angle to the vertical, so that the gap between its inner wall and the teeth 43 of its corresponding drum 30 narrows from a relatively wide gap towards the top to a localised nip point, in the preferred embodiment lying below the rotational axis of the drum 30, and at which point the teeth 49 of the hinged side panel interact with the breaker teeth 43. This arrangement provides a more gradual tapering gap than would be the case for a vertical wall, in the embodiment narrowing at an angle of around 30°, so that mineral breaking occurs over a wider arc. The fact that breaking occurs over a wider arc means that the breaking loads and resultant mechanical wear are distributed over a larger portion of the wall of the hinged side panel and not just local to the toothed formations 49 making up the cleaner combs.

In the illustrated embodiment, this effect is enhanced in that the wall of the hinged side panel is concave, although the invention is not limited to such concave panels.

The angle that the hinged side panel makes to the vertical in a closed configuration may be fixed at a single desired angle, or may be adjustable. Additionally or alternatively the lateral position of the hingeable side panel may be adjustable. Either or both forms of adjustment may be useful in accommodating differing sizing requirements and/or in moving the cleaner combs to accommodate wear of the combs themselves or of parts of the drum.

In the preferred embodiment, a single pair of drum assemblies is illustrated, which are mounted to be contra-rotating, and to be rotating outwards (when viewed from the top). Other arrangement of more than two drums and/or arrangements where adjacent pairs of drums rotate inwardly or are not contra-rotating are also known and within the scope of the invention.

However, in the envisaged embodiment, the cleaner combs have an additional functionality which would not be of the same significance in the case of inwardly rotating drum assemblies, in that they effect further breaking of the material in conjunction with the breaker teeth on an adjacent, and locally downwardly rotating, drum. From a design point of view with respect to this function it is desirable for the teeth to be mounted below the centre line of the drum assemblies. If the wall were vertical then the teeth would have to be longer and because they are cantilevered this would weaken them. The angle to the vertical and the curve of the hinged side panel in accordance with the invention brings the point at which the teeth 49 are mounted closer to the desired position so that they do not have to be as long and are less prone to breakage. This is a further advantage of the angled orientation, and in the preferred embodiment of the concave structure.

In a closed configuration the hinged side panel additionally closes an aperture in a side wall of the housing. In the open configuration this aperture may be accessed externally to permit maintenance work on and cleaning of the drum assemblies, for example to permit the fitment of individual teeth or panels, annuli or bosses of multiple teeth. The hinged side panel and associated aperture must be suitably sized and shaped to facilitate this.

The side panel may be adapted to provide, or to be used with, various means to facilitate opening and closing, such as hydraulic rams, winches or the like. The side panel may incorporate actuation means such as hydraulic rams or winches to facilitate opening, or may include mounting positions for external actuation means. Actuation means may be positioned to push the side panel up rather than pull it up. The side panel of the embodiment is provided with a hydraulic ram 53 to effect lifting for opening purposes. Alternatively the lug 51 on an outside surface of the door may be used. Of course the invention is not limited to this particular embodiment.

The mineral breaker preferably includes a breaker bar assembly located beneath the drum assemblies 30. The provision of a breaker bar assembly assists in ensuring that long thin lumps of mineral cannot pass so readily through without being broken down. An example of breaker bar assembly 70 as illustrated in Figures 7 and 8 is elongate and extends longitudinally in a direction parallel to, and centrally located between, the axes of rotation of the drum assemblies 30.

The breaker bar assembly 70 includes a main elongate support body 71 which is secured at each end to a respective end wall assembly 18, 20 of housing 12. The body 71 is of generally T shaped cross-section having a horizontal part 71 a and a vertical part 71 b. Preferably a strengthening bar 72 extends along the upper edge of the vertical part 71 b. The body 71 has mounted thereon a plurality of breaker teeth 72.

The breaker teeth 72 are each of blade like form and are conveniently arranged to project upwardly into the annular recess defined between adjacent toothed annuli on one drum.

The cross-sectional shape and size of each tooth 72 is preferably similar to that of this channel so that each tooth 72, in cross-section substantially fills the channel. This has the effect of enabling the leading face 72F of teeth 72 to act as scrapers to clear material adhering between adjacent annuli; this is particularly useful when handling sticky materials such as clays or tar sand.

In addition since each tooth 72 substantially fills each channel, the teeth 72 on the breaker bar act to choke flow of material emerging from between the drum assemblies 30. This has the effect of agitating material emerging from between the drum assemblies 30 and so assists in dislodging any wedged lumps located in between adjacent teeth. These lumps are then broken down further by interaction between breaker teeth 43 and breaker bar teeth 72 between which it passes. As seen in Figures 7 and 8, the teeth 72 are arranged in two longitudinally extending rows 74,75 wherein the teeth 72 in one row co-operate with one drum assembly 30 and the teeth 72 in the other row co-operate with the other drum assembly 30.

Teeth 72 in a given row are spaced apart in the longitudinal direction of support 71 to define a groove or recess 78 through which the teeth on an associated drum assembly pass during rotation of the drum assembly 30.

The groove 78 has sides defined by opposed sides of adjacent teeth 72 on one row and a bottom 79 defined by a side edge of an intermediate tooth 72 from the other row.

Preferably the teeth 72 are formed in blocks of teeth 80 which straddle the vertical part 71 b of the elongate support 71 and are secured thereto by through bolts (not shown) passing through bores 73 formed in the vertical part 71 b and bores 83 formed in blocks 80. Preferably the blocks 80 are each cast from a suitable metal and each comprise a number of teeth 72 for forming one row 74 and a number of teeth 72 for forming the other row 75.

Conveniently the number of teeth 72 in each block 80 is five with three teeth 72 on one side and two teeth 72 on the other side. Thus by mounting adjacent blocks 80 on the vertical part 71 b with alternate blocks 80 having three teeth 72 on one side of part 71 b and two teeth 72 on the other side of part71 b it is possible to create the two rows of teeth 74,75.

The elongate body 71 is preferably provided with mounting flanges 90 at each end via which the breaker bar assembly 70 may be mounted on the opposed end walls 18, 20 of the breaker housing.

It is envisaged that the height of the breaker bar assembly 70 relative to the drum assemblies 30 may be adjusted by the placement of shims beneath flanges 90.

In the example described in Figure 1 each tooth 43 per se defines a breaker tooth. It is envisaged that the teeth 43 may alternatively define the core or horn to which a tooth cap or wear plate may be attached to define the breaker tooth. Alternatively a tooth may comprise welded layers of wear resistant material built up on the horn. Examples of breaker teeth having a core or horn and a covering cap are described in EP0167178.

Claims

1. A mineral sizer including at least two breaker drums having circumferentially extending teeth projecting outwardly from the body of the drum, the drums being rotatably housed with their axes parallel in a housing comprising a pair of opposed side walls extending longitudinally, wherein at least one of the side walls is provided with at least one hinge-mounted side panel mounted via a longitudinal hinge means so as to be movable between at least one closed configuration and at least one open configuration, at which closed configuration an inner wall of the hinge-mounted side panel is angled inwardly towards a point of closest approach to an adjacent drum the panel being configured such that at least some of the mineral breaking occurs at the point of closest approach where the gap between the breaker teeth of the drum adjacent and the side wall of the housing is at its minimum, and at which open configuration external access to the internal volume defined by the housing is enabled.

2. A mineral sizer in accordance with claim 1 wherein the inner wall of the hinged-mounted side panel is concave.

3. A mineral sizer in accordance with any preceding claim wherein an inner wall of the hinge-mounted side panel is provided with a longitudinally extending series of teeth projecting transversely therefrom and arranged such that during rotation of a drum teeth projecting from the drum are arranged to project towards spaces between teeth projecting from the hinge-mounted side panel.

4. A mineral sizer in accordance with any preceding claim wherein the hinge-mounted side panel is adjustable between a plurality of closed configurations in which an inner wall of the hinge-mounted side panel is angled inwardly at a plurality of different angles.

5. A mineral sizer in accordance with any preceding claim wherein the inner wall is provided with a wear resistant surface and/or composed of wear resistant material.

6. A mineral sizer in accordance with any preceding claim wherein at least one hinge-mounted side panel is provided on each of the pair of opposing side walls of the housing.

7. A mineral sizer in accordance with any preceding claim, wherein at least some of the teeth on a drum are arranged with a progressive relative offset.

8. A mineral sizer in accordance with claim 7 wherein the teeth are thereby arranged so as to define a series of discrete circumferentially spaced progressive formations extending along the drum with a progressive offset causing teeth in the series to be disposed in scrolling manner

9. A mineral sizer in accordance with claim 8 wherein the teeth and drum are arranged so as to define a series of discrete circumferentially spaced helical formations extending along the drum.

10. A mineral sizer in accordance with claim 9 wherein the teeth on at least a pair of adjacent drums are arranged in discrete helical formations extending along each drum.

11. A mineral sizer in accordance with any preceding claim wherein the teeth on each drum are arranged in circumferentially extending groups of teeth, the groups of teeth on one drum being located between adjacent groups of teeth on the other drum.

12. A mineral sizer including at least two breaker drum assemblies rotatably housed in a housing with their axes parallel, each drum assembly including circumferentially extending groups of teeth, the groups being spaced axially along the drum assembly to define a circumferentially extending channel between adjacent circumferential groups of teeth, the drum assemblies being arranged such that each circumferential group of teeth on one drum assembly is located to enter a circumferentially extending channel between a pair of neighbouring circumferential groups of teeth on the other drum assembly, the cross sectional shape and size of each tooth and channel being complementary such that the sides and tip of a tooth when entering a channel are closely spaced from the sides and bottom of the channel, wherein at least one of the side walls is provided with at least one hinge-mounted side panel mounted via a longitudinal hinge means so as to be movable between at least one closed configuration and at least one open configuration, at which closed configuration an inner wall of the hinge-mounted side panel tapers inwardly downwards, and at which open configuration external access to the internal volume defined by the housing is enabled.

13. A mineral sizer in accordance with any preceding claim wherein an adjacent pair of drum assemblies is additionally provided with an elongate breaker bar extending longitudinally in a direction parallel to the axes of the drum assemblies, the breaker bar being located with its longitudinal axis positioned between and beneath the axes of rotation of the drum assemblies, the breaker bar including a plurality of breaker teeth spaced along its length.

14. A mineral sizer in accordance with any preceding claim wherein an adjacent pair of drum assemblies is additionally provided with means whereby the distance between the breaker drum assemblies is adjustable such that the size of the effective passageway therebetween can be varied.

15. A mineral sizer in accordance with any preceding claim further comprising rotational drive means by means of which each drum may be rotated with an independently controlled speed and direction.