WO2000008305A1

WO2000008305A1 - Mine support and ventilation system

Info

Publication number: WO2000008305A1
Application number: PCT/GB1998/002304
Authority: WO
Inventors: William Conly Annandale
Original assignee: Jackson, Peter, Arthur
Priority date: 1998-07-31
Filing date: 1998-07-31
Publication date: 2000-02-17
Also published as: AU8552798A

Abstract

The invention concerns a method of providing support and controlled ventilation in a mine working (10). In the method, inflatable bags (28, 30) are positioned adjacent one another in the mine working and are inflated so as to form mine supports extending between the floor and the roof of the mine working. The bags (28, 30) are positioned in relation to one another so as to form, in combination, ventilation barriers which separate previously mined zones (36) of the mine working from active zones (14, 24) in which mining activities are being conducted. Ventilating air is delivered preferentially to the active zones.

Description

MINE SUPPORT AND VENTILATION SYSTEM

BACKGROUND TO THE INVENTION

THIS invention relates to a mine support and ventilation system and in particular to a method of providing support and controlled ventilation in a mine working.

Two important aspects of underground mining practice, particularly in deep gold mines, are provision of adequate hanging wall or roof support and provision of adequate ventilation to ensure a comfortable and safe working environment. As far as the provision of roof support in mine stopes is concerned, one conventional practice is to install individual mine supports, typically in the form of packs and props, at spaced apart positions in the stope. Traditionally the entire stope, including sections which have already been mined out, is fully ventilated with cooled air. SUMMARY OF THE INVENTION

According to the present invention there is provided a method of providing support and controlled ventilation in a mine working, the method comprising the steps of positioning inflatable bags adjacent one another in the mine working and inflating the bags to form mine supports extending between the footwall or floor of the mine working and the hanging wall or roof thereof, the bags being positioned in relation to one another so as to form, in combination and when inflated, ventilation barriers which separate previously mined zones of the mine working from active zones in which mining activities are being conducted, and delivering ventilating air at least primarily to the active zones.

Where the mine working has a mining face and includes a series of panels along the mining face with gullies transverse to the mining face between adjacent panels, the method typically comprises the steps, in each panel, of positioning the bags to form a ventilation barrier extending alongside the gullies and across the mining face thereby to separate an active zone of the panel, which includes the gullies and the vicinity of the mining face, from the remainder of the panel, and of delivering ventilating air at least primarily to the said active zone. Blast curtains may be suspended from the bags at least where the ventilation barrier extends across the mining face, thereby to protect the bags from blasting carried out at the mining face. In a preferred further step of the method, carried out after blasting and clearing operations have been carried out at the mining face and the mining face has advanced accordingly, those bags where the ventilation barrier extends across the mining face are deflated and advanced in the mining direction to keep pace with the advance of the mining face. The invention also provides, for use in the above method, an inflatable bag comprising a hollow, elongate, flexible tube having a transverse dimension selected, when the tube is inflated, which is sufficient to extend between the hanging wall or roof and the footwall or floor of the mine working, clamps which clamp the ends of the tube closed to form an enclosure, and an inflation inlet into the enclosure controlled by a non-return valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a diagrammatic plan view of a stope in a gold mine in which the system of the invention is implemented; and

Figure 2 shows a perspective view of an inflatable bag.

SPECIFIC DESCRIPTION

Figure 1 shows a typical underground gold mine working in which three adjacent panels of the mine working are designated with the numeral 10. The mining face in each panel is designated by the numeral 12, and transverse gullies 14 separate the panels from one another. In conventional mining practice, as indicated in the left and right side panels, mine supports, typically in the form of timber-based packs 20, are installed at spaced apart positions along the length of the gullies to provide support for the hanging wall alongside the gullies. Rows of elongate mine props 22 are installed in the stope, generally parallel to the mining face and in accordance with a predetermined pattern of rows, to provide hanging wall support in the central region of each panel. In addition, roof bolts and/or backfill (not illustrated) may also be installed at predetermined positions to provide further hanging wall support.

In the face area 24 of each stope panel, situated between the first row 26 of props and the mining face, the normal sequence of mining operations is carried out, i.e. blast holes are drilled in the mining face, the blast holes are charged with explosive, the explosive is detonated, and broken rock is moved down dip, i.e. in the direction in which the reef dips downwardly, into the gullies from where it is removed from the mine working.

In accordance with the present invention, as indicated in the central panel in Figure 1, the conventionally used pack-type mine supports 20 are replaced by elongate, inflatable bags 28 which are placed end to end as illustrated. The props 22 in the first row 26 are replaced by similar bags 30 in end to end relationship.

The bags 28 and 30 are made of robust, flexible material which cannot easily be punctured by sharp projections on the footwall and hanging wall. Figure 2 illustrates one possible bag construction. The bag 28, 30 seen in Figure 2 comprises an elongate tube of suitably reinforced flexible material, typically rubber reinforced by internal steel wires or cords. The ends of the tube are sealed together by clamps 31. At one end, an inflation nozzle 32 extends into the interior of the bag. The nozzle is fitted with a non-return valve.

In use, compressed air is charged into the bags 28 and 30 through the inflation nozzles 32. The air inflates the bags and expands them transversely into contact with the hanging wall 18. In practice, inflation may be by air alone. Alternatively, the bags may be inflated at least partially with a liquid, typically water and possibly a fluent backfill slurry.

In the case of air inflation the bags 28 and 30 are typically inflated with compressed air from the same source which is normally used to provide compressed air to pneumatically powered equipment, such as rock drills, in the mine working. The inflation pressure, which can easily be monitored and if necessary varied, is such that each bag provides a predetermined level of hanging wall support along its length.

Referring to Figure 1, the bags 28 are placed close to one another in end to end relationship so as to form substantially continuous walls extending along the length of the gullies and along the edge of the face area 24. Thus, in combination with one another the bags 28 and 30 provide generally continuous barriers which separate the areas in which mine personnel are still working, namely the face areas 24 and gullies 14, from the areas in which little or no further work is conducted, namely mined out areas 36. In Figure 1 it will be seen that the bags 28 and 30 form generally continuous passages 34, extending along the gullies and across the mining face, to allow personnel access to these areas. If additional personnel access passages between the gullies 14 are required at any position, the hanging wall adjacent to such additional passages can be supported by inflated bags, in a manner similar to that used for the support of the hanging wall in the vicinity of the gullies 14 serving the central panel.

Particularly in deep level mines, ventilating air is required to ventilate and cool those areas of the stope in which personnel are working, i.e. the gullies and the face area. In accordance with the present invention, the required amount of ventilating air is delivered into the passages 34 in preference to the mined out area 36 of the stope where personnel are no longer active, i.e. those areas where personnel are actually working are preferentially ventilated.

This is achieved by the action of the bags 28 and 30 which act as ventilation barriers to separate areas requiring primary ventilation from areas requiring no, or less, ventilation. It is believed that selective ventilation of only the relevant areas, or at least preferential ventilation of those areas, as opposed to the whole mine working, will considerably reduce the volume of ventilating air which is required in the mine working.

It also be appreciated that although it would be desirable and most efficient for the bags 28, 30 to seal perfectly against one another and against the hanging wall and footwall, this may not always be attainable in practice given the often extremely rough and uneven nature of the footwall and hanging wall. However even if there is some leakage of air out of preferentially ventilated area, this should not be too detrimental and there will still be an overall reduction in the air requirement. While Figure 1 shows bags 28 and 30 used only in the central panel, such bags will be used throughout the mine working to form ventilation barriers and provide hanging wall support at required locations.

The bags 30 are close to the mining face and could possibly be damaged by rock fragments blasted from the face. For this reason, these bags may be fitted with particularly tough coverings on those surfaces which face the blast. Alternatively, these bags may have attachment points from which appropriate blast curtains can be suspended to protect the bags during blasting.

After each round of blasting and clearing, the bags 30 can be deflated and leapfrogged forwardly to new positions adjacent the new position of the mining face. Depending on the support requirements for the mined out area 36, a row of conventional props can then be installed in positions previously occupied by the bags. Alternatively, the mined out area 36 can be left unsupported to allow for stope closure and possible caving, or it can be filled with any other support medium, such as backfill, hydraulic fill, waste rock or the like.

In the latter cases, inflated bags can be left in position to serve a useful function in restraining the backfill or other support material.

Similarly, as the gullies extend in length as mining proceeds, further bags 28 can be added as required to the end of the existing bags to ensure the continuity of the ventilation barrier and adequate hanging wall support. Apart from the fact that the system of the invention can be expected to improve the overall economics of the mining operation, it will be understood that the compressibility of the air with which the bags are inflated in the preferred embodiment will allow the bags to yield as required as the hanging wall closes towards the footwall. Also, the compressibility of the air and the flexibility of the bags will ensure that the inflated bags are able to deform as necessary to conform to the uneven shape of the hanging wall and footwall. Still further, the bags will retain their support capabilities under seismic shock loading conditions, and will allow a uniform load distribution at the bag/hanging wall and bag/footwall interfaces, thereby ameliorating the hazards associated with fracture of the hanging wall and/or footwall failure.

Claims

A method of providing support and controlled ventilation in a mine working, the method comprising the steps of positioning inflatable bags adjacent one another in the mine working and inflating the bags to form mine supports extending between the footwall or floor of the mine working and the hanging wall or roof thereof, the bags being positioned in relation to one another so as to form, in combination and when inflated, ventilation barriers which separate previously mined zones of the mine working from active zones in which mining activities are being conducted, and delivering ventilating air at least primarily to the active zones.

2.

A method according to claim 1 wherein the mine working has a mining face and includes a series of panels along the mining face with gullies transverse to the mining face between adjacent panels, the method comprising the steps, in each panel, of positioning and inflating bags to form ventilation barriers extending alongside the gullies and across the mining face thereby to separate an active zone of the panel, which includes the gullies and the vicinity of the mining face, from the remainder of the panel, and of delivering ventilating air at least primarily to the active zone.

.

A method according to claim 2 comprising the step of suspending blast curtains from the bags at least where the ventilation barrier extends across the mining face.

4.

A method according to claim 2 or claim 3 wherein, after blasting and clearing operations have been carried out at the mining face and the mining face has advanced accordingly, those bags forming the ventilation barrier where it extends across the mining face are deflated and advanced in the mining direction to keep pace with the advance of the mining face.

5.

A method according to any one of the preceding claims wherein the bags are of flexible, elongate construction and are positioned end to end to form the ventilation barriers.

6.

A method according to any one of the preceding claims wherein the bags are at least partially inflated with air.

7.

A method according to claim 6 wherein the bags are inflated partially with air and partially with a liquid.

8.

For use in a method according to any one of the preceding claims, an inflatable bag comprising a hollow, elongate, flexible tube having a transverse dimension selected, when the tube is inflated, which is sufficient to extend between the hanging wall or roof and the footwall or floor of the mine working, clamps which clamp the ends of the tube closed to form an enclosure, and an inflation inlet into the enclosure controlled by a non-return valve.