Patent Application
20130187436
This application claims priority from Australian Patent Application No. 2011902843, the contents of which are incorporated by reference.
The present invention relates to the operation of a caving system such as, for example, a long wall top coal caving (LTCC) system.
An LTCC system has a tailgate, a main gate and a cutter that travels between the main gate and tail gate, to cut coal from the long wall. The system also includes front and rear armoured conveyors that travel beneath overhead shields, from the tailgate end, to deliver coal to a beam stage loader positioned adjacent the main gate. Each conveyor runs along a respective front or rear pan line and is driven by two motors, one at the tail gate end and one at the main gate end. The front conveyor carries coal cut by the cutter while the rear conveyor carries caved coal.
The shields protect the various components of the system and support the roof of the mine. The shields provide a continuous protective canopy over the length of the long wall, which may be up to 300 metres in length. Special buttress, gate and transition shields are provided toward each end of the system. The remaining run of face shields allow for caving, which is a distinguishing feature of the LTCC system. In particular, the shields are provided with a caving canopy and a slide door. The canopy can be lowered and the slide retracted to allow coal to cave onto the rear conveyor, after which the canopy can be returned to its original position.
With existing LTCC systems, the caving operation is conducted manually, on each individual shield in turn. After each cutting cycle, the shields are moved forward, the caving is then completed and the rear pan line is pulled forward in line with the shields, ready for the next cutting cycle. As may be appreciated, the entire process is relatively time consuming and the output of coal during the caving cycle varies dramatically. The volume of coal output from the caving cycle is also considerably less overall compared to the coal extracted during the cutting cycle.
It is an object of the invention to provide an improved coal extraction technique.
In one broad aspect, there is provided a shield control method including controlling a shield of a coal caving system to automatically open a door associated with a rear canopy of the shield to allow coal to cave onto a conveyor.
Preferably, the door is opened responsive to a position of a shearer of the system.
Preferably, doors of adjacent shields along a length of the system are sequentially opened and closed during a first cycle which follows a first pass of the shearer.
Preferably, the rear canopy is retracted to increase caving.
Preferably, a rear canopy and door of one or more adjacent shields are sequenced to open and close along the length of the system so that groups of adjacent shields simultaneously undergo a coal caving operation so as to allow an increased amount of coal to cave onto the conveyor.
Preferably, the caving operation propagates along the length of the system by virtue of selective opening and closing of the shields.
Preferably, the caving operation is performed during a second cycle, ahead of a second pass of the shearer.
In accordance with one broad aspect, there is provided a method of operating a long wall top coal caving system which includes a front and rear conveyor extending beneath shields which include canopies and associated caving doors, wherein the caving doors are sequenced to automatically open in a first cycle to regulate limited caving onto the rear conveyor.
Preferably, groups of canopies are opened selectively during a second cycle to allow increased caving onto the rear conveyor.
Preferably, the system includes a shearer which cuts a web distance into the long wall to deliver coal to the front conveyor, wherein the shearer is operated to cut a web in two passes, the first pass cutting a greater portion of the web and the second pass cutting the remaining portion of the web.
Preferably, the first cycle of the caving follows the first pass of the shearer.
Preferably, the second pass of the shearer follows the second cycle.
In another broad aspect, there is provided a long wall top caving system including a front and rear conveyor extending beneath shields which include canopies that are operable to allow caving onto the rear conveyor, the system further including a controller to automatically open the canopies in accordance with the above described method.
In another broad aspect, there is provided a controller for a long wall top coal caving system, the caving system including a front and rear conveyor extending beneath shields which include canopies, wherein the controller includes a processor configured to automatically to open the canopies to allow caving onto the rear conveyor.
Preferably, the controller is in communication with a plurality of sensors from one or more components of the long wall top coal caving system, wherein the processor is configured to:
receive one or more feedback signals indicative of operation of the one or more components;
determine, based on the one or more feedback signals, if the canopies are to be opened; and
in response to a positive determination, actuate one or more drives associated with the canopies to allow caving onto the rear conveyor.
Preferably, the caving system includes a shearer, wherein the one or more sensors include a shear position to detect a position of the shearer and to transfer a position signal indicative of a position of the shearer to the controller, wherein the processor is configured to compare the position of the shearer against one or more position thresholds, stored in memory of the controller, to determine if one or more of the canopies require opening.
Preferably, the processor is configured to determine, based on the position of the shearer, if the shearer has passed one or more of the canopies which are open, wherein in response, the processor actuates a drive of the canopy to close the respective one or more canopies accordingly.
Preferably, in response to determining the position of the shearer, the controller actuates one or more conveyor drives to cause displacement of a respective one or more portions of the front and/or rear conveyor toward a long wall which the shearer is cutting.
Preferably, each canopy includes a flipper actuated by a flipper drive which is urged against the long wall in a deployed position, wherein in response to determining that the position of the shearer satisfies a first position threshold, the flipper drive is actuated by the processor to move the flipper to a retracted position.
Preferably, in response to determining that the position of the shearer satisfies a second position threshold, the flipper drive is actuated by the processor to move the flipper to the redeployed position and urged against the long wall.
Preferably, the processor is configured to actuate a plurality of canopy drives associated with a rear canopy and door of one or more adjacent shields which are sequenced to open and close along the length of the caving system so that groups of adjacent shields simultaneously undergo a coal caving operation so as to allow an increased amount of coal to cave onto the conveyor.
The invention is more fully described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
Referring firstly to
A transition shield 10 and special end gate shields 11 are located adjacent a tail gate (TG) 12 of the extraction arm 2 and cover a rear tail gate drive 13 and front tail gate drive 14, respectively.
A shearer 15 is also located adjacent the tail gate end 12. The shearer 15 includes a shearer arm 16 which supports two cutter drums 17, 18 on respective ranging arms 19.
In operation, the shearer moves to the left, as viewed, and cuts into the long wall 9 as it travels away from the tail gate end 12 on a first pass. As illustrated in
Ideally, the first pass of the shearer 15 serves to cut a large portion of a web of coal from the long wall 9. After the shearer 15 has passed, individual canopies 6 and slide doors 7 are automatically operated by a controller (not shown) in a first cycle, to regulate a limited flow of coal which caves onto the rear conveyor carried by rear pan line 5. The caved coal provides a relatively constant but lesser volume of coal compared to that generated by the shearer 15. Both the caved coal and the cut coal are subsequently combined so that the extraction arm 2 provides a relatively constant high flow output.
In
As can be seen, the front pan line 4 has been progressively snaked in behind the shearer 15 to lie immediately adjacent the long wall 9, in preparation for the shearer 15 to return back toward the tail gate 12, on a second pass of the long wall 9.
The caving cycle has also been completed and all of the coal generated from both the shearer on the first pass and the caved coal from the first cycle is delivered along the pan lines 4 and 5 to a beam stage loader 27.
The canopies 6 are then operated in a second cycle in groups, to selectively cave in a direction back toward the tail gate 12. One such group is indicated by reference numeral 28 in
Once the second cycle has been initiated, the shearer 15 commences its second pass cutting into the long wall to remove the remaining portion of the web.
Since the canopies are allowed to cave as a group, the volume flow of coal carried along the rear pan line 5 increases substantially, which helps supplement the reduced volume along the front pan line 4.
The rear pan line 5 is snaked in behind the leading group 28 as the caving moves back toward the tail gate end 12, as illustrated more clearly in
After the second cycle is complete, the shearer 15 continues to move to the right, as viewed, and cuts into the long wall 9 while the front pan line 4 is pushed against the long wall 9. The tail gate drives 13,14 are also moved forward so that the front pan line 4 and rear pan line 5 are in a straight configuration, when the shearer 15 finally stops at an end of travel position adjacent the tail gate 12. In that position, the end gate shields 11 are stepped forward, whereby the system 1 is again ready for another cutting and caving sequence.
As may be appreciated from the above, supplementing the cut coal of each pass with low flow and then high flow caving helps to regulate and unify the total output to the coal extraction arm regardless of whether the shearer is on the first pass or the second pass and this has considerable operational advantages. Also, separating the cutting process into two stages or passes means that load bearing requirements of the various machinery components is considerably less than if the entire web was cut at the one time. As such, the conveyors, drive motors and pan line construction can all be rated for lower operational requirements, which can lead to significant cost savings.
In addition, it should be noted the automated caving of the above described system 1 all occurs downstream of the shearer 15, in so far as the caving occurs between the shearer 15 and the tail gate 12. This is significant in that the entire extraction arm 2 may be subject to a general air flow in a direction from the main gate 20 to the tail gate 12, for dust control purposes, which means personnel working at the shearer 15 will be protected from dust generated by the caving process.
It should also be appreciated that by automating the caving cycle considerable efficiencies have been achieved compared to the prior manual caving technique. Manual caving can take about 3 minutes per shield whereas the automated system can cave at a rate of up to 35 seconds. This significantly improves operational output of the extraction arm.
By way of further explanation in relation to the caving process described above, reference is now made to
In the position shown, the conveyor 36 has been moved forward relative to the pontoon 31, ready for a new cutting cycle at the face 35.
The shield 3 also includes a rear canopy 6 which protects the rear panline 5 and rear conveyor 37. The rear canopy 6 is moveable via a hydraulic cylinder 38 between an elevated position, as shown, and a retracted position where coal is allowed to cave onto the conveyor 37. The rear canopy 6 has an associated slide door 7 which is extended to stop flow of coal caving onto the conveyor 37 but which can also be retracted to allow a lesser amount of caving onto the rear conveyor 37.
During the first cycle described above, the slide door 7 of each individual shield 3 is selectively opened to allow a limited amount of coal to cave onto the conveyor 37. During the second cycle, the rear canopy 6 can also be retracted to increase the volume of coal being caved onto the conveyor 37. To stop the flow of coal, the rear canopy 6 would then be elevated back to the position shown and the door 7 subsequently closed.
After the caving process is finished, the rear panline 5 and conveyor 37 are moved in toward the pontoon 31 to allow the overall shield 3 and system 1 to walk forward in a direction from right to left, as viewed, during each cutting cycle. For that purpose, a piston 39 and chain 40 are used to retract the rear conveyor 37 to a position adjacent the pontoon 31, as shown in
Referring now to
The caving sequence described is in a direction away from the main gate, in advance of the shearer 15, so the shield #6 will be the first shield to cave. It should be appreciated that the system 1 includes a controller and sensors (not shown) which continually monitor the positions of the shield doors and rear canopies. The controller, also effects movements of the door and canopy of the various shields between selected positions for predetermined periods of time during a coal caving operation. To that end, the door 7 associated with shield #6 is retracted from a position 100% extended to 0% extended, which may occur over a 3 second interval, to a position shown in
The rear canopy 6 is then moved from the position of about 85% extended, which corresponds to the position shown in
In
The caving sequence described above is propagated along the shields 3 toward the tail gate until all of the shields have completed a caving operation. The caving sequence has been described by reference to one shield finishing a caving operation while an adjacent shield is simultaneously undergoing caving and a third shield is commencing a caving operation. However, a greater number of shields can be sequenced together so to form a larger group of simultaneously caving shields. A caving sequence for a group of, for example, six shields is described in the Example below.
In either case, however, it is preferred the relevant shields 3 have the capacity to cave in order to meet the timing requirements above. In some cases, the rear canopy 6 may need to be raised and lowered a number of times to crush and loosen coal above the shield 3 to facilitate further caving or the slide door 7 may need to be moved in smaller increments if the caving operation is spread over a larger number of shields 3. Accordingly, each shield should, for example, have a caving cycle specification that allows:
As will be clear from the above, multiple doors and/or canopies are sequenced to open as a group ahead of the shearer 15 as it moves from the main gate 20 to the tail gate 12. This corresponds to a lesser amount of coal being cut by the shearer 15 and transferred along the front conveyor so a larger amount of coal needs to be caved onto the rear conveyor 37 to normalise output to the beam stage loader 27. When the shearer 15 is taking a larger cut of coal as it moves from the tail gate 12 to the main gate 20, a much lesser amount of caved coal is required so only the doors 7 of the relevant shields 3 need to be opened individually, without moving the associated rear canopies 6, in a cycle which follows progress of the cutter.
Referring to
In a preferred form, the controller 1200 has stored in memory 1220 computer executable instructions representing a computer program which, when executed by the processor 1210, can autonomously control at least some of the drives 1280 via feedback signals received from the sensors 1270.
Referring to
The controller 1200 is also in electrical communication with the drives 1280 of components of the system including front tail gate drive 1305, rear tail gate drive 1315, front panline and conveyor drive 1325, rear panline and conveyor drive 1335, shearer driver 1345, one or more canopy drives 1355, one or more slide door drives 1365, one or more slide door sensors 1370, one or more flipper drives 1375, one or more flipper drives 1380, and one or more shield advancement drives 1390.
In operation, the controller 1200 maintains a direction variable in memory to indicate the cycle pass of the shearer. Initially, the direction variable is set to the first cycle, wherein the shearer 15 moves to the left, as previously discussed in relation to
The feedback signal received from the shearer sensor 1350 is indicative of the position of the shearer 15. The processor 1210 of the controller 1200 compares the shearer position against a number of thresholds stored in memory 1220 in order to begin actuation of appropriate flipper drives 1375, wherein appropriate flippers 8 are retracted accordingly. The controller 1200 receives feedback signals from the flipper sensors 1380 in order to control the respective flipper 8 movement.
Once the processor 1210 determines that the current position of the shearer 15 has passed the location of particular shields 3, the appropriate shield advancement drives 1385 are actuated by the controller 1200 to cause the respective shields to move forward. The controller receives a shield advancement signal from the shield advance sensors 1390 indicative of the advance of each respective shield in order to control the shield advancement. In addition, the flipper drives 1375 of the flippers 8 of the advanced shields 3 are actuated by the controller 1200 to cause the respective flippers 8 to be redeployed. The controller 1200 receives a flipper deployment signal from each flipper sensor 1380 of a flipper 8 in the process of being redeployed in order to control the redeployment. Additionally, after the shearer 15 has passed, individual canopy drives 1355 of canopies 6 and slide door drives 1365 of slide doors 7 are actuated by the controller 1200 to regulate the limited flow of coal which caves onto the rear conveyor carried by the rear pan line 5.
Once the shearer 15 has reached the main gate, the second cycle is initiated, wherein the processor 1210 updates the direction variable in memory 1220 and the processor 1210 of the controller 1200 determines a group of canopies which are to be actuated in order to increase the caving. Upon determining the group of canopies, the controller 1200 transfers a plurality of signals to a plurality of canopy drives 1360 to be actuated as a group accordingly. The controller receives canopy signals from the canopy sensors 1360 of the actuated canopies to control the actuation thereof. Preferably, the controller 1200 also transfers a plurality of signals to the slide door drives 1365 which correspond to the determined group of canopies in order to control the retraction and extension thereof to control the flow rate. The controller 1200 receives slide door signals from the slide door sensors 1370 in order to control the actuation of the slide doors 7.
Once the second cycle has been initiated, the shearer 15 commences its second pass which can be controlled by the controller 1200 transferring a control signal to the shearer drive 1345, although as stated above, this is not essential as another control system may control the movement of the shearer.
As the shearer 15 continues to move and cut into the long wall 9, the appropriate front pan line and conveyor drives 1325 are actuated by the controller 1200 accordingly such that the front pan line 4 is pushed against the long wall 9. The controller controls the actuation of the appropriate front pan line and conveyor drives 1325 via receiving signals from the front pan line and conveyor sensor 1330. The controller 1200 actuates the tail gate drives 13, 14 so that the front pan line 4 and rear pan line 5 are in a straight configuration, wherein signals from front and rear tail gate sensors 1310, 1320 are used as feedback to control the actuation accordingly. As the shearer 15 passes, the controller 1200 actuates the rear pan line and conveyor drive 1335, wherein signals received from the rear pan line and conveyor sensor are used to control actuation thereof. Once the shearer 15 reaches the tail gate, the controller 1200 actuates the end gate shield drives 1385 which cause the respective end gate shields to step forward.
It will be appreciated that the input device 1230 of the controller 1200 can enable a user to provide input commands to control the operation of the system. The input device 1230 may be provided in the form of a keyboard or various buttons of a control panel. The output device 1240 of the controller 1200 can be provided in the form of a display screen.
A specific example of the LTCC system cutting and caving cycle is provided below.
1. General Information
1.1 Coal Block to be Mined
1.2 Equipment
1.2.1 Shields
1.2.2 Conveyors
1.2.3 Shearer
2. Overview of Cut Cycle
3.1 Shield Advance Methodology
3.2 Front Armoured Face Conveyor (FAFC) methodology
3.3 Caving Methodology
3.4 Rear Armoured Face Conveyor (RAFC) Methodology
3. Detailed Cut Cycle
4.1 Shearer at TG Ready to Start Cutting to the MG
4.2 Shearer Starts Cutting from TG to MG into a 70% Web
4.3 Shearer Cuts into the MG Electrical Stop
4.4 Shearer Carries Out MG Clean up Shuffle and then Starts Cutting from MG to TG into a 30% Web
4.5 Shearer Cuts into the TG Electrical Stop and then Completes the Clean up Shuffle
5. Controller—PMC-R Special Requirements
5.1 Front Flipper Function
5.2 Caving Function
5.2.1 High Flow Caving Function
5.3 FAFC Pan Push Function
5.4 Shield Advance Function
5.5 BSL Push Function
5.6 BSL Current Control Function
5.7 RAFC Pan Pull Function
5.8 Parameter Password Protection
5.9 Water Sprays
5.10 Additional Features Required
5.10.1 Cycle Count Software
5.10.2 Operator Proximity Detection
5.10.3 Unplanned Movement Protection
5.10.4 Button Press Record
5.5 Shearer Special Requirements
The above described invention has been described by way of non-limiting example only and many modifications and variations may be made without departing from the spirit and scope of the invention.
1. Longwall top coal caving (LTCC) system
2. Extraction arm
3. Shield
4. Front panline
5. Rear panline
6. Rear canopy
7. Slide, door
8. Flipper
9. Longwall
10. Transition shield
11. End gate shield
12. Tail gate (TG)
13. Rear tail gate drive
14. Front tail gate drive
15. Shearer
16. Shearer arm
17. Cutter drum
18. Cutter drum
19. Ranging arm
20. Main gate (MG)
21.
22. Front main gate drive
23. Rear main gate drive
24. Buttress shield
25. Shield
26. Transition shield
27. Beam stage loader
28. Group
29.
30. Main canopy 30
31. Pontoon
32. Hydraulic legs
33. Roof
34. Mine
35. Face
36. Front conveyor
37. Rear conveyor
38. Hydraulic cylinder
39. Piston
40. Chain
1200. Controller
1210. Processor
1220. Memory
1230. Input device
1240. Output device
1250. Control Interface
1300. Control system
1310. Front tail gate sensor
1320. Rear tail gate sensor
1325. Front pan line and conveyor drive
1330. Front pan line and conveyor sensor
1335. Rear pan line and conveyor drive
1340. Rear pan line and conveyor sensor
1345. Shearer drive
1350. Shearer sensor
1355. Canopy drive(s)
1360. Canopy sensor
1365. Slide door drives(s)
1370. Slide door sensor(s)
1375. Flipper drive(s)
1380. Flipper sensor(s)
1385. Shield advancement drive(s)
1390. Shield advancement sensor(s)
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011902843 | Jul 2011 | AU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU2012/000286 | 3/19/2012 | WO | 00 | 2/20/2013 |
