WO1992005094A1

WO1992005094A1 - Conveyor belt system

Info

Publication number: WO1992005094A1
Application number: PCT/AU1991/000348
Authority: WO
Inventors: Barry Barnett
Original assignee: Barnett Investments Pty Ltd
Current assignee: Barnett Investments Pty Ltd
Priority date: 1990-09-13
Filing date: 1991-08-08
Publication date: 1992-04-02
Anticipated expiration: 1993-03-13

Abstract

A conveyor belt system has an endless belt (25) mounted and driven on pulleys (27, 29 and 30). The belt (25) is adapted to receive sticky particulate load (11) at a first location on the upper surface of the underbelt run and can remove a substantial portion of the sticky load at a second location (27) on the underbelt run, to leave only a small remnant portion (32) of the sticky load on the belt (25). The configuration of the belt (25) is such that the surface of the belt upon which the remnant sticky load (32) is conveyed is either facing upwardly or, when facing downwardly, has an underlying portion of the belt (25) to capture any of the remnant sticky load (32) that detaches from the downwardly facing belt (25).

Description

CONVEYOR BELT SYSTEM FIELD OF INVENTION

The present invention relates to conveyor belts and particularly to conveyor belts used in the mining industry and other areas for conveying sticky particulate matter. BACKGROUND ART

Conventional conveyor belt systems, when used for conveying sticky material such as coal dug from a coal face of a mine, have a tail pulley at the end adjacent the site on the upperbelt run where material is loaded, a discharge pulley at the other end, and a drive pulley arrangement downstream thereof on the underbelt run.

Most of the coal falls off the end of the belt when the upperbelt run turns about the discharge pulley and this coal falls onto an underlying second conveyor belt that transports it along a second gallery in the mine.

A scraper abuts against the downward side of the belt that turns about the discharge pulley so as to remove onto the second belt any sticky material that has not fallen under gravity. However, the scraper may not remove all the sticky material due to damage of the scraper or belt or some sticky material being resistant to the action of the scraper. This remnant sticky material may, when it dries or is shaken, subsequently fall from the downwardly facing dirty surface cf the return underbelt run on its way to the tail pulley. This leads to dangerous accumulation of coal and other debris on the floor of the mine as well as wastage of product. One approach to overcoming this problem has been to have a first belt turnover mechanism axially twisting a portion of the underbelt run about 180° at or near one end of the underbelt run, and a second belt turnover mechanism twisting the underbelt run back to its original disposition at or near the opposite end of the underbelt run. However, this system is costly, and mechanically complex thereby making it vulnerable to frequent breakdown and adding to its cost in required maintainance. The present invention seeks to overcome the same problem by loading the material to be conveyed onto the underbelt run rather than the upperbelt run and configuring the conveyor belt in such a way that the dirty surface of the belt, when facing downwardly, always has a belt of the same system underneath it, so that falling debris will land onto the underbelt run, rather than the floor. By landing onto the underbelt run, the debris may then proceed to the unloading site where the debris may fall under gravity onto the second conveyor belt or, if required, may be subjected to the scraper a second time.

DISCLOSURE OF THE INVENTION

According to the invention, there is provided a conveyor belt system comprising endless belt means mounted and driven on a plurality of pulley means, the belt means having an upperbelt run and an underbelt run, the underbelt run being at all times beneath the upperbelt run, said belt means being adapted to receive sticky particulate load at a first location on the upper surface of the underbelt run, means for removing a substantial portion of the sticky load at a second location on the underbelt run but which may leave a small remnant portion of the sticky load thereon, wherein the configuration of the belt means is such that the surface of the belt upon which remnant sticky load is conveyed is either facing upwardly or when facing downwardly has an underlying portion of the belt means to capture any of the remnant sticky load that detaches from the downwardly facing belt means. In this specification and claims, the term "sticky particulate load" is defined as any load that has a quality whereby it may stick or adhere to the surface of the belt upon which it is conveyed and "remnant portion of the sticky load" is defined as the carry-back material of the load. Preferably, the above conveyor belt system is adapted for use in an underground mine to convey coal from the coal face at the end of a first gallery to a second conveyor belt system that is disposed along a second gallery of the mine. However, the conveyor belt system of the invention may also be adapted for use in other mining operations such as open cut or surface mining of coal, mineral ores and like materials, which are prone to sticking to the belts normally used to coney them. For instance, the invention may be applied in the mining of iron ore, bauxite and diamond bearing materials. Similarly, the conveyor belt system of the invention may be used in washeries, such as in uranium enrichment plants, or in any material handling environment that requires the bulk conveying of sticky material . Preferably, the means for removing a substantial portion of the sticky load is a 180° downward turn of the underbelt run around a first turn or discharge drive pulley, whereby a substantial portion of the sticky load falls from the belt under gravity.

It is preferred that the means for removing a substantial portion of the sticky load includes at least one belt scraper adapted to scrape off sticky load that has not fallen under gravity, the said scraper acting against the underbelt run as it rounds the first turn or discharge drive pulley.

Preferably, the scraper is any form of "soft" acting scraper which is known in the art. In this specification and claims, a "soft" acting scraper is defined as any scraper that has a scraper tip made of "soft" or flexible material such as rubber or wire, which material can readily flex or be urged away from a heavy or otherwise immoveable or sticky load, rather than urge against such a load and risk damage to the belt or scraper. The "soft" acting scraper should, however, be able to remove lightly adherent load. The "soft" acting scraper is distinct from conventional "hard" acting scrapers, such as those having tungsten carbide or high abrasian resistant ceramic tips, which may be damaged or cause damage to the belt when they urge against heavy or otherwise immoveable or sticky load.

The load that is removed from the underbelt run is preferably captured by a chute that feeds the load onto the belt of a second conveyor belt system that transfers it elsewhere along the mine.

It is further preferred that there is a second turn pulley downstream of the first turn pulley and the underbelt run negotiates a 180° downward turn, around the second turn pulley whereafter the load carrying belt surface is again facing upwardly. In this way, the load carrying or dirty belt surface, after having rounded the first turn pulley against which the scraper may act, rounds a second turn pulley shortly downstream thereof so as to complete an S-like turn and to allow the load carrying belt surface to once again face upwardly. This arrangement allows any load that is not caught by the chute or remnant load that falls off whilst the load carrying belt surface is facing downwardly to be captured by the load carrying surface of the lower positioned belt means. BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood and put into practical effect, reference will be made to the accompanying drawings in which:-

Fig. 1 is a schematic representation of a conventional underground trunk conveyor belt system, and Fig. 2 is a schematic representation of a conveyor belt system according to a preferred embodiment of the present invention applied to an underground trunk conveyor belt system. Fig. 3 is a schematic side view of a "soft" acting scraper acting against the first turn or discharge drive pulley of the conveyor belt system of Fig. 2. DESCRIPTION OF PREFERRED EMBODIMENT

The conventional underground trunk conveyor belt system shown in Fig. 1 may be used to convey coal 11 from the coal face 12 at the end of a first gallery 13 along a portion of an upperbelt run 13a to a second conveyor 14 (shown in cross- section) that conveys the coal 11 along a second gallery (not shown) of a mine. Most of the coal that reaches the end of the upperbelt run 13a falls therefrom under gravity as the belt rounds the discharge pulley 16. Although not shown, there is an impact plate and or a rock box located so as to deflect a substantial amount of the load downwardly onto a chute 22 feeding onto the belt 14 of a second conveyor system.

A scraper 15 abuts against the belt surface as it rounds the discharge pulley 16 and scrapes off onto the belt of the second conveyor 14 a substantial amount of the coal 11 that has not fallen under gravity. Two drive pulleys 17 and 18 support a portion of the underbelt run 19 in an S-like turn configuration.

A tensioning device 20 acting on a portion of the underbelt run 19 turning about a freely rotating idler pulley 21 serves to ensure that the belt is maintained at a predetermined tension. The tensioning device 20 may be in the form of an electrohydraulic winch or a gravity weight. After a substantial amount of the coal 11 has been removed from the upperbelt run 13a as described above a remnant portion of sticky or otherwise scraper resistant coal 23 is carried by the belt around the discharge pulley 16 so that it faces downwardly, whereupon some of the remnant coal may fall to the floor of the gallery or remain stuck on the belt. This stuck coal may, in time, dry and, if the belt is facing downwardly in its passage about the pulleys, fall to the fall of the gallery. The accumulation of fallen coal and other debris on the floor 24 of the mine gallery may pose a danger to the safety of the mine, lead to deterioration of the quality of the mine equipment and be wasteful of product. For instance, accumulation of coal on the floor of the mine gallery serves as a potential fire source as any hot componentry of mine equipment, such as the highly frictioned roller bearings supporting the underbelt run of the conveyor, may fall from the equipment due to fatigue of parts and cause the accumulated coal to ignite. The underground trunk conveyor belt system shown in

Fig. 2 overcomes this problem by being adapted to load coal 11 at a site on the underbelt run 25 and to convey the load along the underbelt run 25 toward a discharge drive pulley 27. A "soft" acting scraper 26 acts on the discharge drive pulley 27. The scraper 26 is described later with reference to Fig. 3. The conveyor belt system of Fig. 2 also has a tensioning device 33, a second drive pulley 29 and a series of freely turning idler pulleys 30 to complete an endless- track.

Load that falls from the belt 25 as it rounds pulley 27 or is subsequently scraped off falls into chute 28 that feeds onto a second conveyor belt 31 (shown in cross-section) .

Remnant sticky coal 32 is conveyed by the underbelt run about the second drive pulley 29 so as to complete an S-like turn configuration and to orientate the load carrying surface of the underbelt run back in an upwardly facing direction. The belt then turns about the series of freely turning idler pulleys 30, until the belt returns to the load site, and during this time the sticky remnant coal faces downwardly.

With this arrangement, it is apparent that the load carrying surface of the belt is only either facing upwardly or, when facing downwardly, has an underlying portion of the belt to capture any remnant load that detaches from the downwardly facing belt.

It is one advantage of the present invention that the scraper arm need not be made of heavy duty material or have a tungsten carbide tip as is conventionally used to withstand large load obstructions, but may be any "soft" acting scraper. The reason for this is that it is not as important in the present invention to remove sticky load out of concern that this will fall to the floor of the mine. A larger than normal amount of sticky load can be allowed to pass around the discharge pulley and so face downwardly, because of the presence of an underlying portion of the belt of the same system that can capture any falling load. Furthermore, only one "soft" acting scraper may be sufficient for use in certain circumstances rather than the several "hard" acting scrapers that are conventionally used. This will reduce belt wear and so lead to longer belt life.

The "soft" acting scraper 26 of Fig. 3 has an arm 35 pivotable about axis 36. As shown, the lower end of arm 35 has a weight 37 attached thereto and the higher end of arm 35 has a U-shaped member 38 attached thereto. The U-shaped member 38 has a rubber strip 39 bolted therewithin. The scraper 26 extends across the width of the belt 25.

In operation, the rubber strip 39 of the scraper 26 abuts as shown against the belt 25 as it turns around the pulley 27 by the presence of the weight 37 acting at the lower end of the pivotal arm 35. When the rubber strip 39 collides with load travelling on the belt 25, it will remove only that portion of the load equivalent to the removal capacity of the scraper 26, but will allow more sticky load to remain on the belt 25 by being deflected about pivot axis 36 away from the belt 25. After the sticky load has passed, the weight 37 will cause the rubber strip 39 to return and again abut against the belt 25 as shown.

It is another advantage of the present invention that it removes all possibility that the load carry-back will cause the gradual burying of and interference with the conveyor equipment, such as the drive pulleys and the roller bearings that support the underbelt run. It is a further advantage of the present invention that any load carry-back falls back onto the product stream, thereby reducing product wastage and the risk of fire.

The present invention also overcomes a problem in the prior art commonly referred to as "the tail pulley problem", where load spilt from the upperbelt run near the load site lands on the underbelt run adjacent to the tail pulley, thereby accumulating at the tail pulley and causing damage to the belt as it turns about the tail pulley. There is also the added risk of the belt tracking off the side of the tail pulley. The present invention can be seen as a "self cleaning" system whereby any remnant material falling from the underside of the upperbelt run will fall on the underbelt run that moves away from the tail pulley. Various other modifications apparent to those skilled in the art may be made in details of design and construction without departing from the scope or ambit of the invention.

For instance, in the coal mining industry, the present invention may be adapted for use as an underground longwall conveyor, an open cut surface main conveyor, a stockpile conveyor or any other form of both stationary or moveable coal handling conveyor assembly. It is further apparent that the present invention has broad application wherever sticky particulate material is sought to be conveyed, such as may be required in grain or sugar processing plants.

Claims

1. A conveyor belt system comprising endless belt means mounted and driven on a plurality of pulley means, the belt means having an upperbelt run and an underbelt run, the underbelt run being at all times beneath the upperbelt run, said belt means being adapted to receive sticky particulate load, as hereinbefore defined, at a first location on the upper surface of the underbelt run, means for removing a substantial portion of the sticky load at a second location on the underbelt run but which may leave a small remnant portion of the sticky load thereon, wherein the configuration of the belt means is such that the surface of the belt upon which remnant sticky load is conveyed is either facing upwardly or when facing downwardly has an underlying portion of the belt means to capture any of the remnant sticky load that detaches from the downwardly facing belt means.

2. The conveyor belt system of claim 1 wherein the means for removing a substantial portion of the sticky load is a 180° downward turn of the underbelt run around a first turn pulley, whereby a substantial portion of the sticky load falls from the belt under gravity.

3. The conveyor belt system of claim 2 wherein the means for removing a substantial portion of the sticky load includes at least one belt scraper adapted to scrape off sticky load that has not fallen under gravity, the said scraper acting against the underbelt run as it rounds the first turn pulley.

4. The conveyor belt system of claim 3 wherein the belt scraper is a soft acting scraper as hereinbefore defined.

5. The conveyor belt system of claim 4 wherein there is a second turn pulley downstream of the first turn pulley and the underbelt run negotiates a 180° downward turn around the second turn pulley whereafter the load carrying belt surface is again facing upwardly.

6. The conveyor belt system of claim 5 including a tensioning device to maintain operational tension on the belt.

7. The conveyor belt system of claim 6 including a chute adapted to capture load removed from the second location of the underbelt run.