AU729519B2

AU729519B2 - Control system for overburden discharge

Info

Publication number: AU729519B2
Application number: AU79903/98A
Authority: AU
Inventors: Marcel Andre Turner
Original assignee: BHP Coal Pty Ltd
Current assignee: BHP Coal Pty Ltd
Priority date: 1997-08-12
Filing date: 1998-08-12
Publication date: 2001-02-01
Anticipated expiration: 2018-08-12
Also published as: AU7990398A

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): BHP COAL PTY LTD A.C.N. 010 595 721 Invention Title: CONTROL SYSTEM FOR OVERBURDEN DISCHARGE The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 CONTROL SYSTEM FOR OVERBURDEN DISCHARGE The present invention relates to open cut mining.

The present invention relates particularly to a system for controlling the discharge of a mined material from a mining means onto a transfer conveyor belt.

The present invention relates more particularly, although by no means exclusively, to a system for controlling the discharge of overburden from a discharge boom of a bucketwheel mining means onto a transfer conveyor 15 belt via a hopper car.

In open cut mining it is known to use a bucketwheel or other large scale mining means located on a mine floor to remove overburden from the face of a wall of the mine.

The bucketwheel is mounted on tracks that enable it to move along the length of a mine wall and to cut into the wall. Typically, the length of the mine wall is 2.4 25 km, the wall height up to 25m, and the cut into the wall made by the bucketwheel is 40-45m.

When the bucketwheel reaches the end of the length of the wall, typically, the bucketwheel is returned to the other end and the process of cutting into and moving along the length of the wall is repeated.

The overburden removed by the bucketwheel is transferred via a discharge boom of the bucketwheel into a hopper car and via the hopper car onto a transfer conveyor belt that runs parallel to and spaced from the wall.

Typically, the conveyor belt is 70m from the cut wall. ,The \\melbOl\homeS\Juanita\Keep\Patents\BHP P08535 AU COMPLETE.doc 12/08/98 3 overburden is transported by the conveyor belt and by connecting belts to stockpiles.

The hopper car straddles the conveyor belt and travels on rails on each side of the belt. The hopper car includes a hopper defined by front, rear, and side walls, a base which includes a chute for transferring overburden onto the conveyor belt, and a mechanical roller assembly inside the chute which prevents direct impact on the conveyor belt of overburden falling down from the discharge boom and assists in breaking up larger rocks in the overburden.

The hopper car interrupts the flow of overburden 15 from the discharge boom onto the conveyor belt and thereby minimises the impact of the overburden falling onto the belt and the damage to the belt caused by the impact.

It is important to control the delivery of overburden onto the conveyor belt so that the conveyor belt tracks correctly and there is minimal loss of overburden from the belt.

One significant problem arising from the loss of 25 overburden, particularly rocks, from the conveyor belt is that the overburden can actuate safety pull ropes that run along full lengths of the conveyor belt on both sides of the conveyor belt for safety purposes.

The actuation of a safety pull rope causes a system trip which shuts down all conveyor belts, causes excessive wear on the conveyor brakes, and excessive motor stress and load when restarting conveyor belts which are loaded with overburden.

On average, lost time caused by overburdenactuated safety pull ropes amounts to approximately one \\melbOl\home$\Juanicta\Keep\Patents\BHP P08535 AU COMPLETE.doc 12/08/98 4 hour per shift. It can readily be appreciated that this is a significant amount of lost time.

Lateral drift of the conveyor belt relative to the hopper car is one factor that is relevant to the loss of overburden from the conveyor belt. Lateral drift can be as much as 600mm for a belt width of 1800mm. Lateral drift is caused by a series of factors including, by way of example: factors associated with delivery of overburden and more particularly distribution of overburden onto the conveyor belt; and (ii) factors associated with the conveyor belt modules and stringers.

With regard to item (ii) the conveyor belt is continuous and is supported over its length by a series of support modules arranged end to end. If the modules are out of alignment which can occur without difficulty in a practical mining operation this can cause lateral drift of the belt with respect to the hopper car.

An object of the present invention is to provide a system for controlling discharge of overburden from a discharge boom of a bucketwheel onto a conveyor belt via a hopper car which minimises the problem of overburdenactuated safety pull ropes described above.

According to the present invention there is provided a system for controlling discharge of a mined material from a mining means onto a transfer conveyor belt via a hopper car which straddles the conveyor belt and travels along the length of the conveyor belt-and has an outlet for discharging the mined material onto the conveyor \\me IbO 1\hoe$ \Juan i t\Keep\Patent\HP P08535 AU COI4PLETE.doc 12/08/98 5 belt, which system comprises: a sensor means for sensing the extent of lateral drift of the conveyor belt relative to the hopper car; and (ii) a control means responsive to the extent of lateral drift of the conveyor belt relative to the hopper car as determined by the sensor means for controlling the position of delivery into the hopper car of mined material from the mining means to produce .se. discharge of the mined material from the hopper car onto the conveyor belt with 15 minimal loss of the mined material from the conveyor belt and/or to reduce the lateral drift of the conveyor belt relative to the hopper car.

It is preferred that the mined material be overburden.

It is preferred that the mining means comprise a discharge boom having a discharge end for discharging the 25 mined material into the hopper car.

It is preferred particularly that the mining means be a bucketwheel.

It is preferred that the sensor means be adapted to detect metal in or associated with the conveyor belt.

It is preferred that the conveyor belt comprise metal.

It is preferred particularly that the conveyor belt be made from a wire-reinforced elastomeric material.

X\\mel bO I\home$S\Juanjito\ Keep\ Patent S\BHP P08535 AU COMPLE'TE.doc 12/08/98 6 Alternatively, it is preferred that the conveyor belt be made from a non-metallic material and comprise a metallic marker means on the belt.

It is preferred that the sensor means comprise an array of spaced-apart metal detectors which are positioned to extend laterally to the direction of movement of the conveyor belt above or below the conveyor belt so that, in use, the position of a side of the conveyor belt is determined to be between two adjacent metal detectors when one of the detectors detects metal and the other detector does not detect metal.

It is preferred particularly that the array of metal detectors be mounted on the hopper car.

It is preferred more particularly that the array of metal detectors be mounted on the hopper car at a forward end of the hopper car above or below the entry of 20 the conveyor belt beneath the hopper car.

It is preferred that the control means be adapted to adjust automatically any one or more of: a 25 the forward and backwards movement of the hopper car relative to the mining means; (ii) the height of the discharge outlets of the discharge boom above the hopper car; and (iii) the slew of the discharge boom relative to the hopper car; in response to the lateral drift of the conveyor belt relative to the hopper car as sensed by the sensor means.

S It is preferred that the control means be adapted \\me Ib...f iles\homeS\ .Co les\Keep\ Spec i\79903 -99. doc 26/07/00 7 to move the hopper car automatically with the mining means.

It is preferred that the system includes an assembly of a deflector shield mounted to the discharge boom and an ultrasonic pulse generator/sensor mounted to the hopper car for determining the relative position of the hopper car and the discharge boom and that the control means is responsive to the relative position to actuate drive of the hopper car as required to track the hopper car with the mining means.

The present invention is described further by way of example with reference to the accompanying drawings, of which: Figure 1 is a schematic top plan view of an overburden removal system; and Figure 2 is a detailed view of the hopper car shown in Figure 1.

Figure 1 illustrates schematically an overview of o *o* a typical overburden removal system in an open-cut mine.

0** The overburden removal system includes a 25 bucketwheel 3 which cuts overburden from a wall 5 of the mine and discharges the overburden via a discharge boom 7 of the bucketwheel 3 onto a hopper car 11 which travels on rails 9.

In turn, the hopper car 11 delivers the overburden via a chute (not shown) in the base of the hopper car 11 onto a transfer conveyor belt 13.

The transfer conveyor belt 13 forms part of a network of conveyor belts, which includes conveyor belt which transport the overburden to a stockpile (not shown).

\\melb-files\home\L.jColes\Keep\Speci\79903-98.doc 2 6/07/00 8 The basic construction of the bucketwheel 3 (including the discharge boom the hopper car 11, and the conveyor belt 13 are conventional.

In accordance with a preferred embodiment of the present invention, a sensor means 17 is mounted on the forward end of the hopper car 11 to detect the lateral position of the conveyor belt 13 relative to the hopper car 11.

The conveyor belt 13 is made from a wire reinforced elastomeric material. The sensor means 17 comprises two separate arrays of inductive tracking devices (not shown) for detecting metal in the conveyor belt 13.

Each array comprises a plurality of tracking devices which are spaced apart and extend laterally to the direction of movement of the conveyor belt 13. The arrays are positioned to detect the sides of the conveyor belt 13.

Specifically, the arrays are positioned above or below the *the conveyor belt 13 in the region of the sides of the conveyor belt 13. The tracking devices are appropriately shielded to minimise interference from metal other than metal in or on the conveyor belt 13.

It can readily be appreciated that in use of the sensor means 17 the position of the sides of the conveyor belt 13 relative to the hopper car 11 (and therefore the lateral drift of the conveyor belt 13 relative to the hopper car 11) is determined to be between adjacent tracking devices in each array when one of the tracking devices detects metal and the adjacent tracking device does not detect metal.

The above-described sensor means 17 forms part of a preferred embodiment of a system for controlling discharge of overburden onto the conveyor belt 13 in \\melb-files\home$\LJColes\Keep\Speci\79903-98.doc 26/07/00 9 accordance with the present invention.

The system further comprises a control means (not shown) which is responsive to the lateral drift of the conveyor belt 13 relative to the hopper car 11 as determined by the sensor means 17 to control the position of discharge of overburden from the discharge boom 7 into the hopper car 11. The control means is designed to take into account the lateral drift of the conveyor belt 13 (and other relevant factors) in determining the optimum distribution of overburden in the hopper car 11 to produce discharge of overburden from the hopper car 11 onto the conveyor belt 13: with minimal loss of overburden from the conveyor belt 13; and/or (ii) to move the belt 13 to reduce the lateral *drift.

The control means is adapted to adjust automatically any one or more of the following parameters to achieve the optimum distribution: the forward and backwards movement of the hopper car 11. relative to the bucketwheel 3; (ii) the height of the discharge boom 7 above the hopper car 11; and (iii) the slew of the discharge boom 7 relative to the hopper car 11.

The control means is also designed to move the hopper car 11 automatically with the bucketwheel 3. In Athis regard, the relative position of the bucketwheel 3 and \\melbi les\home$\ LJColes\Keep\Speci\79903-98 .doc 26/07/00 10 the hopper car 11 is determined by an assembly of a deflector shield (not shown) welded to the end of the discharge boom 7 and an ultrasonic pulse generator/sensor (not shown) mounted on the hopper car 11 which transmits ultrasonic pulses towards the deflector shield and detects ultrasonic pulses reflected from the shield. At any point in time, the radial distance of the contact location of an ultrasonic pulse with the shield from a centrepoint on the shield is an indication of the relative position of the bucketwheel 3 and the hopper car 11. The control means responds to the relative position to actuate drive of the hopper car 11 as required to track the hopper car 11 with the bucketwheel 3.

The above-described preferred embodiment of the discharge control system of the present invention is an effective and reliable means of controlling discharge of overburden onto the conveyor belt 11 to minimise overburden actuated safety pull rope tripping of the overburden removal system.

Many modifications may be made to the preferred embodiment of the present invention described above without departing from the spirit and scope of the present invention.

S: For example, whilst the sensor means of the preferred embodiment comprises inductive tracking devices, it can readily be appreciated that the present invention is not so limited and extends to any suitable sensor means.

Furthermore, whilst the preferred embodiment is described in the context of discharging overburden, it can readily be appreciated that the invention is not so limited and extends to discharging any mined material.

SIn this specification, except where the context \\melbfiles\ome$\LdJColes\Keep\Speci\79903-98 .doc 26/07/00 11 requires otherwise, the words "comprise" and "comprises" mean "include" and "includes" respectively, i.e. when the invention is described or defined as comprising specified features, various embodiments of the same invention may also include additional features.

\\melb-files\home$\.aColes\Keep\Speci\79903-9.doc 26/07/00

Claims

1. A system for controlling discharge of a mined material from a mining means onto a transfer conveyor belt via a hopper car which straddles the conveyor belt and travels along the length of the conveyor belt and has an outlet for discharging the mined material onto the conveyor belt, which system comprises: a sensor means for sensing the extent of lateral drift of the conveyor belt relative to the hopper car; and (ii) a control means responsive to the extent of lateral drift of the conveyor belt relative ;i to the hopper car as determined by the sensor means for controlling the position of delivery into the hopper car of mined material from the mining means to produce 20 discharge of the mined material from the hopper car onto the conveyor belt with minimal loss of the mined material from the conveyor belt and/or to reduce the lateral drift of the conveyor belt relative to the 25 hopper car.

2. The system defined in claim 1 wherein the mining means comprises a discharge boom having a discharge end for discharging the mined material into the hopper car.

3. The system defined in claim 1 or claim 2 wherein the mining means is a bucketwheel.

4. The system defined in any one of the preceding claims wherein the sensor means is adapted to detect metal in or associated with the conveyor belt. \.\nelb files\holne$\LJColes\Keep\speci\79903-99 .doc 26/07/00 13 The system defined in claim 4 wherein the conveyor belt comprises metal.

6. The system defined in claim 5 wherein the conveyor belt is made from a wire-reinforced elastomeric material.

7. The system defined in claim 5 wherein the conveyor belt is made from a non-metallic material and comprises a metallic marker means on the belt.

8. The system defined in any one of claims 4 to 7 wherein the sensor means comprise an array of spaced-apart metal detectors which are positioned to extend laterally to the direction of movement of the conveyor belt above or below the conveyor belt so that, in use, the position of a side of the conveyor belt is determined to be between two adjacent metal detectors when one of the detectors detects metal and the other detector does not detect metal.

9. The system defined in claim 8 wherein the array of metal detectors is mounted on the hopper car.

10. The system in claim 9 wherein the array of metal detectors is mounted on the hopper car at a forward end of *the hopper car above or below the entry of the conveyor S: belt beneath the hopper car.

11. The system defined in claim 2 or any one of claims 3 to 10 when these claims are dependent on claim 2 wherein the control means is adapted to adjust automatically any one or more of: \\melb-files\homeS\.JColes\Keep\Speci\79903-98.doc 26/07/00 14 the forward and backwards movement of the hopper car relative to the mining means; (ii) the height of the discharge outlets of the discharge boom above the hopper car; and (iii) the slew of the discharge boom relative to the hopper car; in response to the lateral drift of the conveyor belt relative to the hopper car as sensed by the sensor means.

12. The system defined in any one of the preceding claims wherein the control means is adapted to move the hopper car automatically with the mining means.

13. The system defined in claim 12 when claim 12 is dependent directly or indirectly on claim 2 includes an assembly of a deflector shield mounted to the discharge 20 boom and an ultrasonic pulse generator/sensor mounted to ethe hopper car for determining the relative position of the hopper car and the discharge boom and wherein the control means is responsive to the relative position to actuate drive of the hopper car as required to track the hopper car with the mining means.

14. A system for controlling discharge of a mined °material from a mining means onto a transfer conveyor belt via a hopper car which straddles the conveyor belt substantially as hereinbefore described with reference to the accompanying drawings. Dated this 2 6 th day of July 2000. BHP COAL PTY LTD By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia \\melb-files\home\L~JColeS\Kep\Speci\79903-9g.doc 26/07/00