WO2011021037A1

WO2011021037A1 - Mineral conveyor

Info

Publication number: WO2011021037A1
Application number: PCT/GB2010/051368
Authority: WO
Inventors: David Pitchford
Original assignee: Mmd Design & Consultancy Limited
Priority date: 2009-08-20
Filing date: 2010-08-19
Publication date: 2011-02-24

Abstract

A mineral conveyor is described comprising a plurality of plates joined together to provide a conveyor surface and a conveyor drive apparatus adapted to drive the plates comprising the conveyor surface around a closed-loop continuous path. At least one of the plurality of plates is a moveable plate adapted to move between a closed position where the conveyor surface is continuous and an open position where the conveyor surface is discontinuous. An apron plate feeder and a processing assembly incorporating such a mineral conveyor are described.

Description

MINERAL CONVEYOR

The present invention relates to mining equipment and more specifically to a mineral conveyor system of the type used in the mining industry.

Mineral conveyor systems are often arranged beneath tipping points to convey mineral mined from a mine face to a mineral sizer or other crushing device. Typically, material is directly fed into a hopper by an excavator or mining shovel before being drawn up a mineral conveyor or 'apron plate feeder', as otherwise known in the art, to be discharged into the mineral sizer or other crushing device. Other known terms for such mineral conveyors are plate feeders, chain feeders, feeders, plate conveyors etc. Reduced mineral from the crusher is subsequently discharged on to flexible belt conveyor to be transported away from the mining location.

An apron plate feeder typically comprises a closed-loop continuous conveyor surface with suitable drive apparatus. As shown in Figures 1 to 4, an example of a known apron plate feeder 10 is provided with a chain drive system comprising a pair of spaced head sprockets 12 and a pair of spaced tail sprockets 14 mounted to a main frame 16. A heavy duty chain 18 connects each of the head sprockets 12 with a corresponding tail sprocket 14 to provide two spaced chains 18. A variable speed hydraulic or electro-mechanical drive unit is coupled to the head sprockets 12 to rotatably drive the chains 18. The top strand of each chains 18 is mounted on rollers 22 which are rotatably attached to the main frame 16. The chains 18 and rollers 22 vary in size depending on the application and operating loads they will be subject to. Other drive systems may be envisaged. The conveyor surface is formed of conveyor plates 24 fixed to the chain 18 by bolts 27 to provide a continuous conveyor surface for conveying material deposited thereon. The conveyor plates 24 can be fabricated or made from custom rolled sections of a desired width depending on the volume of material which requires processing. The conveyor plates 24 have overlapping edges in an attempt to prevent fine material spilling between the plates 24 and elastically deform to withstand impact loads when material 26 is deposited thereon. The conveyor plates form a continuous conveyor surface having an upper portion 20 or top strand for conveying material. A lower portion 21 or bottom strand and curved end portions passing around spaced head and tail drive assemblies complete the loop. As described above, the drive assemblies may comprise head and tail sprockets, pulleys or drums coupled by corresponding chains or belts.

In use, the apron plate feeder is typically inclined to the ground at a desired angle and arranged to convey excavated mineral or ore from an input end positioned at the mine face at or near ground level up to a discharge end positioned over a hopper or the like to be discharged into the mineral sizer or crushing device.

Due to the nature of the environment in which the apron plate feeder operates, the input end of the apron plate feeder can potentially be buried beneath excavated material which is being loaded on to the apron plate feeder by a mining shovel.

A problem exists during operation where material slips between adjacent plates of the conveyor surface and into the cavity between the top strand and bottom strand of the apron plate feeder. It is also known for material to enter the cavity from a side of the main frame in the vicinity of the input end of the apron plate feeder which is surrounded by excavated material at the mine face. As the apron plate feeder is a closed-loop arrangement, the material which has entered the cavity between the top and bottom strands is trapped and is unable to escape. Due to the rotational direction and elevation of the apron plate feeder, the trapped material tends to collect at the input end thereof and this situation is worsened if the material is of a sticky, muddy nature because it builds up over time in a snowball effect.

The weight of the trapped material inside the apron plate feeder increases the operating load thereon and can damage equipment local to the input end, and must be removed manually at regular intervals. This undesirably requires costly downtime of the mining equipment.

A first aspect of the present invention provides a mineral conveyor comprising:

- a plurality of plates joined together to provide a conveyor surface; - a conveyor drive system adapted to drive the plates comprising the conveyor surface around a closed-loop continuous path;

wherein at least one of the plurality of plates is a moveable plate adapted to move between a closed position where the conveyor surface is continuous and an open position where the conveyor surface is discontinuous.

Thus, a mineral conveyor in accordance with the invention comprises a continuous plate conveyor of generally familiar design. In operation, the drive system rotatably drives the plates around a closed-loop continuous path in such a manner as to define an upper portion of the conveyor surface for conveyance of minerals and a lower portion and end portions passing around head and tail drive assemblies complete the continuous closed-loop. Material extracted from the mine face by a mining shovel is deposited on plates forming the upper portion of the conveyor surface at an input end of the mineral conveyor. The input end may be positioned in the vicinity of the mine face. The material is conveyed from the input end along the upper portion of the conveyor surface towards a discharge end of the mineral conveyor which may for example be positioned over a discharge hopper above a mineral sizer or other crushing device.

During conveyance of the material deposited on the upper portion of the conveyor surface, it is known for fine material to slip between adjacent plates and into a cavity between the upper and lower conveyor portions. As described above, this material is known to build up and undesirably must be manually removed from the cavity.

The invention is characterised in that at least one of the plurality of plates is a moveable plate adapted to move between a closed position where the conveyor surface is continuous and an open position where the conveyor surface is discontinuous. When the moveable plate is in the open position, access to the cavity between the upper and lower portions of the conveyor surface is permitted through an opening provided thereby.

As the plates are moved about the continuous closed-loop path by the drive assembly, the movable plate(s) are correspondingly moved. It is possible to position an opening in the lower portion of the conveyor surface so that it is located where the build up of material is located. The material may then be caused to fall under the influence of gravity or otherwise be removed through the opening and from the cavity between the upper and lower portions of the conveyor surface of the mineral conveyor. Desirably, the material is removed from the cavity during operation of the mineral conveyor without human interaction and without requiring costly downtime of the conveyor.

In a possible arrangement, the moveable plate may be adapted to move from the closed position to the open position when positioned to form part of the lower conveyor portion and/or end portions. The moveable plate may be adapted to move from the open position to the closed position when positioned to form at least part of the upper conveyor portion thereby to be continuous for conveying material.

Suitably the moveable plate may be adapted to move between the closed position and the open position by action of gravity. When the moveable plate is moved from the upper portion of the conveyor into an end portion and subsequently the lower portion of the conveyor, gravity may suitably move the plate from the closed position to the open position. In this case, the at least one moveable plate would continuously open and close as it is continuously moved around the closed-loop path of the mineral conveyor. This would desirably require no power and would minimise the number of parts which would otherwise require maintenance.

Suitably, retaining means may be provided to tend to retain the moveable plate in the closed position against the action of gravity. In one possible case, such retaining means may be adapted to allow the moveable plate to move between the closed position and the open position by action of gravity only above a pre-determined opening load, for example in use attributable to a particular weight of fouling material that it is desired to release. Additionally or alternatively, retaining means may comprise locking means activatable to selectively lock the moveable plate in the closed position when it is not desirable that it should open by action of gravity and deactivated when desired for gravity to move the moveable plate to the open position. Suitable retaining means may comprise a mechanical mechanism tending to resist opening of the moveable plate. Alternatively, one or more electromagnets may be activated to tend to hold the moveable plate in the closed position.

Additionally or alternatively to action under gravity, the moveable plate may be adapted to move between the closed position and the open position by provision of actuation means causing an opening and/or closing force to be applied to the moveable plate. Suitably the actuation means may be adapted to allow the moveable plate to be selectively moved between the closed position and the open position, and vice versa reciprocally. It may not be desirable for the moveable plate to

continuously open in the lower and/or end portions of the conveyor and close in the upper portion of the conveyor and only selectively at desired times. For example, the moveable plate may be adapted to be moved from the closed position to the open position at a desired location when in the lower conveyor portion and/or an end portion. Suitably, the desired location may be in the vicinity of a build-up of material in the cavity between the upper and lower conveyor portions.

Suitably the actuation means may comprise mechanical, electrical or electromagnetic actuation means to selectively open and/or close the moveable plate during operation of the mineral conveyor. For example, the actuation means may comprise pneumatic or hydraulic rams or electrical solenoids or electric motors such as rotary motors or

electromagnets, guide rails or mechanical mechanisms or combinations of the same which move the moveable plate from the closed position to the open position to provide an opening in the otherwise continuous conveyor surface.

Control means may be provided to cause such actuation means or retaining means to be operated under user control, automatically on the basis of a determination of plate position, automatically in response to a determination of build up of material in the cavity or in combination of these. Alternatively to such additional actuation means, the moveable plate may be adapted, for example, by appropriate mounting configuration to be self- actuating.

Preferably the moveable plate is rotatably moveable relative to an adjacent plate.

Suitably to effect this, the moveable plate may be pivotally mounted to the conveyor drive system. For example, the moveable plate may be pivotally mounted to transmission means of the drive system such as a chain or belt.

In a preferred embodiment, the moveable plate is pivotally attached to an adjacent plate Suitably the plurality of plates including the adjacent plate are mounted to transmission means of the conveyor drive system such as a chain or belt by suitable means such as one or more bolts.

Suitably a hinge may be disposed proximal to a leading edge or trailing edge of the moveable plate relative to a direction of movement of the plate to provide the pivotal attachment. Preferably the hinge is proximal to a leading edge of the moveable plate. Preferably the moveable plate trails the adjacent plate relative to the direction of movement of the conveyor. Desirably, this allows the moveable plate to move relative to the adjacent plate towards the open position at least when the moveable plate forms part of the lower portion of the conveyor. As the conveyor is often inclined for conveying mineral from a lower input end up to a higher discharge end positioned for example over a mineral sizer of a mobile mining rig, it is desirable for the moveable plate to be in the open position at least when moving past the lowest point of the conveyor. Where the conveyor is inclined, the build up of material within the cavity of the conveyor, as described, generally occurs at the lowest point of the cavity typically being around a lower drive assembly at the input end of the conveyor. Preferably the moveable plate moves towards the open position when in the lower portion or end portions of the conveyor. Further preferably, the pivotal arrangement of the moveable plate and the adjacent plate provides actuation means for moving the moveable plate towards the open position. Preferably the moveable plate is forced towards the open position when moving from the lower portion of the conveyor to an end portion of the conveyor. Preferably the moveable plate is forced towards the open position when in the vicinity of a conveyor drive assembly. Preferably the moveable plate is moved towards the open position when being driven around a tail drive assembly of an inclined conveyor..

Suitably the adjacent plate comprises at least first and second lugs extending therefrom. Suitably the first and second lugs are spaced, each lug being provided at or near opposing ends of the adjacent plate.

Suitably the first and second lugs comprise an aperture near a free end. Suitably the moveable plate comprises corresponding first and second lugs for engagement with the first and second lugs of the adjacent plate. The first and second lugs of the moveable plate suitably comprise corresponding apertures.

Suitably corresponding pins engage through the apertures of the first and second lugs to pivotally attach the moveable plate to the adjacent plate.

Preferably the pivotal attachment is provided within limits defined by a trailing edge of the adjacent plate and a leading edge of the moveable plate relative to the direction of the conveyor. Preferably the pivot is approximately equidistant between these limits. To this effect, the first and second lugs of the adjacent plate may extend towards the moveable plate and the first and second lugs of the moveable plate may extend towards the adjacent plate.

Preferably the trailing edge of the moveable plate is overlapped by the leading edge of a neighbouring plate trailing the moveable plate. When the plates form part of the lower portion of the conveyor, the trailing edge of the moveable plate is suitably above the leading edge of the trailing neighbouring plate. This overlap desirably supports the moveable plate and prevents it moving towards the open position under the influence of gravity when it forms part of the lower portion of the conveyor. Preferably the trailing edge of the moveable plate is reduced relative to the trailing edge of the neighbouring plate. In other words, the trailing edge of the moveable plate does not extend as far as the trailing edge of the neighbouring plate. When the plates are in the vicinity of a drive assembly and enter a curved end portion of the conveyor, the plates are moved apart and the overlap is decreased. Due to the reduced trailing edge of the moveable plate, there becomes a point where no overlap exists. At this point, the trailing edge of the moveable plate is unsupported and disengages from the trailing neighbouring plate allowing the moveable plate to move towards the open position.

Preferably the degree of movement of the moveable plate towards the open position is controlled. Suitably the leading edge of the moveable plate overlaps the trailing edge of the adjacent plate. Whilst moving around a curved end portion of the conveyor, the leading edge of the moveable plate is below the trailing edge of the adjacent plate. The plates are adapted to ensure an overlap always exists. This desirably provides a limit to the movement of the moveable plate towards the open position whilst allowing sufficient movement for a build up of material to exit the cavity of the conveyor.

As the plates move from the end portion towards the upper portion of the conveyor to form part of the mineral conveying surface, the plates are moved towards each other to overlap once again. This overlap ensures the moveable plate is in the closed position whilst forming the continuous conveyor surface in the upper portion of the conveyor.

Suitably the leading edge of the moveable plate is complementarily shaped with the trailing edge of the adjacent plate and the trailing edge of the moveable plate is complementarily shaped with the leading edge of a neighbouring plate trailing the moveable plate. This ensures that adjacent and neighbouring plates overlap closely with the moveable plate and so that the plurality of plates provide a substantially continuous conveyor surface. The moveable plate will move towards the open position when leaving the upper conveyor portion and entering a curved end portion of the conveyor, such as the end portion in the vicinity of the head conveyor assembly of an inclined conveyor. In order to prevent material entering the cavity of the conveyor, such as material falling from an elevated discharge end portion of an inclined conveyor into a mineral sizer for example, a guard may be provided around the curved discharge end portion of the conveyor.

Suitably the guard may be complementarily shaped to fit around the curved end portion of the conveyor. The guard may be suitably spaced therefrom to prevent interference between the plates and the guard whilst preventing the ingress of material between the plates and the guard. The guard may suitably comprise cleaning means, such as a brush or scraper, to remove material from the plates and/or prevent material ingress between the guard and the plates.

In an alternative embodiment, the moveable plate may slideably move relative to an adjacent plate. Suitably the direction of slide may be substantially parallel with the conveyor surface. Suitably the conveyor surface may comprise a plurality of moveable plates to provide the possibility of a plurality of openings when the moveable plates are moved to the open position. A plurality of moveable plates adapted to be moved to the open position desirably provides a plurality of openings for trapped material to exit the cavity of the mineral conveyor. In this embodiment of the invention, material can be removed from the cavity of the mineral conveyor quicker than would be the case with one moveable plate. The plurality of moveable plates may be provided so as to be generally evenly spaced about the continuous closed loop. The plates making up the conveyor surface are driven in use around a closed-loop continuous path by suitable a conveyor drive system. The conveyor drive system is not directly pertinent to the invention and various systems will be familiar. In a typical case, the drive system may comprise a head roller shaft assembly and a tail roller shaft assembly each comprising at least one laterally extending roller shaft and a transmission means therearound defining the closed-loop continuous path. At least one of the roller shaft assemblies is provided with a rotary drive operable to cause the shaft assembly to rotate and thereby the transmission means to be driven about the closed-loop continuous path. The transmission means engages with the plurality of plates to cause the plate conveyor surface to be driven about the closed-loop continuous path.

Preferably the drive is a variable speed hydraulic/electro-mechanical drive.

Preferably the transmission means comprises a chain or belt.

Preferably the mineral conveyor comprises first and second spaced transmission drivers mounted on a head roller shaft and first and second spaced transmission drivers mounted on a tail roller shaft and first and second transmission means coupling corresponding head and tail transmission drivers.

Suitably each one of the plurality of plates is attached to the first and second transmission means and extends therebetween to provide the conveyor surface.

In operation, the drive means rotatably drives the head and/or tail shaft and corresponding transmission means mounted thereon to move the transmission means and plates attached thereto around a closed-loop continuous path.

Preferably the transmission means comprises a chain and the conveyor drive system comprises two spaced head sprockets mounted on a head roller shaft and two spaced tail sprockets mounted on the tail shaft and first and second transmission means coupling corresponding head and tail sprockets. Preferably the chain drive is of a sealed and lubricated hardened steel construction.

Preferably the sprockets on the head and tail shafts are a bolt-on segmented design made of a wear resistant alloy steel. Sprocket tooth segments are preferably interchangeable for easy maintenance. In a preferred design, each sprocket has an odd number of teeth on each wheel, such that contact with all of the teeth is only completed after two revolutions of the chain for a longer service life. The sprocket tooth segments are bolted onto hubs with high tensile bolts for ease of replacement. The plurality of plates provide an upper conveyor surface for conveying material and lower and curved end conveyor portions completing the continuous loop. The plates are moved around the closed-loop

continuous path. The plurality of plates may suitably be attached to the transmission means by bolts, for example. A plate is, for example, fabricated from rolled section steel to a width determined by the desired operational mode, for example of from 1 to 5 m, and to a thickness correspondingly determined by likely loading conditions.

A further aspect of the present invention provides an apron plate feeder comprising a mineral conveyor as described above. A further aspect of the present invention provides a mineral processing assembly comprising:

- a hopper to receive excavated mineral and discharge the same onto a receiving end of an apron plate feeder comprising a mineral conveyor as described above; and

- a mineral sizer or other crushing device to receive and process mineral from a discharge end of the apron plate feeder. Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which:

- Figures 1 to 4 show a known mineral conveyor;

- Figure 5 shows the build-up of trapped material at the input end of a mineral conveyor in accordance with the present invention;

- Figures 6 and 7 show a moveable plate in an open and closed

position when in the lower and upper conveyor portions

respectively;

- Figures 8a to 8d show a moveable plate and an adjacent plate as they move from the lower conveyor portion to an input end portion of a preferred embodiment of the conveyor;

- Figure 9 shows a cross section through a moveable plate and an adjacent plate of the conveyor of Figure 8;

- Figure 10 shows the adjacent plate of Figure 9;

- Figure 1 shows the moveable plate of Figure 9;

- Figure 12 shows a material discharge end of the inclined conveyor of Figure 8; and

- Figure 13 shows a guard for the discharge end of Figure 12.

As shown in Figures 5 to 7, a mineral conveyor 30 includes a plurality of plates 32 which provide a conveyor surface for material to be deposited and conveyed on. The plates 32 are attached to a pair of spaced chains (not shown) by bolts. The chains couple a pair of head sprockets and a pair of tail sprockets which are mounted to a head shaft and tail shaft respectively. The head and tail shafts are mounted on a main frame and one or both of the shafts is driven to move the plates around a continuous closed-loop path, as shown by arrows 41 , 43. The conveyor 30 has an upper portion 38 forming a top strand of a conveyor for conveying material and a lower portion 40 forming a bottom strand and end portions completing the continuous loop. The plates 32 move continuously around the loop during operation. Material deposited on the plates 32 in the upper portion 38 at an input end is conveyed towards a discharge end (not shown) in a direction indicated by arrow 41 .

During operation, fine material 45 slips between adjacent plates 32 and into the cavity 42 between the upper portion 38 and lower portion 40 of the conveyor 30. It is also known for material to enter the cavity 42 from a side of the main frame in the vicinity of the input end which is often surrounded by excavated material at the mine face when in use. As the mineral conveyor 30 is a closed-loop system, the material which has entered the cavity 42 between the upper and lower portions 38, 40 is trapped. Often the mineral conveyor 30 is elevated and due to the rotational direction and elevation thereof, the trapped material tends to collect and build up at the input end and might build up over time in a snowball effect. This undesirably adds weight to the conveyor and can obstruct the drive assembly at the input end of the conveyor.

Each of the plates 32 overlaps the adjacent plate in front of it relative to the direction of movement of the conveyor 30. At least one of the plates 44 is pivotally attached to a leading adjacent plate to be moveable from a closed position to an open position. Gravity and the overlap ensure the moveable plate 44 remains in the closed position when in the continuous upper portion 38 of the conveyor 30. When the moveable plate 44 enters an end portion and subsequently the lower portion 40 of the conveyor, the force of gravity moves the moveable plate 44 into the open position to define an opening in the otherwise continuous conveyor surface. Gravity returns the moveable plate 44 to the closed position on entry into the upper portion 38. The continuous opening and closing of the moveable plate 44 continues during operation of the conveyor 30.

Where continuous opening and closing of the moveable plate 44 is not required and selective opening and closing is preferred, it is envisaged that other actuation means and/or locking means may be used to open and/or close the moveable plate 44. Such actuation and/or locking means may include mechanical, electric and/or electromechanical actuation means. Such means may be required where, for example, the material being deposited on the conveyor is relatively muddy or sticky and the moveable plate is held in the closed position by such material when in the lower portion of the conveyor and gravity alone is insufficient to move the moveable plate to the open position.

The opening provided by the moveable plate 44 when in the open position allows material which is trapped in the cavity 42 to exit the conveyor as indicated by arrow 47. Manual interaction is desirably not required and costly downtime of the mineral conveyor and other associated mining equipment to remove the trapped material is desirably avoided.

A preferred embodiment of the present invention is shown in Figures 8 to 13. As shown in Figures 8a to 8d, a plurality of plates are bolted at their ends to a pair of spaced chains 54. The plates are moved around the continuous path of the closed loop conveyor by a rotary drive coupled to one or both of the chain sprockets 55.

As shown in Figure 9, each of the plurality of plates comprise an elongate ridged base 57 having end flanges 58 to form a conveyor wall for containing conveyed material when in the upper portion of the conveyor. The plates overlap each other at their base edges 56, 59 to form a continuous conveyor surface for conveying material when in the upper portion of the conveyor. The base edges 56, 59 are complementarily shaped thereby to provide a neat overlap and a continuous conveyor surface. As the plates are moved around the curved end portions of the conveyor in the vicinity of head and tail drive assemblies, the plates are forced apart as a result of the curved path and the overlap is reduced. A pair of plates 50, 52 are shown in Figure 9 moving along the lower conveyor portion in a direction indicated by arrow A. The leading adjacent plate 50 is bolted to the chains 54 while the trailing plate 52 is pivotally mounted to the adjacent plate 50 and is a moveable plate 52 relative to the fixed adjacent plate 50.

The plates 50, 52 are shown respectively in Figures 10 and 1 1 . Each plate 50, 52 has a spaced pair of lugs 62, 64 which extend from its base at or near opposing ends. The lugs 62, 64 engage the corresponding lugs of the other plate. Each pair of lugs 62, 64 has an aperture 66 through which first and second pins 60 engage to hingedly couple the plates 50, 52 together at their ends.

The first and second pins 60 share the same axis as a link pin of the chain 54 of the conveyor drive system when the plates 50, 52 form part of the continuous upper or lower conveyor portions. When the plates 50, 52 enter a curved end portion of the conveyor, the pin axis is forced outwardly from the link pin axis as a result of the pivotal arrangement of the plates. This desirably allows for a greater opening of the moveable plate 50. The base edges 56, 59 of neighbouring plates overlap which prevents the moveable plate 50 from pivoting downwardly when moving along the continuous lower portion of the conveyor, as shown.

However, the moveable plate 52 has a reduced trailing base edge 56 compared to other plates so that as the pair of plates 50, 52 move from the flat lower portion of the conveyor into the curved end portion, the overlap between the trailing base edge of the moveable plate 52 and the leading base edge of a neighbouring plate (not shown) is lost and plate 52 becomes unsupported at its trailing base edge 56. This moveable plate 52 is thereby allowed to pivot about pins 60 and move towards an open position.

The movement is a maximum when the moveable plate 52 is

approximately at the lowest point of the inclined conveyor, such as in the vicinity of a tail drive assembly, as shown in Figure 8d. Advantageously, this is where the build up of material in the cavity of the inclined conveyor will collect. As the moveable plate 52 opens, the collected material can escape through the opening to exit the conveyor cavity. As the moveable plate 52 will always be open at this point during every cycle of the conveyor, a build up of material is desirably prevented.

The inclined discharge end of the conveyor is shown in Figure 12. The pair of plates 50, 52 are shown at two different positions around the curved conveyor end portion. As shown, the moveable plate 52 also moves to the open position when moving around the curved end portion towards the lower portion of the conveyor at the inclined discharge end. However, this may be undesirable because material falling from the conveyor surface into a mineral sizer, for example, may fall through the opening and into the cavity of the conveyor. Material may also be thrown up from the mineral sizer through the opening. To prevent the moveable plate 52 opening at the discharge end of the conveyor, a guard 70 may be provided which effectively contains the plates 50, 52. The guard 70 is suitably spaced from the curved discharge end of the conveyor to prevent interference between the plates whilst preventing the ingress of material. The guard 70 may suitably comprise cleaning means, such as a brush or scraper, to remove material from the plates and/or prevent material ingress between the guard and the plates.

Claims

1 . A mineral conveyor comprising:

A mineral conveyor according to claim 1 , wherein the moveable plate is adapted to move from the closed position to the open position when positioned to form part of a lower portion and/or an end portion of the conveyor.

A mineral conveyor according to claim 1 or 2, wherein the moveable plate is adapted to move from the open position to the closed position when positioned to form at least part of an upper portion of the conveyor.

A mineral conveyor according to any preceding claim, wherein the moveable plate is adapted to move between the closed position and the open position by action of gravity.

A mineral conveyor according to claim 4, wherein retaining means are provided to tend to retain the moveable plate in the closed position against the action of gravity.

A mineral conveyor according to claim 5 wherein the retaining means comprise locking means activatable to selectively prevent the moveable plate from moving to the open position when undesirable and deactivated when desirable for the moveable plate to move to the open position.

A mineral conveyor according to any preceding claim comprising actuation means to apply an opening and/or closing force to be applied to the moveable plate to cause the plate to be selectively moved between the closed position and the open position and vice versa.

8. A mineral conveyor according to claim 7, wherein the actuation

means comprises electromagnetic actuation means.

9. A mineral conveyor according to claim 7 or 8, wherein the actuation means comprises mechanical actuation means.

10. A mineral conveyor according to any preceding claim, wherein the moveable plate is adapted to be self-actuating.

1 1 . A mineral conveyor according to claim 10, wherein a pivotal

arrangement between the moveable plate and an adjacent plate provides the self-actuation.

12. A mineral conveyor according to claim 1 1 , wherein the moveable plate trails the adjacent plate relative to a direction of movement of the conveyor.

13. A mineral conveyor according to claim 12, wherein the moveable plate is pivotally attached to the adjacent plate.

14. A mineral conveyor according to any of claims 1 1 to 13, wherein a trailing edge of the moveable plate is overlapped by a leading edge of a neighbouring plate trailing the moveable plate.

15. A mineral conveyor according to claim 14, wherein the trailing edge of the moveable plate is adapted to disengage with the leading edge of the neighbouring plate when positioned to form part of a curved end conveyor portion thereby to move to the open position.

16. A mineral conveyor according to any preceding claim comprising a plurality of equally spaced moveable plates.

17. A mineral conveyor according to any preceding claim wherein the conveyor drive system comprises:

- a head roller shaft assembly and a tail roller shaft assembly each comprising at least one laterally extending roller shaft, and

a transmission means therearound defining the closed-loop continuous path;

- at least one of the roller shaft assemblies being provided with a rotary drive operable to cause the shaft assembly to rotate and thereby the transmission means to be driven about the closed-loop continuous path; and

- the transmission means being engaged with the plurality of plates to cause the plate conveyor surface to be driven about the closed-loop continuous path. A mineral conveyor according to claim 17, wherein the mineral conveyor comprises first and second spaced transmission drivers mounted on a head roller shaft and first and second spaced transmission drivers mounted on a tail roller shaft and first and second transmission means coupling corresponding head and tail transmission drivers.

A mineral conveyor according to claim 18, wherein the transmission means comprises a chain and the conveyor comprises two spaced head sprockets mounted on a head roller shaft and two spaced tail sprockets mounted on the tail shaft and first and second transmission means coupling corresponding head and tail sprockets.

A mineral conveyor according to claim 18 or 19 wherein the plurality of plates are each attached to the first and second transmission means and extend therebetween to provide the conveyor surface.

An apron plate feeder comprising a mineral conveyor according to any preceding claim.

A mineral processing assembly including a hopper to receive excavated mineral and discharge the same onto a receiving end of an apron plate feeder comprising a mineral conveyor according to any preceding claim and a mineral sizer or other crushing device to receive and process mineral from a discharge end of the apron plate feeder.