GB2210081A - Rapid advance mining machine and method - Google Patents

Abstract

A rapid advance mining machine has traditional boom mounted coal cutting means (7, 9) and track means (29) for advancing the machine into a coal face, all mounted on its main frame. At the rear of the machine a rear frame section is provided on which means (61/63) for installing support means for the roof of the mining area is mounted, the rear frame section being telescopically connected to the main frame section of the machine so that as the mining operation is being undertaken at the front of the machine, the rear frame section can be held stationary to install roof support means such as bolts B. Once the roof has been supported the rear frame section can be moved up to the main frame section of the machine. <IMAGE>

Description

RAPID ADVANCE MINING MACHINE AND METHOD This invention relates to a mining machine for rapidly mining material in a continuous manner, and which can be used at the same time to install roof support without having to be withdrawn from the working face.

The invention also relates to a method of mining.

For many years, there has been a demand, especially in the U.S.A., for a mining machine which should be capable of advancing in the order of 100ft. or more in a straight line without need to withdraw from the working face to install permanent roof support. The machine should permit, as part of the mining machine or otherwise, the installation of roof support to protect the machine and its operators. Such support must be permanent rather than temporary and cover the full entry width within 9 feet of the work face, or less.

The machine should also be capable of mining a minimum entry width of 14ft., and should be capable of developing a 90 degree crosscut while permitting roof support to be provided or have an alternative mining system that uses auxiliary devices to provide the crosscuts.

Ideally, the machine should also have a ventilation system, such as a telescopic vent tube which stays within 5ft. of the face, and should minimise dust production by incorporating proven dust control methods. Furthermore, the machine should preferably have a clean-up system which can meet all legal standards regarding coal dust suppression with minimal delays, and the noise level should remain below 84 decibels. It is also preferred that the machine should maintain centerline orientation within a 6in. tolerance, and bit tip speed should not exceed 400fpm, if bits are used.

If bolting is the roof support method, the machine should preferably verify bolt torque and the machine should be adaptable to low coal down to 30ins. The machine should be used with a continuous haulage system, and if the machine is not a full face machine, it should be capable of automatically cycling face activity even if manual activation is required.

The advantage of a machine meeting as many of the aforementioned parameters as possible is that productivity and efficiency are increased, and the working section is made safer, cleaner and less hazardous to health.

Today's mining laws restrict miner operators from advancing the machine operator cab past the last row of permanent roof supports, thus making it necessary for known mining machines to be backed away from the face while permanent roof support is installed. This frequency of place changing results in a loss of production time and an increased probability of accidents occurring due to moving equipment.

The present invention seeks to provide a rapid advance mining machine which will mine coal or other material at a rate competitive with today's production machines while simultaneously installing permanent roof support, and allowing the machine to advance further than the current twenty or so feet, which in turn reduces the frequency of place changing and therefore increases the overall efficiency and production rate.

According to the present invention, we provide a mining machine having means for mining mineral mounted on the machine at its forward end, means for advancing the machine and means mounted on the machine at or towards its rear end for installing support means for the roof of the mined area, the machine including a main frame section supporting the mining means and the machine advancing means, and a rear frame section on which the means for installing support means for the roof of the mined area is mounted, the rear frame section being connected to the main frame section by at least one telescopic arm whereby during a roof support installing operation, a mineral mining operation can also be performed.

The means for installing support means for the roof of the mined area may comprise hydraulic cradles on either side of the machine to raise and fix in position roof support beams. Preferably, however, said means comprises roof drilling means and means for installing roof bolts into holes provided by the drilling means.

Preferably, the machine is designed for forming roadways or headings and the means for mining mineral comprises a continuous mining tool such as a three-piece auger cutter mounted for rotation about a horizontal axis on the front end of a jib which itself is mounted on a turret for pivotal movement about a horizontal axis.

Preferably, the jib is slidably supported on a slide frame extending horizontally adjacent the front end of the machine to enable the auger cutter to be moved transversely across the width of a roadway or heading being mined.

Preferably, an extendable apron is also provided at the front end of the machine and associated with the apron is a primary "circular" conveyor for gathering mining material and transporting it around the rear of the slideway for subsequent discharge onto a rearwardly extending secondary conveyor.

Preferably, two wing plates are associated with the apron, one at each side thereof, and the apron has an extendable front end.

Preferably, the front end of the wing plates are pivotally mounted for movement about a vertical axis.

Preferably, the drilling means includes a drilling frame upstanding from the rear frame section and supporting either three or four drilling masts by means of which three or four holes may be drilled in the roof of the roadway or heading above the rear of the machine while mining is continuing at the front end of the machine, there being a main control console associated with the frame and two machine operator stations, one to either side of the secondary conveyor.

Preferably, the secondary conveyor can be located centrally or to one side of the centre line of the machine depending upon the number of drilling masts on the drilling frame.

Preferably, a buffer frame is provided at least partially to surround the machine operator stations.

Preferably, a plurality of temporary roof supports are also mounted on the rear frame section so as to enable the roof to be supported temporarily in front of the machine operator stations, thus providing a safe location for the operators during the drilling operations.

Also according to the present invention, we provide a method of mining using a single mining machine including the steps of mining mineral at the front of the machine and at the same time installing support means for supporting the roof of the mined area immediately at the rear of the mining operation and while said roof support installation operation is being performed, advancing the front end of the mining machine as necessary relative to the rear of the machine by up to a predetermined amount so that said mining operation can be maintained, and when said roof support installation steps have been completed, moving the rear end of the machine up towards the forward end so that the cycle can be repeated.

Preferably, the method includes the steps of placing temporary roof supports immediately forward of the roof support installation operation, and gathering mined material and removing it through the roof support installation area to the rear of the machine.

Preferably, the roof support installation step comprises drilling holes in the roof of the mined area just to the rear thereof, and then installing roof bolts into said holes.

The present invention is now described by way of example with reference to the accompanying drawings, in which: FIGURE 1 is a side elevation of a mining machine showing the machine in a closed position; FIGURE 2 is an elevation from the other side of the machine showing it in an extended position; FIGURE 3 is a plan view of the machine; FIGURES 4 and 5 are rear elevational views showing two alternative drilling arrangements, and FIGURE 6 is a plan view showing the machine forming a 90" bend in a roadway.

Referring to the drawings, these show a mining machine which can excavate a roadway R whilst simultaneously installing roof bolts B from one central position to prevent the roof of the roadway from collapsing. The roadway excavation size is from 16ft. x 5ft. to a maximum of 20ft. x 9ft., with a maximum forward advance of 4ft.6ins. from one position.

The machine has a cutting element in the form of a shortened continuous miner type jib 1 cutting from roof to the floor in the conventional manner. The jib 1 is powered by a 240 kW continuously rated, water cooled, electric double ended motor 3. A transmission is housed in arms 5 at each end of the motor 3, with the final drive being an epicyclic reduction in each of two outer auger cutters 7. The two outer auger cutters 7 are inclined at a forward angle to give a core free sump and cut, without the use of clearing chains, and a centre auger cutter 9 is supported by its own bearings and is driven through two special large constant velocity joints via a common shaft. A multi-plate torque limiting clutch is housed in a first stage gear wheel in each arm, to ensure overload protection and load sharing of the two transmission trains.The second stage of the transmission uses change gears which allow for the build of different output speeds of between 400 and 65 Oft. per minute.

Phased high pressure water up to 3000 p.s.i. is incorporated into the jib 1 which is mounted for pivoting about a horizontal axis on a pedestal 11, via a robust trunnion pin 13 under the control of a hydraulic lift cylinder 15, which gives the jib the vertical movement.

The hydraulic cylinders 15 are fitted with a linear displacement transducer giving a continuous read out of the jib's vertical position at a main control panel for the machine.

The pedestal 11 in turn is mounted on a substantial jib'support frame 17, via top and bottom slides 19, 21, which allow the jib 1 to traverse across the full face of the roadway R, thus allowing full width cutting to be achieved with the machine in a central position. A further linear displacement transducer is mounted adjacent to the slides and gives continuous read-out of the jib horizontal position at the main control panel. The read-outs of the two transducers give an accurate profile of the roadway dimensions.

Jib traverse is powered by a 35 HP D.C. variable speed electric motor 23 which drives through a high ratio gearbox and finally to the jib through an extremely robust strap link chain 25. A multiplate brake 27 is located on the end of the electric motor 23 which holds the jib 1 in position during its cutting cycle. The machine is advanced in traditional manner on tracks 29 each under the control of a controller (not shown), and control of the drive system is achieved by utilising one of the track drive controllers, thus giving variable speed without having to add a third controller unit. This feature also prevents the machine from being accidentally tracked whilst the jib 1 is being traversed.

A cutter head motor current feed back circuit senses the power at the cutter 7, 9, and reduces the current to the traverse motor 23 and the forward thrust accordingly, when the end of the auger cutters 7, 9 are being used to sump in the heading wall for widening of the heading should it be required.

The machine has a loading system consisting of primary and secondary conveyors 31, 33. The primary conveyor 31 is a single flight 'circular' conveyor having flights 35 capable of handling a surge capacity of 268 cu.ft./min. which is commensurate with the average cutting capacity of the jib which is 133.3 cu.ft./min. equating to 218 cu.ft./min. of loose coal.

The secondary conveyor 33 is a 24" wide 2 5/8" pitch in centre strand chain conveyor, which is driven at the footshaft, thus allowing for an optional fixed or articulating delivery section. The capacity of this conveyor 33 is 350 cu.ft./min. with a chain speed of 340ft./min., such an over capacity ensuring a smooth flow of cut material from the primary conveyor 31 to the secondary conveyor 33. The secondary conveyor 33 can be positioned on either machine centre line (see Figures 3, 4) or offset by 2ft. to the left (see Figure 5). This allows alternative drill patterns for roof support, as illustrated in Figures 4 and 5.

Both conveyors are powered by a common 160 HP continuously rated water cooled electric motor 37 which gives a chain pull of 4 tons nominal for the primary conveyor 31 and 3 tons nominal for the secondary conveyor 33. The whole system is protected by a multiplate overload clutch which is designed to limit the power to 230% of nominal.

The machine has a coal loading/gathering apron 39 with a front blade 41 controlled by hydraulic cylinders, which can raise or lower the blade to the optimum position; the apron also has a float facility which enables the blade 41 to follow any undulations in the floor. A linear displacement transducer is built into one of the cylinders and gives continuous read-out of the apron blade position to assist the operator in accurate horizon control. Two large vertical walls or side plates 43 are fitted to the end of the apron 39 and one of these shrouds the primary conveyor 31 around to its discharge point 45. These walls 43 are pivoted at each end and powered by hydraulic cylinders giving a variable scoop width to the apron 39.

The walls 43 also create a large bunker, which assists the primary loading conveyor 31 during excessive surge loads, should they occur. At its discharge point 45, the primary conveyor 31 overlies the secondary conveyor 33.

Traction for the rapid advance mining machine is provided by two 35 HP D.C. SCR. controlled motors, through a gearbox to a double sprocket output drive. The pads of the tracks 29 are 21 1/2" wide giving a low ground pressure of 21 p.s.i. The undercarriage can either be skids or roller with grease track tension.

The D.C.powered traction gives a positive sumping action, and applied current control offers protection to the traction gearing by the elimination of shock loads.

Variable speed is used during the cutting cycle, with cutter head motor current feedback being provided to reduce traction drive current, and therefore forward thrust. This feature prevents overloading of the cutter head system, and is adjustable to give optimum performance for the machine dynamics and material being cut.

An intermediate and high tramming speed of 30ft./min. and 60ft./min. respectively are available for machine relocation purposes.

Electrical motor overspeed, overcurrent and under voltage protection circuits are built into the controller, with diagnostic L.E.D.'s being provided for the aid of trouble shooting.

A power pack for a hydraulic system consists of 160 HP water cooled continuously rated electric motor 47 driving a commercial shearing P365, 3 section fixed displacement pump 49, delivering a total capacity of 437 litres/min. (115.5 U.S. g.p.m.) at 2000 p.s.i. A header oil tank 51 is situated adjacent to the pump 49 giving a positive pressure head, the main oil tank being built into the machine chassis, combining to give a total capacity of 1365 litres (360 U.S. gallons). The oil tank is a sealed unit with a flexible separator allowing the tank to breathe whilst preventing airborne dust contaminating the oil.

High pressure filters with electrical health monitoring are fitted to all pump sections, with Dosco suction strainers being built into the tank.

The control valves are either directly operated, or I.S. solenoid operated when working in conjuction with a computerised process controller.

The machine has a main chassis of robust two-piece fabrication with track frames being separately bolted-on units, to allow the machine to be stripped down to a reasonable transportable section if required. Built into a front portion of the chassis are two large telescopic arms 53 which support a rear machine frame 55 for drills, temporary roof supports (T.R.S.) and controls. The two arms 53 are powered by hydraulic cylinders, one to each arm, linear displacement transducers being built into the arms, which accurately give a read-out of the machine advance from its position for drilling holes for the roof bolts B. A control valve for the hydraulic cylinders valve has a float position which allows sumping of the machine to be carried out by the tracks during the cutting cycle.

Two inclinometers are secured to suitable points of the chassis, these registering the pitch and roll of the machine.

The rear machine frame 55 is connected to the arms 53 by two large plain spherical bearings 57, with hydraulic cylinders 59 holding the rear frame 55 in the horizontal plane. These spherical bearings 57 allow for an angular movement in the vertical plane of +18e and +80 in the horizontal plane, thus allowing for movement of the machine from roadway centre line, during arduous cutting, whilst the temporary roof support (T.R.S.) 61 is in place and/or when roof bolting is being carried out.

Either three or four heavy duty telescopic drill masts 63 are mounted on the rear machine frame 55 and can be arranged and positioned to suit the drilling pattern and size of roadway, as shown in Figures 4 and 5. Further details of the drill masts are given hereinafter.

A substantial buffer frame, part of which is shown at 65, wraps around two operator stations 67 to afford protection to the machine operators from bunker cars or shuttle cars. Primary controls for the T.R.S. and rear frame advance are located on the buffer frame 65 so that the operator does not have to go beyond the last set of permanently set roof bolts B before the T.R.S. is in position.

Controls for the individual drills are adjacent to each drill mast 63 with a machine master console 67 being located on the right hand side along with a second set of controls 68,69 for locating the rear of the machine laterally for the T.R.S. stells and rear machine frame advance cylinders 53. Manual controls for jib operation and tracks are of the electricl push-button type.

However, normal machine operation is automatic with the cutting cycle being controlled by a computerised micro process controller, thus leaving the operator free to perform the roof drilling and bolting oeprations.

A mobile chest pack may be used for moving the machine about the mine, thus offering the machine driver the optimum vantage point during any manoeuvering operation; an emergency stop button is also located on the chest pack. A stowage point is provided for the unit when not in use.

The T.R.S. is powered by two 160mm diameter hydraulic cylinders, housed in two vertical square section telescopic columns 71, which extend to reach the floor as well as the roof. The T.R.S. complies with the legislation laid down by the U.S. Bureau of Mines, and not only affords protection to the operators but also assists the two hydraulic side stells 69 in maintaining a stationary drill station during drilling operations.

As the flow of mined material from the machine is steady and almost without break, it is envisaged that the secondary conveyor 33 should discharge material into a continuous haulage system of known type, which could also carry ventilation ducting up to the machine.

Alternatively, the secondary conveyor 33 could discharge the material into a bunker car, with shuttle cars being used to remove the material to a main exit conveying system.

Dust is suppressed by means of water jets on the cutters 7, 9. To reduce the amount of water to an absolute minimum, phased water spraying is used, whereby water is only sprayed at the pick whilst that pick is cutting. Furthermore, a Coanda air curtain is positioned behind the cutter jib 1 to form a curtain of air, which acts as a further barrier to prevent the migration of any remaining airborne dust up the heading or roadway. If desired, a flexible ducting carrier can be fitted to the side of the machine which would allow for an extractive ventilation system to be carried forward to the front of the machine, or for a secondary extractive ventilation system to be used.

Having established the desired roadway parameter, the machine operator keys in the roadway width, height and gradients along with the roof bolting pitch, via a computer input keyboard. Once the data has been entered, the procedure need not be repeated, unless any of the input parameters require amendment. Once the roadway parameters have been input, the on-board computer will establish the most efficient cutting cycle.

With the machine positioned correctly in the centre of the roadway, the operator then ensures the machine is in its closed position. The T.R.S. 61 is then raised, and the side stells 69 on the rear machine frame 55 are extended. The operator presses the auto-start button and the computer will then control the cutting aspect of the machine, for one complete bolt pitch advance, thus leaving the machine operator free to commence roof bolting. The roof bolting is a two-man job with one man in each station 65 responsible for the two bolters on their respective sides.

The machine, once a complete cutting cycle has been completed, will then position the jib ready for commencement of the next cycle and stop. When the drill operators have completed roof bolting, both operators are required to press a release button, this ensuring that both have completed the bolting process before the machine is advanced forward for re-start of the next complete cycle. An audible and vision alarm is fitted to ensure that both operators are aware the machine is about to advance the rear machine frame 55 forward to the next re-start position.

If the machine is required just to produce a narrow roadway with a width of between 14 and 16ft., the slideways 19 and 21 could be omitted, and the jib could be fixed in the centre, and telescopic auger cutters could be provided to achieve the variable width.

Drilling holes and installing roof bolts is the traditional means for providing permanent roadway roof support in some countries. As an alternative to this however, traditional roof support may be provided, such as are provided by Hollybank Engineering. In this case, the drilling frames shown in Figures 4 and 5 could be replaced by hydraulic cradles mounted on either side of the machine to place and bolt in position the roof supports.

As can be seen from Figure 6, the rear end of the secondary conveyor 33 can be pivotally connected to the remainder of the conveyor. This assists in using the machine to form bends of at least 900 in roadways, whilst still continuously mining material.

It has been found that by using a rapid advance mining machine as described above, there are considerable savings in time since there is no need to keep having to relocate the machine, and as a result of the extra production time available, there is a considerable increase in production of mined material.

It will of course be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

Claims (17)

CLAIMS:

1. A mining machine having means for mining mineral mounted on the machine at its forward end, means for advancing the machine and means mounted on the machine at or towards its rear end for installing support means for the roof of the mined area, the machine including a main frame section supporting the mining means and the machine advancing means, and a rear frame section on which the means for installing support means for the roof of the mined area is mounted, the rear frame section being connected to the main frame section by at least one telescopic arm whereby during a roof support installing operation, a mineral mining operation can also be performed.

2. A mining machine according to claim 1 wherein the means for installing support means for the roof of the mined area comprises hydraulic cradles on either side of the machine to raise and fix in position roof support beams.

3. A mining machine according to claim 1 wherein said means for installing roof support means comprises roof drilling means and means for installing roof bolts into holes provided by the drilling means.

4. A mining machine according to claim 1, 2 or 3 wherein the means for mining mineral comprises a continuous mining tool mounted for rotation about a horizontal axis on the front end of a jib which itself is mounted on a turret for pivotal movement about a horizontal axis.

5. A mining machine according to claim 4 wherein the jib is slidably supported on a slide frame extending horizontally adjacent the front end of the machine to enable the tool to be moved transversely across the width of a roadway or heading being mined.

6. A mining machine according to any one of claims 1-5 wherein an extendable apron is provided at the front end of the machine and associated with the apron is a primary "circular" conveyor for gathering mined material and transporting it around the rear of the slide frame for subsequent discharge onto a rearwardly extending secondary conveyor.

7. A mining machine according to claim 6 wherein two wing plates are associated with the apron, one at each side thereof, and the apron has an extendable front end.

8. A mining machine according to claim 7 wherein the front ends of the wing plates are pivotally mounted for movement about a vertical axis.

9. A mining machine according to any one of the preceding claims wherein the drilling means includes a drilling frame upstanding from the rear frame section and supporting either three or four drilling masts by means of which three or four holes may be drilled in the roof of the roadway or heading above the rear of the machine while mining is continuing at the front end of the machine.

10. A mining machine according to claim 9 when dependent on claim 6, 7 or 8, and further including a main control console associated with the frame and two machine operator stations, one to either side of the secondary conveyor.

11. A mining machine according to claim 10 wherein a buffer frame is provided at least partially to surround the machine operator stations.

12. A mining machine according to claim 10 or 11 wherein a plurality of temporary roof supports are mounted on the rear frame section so as to enable the roof to be supported temporarily in front of the machine operator stations, thus providing a safe location for the operators during the drilling operations.

13. A mining machine substantially as hereinbefore described with reference to the accompanying drawings.

14. A method of mining using a single mining machine including the steps of mining mineral at the front of the machine and at the same time installing support means for supporting the roof of the mined area immediately at the rear of the mining operation and while said roof support installation operation is being performed, advancing the front end of the mining machine as necessary relative to the rear of the machine by up to a predetermined amount so that said mining operation can be maintained, and when said roof support installation steps have been completed, moving the rear end of the machine up towards the forward end so that the cycle can be repeated.

15. A method according to claim 14 including the steps of placing temporary roof supports immediately forward of the roof support installation operation, and gathering mined material and removing it through the roof support installation area to the rear of the machine.

16. A method according to claim 15 wherein the roof support installation step comprises drilling holes in the roof of the mined area just to the rear thereof, and then installing roof bolts into said holes.

17. A method of mining substantially as hereinbefore describeed with reference to the accompanying drawings.