WO1998041811A1

WO1998041811A1 - Device to facilitate the placing of slurries in up-holes

Info

Publication number: WO1998041811A1
Application number: PCT/AU1998/000169
Authority: WO
Inventors: Richard G. Dixon; Edwin Herbert Baker
Original assignee: Silverport Pty Ltd
Current assignee: Silverport Pty Ltd
Priority date: 1997-03-14
Filing date: 1998-03-13
Publication date: 1998-09-24
Anticipated expiration: 1999-09-14

Abstract

The device is in the form of a plug (11) adapted to be inserted into the lower end of an up-hole (H), at least a portion of the outer wall of the plug (11) being tapered inwardly and having an O-ring (12) slidably mounted thereon. A passage (13) through the plug (11) has a valve (15) which permits the slurry to be pumped into the up-hole (H) to fill it from the bottom to the top. The O-ring (12) may have varying configurations to form an effective seal against the wall of the up-hole (H). The plug (11) may be demountably coupled to one end of a positioning tube (17) for insertion into the hole (H). Means (41) may be mounted on the positioning tube (17) or the plug (11) for adjusting the position of the O-ring (12).

Description

DEVICE TO FACILITATE THE PLACING OF SLURRIES

IN UP-HOLES

This invention relates to devices to facilitate the placing of slurries in up - holes. It is particularly applicable to the placing of explosive slurries into up- holes in underground mines. PRIOR ART

In mining operations the placing in up holes of an explosive slurry is difficult because one has to overcome the effects of gravity. It has been a general practice to use thick gel like mixtures, in which the solid particles are shaped to ensure that it packs firmly in the hole when injected into the hole under pressure, the hole being filled from the top to the bottom. Such procedure has the disadvantage that there is a tendency for the slurry to slump where the hole passes through a band of clay or similar material and result in decoupling of the charge. Another method involving filling the hole from top to bottom is to place the charge in a sausage like bag and pack the bags into the hole one after the other. These also have a tendency to slip. Another device to facilitate the placing of slurries in up - holes from bottom to the top comprises a closure plate provided with a peripheral skirt the lower end of the skirt being flared outwardly and terminating in a sharp edge and being divided into a plurality of flexible fingers by slots extending inwardly from the edge, the plate being provided with an opening fitted with a one way valve. Means are provided for detachably coupling the plug to the upper end of a positioning tube, the lower end of which is provided with means for connecting to the outlet end of a pump discharge line. The plate is also provided with small openings through which an air bleeder tube and the firing line are threaded. As the wall of the up - hole can vary in diameter (due to drill bit wear or drill wandering) and roughness it is difficult to ensure that the plate properly engages the wall. Also there is a tendency for the fingers to be damaged and rendered unfit for use during transport and storage. THE INVENTION

It is an object of the present invention to provide a device which is more effective than presently available systems, and assists with the placing of slurries in up-holes. Having the above object in mind, the present invention provides in one aspect a plug device having a first passage therethrough and a valve means to control the flow of fluid through said first passage, and at least a portion of the outer wall of said plug tapering inwardly towards one end of said plug to form a tapered portion, said plug further including a locking means slidably mounted on said tapered portion.

The plug device of the present invention enables fluid to pass through the passage. This fluid may include, explosive slurry, concrete and/or water.

In its main application, the present invention provides a substantially more effective device for placing the slurry from the bottom to the top of an up- hole by using a cylindrical plug, with at least a portion of the outer face of the plug being tapered inwardly and downwardly and the seal between the lower end of the plug and the wall of the hole is provided by an O-ring.

Thus the present invention provides a device to facilitate the placing of slurries in up - holes including a substantially cylindrical plug having a passage therethrough, said passage being open at each end and at least a portion of the outer wall tapering inwardly towards one end, an O-ring slidably mounted on the tapered portion a one way valve positioned at or adjacent one end of said passage, said plug having means for detachable coupling said plug to one end of a positioning tube with the passage in alignment with the tube. Means may be mounted on the plug or the positioning tube for adjusting the position of the O - ring on the tapered portion.

The O - ring may be of any suitable cross section to ensure a substantially leak proof seal with the wall of the up - hole. A more effective seal is obtained when the outer face of the O - ring is corrugated or the O - ring is saw toothed in configuration. The outer portion of the O - ring, i.e. the portion adjacent the wall of the up-hole, may also be more flexible than the inner portion. DRAWINGS

The invention will be better understood by reference to the following description when read in conjunction with the accompanying drawings wherein:- Fig. 1 is a sectional view showing the initial positioning of the plug in an up-hole;

Fig. 2 is a sectional view showing the position of the plug during the pumping of the charge of slurry into the up-hole;

Fig. 3 is a sectional view showing the up-hole with the charge in position prior to firing;

Fig. 4 is a half sectional view on an enlarged scale showing the plug fitted to the positioning tube;

Fig. 5 shows a number of alternative cross sections of the O - ring;

Fig. 6 is a sectional view showing the replacement of the flap valve with a ball valve.

Fig. 7 is a sectional view showing the placement of the O - ring by pneumatic or hydraulic means.

Figure 8 is a sectional view showing the replacement of the flap valve with a piston valve. Figure 9 is a sectional view showing the replacement of the flap valve with a pressure extrusion valve.

Figure 10 is a sectional view showing replacement of the flap valve with a taper seat.

Figure 11 shows sectional views of the plug and positioning means. DESCRIPTION

Referring now to Figure 3, the essential features of the present invention can be seen in the plug 11 as shown. Figure 3 shows the condition of the plug following insertion of the slurry through the passage 13. As can be seen the plug 11 , features an upper portion 11a which is of slightly lesser diameter than the up-hole H in which the plug 11 is placed. The plug has a lower portion 11 b which tapers downwardly and inwardly. The angle of this taper can be adapted to the application in mind. Ideally, the lower portion will taper at an angle of between 5° and 25°. Although, it has been found, that for test drilling carried out to date, that the optimal angle of the taper to efficiently transfer the down loaded pressure applied by the weight of the product above the plug into the locking means or O - ring which is compressed into the wall of the blast hole, would be between 8° and 10°.

The plug will also have a passage 13 passing therethrough to enable a fluid or any type of slurry to be pumped through as necessary. A valve 15 may be placed at one end of the passage, or alternatively, at any other location throughout the passage, to enable the fluid to be pumped above the plug. When pumping of the fluid ceases, the weight of the slurry above the valve forces the valve to close thereby maintaining the slurry in position. In use, the plug is inserted up the up-hole to its desired location. The locking means, which ideally is an O - ring, is then forced up the tapered portion to engage both the plug and the walls of the up-hole. The use of the O - ring, or other locking means, in the present invention enables the plug to accommodate diameter variances of the blast hole, or up-holes. The ability of the locking means to form a flexible seal enables the plug to conform to the profile of the up-hole. That is, even if the hole diameter varies due to various factors, the present invention will still enable slurry to be filled from the bottom to the top of the hole. Ideally some form of application means will enable the plug to be placed, and locked into position, prior to filling with slurry. As can be seen in Figure 11 , the adjusting means can take the form of a cup shaped flange 41 adapted to bear on the O - ring 34. When the plug 33 is in position, the piston 42 is forced upwards, thereby pushing the flange 41 into the O - ring 34. The O - ring is then forced upwardly to engage both the up-hole H wall and the plug 33. Various adaptments to the adjustment means will be appreciated by the person skilled in the art. For example the cup shape flange may form part of the piston per se, or alternatively an outer sleeve may surround the adjustment means.

As shown in Figs. 1 to 4 the plug 11 can be moulded from a suitable plastic material such as polypropylene or high impact polystyrene, the upper portion 1 1 a ideally being substantially cylindrical and having an external diameter approximately that of the up-hole H in which it is to be used. The lower portion 11b tapers inwardly and downwardly and has a locking means, or ideally an O - ring 12, slidably mounted thereon. A cylindrical passage 13 extends from one end of the plug to the other end, the upper end being provided with a series of inwardly projecting lugs 14. A flap valve 15 to close the passage 13 is secured to the upper end of the plug by screws 16 or any other suitable means. The plug is mounted on the upper end of a positioning tube 17 by passing the lugs 14 through slots leading to a groove 18 on the outer face of the wall of the positioning tube and rotating the plug with respect to the tube so that the lugs engage under the upper wall of the groove. A cup shaped adjusting member 19 having an internally threaded hole in the base is mounted on an externally threaded portion 20 of the tube 17 so that the wall 19a of the adjusting member 19 projects into the space between the tapered portion 11b of the plug and the wall of the up-hole H to bear against the O - ring.

Alternatively, the cup shaped flange may be moved pneumatically, or hydraulically. As shown in Fig. 7 a cup shaped flange 31 is slidably mounted on the upper end of a positioning rod 32 so that when the rod is coupled to the plug 33 the flange embraces the lower end of the plug and the upper end of the flange is closely adjacent to the O - ring 34. The lower portion of the flange engages the positioning rod which is stepped as indicated by reference 36 to form a chamber 37 which is connected to a passage 38 through which compressed air (alternatively hydraulic fluid or slurry) is fed to the chamber. Sealing rings 39 and 40 are fitted above and below the chamber.

To position the O - ring compressed air is fed to the chamber 37 which causes the flange to move upwardly until the O - ring reaches the desired position.

In use a suitable detonator connected to a lead such as a Nonel detonator tube and an air bleed tube (represented in the drawings by a single line 22) is positioned in the up-hole against the wall thereof. The plug mounted on the positioning tube is inserted into the up-hole H, the position of the O - ring being adjusted if necessary, to be friction fit in the hole. As the plug moves upwardly any tendency for the O - ring to move downwardly is resisted by the adjusting means. When the desired location is reached downward force on the positioning tube causes the O - ring to slide up the plug, expand and wedge between the wall of the up-hole and the plug to lock the plug in position. The required amount of slurry is pumped into the hole through the positioning tube 17, the passage 13, and flap valve 15, into the space in the up-hole the air in the hole being displaced by the slurry passing out through the air bleed tube. The positioning tube is disengaged from the plug and withdrawn leaving the charge ready for firing as shown in Fig. 3.

In some situations an O - ring of a cross section different to the conventional circular cross section such as square (see reference 23 in Fig. 5) or D-shaped (see reference 24 in Fig. 5) may be used, as to may oval, star or triangular shaped O-rings be used depending on the application. Further, the outer face of the O - ring may be provided with a series of corrugations 25 as shown in Fig 5 or it may be provided with saw tooth projections 26 as is also shown in Fig. 5. The O - ring may be of varying flexibility across the cross section, the outer periphery being more flexible to take up variations in the wall of the hole H and seal around the air bleed tube and the firing line. The more rigid inner portion holds the O - ring in place on the tapered portion of the plug.

In the embodiment shown in Fig. 6 the flap valve is replaced by a ball valve 27 in which the ball 28 is retained by a series of upwardly projecting fingers 29 the outer ends of which are curved inwardly to form a cage.

Alternatively, as can be seen in Fig 8, the flap valve may be replaced by a piston valve 30 in which the piston 31 is retained by an upper flange 32. In use fluid passing through the passage 17 forces the piston 31 up, thereby opening a path for the fluid to pass. Once pumping of the fluid is completed, the piston returns to the start or lower position, thereby blocking fluid from returning back down the hole.

Referring now to Figure 9, the flap valve can be replaced by a pressure operated extruder valve 33 in which the outer ends are curved inwardly to form a seal 34 and only under upward pressure will the fingers open to allow passage of fluid.

Further, as shown in Fig. 10, the flap valve may be replaced by a tapered seat valve 35 in which the piston 36 is retained by a pin 37. It will be understood that the valve means need not be located at the upper end of the passage, but could be located at the bottom or at any other part of the passage.

The benefits of the present invention in placing or explosive slurries in up-holes may be summarised as follows:-

(a) charging of the blast hole from the bottom means that a column explosive product fills the blast hole;

(b) the possibility of product slumping which occurs when the slurry is loaded from the top down is eliminated; (c) the plug can be removed from the blast hole at any time;

(d) the loading procedure is the same irrespective of whether the blast hole is wet or dry;

(e) the lock up of the plug can be proven before pumping the slurry; and (f) variances in the designated hole size are easily accommodated with the flexibility of the O - ring and the ability to use various sizes of O - ring and O - ring of different cross sections.

The present invention was specifically developed to assist in the placing of explosive slurries in up-holes, however it has been found to have applications in other areas of mining. For example, when drilling underground, bodies of water are sometimes found. The head pressure of such water bodies can be great, and water or fluid can be forced through the drill hole at great velocity. In order to seal uncontrolled ground water encountered while drilling holes, whether under high pressure or not, present methods involve the use of a Van Ruth Plug. The present invention provides a suitable replacement to the Van Ruth Plug, which enable the water to be blocked or pumped to a desired location.

Alternatively, the present invention can be used to facilitate the placing of concrete or chemical grouting into drilled up-holes, for example, Cable Bolting is a method currently in use to support ground which is fractured or laminated and could potentially collapse. Cable bolting requires cables, which have been pre- tensioned or post-tensioned, to be fixed into place with concrete slurry. The present invention could be used to place pre-tensioned cable up into the hole and concrete slurry could then by pumped up through the passage in the plug device to fix the cables in the drilled up-hole. Accordingly, the present invention also enables a more efficient and cleaner cable bolting installation procedure.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A plug device having a first passage therethrough and a valve means to control the flow of fluid through said first passage, and at least a portion of the outer wall of said plug tapering inwardly towards one end of said plug to form a tapered portion, said plug further including a locking means slidably mounted on said tapered portion.

2. A plug device as claimed in claim 1 , further including means for detachably coupling said plug to a positioning tube.

3. A plug device as claimed in claim 2 wherein said positioning tube includes a second passage therethrough in alignment with said first passage.

4. A plug device as claimed in claim 1 , 2 or 3 wherein said locking means is an O-ring.

5. A plug device as claimed in any preceding claim wherein said valve means is located at or adjacent one end of said first passage.

6. A plug device as claimed in any preceding claim wherein said valve means is a one way valve.

7. A plug device as claimed in any preceding claim wherein the plug is substantially cylindrical.

8. A device to facilitate the placing of slurries in up-holes including a substantially cylindrical plug having a passage therethrough, said passage being open at each end and at least a portion of the outer wall tapering inwardly towards one end, an O - ring slidably mounted on the tapered portion, a one way valve positioned at or adjacent one end of said passage, said plug having means for detachably coupling said plug to one end of a positioning tube with the passage in alignment with the tube.

9. A device as claimed in any preceding claim wherein the valve is a flap valve.

10. A device as claimed in any one of claims 1 to 8 wherein the valve is a ball valve, extrusion valve, taper seat valve or piston valve.

11 A device as claimed in any one of claims 4 to 10 wherein means for adjusting the position of the O - ring is mounted on the plug or the positioning tube.

12. A device as claimed in claim 11 wherein the adjusting means includes a threaded cup shaped flange screwed onto an externally threaded portion of the positioning tube with the upper end of the flange bearing on the O - ring.

13. A device as claimed in claim 11 wherein the adjusting means includes a cup shaped flange slidably mounted on the positioning tube with the upper end of the flange bearing on the O - ring, and the lower end of the flange engaging the positioning tube to form a chamber, the chamber being in fluid communication with a pneumatic hydraulic source.

14. A device as claimed in any one of claims 4 to 13 wherein the O - ring is square, oval, triangular or D-shaped in cross section.

15. A device as claimed in any one of claims 4 to 14 wherein the outer face of the O - ring is corrugated.

16. A device as claimed in any one of claims 4 to 14 wherein the O - ring is saw toothed in cross section.

17. A device as claimed in any one of claims 4 to 16 wherein the compressibility of the O - ring increases across the cross section from the inside to the outside.

18. A device to facilitate the placing of slurries in up-holes substantially as herein described and shown in Figs. 1 , 2, 3 and 4 of the accompanying drawings.

19. A device to facilitate the placing of slurries in up-holes substantially as herein described and shown in Fig. 6 of the accompanying drawings.

20. A device to facilitate the placing of slurries in up-holes substantially as herein described and shown in Fig. 7, 8, 9, 10 or 11 of the accompanying drawings.