GB2042023A

GB2042023A - Method of and apparatus for surveying a mining installation

Info

Publication number: GB2042023A
Application number: GB7905075A
Authority: GB
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1979-02-13
Filing date: 1979-02-13
Publication date: 1980-09-17

Abstract

A number of mine roof supports (1) along a coal face are provided with radiation sensors (16) for sensing radiation deriving from rock strata above the coal seam. From attenuation of the radiation the thickness of roof coal (4) left by a mining machine can be determined. <IMAGE>

Description

SPECIFICATION Method of and apparatus for surveying a mining installation This invention relates to a method of and apparatus for surveying a mining installation.

In a mining installation, it is useful ta be able to ascertain thickness of roof coal for purposes such as, for example, determining how much coal is lost by remaining at the roof after mining and for steering the mining machine.

It is known to determine roof coal thickness using either a radiation source and detector attached to a mining machine as described, for example, in our accepted British Patent Specification Serial No. 1 510386 or to use a natural radiation sensor attached to the mining machine as described, for example, in our accepted British Patent Specification Serial No. 1 525028.

An object of the present invention is to provide a method of and apparatus for surveying roof coal thickness.

According to one aspect of the present invention, a method of surveying a mining installation employing a plurality of mine roof supports arranged along a coal face of a mineral seam, the supports being advanceable towards the coal face after passage of a mining machine which traverses to and fro winning coal from the seam on each traverse comprises determining natural radiation transmitted through a residual layer of roof coal above the mine roof supports and left by the mining machine with natural radiation sensors attached to at least some of the mine roof supports to ascertain the thickness of said residual layer.

Preferably, the natural radiation sensors are arranged periodically along the line of miner roof supports along the coal face.

According to another aspect of the present invention apparatus for surveying a mining installation employing a plurality of mine roof supports arranged along a coal face of a mineral seam, the supports being advanceable towards the coal face after passage of a mining machine which traverses to and fro winning coal from the seam on each traverse comprises a plurality of natural radiation sensors attachable to the mine supports such that one or more of the mine roof supports has a respective natural radiation sensor attached thereto, each natural radiation sensor deriving a signal indicative of radiation sensed through a residual layer of roof coal left above the mine roof supports by the mining machine and signal processor means for receiving the derived signals to determine the thickness of said residual layer.

Preferably, the natural radiation sensors are arranged periodically along the coal face.

An embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure 1 is an incomplete view of a mining installation working towards a coal face worked out coal seam, Figure 2 is a partly shown side view of the installation of Fig. 1, and Figure 3 is a block electrical circuit diagram for apparatus used in the installation of Figs.

1 and 2.

Referring to Figs. 1 and 2, the mining installation includes a plurality of mine roof supports 1 arranged along a coal face 2 (see Fig. 2), only three of the roof supports being shown for convenience in Fig. 1 and one in Fig. 2. The mine roof supports 1 are disposed within a mineral seam having the coal face 2 and residual roof and floor layers of the seam are indicated at 4 and 5, respectively. The seam is situated between upper and lower rock strata 7 and 8, respectively. Coal is won from the coal seam by a mining machine which traverses to and fro along the coal face winning coal on each traverse. The machine (which is not shown) runs along an armoured flexible conveyor (also not shown). The rock strata 7 and 8 emit natural radiation source of which passes through the residual layer of coal towards the floor and roof, respectively.

Each roof support 1 comprises a base 10 and an overhead canopy 11 which is supported by the base via hydraulic legs 1 2. A forwardly extending roof beam 14 is mounted towards the front of the canopy and this can be used to support roof slightly ahead of the canopy. In order to advance a mine roof support, the canopy is first lowered from the roof by operating the legs 1 2 and then pulled towards the conveyor by double acting rams (not shown). The canopy is then raised so that the roof support is operable in its advanced position. (The armoured face conveyor is advanced by operating the double acting rams in the other direction with the roof supports anchored in position).

Approximately every fifth roof support along the coal face is provided with a natural radiation sensor 1 6. The radiation sensor is appropriately shielded so that it detects radiation reaching it through the residual layer of roof coal directly above it. Each radiation sensor can thus detect the thickness of the roof coal above it since intensity of the radiation impinging on the sensor is to some extent (dependent upon the coal homogeneity and constant initial intensity of radiation) inversely proportional to the thickness of the coal which attenuates the natural radiation.

Approximately each fifth roof support is also provided with a radar (in the microwave region of the electromagnetic spectrum) transducer 1 8 which detects the distance of the coal face (and thus the support) from the transducer by transmitting an electromagnetic signal to the coal face which is reflected thereat back to the transducer. The radar transducer is described in more detail in our copending British Patent Application Serial No.

The radar transducers have robust radomes transparent to electromagnetic radiation, the radomes protecting them from impact damage in the harsh mine environment.

Referring now to Fig. 3, the natural radiation sensors are again indicated by 1 6 and radar transducers by 1 8. Since only four of the sensors 1 6 and four of the sensors 1 8 are shown, the missing sensors and transducers are indicated by a dotted line. The output from the sensor 1 6 are connected to a signal processor 20 via an interrogator 21 and the outputs from the transducers 18, to the processor 20 via an interrogator 22.

The data processor has outputs connected to a display unit 25 for roof coal thickness and display unit 27 for coal face distance.

These outputs are also connected to a computer 30.

In operation, each natural radiation sensor senses the thickness of the residual layer 4 above it and thus above the respective roof support by deriving a signal indicative of the amount of radiation reaching it. The signals are fed to the signal processor 20 which processes the signals to deduce the thickness of the residual layer of coal along the coal face. The thickness along the coal face can be displayed graphically or minerally on display unit 25. The sensors can be interrogated serially or in any order by the interrogator 21 or any appropriate number can be interrogated at once, provided that there are sufficient cores to carry the information. In this way measurement of roof coal above the supports can be kept continuously up to date.

The data can also be fed to the computer 30 which monitors roof coal thickness and can take corrective control action if the roof coal goes outside preselected limits. The monitored value of roof coal thickness is of course one or two shears or traverses behind the machine but the computer can be programmed to allow for this.

Each radar transducer senses the distance of the coal face from the roof support. The distance of the coal face from the line of roof supports can be displayed graphically or numerically on the display unit 27. The sensors can be interrogated serially or in any order by the interrogater 22 or any number can be interrogated at once, provided that there are sufficient cores to carry the information. In this way, measurement of face distance from the supports can be kept continuously up to date. The face distance data can be fed to the computer 30 which monitors face distance.

The face distance data can be used for purposes including measurement of extraction rate, or determining the cutting web of the mining machine as a parameter in steering of the roof supports. Thus, since face distance is known both before and after the machine passes a radar transducer, the cutting web can be determined and since the distance travelled and speed of the machine are known, the rate of extraction can be determined. This is conveniently done by the computer 30 which continually takes the product of cutting web and machine travel (which latter is for example as described in our accepted UK Patent Specification Serial No.

1525027).

From the above description, it can be seen that an improved method of and apparatus for surveying roof coal thickness is provided.

Claims

1. A method of surveying a mining installation employing a plurality of mine roof supports arranged along a coal face of a minersl seam, the supports being advanceable towards the coal face after passage of a mining machine which traverses to and fro winning coal from the seam on each traverse comprises determining natural radiation transmitted through a residual layer of roof coal above the mine roof supports and left by the mining machine with natural radiation sensors attached to at least some of the mine roof supports to ascertain the thickness of said residual layer.

2. A method as claimed in claim 1, wherein the natural radiation sensors are arranged periodically along the line of mine roof supports along the coal face.

3. Apparatus for surveying a mining installation employing a plurality of mine roof supports arranged along a coal face of a mineral seam, the supports being advanceable towards the coal face after passage of a mining machine which traverses to and fro winning coal from the seam on each traverse comprises a plurality of natural radiation sensors attachable to the mine supports such that one or more of the mine roof Supports has a respective natural radiation sensor attached thereto, each natural radiation sensor deriving a signal indicative of radiation sensed through a residual layer of roof coal left above the mine roof supports by the mining machine and signal processor means for receiving the derived signals to determine the thickness of said residual layer.

4. A method of surveying a mining installation substantially as hereinbefore described with reference to the accompanying drawings.

5. Apparatus for surveying a mining installation substantially as hereinbefore described and as shown in the accompanying drawings.