GB2121378A

GB2121378A - Bridge apparatus for retrieval of material from bulk material stockpiles

Info

Publication number: GB2121378A
Application number: GB08312534A
Authority: GB
Inventors: Gunter Strocker
Original assignee: Gustav Schade Maschinenfabrik GmbH and Co
Current assignee: Gustav Schade Maschinenfabrik GmbH and Co
Priority date: 1982-05-21
Filing date: 1983-05-06
Publication date: 1983-12-21
Also published as: AU558291B2; GB8312534D0; FR2530594A1; ZA833644B; DE3219185A1; AU1481883A; DE3219185C2; GB2121378B

Abstract

Bridge apparatus for removing material from the face 2 of bulk material stockpiles 1 comprises a travelling bridge 4 carrying a plurality of retrieval carriages 10 spaced along it. Each carriage 10 has a retrieval chain 20 which circulates around the bridge. The retrieval chains 20 carry retrieval elements 22 which pick up the material and carry it up above the bridge 4 to discharge it to a conveyor 8. In operation the carriages 10 move to and fro along the bridge so that their working zones overlap. Preferably the carriages are connected together in a chain. Preferably the elements 22 are symmetrical so that the chains 20 are reversible and the apparatus can work with a stockpile on either side of the bridge 4. <IMAGE>

Description

SPECIFICATION Bridge apparatus for retrieval of material from bulk material stockpiles The invention relates to a bridge apparatus for the removal or retrieval of material from bulk material stockpiles, having a travelling bridge and a retrieval carriage which can move to and fro thereon in the longitudinal direction of the bridge and which is provided with an endless retrieval chain circulating about guide wheels, the retrieval elements of the said chain taking up the bulk material at the face slope of the stockpile in the region on the base of the pile and feeding it to a bridge conveyor, more particularly a belt conveyor.

For retrieving bulk material from storage and mixing stockpiles, these are the well-tried bridge scrapers. Besides these, it is also known to use bridge apparatus with a bridge which is capable of travelling in the direction of the pile axis, and a retrieval carriage mounted on the bridge which, when in operation, moves continuously to and fro longitudinally of the bridge and in so doing takes up the bulk material at or in front of the face slope of the pile with a retrieval chain circulating about the bridge and conveys the material upwards to a discharge point above the bridge, where the bulk material is transferred to a conveyor on the bridge (German OS 28 07 355).

Bridge apparatus of this or similar kind are not without their disadvantages. In the known bridge apparatus a bucket chain circulating about the bridge is used for the retrieval chain, and its buckets discharge the bulk material at the top onto the bridge conveyor as they circulate over on upper guide wheel which, because of the relatively large height of fall, may lead to undesirable comminuting effects on particle size. It is also disadvantageous that if material escapes from the face slope of the pile by trickling out, it is not possible to load all the bulk material; a more or less appreciable quantity of bulk material remains unloaded behind the bridge apparatus on the floor of the pile which the bucket chain cannot reach.

Known bridge apparatus can be used in both working directions of the bridge (i.e. the stockpile may be on either side of the bridge), but this requires more or less intricate re-arrangements.

The invention seeks to provide a bridge apparatus in which a more uniform and possibly also an increased delivery capacity is attainable, whilst achieving an improved homogenising effect. Preferred forms of the invention also enable the bulk material to be conveyed carefully without unnecessary particle damage, are capable of removing the material in its entirety, and have the bridge apparatus so constructed that it can operate in either working direction of the bridge without having to carry out complicated conversion work when changing the direction of working.

Broadly, the present invention provides a plurality of retrieval carriages on the bridge which may be arranged spaced sideways from one another. They are capable of moving to and fro in the longitudinal direction of the bridge with their working zones overlapping.

According to this invention there is provided apparatus for retrieving bulk material from a stockpile the apparatus having a travelling bridge to extend past and be movable towards a part of the surface of the stockpile, a bridge conveyor and a plurality of retrieval carriages on the bridge, movable to and fro along it so that their working regions overlap, each retrieval carriage having an endless retrieval conveyor bearing a plurality of retrieval elements, the conveyor and elements being arranged so that the elements pick up bulk material, lift it and feed it onto the bridge conveyor.

Preferably the reclaiming carriages are spaced apart from one another, wherein each retrieval conveyor is an endless scraper chain running over guide wheels on the carriage, and wherein the retrieval elements are troughs secured to the chains, each having an inclined edge portion remote from the chains to scrape up material, and an inclined edge portion nearer the chain, over which in use the material is discarded freely as the trought passes over an upper guide wheel.

With a bridge apparatus constructed in accordance with the invention, the bulk material is taken up simultaneously by a plurality of retrieval carriages distributed over the width of the stockpile. Consequently the individual elements may have a relatively small conveying volume and the total output of the apparatus can be more uniform. If required an increased delivery output can be achieved together with considerably improved homogenisation. It is possible for the number of retrieval elements arranged on the individual retrieval chains and/or the conveying speed of the individual retrieval chains, to be adapted to the varying cross-sectional size of the stockpile in the various working zones of the reclaiming chains. A plurality of individual drives of relatively low power can be provided for the retrieval chains.As already mentioned, the use of a plurality of retrieval carriages each of which is provided with a circulating retrieval chain offers the possibility of using retrieval elements which have a relatively small conveying volume. Instead of the conventional bucket chains, scraper chains are used which comprise scraper type supporting troughs as retrieval elements. The bulk material can be discharged from such shallow supporting troughs by no more than a moderate amount of inclination, so that it is not necessary to dump by tipping the retrieval elements upside down.

The apparatus can be so constructed that the retrieval chains circulate in a known manner about the bridge, and the retrieval carriages are each provided with guide wheels, arranged above and below the bridge, for the endless retrieval chains.

Advantageously, the retrieval chains are guided below the bridge over at least two guide wheels situated with approximately the same vertical spacing from the stockpile floor, so that the supporting troughs in front of the face slope of the stockpile travel over the stockpile floor with a scraping action between these guide wheels. This measure ensures that even when material has run down over the floor from the face slope the bulk material is substantially all taken up and loaded by the circulating retrieval chains.

To allow reverse operation (operation with the stockpile on the other side of the bridge) the supporting troughs can be constructed as double supporting troughs, with mirror-image symmetry about their plane extending at right angles to the direction of movement of the chain. In a preferred embodiment they are formed of supporting plates which at their free ends (i.e. those away from the chain) have mirror-image symmetrical double scraper flanges which are inclined relative to each other to form a V, these flanges forming supporting trough edges which project one above and one below the supporting plate surface. The supporting plates conveniently also have a symmetrical V-shaped arrangement of discharge plates at the side at which they are fastened to the chains, over which the bulk material will slide as it is discharged.These discharge plates serve both as boundaries for the shallow supporting troughs and as runoff surfaces when the bulk material is being discharged. The retrieval elements move in the manner of scrapers over the stockpile floor, and as they do so they carry along the bulk material when they reach the guide wheel situated near the face slope of the stockpile, they turn, pick the material up, lift it to the discharge station which is above the bridge conveyor. if the drive of the retrieval chains is reversible, then it is possible to work it in either direction of travel of the bridge without any conversion work being needed on the chains when using such retrieval elements.

According to a further preferred feature of the invention the retrieval carriages are coupled together to form a train of carriages. This makes it possible also to provide a joint feed drive for the retrieval carriages. The feed drive used may be e.g.

a cylinder drive or in a preferred form an endless drive element e.g. a chain system arranged at the bridge, and having at least one entrainment element which is guided advantageously in a vertical guide slot of the retrieval carriage train.

The reciprocating working movement of the train of retrieval carriages can, therefore, be achieved in this case with a continuously circulating driving band or the like.

In a further advantageous feature of the bridge apparatus according to the invention each retrieval carriages is associated with its own slope-loosening device, preferably in the form of a harrow or the like, the inclination of which is advantageously adjustable. The slope-loosening devices move over the face slope of the stockpile as the retrieval carriages move to and fro, and in the process loosen up the bulk material sufficiently to make it flow down the slope so that it can be taken up at the foot of the stockpile by the retrieval chains. A separate drive is not needed for the slope-loosening devices.

It is also recommended that there should be provided at the bridge above the bridge conveyor a loading trough which extends over the entire length of the bridge and into which the retrieval carriages deposit the bulk material. The loading trough also has the function of an intermediate bunker, facilitating the control of the entire installation when fluctuations occur in the bulk material quantities delivered by the retrieval elements.

An embodiment of the invention, given by way of example, will now be described with reference to the accompanying drawings, in which: Fig. 1 shows a bridge apparatus embodying the invention in a view in the direction towards the end slope of a bulk material stockpile from which material is being retrieved; Fig. 2 shows the bridge apparatus of Fig. 1 in a vertical section through its bridge; Fig. 3 shows on a large scale a vertical section through the bridge to illustrate an individual retrieval carriage; Fig. 4 shows a section taken on the line IV-IV of Fig. 3; Fig. 5 shows in section a retrieval element constructed as a supporting trough which is used in the bridge apparatus of Figs. 1 to 4.

The illustrated bridge apparatus operates on the face slope 2 of a bulk material stockpile 1 which has been dumped in a trough or channel 3.

The bridge apparatus comprises a bridge 4 which extends over the entire width of the stockpile base and which, as Figs. 2 and 3 show more particularly, comprises a stable box girder and is supported and guided at its two ends by means of driven running wheels 5 on rails 6. The rails 6 are laid at ground level on both sides of the stockpile 1 and extend parallel to the longitudinal axis of the stockpile 1, which in the embodiment illustrated is a longitudinal stockpile. In the case of a circular stockpile the bridge 4 would carry out a pivoting movement about the centre point of the stockpile, and the external rail 6 would be an annular rail.

At one side of the stockpile 1 there is a fixed storage area belt 7 next to the rail 6, on to which the belt 7 the bridge apparatus dumps the bulk material retrieved from the pile 1. The bridge apparatus 4 comprises a bridge conveyor 8 in the form of a belt system which is situated at the upper side of the bridge 4 and which extends substantially over the entire length of the bridge.

The discharge end 9 of the bridge conveyor 8 is situated above the storage area belt 7.

A plurality of retrieval carriages 10 are arranged on the bridge 4, from one another. The retrieval carriages 10 are coupled together by means of connecting elements 11 to form a retrieval carriage train capable of being moved to and fro in the longitudinal direction of the bridge. The distance involved in this to and fro movement is somewhat greater than the greatest lateral spacing between the retrieval carriages 10, so that the working zones of the retrieval carriages overlap one another somewhat. The retrieval carriages 10 are substantially of identical construction. As more particularly Figs. 3 and 4 show, they comprise a frame 12 which surrounds the bridge 4 and which bears on and can roll on wear-resistant running rails 14 on the upper side of the bridge 4 by means of topside running wheels 13.At some distance below the running wheels 13 there are side wheels 1 5 which serve as side guides and which bear against and roll on wear-resistant running rails 1 6 in the lower region of the bridge 4. The travelling frame 12 also extends around the bridge conveyor 8 which is situated on the upper side of the bridge 4. Three guide wheels 1 7, 18 are mounted on the travelling frame 12, and consist in each case of a plurality of coaxial chain wheels or one chain wheel with a plurality of chain wheel rims.The two lower guide wheels 1 7 are arranged in a mirror-image symmetrical arrangement about the vertical central plane of the bridge 4 and of the travelling frame 12, and are situated at the same height as each other above the stockpile floor 1 9. The upper guide wheel 18 is situated laterally half-way between the two-lower guide wheels 1 7 and vertically above the bridge 4 and the bridge conveyor 8. An endless retrieval chain 20 constructed in the manner of a scraper chain is guided about the guide wheels 1 7 and 1 8. This retrieval chain comprises one or more endless flatlink chains 21 which are fitted with retrieval elements 22. The driving of the retrieval chain 20 is effected e.g. by means of the driven upper guide wheel 18.

As Figs. 3 and 5 show more particularly, the retrieval elements 22 comprise shallow scraperlike supporting troughs formed of supporting plates 23 which at their free ends remote from the chains 21 comprise scraper strips or flanges 24 which are inclined in a V relative to one another in mirror-image symmetrical manner, and which form inclined trough edges which project above and below the level of the supporting plates 23. At the ends fastened to the chain, the supporting plates 23 of the supporting troughs are connected to discharge plates 25 which are inclined in a Vshape relative to one another, which form the edges of the supporting troughs, and which at the same time serve for connecting the retrieval elements 22 to the chains 21.Projecting side edge flanges 26 may also be provided on the supporting troughs extending above and below the supporting plates 23 (to the front and rear considered in the direction of chain travel).

As the drawings show, the retrieval elements 22 are mirror-image symmetrical about the plane of the supporting plate 23, so that the retrieval elements can work in either direction of circulation of the retrieval chain system and thus in either direction of travel of the bridge 4. In Fig. 3 the direction of circulation of the retrieval chain 20 is indicated by the arrow F. The lower guide wheels 17 are situated at such a spacing from the stockpile floor 1 9 that the scraper flanges 24 move with a scraping action over the stockpile floor 1 9 in the region between these guide wheels 17, and in so doing carry along any bulk material which may be situated in that region.As the retrieval elements 22 turn about the lower guide wheels 1 7 situated towards the stockpile 1, they move through the bulk material at the base of the face slope 2, and as they do so they take up the bulk material and then lift it in the direction shown by the arrow F into the region of the upper guide wheel 18, where it is dumped on to the troughshaped upper run of the bridge conveyor 8. During the discharging action the inclined discharge plates 25 serve as sliding surfaces over which the bulk material slides from the supporting plates 23 towards the chain side, as indicated by the arrows F' in Fig. 3.

Since all the retrieval carriages 10 are coupled to form a train of retrieval carriages it suffices if only a single propulsion or feed drive is provided for them. In the illustrated preferred constructional example this feed drive comprises a continuous band drive 27 comprising two parallel endless chain bands 28 which are driven and guided about chain wheels 29 and 30 (Figs. 3 and 4). The two chain bands 28 are connected by means of an entrainment element 31 which consists of a cylindrical pin or the like. One of the retrieval carriages 10 in the train, preferably a carriage situated in the central region of the train, has a projecting bracket 32 on its travelling frame 12 in the lower region between the guide wheels 1 7.

The bracket extends between the two endless chain bands 28 and has a vertical guide slot 33 through which the entrainment element 31 passes. During the retrieval work the chain bands 28 move continuously in the direction of the arrow S (Fig. 4). By means of the entrainment element 31 the relevant retrieved carriage 10, and thus the entire train of retrieval carriages, is carried along.

When the entrainment element 31 reaches the chain wheels 29 and turns about these, it moves upwardly in the guide slot 33, while the train of retrieval carriages is not moved substantially along the bridge. Then the entrainment element 31 moves in the opposite direction towards the chain wheels 30 and so the train of retrieval carriages is driven in the opposite direction along the bridge.

Thus this feed drive allows the retrieval carriages 10 be driven to and fro along the bridge without the drive having to reverse.

A loading trough is arranged above the bridge conveyor 34 (see Fig. 3, this has been omitted from Fig. 1 for the sake of clarity). The loading trough 34 extends over substantially the entire length of the bridge 4 and forms an intermediate storage container into which the retrieval carriages 10 discharge the bulk material removed from the stockpile 1.

Associated with each retrieval carriage 10 is its own slope-loosening device 35, which preferably is constituted by a harrow or the like. The slopeloosening devices 35 are joined to the travelling frames 12 of the retrieval carriages 10 at pivotable base joints 36 so as to be pivotable in a vertical direction, so that they can be adjusted to different inclinations of the stockpile face slope 2. The angle of inclination is adjusted e.g. by means of winch ropes 37 or the like (Fig 2). As is known the harrows comprise teeth 38 or the like which loosen the bulk material at the face slope 2 of the stockpile 1, so that it flows down the face slope into the region of the retrieval chain 20, where it can be engaged and taken up by the circulating retrieval elements 22.

So that the illustrated bridge apparatus can also work in the opposite direction of travel of the bridge 4, each retrieval carriage 10 has a second slope-loosening device 35' on its other side, arranged symmetrically with the first (Fig. 2).

As Fig. 1 shows, the slope-loosening devices 35 of the individual retrieval carriages 10 have different heights in accordance with the varying heights of the pile in the respective working regions of the retrieval carriages. Since the pile regions engaged by the individual carriages 10 are of different heights it is recommended that the conveying capacity of the individual retrieval chain systems be adapted to the particular pile area from which material is being removed, thus the retrieval carriages situated in the central region of the bridge have a markedly greater conveying capacity than the carriages which are situated at the ends of the bridge.The speed of circulation of the retrieval chains and/or the number of retrieval elements on the retrieval chains in the carriages 10 situated at the ends of the bridge may be less than in the case of the carriages in the centre of the bridge. Fig. 1 shows that the spacing between the retrieval carriages 10 situtated in the central bridge region is smaller than between the retrieval carriages working in the end regions of the bridge.

As has been mentioned, the distance which the carriages 10 travel along the bridge is so adjusted that the working areas of the individual carriages 10 in their to and fro movement overlap somewhat, so that all the bulk material at the foot of the face slope 2 is loaded up.

During retrieval the bridge 4 moves at a continuous speed on the rails 6 towards the stockpile. The to and fro movement along the bridge is given to the carriages 10 on the bridge by the feed drive 27. In this shuttle movement, the slope-loosening devices 35 also move over the face slope 2, so that the bulk material flows down the slope and can be collected by the retrieval elements 22 of the circulating retrieval chains 20, as is shown in Fig. 3. Even when material runs down and away from the face slope 2 the bulk material is all loaded up, since the elements 22 move with the scraping action over the stockpile floor 1 9 in front of the base of the face slope 2 over a distance which corresponds approximately to the spacing apart of the lower guide wheels 17.

In this movement the elements 22 enter the bulk material at the foot of the face slope 2, and as they move around the guide wheel 17 near the slope may pick up the material. Since bulk material is collected simultaneously by a large number of retrieval elements 22 distributed over the stockpile width, and dumped via the loading trough 34 onto the bridge conveyor 8, good homogenisation is obtained. The bulk material can also be retrieved with little digging and therefore damage to the individual particles is reduced. The retrieval carriages can operate below ground level, which has the added advantage of increasing storage capacity. The relatively small conveying volume of the retrieval elements 22 constructed as supporting troughs results in a more uniform delivery capacity.

Claims

1. Apparatus for retrieving bulk material from a stockpile, the apparatus having a travelling bridge to extend past and be movable towards a part of the surface of the stockpile, a bridge conveyor and a plurality of retrieval carriages on the bridge, movable to and fro along it so that their working regions overlap, each retrieval carriage having an endless retrieval conveyor bearing a plurality of retrieval elements, the conveyor and elements being arranged so that the elements pick up bulk material, lift it and feed it onto the bridge conveyor.

2. Apparatus according to claim 1 wherein the reclaiming carriages are spaced apart from one another, wherein each retrieval conveyor is an endless scraper chain running over guide wheels on the carriage, and wherein the retrieval elements are troughs secured to the chains, each having an inclined edge portion remote from the chain to scrape up material, and an inclined edge portion nearer the chain, over which in use the material is discarded freely as the trough passes over an upper guide wheel.

3. Apparatus according to claim 2 wherein the bridge conveyor is a belt conveyors

4. Apparatus according to any one of the preceding claims wherein each retrieval carriage extends around the bridge and is provided with guide wheels for its retrieval conveyor, which wheels are situated above and below the bridge.

5. Apparatus according to any one of the preceding claims wherein each retrieval conveyor is guided by two guide wheels at the same height below the bridge.

6. Apparatus according to any one of the preceding claims wherein each retrieval conveyor is guided by two guide wheels spaced apart below the bridge, and a third guide wheel above the bridge and centrally between the first two.

7. Apparatus according to any one of the preceding claims in which each retrieval element is symmetrically about a plane at right angles to the direction of movement of its retrieval conveyor, so that each retrieval coneyor and its associated elements are operable in either direction of movement of the retrieval conveyor.

8. Apparatus according to claim 7 in which each element has two said inclined surfaces at its edge portion remote from the conveyor, disposed in a V shape symmetrically about a plane at right angles to the direction of movement of the conveyor.

9. Apparatus according to claim 7 or claim 8 in which each retrieval element has two inclined surfaces at its edge portion towards the conveyor, disposed in a V shape symmetrically about a plane at right angles to the direction of movement of the conveyor.

10. Apparatus according to any one of the preceding claims which each said retrieval carriage has means for loosening the part of the surface of the stockpile above its working zone.

11. Apparatus according to claim 10 in which the loosening means is arranged to extend up the surface of the stockpile and the angle of inclination of the loosening means is adjustable.

12. Apparatus according to claim 11 or claim 12 in which the said loosening means is in the form of a harrow.

13. Apparatus according to any one of the preceding claims in which the said retrieval carriages are driven to and fro along the bridge by a common drive.

14. Apparatus according to claim 1 3 in which the said carriages are coupled together in a train so that the carriages move to and fro together.

1 5. Appartus according to claim 14 in which the carriage drive includes an endless drive element on the travelling bridge bearing an engagement element which engages the train of carriages.

1 6. Apparatus according to claim 1 5 in which the engagement element engages a vertical slot in a retrieval carriage or in the train of carriages, so that the train is driven to and fro by continuous and unidirectional movement of the endless drive element.

17. Apparatus according to claim 16 with the endless drive element located beneath the travelling bridge.

1 8. Apparatus according to any one of the preceding claims in which the retrieval carriages disposed near the centre of the bridge have a greater material retrieval capacity than those near the ends of the bridge.

1 9. Apparatus according to claim 18 in which retrieval conveyors of the said central carriages are arranged to operate at a greater speed than those of the carriages near the ends of the bridge.

20. Apparatus according to claim 19 in which the retrieval conveyors of the said central carriages bear more retrieval elements than those of the carriages nearer the ends of the bridge.

21. Apparatus according to any one of the preceding claims in which the carriages are disposed spaced apart along the bridge with a spacing greater near the ends of the bridge than near the centre of the bridge.

22. Apparatus according to any one of the preceding claims in which the travelling bridge has a loading trough extending along it over the said bridge conveyor, the retrieval elements being arranged to discharge material into the trough and the trough to discharge the said material onto the bridge conveyor.

23. Apparatus for retrieving bulk material from a stock pile substantially as herein described with reference to the accompanying drawings.