UNDERGROUND MINE VENTILATION CURTAIN OR BARRIER

Abstract

A mine ventilation curtain (1, 20) is provided comprising, in the operative condition, a generally upright curtain or barrier extending from a foot wall (4) in an underground mine to an overhanging hanging wall (5, 25). The curtain has a foot wall compartment (3, 22) of a flexible sheet material with the footwall compartment being operatively filled with a suitable optionally settable fluent material (13, 27) such that the lower edge of the curtain or barrier substantially adopts an undulating shape of the adjacent foot wall. The fluent material is selected from a suitably heavy liquid and an optionally settable slurry of grout or backfill material. The mine ventilation curtain may be a flexible ventilation curtain (2) extending upwards from the foot wall compartment (3) and having its uppermost edge held in close association with the hanging wall. Alternatively, the mine ventilation curtain may be a generally rigid ventilation barrier (20) in the form of longitudinal segments each of which comprises a series of optionally interconnected superjacent compartments (22, 23, 24) extending from the footwall to the hanging wall with the uppermost compartment (24) adopting an undulating shape of the adjacent hanging wall.

Description

FIELD OF THE INVENTION

This invention relates to underground mine ventilation curtains or barriers and, in particular, but not exclusively, to in-stope ventilation control curtains or barriers used for creating ventilation passages between the hanging wall and foot wall in a mine stope.

In this specification is to be understood that the term the ventilation curtain is intended to include flexible ventilation curtains and generally rigid ventilation barriers.

BACKGROUND TO THE INVENTION

In the operation of a typical large tabular ore body in an underground mine, ventilation in the form of the provision of fresh, cool air to the entire extent of the mine workings is essential. The nature of the tabular ore deposits results in wide narrow mining stopes with vast worked-out back areas, which, if left open, waste large amounts of air cooling them unnecessarily.

The flow of fresh air through a mine is required for two principal reasons, firstly, to provide an acceptable climatic working environment for all underground personnel, and, secondly, to flush toxic fumes resulting from explosive blasts and any airborne combustion products in the event of underground fires out of the mine.

The necessary ventilation is typically generated by extractor- and/or compressor fans by way of a carefully designed network of shafts and tunnels and thence through the working areas. Ventilation of dead-ends, such as development ends, is generally provided by means of blower fans through dedicated ducting.

The ventilation of a mine is reported to account for one the largest proportions of a mine's energy consumption. In order to prevent expensive waste, stope back areas are closed off to air flow by means of ventilation curtains or barriers.

Ventilation curtains have been used for a very long time. Generally, modern flexible ventilation curtains consist of a geotextile that is suspended from mine support units that are spaced apart in the normal course of events. One of the main problems with conventional flexible ventilation curtains is air leakage above and below the curtain where gaps are left between the upper and lower edges of the curtain and to the irregular hanging wall and footwall.

OBJECT OF THE INVENTION

It is an object of this invention to provide a mine ventilation curtain that overcomes, at least to some extent, leakage problems of the general type indicated above.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a mine ventilation curtain comprising, in the operative condition, a generally upright curtain extending from a foot wall in an underground mine to an overhanging hanging wall, the curtain being characterised in that the lower region thereof in contact with the foot wall is defined by a foot wall compartment of a flexible sheet material with the footwall compartment being operatively filled with a suitably heavy optionally settable fluent material such that the lower edge of the curtain or barrier substantially adopts an undulating shape of the adjacent foot wall.

Further features of the invention provide for the fluent material to be either a liquid or a slurry of grout or backfill material and; for the flexible sheet material to be permeable material for allowing water of a slurry introduced into the foot wall compartment to escape whilst retaining solid particulate material therein, the flexible sheet material typically being a geotextile material or a suitable membrane; and for the particulate material optionally to be a settable material, typically a cementitious grout.

In a first variation of the invention a generally flexible ventilation curtain extends upwards from the foot wall compartment and has its uppermost edge held in close association with the hanging wall by any suitable means according to circumstances. In a preferred arrangement, a tension member extends along the uppermost edge of the flexible ventilation curtain, typically within a seam formed along such edge and the upper edge of the flexible curtain may be held against the hanging wall in at least some recessed areas thereof by means of spring loaded or other lightweight telescopic props. The uppermost edge of the flexible ventilation curtain may also be provided with eyelets suitable for receiving anchor bolts passing therethrough for attachment to the hanging wall. Of course, combinations of props and anchor bolts may be used as well as any other suitable support means.

In a second variation of the invention a generally rigid ventilation barrier is in the form of longitudinal segments each of which comprises a series of optionally interconnected superjacent compartments extending from the footwall to the hanging wall with the uppermost compartment adopting an undulating shape of the adjacent hanging wall. The footwall compartment is preferably the widest with superjacent compartments decreasing in width so that, in cross-section, the generally rigid ventilation barrier has a wide base and appreciably narrower upper edge so as to render it free standing on an inclined foot wall. Preferably all of the compartments are interconnected and a filler inlet, preferably a nonreturn filler valve, is provided preferably in an upper region thereof, typically the uppermost compartment.

The invention also provides, in the uninstalled condition and as an article of commerce, a flexible ventilation curtain having a footwall compartment formed along one edge thereof and means along the opposite edge for in enabling it to be held against a hanging wall, in use, the ventilation curtain being adapted to form, in the operative condition, a ventilation curtain as defined above.

The invention still further provides, in the uninstalled condition and as an article of commerce, a barrier member comprising a series of interconnected flexible compartments and at least one filler inlet, the barrier member being adapted to be inflated by filler material to form, in the operative condition, a generally rigid ventilation barrier as defined above.

In order that the invention may be more fully understood one embodiment of each of the two variations thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:—

FIG. 1 is a schematic section taken through a flexible ventilation curtain according to the first variation of the invention;

FIG. 2 is a schematic front elevation of a length of such ventilation curtain;

FIG. 3 is a schematic plan view showing one possible arrangement of a flexible ventilation curtain relative to a series of support packs in a mine stope;

FIG. 4 is a schematic section taken through a generally rigid ventilation barrier according to the second variation of the invention;

FIG. 5 is a schematic front elevation of a length of the ventilation barrier illustrated in FIG. 4; and,

FIG. 6 is a schematic plan view showing one possible arrangement of a series of ventilation barriers relative to a series of support packs in a mine stope.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In the embodiment of the first variation of the invention illustrated in FIGS. 1 to 3 a flexible mine ventilation curtain, generally indicated by numeral (1), comprises, in the operative condition, a generally upright curtain (2) extending from a foot wall compartment (3) that engages the footwall (4) in an underground mine to an overhanging hanging wall (5).

Both the curtain and footwall compartment are made of a water permeable flexible sheet material, typically a geotextile material or a suitable membrane, and the footwall compartment could be made by stitching the sheet material back upon itself to provide a suitable cross-sectional size of footwall compartment. The flexible sheet material is selected so that it allows water to pass through it whilst retaining solids such as a cementitious grout or backfill material within the footwall compartment. The footwall compartment has a nonreturn inlet valve (6) for the introduction of slurry into the compartment.

The ventilation curtain extends upwards from the foot wall compartment and has its uppermost edge (7) held in close association with the hanging wall. In this embodiment of the invention a tension member (8) extends along the uppermost edge of the ventilation curtain in a large seam (9) formed along such edge. The seam is large enough to enable the upper edge of the curtain to be held against the hanging wall in at least some recessed areas thereof by means of spring loaded or other lightweight telescopic props (10). The uppermost edge of the ventilation curtain may, in addition, or in the alternative, be provided with eyelets (11) suitable for receiving anchor bolts passing therethrough for attachment to the hanging wall or to stope support units. Of course combinations of props and anchor bolts may be used as well as any other suitable support means.

As indicated above, the invention extends to the uninstalled ventilation curtain and, such a curtain is installed by suspending its upper edge from the tension member that itself can be attached to the upper ends of support packs (12), as shown in FIG. 3. Slurry of a suitable grout or backfill material (13) is then introduced into the footwall compartment so that the lower edge of the curtain substantially adopts the undulating shape of the adjacent foot wall thereby forming an effective closure therewith. The upper edge of the flexible ventilation curtain can then be attached to the recessed areas of the hanging wall by means of lightweight props and/or anchor bolts to form an effective closure therewith. As shown in FIG. 3, the ventilation curtain can be of a zigzag shape between adjacent support packs. However, it could also extend on one side of the support packs.

Turning now to the second variation of the invention that is illustrated in FIGS. 4 to 6, a generally rigid ventilation barrier, generally indicated by (20) is formed in longitudinal segments each of which extends between two adjacent support packs (21), as shown in FIG. 6. Each segment comprises a series of, in this instance four, interconnected superjacent compartments starting at the footwall compartment (22) with two intermediate compartments (23) and an uppermost compartment (24) adopting the undulating shape of the adjacent hanging wall (25).

The footwall compartment is the widest with superjacent compartments decreasing in width so that, in cross-section, the barrier has a wide base and an appreciably narrower upper edge. This construction lowers the centre of gravity and renders the barrier free standing on an inclined footwall whilst also saving on materials and erection time. The uppermost compartment (24) is provided with a nonreturn filler valve (26).

As will be clear from the aforegoing the barrier segments are erected by introducing a slurry of grout or backfill material (27) into the nonreturn filler valve. The slurry flows downwards to firstly fill the footwall compartment with the lower wall deforming to adopt the undulating shape of the footwall and thereafter inflates the superjacent compartments and finally the uppermost compartment the uppermost wall of which also deforms to adopt the undulating shape of the hanging wall.

It will be understood that numerous variations may be made to the embodiments of the invention described above without departing from the scope hereof. In particular, the footwall compartment, and indeed the superjacent compartments in the instance of the ventilation barrier, need not be made of a permeable material but could be, for example, waterproof in which instance water may be used as a fluent heavy material.

It is also within the scope of the invention that compressed air could be used to inflate a barrier segment of the type described above. Of course, the advantage of using a non-setting fluent material is that the barrier segments can be deflated and reused should this be practicable.

Claims

1. A mine ventilation curtain (1, 20) comprising, in the operative condition, a generally upright curtain or barrier extending from a foot wall (4) in an underground mine to an overhanging hanging wall (5, 25), the curtain being characterised in that the lower region thereof in contact with the foot wall is defined by a foot wall compartment (3, 22) of a flexible sheet material with the footwall compartment being operatively filled with a suitable optionally settable fluent material (13, 27) such that the lower edge of the curtain or barrier substantially adopts an undulating shape of the adjacent foot wall.

2. A mine ventilation curtain as claimed in claim 1 in which the fluent material is selected from a suitably heavy liquid and a slurry of grout or backfill material.

3. A mine ventilation curtain as claimed in claim 2 in which the flexible sheet material is a permeable material for allowing water of a slurry introduced into the foot wall compartment to escape whilst retaining solid particulate material therein.

4. A mine ventilation curtain as claimed in any one of the preceding claims in which the particulate material is a settable material.

5. A mine ventilation curtain as claimed in any one of the preceding claims in which the ventilation curtain is a flexible ventilation curtain (2) extending upwards from the foot wall compartment (3) and having its uppermost edge held in close association with the hanging wall.

6. A mine ventilation curtain as claimed in claim 5 in which the uppermost edge (7) of the flexible ventilation curtain is held in close association with the hanging wall (5) by a tension member (8) extending along the uppermost edge of the ventilation curtain.

7. A mine ventilation curtain as claimed in either one of claim 5 or 6 in which the uppermost edge of the ventilation curtain has a seam (9) formed therealong and the upper edge of the curtain is held against the hanging wall in at least some recessed areas thereof by means selected from spring loaded or other lightweight telescopic props (10) and eyelets (11) suitable for receiving anchor bolts passing therethrough.

8. A mine ventilation curtain as claimed in any one of claims 1 to 4 in which the ventilation curtain is a generally rigid ventilation barrier (20) in the form of longitudinal segments each of which comprises a series of optionally interconnected superjacent compartments (22, 23, 24) extending from the footwall to the hanging wall with the uppermost compartment (24) adopting an undulating shape of the adjacent hanging wall.

9. A mine ventilation curtain as claimed in claim 8 in which the footwall compartment (22) is the widest with superjacent compartments (23, 24) decreasing in width so that, in cross-section, the barrier has a wider base and an appreciably narrower upper edge thereby rendering it free standing on an inclined foot wall.

10. A mine ventilation curtain as claimed in either one of claim 8 or 9 in which all of the compartments are interconnected and a filler inlet valve (26) is provided.

11. A flexible mine ventilation curtain in the uninstalled condition and having a footwall compartment formed along one edge thereof and means along the opposite edge for enabling it to be held against a hanging wall, in use, the ventilation curtain being adapted to form, in the operative condition, a ventilation curtain as claimed in any one of claims 5 to 7.

12. A mine ventilation barrier segment in the uninstalled condition comprising a series of interconnected compartments and at least one filler inlet, the barrier member being adapted to be inflated by filler material to form, in the operative condition, a ventilation barrier as claimed in any one of claims 8 to 10.