WO2006007661A1

WO2006007661A1 - A wear plate fastening arrangement

Info

Publication number: WO2006007661A1
Application number: PCT/AU2005/001079
Authority: WO
Inventors: Peter Hale; Graham Strauss
Original assignee: Crushing & Mining Equipment Pty Ltd
Priority date: 2004-07-22
Filing date: 2005-07-22
Publication date: 2006-01-26

Abstract

A fastening arrangement for fastening a wear plate (100) in an impelling rotor (30) of a rotating shaft impactor is shown. The fastening arrangement comprises an arrangement of one or more interfitting projections and recesses. One of the projection (40) or recess (42) in each interfitting projection (40) and recess (42) is disposed on the wear plate (100), and the other of the corresponding projection (40) or recess (42) is disposed on one of the side wall (23) or the end plate (16, 18) of the impelling rotor (30).

Description

A WEAR PLATE FASTENING ARRANGEMENT

Field of the Invention

The present invention relates to the components of an impactor apparatus for breaking feed materials passed thereinto. In one form the invention relates to a fastening arrangement for fastening a wear plate for use in a rotating shaft impactor, and will primarily be described with reference to this context.

Background Art

Impactors for breakage of materials are known in the art. Such apparatus includes a rotating chamber arranged to rapidly rotate about an axis. Feed materials such as rock, gravel, mineral ores and the like are passed into the rotor chamber via an inlet and contact a distributor plate located on one side of the chamber opposite to the feed material inlet. The materials are thus slowed from a finite to a nil axial velocity. The materials then slide across the distributor plate with a finite radial velocity and are ejected sideways off the distributor plate and over various elements and out of the chamber, to impact against the surrounding walls of the impactor (which are sometimes fitted with anvils or other fixtures) , and thereby are attritioned.

An example of a known arrangement of an impactor is shown in Figures 1, IB and 1C. In this arrangement, a rotor is shown in a vertical axial orientation, and is gravity fed. A floor 18 of the rotor chamber is generally made of an ordinary quality fabricating steel. This floor 18 is protected against abrasive wear, caused by the flow of materials for breakage, by various shapes of cast alloy steel wear plates located thereon, as well as the distributor plate itself. Referring to the part numbers used in Figures 1, IB and 1C, a wear plate shown as 100 is seated on the chamber end plate (the lower end or floor 18 in the vertical shaft impactor arrangement shown) and is wedged and/or pegged into position between the distributor plate 10 and the exit portal 25, which is located in a side wall of the rotor chamber 12. In plan view as shown in Figure IB, the wear plate 100 is generally sub- triangular or trapezoidal in shape, the shape being determined by the adjacent parts and fitments. There is usually one such wear plate associated with each of the roof and floor of the rotor chamber at each of the exit portals 25, although in some arrangements there can be two or more wear plates in mutual abutment used to protect the rotor end plate. In some embodiments known in the art, an annular ring 200 of a cast material can be positioned between this wear plate 100 and the distributor plate 10, and one such example is shown in Figures 1 and IB. The ring 200 encircles the distributor plate 10 and generally abuts or is spaced a small distance from each of the wear plates 100. In use, material is ejected from the chamber 12 by respectively sliding over the distributor plate 10, the annular ring 200 and the wear plate 100 before passing out through the ejection portal 25. In some other known embodiments, there is no annular ring 200.

Due to the nature of the feed materials and the duty required of the apparatus, the distribution plate, annular ring and wear plates are subject to significant and uneven wear from the impact and sliding movement of the feed material. The distributor plate 10 (or at least its surface which is exposed to the feed material flow) can be made of a high strength metal such as tungsten carbide. Because of their unusual shape, the wear plates 100 are typically made of a wear resistant cast alloy steel. Even so, the wear plates can develop very marked wear in a short time necessitating relatively frequent replacement when compared with other parts used in the rotor. In order to change the wear plates it is usually necessary to firstly remove the distributor plate 10, and then to slide the wear plates 100, IOOA into position.

When preparing the rotor for use, typically the wear plate 100 shown in Figures 1 and IB is the first item to be placed on the chamber floor 18. The like wear plate IOOA is also placed on the chamber roof 16. Each of these wear plates is located by sliding into position in a radial direction outward from the centreline of the rotor, to be fixed for use near to a respective exit portal 25 located in a side wall of the rotor chamber 12. The wear plate is usually retained in this position (to avoid dislodgement) by side wall flanges or shoulders referred to as wear plate clips 52, 52B that are formed from, or welded or otherwise fastened to the floor (and roof) of the chamber and/or to the chamber side wall . Examples of these wear plate clips are shown in Figures IB and 1C.

When each wear plate 100, IOOA is retained in position at the respective floor or roof of the chamber, then, if present, an annular ring 200 of a cast material is lowered into the chamber 12 in a position to abut each of the wear plates 100. Finally, (with or without the presence of an annular ring 200) a distributor plate 10 is lowered into the chamber into the centre of the annular ring 200. The adjacent positioning of all of these components helps to retain their respective locations at the chamber end. When it is required to remove the worn wear plates 100, IOOA for replacement, a reverse order procedure is followed, with the wear plates being the last item to be removed. Because of the exposed nature of the side wall or end plate mounted clips 52, 52B which are above the surface of the wear plate facing the interior of the rotor chamber, these flanges or clips can become significantly worn by the flow of material across the wear plate. Clips that are located at the side wall of the chamber and positioned above the wear plate can even break off with impact from feed material. In the situation where a side edge or edge shoulder of the wear plate 100, IOOA is held in position by a retaining clip 52, 52B that is itself formed from, welded to, or pinned to the chamber wall or end plate, to the extent where it intrudes into the flow of material passing through the chamber, the clip itself may need to be hard-faced (or similarly prepared to resist wear) otherwise it can quickly become worn and fail. If failure occurs, the wear plate can break free and become dislodged. Any additional hard-facing or surface preparation of the clip can add to the cost and complication of the apparatus. Frequent replacement of components including wear plates and associated wear clips due to frictional wear or breakage first involves stopping the impactor and repairing, or manually removing and replacing, the various parts. This can be an awkward and difficult procedure, leading to significant down time of the impactor. A high frequency of maintenance shutdown can be very costly from an operational standpoint.

Summary of the Invention In a first aspect the present invention provides a fastening arrangement for fastening a wear plate in an impelling rotor of a rotating shaft impactor, the impelling rotor comprising a chamber defined by a side wall and an end plate, the end plate arranged substantially orthogonally and connected to the side wall of the chamber, the chamber arranged in use to rotate about an axis and to radially eject material received therein through one or more ejection ports in the side wall, and where the wear plate is arranged to be seated at the end plate, wherein the fastening arrangement comprises an arrangement of one or more interfitting projections and recesses, one of the projection or recess in each interfitting projection and recess being disposed on the wear plate, and the other of the corresponding projection or recess is disposed on one of the side wall or the end plate.

Being able to conceal the fastening arrangement^" from the material fed into the chamber during use can prevent abrasive wear or breakage of the fastening arrangement, and reduce the risk of the wear plate becoming dislodged in use. This can in turn reduces the down time of the impactor and attendant losses in operating revenue.

In one embodiment, at least one of the projections can be disposed on the wear plate and the corresponding recess can be located in the side wall. In other embodiments the reverse arrangement can also be the case.

In one embodiment, the wear plate incorporates opposite major surfaces and an edge surface that extends between said major surfaces. In this case the projection can be in the form of a tongue that extends from said edge surface. In one form of this, the tongue may extend from the edge surface at or adjacent one of the major surfaces, so as to be located in a corner region of the wear plate. In one embodiment, the or each recess that is located in the side wall can be a through-hole located in that side wall.

In one embodiment, at least one of the projections can be disposed on the wear plate and the corresponding recess can be located in the end plate of the chamber. In one form of this, the wear plate can incorporate opposite major surfaces and an edge surface that extends between said major surfaces and wherein the projection is in the form of a leg that extends from the major surface which is located in abutment with the end plate of the chamber.

In one embodiment, when the or each projection is received in a respective recess, it can be disposed substantially wholly therewithin so as to substantially prevent contact with material that is received in the chamber in use. In other embodiments this need not be the case, and the projection can be just partially recessed so as to reduce contact with material in the chamber without preventing contact. In other embodiments there may be another separate member which in use assists the concealment of the fastening arrangement.

In further embodiments the projection can be one of the group comprising a ridge, flange, tab, tongue, key, lump, knob, leg, rib or a pin, and the recess can be one of the group comprising a concavity, depression, slot, groove and a dent.

In an embodiment, at least one of the projections can be disposed on the wear plate and extend through the side wall, and wherein that projection is held in position by a coupler which is located outside the side wall of the chamber and couplable with a part of that projection which protrudes outside the side wall of the chamber. In one form of this, the part of the projection protruding outside the side wall can include a hole and the coupler can be a pin or a screw receivable in use in a flange arranged on the side wall and in the hole in the projection.

In one embodiment, the wear plate may be generally in the form of an irregular quadrilateral or trapezoidal plate, although other shapes may be required depending on the particular rotor shape and configuration. Typically the wear plate can be made of a wear resistant material, such as a hardened alloy steel and the like. The projection can also be made of a wear resistant material.

In one embodiment, the or each projection on the wear plate, side wall or end plate can be integral therewith, this is, formed of the same unitary mass. In an alternative form, the or each projection on the wear plate, side wall or end plate can be cast, welded or otherwise formed integral therewith in a separate process.

In a second aspect the present invention provides a fastening arrangement for fastening of a wear plate in an impelling rotor of a rotating shaft impactor, the impelling rotor comprising a chamber defined by a side wall and an end plate, the end plate arranged substantially orthogonally and connected to the side wall of the chamber, the chamber arranged in use to rotate about an axis and to radially eject material received therein through one or more ejection ports in the side wall, and where the wear plate is arranged to be seated at the end plate, wherein the fastening arrangement comprises at least one removable fastener receivable in a recess formed in the wear plate, the recess opening to the interior of the chamber, and the fastener being locatable through an aperture in the side wall so as to be at least partially recessed in the wear plate, in use so as to reduce contact between the fastener and material that is received in the chamber. By having a fastener that is removable from the wear plate, if the fastener becomes broken or worn, it can be readily replaced. This represents an advantage over prior art items such as wear plate clips the replacement of which, when worn or broken, can be complicated, time consuming and awkward. With a removable, partially- recessed fastener, it may not be necessary for the rotor chamber components (distributor plate, annular ring and wear plate) to require removal from the rotor chamber in order to replace the wear plate fastener if it becomes worn or broken.

In one embodiment, the wear plate incorporates opposite major surfaces and an edge surface that extends between said major surfaces and wherein at least part of the edge surface abuts the side wall of the chamber. In other forms, all of the edge surface may abut the side wall. In other arrangements, the side face of the wear plate need not touch the side wall and there may be a gap therebetween, or another separate member which in use partially conceals the fastener.

In one form of this, the recess can be located in the edge surface of the wear plate at or adjacent where the wear plate abuts the side wall of the chamber.

In some embodiments, the fastener can be one of the group comprising a pin, wedge, key, screw, bolt and a dowel. In alternative arrangements, the fastener can be a plate-like tongue and the recess can be a correspondingly-shaped shoulder or slot for receipt thereof.

In some embodiments of these, the fastener can be fastened in position by being threadingly engaged with the aperture in the side wall of the chamber.

In some embodiments, the fastener may be fully recessed into the wear plate and does not sit proud of the recess. Such an arrangement can conceal substantially all except an uppermost portion of the fastener from the material fed into the chamber in use, thus reducing abrasive wear or the risk of breakage of the fastener. In other embodiments this is not necessarily the case, and the member can protrude from the recess and be in some contact with material that is received into the rotor chamber in use. In such an arrangement, when the fastener becomes too badly worn, the removable fastener can be readily- withdrawn from being directly coupled with the wear plate and replaced.

In some embodiments of this aspect, the fastener can be held in position by a coupler as defined in the first aspect, and have the wear resistant properties of the projection as defined in the first aspect. In a third aspect the present invention provides a wear plate for a rotating shaft impactor having opposite major surfaces and an edge surface that extends between said major surfaces, wherein the wear plate further comprises at least one projection that forms part of an arrangement of interfitting projections and recesses that fastens the wear plate in an impelling rotor.

In one embodiment, the projection can be in the form of a tongue that extends from one of the edge surface or a major surface. In a fourth aspect the present invention provides a wear plate for a rotating shaft impactor having opposite major surfaces and an edge surface that extends between said major surfaces, wherein the wear plate further comprises at least one of a recess which is open to one of the major surfaces and that is adapted for at least partial receipt of a removable fastener in use to fasten the wear plate in an impelling rotor.

In a fifth aspect the present invention provides a wear plate for a rotating shaft impactor adapted for use with the interfitting projections or recesses as defined in the first aspect, or with the removable fastener as defined in the second aspect.

In a sixth aspect the present invention provides an impelling rotor of a rotating shaft impactor adapted for use with the interfitting projections or recesses as defined in the first aspect, or with the removable fastener as defined in the second aspect.

In a seventh aspect the present invention provides an impelling rotor of a rotating shaft impactor including the wear plate as defined in any one of the fourth, fifth or sixth aspects.

In an eighth aspect the present invention provides a rotating shaft impactor adapted for use with the interfitting projections or recesses as defined in the first aspect, or with the removable fastener as defined in the second aspect.

In a ninth aspect the present invention provides a rotating shaft impactor including the wear plate the wear plate as defined in any one of the fourth, fifth or sixth aspects.

Brief Description of the Drawings

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a side sectional view of a prior art wear plate fitted to an impelling rotor when assembled in a vertical shaft impactor machine;

Figure IB shows a plan view of the rotor portion of a vertical shaft impactor machine of Figure 1;

Figure 1C shows a side sectional view of the embodiment of Figure IB when shown along the line lC-lC,- Figure 2 shows a perspective, part-sectional view of one embodiment of an impelling rotor for a vertical shaft impactor, the impelling rotor having wear plates fastened to a top and bottom end plate thereof, in accordance with the invention; Figure 3 shows a side sectional view of the embodiment of Figure 2 when shown along the lines 2-2. In particular this Figure shows a wear plate fastened to each of a top and bottom end plate of an impelling rotor and a fastening arrangement for fastening each of the wear plates in the impelling rotor;

Figure 4 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine, in accordance with the invention;

Figure 4A shows a side sectional view of the embodiment of Figure 4 when shown along the line 4-4.

Figure 4B shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine, in accordance with the invention;

Figure 4C shows a side sectional view of the embodiment of Figure 4B when shown along the line 4C-4C.

Figure 4D shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine, in accordance with the invention;

Figure 4E shows a side sectional view of the embodiment of Figure 4D when shown along the line 4E-4E; Figure 5 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 5A shows a side sectional view of the embodiment of Figure 5 when shown along the line 5-5;

Figure 6 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention; Figure 6A shows a side sectional view of the embodiment of Figure 6 when _,shown along the line 6-6;

Figure 7 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention.

Figure 7A shows a side sectional view of the embodiment of Figure 7 when shown along the line 7-7.

Figure 8 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 8A shows a side sectional view of the embodiment of Figure 8 when shown along the line 8-8; Figure 9 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 9A shows a side sectional view of the embodiment of Figure 9 when shown along the line 9-9;

Figure 10 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention; Figure 1OA shows a side sectional view of the embodiment of Figure 10 when shown along the line 10-10;

Figure 11 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure HA shows a side sectional view of the embodiment of Figure 11 when shown along the line 11-11;

Figure 12 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 13 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 14 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 15 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention; Figure 15A shows a sectional view of the embodiment of Figure 15 when shown along the line 15A-15A;

Figure 15B shows a side sectional view of the embodiment of Figure 15 when shown along the line 15B-15B;

Figure 16 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 17 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 18 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 19 shows a side sectional view of one embodiment of a fastener for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention. Figure 20 shows a side sectional view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention; Figure 21 shows a plan view of one embodiment of a fastening arrangement for fastening of a wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 2IB shows a side sectional view of the embodiment of Figure 21 when shown along the line 2IB-2IB;

Figure 22 shows a side sectional view of one embodiment of a wear plate and a fastening arrangement for fastening of the wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention. In particular this Figure shows a wear plate fastened to a top end of an impelling rotor;

Figure 23 shows a side sectional view of one embodiment of a wear plate and a fastening arrangement for fastening of the wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention. In particular this Figure shows a wear plate fastened to a top end of an impelling rotor;

Figure 24 shows a plan view of one embodiment of a partial wear plate and a fastening arrangement for fastening of the wear plate in an impelling rotor of a vertical shaft impactor machine in accordance with the invention;

Figure 24A shows a side sectional view of the embodiment of Figure 24 when shown along the line 24A-24A; Figure 25 shows a side sectional view of one embodiment of a wear plate for use in an impelling rotor of a vertical shaft impactor machine, the wear plate configured in accordance with the invention. Modes for Carrying out the Invention

Referring to the prior art arrangement shown in Figures 1, IB and 1C, an impelling rotor 30 located in a vertical shaft impactor 14 is shown. The impelling rotor is a chamber 12 having a circular top end plate 16 and a bottom end plate 18, with several support posts 20 and wall sections 23 located near the circumference of the plates 16, 18. The posts 20 and walls sections 23 join the top end plate 16 to the bottom end plate 18 and space the plates 16, 18 apart. The rotor 30 is arranged to rotate about a vertical axis A-A. The posts 20 and walls sections 23 comprise discrete wall portions, the space between these wall portions defining portals 25 in the side wall of the chamber. In the embodiment shown, there are three such portals 25 arranged around the rotor chamber wall. In further embodiments the posts and wall sections can form wall portions of any shape or size dimension, and any number of portals.

In the embodiment shown, feed materials for breakage are gravity-fed into the rotating chamber 12 via an entry port 22 located in the upper end plate 16. Typical feed materials include rock, gravel, mineral ores, metalliferous slags, glass and the like. These relatively coarse materials pass into the rotor chamber 12 and strike the rotating distributor plate 10 which is located at the base of the rotor chamber 12. The feed materials slide across the distributor plate 10 and are ejected radially out from the rotor chamber 12 and through each of the portals 25, under centrifugal force. The feed materials discharge at high speed and enter the surrounding impactor body, either impacting on and interacting with other rocks contained in a housing known as a ^xrock box' positioned for that purpose inside the impactor walls 24, or impact onto wall-mounted anvils 21, and are broken apart or attritioned.

In use, abrasive wear is experienced by the rotor floor wear plates 100, IOOA or the annular ring 200 (if this ring is present) , which are positioned to protect the rotor floor (lower end plate 18) and rotor roof (upper end plate 16) against abrasion. A wear plate 100 seated on the rotor floor is wedged or pinned into position in proximity to each exit portal 25. During exit from the chamber 12, feed material slides, respectively, across the distributor plate 10, the ring 200 and the rotor floor protective wear plate (s) 100. After some period of operation, replacement of the wear plates 100 or ring 200 is required. Some wear will also experienced by the protective wear plates IOOA located at the roof of the chamber 12 also positioned in proximity to each exit portal 25. This wear eventually also requires the replacement of these wear plates IOOA.

In order to avoid repetition and for ease of reference, components and features of equivalent parts similar to those identified already have been designated with an additional "A" , such as the wear plate IOOA.

The axis of rotation of the impelling rotor can be located on any angle from the vertical up to and including a horizontal axis, and so the terms "roof" and "floor", or "upper" and "lower" if used herein should be regarded as a guideline only. For example, the embodiment shown in Figures 2 and 3 has a vertical axis of rotation, but the invention is not so restricted. In any embodiment it is possible that the feed materials can be passed into contact with the distributor plate and wear plates by, for example, a pumping arrangement; the feed materials may therefore be suspended in a fluid, such as in a slurry, for example. Such a feeding arrangement may be more important in those embodiments where gravity-feeding of the apparatus alone is not feasible.

Figure 2 onward now refer to embodiments of the invention. It is to be noted that the component parts which are the same as those shown in the prior art Figures 1, IB and 1C are now referred to with the same part number. As shown in Figure 2, feed material enters the impelling rotor 30 in the direction of the arrow F and passes into the chamber 12. The wear plates 100, IOOA are respectively seated at each of the circular lower end plate 18 and upper end plate 16, and fastened into position as will now be described. The wear plates 100, IOOA have two opposing major surfaces in the form of a substantially planar upper surface and a substantially planar lower surface, these surfaces joined by a side edge surface. One of the opposing planar surfaces rests in use on the end plates 16, 18 of the rotor 30, and the other of the opposing planar surfaces of each wear plate forms a 'wear surface' , which is exposed in use to the flow of materials through the rotor chamber. In the embodiment shown, in plan view the wear plates 100, IOOA are of an irregular trapezoidal shape made to cover the upper end plate 16 and the lower end plate 18 of the rotor 30. The wear plate 100, IOOA protects the end plates 16, 18 from materials flowing through the rotor chamber 12, and thus any damage to the rotor body 30 itself. Typically the wear element is made of a wear resistant material such as cast alloy steel.

In other embodiments, each wear plate need not be in the form of a single wear plate, but can be made up of a number of planar pieces or segments of hardened material which are separately fastened into place and which generally form one planar surface. In still other embodiments, depending on the rotor shape and configuration, the wear plate can be of a shape other than the irregular trapezoidal version shown in the Figures, provided that the wear plate provides coverage for the upper end plate 16 and the lower end plate 18 of the rotor 30.

In Figure 2, the rotor 30 is arranged to rotate about a vertical axis A-A. The various post 20 and wall section 23 pairs are thus vertically oriented and are spaced apart by portals 25 in the side wall of the chamber, through which the feed material is ejected from the rotor 30 in the direction of the arrows J, K under centrifugal force. The feed material then enters the ^λrock box' housing and strikes other rocks, or strikes the impactor anvils 21 and is thus broken apart. The direction arrow K is a more typical trajectory than arrow J for material being discharged from the distributor plate 10 and across the wear plate 100. An intense inter-particle pressure zone can be created in the rotor, resulting in the arrow K trajectory. In use, most of the abrasive wear experienced by the rotor floor wear plate 100 occurs at or near the side of the wear plate closest to the wall section 23. For that reason, in some embodiments the wear plates can be made thicker on the side closest to the wall section 23, as will shortly be described in relation to the embodiment shown in Figures 2 and 3 and also in the embodiment shown in Figures 4D and 4E.

In the embodiment shown in Figures 2 and 3, the side of each wear plate 100, IOOA that is closest to the side wall 23 of the rotor chamber is held in position by a fastening arrangement of interfitting projection(s) from the wear plate 100, IOOA which are received in corresponding recess (es) in the form of a through-hole in the rotor wall. The fastening arrangement is concealed to substantially prevent contact between the fastener and material that is ejected from the chamber in use.

Referring to Figure 3, the fastening arrangement shown comprises an integral elongate tongue 40, 40A which extends from the side edge 44, 44A of the wear plate 100, 100A, the remainder of the side edge 44, 44A being in direct abutment with the wall section 23. The tongue 40, 40A is received in use into a respective mating elongate through-hole 42, 42A located in the wall section 23 of the rotor 30. In this embodiment the elongate tongue 40, 4OA is positioned in a tight frictional or interference fit within the receptive hole 42, 42A, although in further embodiments the tongue need not necessarily fill the hole or cavity, but can be loosely received. In other embodiments the tongue can be of other shapes, for example rounded rather than rectangular in cross-section.

In the embodiment shown, the opening to the hole 42, 42A is located in that part of the side edge 44, 44A of the wear plate 100, IOOA which is in direct abutment with the side wall section 23 of the chamber 12, so that when the tongue 40, 40A is received in the hole 42, 42A it is not visible from the outermost surface 46, 46A of the wear plates which face toward the interior of the chamber 12. In this embodiment, the concealment of the fastening arrangement from the material fed into the chamber 12 in use prevents the possibility of abrasive wear or breakage of the fastening arrangement in normal operating circumstances, thus reducing the risk of the wear plate 100, IOOA becoming dislodged in use. Figure 3 also shows an embodiment of a wear plate

100, IOOA which has a respective side portion 50, 5OA of tapered thickness (being tapered at the side portion which is closest to the centreline of rotation A-A of the chamber 12 in use, and furthest from the side wall section 23) . In use, the side portion 50, 5OA of each wear plate

100, IOOA is wedged underneath a wear plate retaining flange in the form of a clip 52, 52A that is itself welded to the respective rotor chamber floor or roof (a prior art arrangement) . In other embodiments, the wear plate clip can be of a different shape or can be replaced by another form of fastening device for holding the wear plate 100, IOOA in position, for example removable fasteners which are inserted into the wear plate via holes in the upper end plate 16 (roof) or the lower end plate 18 (floor) of the rotor 30. In still further embodiments there may be situations where no other fastener or wear plate clip is used or required to retain the wear plate.

Depending upon the depth of the hole 42, 42A below the outermost surface 46, 46A of the respective wear plate 100, IOOA (ie the surfaces which face into the chamber 12 in use) , it make take some considerable erosive wear of the wear plate 100, IOOA before the cavity 42, 42A and tongue 40, 4OA therein is exposed to the flow of material J, K. At this point, replacement of one or both of the wear plates 100, IOOA would be needed.

Various other embodiments of concealed wear plate fastening arrangements will now be separately described which make use of interfitting projection(s) from one of the wear plate or a portion of the rotor, for in use receipt in corresponding recess (es) in the other of the wear plate or a portion of the rotor. Each of these Figures show a view of an embodiment of a fastening arrangement used to fasten a wear plate to a rotor chamber wall, roof or floor. Any of the wear plate fastening arrangements shown can be used either alone or in combination with any of the other forms thereof that are described herein. Furthermore, if a wear plate fastening arrangement is shown for fastening a wear plate located at the floor of a rotor chamber, the same fastening arrangement can be envisaged for a wear plate located at the roof, or another location, of the rotor chamber.

In order to avoid repetition and for ease of reference, components and features of the following alternative embodiments which have a similar functionality to the embodiment shown in Figures 2 and 3 have been designated with an additional letter such as "B" or "C" etc, such as the "wear plate 10OB" . Referring now to Figures 4 and 4A, a concealed fastening arrangement is shown located between a wear plate and a rotor side wall. An integral elongate rectangular tongue 4OB extends from the side edge 44B of the wear plate 10OB, the remainder of the side edge 44B being in direct abutment with the side wall 23B. The tongue 40B is located at a position midway the depth of the wear plate IOOB and received in use into a respective mating elongate cavity or recess 42B that is located in the wall section 23B of the rotor 30. When the rectangular tongue 4OB is received in the recess 42B it is not visible from the outermost surface 46B of the wear plate IOOB which faces toward the interior of the rotor chamber 12.

Referring now to Figures 4B and 4C, a concealed fastening arrangement is shown located between a wear plate and a rotor side wall . An integral elongate rectangular tongue 40B2 extends from the side edge 44B2 of the wear plate 100B2, the remainder of the side edge 44B2 being in direct abutment with the side wall 23B2. The tongue 40B2 protrudes from the lowermost edge of the wear plate 100B2 and is received in use into a respective mating elongate cavity or recess 42B2 that is located in the wall section 23B2 of the rotor 30. When the rectangular tongue 40B2 is received in the recess 42B2 it is not visible from the outermost surface 46B2 of the wear plate 100B2 which faces toward the interior of the rotor chamber 12. The rectangular tongue 40B2 does not protrude outside of the exterior of the side wall 23B2 of the rotor chamber 12, but.is arranged flush therewith.

Referring now to Figures 4D and 4E, a concealed fastening arrangement is shown located between a wear plate and a rotor side wall . An integral elongate rectangular tongue 40B3 extends from the side edge 44B3 of the wear plate 100B3, the remainder of the side edge 44B3 being in direct abutment with the side wall 23B3. The tongue 40B3 protrudes from the uppermost region 81 of the wear plate 100B3, which is arranged to be of greatest depth -(in the region closest to the side wall 23B3) . This is so that material following an arrow K trajectory will take a longer operating time to erode this wear plate 100B3. The tongue 40B3 is received in use into a respective mating elongate cavity or recess 42B3 that is located in the wall section 23B3 of the rotor 30. When the rectangular tongue 40B3 is received in the recess 42B3 it is not visible from the outermost surface 46B3 of the wear plate 100B3 which faces toward the interior of the rotor chamber 12. For stability, the rectangular tongue 40B3 is arranged to protrude outside of the exterior of the side wall 23B3 of the rotor chamber 12, where external fasteners may be applied of the type shown in the forthcoming Figures 19 and 20.

Referring now to Figures 8 and 8A, a concealed fastening arrangement is shown in the form of a rounded protrusion 40D formed on the wall section 23D of the rotor which is received into a mating rounded dimple 42D formed in a wear plate 10OD. The side face 44D of the wear plate IOOD is in direct abutment with the wall section 23D. When the protrusion 4OD is received in the dimple 42D it is not visible from the outermost surface 46D of the wear plate 10OD which faces toward the interior of the rotor chamber 12.

Referring now to Figures 9 and 9A, a concealed fastening arrangement is shown in the form of a rounded dimple 42E formed in the wall section 23E of the rotor into which is received a mating rounded protrusion 40E formed on a wear plate 10OE. The side face 44E of the wear plate IOOE is in direct abutment with the wall section 23E. When the protrusion 42E is received in the dimple 40E it is not visible from the outermost surface 46E of the wear plate IOOE which faces toward the interior of the rotor chamber 12.

In further embodiments, the rounded protrusion and mating rounded dimple of Figures 8, 8A and 9 and 9A can be of other shapes and configurations. For example, referring now to Figures 10 and 1OA, a fastening arrangement is shown in the form of a rectangular elongate (pin-like) protrusion 40F formed on the wall section 23F of the rotor which is received in use into a mating elongate cavity 42F formed in a wear plate 10OF. The side face 44F of the wear plate 10OF is in direct abutment with the wall section 23F. When the elongate protrusion 40F is received in the cavity 42F it is not visible from the outermost surface 46F of the wear plate IOOF which faces toward the interior of the rotor chamber 12.

A further example of a different configuration of a fastening arrangement located between a wear plate and a rotor side wall is shown in Figures 11 and HA. A rectangular tongue or flange 40G which protrudes from the lowermost edge of the wear plate IOOG and is received in use into a mating rectangular cavity 42G located in the wall section 23G of the rotor 30. The remainder of the side face 44G of the wear plate IOOG is in direct abutment with the wall section 23G. When the rectangular flange

40G is received in the cavity 42G it is not visible from the outermost surface 46G of the wear plate 10OG which faces toward the interior of the rotor chamber 12, nor is it accessible from the outside of the exterior of the side wall 23G of the rotor chamber 12, but is concealed therewithin.

In other preferred embodiments, the wear plate can be arranged to be seated at an end plate of the rotor, and the wear plate fastening arrangement comprises an arrangement of interfitting projections and recesses located between the rotor end plate and the respective wear plate, as will now be described.

Referring now to Figures 13 and 14, the fasteners shown are not visible from that surface 46J, 46K of the wear plate which faces the interior of the rotor chamber 12. In Figure 13 a fastening arrangement is shown in the form of a rectangular flange or leg 40J which projects from a lowermost face of the wear plate 10OJ and which is received in a mating rectangular cavity 42J formed on the lower end plate 18J (floor) of the rotor 3OJ. When the flange 42J is received in the cavity 40J it is not visible from the outermost surface 46J of the wear plate 10OJ which faces toward the interior of the rotor chamber 12. A reverse arrangement of the embodiment shown in Figure 13 is given in Figure 14. In Figure 14 a first fastening arrangement is shown in the form of a rectangular flange or leg 40K which projects from the lower end plate 18K (floor) of the rotor 3OK and which is received in a mating rectangular cavity 42K formed in the wear plate 10OK. When the flange 40K is received in the cavity 42K it is not visible from the outermost surface 46K of the wear plate IOOK which faces toward the interior of the rotor chamber 12. In addition, the embodiment shown in Figure 14 illustrates a dual fastening arrangement. In addition to the aforementioned rectangular flange 40K and mating rectangular cavity 42K, a removable fastener is shown in the form of an elongate pin 74 having an enlarged head section 70. The elongate portion of the pin 74 is inserted through a hole 45K located in the wall section 23K of the rotor and is received into an open recess 72 located in the wear plate 10OK. When in position, the enlarged head section 70 is located in abutment with the wall section 23K outside of the rotor chamber. The side face 44K of the wear plate IOOK is also located in direct abutment with the wall section 23K on the inside of the rotor chamber. When the pin 74 is received in the cavity 72 it is recessed into the wear plate so as to reduce the in use contact between the pin 74 and the material moving past the outermost surface 46K of the wear plate IOOK which faces toward the interior of the rotor chamber 12.

In other embodiments, the wear plate can be held in position by any number of interfitting projections and recesses located between the end plates 16, 18 and the wear plate, or between the rotor side wall 23 and the wear plate. The projection(s) can be any type of discrete projecting ridge, flange, tab, tongue, key, lump, knob, leg, rib or pin, for example, that is formed or fitted so that when the wear plate is seated at the end plate 16, 18, the projection can act to engage or fasten the position of that wear plate in a corresponding receptive cavity in one of the wear plate, the rotor side wall or the end plate.

Further embodiments of dual fastening arrangements are shown in Figures 22 and 23 when arranged in the upper end plate 16 (roof) of the rotor 30. A rectangular flange 40V extending from the end plate 16V and a mating rectangular cavity 42V in the wear plate 10OV are shown in addition to a rectangular tongue or flange 40V2 which protrudes from the lowermost edge of the wear plate 10OV which is received in use into a mating rectangular cavity 42V2 located in the wall section 23V of the rotor 30. The remainder of the side face 44V of the wear plate 100V is in direct abutment with the wall section 23V on the inside of the rotor chamber.

In the embodiment shown in Figure 23, an elongate removable pin 4OW is inserted through a hole 45W located in the wall section 23W of the rotor and is received into an open recess 96 in the wear plate 10OW. However, in this embodiment a concealed fastener is shown in the form of a removable elongate pin 41W having an enlarged head section 95 and a threaded end tip. The elongate portion 98 of the body of the pin 41W is inserted through a hole 49W located in the upper end plate 16W of the rotor and the end tip is received into a mating, threaded elongate cavity 42W in a wear plate 10OW. When in position, the enlarged head section 96 is located in abutment with the upper end plate 16W at the outside of the rotor chamber 12. The side face 44W of the wear plate IOOW is also located in direct abutment with the wall section 23W on the inside of the rotor chamber. A further embodiment of a dual fastening arrangement is shown in Figure 12 in the form of a removable elongate pin 40H having an enlarged head section 76. The elongate portion 78 of the body of the pin 40H is inserted through a hole 45H located in the end plate 18H of the rotor and is received into a mating elongate cavity 42H in a wear plate 10OH. When in position, the enlarged head section 76 is located in abutment with the lower end plate 18H and outside of the rotor chamber 12. The side face 44H of the wear plate 10OH is also located in direct abutment with the wall section 23H on the inside of the rotor chamber.

The other features of the flange or tongue 40H extending from the wear plate 100V and into a mating through-hole 42H in the chamber side wall 23H are the same as previously described in other embodiments. In the embodiment shown in Figure 12, or in the other embodiments envisaged here, when the pin 4OH is received in the cavity 42H it is not visible from the outermost surface 46H of the wear plate 10OH which faces toward the interior of the rotor chamber 12.

Referring now to Figures 15, 15A and 15B, a fastening arrangement is shown in the form of two projecting legs each leg having a generally oval-shaped foot 40L, the legs and feet which project from a lowermost face of the wear plate IOOL and which are each receivable in a mating oval- shaped socket cavity 42L formed in the lower end plate 18L (floor) of the rotor 3OL. When the legs and feet 40L are received into the socket cavity 42L, the wear plate IOOL can be moved until the feet 4OL lock into place under a ledge 4IL in the socket cavity 42L. In this embodiment it is noted that the edge region 80 of the wear plate IOOL is arranged to be of greatest thickness in the region closest to the side wall 23L so that material following an arrow K trajectory will take a longer operating time to erode this wear plate region 80.

A fastener used in any of the embodiments of fastening arrangement referred to in this specification may be secured to the rotor wall section 23 or to the upper or lower end plates 16, 18 in a number of ways. In addition to frictional or interference type fittings, some further examples are presented in Figures 18 to 20. In each case, a removable fastener is shown in the form of a elongate pin 4OP, 40R, 4OS which is in use inserted through a respective hole 45P, 45R, 45S located in the respective wall section 23P, 23R, 23S of the rotor and is received into a respective recess 42P, 42R, 42S which is open to the interior of the rotor chamber and which is formed in the respective wear plate 10OP, 10OR, 10OS. In Figure 18, the pin 4OP is fastened in position by- being threadingly engaged with the hole 45P located in the wall section 23P of the rotor. A portion of an elongate stem' of the pin 4OP closest to the enlarged head of the pin is threaded, as is the circumference of the hole 45P. In Figures 19 and 20, the pin 40R, 40S is held in position by a coupler which is located outside of the side wall 23R, 23S of the rotor chamber and couplable with a part of the pin which protrudes outside of the side wall 23R, 23S of the rotor chamber. In Figure 19, the coupler is a pin 130 which passes through both a flange 132 formed on the side wall 23R, and via a hole 134 through the pin 40R. In Figure 20, the coupler is a partially threaded screw 136 which passes through a hole 138 in the pi,n 40S and is arranged so that the threaded portion of the screw 136 is received into a mating threaded cavity 140 in the lower end plate 18S of the rotor. There are many other examples of such fastening mechanisms, all of which are within the scope of the present invention.

In further embodiments shown in Figures 5 and 5A, Figures 6 and 6A, and in Figures 16 and 17, a fastening arrangement is shown in which a removable fastener is used for fastening of a wear plate in an impelling rotor where the fastener is only at least partially recessed in the wear plate, and/or is visible from the outermost surface of the wear plate which faces towards the interior of the rotor chamber. In such a recess, the fasteners shown have a reduced amount of contact with the feed material in the chamber in use, when compared with wear plate clips (eg 52, 52B) of the prior art. Referring now to Figures 7 and 7A, a fastening arrangement is shown in the form of an plate-like tongue 4OC that is removably insertable through a slot hole 45C located in the wall section 23C of the rotor and is received into an open recess 42C in a wear plate lOOC. The side face 44C of the wear plate IOOC is in abutment with the wall section 23C. When the tongue plate 4OC is received in the recess 42C it is visible from the outermost surface 46C of the wear plate IOOC which faces toward the interior of the rotor chamber 12.

Referring now to Figures 5 and 5A, a fastening arrangement is shown in which an elongate pin 40X is received through a hole 45X in the side wall 23X of the chamber and is also received into an open recess 42X located in the wear plate 10OX. The elongate pin 40X has an enlarged head section 104. The elongate portion 106 of the body of the pin 40X is received into a narrow open recess 42X which is of a width slightly larger than the width of the pin 40X, as shown in Figure 5. When in position, the enlarged head section 104 is located in abutment with the wall section 23X outside of the rotor chamber. The side face 44X of the wear plate IOOX (and the recess 42X) is also located in direct abutment with the wall section 23X on the inside of the rotor chamber. When the pin 4OX is received in the recess 42X it visible from the outermost surface 46X of the wear plate IOOX which faces toward the interior of the rotor chamber 12. In further embodiments, the pin can be of different shapes, or can be a plate-like tongue or wedge, and the recess can be a correspondingly-shaped shoulder or slot for receipt thereof.

Figures 6 and 6A depict a similar arrangement to that shown in Figures 5 and 5A, except that the fastening arrangement involves a fastener in the form of a plate- like portion 40Y also having an enlarged head region 130.

The plate-like portion 40Y is oriented vertically and is not fully enclosed in the open recess 42Y of the wear plate, 10OY. An uppermost portion of the plate 40Y sits proud of the open recess 42Y and is therefore exposed to the material fed into the chamber in use, and will experience some abrasive wear thereat. As the plate 40Y becomes worn, it may reach a point where the wear necessitates its removal and replacement, which can be readily accomplished with such a slidingly removable fastener.

In a further embodiment shown in Figure 16, a fastening arrangement is shown which uses a fastener in the form of a removable elongate pin 40M having an enlarged head section 114. The elongate portion 116 of the body of the pin 40M is inserted through a hole 45M located in the wall section 23M of the rotor and is received into a mating elongate cavity 42M in a wear plate 10OM. When in position, the enlarged head section 114 is located in abutment with the wall section 23M outside of the rotor chamber. The side face 44M of the wear plate IOOB is spaced apart from the wall section 23M on the inside of the rotor chamber. When the pin 40M is received in the cavity 42M it is visible from above the outermost surface 46M of the wear plate IOOM and the interior of the rotor chamber 12, and is therefore somewhat exposed to the material fed into the chamber in use.

In a further embodiment shown in Figure 17, which is in all other respects similar to that shown in Figure 16, the side face 44N of the wear plate IOON is spaced away from the opposing facing rotor side wall section 23N and the pin 40N is received in an open recess 42N in use. When the pin 4ON is received in the recess 42N it is visible from above the outermost surface 46N of the wear plate IOON and the interior of the rotor chamber 12 and is therefore exposed to the material fed into the chamber in use.

In a further embodiment shown in Figures 21 and 2IB, a fastening arrangement is shown in the form of a plurality of spaced-apart, removable fasteners that are positioned along one side of the wear plate 100XX. Each fastener comprises an elongate wedge 40XX which tapers over its length. The length of each wedge, and therefore the length to which each wedge 40XX extends across into the wear plate 100XX, is different. Each wedge 40XX is received through a hole 45XX in the side wall 23XX of the chamber, and is also received into a single, common open recess 42XX located along the edge region of the wear plate 100XX, a recess which has a perimeter which generally extends along the direction arrow K (the typical trajectory for material being discharged out of the rotor and across the wear plate 100XX, and along which most of the abrasive wear experienced by the rotor floor occurs) . When in position, the enlarged end section of each wedge is located so as to protrude beyond the wall section 23XX and outside of the rotor chamber, and is pinned thereat in the manner already described in relation to Figure 19. The side face 44XX of the wear plate IOOXX is located in direct abutment with the wall section 23XX on the inside of the rotor chamber. When each wedge 40XX is received in the common recess 42XX it sits proud of the outermost surface 46XX of the wear plate IOOXX and faces toward the interior of the rotor chamber 12. To improve the wear resistance of the wear plate it is envisaged that the wedges 40XX can be made of a wear resistant material, such as tungsten carbide.

It is noted that, in embodiments of a fastening arrangement located between a wear plate and a rotor side wall when an arrangement of interfitting projections and recesses is used, the shape of the projections or recesses is not necessarily regular in the sense of being rectangular or square, but can be many other shapes. The wear plate may have embodiments with various protruding flanges of more unusual shapes, or the wear plate itself may bear recesses for receipt of projections, and those recesses may be of unusual shapes.

For example, referring to Figures 24 and 24A, a plan view of a portion of a wear plate is shown as a further example of a different configuration of a fastening arrangement located between a wear plate and a rotor side wall. In this instance, a tongue or flange 40YY protrudes from one side wall of the wear plate 10OYY, and a further flange 40ZZ protrudes from the side wall of the wear plate 10OYY which faces inwardly into the rotor chamber. The flange 40YY is received in use into a mating rectangular cavity 42QQ located in the wall section 23QQ of the rotor, and the flange 40ZZ is received in use into a mating wear plate clip 52. In this example the leading edge 105 of each flange 40YY and 40ZZ is tapered to guide and facilitate withdrawal of the wear plate IOOYY when being removed from its installed position by sliding in the direction of the arrow A. In a further example, referring now to Figure 25, a side view is given of that side 44QQ of a wear plate 100QQ which faces onto the rotor chamber wall 23. In this case; the fastening arrangement located between the wear plate and a rotor side wall would be pins (or lugs or the like) received into the two downwardly tapering slot recesses 110 shown, or in the 'open' recesses 120 shown at the end corner regions of the wear plate side 44QQ.

The performance and maintenance requirements of rotating shaft impactors are affected by the cost of parts and how frequently these parts need to be changed.

Operating costs are also affected by how long it can take for these parts to be changed (ie. machine downtime) . In the embodiments described, the fastening arrangements which are used to fasten the wear plates in the rotor chamber are at least to some extent concealed from the flow of feed material through the rotor, thereby reducing wear on the particular types of fasteners used, and the need to frequently replace them. Fasteners that are removable from being coupled with the wear plate also have the advantage that if the fastener becomes broken or worn, it can be readily replaced without needing to remove the distributor plate, the annular ring or the wear plate from the rotor chamber in order to do so, thus reducing machine downtime. The inventors have shown that reduced frequency of servicing and maintenance intervals can be combined with safer and easier changing of impactor machine parts by using removable fasteners of the types described. Overall, such improvements can lead to lower materials processing costs.

The materials of construction of the wear plate and the fasteners described can be any suitable materials which wear appropriately, and that can be shaped, formed and fitted in the manner so described, such as the appropriate metal, metal alloys or ceramics etc. If the fastening arrangement is fully concealed from the material introduced into the rotor chamber in use, the fasteners used do not need to be especially hardened or be made of very strong materials and can be formed from lighter weight metals such as aluminium or hard plastics and the like.

It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms a part of the common general knowledge in the art, in Australia or any other country.

Whilst the invention has been ^• described with reference to preferred embodiments it should be appreciated that the invention can be embodied in many other forms.

Claims

1. A fastening arrangement for fastening a wear plate in an impelling rotor of a rotating shaft impactor, the impelling rotor comprising a chamber defined by a side wall and an end plate, the end plate arranged substantially orthogonally and connected to the side wall of the chamber, the chamber arranged in use to rotate about an axis and to radially eject material received therein through one or more ejection ports in the side wall, and where the wear plate is arranged to be seated at the end plate, wherein the fastening arrangement comprises an arrangement of one or more interfitting projections and recesses, one of the projection or recess in each interfitting projection and recess being disposed on the wear plate, and the other of the corresponding projection or recess is disposed on one of the side wall or the end plate.

2. A fastening arrangement as claimed in claim 1 wherein at least one of the projections is disposed on the wear plate and wherein the corresponding recess is located in the side wall.

3. A fastening arrangement as claimed in claim 2 wherein the wear plate incorporates opposite major surfaces and an edge surface that extends between said major surfaces and wherein the projection is in the form of a tongue that extends from said edge surface.

4. A fastening arrangement as claimed in claim 3 wherein the tongue extends from the edge surface at or adjacent one of the major surfaces.

5. A fastening arrangement as claimed in any one of claims 2 to 4 wherein the or each recess located in the side wall is a through-hole located in that side wall .

6. A fastening arrangement as claimed in any one of the preceding claims wherein at least one of the projections is disposed on the wear plate and wherein the corresponding recess is located in the end plate.

7. A fastening arrangement as claimed in claim 6 wherein the wear plate incorporates opposite major surfaces and an edge surface that extends between said major surfaces and wherein the projection is in the form of a leg that extends from the major surface which is located in abutment with the end plate of the chamber.

8. A fastening arrangement as claimed in any one of the preceding claims wherein, when the or each projection is received in a respective recess, it is disposed substantially wholly therewithin so as to substantially prevent contact with material that is received in the chamber in use.

9. A fastening arrangement as claimed in claim 1 or claim 2 wherein the projection is one of the group comprising a ridge, flange, tab, tongue, key, lump, knob, leg, rib or a pin, and the recess is one of the group comprising a concavity, depression, slot, groove and a dent.

10. A fastening arrangement as claimed in any one of the preceding claims wherein at least one of the projections is disposed on the wear plate and extends through the side wall, and wherein that projection is held in position by a coupler which is located outside the side wall of the chamber and couplable with a part of that projection which protrudes outside the side wall of the chamber.

11. A fastening arrangement as claimed in claim 10 wherein the part of the projection protruding outside the side wall includes a hole and the coupler is a pin or a screw receivable in use in a flange arranged on the side wall and in the hole in the projection.

12. A fastening arrangement as claimed in any one of the preceding claims wherein the wear plate is generally in the form of an irregular quadrilateral or trapezoidal plate.

13. A fastening arrangement as claimed in any one of the preceding claims wherein the wear plate and/or the projection is made of a wear resistant material.

14. A fastening arrangement as claimed in any one of the preceding claims wherein the or each projection on the wear plate, side wall or end plate is integral therewith.

15. A fastening arrangement as claimed in any one of claims 1 to 13 wherein the or each projection on the wear plate, side wall or end plate is cast, welded or otherwise formed integral therewith.

16. A fastening arrangement for fastening of a wear plate in an impelling rotor of a rotating shaft impactor, the impelling rotor comprising a chamber defined by a side wall and an end plate, the end plate arranged substantially orthogonally and connected to the side wall of the chamber, the chamber arranged in use to rotate about an axis and to radially eject material received therein through one or more ejection ports in the side wall, and where the wear plate is arranged to be seated at the end plate, wherein the fastening arrangement comprises at least one removable fastener receivable in a recess formed in the wear plate, the recess opening to the interior of the chamber, and the fastener being locatable through an aperture in the side wall so as to be at least partially recessed in the wear plate, in use so as to reduce contact between the fastener and material that is received in the chamber.

17. A fastening arrangement as claimed in claim 16 wherein the wear plate incorporates opposite major surfaces and an edge surface that extends between said major surfaces and wherein at least part of the edge surface abuts the side wall of the chamber.

18. A fastening arrangement as claimed in claim 17 wherein the recess is located in the edge surface of the wear plate at or adjacent where the wear plate abuts the side wall of the chamber.

19. A fastening arrangement as claimed in any one of claims 16 to 18 wherein the fastener is one of the group comprising a pin, wedge, key, screw, bolt and a dowel.

20. A fastening arrangement as claimed in any one of claims 16 to 18 wherein the fastener is a plate-like tongue and the recess is a correspondingly-shaped shoulder or slot for receipt thereof .

21. A fastening arrangement as claimed in any one of claims 16 to 18 wherein the fastener is fastened in position by being threadingly engaged with the aperture in the side wall of the chamber.

22. A fastening arrangement as claimed in any one of claims 16 to 21 wherein the fastener is fully recessed into the wear plate and does not sit proud of the recess.

23. A fastening arrangement as claimed in any one of claims 16 to 22 wherein the fastener is otherwise as defined for the projection of claims 10, 11 or 13.

24. A wear plate for a rotating shaft impactor having opposite major surfaces and an edge surface that extends between said major surfaces, wherein the wear plate further comprises at least one projection that forms part of an arrangement of interfitting projections and recesses that fastens the wear plate in an impelling rotor.

25. A wear plate as claimed in claim 24 wherein the projection is in the form of a tongue that extends from one of the edge surface or a major surface.

26. A wear plate for a rotating shaft impactor having opposite major surfaces and an edge surface that extends between said major surfaces, wherein the wear plate further comprises at least one of a recess which is open to one of the major surfaces and that is adapted for at least partial receipt of a removable fastener in use to fasten the wear plate in an impelling rotor.

27. A wear plate for a rotating shaft impactor adapted for use with the interfitting projections or recesses as defined in any one of claims 1 to 15 or the removable fastener as defined in any one of claims 16 to 23.

28. An impelling rotor of a rotating shaft impactor adapted for use with the interfitting projections or recesses as defined in any one of claims 1 to 15 or the removable fastener as defined in any one of claims 16 to 23.

29. An impelling rotor of a rotating shaft impactor including the wear plate as defined in any one of claims 24 to 27.

30. A rotating shaft impactor adapted for use with the interfitting projections or recesses as defined in any one of claims 1 to 15 or the removable fastener as defined in any one of claims 16 to 23.

31. A rotating shaft impactor including the wear plate as defined in any one of claims 24 to 27.