GB2238337A

GB2238337A - Mineral cutting drum

Info

Publication number: GB2238337A
Application number: GB9025498A
Authority: GB
Inventors: George Albert Parrott
Original assignee: Minnovation Ltd
Current assignee: Minnovation Ltd
Priority date: 1989-11-23
Filing date: 1990-11-23
Publication date: 1991-05-29
Also published as: GB9025498D0; GB8926518D0

Abstract

In a mineral cutter drum (4) incorporating a plurality of extraction tubes (10), a water spray nozzle (11) associated with each extraction tube (10), a water supply path (14, 13) extending radially outwardly to each nozzle (11) from a central zone at an inner end of the drum (4), and a water conduit (23) extending generally axially of the drum (4) and adapted, in use, to convey water from an outside source into the drum (4), an attachment comprises a monitoring probe (15) adapted to be permanently associated with each extraction tube (10), an air supply path (17, 16) extending radially outwardly to each probe from the central zone at the inner end of the drum, and a air supply conduit (20, 22) also extending generally axially of the drum and adapted, in use, firstly to convey air into the drum for discharge at a discharge aperture of each probe under the suction effect generated by operation of the water spray nozzles, and secondly to provide for measurement, outside the drum of the vacuum levels within the extraction tubes. <IMAGE>

Description

MINERAL CUTTING DRUM ETC.

This invention relates to an attachment for a mineral cutting drum which is adapted to be mounted on a so-called shearer type mining machine for reciprocation along a coal face; to a drum provided with such an attachment; and to a mining machine provided with such a drum.

As coal mining results in the release of methane from the coal seam and/or loosened coal during mining operations, standard practice is to ventilate the drum area with "fresh" air, with a view to diluting the methane level in the atmosphere around the drum to one below an i g ni table mix, or at least to confine any ignition to the zone of the drum.

In the past, ventilation has been of the so-called hollow shaft kind (known as "hollow shaft ventilation" or H.S.V.), with fresh air driven by a water spray down a hollow shaft co-axial with the drum axis, conveying "afresh" air from the goaf side of the drum to exit, disperse, and dilute methane at the face side of the drum.

In more recent times, H.S.V. has been superseded at least in the British coal industry with a so-called extraction drum, in which the air flow (being air or an air/methane mixture) is in the opposite direction to H.S.V., with air drawn along a plurality of e.g. nine, tubes arranged circumferentially within the drum, at spaced apart, angular locations, with the tube axes parallel to the drum axis. Air flow is again induced by water jets.

Under mining conditions however, some or all of the tubes or jets may become blocked with debris, and flow and pressure monitoring of the water cannot be guaranteed to indicate the true ventilating conditions of a drum. Of course, mining regulations demand air flow monitoring measurements at regular periods, but this can only be done with the machine in a non-cutting mode and hence does not truly represent working conditions.

The object of the present invention is to provide a mineral cutting drum etc of the extraction type, in which ventilation effectiveness can be monitored during cutting operations, According to a first aspect of the present invention there is provided an attachment for a mineral cutter drum of the so-called extraction type incorporating a plurality of extraction tubes, a water spray nozzle associated with each extraction tube, a water supply path extending radially outwardly to each nozzle from a central zone at an inner end of the drum, and a water conduit extending axially, or generally axially, of the drum and adapted, in use, to convey water from an outside source into the drum, the attachment comprising a monitoring probe adapted to be permanently associated with each extraction tube, an air supply path extending radially outwardly to each probe from the central zone at the inner end of the drum, and a air supply conduit also extending axially, or generally axially, of the drum and adapted, in use, firstly to convey air into the drum for discharge at a discharge aperture of each probe under the suction effect generated by operation of the water spray nozzles, and secondly to provide for measurement, outside the drum, of the vacuum levels within the extraction tubes.

According to a second aspect of the present invention there is provided a mineral cutting drum of the so-called extraction type, provided with an attachment in accordance with the first aspect.

Thus, the first aspect of the invention provides an attachment for retro-fitting to existing extraction drums, and as drums frequently incorporate a speed reduction gearbox, the water and air conduits readily pass through the centre of the gearbox. In use, as the pressure sensed at the manometer type device on the machine body is below the atmospheric pressure existing in a mine, a vacuum level is in fact being sensed and/or monitored, with a threshold vacuum, known from experimentation and/or test, below which threshold unsatisfactory ventilation and hence blockage of a jet nozzle(s) or an extraction tube(s) can be predicted.In principle therefore the invention thus provides the possibility of dynamic sensing of the level of vacuum and thus predictable flow volumes of air through the drum during cutting operations and hence under real conditions, such measurement indicating not only that the associated water jets are discharging satisfactorily and hence are not blocked, but also that the associated extraction tubes into which the jets are directed is likewise not blocked and hence a satisfactory air flow through the extraction tubes is occuring. Quite simply if the vacuum level lowers from a prescribed value, at least one water jet and/or its extraction tube is blocked.

Although individual water and air conduits, e.g. of metal tubing, could be provided, preferably both are incorporated into a duplex conduit, to provide an integral, one-piece unit providing for both vacuum/air pressure feed from the drum and water feed to the drum, that may be readily fitted to a drum of conventional design. The duplex, concentric conduit is such that an inner core not only carries vacuum out of the drum, but also carries air into the drum, and specifically to the batch of probes in volumes dictated by the rate of air discharge or bleed from the probes, which is in turn dictated by the vacuum levels within the individual extraction tubes, while the outer annulus carries water into the drum, for eventual discharge at the water spray nozzles.

A triplex conduit or quadruplex may in fact be used if additional water, possibly at a different pressure, is required for other uses, such as pre-start warning, pick face flushing etc. The duplex etc., conduit, need not be co radial, but could for instance be semi-circular (or "D" Section) or quarter-circular.

It is preferred for the sensing means to take the form of a Pitot-like tube so that the one conduit portion is constituted by a vacuum line, Preferably, each water spray nozzle generates a conical water spray into the extraction tube, so as to induce air flow along the extraction tube, while a terminal end of the Pitot tube extends into the extraction tube but is outside the spray cone.

Although the radial hoses could be of synthetic plastics material, preferably at least the air supply path, and conveniently the water supply path, is provided by a manifold at the inner end of the drum, which manifold may be generally annular, with the air supply paths formed by radially extending bores drilled into the manifold, the latter conveniently being formed by burning from plate metal, e.g. to form three or four spoked arms into which the radial bores are drilled. For the manifold also to serve for water supply, additional radial bores may simply be drilled, e.g. into the radial arms, to constitute the radial, water supply paths, to the individual spray nozzles.

The axial conduit(s) whether single, duplex, triplex or quadruplex, may be synthetic plastics or metallic and is/are conveniently located in, and extend(s) along, a hollow metal shaft co-axial with the drum axis.

According to a third aspect of the present invention, there is provided a shearer type mining machine provided with at least one drum in accordance with the second aspect, with an end of the gas conduit, at the outer end of the drum, connected to a manometer type device located on or in a body portion of the machine to provide a vacuum reading or display.

Apart from the vacuum level being displayed in a form readable by the machine operator, it may also be fed into the conventionally provided MIDAS system, for remote display.

The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an axial sectional view through an attachment and drum in accordance with the first and second aspects respectively of the invention; Figure 2 is a view to an enlarged scale of area A of Figure 1; Figure 3 is a view in the direction of arrow B of Figure 2; and Figure 4 details a water and air distribution manifold.

In the drawings, a ranging arm 1 is pivotally attached to one end of a so-called shearer type mining machine (not shown) for pivotal movement, in the conventional manner, under the control of a double-acting advancing ram, about an axis directed towards the face of a coal etc., seam, with the machine being advanced along the seam, and the arm being displaced in accordance with cutting requirements, seam undulations etc.

Also conventionally, the arm 1 provides a gear box 2 incorporating power transmission gears 3 to transmit torque from a motor, usually an electric motor, within the body of the machine, to a rotary cutting drum 4, Although not illustrated, the latter is again provided with a plurality of pick boxes each to receive a mineral cutter pick, and incorporates a mounting collar 5 by which the drum 4 is attached by bolts 6 to an end ring 7 mounted via splines 8 on a drive shaft 9 driven by the gearing 3.

The drum 4 is, conventionally, provided with a plurality of extraction tubes 10 and, as best seen in Figure 2, a water spray nozzle 11 is associated with each extraction tube 10 to generate a conical spray 12 which induces an air flow along the extraction tube creating a vacuum at zone 24. The nozzle 11 is supplied with water from a water supply path 13 attached to a supply port 14 located at a central zone distribution point at the inner end of the drum. Also associated with each extraction tube 10 is a Pitot tube 15 connected by an air supply path 16 to a port 17 also located at the central zone at the inner end of the drum.

Co-axial with the axis of rotation of the drum 4 and shaft 9 is a metallic, duplex conduit 18 extending along a hollow interior 19 of the drive shaft 9, an inner core 20 of the conduit 18 being connected to the port 17, air supply path 16 and Pitot tube 15, and hence serving to carry vacuum from the drum 4, and specif.ically from the individual extraction tubes 10, while an outer annulus 21 of the conduit 18 serves to carry water into the drum, and specifically to the port 14, water supply path 13 and nozzle 11. From the ports 14 and 17 at the inner end of the central zone of the drum 14, water and air are distributed radially to the nozzles 11 and tubes 15 respectively, by water and air supply paths, and specifically by radial bores 25 drilled into a manifold plate 26. At its other end, the conduit 18, and specifically its inner core 20 and outer annulus 21, are connected to ports 22 and 23 for gas extraction and water supply respectively.

Control means may be readily provided to issue an audible and/or visual warning and/or to effect machine shut down, should the vacuum level reach a predetermined threshold indicating malfunctioning of the ventilating system.

Claims

1. An attachment for a mineral cutter drum of the so-called extraction type incorporating a plurality of extraction tubes, a water spray nozzle associated with each extraction tube, a water supply path extending radially outwardly to each nozzle from a central zone at an inner end of the drum, and a water conduit extending axially, or generally axially, of the drum and adapted, in use, to convey water from an outside source into the drum, the attachment comprising a monitoring probe adapted to be permanently associated with each extraction tube, an air supply path extending radially outwardly to each probe from the central zone at the inner end of the drum, and a air supply conduit also extending axially, or generally axially, of the drum and adapted, in use, firstly to convey air into the drum for discharge at a discharge aperture of each probe under the suction effect generated by operation of the water spray nozzles, and secondly to provide for measurement, outside the drum, of the vacuum levels within the extraction tubes.

2. An attachment as claimed in Claim 1, wherein individual water and gas conduits are provided.

3. An attachment as claimed in Claim 1, wherein a duplex conduit is provided for water and gas.

4. An attachment as claimed in Claim 3, wherein the conduit comprises an inner core to carry vacuum out of the drum, while the outer annulus carries water into the drum.

5. An attachment as claimed in Claim 1, wherein a triplex conduit is provided.

6. An attachment as claimed in Claim 1, wherein a quadruplex conduit is provided.

7. An attachment as claimed in Claim 3, 5 or 6, wherein the conduit has a cross section other than concentric.

8. An attachment as claimed in any preceding Claim, wherein the probes takes the form of a Pitot-like tube.

9. An attachment as claimed in any preceding Claim, wherein each water spray nozzle generates a conical water spray into the extraction tube, so as to induce air flow along the extraction tube, while a terminal end of the Pitot tube extends into the extraction tube but is outside the spray cone.

10. An attachment as claimed in any preceding Claim, wherein the air supply path is provided by a manifold at the inner end of the drum.

11. An attachment as claimed in Claim 10, wherein the manifold is generally annular, with the air supply paths being formed by radially extending bores drilled into the manifold.

12. An attachment as claimed in Claim 10 or Claim 11, wherein the manifold is burnt to shape from plate metal.

13. An attachment as claimed in any one of Claims 10 to 12, wherein the manifold comprises three or- four spoked arms into which the radial bores are drilled.

14. An attachment as claimed in any one of Claims 10 to 14, wherein the manifold is provided with additional radial bores to constitute the radial water supply paths to the individual spray nozzles.

15. An attachment as claimed in any preceding Claim, wherein the axial conduit(s) whether single, duplex, triplex or quadruplex are synthetic plastics or metallic.

16. An attachment as claimed in any preceding Claim, wherein the axial conduit(s) whether single, duplex, triplex or quadruplex is/are conveniently located in, and extend(s) along, a hollow metal shaft co-axial with the drum axis.

17. An attachment for a mineral cutter drum, substantially as hereinbefore described with reference to the accompanying drawings.

18. A mineral cutting drum of the so-called extrtaction type, provided with an attachment as defined in any preceding Claim.

19. A mineral cutting drum substantially as hereinbefore described with reference to the accompanying drawings.

20. A shearer type mining machine provided with at least one drum as defined in Claim 18 or Claim 19, with an end of the gas conduit, at the outer end of the drum connected to a manometer type device located on or in a body portion of the machine to provide a vacuum reading or display.

21. A shearer type mining machine substantially as hereinbefore described with reference to the accompanying drawings.