GB2285075A - Mining apparatus and method - Google Patents

Abstract

First and second sets of roof supports, a mining conveyor and a cutter associated with the mining conveyor are provided. Roof supports of the second set are intermingled with supports of the first set, and the two sets have different roof supporting canopy formations. Intermingling the two sets and controlling the advancement of roof supports of the first set separately from roof supports of the second set, enables both the cutting of material from the mine face and the stowing of packing material in an area behind the roof supports to be carried out simultaneously, and without interruption.

Description

MINING APPARATUS The invention relates to a method and apparatus for permitting both the cutting of material from a mine face and the "stowing" of material behind mine roof supports.

In particular, the present invention relates to a method and apparatus for permitting the execution of a stowing operation whilst cutting is carried out at the same time.

In conventional longwall mining techniques, subsequent to advancement of the mining conveyor, each roof support is consecutively advanced so as to leave an unsupported area of mine roof, which then falls behind the canopies of the now advanced roof supports. However, in certain conditions, for example, where mining takes place under urban areas, it is not desirable to use this technique as ground subsidence at surface level is not permissible.

For the reason given above, in such locations, it is necessary to pack, or "stow" material behind the roof supports so as to prevent, or at least limit, cave-in of the roof once the supports have advanced.

Stowing tends to be a relatively slow operation, whereas cutting of material at the coal face is relatively quick, and it is therefore, common practice to cut and stow in a three shift operation, the first two shifts comprising cutting shifts, and the third shift being used for stowing material. The two operations are carried out completely separate from one another.

It is therefore desirable to provide a means and method which permits stowing to be carried out at the same time as the normal cutting and conveyor advancement operations.

According to a first embodiment of the present invention, a method of cutting material at a mine face is provided comprising the steps of positioning a first set of roof supports and a second set of roof supports, which second set is intermingled with supports of said first set, a mining conveyor being provided in front of said roof supports, and a cutter being associated with said conveyor in an initial configuration with respect to said face; commencing cutting of a first web of material from the face; advancing the conveyor in sections towards the face; advancing the first set of roof supports towards the face, whilst maintaining said second set in their initial positions; and stowing packing material into an area behind said roof supports whilst continuing to cut material from the face.

Maintaining the second set of roof supports in position, subsequent to advancement of the first set of roof supports enables the second set to continue to support a rear section of mine roof, whilst the first set follows the advance of the conveyor and supports a front section of the mine roof. This enables the packing of stowing material to be carried out whilst the first and indeed subsequent webs are being cut from the face.

Cutting material from the face is a faster operation than stowing packing material behind the supports and typically three or four complete webs can be cut from the face during the time in which it takes to stow material behind the supports across the full length of the face.

Preferably, the first set of roof supports are each provided with a roof supporting canopy of a first type and the second set of roof supports are each provided with a roof supporting canopy of a second type.

Preferably, the first type of canopies taper towards the rear of their respective roof support, and the second type of canopies taper towards the front of their respective roof support.

As during the cutting of material from the face, roof supports of the first set are advanced towards the face subsequent to conveyor advance, whilst roof supports of the second set are maintained in position, it is important that support for the mine roof is maintained both towards the face and towards the rear. Providing the second set of roof supports with canopies of the second type and roof supports of the first set with canopies of the first type, ensures that the critical regions to the front and rear of the roof are supported.

Preferably, the roof supports of both the first and second sets are provided with front and rear extensions.

Preferably, subsequent to commencing cutting of the first web, but prior to advancement of the conveyor, the front extensions of each canopy are extended.

Preferably, the method further comprises Preferably, the method further comprises cutting a second web of material from the face; advancing the conveyor in sections towards the face; further advancing the first set of roof supports towards the face, whilst maintaining at least some roof supports of the second set in their initial positions; and continuing stowing.

Preferably, once a given amount of stowing has taken place behind a given roof support of the second set, that roof support is then advanced.

Preferably, a third web and, optionally, a fourth web of material may be cut from the face using the method of the present invention, whilst at least some of the roof supports of the second set may remain in their initial positions.

Preferably, stowing is carried out to a depth of n webs across the entire length of the coal face, whilst n cutting operations are being performed.

According to a second aspect of the invention, mine roof supports having two different types of canopies are provided, wherein the first type of canopy tapers towards a front of the roof support, and the second type of canopy tapers towards a rear of the roof support.

The invention includes a control system for sequencing movement of roof supports of first and second sets in accordance with the method of the first aspect of the present invention.

The control system may be a hydraulic control system or a electronic control system.

The invention includes tapering canopies for roof supports used in accordance with the method of the present invention.

By way of example, a specific embodiment of the present invention will now be described, with reference to the accompanying diagrammatic drawings, in which Figures la to le are schematic plan views which illustrate an embodiment of the method of the present invention; Figure 2 is a side view showing a roof support of a first type; Figure 3 is a plan view showing the canopy configuration of the roof support of Figure 2; Figure 4 is a side view showing a roof support of a second type; Figure 5 is a plan view showing the canopy configuration of the roof support of Figure 4; and Figure 6 is a side view showing a roof support of a similar type to that shown in Figure 4, but incorporating a stow support system.

Referring initially to Figure 1, an embodiment of the method of the present invention will now be described.

In Figure la, a plurality of roof supports of first and second types are shown. Roof supports 1 to 34 are of the first type, and roof supports 1' to 33' are of the second type.

In Figure la, the roof supports are shown in their initial configuration behind a conveyor 35 which is positioned parallel to a mine face 36.

As can be seen from the Figure, roof supports of the first type have a canopy which tapers towards their rear (i.e. away from the face), whilst roof supports of the second type have canopies which taper towards the front (i.e. towards the face).

In the position shown in Figure la, a cutting tool, or shearer, (not shown) which cuts material from the coal face 36 is positioned to the right of the coal face at a position 37 which is known as the main gate.

The shearer is thereafter moved from right to left along the coal face 36 so as to cut away a first web of material. The conveyor is moved towards the newly cut face in sections by pushing each section forwards from the roof supports as the shearer moves along the coal face.

For this operation, the conveyor is moved forwards in a conventional manner by rams of the roof supports.

In Figure lb, it can be seen that roof supports 1 to 8 have been advanced by the first web distance, whereas their neighbouring supports of the second type 1' to 8' have remained in their initial configuration.

In fact, Figure lb shows the mine face in a condition where approximately half of the first web of material has been cut. To get into the configuration shown in Figure lb, roof supports 1 to 8 of the first type would have been advanced one by one into their position shown, following advancement of their particular conveyor section by the first web distance.

By retaining the roof supports of the second type, in their initial configuration, the stowing of packing material to the rear of roof supports 1' to 33' may be commenced.

As will be described hereinafter, roof supports of the first and second types each have retractable extension sections, or cantilevers, to their front and rear, and to get from the condition shown in Figure la to that shown in Figure lb, the method, in more detail, comprises commences cutting of the first web from right to left as shown in the Figure, advancing the front cantilevers of each of the roof supports 1 to 34, so as to provide support to the front section of a mine roof following passage of the shearer, pushing the conveyor over in sections behind the shearer, advancing the roof supports 1 to 34 one at a time, with their front cantilevers now retracted, and then extending the rear cantilevers of those roof supports one by one.

The process illustrated in Figure 1b continues until the configuration reached in Figure lc is attained, by which point the shearer is at a position 38 known as the tail gate. In the configuration shown in this Figure, each of the roof supports 1 to 34 of the first type have been advanced by one web, and they each have their rear cantilevers out, whilst the roof supports 1' to 33t are positioned one web back from the roof supports of the first type supporting the rear section of the mine roof and allowing the stowing of packing material to continue.

For those roof supports 1' to 3' of the second type, in which stowing has been completed, those supports can now be advanced as shown.

Following position lc, the shearer is moved from the tail gate 38 to cut a second web from left to right as shown in Figure ld. Once again, some of the roof supports of the second type 33' to 18' are kept in their initial configuration so that following passage of the shearer, and advancement of the conveyor in sections, and advancement of the roof supports 34 to 31 of the first type, they are now two webs behind their neighbours.

Advancement of the roof supports of the first type, advancement of the conveyor sections, and extension and retraction of cantilever sections is carried out in similar fashion to that already described whilst cutting the first web. In the meantime, stowing is continued behind the roof supports of the second type from right to left.

It will be noted from Figure ld, that due to the advancement of the roof supports of the first type, whilst, in the extreme case, retaining roof supports of the second type in their initial configuration, gaps 39, 40 appear between the roof supports. In practice, the gaps so formed are of no concern due to the two different types of canopy which are employed, i.e. the front section of the mine roof (i.e. that section of the roof close to the face) is adequately supported across the greater part of its length by roof supports of the first type as these supports have canopies which are wider towards their are narrower towards their forward-most regions. The reverse situation holds for the rear section of the mine roof. Therefore, in the critical areas, at front and rear of the mine roof, there is, in fact, a sufficiently large supported area of roof to maintain safe working conditions.Furthermore, weight distribution from front to back across the roof supports taken as a whole is evenly spread.

After the second web of material has been cut a third web is cut as shown in Figure le. In this particular example, it is assumed that during the time it takes to cut three webs of material from the coal face a single stowing operation can be carried out across the whole length of the face from right to left. Therefore, as shown in Figure le, once stowing has been completed behind the roof supports of the second type, those roof supports can be fully advanced, so that shortly after the shearer has reached the tail gate 38 of Figure le, the configuration can be returned to that shown in Figure la and cutting and stowing started all over again.

The construction of the two different types of roof supports will now be described in more detail, referring to Figures 2 to 7.

In Figures 2 and 3, a roof support of the first type, is shown generally at 1. The support comprises a base 50, a canopy 51 having a front 52 and rear 53 extendable cantilever extensions, a number of hydraulic rams, or legs 54, 55 and a rear shield element 56. The roof support 1 is further connected to a section 57 of the mining conveyor 35 by an advancing ram (not shown for reasons of clarity).

conveyor 35 by an advancing ram (not shown for reasons of clarity).

The roof support 1 is quite conventional in operation, and this operation will not be gone into in any further detail here, the main distinctive feature however of this roof support lies in the nature of the canopy and, in particular, in the complementary forms of canopies provided on roof supports of the first and second types.

Referring now to Figures 4 and 5, a roof support of the second type is shown generally at 1'. In Figure 4, parts of the roof support 1' which are essentially identical to the parts of roof support 1 shown in Figure 2, are designated by like reference numerals. The canopy of roof support 1' has a main section 58, a rear extendable cantilever section 59 and a front extendable cantilever section 60.

Referring to Figures 3 and 5, the interaction between the different canopy shapes will now be explained.

The front cantilever 52 of the roof support 1 is extendable from a first position shown in solid lines, to a second position shown in broken lines, and this extension is carried out subsequent to passage of the shearer along the face past that particular roof support 1, prior to pushing the conveyor section 57 forwards.

After moving the conveyor section forwards, the roof support 1 is then pulled forwards in a conventional manner and rear extension 53 moved from its retracted position, shown in solid lines in Figure 3, to an extended position shown in broken lines. Moving the extendable sections in this manner, ensures that the roof is adequately supported at all times.

Similarly, roof supports of the second type, such as the support 1', are arranged to extend their front cantilever section 60 following passage of the shearer and prior to conveyor advancement. In practice, the front cantilever section 60 may be larger than shown so that even with the conveyor advanced by three webs from its initial position, and with the roof support 1' in its initial, essentially unmoved position, near total roof support coverage may be given.

However, it is, as explained previously, in fact not strictly necessary to have such a large extension as due to the fact that roof supports of the first type have a canopy which, including the extendable sections, is much larger to the front than to its rear, the small section of roof area which would be unsupported by canopies of the second type, following advancement of canopies of the first type, is sufficiently small so as to be within acceptable limits. Similarly, as the canopies of roof supports of the first type have a relatively narrow rear area 53, and canopies of the second type have a large rear area 59, any section of the rear roof area which is unsupported following advancement of conveyors of the first type is also within acceptable limits.

Referring now to Figure 6, the stowing of packing material into the area behind the roof supports will now be explained.

In Figure 6, a roof support identical to that shown in Figure 4 is shown, but, in addition, a stow support system 62 is shown.

In use, whilst the first and subsequent webs are being cut, stowing is commenced by pumping stowing material, which typically comprises a sand and water mix through stow pipe 61 and, by a system of valves, pumping the stow material into the area behind the second set of roof supports. Stowing is carried out to a predetermined depth of, for example, three times the web distance. The material is pumped behind the extendable support system 62 so as to allow the material to build up behind those supports. The stow pipe 61 is shared by each of the roof supports of the second type, and valves are provided along its length so that to begin with, stowing is carried out at the right hand end (as viewed from Figure 1) and then gradually extended through to the left hand end.

In each case, once enough stowing material has been packed into the area behind a given number of supports, valves for that particular area are closed off and other valves opened so as to permit stowing material to flow into a neighbouring region.

Once a sufficient amount of stowing material has been packed into the area behind any one of the given roof supports of the second type, that roof support is advanced, as there is no longer any need for that support to stay in position, since the stowing material will now be providing the roof support function. Therefore, that particular support is free to move forwards behind its neighbouring supports of the first type.

It will be appreciated that sequencing of roof support movements may be achieved by the use of an appropriate hydraulic, or electronic, control system, as indeed can conveyor and shearer advancement.

Alternatively, control of hydraulic valves etc may be carried out manually.

It will also be appreciated, that roof supports having canopies of differing configurations may be utilised with the present invention. However, it has been found particularly advantageous that such canopies should, for the first type of roof support, be wider at the front than the back, and for the second type of roof support, should be wider at the back than the front. For instance, an alternative canopy shape could be triangular, with the "pointed end" of the triangle being forward facing for roof supports of the second type, and rearward facing for roof supports of the first type.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (17)

CLAINS

1. A method of cutting material at a mine face, the method comprising the steps of positioning a first set of roof supports and a second set of roof supports, which second set is intermingled with supports of said first set, a mining conveyor being provided in front of said roof supports, and a cutter being associated with said conveyor in an initial configuration with respect to said face; commencing cutting of a first web of material from the face; advancing the conveyor in sections towards the face; advancing the first set of roof supports towards the face, whilst maintaining said second set in their initial positions; and stowing packing material into an area behind said roof supports whilst continuing to cut material from the face.

2. A method according to claim 1, wherein roof supports of the first set are each provided with a roof supporting canopy of a first type and roof supports of the second set are each provided with a roof supporting canopy of a second type.

3. A method according to claim 2, wherein the first type of canopies taper towards the rear of their respective roof support, and the second type of canopies taper towards the front of their respective roof support.

4. A method according to any of claims 1 to 3, wherein the roof supports of both the first and second sets are provided with front and rear extensions.

5. A method according to claim 4, wherein subsequent to commencing cutting of the first web, but prior to advancement of the conveyor, the front extensions of each canopy are extended.

6. A method according to any of the preceding claims, wherein oiice a given amount of stowing has taken place behind a given roof support of the second set, that roof support is then advanced.

7. A method according to any of the preceding claims, wherein the method further comprises cutting a second web of material from the face; advancing the conveyor in sections towards the face; further advancing the first set of roof supports towards the face, whilst maintaining at least some roof supports of the second set in their initial positions; and continuing stowing.

8. A method according to claim 7, wherein a third web of material can be cut from the face whilst at least some of the roof supports of the second set remain in their initial positions.

9. A method according to claim 8, wherein further subsequent webs of material are cut from the face, whilst at least some of the roof supports of the second set remain in their initial positions.

10. A method according to any of the preceding claims, wherein stowing is carried out to a depth of n webs across the entire length of the coal face, whilst n cutting operations are being performed.

11. A method substantially as herein described with reference to the accompanying drawings.

12. Mining apparatus for use in accordance with the method of any of claims 1 to 10, the apparatus comprising mine roof supports having first and second different types of canopies, wherein the first type of canopy tapers towards a front of the roof support, and the second type of canopy tapers towards a rear of the roof support.

13. A control system for sequencing movement of roof supports of first and second sets in accordance with the method of any of claims 1 to 10.

14. A control system according to claim 12, wherein the control system is a hydraulic control system.

15. A control system according to claim 12, wherein the control system is an electronic control system.

16. A tapering canopy for a roof support of the first type as claimed in claim 11.

17. A tapering canopy for a roof support of the second type as claimed in claim 11.