WO2000041812A1 - Apparatus and method for crushing reinforced concrete and the like - Google Patents

Abstract

Crushing apparatus in which a pivotally mounted first crushing member (24) is provided with a plurality of crushing regions (31, 32, 33, 34, 35) located at various distances from the pivot axis (25), which is offset, so that as the first crushing member is cyclically advanced towards and retracted from a second crushing member (14), successive crushing regions approach the second member closer than the preceding crushing region, to crush material (37) by a combination of compression and shear forces, and a transverse member (52) is provided in the crushing apparatus downstream of the throat (50), to divide the outflow of crushed fragments and hold up oversized material.

Description

APPARATUS AND METHOD FOR CRUSHING REINFORCED CONCRETE AND THE LIKE

This invention relates to an apparatus and method for crushing plain and reinforced concrete, rocks and the like.

Concrete is a hard material and very resistant to compression. It is relatively weak in tension, which is why for structural purposes concrete is often reinforced with steel wire or steel bars, to increase its resistance to tensile and bending forces.

In the demolition of concrete buildings and other structures, it is desirable to recover the concrete and crush it down to small pieces that can be re-used as aggregate in new concrete structures. If the original concrete contains steel reinforcement, it is necessary to separate the concrete from the steel. The steel itself can also be recycled as scrap for steel refining furnaces.

The fragmentation of reinforced concrete is, in the nature of things, not easy, because the concrete is specifically designed to be resistant to breakage. One possible method is to use jaw mechanisms on the articulated arm of an excavator or like machine, by means of which small pieces of concrete can be gradually removed from the internal steel skeleton. Normal rock or concrete crushers have a small jaw movement of, typically, 50-75mm, and can only accept concrete in short lengths. However, the internal steel bars or wire are relatively elastic, and the short movement cycle of the jaws is insufficient to compress the bar and wire to allow it to pass cleanly through the throat of these crushers to the conveyor below them which carries away the debris.

Consequently, the throat becomes obstructed with a tangle of steel reinforcement. Hydraulic chisels can also break this kind of concrete, but are not effective for cleaning concrete from the steel reinforcement.

My earlier patent specification EP-A-0 106 642 discloses an apparatus and method for fragmenting frangible objects, especially scrap metal, and in particular cast iron motor vehicle engine blocks and the like. The apparatus is also suitable for reducing the size of rock such as chalk after quarrying. The present invention concerns the use of a crusher mechanism that operates with many principles in common with the engine crusher described in EP-A-0 106 642, and the disclosure of that documents applies in general to the present invention, and is incorporated herein by reference, except where it is inconsistent with the description of the concrete crusher herein.

The basic crusher configuration of EP-A-0 106 642 may be adopted. This is a jaw mechanism in which a pivoted first crushing member which is provided with a plurality of crushing regions is cyclically advanced towards and retracted from a fixed second crushing member, the gap between the two crushing members forming a throat into which uncrushed materials can be placed from above and from which fragmented product falls through below.

It is a feature of the engine crusher design that the plurality of crushing regions on the first crushing member are located at various distances from the pivot axis, which is offset, so that successive crushing regions approach the second member closer than the preceding crushing region, fragmenting the object by a combination of compression and shear forces.

In this present invention, a similar arrangement is preferred, although it is presently envisaged that alternative pivot locations are possible, and a different distribution of distances of each crushing region from the pivot axis.

When the crusher is working, the first member alternately advances towards the second member, and retracts from the second member. When the first member advances, it crushes and shears material in the crusher and urges the fragmented product through the throat of the crusher and out of the apparatus. When the first member retracts, it opens the throat defined between the first and second crushing members, so that more uncrushed material can be loaded into the crusher, and it allows partially crushed materials to drop down in the crusher to the narrower regions of the throat. As indicated in EP-A-0 106 642, the size of the throat establishes the largest size of fragment that can be passed through the apparatus. I have found that it has up to now been necessary so to shape the pivoted first member, and so to locate its pivot axis, that the throat remains sufficiently constricted, even when fully open, to prevent oversize materials falling through at that stage in the crushing cycle.

I now propose to increase the potential throughput of crushing apparatus of this general kind by permitting a wider throat opening, while still controlling the fragment size.

According to this invention, a transverse member is provided in the crushing apparatus downstream of the throat, forming an obstruction in the path of material exiting from the crusher. This transverse member may be a bar or the like, parallel to the pivot axis of the first member, which divides the outflow of fragmented product and holds up oversized material until it has been sufficiently fragmented by further cycles of the apparatus. During this process, the transverse member may act as a supplementary fixed member against which crushing may take place, and it is accordingly recommended that it be robust, especially fracture tough and impact and abrasion resistant.

The transverse member may be plain, but it may alternatively be finned, thereby dividing the exit from the throat, at least in part, into a plurality of cells, to control fragment size in two perpendicular directions. The cells may be substantially rectangular. Flat slabs of uncrushed material cannot pass through such cells, but long steel reinforcing bars from reinforced concrete can still exit the apparatus.

In further aspects of the invention, the transverse member may be removable and may be replaceable. A replaceable transverse member admits the possibility of replacement by different members, such as bars of different properties, or bars provided with different fins, or with different numbers of fins. Thus a plurality of bars carrying no fins or fins of a variety of shapes and spacings may be provided for use with different materials, or for achieving different output product sizes.

Although the transverse member is primarily required to divide the output flow of fragmented product, in order to reduce the size of the largest fragment that can pass through the open throat, while still allowing a large volume of smaller fragments to pass, a similar transverse member may also be located at one side of the throat, especially when provided with one or a plurality of fins, to control fragment size. More than one transverse member, in any combination of locations, may be used. When provided with fins, the fins on the respective members may be staggered, or may be interleaved, or may be co-planar, according to the desired sizing of the fragmented product.

A transverse member may also be provided with deflector means, such as a plate or the like, to guide reinforcing bar or other throughput material on exiting from the apparatus.

A plurality of upstanding fins may also be provided on the fixed second crushing member, especially at the narrower portion of the throat of the apparatus, projecting towards the transverse member and/or the pivoted crushing member.

Such fins are effective in providing a kind of filter to prevent concrete pieces that might be sufficiently thin, but not sufficiently narrow, from falling through the apparatus; and to provide further alternating support surfaces (on the fin edges) and spaces between them for concrete to be pressed into before being fragmented free of the body being crushed.

The fin sizes may be such that the edges facing the pivoted first crushing member are about 50mm away from the nearest crushing region of the first crushing member when the apparatus is fully closed.

A further advantage of such fins is that they can provide a support for large slabs of concrete in the region of the apparatus where the crushing pressures are highest. Seen from the point of view of the slab, these fins appear edge-on as a row of widely spaced fingers extending from the fixed crushing member in the throat of the apparatus, between which the concrete can pass when it is sufficiently fragmented.

Fins may be mounted on a lower section of the second crushing member which is removable and/or adjustable for angle with respect to the fixed upper part of the second crushing member. Such adjustment will also affect the spacing from the pivoted first crushing member. Accordingly, different sets of fins on the transverse member or on the second crushing member, in different positions, can be used according to the sizing and grading required of the crushed and fragmented material passing through the apparatus.

A second aspect of the invention addresses the problem of materials that agglomerate in the apparatus, especially on the fixed second crushing member. As described in EP- A-0 106 642, loose movable members such as slackly hung chains may be provided between the crushing members to help dislodge fragmented material. In accordance with this second aspect of the present invention, the fixed second crushing member comprises a face plate backed by rigid support means, wherein regions of the face plate are normally spaced from the backing support means, but are resiliently deformable, in use, against the rigid backing support means, by crushing forces exerted by the pivoted first crushing member.

By this means, the face plate can flex during each cycle of the apparatus, and resist the build up of soft concrete, chalk or the like. Additionally, when materials fragment and collapse under the crushing pressure, the face plate may spring forward and impact against the smaller fragments to further enhance the crushing performance of the apparatus.

The face plate may be mounted directly on the support means, at spaced apart points or lines, or it may be separately mounted over the support means. Tough, abrasion resistant steels are available, in plate form, that can be made both strong and flexible enough over a limited range of movement.

The pivoted first crushing member may be provided with a plurality of individual concrete engaging teeth. The original engine crusher design envisaged a plurality of parallel bars extending across the face of the pivoted crushing member, and these may still be used. However, augmenting them with individual teeth located between the bars provides means for applying extremely localised force, and correspondingly high pressure, against the concrete, and the teeth can be located so as to take advantage of the weak tensile properties of concrete. The horizontal bars on the pivoted member, which may be continuous or discontinuous, are particularly useful in scraping small residual concrete fragments from the underlying steel reinforcing mesh.

The preferred distribution of projecting teeth is one in which there are more teeth, but shorter teeth, within the narrowest part of the throat of the crusher where the pressures are highest, and fewer teeth, but longer teeth, towards the entrance to the throat where the pressures are lowest. Some teeth may be removable, not only to replace them when worn, but mechanism, so that they can be removed in certain applications. For example, if a particularly long concrete slab is being fed into the apparatus, particular pressure on the slab at the highest point in the crusher throat might have the unwanted effect of snapping the slab prematurely.

The teeth, as well as the bars, on the pivoted first crushing member may be effective in stripping concrete off the underlying reinforcement.

The invention is illustrated by way of example in the accompanying diagrammatic drawings, in which:

Figure 1 is a side view, in cross-section, of a first embodiment of apparatus for fragmenting concrete in accordance with the invention, showing the jaw mechanism open;

Figure 2 is a similar side view showing the jaw mechanism partly closed;

Figure 3 is a detail in side elevation, illustrating the mounting of the flexible face plate of the apparatus;

Figure 4 is a rear elevation of the face plate;

Figure 5 is an elevation of a removable and replaceable transverse member in the form of a bar carrying a plurality of fins;

Figure 6 illustrates the mounting of the transverse member removably and replaceably in the apparatus; and

Figure 7 is a side view, in cross-section, of a second embodiment of apparatus for fragmenting concrete in accordance with the invention, showing the jaw mechanism both open and closed, and a variety of fin and bar forms.

The apparatus as shown in Figures 1 and 2 comprises a welded steel box structure 11 having one end closed by a composite fixed end wall 14. A pair of vertical side walls 15 (the farthest only being shown) extend from either side of rigid end wall 14 back towards the remote end of the box 11 , which includes a rearward extension 16 housing a hydraulic ram comprising a cylinder 18 and piston rod 19, with a top plate 20 and bottom plate 21 respectively above and below the cylinder 18 of the ram. The first crushing member of the apparatus is constituted by the front of a welded steel box structure 24 which is pivotally mounted on pivot axis 25. The box structure comprises a plurality of parallel vertical plates 26 perpendicular to the pivot axis 25, spaced apart across the apparatus between, spanned by five contiguous flat rectangular plates 31 , 32, 33, 34 and 35 facing generally in the direction of the composite end wall 14, but each being angled differently thereto. Piston rod 19 of the hydraulic ram engages the box structure 24, so that the ram can be used to drive the first crushing member pivotally towards the end wall 14, which is part of the second crushing member.

The rectangular plates 31 and 32 correspond to plates 25 and 24 respectively of the apparatus shown in EP-A-0 106 642. Plates 33 and 34 replace the upper plate 23 described in EP-A-0 106 642. The fifth and uppermost plate 35 does not in practice act as a crushing region, but as a shield for the piston rod 19 and as a flat funnel wall to assist in loading the fragmenting apparatus. The plates 31-34 are provided with either horizontally extending bars or rows of individual teeth 38 to localise the crushing forces against pieces of concrete 37 or rock or other material to be crushed, and to grip and shear this material as it passes downwardly through the apparatus.

The rigid composite end wall 14 comprises a plurality of narrow, interlocked and welded flat plates 22 extending vertically and horizontally across the apparatus. Edges 17 of the vertically extending plates 22 are curved, presenting a concave shape towards the first crushing member 24. The edges of some of the horizontally extending plates 22 are straight, and carry hardened steel horizontal cross bars 23. The combined conformation of edges 17 and bars 23 coincides with a notional curved surface that approximates to part of a cylinder having an axis lying above and parallel to the pivot axis 25. At the lower end of end wall 14, spaced apart vertical plates 39 project into the box 11. They extend generally towards, but at a lower level than, the first crushing member 24, and form a set of fins in the lowest portion of the throat 50 defined between the first and second crushing members.

The end wall 14 carries a steel plate 40 loosely over the inward facing edges 17 of interlocked plates 22 and the horizontal bars 23 of solid end wall 14, to complete the fixed second crushing member. Figs 3 and 4 illustrate the plate 40 and its means of attachment. The plate has a plurality of slots 42 cut into its lower edge. These slots accommodate the fin plates 39 in the crusher. The plate also has a plurality of slots 44 cut into its upper edge, and a bar 48 welded across the rear of the upper edge. The slots accept hooks 46 on the end wall 14 of the crusher. Hooks 46 support the bar 48.

In this way the plate 40 is hung in position, slightly inclined, carried by bar 48 on hooks 46 at its upper end, and resting at its lower end against the lowermost of the horizontal bars 23 of the end wall 14.

With the profiled horizontal bars or teeth 38 welded across the working face of the pivoted first crushing member, the apparatus as thus far described functions in essentially an identical manner to the engine crushing apparatus described in EP-A-0 106 642. However, the hanging plate 40 is sufficiently flexible and resilient that, under pressure from concrete lumps 37 driven by the pivoted first cushing member 24, it can bow backwards towards the notional curved surface of end wall 14, and return to its flat shape when the pressure is relieved. This can happen either when the first crushing member is withdrawn, or when a lump of concrete breaks under the pressure. In this second case, the plate 40 can spring back on to the resulting smaller fragments with such force that they in turn are fractured or weakened by the impact. The plate acts as a spring which converts potential energy into kinetic energy, to improve the efficacy of the crusher by mixing impact forces with pressure forces.

In an example, the plate 40 is made form Hardox (tm) 400 abrasion resistant high tensile steel plate 8mm thick, about 600mm wide, and about 380mm between the hanger bar 48 and the lower supporting bar 23 on end wall 14. The centre of plate 40 can be pushed back about 40 to 50mm before it is stopped from further movement by the notional curved surface of the rear wall. Other materials and dimensions can be used, provided that the plate recovers from flexing without significant fatigue.

The lowermost part of throat 50 , even when the pivoted first crushing member 24 is fully advanced towards end wall 14 and the fins 39 are taken into account, is sufficiently open to allow fragmented product to be discharged at a satisfactory rate. However, this would also allow a great range of sizes of product to pass out of the apparatus at the same time. In order to prevent larger fragments from being discharged and to provide a better graded product, a transverse member 52 is provided at the exit from the throat, and consists of a strong rigid bar 54 carrying a plurality of fins 56 made of steel plates spaced along the bar and perpendicular to it.

Figures 5 and 6 also show how the transverse member 52 is removably mounted on the crusher. One side wall 15 has an aperture large enough to allow the fins 56 to pass through, and a corresponding end of bar 54 carries a plate 60 that exactly fits the aperture, and a larger cap 62 that cannot enter the aperture. The opposite end of bar 54 passes through a corresponding aperture in the other side wall 15, where it is held by pin 64 passing through the bar and a boss 66 on the outside of this wall 15.

Figure 7 shows variations of the apparatus illustrated in Figures 1 to 6, with removable transverse members of different shapes, locations and functions, obstructing the crusher exit to varying degrees. All can be installed or removed in ways corresponding to that shown in Figure 6, or in any other convenient way.

The crusher shown in Figure 7 comprises a welded steel box structure 80 having one end closed by the second crushing member, a composite fixed end wall 82 made up of a slightly inclined but substantially vertical crushing plate 84 with a lower edge extended by supplementary plate 94, backed by transverse steel plates 83. Plates 83, 84 and 94 all extend fully across the box structure 80 from the near side wall to the far side wail 87, and are welded together and to the two side walls for maximum strength and rigidity. Crushing plate 84 and, to a lesser extent, extension 94, correspond to flexible plate 40 in Figures 1 to 6. However, in this embodiment, plates 84 and 94 are absolutely rigid. The steel can be the same as for plate 40, but since it does not have to flex, the plates can be made thicker.

Hydraulic ram 88 powers a box section first crushing member cyclically from its retracted position 86 to its advanced position 86' on its pivot axis 85. The member corresponds in all essentials of its structure with box section 24 (Figures 1 and 2), albeit with slightly different proportions. A throat 96 is defined between the pivoted first crushing member 24 and the second crushing member 84,94.

The two sides 87 of the apparatus are each provided with three similar openings 90, 92 and 98. The respective openings 90, 92 and 98 lie opposite the corresponding openings on the opposite side, and each has a similar profile to the opposite opening. Accordingly, each pair of openings can be used to mount a transverse member of any size that can be accommodated by the profile or outline of those openings.

The profiles shown in the drawing correspond to the largest shapes that can be inserted into the crusher in each case. Any smaller shape can be used that will pass through the same side wall aperture, such as a smaller bar with or without fins up to the size shown, provided that there is an end plate (corresponding to the plate 60 of Figure 6) of the size shown to fix the position of the transverse member in one wall 15.

Transverse member 70 consists of a plain, strong, rigid bar of the trapezoidal cross section illustrated, and carries no fins. It can be mounted in the openings 90, and divides the exit from the crusher into two channels at the exit from the throat 96.

Transverse member 72 consists of an inclined plate 74 braced by strengthening members 76 on its lower face. It can be mounted in the openings 92, where the inclined plate narrows the exit from the crusher throat and guides the discharge of crushed product.

Transverse member 78 consists of a plurality of spaced fins on a backing plate, and when mounted in openings 98 it gives means to provide the functionality of fins 39 (Figures 1 and 2) with means for changing their shapes, sizes and numbers, or for temporarily dispensing with them altogether.

Transverse members 70, 72 and 78 can be selectively removed or replaced by others of the same or smaller overall profiles. The discharge outlet can accordingly be varied in shape and size to control the outflow of crushed product and to provide additional crushing surfaces for the pivoted member to work material against. When fins are used, the cells formed between fins can be used to grade the product particularly finely.

Claims

CLAI S

1 Crushing apparatus comprising first and second crushing members, the first crushing member being pivotally mounted with respect to the second crushing member for co-operating with the second crushing member to crush materials therebetween, and the said crushing members defining between them a throat through which fragments of the materials can be discharged; characterised in that a transverse member is provided in the crushing apparatus downstream of the throat, adapted to divide the outflow of crushed fragments and hold up oversized material.

2 Crushing apparatus according to claim 1 , wherein the pivotally mounted first crushing member is provided with a plurality of crushing regions located at various distances from the pivot axis, which is offset, so that as the first crushing member is cyclically advanced towards and retracted from the second crushing member, successive crushing regions approach the second member closer than the preceding crushing region, whereby to crush the material by a combination of compression and shear forces.

3 Crushing apparatus according to claim 1 or claim 2, wherein the throat can be opened by retraction of the first crushing member from the second crushing member, and reduced in size by advance of the first crushing member towards the second crushing member.

4 Crushing apparatus according to any one of the preceding claims wherein the transverse member lies parallel to the pivot axis of the first member.

5 Crushing apparatus according to any one of the preceding claims wherein the transverse member is capable of holding up material in the throat of the apparatus to be crushed by advance of the first crushing member towards the second crushing member.

6 Crushing apparatus according to any one of the preceding claims wherein the transverse member comprises a robust bar. 7 Crushing apparatus according to any one of the preceding claims wherein the transverse member is finned, thereby dividing the exit from the throat, at least in part, into a plurality of cells, whereby to control fragment size.

8 Crushing apparatus according to any one of the preceding claims wherein the transverse member is removable and replaceable.

9 Crushing apparatus according to any one of the preceding claims comprising at least one additional transverse member in the outflow path of crushed fragments to further reduce the size of the largest fragments that can leave the throat.

10 Crushing apparatus according to any one of the preceding claims wherein a transverse member is provided with deflector means to guide throughput material exiting from the apparatus.

11 Crushing apparatus according to any one of the preceding claims wherein a plurality of upstanding fins are provided on the fixed second crushing member, projecting towards the transverse member and/or the pivoted crushing member.

12 Crushing apparatus according to any one of the preceding claims wherein the pivoted first crushing member is provided with a plurality of individual teeth for engaging material to be crushed.

13 Crushing apparatus according to claim 12 wherein there are provided more but shorter teeth within the narrowest part of the throat and fewer but longer teeth towards the entrance to the throat.

14 A method of crushing material between first and second crushing members, in which the first crushing member is pivotally mounted with respect to the second crushing member and with the second crushing member defines a throat through which fragments of materials are discharged after being crushed by advance of the first crushing member towards the second crushing member; characterised in that the outflow of crushed fragments from the throat is divided by a transverse member which holds up oversized material. 15 A method according to claim 14 wherein the pivotally mounted first crushing member is provided with a plurality of crushing regions located at various distances from the pivot axis, which is offset, so that as the first crushing member is cyclically advanced towards and retracted from the second crushing member, successive crushing regions approach the second member closer than the preceding crushing region, whereby to crush the material by a combination of compression and shear forces.

16 A method according to claim 14 or claim 15 wherein advance of the first crushing member towards the second crushing member crushes material against the transverse member.

17 A method according to any one of claims 14 to 16 wherein the size of the largest fragments that can leave the throat is further controlled by at least one of an additional transverse member in the outflow path of crushed fragments and a plurality of fins on a transverse member or on the second crushing member.