GB2193987A

GB2193987A - Mineral cutting method and apparatus

Info

Publication number: GB2193987A
Application number: GB08716282A
Authority: GB
Inventors: William Summers
Original assignee: Pitcraft Summit Ltd
Current assignee: Pitcraft Summit Ltd
Priority date: 1986-08-19
Filing date: 1987-07-10
Publication date: 1988-02-24
Also published as: GB2193987B; GB8620137D0; GB8716282D0

Abstract

A mineral cutting method comprises advancing an auger 2 into the mineral; providing water-jet means 5 on a leading end 6 of a leading section 7 of the auger 2, to direct a water-jet 8, 8A forwardly, adding auger sections as the resulting bore is advanced and thereafter progressively removing auger sections, providing a high pressure water supply to the water-jet means, and rotating the auger. <IMAGE>

Description

SPECIFICATION Mineral cutting method and apparatus This invention relates to a mineral cutting method and apparatus either for the winning of a mineral such as coal, potash etc., located in seams, or for the driving of underground roadways, headings, tunnels, shafts, boreholes etc.

Conventionally, the above minerals are won by either of two techniques-the longwall technique (using a shearer type mining machine, a trepanner type mining machine, or a plough)-or the room and pillar technique (using a continuous mining machine).

In difficult seam conditions however, an augering technique has been practised in the U.S.A and is described in Colliery Engineering, March 1961, pages 112-114, where a leading end of the auger was provided with three 1200 arms carrying carbide cutter tools and also with a central, pilot tool, with the auger being lengthened as winning progressed, by the addition of 5ft length auger sections.

However, the technique was not acceptable in U.K. coal mines due, it is believed, to the potential for explosions and the high level of dust created, whilst significant down time is involved, principally in the removal of the sections. As coal etc., seams are most commonly located in horizontal planes, augering is similarly effected most commonly in a horizontal direction, and consequently a feed unit is required not only to feed the auger forward along the bore being produced, but also to power the cutting tools into the blind bore end, and of course after completion of the bore, to retract the auger-such feed unit being in addition to a rotary unit to rotate the auger, to convey the cut mineral along, and from, the bore.The requirement for a power feed unit imposes limits on the length of auger that can be assembled and operated, and a relatively short, 100 ft length auger is typical.

In more recent times, attention has again focussed on so-called water-jet cutting (where no mechanical cutter tools are involved) but due to various problems this has not been exploited commercially to any great extent and so-called water-jet assisted cutting (where a combination of water jets and mechanical cutter tools are employed) for mineral winning operations and also roadway driving operations, which has been exploited commercially.

The object of the present invention is to provide an improved mineral cutting method and apparatus over previous proposals.

According to a first aspect of the present invention there is provided a mineral cutting method comprising: (a) advancing an auger having a longitudinal axis and built up from individual auger sections releasably secured together end-to-end into the mineral; (b) providing water-jet means on a leading end of a leading section of the auger, which water-jet means is adapted to direct a waterjet forwardly, and parallel or generally so, to the longitudinal axis of the auger; (c) adding auger sections to the lrailing end of the auger as the resulting bore is advanced by the water-jet means, and feeding the auger along the bore as bore advance proceeds; (d) when a bore of desired length has been produced, retracting the auger from the bore with progessive removal of the auger sections from the trailing end of the auger as retraction progresses;; (e) providing a high pressure water supply to the water-jet means, and (f) rotating the auger to convey cut mineral from the bore.

According to a second aspect of the invention there is provided apparatus for carrying out the above defined method, comprising: (a) an auger having a longitudinal axis and built up from individual auger sections releasably secured together end-to-end; (b) water-jet means provided on a leading end of a leading section of the auger, which water-jet means is adapted to direct a waterjet forwardly, and parallel or generally so, to the longitudinal axis of the auger; (c) means to supply high pressure water to the water-jet means; (d) feed means to feed the auger along the bore, and subsequently to retract the auger from the bore, and (e) rotary power means to rotate the auger to convey the mineral from the bore.

Thus, by operating the method and apparatus of the invention, the possibility of sparking, and explosion during the mining of coal is totally eliminated, due to the absence of mechanical tools, whilst the presence of water also has a beneficial effect in the supression of whatever dust is generated with a resultant environmental improvement. Furthermore, because mineral cutting and hence bore advance is by a water-jet, no power feed of the auger in the conventional sense by the feed means is required, so that for the same auger length, the feed means may be of reduced rating, or alternatively the same feed means may satisfactorily feed a longer length auger of e.g., 200 ft.

However, the economics of using high water pressures e.g., 10,000 p.s.i., demand efficient water usage, which means small diameter nozzles, which require a clean water supply to avoid repeated nozzle blockage, and the latter problem is solved by the proposal described in our co-pending GB Patent Application No.8620136 filed contemporaneously with the present Application.

It will be appreciated however, that in the winning of a mineral seam the auger diameter should ideally approximate to the seam thick ness, and hence a wide range of auger diameters would be required, to cater for various seam thicknesses. However, with seams of 6ft thickness and greater, the auger sections become too large and/or awkward to handle in mine conditions. Hence to win a lOft thick seam, a 4ft diameter auger say would fir st be used to remove an upper part of the seam to be followed by a lower part, requiring the additional cost/complication of a raisable and lowerable feed bed arrangement for the auger sections. Furthermore, winning operations are possible over only some 40% of the total time expended, due to removal time of the auger sections from a completed bore when no mineral winning at all is being effected.

Therefore, in accordance with an enhanced method of the invention, the auger is provided with first water-jet means mounted on a leading end of a leading section of the auger and adapted to direct a water-jet forwardly and parallel or generally so, to the longitudinal axis of the auger, and is also provided with sec ond water-jet means adapted to direct waterjet(s) laterally and/or rearwardly. The second water jet means may be operative only after completion of the bore, to ream out the bore during withdrawal of the auger from the bore.

Alternatively, the reaming effect may of course be required at other times.

Similarly, apparatus for carrying out the enhanced method of the invention is additionally provided with second water jet means mounted on one section of the auger and adapted, e.g., during auger withdrawal, to di- rect water-jet(s) laterally and/or rearwardly e.g., to ream out the bore. The second water jet means Fnay be mounted either on the leading auger section, or on an adjacent auger section, or on any other auger section.

Thus, by employing the enhanced method and apparatus of the invention, the quantity of won mineral is no longer confined to the volume represented by the auger diameter and length, but is substantially extended beyond this, by enlargement of the bore from its initial auger diameter during the reaming action. Furthermore, the cutting method is now bi-directional, in that mineral winning is effective during both advance and withdrawal of the auger.

Yet again, the reaming action of the second water jet means is also effective in infusing and weakening the surrounding strata, which eases subsequent penetration of the auger into the mineral, in the course of producing the next, adjacent, parallel bore(s).

In the winning of a mineral seam, the auger may be advanced along the mid-plane of the seam, or at the level of a mine floor adjacent the seam. In the former case, a 6ft thick seam may for instance be won in one pass, of a 3ft diameter auger, with firstly the roof coal falling and then the coal at both lateral sides or wings, and beneath the auger - assuming the seam lies in a horizontal plane. In the latter case, phased operation e.g., over 1800, of the second water-jet means is preferred, firstly for economic use of water and secondly to avoid degradation of the mine floor, and consequently the apparatus is preferably provided with phasing means e.g., a cam arrangement.

Conveniently, each auger section may comprise an inner barrel part, with an auger vane secured e.g., by welding, around the outer periphery of the barrel part.

Furthermore, as the auger would usually be operated horizontally, then in accordance with another preferred feature, the auger vane is provided with a rim extending around its peripheral edge, to spread area loading of the auger on the mine floor, and hence to eliminate any unwanted penetration of the auger into the floor.

The high pressure water supply is preferably provided by at least one water pipe or hose.

Preferably, a single pipe or hose is provided and if, in accordance with the enhanced apparatus, first and second water jet means are provided, a changeover valve, e.g., of a pressure sensitive type, may be employed to switch the supply between the first and second water jet means.

The feed means is preferably hydraulically powered and may incorporate an hydraulic motor and an endless chain drive. The feed means may comprise a pairof spaced-apart, parallel slide tracks mounted on a support structure and conveniently the latter is provided with adjustable levelling legs, e.g. of a hydraulic piston and cylinder kind. A carriage is preferably displaceable along the slide tracks, on which carriage the rotary power means is supported, with the carriage attachable to the endless chain drive.

The rotary power means is also preferably hydraulically actuated, incorporating an hydraulic motor, with a drive connection between the motor (possibly with an interposed gearbox) and the trailing auger section.

The method and apparatus in accordance with various aspect of the present invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic plan view of the forward end of apparatus in accordance with the invention; Figure 2- corresponds to Figure 1, but shows the rearward end; and Figure 3 is an enlarged view of a portion of an auger section of Figures 1 and 2.

In the drawings, the apparatus 1 comprises an auger 2 having a longitudinal axis 3. The auger 2 is progessively built-up during advance of the bore 4 from individual auger sections releasably secured together end-to-end by any convenient means, e.g. bolts. A first water-jet means 5 in the form of a plurality of water discharge nozzles is provided in a head 6 at a leading end 8 of a relatively short length leading secion 7 of the auger 2, which water-jet means 5 is adapted to direct a water-jet forwardly, and parallel as indicated at 8 or generally so, as indicated at 8A, to the longitudinal axis 3 of the auger 2. Behind the leading section 7 are secured a plurality of relatively long length sections 9 serving to extend the overall length of the auger 2 as they are progressively attached as the bore 4 is lengthened.Initial location of one auger section with respect to the next auger section may be by way of a spigot 10 penetrating an appropriate receiving socket. Each auger section 7, 9 comprises a hollow inner barrel part 11 around which is welded a helical vane 12 with a rim 13 (Figure 3) extending around its peripheral edge.

The auger 2 is additionally provided with second water jet means 14, also in the form of a plurality of water discharge nozzles, mounted on one auger section 9 and adapted, during auger withdrawal, to direct water-jet(s) laterally and/or rearwardly as indicated at 15.

The high pressure water supply is preferably provided by at least one water pipe or hose, which is not shown, but a suitable arrangement is described in our co-pending GB Patent Applicafion No. 8620136.

Afeed means 16 to feed the auger 2 along the bore 4 incorporates an hydraulic motor 17 and an endless chain drive 18, serving both to advance and to retract the auger 4. The feed means 16 comprises a pair of spaced-apart, parallel side tracks 19 mounted on a support structure 20 provided with adjustable, piston and cylinder levelling legs 21. A carriage 22 is displaceable along the slide tracks 19, on which carriage 22 a rotary power means 23 is supported, with the carriage 22 attached by an arm 24 to the endless chain drive 18. The rotary power means 23 is constituted by an hydraulic motor, with a drive connection between the motor and the trailing auger 9, with an interposed gearbox 25.

During advance of the auger 2 along the bore 4, the bore diameter approximates to the auger diameter, the mineral being loosened/broken by th e action of the waterjets 8, 8A, and the loosened/broken mineral being retracted along the bore 4 by the action of the helical vanes of the auger sections, with successive auger sections 11 being added at the support structure 22 as and when required. When the limit of advance of the auger 2 has been reached, the water supply is switched from the first water-jet means 6 to the second water-jet means 14. This brings about a reaming effect, enlarging the bore from the initial diameter indicated at 4 to the enlarged diameter indicated at 4A, with the mineral loosened/broken by the second water-jet means 14 again being retracted along the bore by the helical vanes 12, and progressive enlargement of the bore from its leading end remote from the support structure 22 occurs, as sections 11 are progressively removed during retraction of the auger 2.

Claims

1. A mineral cutting method comprising: (a) advancing an auger having a-longitudinal axis and built up from individual auger sections releasably secured together end-to-end into the mineral; (b) providing water-jet means on'a leading end of a leading section of the auger, which water-jet means is adapted to direct a waterjet f orwardly, and parallel or generally so, to the longitudinal axis of the auger; (c) adding auger sections to the trailing end of the auger as the resulting bore is advanced by the water-jet means, and feeding the auger along the bore as bore advance proceeds; (d) when a bore of desired length has been produced, retracting the auger from the bore with progessive removal of the auger sections from the trailing end of the auger as retraction progresses;; (e) providing a high pressure water supply to the water-jet means, and (f) rotating the auger to convey cut mineral from the bore.

2. A method as claimed in Claim 1, wherein the auger is provided with first water-jet means mounted on a leading end of a leading section of the auger and adapted to direct a water-jet forwardly and parallel or generally so, to the longitudinal axis of the auger, and second water jet means adapted to direct water-jet(s) laterally and/or rearwardly.

3. A method as claimed in Claim 2, wherein the second water jet means is operative only after completion of the bore to ream out the bore during withdrawal of the auger from the bore.

4. A method as claimed in Claim 3, wherein in the winning of a mineral seam, the auger is advanced along the mid-plane of the seam.

5. A method as claimed in Claim 3, wherein in the winning of a mineral seam, the auger is advanced at the level of a mine floor adjacent the seam.

6. A method as claimed in Claim 5, wherein phased operation of the second water-jet means is effected.

7. A method as claimed in Claim 6, wherein phasing is over 1800.

8. A method as claimed in any preceding Claim, wherein the auger is operated horizontally.

9. Apparatus for carrying out the method of Claim 1, comprising: (a) an auger having a longitudinal axis and built up from individual auger sections releasably secured together end-to-end; (b) water-jet means provided on a leading end of a leading section of the auger, which water-jet means is adapted to direct a waterjet forwardly, and parallel or generally so, to the longitudinal axis of the auger; (c) means to supply high pressure water to the water-jet means; (d) feed means to feed the auger along the bore, and subsequently to retract the auger from the bore, and (e) rotary power means to rotate the auger to convey the mineral from the bore.

10. Apparatus for carrying out the method of any one of Claims 2 to 8, additionally provided with second water jet means mounted on one section of the auger and adapted to direct water-jet(s) laterally and/or rearwardly.

11. Apparatus as claimed in Claim 10, wherein the second water jet means is mounted either on the leading auger section, or on an adjacent auger section, or on any other auger section.

12. Apparatus as claimed in Claim 10 or Claim 11, when appendant to Claim 6 or Claim 7, provided with phasing means.

13. Apparatus as claimed in Claim 12, wherein the phasing means is a cam arrangement.

14. Apparatus as claimed in any one of Claims 9 to 13, wherein each auger section comprises an inner barrel part, with an auger vane secured around the outer periphery of the barrel part.

15. Apparatus as claimed in any one of Claims 9 to 14, wherein the auger vane is provided with a rim extending around its peripheral edge.

16. Apparatus as claimed in any preceding Claim, wherein the high pressure water supply is provided by at least one water pipe or hose.

17. Apparatus as claimed in Claim 16, wherein a single pipe or hose is provided.

18. Apparatus as claimed in Claim 17, when appendant to Claim 10, wherein a changeover valve is employed to switch the supply between the first and second water jet means.

19. Apparatus as claimed in any one of Claims 9 to 18, wherein the feed means is hydraulically powered.

20. Apparatus as claimed in Claim 19, wherein the feed means incorporates an hydraulic motor and an endless chain drive.

21. Apparatus as claimed in any one of Claims 9 to 20, wherein the feed means comprises a pair of spaced-apart, parallel slide tracks mounted on a support structure.

22. Apparatus as claimed in Claim 21, wherein the support structure is provided with adjustable levelling legs.

23. Apparatus as claimed in Claim 22, wherein the legs are of a hydraulic piston and cylinder kind.

24. Apparatus as claimed in Claim 21, when appendant to Claim 20, wherein a carriage is displaceble along the slide tracks, on which carriage the rotary power means is supported, with the carriage attachable to the endless chain drive.

25. Apparatus as claimed in any one of Claims 9 to 24, wherein the rotary power means is hydraulically actuated, incorporating an hydraulic motor, with a drive connection between the motor and the trailing auger section.

26. Apparatus as claimed in Claim 25, wherein a gearbox is interposed between the motor and the trailing auger section.

27. A mineral cutting method substantially as hereinbefore described with reference to the accompanying drawings.

28. Apparatus for carrying out the method of Claims 1 to 8 and 27, substantially as hereinbefore described with reference to the accompanying drawings.