AU670193B2 - Apparatus for and method of water infusion in coalseams - Google Patents

Description

1 The present invention relates to water infusion in coalseams and.

in particular, to a method and apparatus for effecting same.

In underground coal mines where methane gas infusion is a problem, it is known to drain the methane gas from the coalseam prior to normal mining operations. Such predraining achieves a reduction of methane gas content by approximately 80-90%. It has also been found that the inherent moisture content of the coalseam which is approximately 1.5% in normal circumstances is reduced to less than as a result of the methane gas drainage.

This reduction in the moisture content of the coal creates dust problems during long wall mining activities. Dust is generated from the cutting action of the shearer drums, dumping of the coal onto the automatic feed conveyor, and breaking of coal at the crusher. Although water is applied during cutting and the crushing operations, it is not sufficient to control dust emissions into the ventilating air flow.

For this reason, water infusion of the coal prior to the mining operation is desirable to replace some of the moisture lost during the methane gas drainage.

It has been known to infuse water into the coal seam by sealing 20 the empty methane gas drainage holes which are redundant after the methane gas drainage. A simple method which has been used is to attach a water supply hose via a cap and valve to the end of the drainage hole stand pipe in a tail gate and attempt to block the other end of the holes in the main gate.

25 This method proved to be unsuccessful and difficulties were found in blocking the intersections of the holes and containing the water in the hole at both the main gate and the tail gate sides of the long wall block due to fissures in the ribs extending up to 12 m into the block.

.It was found that this method was unsuccessful since dust counts during the long wall mining continued to be high. For this reason, the method was abandoned.

In a subsequently devised method of water infusion via the methane drainage or bleed holes, an apparatus including a bag which was fitted to the end of a length of conduit tube was used to block the holes. The apparatus included a non-return valve inside the bag and a rubber grommet outside the bag. In practice, as a hole was intersected, a bag would be inserted into the hole to a required depth and the bag pumped full of grout via the conduit pipe. As the bag HRW/l1158c filled with grout it would expand and block off the hole. At a pressure of approximately 500 kPa, the relief grommet would blow out, enabling the grout to exit into the hole and backfill the hole to a desired length. This method had the advantages that firstly it prevented the suction of fresh air into the inseam drainage holes, and secondly, provided a blockage for water infusion purposes once methane drainagp was finished within the area.

One disadvantage with the aforedescribed method is that grout is required and the cost of the grout is substantial. The water infusion is usually set up during shutdown of the mining operations and therefore as the aforedescribed method is time consuming, it has been found that it is difficult to set up during these temporary shutdowns.

It is an object of the present invention to provide an improved method and apparatus of water infusion in coalseams which substantially overcomes or ameliorates the above mentioned difficulties.

According to one aspect of the present invention there is disclosed an apparatus for water infusion in coalseams, said apparatus comprising a pipe for insertion into a hole in said coalseam with a substantially annular space located between said pipe and the&surfcoof said hole, and said pipe having at least one water impervious bag surrounding a corresponding aperture in said pipe, said bag being sealingly clamped to said pipe and being in fluid communication with sa'd pipe via said aperture.

In a preferred embodiment, the pipe has a relief valve means connected thereto to release water from the pipe when the water pressure within the bag rises to a predetermined level.

According to another aspect of the present invention there is disclosed a method of water infusion in coalseams, said method ^comprising the steps of inserting into at least one hole in said coalseam a pipe to thereby create a substantially annular space located between said pipe and the urfae of said hole, said pipe having at least one water impervious bag surrounding a corresponding aperture in said pipe, said bag being sealingly clamped to said pipe and being in fluid communication with said pipe via said aperture; filling said bag with water via said pipe to a predetermined pressure whereby said bag expands to abut against the surface of said hole thereby substantially blocking said hole; and filling the hole with pressurized water on at t least one side of said bag whereby said bag blocks the -e 3 passage of said water in said hole, said water being infused under pressure into said coalseam at the blockage and along the length of the hole.

In a preferred embodiment a wetting agent can be added to the water if required.

Some embodiments of the present invention will now been described with reference to the drawings in which; Fig. 1 is a schematic diagram of a coalseam which has a plurality of bleed holes drilled therein, Fig. 2 is a longitudinal cross-sectional view of part of the apparatus of one embodiment of the present invention, and Fig. 3 is a longitudinal cross-sectional view of a relief valve connected to the pipe.

In a coal mine 1 as illustrated in Fig. 1, the coalseam 2 has a coal face 3 at which mining has been carried out. The rest of the coalseam 2 is known as virgin coal. Prior to mining of the virgin coal, a number of bleed holes 4 are drilled in a fan pattern into the coalseam 2. The bleed holes 4 are used to bleed any diffured methane gas in the coalseam 2. The bleed holes 4 are usually 200 m in length and have an internal diameter of 85 mm. The bleed holes 4 are connected to a pipe line (not illustrated) and a number of suction e. pumps (not illustrated) are used to provide a partial vacuum to facilitate the removal of the diffused methane gas. This bleeding process begins approximately six months prior to the proposed mining of the coalseam 2.

It has been found that in certain coal mines, the bleeding of the methane gas also lowers the moisture content of the coal, and therefore creates problems with coal dust which is hazardous to the coal miners carrying out the mining process. It has been found that it is desirable that water be infused back into the coal seam 2 prior to the mining process. The water infusion is commenced approximately two weeks or longer before the commencement of mining.

When the water infusion of the coal seam 2 is to be started, an apparatus 10 of a preferred embodiment is used to seal the bleed holes 4 and to infuse water into the coalseam 2 as required.

The apparatus 10 as illustrated in Fig. 2, includes a PVC pipe 11. The pipe 11 is of a length that it corresponds to the length of HRW/1158c I:he bleed holes 4 (which have a typical length of 200 The pipp II is therefore a lengthwise connection of a number of individual pipes.

The pipe 11 has an internal diameter of 16 mm which is substantially smaller in diameter than the 85 mm internal diameter of the bleed holes 4.

As illustrated in Fig. 2, the pipe 11 has an aperture or inlet hole 12 on the curved outside surface of the pipe 11. In a preferred embodiment, the inlet hole 12 has a substantially conventional non return valve (not illustrated) to maintain pressure in the bag 13 if water is turned off. Surrounding the inlet hole 12 is a water impervious bag 13 which is clamped at both its ends to the outside surface of the pipe 11 by clamps 15. The bag 13 includes an outer container bag 16 which abuts against the inside surface of the bleed hole 4 and an inner tube 14 preferably made from a rubber composite material. The inner tube 14 ensures that water does not pass out of the bag 13 and the outer bag 16 prevents damage to the inner tube 14.

The apparatus 10 is used by pumping water through the pipe 11, thus filling the bag 13 with water until a predetermined pressure is obtained whereby the bag 13 is expanded until it blocks the bleed hole 4.

At least one of the bags 13 is positioned at both ends of the "o bleed hole 4 to prevent water from escaping from the bleed hole 4. It has been found that water is infused back into the coalseam 2 most efficiently where blockages to the water's path are encountered.

Therefore if a number of bags 13 are positioned along the length of the bleed holes 4, and therefore a number of blockages are provided, water infusion is enhanced. To assist in the provision of water being located at various positions along the length of the bleed holes 4, a second embodiment of the apparatus is provided.

The connecting pipe as illustrated in Fig. 3 includes a water relief valve 20 which is connected to a connecting piece 21 of the pipe 11. The connecting piece 21 receives at one end 22 part of the pipe 11 while at its other end 23 another part of the pipe 11 is received in one branch 24 of a bifurcated tube 25. The relief valve 20 is received into the other branch 26 of the bifurcated tube 25. The bag 13 is clamped onto the pipe 11 and the relief valve 20 allows water which is in the pipe 11 to pass therethrough after a predetermined pressure HRN/ 1158c within the pipe 11 is reached. The water escaping through the water relief valve 20 fills the bleed hole 4 between adjacent bags 13. In this way bodies of pressurized water are located along the length of the bleed hole 4 and therefore water infusion is enhanced. Hater infusion can be further enhanced if a wetting agent is added to the water.

The foregoing describes only some embodiments of the present invention, and modifications obvious to those skilled in the art can be made thereto without departing from the scope of the present invention.

e* e 3 *ee HRW/ 158c

Claims (9)

1. An apparatus for water infusion in coalseams, said apparatus comprising a pipe for insertion into a hole in said coalseam with a substantially annular space located between said pipe and the .su-r--a of said hole, and said pipe having at least one water N impervious bag surrounding a corresponding aperture in said pipe, said bag being sealingly clamped to said pipe and being in fluid communication with said pipe via said aperture.

2. The apparatus according to claim 1, wherein said pipe further includes at least one relief valve means connected thereto to release water from said pipe into said hole when the water pressure within said bag reaches a predetermined level.

3. The apparatus according to claim 2, wherein said relief valve means is connected to said pipe via a connecting piece which connects two lengths of said pipe, said connecting piece having a bifurcated tube, one branch of which receives said relief valve means with the other branch receiving one of the two lengths of said pipe.

4. The apparatus according to any one of the preceding claims, wherein said water impervious bag(s) includes an outer container bag and an inner tube.

The apparatus according to any one of the preceding claims, wherein said aperture further includes a non-return valve.

6. A method of water infusion in coalseams, said method comprising the 20 steps of inserting into at least one hole in said coalseam a pipe to thereby create a substantially annular space located between said pipe and the -suwoa of said hole, said pipe having at least one water impervious bag surounding a corresponding aperture in said pipe, said bag being sealingly clamped to said pipe and being in fluid communication with said pipe via said aperture; filling said bag with water via said pipe to a 25 predetermined pressure whereby said bag expands to abut against the surface of said hole thereby substantially blocking said hole; and filling the hole with pressurised water on at least one side of said bag whereby said bag blocks the passage of said water in said hole, said water being infused under pressure into said coalseam at the blockage and along the length of the hole.

7. The method according to claim 6, wherein said step of filling the hole with pressurised water includes connecting at least one relief valve means to said pipe to release said water from said pipe when the water pressure within the bag reaches a predetermined level.

8. The method according to claims 6 or 7, wherein a wetting agent is added to said water.

9. Anaratus for water infusion in coalseams, said apparatus being substantially scribed with reference to Figs. and 2 orFig. 3 the accompanying Sdrawings. [N:\libcc]00181 :HRW A method or water ifusion in coalseamns, said method being substantially as described with reference to-PIgs nd 2,-o1-ig.3 cf-the accompanying drawings. DATED this Sixteenth Day of June 1994 Christine Margaret Thompson Patent Attorneys for the Applicant SPRUSON FERGUSON N C lqparuatur for and Metlhod1 of Water In he;ion ill Coa a;llm: ABSTRACT A method and apparatus (10) for water infusion in coalseams is disclosed. The apparatus (10) includes a pipe (11) having a length that corresponds to the length of a number of bleedholes which have been drilled into the coalseam to bleed any diffused methane gas. The pipe (11) is therefore a lengthwise connection of a number of individual pipes, and an annular space is provided between the pipe (11) and the internal surface of the bleedhole The pipe (11) has at least one water impervious bag (13) surrounding a corresponding aperture (12) in the pipe. The bag (13) is sealingly clamped to the pipe (11) and is in fluid communication with the pipe (11) via the aperture and is used to block the bleedhole after the bag (13) has expanded by the ingress of water to abut against the bleedhole The bleedhole is then filled with pressurised water which is infused under pressure into coalseam Fig. 2. ro S S •4