GB2190939A

GB2190939A - Mineral cutting machine

Info

Publication number: GB2190939A
Application number: GB08612766A
Authority: GB
Inventors: Harry James Fruin; Patrick Britton
Original assignee: Dresser UK Ltd
Current assignee: WLTD Ltd
Priority date: 1986-05-27
Filing date: 1986-05-27
Publication date: 1987-12-02
Also published as: GB8612766D0

Abstract

A method of steering a mineral cutting machine 1 and/or cutting element thereof along a mineral seam or strata band 3 being mined, comprising locating a transducer 14 sensitive to a chemical composition of the mineral of the seam or band 3 in proximity to the seam or band 3, obtaining output signals from the transducer, and employing the output signals to control positional variations of the cutting element(s) 12 and/or the machine 1, as the machine 1 progresses along the seam or band 3. The invention also includes a mineral cutting machine 1 comprising at least one mineral cutting element 12, a transducer 14 sensitive to a chemical composition of the mineral of the seam or band 3, displacement means to effect positional adjustment of the cutting element 12 and/or machine 1 and a control system 15 to control the displacement means, with output signals from the transducer 14 fed to the control system 15 whereby automatically positional adjustment(s) of the cutting element 12 and/or machine 1 is effected by the displacement means. <IMAGE>

Description

SPECIFICATION Mineral cutting machine This invention relates to a mineral cutting machine and in particular to a method of automatically steering the machine and/or a cutting element(s) thereof, such that the cutting element remains located in an optimum desired position, e.g. within a mineral seam/strata band or within a particular part of a mineral seam/strata band.

It will be appreciated that an automatic steering facility ensures that the cutting element(s) remains constantly within the seam/ band and hence does not wander into rock, dirt etc. or remains within a particular part of the seam/band, so as to avoid an unwanted impurity, while furthermore, obviating the requirment for manual adjustments by the machine operator based on visual observations of the position of the cutting element(s) within the seam, particularly when visual observation is rendered difficult not only by the cloud of air-born dust in the vicinity of the cutting element but also by obstructions from ancillary equipment, e.g. chock legs of associated roof supports, spill plates of an associated conveyor etc.With regard to the unwanted impurities, it will be appreciated that in the mining of coal the principal unwanted impurity within a coal seam is sulphur, which is acceptable < 1%, but which at relatively high concentration 2%3% renders difficult if not impossible sufficiently low sulphurous emissions from the principal users of coal-power stations-to minimise the problem of acid rain.

Hence, a low sulphur content coal simplifies control of power station combustion conditions, flue gas treatments to give a minimum sulphurous emission, and whilst a machine operator can usually detect by sight and/or sound entry of the cutting element into a "hard" rock roof or floor and can manually return the cutting element into a "soft" coal seam, it is impossible for the operator to know when the cutting element is entering or leaving an area/band of high impurity e.g., sulphur or silica content, and hence impossible for the operator to control this aspect of the product quality.

Certainly in the mining of coal, there already exist known proposals for effecting automatic positional adjustment of cutting elements, (the latter usually being constituted by pick-armed, rotary cutting heads) but these methods are aimed primarily, at avoiding cutting into a (rock) roof and (rock) floor above and below a seam. Among the methods used are firstly ones which make use of the natural radiation properties of the surrounding strata and the attenuation properties of the mineral being cut, and secondly ones which rely on the properties of the mineral and the surrounding strata when being bombarded by a low level radiation source.A disadvantage of the first methods is that not all surrounding strata has sufficiently strong natural radiation properties to be useful, while with the second method, the radiation source is potentially hazardous to attendant personnel whilst with no method is it possible to avoid seam areas having unacceptably high sulphur concentration.

It is also known from U.S. 4,079,997 to employ a photoelectric technique to track the different colour of a bed of clay in a bed of potassium deposits being mined, and to steer an associated mining machine in accordance with such tracking but this photoelectric technique is not employable in coal seams for instance, where sulphur concentrations e.g., of pyrites are random and scattered, rather than being layered and hence trackable.

The object of the present invention is to provide an alternative and improved mineral cutting machine steering method and machine to previous proposals, and particularly one in which, if coal mining is involved, would provide the possibility of steering control to avoid the cutting of high sulphur content coal.

According to a first aspect of the present invention, there is provided a method of steering a mineral cutting machine and/or cutting element thereof along a mineral seam or strata band being mined, comprising locating a transducer sensitive to a chemical composition of the mineral of the seam or band in proximity to the seam or band, obtaining output signals from the transducer, and employing the output signals to control positional variations of the cutting element(s) and/or the machine, as the machine progresses along the seam or band.

According to a second aspect of the present invention, there is provided a mineral cutting machine comprising at least one mineral cutting element, a transducer sensitiVe to a chemical composition of the mineral of the seam or band, displacement means to effect positional adjustment of the cutting element and/or machine and a control system to control the displacement means, with output signals from the transducer fed to the control system whereby automatically positional adjustment(s) of the cutting element and/or machine is effected by the displacement means.

In the case of a coal seam, the transducer would be sensitive to the chemical composition of sulphur/sulphur containing compounds, so that machine steering adjustments, in accordance with signals receiVed from the transducer, can ensure that the cutting of coal with a high sulphur content e.g. above 1% can be avoided. Thus, if it should be that a band of mineral with an unacceptably high impurity content is encountered at the top or bottom of a mineral seam, then the mining of this band can be avoided and hence the contamination of the mined product with the impurity can be avoided.Alternatively, if a high impurity band e.g. 1m thick, is encountered in the middle of a 3m thick seam, then the high impurity band can be removed in the same manner as the use of a dirt band shearer in coal mining, with the impurity band disposed of e.g. in the goaf, whilst the machine may have a primary cutting element for coal etc cutting, and a secondary cutter for sulphur etc., impurity cutting. Of course, there may be some geological conditions encountered within the middle of the seam, but within so narrow a band thickness, that a dirt band pass is economically unacceptable, and hence impurity contamination is unavoidable.

It will obviously be necessary initially to set up the machine, and in particular the transducer, at one end of a seam or band, in preparation for a cutting run.

The mineral cutting element(s) may be a pick-armed, rotary cutting head; a spiral vane pick-armed rotary cutting head; a rotary trepanner head; a chain arm if a chain cutter is involved; or a water nozzle arm if water jet, or water jet assisted, cutting is involved.

The mineral cutting machine may be of the so-called shearer type thus having at least one ranging arm carrying at least one cutting element(s) rotatable about an axis extending transversely to the direction of machine advance. If of the shearer type, positional adjustment would normally be effected on a ranging arm pivotally mounted on a machine body and on which arm is mounted a rotary cutting head, although positional adjustment of the machine body is possible with shearer type machines particularly if the machine is floor mounted; and unavoidable with trepanner type machines. If of the trepanner type, the machine has a cutting element in the form of a trepanner head carried by a machine body for rotation about an axis extending in the direction of machine advance.

With any type of machine, positional adjustment is conveniently effected by one or more hydraulic rams, preferably of the double-acting kind.

It will be appreciated that the control system requires, for successful automatic steering, a number of input signals from various sources, including the transducer, the system incorporating a complex algorithm/computer program, so that the various signals are correctly married together and the machine response governed accordingly.

The invention will now be described in greater detail, by way of example, with reference to the accompanying drawing which is a diagrammatic side elevation of a double ended ranging drum shearer.

In the drawing, a shearer 1 is mounted on and guided by an armoured, scraper chain conveyor 2 extending along a mineral face 3 of a seam of mineral e.g., coal, defined between a mine floor 4, on which the conveyor 2 is seated, and a mine roof 5. The seam has a thickness T of e.g. 2m, and under conventional mining techniques, the whole thickness (or substantially the whole thickness) would be mined by the shearer 1.

The shearer 1 has a body portion 6 made up of a plurality of modules housing various required components e.g., electric motor(s), in a known manner. Thus, the body portion 6 terminates at each end in a gear head 7 having a machine haulage output sprocket 8 in driving engagement with a drive sprocket 9 engaging a rack or chain 10 extending along the conveyor 2. To each gearhead 7 is pivotally attached a ranging arm 11 under the control of a hydraulic ram (not shown) in known manner, the arm 11 in turn carrying a pickarmed rotary cutting head 12 rotatable about an axis 13 extending transversely to the direction of machine haulage to remove a web from the face 3. The body portion 6 also houses a sensing device 14 to sense, and if necessary be tuned to sense a chemical characteristic of the seam of mineral being mined.

In the example illustrated, let it be assumed that the seam is of coal, and that the sensing device 14, in scanning the thickness T of the seam detects at the upper part of the seam, a zone, of varying thickness from a minimum T1 to a maximum T2, having an unacceptably high sulphur content e.g. 23%. From the viewpoint of good mining practice, an even rather than undulating roof is much to be preferred and hence normally a depth T1 only would be unmined, with the minimal quantity of high impurity product below thickness T1 being accepted.

The body portion 6 also houses a control device 15 to receive output signals from the sensing device 14 and as a consequence of the nature of such signals to control, and/or effect through standard control engineering electro-hydraulic circuitry positional variations of the ranging arm 11 of the leading, upper cutting head 12, to avoid mining the high impurity zone and hence avoid contamination of the remaining, mined thickness of the seam with the unwanted impurity, and furthermore, if necessary, to effect positional variations of the lower, trailing ranging arm(s) 11, to maintain the trailing cutting head 12 within the mineral seam rather than penetrating the rock or dirt floor 4 which, whilst not being such an unacceptable impurity as sulphur would result in a disadvantageously uneven floor.

Instead of being located on or in the body portion 6, individual sensing devices may be mounted in or on each ranging arm 11.

Claims

1. A method of steering a mineral cutting machine and/or cutting element thereof along a mineral seam or strata band being mined, comprising locating a transducer sensitive to a chemical composition of the mineral of the seam or band in proximity to the seam or band, obtaining output signals from the trans ducer, and employing the output signals to control positional variations of the cutting element(s) and/or the machine, as the machine progresses along the seam or band.

2. A method as claimed in Claim 1, wherein the mineral seam or strata band is a coal seam and the transducer is sensitive to the chemical composition of sulphur/sulphur containing compounds.

3. A mineral cutting machine comprising at least one mineral cutting element, a transducer sensitive to a chemical composition of the mineral of the seam or band, displacement means to effect positional adjustment of the cutting element and/or machine and a control system to control the displacement means, with output signals from the transducer fed to the control system whereby automatically positional adjustment(s) of the cutting element and/or machine is effected by the displacement means.

4. A machine as claimed in Claim 3, wherein the transducer is sensitive to the chemical composition of sulphur/sulphur containing compounds.

5. A machine as claimed in Claim 4, having a primary cutting element for coal etc. cutting, and a secondary cutter for sulphur etc., impurity cutting.

6. A machine as claimed in Claim 4 or Claim 5, wherein the mineral cutting element(s) is a pick-armed, rotary cutting head.

7. A machine as claimed in Claim 4 or Claim 5, wherein the mineral cutting element(s) is a spiral vane, pick-armed rotary cutting head.

8. A machine as claimed in Claim 4 or Claim 5, wherein the mineral cutting element(s) is a rotary trepanner head.

9. A machine as claimed in Claim 4 or Claim 5, wherein the mineral cutting element(s) is a chain arm if a chain cutter is involved.

10. A machine as claimed in Claim 4 or Claim 5, wherein the mineral cutting element(s) is a water nozzle arm if water jet, or water jet assisted, cutting is involved.

11. A machine as claimed in any one of Claims 4 to 10, of the so-called shearer type having at least one ranging arm carrying at least one cutting element(s) rotatable about an axis extending transversely to the direction of machine advance.

12. A machine as claimed in Claim 11, wherein positional adjustment is effected on a ranging arm pivotally mounted on a machine body and on which arm is mounted a rotary cutting head.

13. A machine as claimed in any one of Claims 1 to 10, wherein positional adjustment is effected to the machine body.

14. A machine as claimed in any one of Claims 4 to 13, wherein positional adjustment is effected by one or more hydraulic rams.

15. A machine as claimed in Claim 14, wherein the rams are of the double-acting kind.

16. A method of steering a mineral cutting machine and/or cutting element thereof along a mineral seam or strata band, being mined, substantially as hereinbefore described with reference to the accompanying drawings.

17. A mineral cutting machine substantially as hereinbefore described with reference to the accompanying drawings.