Mining or in situ disintegration of hard material – Hard material disintegrating machines – Sidewall-working
Patent
1985-03-11
1988-04-26
Leppink, James A.
Mining or in situ disintegration of hard material
Hard material disintegrating machines
Sidewall-working
299 33, 299 54, E21C 2926, E21D 2300
Patent
active
047400374
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to continuous mining machines.
BACKGROUND ART
With reference to FIG. 1 of the drawings, the most common method of cutting coal and supporting the roof used in Australian coal mines for roadway driveage uses timber props 10 set at each side of the roadway 11 beneath or adjacent to steel straps, wooden bars or similar devices 12 held to the roof by roof bolts 13. The straps or bars 12, are usually supplied cut to the required length to suit the roadway width and usually with pre-drilled holes at the desired roof bolt positions. Props 10 are usually supplied over-size, cut to length on site and installed by hand using wooden wedges to tighten them in position. Roof bolts 13 are steel rods 14 of the required length supplied with an anchoring device 15 (most commonly a resin type of glue) to fix one end in the rock, and a threaded outer end to take a nut 17 and steel washer 16. Their action is to clamp the layers of roof strata together to form a strong beam and/or to suspend layers of broken strata from more stable higher layers.
To install a roof bolt, a small hole (usually of the order of 27 mm diameter) is drilled into the rock to the length of the bolt. A cartridge containing a two part resin mix is then inserted into the hole and pushed to the end using the bolt itself. The bolt is then spun for a few seconds. This has the effect of breaking-up the cartridge and mixing the resin parts. Because of the fast-setting nature of the resin, the nut can be tightened almost immediately to bear against the roof strap, bar, etc., and a degree of tension is thus applied to the bolt. The same machine is normally used to drill the hole, install the bolt and tighten the nut using various adaptors fitted to the chuck. During installation of the first two bolts the strap, bar, etc., is normally held in position by two hydraulic jacks attached to the mining machine. The drilling machines are commonly hand held machines supported on an extendable leg, but can be attached to the mining machine.
It should be noted that there are wide variations in the system described above in number, type, and spacing of supports and bolts, types of bolt anchoring systems, and angle at which bolts are installed. These variations depend on a number of factors, notably surrounding rock types and strengths, roadway heights and widths, and stress conditions. However, the basic system is the same in the majority of cases.
The machine which actually cut the coal, the continuous miners, come in a variety of makes and models, but are all basically the same in principle. The main frame which supports the working parts and contains motors, hydraulic pumps, tanks, controls, etc., is mounted on a crawler track assembly for mobility. At the top of the front of the machine is mounted the cutting head which has rotating drums and/or chains fitted with cutter picks to cut the coal. In the current range of machines the head is usually referred to as fixed which means it cuts a set width although it can be raised and lowered to cut the desired height. The cut coal falls to the floor where it is picked up by a loader apron fitted with some type of gathering device which guides the coal into the centre of the machine. From here the coal is collected by a scraper conveyor which runs through the centre of the machine to a luffing and slewing jib which enables the coal to be loaded into mobile vehicles (shuttle cars) behind the miner for transportation to the conveyor belt system.
Because the machiens can only cut approximately their own width at one time it is necessary to move them around to cut the full width required. Also, in order to cut forward the whole machine has to tram into the face. It therefore follows that while coal cutting operations are in progress the whole machine is almost continuously moving in a confined area. This makes it very hazardous, if not impossible, to work alongside the machine while it is cutting and it is in this confined area that the roof support operations have to be carried out. As a
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Deamer Charles R.
Eager Donald T.
Keene George H.
Kelly Donald A.
Mason Norman B.
Bagnell David J.
Kembla Coal & Coke Pty. Limited
Leppink James A.
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