AU2009201159A1 - Flexible Mine Seal - Google Patents

Description

mcinnes patents AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Applicant: Resco Underground Services Pty Limited 4-8 Karoonda Close Rathmines NSW 2283 Actual Inventors: Brian McCowan 4-8 Karoonda Close Rathmines NSW 2283 Vince Martin 4-8 Karoonda Close Rathmines NSW 2283 Address for Service: HODGKINSON McINNES PATENTS Patent & Trade Mark Attorneys Levels 21, 201 Elizabeth Street Sydney NSW 2000 Invention Title: Flexible Mine Seal Details of Priority AU 2008901473 Application: Filed 27 March 2008 HMcIP Ref: P20800AU02 2 Flexible Mine Seal Technical Field The present invention relates to a flexible mine seal and particularly, but not exclusively to a flexible mine seal for coal mines. Background Art When extracting coal from coal mines it is necessary to drive a minimum of two spaced apart passages (roadways) connected by cross passages (cut throughs). One roadway is used to provide a forward ventilation path (intake) to the active mining face, while the other carries the air from the active face to a main return airway, and is itself referred to as a return roadway. In order to facilitate the correct air flow, the cross passages are closed by a ventilation control device known as a ventilation stopping or seal. The roadways are also sealed with permanent, or at least semi-permanent mine seals. There is a need for improved safety standards in mining, particularly in ventilation, which has the most important function in preventing and controlling the build-up of flammable mixtures of gases, spontaneous combustion and sealing worked out areas (goafs). In addition, good ventilation enables the provision of a cool, dust free and healthy environment for mine workers. In the past, both stoppings and seals have been provided by means of semi-rigid and rigid types in the mine passage way. Such stoppings and seals are classified as static stoppings and seals and have been found to be unsatisfactory because firstly they are expensive to install, and secondly if there is movement of the strata such as floor heave or roof movement, the rigid stoppings and seals can crack. This, in turn, requires further costs to repair and reseal to maintain their integrity. Leakage in the air flow due to 3 cracking of rigid stoppings and seals is one major cause of loss of ventilation and increased risk of spontaneous combustion and gas emissions. In an attempt to provide improved stoppings, there has been previously proposed the use of flexible sheet material ventilation stoppings, which are held across the passage way. One particular example is shown in Australian patent no. 768757 entitled "Total Seal Ventilation Control Device" in the name of Fleity Pty. Limited. That patent describes mine passage ventilation stoppings having a flexible sheet, strapping, a plurality of strata engaging fastening means and a compressible flexible perimeter seal material. The flexible sheet is fire resistant, substantially antistatic and is configured to span the mine passage. The strapping is adapted for overlaying and securing the perimeter edges of the flexible sheet to the walls, roof, and floor of the mine passage. The strata engaging fastening means are adapted to hold the strapping and flexible sheet in place. After panels have been completed in a mine, it is necessary to install permanent mine seals to prevent or control the build up flammable mixtures of gases and reduce the risk of spontaneous combustion. Similar to conventional mine stoppings, these permanent mine seals have traditionally been provided by means of semi-rigid or rigid construction. Accordingly, there is a need to provide improved mine seals. This would overcome at least some of the disadvantages of previously known approaches in this field, and would provide a useful alternative. Disclosure of Invention According to a first aspect of an embodiment of the present invention there is provided a mine passage ventilation seal comprising first and second 4 ventilation stoppings, which are spaced apart from each other defining a void therebetween, the void being at least partially filled with a compressible material and having a geogrid catenary secured to the roof and floor of the mine passage therein. Preferably, the geogrid catenary is bolted to the roof and floor of the mine passage. Preferably, the compressible material is expandable foam, most preferably urea silicate. The geogrid catenary is preferably substantially of polyester (PET). The first and second ventilation stoppings preferably include a fire resistant, substantially antistatic flexible sheet to span the mine passage. Preferably, the first and second ventilation stoppings are adapted to be secured to the walls, roof and floor of the mine passage so as to seal any spaces between the compressible flexible sheeting and walls (ribs), roof, floor and variations of the mine passage that may exist or occur after the stopping is assembled across the mine passage. In this specification, unless the context clearly indicates otherwise, the term "comprising" has the non-exclusive meaning of the word, in the sense of "including at least" rather than the exclusive meaning in the sense of "consisting only of". The same applies with corresponding grammatical changes to other forms of the word such as "comprise", "comprises" and so on. Brief Description of the Drawings Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: FIG 1 shows a transverse cross sectional view showing one stopping of a first embodiment of the seal of the present invention fitted in a mine roadway.

5 FIG 2 shows a transverse cross sectional view of a second embodiment of the seal of the present invention fitted in a mine passage way heading of a mine; FIG 3 shows a longitudinal cross-sectional view of the embodiment of the seal shown in FIG 2; and FIG 4 shows an enlarged longitudinal cross-sectional view of region "A" depicted in FIG 3. Best Mode for Carrying Out the Invention The present invention generally relates to a flexible mine seal and particularly, but not exclusively to a mine seal for coal mines wherein two flexible stoppings and a geogrid reinforcement catenary are erected and the void formed between the two stoppings is filled with a compressible material. The flexible mine seal comprises a compressible material sandwiched between at least two flexible stoppings. The flexible stoppings are erected in a passageway of a mine, such as a roadway, and the flexible stoppings form a void or cavity therebetween. A high strength mine geogrid catenary is then bolted to the roof and floor. The void or cavity formed between the two stoppings is then filled with a compressible material to form the flexible mine seal. The geogrid provides the structural strength for the mine seal. Referring to both FIGS 1 and 2, it can be seen that the stopping referred to generally by numeral 1 spans the passageway of a mine being, for example, a heading 2. It is clear that the seal can span other types of passages in a mine and is not limited to headings only. The stopping 1 has a flexible fire resistant substantially antistatic sheet 3. One particularly suitable seal sheeting is described in Australian patent no. 768757 entitled "Total Seal Ventilation Control Device" in the name of Fleity Pty. Limited. The seal sheeting in 6 Australian patent no. 588418 entitled "Ventilation Stopping Curtain" in the name of Fleity Pty. Limited is also suitable to be used in the present invention, as are other types of sheeting 3. The passageway or heading has been shown within the strata and is indicated by numeral 2. Typically therefore, the passageway or heading 2 has walls (ribs) being side walls 4 and a roof 5 and a floor 6. The flexible sheeting 3 is secured by its perimeter edges to the walls 4, roof 5 and floor 6 of the mine passage 2. Strapping 7 and bolts 8 are used for this purpose. As best shown in FIG 4, the flexible mine seal 16 of the present invention comprises a first stopping la and a second stopping lb that are erected in a mine passageway or heading 2. A void or cavity is formed between the first and second stoppings la, 1b. Within the void, a reinforcing polymer geogrid catenary 13 is bolted to the roof and floor using a clamp 17. This is best shown in FIG 4. A compressible material, such as expandable foam 15 is then sprayed into the void which, upon contact with air, begins to expand and fill the void. Once the foam 15 has been sprayed into the void, it hardens to some extent, although once fully hardened, the foam remains compressible under pressure. Suitable foam 15 for this application is urea silicate, although any suitable type of compressible material may be utilised. In order to allow the expandable foam 15 to be sprayed into the void, a peripheral portion of at least one of the stoppings la, lb is left unsecured to the strata of the mine passageway or heading 2, thereby allowing the nozzle of the foam gun to be passed through the stopping and into the void. Once the void has been filled with the expandable foam 15, the nozzle of the foam gun is removed and the peripheral portion of the stopping la or lb is secured to the strata of the mine passage way 2 with strata engaging fastening means, preferably the strapping 7 and bolts 8. The geogrid matrix catenary 13, which is bolted to the roof and floor of the passageway or heading 2 within the void, provides the structural strength for the mine seal.

7 The flexible nature of the compressible material 15 allows for some deformation of the mine seal 16, if there is movement of the surrounding strata, such as floor heave or roof movement. This ensures that the integrity of the substantially airtight seal between the flexible mine seal 16 and the side walls 4, roof 5 and floor 6 of the mine passage way 2 is maintained. This also ensures that the flexible mine seal 16 does not crack or split if there is movement of the strata. The flexible nature of the compressible material 15 also increases the stress tolerance of the flexible mine seal 16 and, in the event of an explosion or large goaf fall, the flexible mine seal will absorb some of the energy from the explosion through lateral crushing of the compressible material, such as expandable foam. The geogrid matrix catenary 13 is a polyester (PET) geogrid, which is specifically designed for stabilization and reinforcement of the flexible mine seal 16. The combination of the stoppings la, 1b, the compressible material 15 and the geogrid matrix catenary 13 act together provide a flexible mine seal 16 that is suitably adapted to resist the forces generated in the event of an explosion or goaf fall. Whilst a polyester geogrid 13 is preferred, in other embodiments, other commercially available geogrids such as high density polyethylene (HDPE), polypropylene (PP) or steel (strips, mesh panels or ladders, refer steel reinforced walls section) can also be used. Whilst the compressible material 15 shown in the accompanying drawings is expandable foam, it should be understood that in other embodiments, not shown in the drawings, any other type of suitable material can be used to fill in the voids or cavities that are formed between adjacently spaced apart stoppings. It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or in any other country.

Claims (8)

1. A mine passage ventilation seal comprising first and second ventilation stoppings, which are spaced apart from each other defining a void therebetween, the void being at least partially filled with a compressible material and having a geogrid catenary secured to the roof and floor of the mine passage therein.

2. A mine passage ventilation seal of claim 1 wherein the geogrid catenary is bolted to the roof and floor of the mine passage.

3. A mine passage ventilation seal of claim 1 wherein the compressible material is expandable foam.

4. A mine passage ventilation seal of claim 2 wherein the expandable foam is urea silicate.

5. A mine passage ventilation seal of claim 1 wherein the geogrid catenary is substantially of polyester (PET).

6. A mine passage ventilation seal of claim 1 wherein the first and second ventilation stoppings include a fire resistant, substantially antistatic flexible sheet to span the mine passage.

7. A mine passage ventilation seal of claim 1 wherein the first and second ventilation stoppings are adapted to be secured to the walls, roof and floor of the mine passage so as to seal any spaces between the 9 compressible flexible sheeting and walls (ribs), roof, floor and variations of the mine passage that may exist or occur after the stopping is assembled across the mine passage.

8. A mine passage ventilation seal substantially as hereinbefore described with reference to any one or more of the accompanying drawings.