AU4351199A - Method and apparatus for providing a stopping in an underground mine - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address of Service: WILSON MINING SERVICES PTY LIMITED WILSON, David William BALDWIN SHELSTON WATERS MARGARET STREET SYDNEY NSW 2000 METHOD AND APPARATUS FOR PROVIDING A STOPPING IN AN UNDERGROUND MINE Invention Title: Details of Associated Provisional Application No. PP6815 dated 11 August, 1998 The following statement is a full description of this invention, including the best method of performing it known to me/us:- -2- METHOD AND APPARATUS FOR PROVIDING A STOPPING IN AN UNDERGROUND MINE This invention relates to a method of and apparatus for providing a stopping across a roadway or the like in an underground mine and has been devised particularly though not solely to control the unwanted flow of air through fissures in the rock around the periphery of the stopping.

In this specification, where the term "stopping" is used it is to be understood to also refer to equivalent forms of passageway blocking devices used for equivalent purposes, such as "seals" used to close off disused mine areas.

There are many instances where it is necessary to provide a "stopping" across a roadway or other underground passage in a mine to prevent the flow of air along that roadway. Such stoppings are typically used to provide for ventilation within the mine such that air can enter the mine through an opening in the surface area and be sucked through predetermined passageways to an exhaust fan before being retumrned to the atmosphere. In order to achieve the desired flow pattemrn for air, it is commonly necessary to block off certain passageways that have been formed in the mining operation using stoppings.

S 20 In the past, stoppings have typically been formed by bricking up the passageway using conventional bricks or concrete blocks. Stoppings of this type have two major disadvantages. Firstly, the stopping is inclined to crack when distorted due to pressure from the roof, floor or side walls due to movement in the mine from subsequent mining operations, or from natural earth *o 25 settlement. These cracks allow air to leak from the high pressure to the low pressure side of the stopping and render the stopping partially ineffective.

Secondly, the roof and floor, and particularly the side walls of a roadway are inclined to crack or form fissures during the mining operation due to natural underground compressive forces or earth movement, or to the compressive and 3 0 shearing forces exerted by the mining machinery. In such situations, which are particularly prevalent in coal mines, air under pressure from a ventilation system tends to leak around the edges of a stopping through the fissures in the adjacent surfaces, even when the stopping itself is intact and air tight.

-3- In one aspect the present invention therefore provides apparatus for providing a stopping across a roadway or the like in an underground mine, said apparatus comprising an air flow resistant membrane extending across the roadway from side to side and from roof to floor and further extending into a peripheral slot cut into the roof, floor and sides of the roadway, and a resin seal substantially filling the peripheral slot and bonding the internal faces of the slot to the peripheral edges of the membrane.

Preferably the membrane comprises a flexible or semi-flexible membrane formed from sheet material.

Preferably the sheet material is located within the peripheral slot by way of suitable clips.

Preferably the resin seal comprises a polyurethane material pumped into the slot using a suitable nozzle once the flexible membrane has been positioned with its periphery within the slot.

In a further aspect the present invention provides a method of providing a stopping across a roadway or the like in an underground mine, said method comprising the steps of cutting a continuous slot into the roof, floor and sides of the roadway around the periphery of the intended location of the stopping, ~providing an air flow resistant membrane across the roadway such that the edges of the membrane are aligned with the continuous slot, casting a liquid resin into the slot such that the resin bonds with the intemrnal faces of the slot and also with the membrane, and allowing the resin to set.

In one form of the invention the air flow resistant membrane comprises a wall of resin material cast in place between two surfaces of suitable formwork.

25 The suitable formwork may comprise brick work or block work which is left in place after the resin membrane has set.

.*Preferably the resin membrane extends into the continuous slot, bonding with the internal faces of the slot as referred to above.

In an alternative form of the invention the air flow resistant membrane is 0 formed from a suitable flexible or semi-flexible material and the step of "providing an air flow resistant membrane across the roadway such that the edges of the roadway align with the continuous slot", comprises inserting the peripheral edges of the fabric membrane into the peripheral slot before the liquid -4resin is cast into the slot.

Preferably the step of inserting the peripheral edges of the flexible membrane into the slot include temporarily securing the edges within the slot using suitable clips.

The flexible membrane may comprise any suitable air flow resistant material designed to meet the criteria of the Department of Mineral Resources Coal Mines Inspectorate, e.g. to pressure rating, durability, fire resistance, antistatic, etc. Such material may be a suitable woven or fibre reinforced fabric such as Brattice cloth or a metal mesh such as a woven or expanded mesh coated with a suitable flexible surface spray such as a polyacrylate spray to render the mesh air tight.

Notwithstanding any other forms that may fall within its scope, two preferred forms of the invention will now be described with reference to the accompanying drawings in which:- Fig. 1 is a diagrammatic plan view showing the typical placement of stoppings in an underground mine; Fig. 2 is a plan view to an enlarged scale of one end of the ventilation stopping according to the invention; Fig. 3A is a diagrammatic elevation across a mine roadway showing the cutting of a slot into the side of the roadway according to the invention; :•Fi ig. 3B is a cross-sectional elevation through the stopping according to one form of the invention; Fig. 3C is a cross-sectional plan view through the stopping shown in Fig.

3B; Fig. 4A is a cross-sectional elevation through a mine roadway showing an alternative form of stopping according to the invention; Fig. 4B is a cross-sectional elevation of the construction shown in Fig. 4A; and Fig. 4C is a cross-section to an enlarged scale showing the engagement 30 of the periphery of the stopping shown in Figs. 4A and 4B with the adjacent slot.

ooooo In an underground mine such as a coal mine of the type diagrammatically shown in Fig. 1, roadways 1 and 2 are commonly cut deep into the mine using various types of known mining machinery. During the mining operati6n further cross roadways 3 are commonly cut between the roadways 1 and 2 leaving coal pillars 4 to support the roof of the mine and preventing collapse of the mine.

In providing ventilation to the mine, it is necessary to provide "stoppings" such as those shown at 5 to seal off the cross roadways 3 from air flow. Once the mine is sealed in this manner, exhaust fans 6 placed at the entrance to roadway 2 can be used to draw air into the mine and down roadway 1 as shown by arrows 7 where it can recirculate deep in the mine and return as shown by arrows 8 down roadway 2 to the exhaust fan 6. Any leakage of the stoppings 3 significantly reduces the effectiveness of the ventilation in the mine.

In order to enhance the performance of the stoppings in a mine, the present invention provides for the cutting of a slot 9 (Fig. 2) into the coal face around the periphery of the intended location of the stopping 11. Although Fig. 2 is a cross-sectional plan view showing a side wall 10,. the view is equally applicable to the roof and floor of the roadway in the vicinity of the ventilation stopping 11.

During the mining operation, particularly in coal mines, a zone of broken coal 12 is formed adjacent the face 10. The zone is typified by a number of fissures shown diagrammatically at 13 which permit air leakage through the coal to the depth of the broken zone 12. Such fissures allow air leakage around the periphery of a stopping when constructed according to conventional (prior art) techniques.

The present invention therefore provides for the cutting of a slot 9 to a depth in the coal face which is greater than the depth of the zone of broken coal 12 so that the end 14 of the slot extends into the zone of more solid coal Once the slot has been cut, typically by using a compressed air driven chainsaw with suitable rock cutting teeth, the slot is filled with a liquid resin 16 which then is allowed to set and bond to both the intemal faces of the slot 9 and to the peripheral edge of the ventilation stopping 11.

In one form of the invention as shown in Figs. 3A, 3B and 3C, the 30 ventilation stopping is formed from an air flow resistant membrane in the form of .ooooi a cast insitu core 17 formed between formwork faces 18. The formwork faces may take any suitable form but are typically permanent formwork provided by concrete block walls which remain in place as a permanent part of th6 stopping.

-6- The core 17 may be formed of any suitable material which is preferably flexible in nature so as to remain air tight upon deformation of the floor 21, roof 19 or side walls 20 of the roadway. To this end the core 17 is typically a polyurethane resin which may be mixed with gravel forming a so-called pur/gravel core. As this core is cast insitu, the core can simply extend into the slots 9 formed around the periphery of the roadway such that the core and the polyurethane material extending into the slots 9 form a continuous air tight membrane that extends not only across the roadway but through the zone of broken coal and into the zone of more solid coal as previously described with reference to Fig. 2.

Fig. 3A also shows diagrammatically a method of cutting the slots into the side walls of the roadway using a compressed air driven chainsaw 22 having a cutting bar 23 provided with suitable rock cutting teeth on the chain and mounted on an upright prop 24 which is wedged between the roof 19 and the floor 21 and may be provided with a suitable drive mechanism to drive the chainsaw vertically on the prop 24. The mechanism can also be adapted to cut suitable slots in the roof 19 and floor 21 to provide a continuous peripheral slot around the edge of the stopping.

Another alternative form of the invention is shown in Figs. 4A, 4B and 4C wherein the air flow resistant membrane of the stopping is formed from a flexible 2 0 or semi-flexible fabric 25 extending across the roadway between the roof 19 and the floor 21 and the side walls 20. The fabric may be any suitable air flow resistant material such as a woven cloth material Brattice cloth) or any o. ther suitable form of flexible material meeting the requirements for use in mines pressure rating, durability, fire resistance, anti-static, etc). The fabric could also be a metal mesh such as a woven or expanded mesh which is placed as described below and then coated with a flexible surface spray, e.g. a polyacrylate to give the necessary resistance to air flow.

this form of the invention, the peripheral slot is cut as previously described and the periphery of the fabric 25 inserted into the slot 9 where it can 30 be folded over and temporarily held in place by suitable clips 26. The clips may take any suitable form but are typically metal or plastics clips of a V configuration inserted into a folded portion at the edge of the fabric 25 so as to hold the edge of the fabric temporarily located within the slot 9.

-7- The slot is then filled with liquid resin 16 and allowed to set or cure. Once again the liquid resin may be any suitable material but is typically a polyurethane material pumped into the slot using a suitable application nozzle. The polyurethane, when set bonds to the side walls 27 of the slot 9 and to the air resistant fabric membrane 25 in the vicinity of the slot providing an air flow resistant stopping across the roadway, extending into the air leakage prone zone of broken coal or rock around the periphery of the stopping.

In this manner, a stopping can be provided in a mine which is simple and relatively inexpensive to provide and erect while yet being effective in controlling air flow through the roadway and also through the fractured coal or other rock around the periphery of the roadway. Furthermore a stopping of this type can easily be created from a flexible or semi-flexible material which will allow for deformation of the roof, floor or walls of the mine in the vicinity of the stopping, without cracking or fracturing and allowing air to pass through the stopping.

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Claims (12)

1. A method of providing a stopping across a roadway or the like in an underground mine, said method including the steps of cutting a continuous slot into the roof, floor and sides of the roadway around the periphery of the intended location of the stopping, providing an air flow resistant membrane across the roadway such that the edges of the membrane are aligned with the continuous slot, casting a liquid resin into the slot such that the resin bonds with the internal faces of the slot and also with the membrane, and allowing the resin to set.

2. A method as claimed in claim 1 wherein the air flow resistant membrane is formed from a suitable flexible or semi-flexible material and the step of "providing an air flow resistant membrane across the roadway such that the edges of the roadway align with the continuous slot", includes inserting the peripheral edges of the membrane into the peripheral slot before the liquid resin is cast into the slot.

3. A method as claimed in claim 2 wherein the step of inserting the peripheral edges 15 of the flexible membrane into the slot includes temporarily securing the edges within the oo slot using suitable clips.

4. A method as claimed in claim 3 wherein the resin comprises a polyurethane °o material pumped into the slot using a suitable nozzle once the flexible membrane has ooo been positioned with its periphery within the slot. 20

5. A method as claimed in claim 1 wherein the air flow resistant membrane includes a wall of resin material cast in place between two surfaces of suitable formwork.

6. A method as claimed in claim 5 wherein the suitable formwork comprises brick work or block work which is left in place after the resin membrane has set.

7. A method as claimed in either claim 5 or claim 6 wherein the resin membrane extends into the continuous slot, bonding with the internal faces of the slot as referred to above.

8. Apparatus for providing a stopping across a roadway or the like in an underground mine, said apparatus including an air flow resistant membrane extending across the roadway from side to side and from roof to floor and further extending into a peripheral slot cut into the roof, floor and sides of the roadway, and a resin seal substantially filling the peripheral slot and bonding the internal faces of the slot to the peripheral edges of the membrane.

9. Apparatus as claimed in claim 8 wherein the membrane comprises a flexible or semi-flexible membrane formed from sheet material.

Apparatus as claimed in claim 9 wherein the sheet material is located within the peripheral slot by way of suitable clips.

11. Apparatus as claimed in any one of claims 8 to 10 wherein the resin seal includes a polyurethane material pumped into the slot using a suitable nozzle once the flexible membrane has been positioned with its periphery within the slot.

12. A method of providing a stopping across a roadway or the like in an underground mine, substantially as described herein with reference to the accompanying drawings. S••13. Apparatus for providing a stopping across a roadway or the like in an underground mine, substantially as described herein with reference to the accompanying drawings. DATED this 1 1th day of August, 1999 WILSON MINING SERVICES PTY LIMITED Attorney: JOHN D. FORSTER Fellow Institute of Patent and Trade Mark Attorneys of Australia of BALDWIN SHELSTON WATERS