AU2001266433A1

AU2001266433A1 - Method and apparatus for providing a primer with a detonator in a borehole

Info

Publication number: AU2001266433A1
Application number: AU2001266433A
Authority: AU
Inventors: Bengt Aanonsen; Bjorn Finden
Original assignee: Dyno Nobel Asia Pacific Pty Ltd
Current assignee: Dyno Nobel Asia Pacific Pty Ltd
Priority date: 2000-07-03
Filing date: 2001-06-29
Publication date: 2002-04-11
Anticipated expiration: 2021-06-29

Description

Method and apparatus for providing a primer with a detonator in a borehole.

The invention concerns an apparatus with a primer and a detonator for insertion into a charging hose for inserting bulk explosives in a whole. A method for the ₅ use of the apparatus in connection with the charging of bulk explosives in a whole and a charging device for charging with the apparatus is also described.

When blasting rock cavities and tunnels in rock, it is common to bore holes into the rock and then to place explosives, preferably bulk explosives, into the bore- o hole along with the primer and detonator, for succeeding ignition of the explosive. The explosive, the primer and the detonator are often run into the bore hole by means of specific devices or systems designed for the purpose. The explosive can be in powder, pasta/gel, slurry or emulsion form.

s The holes may have various directions, from horizontal to vertical/upwards directed. Of mainly safety reasons it is often desired to be able to perform the charging at a certain distance from the borehole. The reason may be, that the hole is difficult to access, that the area above/in front of the hole can represent danger and that the working operation in this way can be performed faster and o safer.

Various systems for remote placement of the bulk explosives in boreholes are known. These systems comprise feeding systems for hoses or sticks with bulk explosives- and branch pipe for insertion of necessary primer with detonator. 5 The hose or the sticks usually have a diameter of between 1 cm and 15 cm usually made of a flexible material, for instance rubber or plastic. A primer with detonator may be pushed in front of the hose with bulk explosives, to the place to be charges, usually to the bottom of the borehole. The primer is often packed in a sort of cartridge, or skin, to form a "sausage like" unit the detonator is pushed o into.

Examples of prior art are shown in the Swedish publications 7506593-8 and 465 566. SE-465 566 shows a feeding device for flexible hoses or sticks and a charging unit. The feeding device comprises wheels or bands for conveying the hose or sticks and a branch pipe with feeding unit for inserting a primer with detonator.

SE 7506593-8 shows an apparatus for the insertion of a charge in a borehole. The apparatus comprises an unit with fuse/wire spooled around the apparatus.

In these publications it is shown that a primer with a detonator is carried ahead of a feeding hose and is in this way pushed into a borehole. However, it happens that in some cases and attempted charging must be disrupted - and the items must be pulled out again. This will be difficult with the apparatuses shown in the prior art. Furthermore, it can be a problem that the detonator "falls" into the borehole when this is inclined downwards or vertical. Such holes are often filled with water or other fluids, such that the primer with detonator becomes sur- rounded by water, outside the bulk explosives that are filled, and this may effect the ignition of the bulk explosive.

The above mentioned and other disadvantages relating to the charging of boreholes are omitted with the present invention. The invention concerns an appara- tus adapted to include primer with detonator intended to be provided in a borehole by means of a charging hose for the filling of explosives into the hole. The apparatus comprises a cartridge-shaped plug adapted to be pushed into the opening of the charging hose and to be releasable held in the charging hose, and to be freed or released from the charging hose when the explosives are made to flow out of the charging hose. The apparatus may have an open and a closed end, and the primer will then normally be filled through the open end, and be placed in the charging hose with the closed end first. The detonator is placed in the apparatus and the primer through the open end. Alternatively, a plug or seal in the open end with an opening for the detonator can be formed. The detonator should preferably be protected by the apparatus when this is put in place.

The cartridge-shaped plug does not necessary need to seal the outlet of the charging hose, because the volume flow and the viscosity of the bulk explosives are such that the bulk explosives will apply a sufficient force on the plug to push it out, without the plug necessarily sealing the outlet of the charging hose. The cartridge is releasably secured in the charging hose due to the friction between the tube and the cartridge, and this friction force is what is exceeded when the bulk explosives flow out of the charging hose. The bulk explosives can be pumped into the charging hose, or can flow out due to gravity.

Furthermore, the invention comprises a method for providing a primer with detonator in a hole to be blasted by means of an apparatus adapted to incorporate primer with detonator to be provided in a borehole by means of a charging hose for the filling of explosives in the hole where the primer and detonator is inserted in a cartridge shaped plug, where the plug is pushed into the outlet of the charging hose and is releasable secured in this during the insertion of the hose in the hole, and where the plug is released from the charging hose by the bulk explosives when this is lead out of the charging hose.

The invention also describes a method be using a charging device comprising a feeding unit, a branch tube with an inlet section and an outlet section connected with a deviated section, a transport channel, a guiding tube and a charging house, where the feeding unit is adapted to feed the charging hose through the guiding tube and into the outlet section of the branch pipe comprising the following steps:

Inserting the charging hose into the guiding tube by means of the feeding unit such that one end of the charging hose is placed in the guiding tube, inserting the apparatus into the transport channel, conveying the apparatus through the trans- port channel and into the branch pipe forward to a stopping device placed in the outlet section of the branch pipe, feeding the charging hose such that the charging hose is guided outside the apparatus, and releasing the stopping device such that the charging hose with the apparatus can be conveyed out of the outlet section of the branch pipe and into the bottom of the hole.

The invention also comprises a charging device for charging bulk explosives into holes, where the charging device comprises a feeding unit for feeding a charging hose, a guiding tube for guiding the charging hose, and a transport channel for inserting the apparatus into a branch pipe. The charging device furthermore comprises a stopping device holding the apparatus in an outlet section of the branch pipe until the charging hose is led to the outside of the apparatus.

The apparatus is filled with a primer and a detonator, known in the art. The ap- paratus can manually or automatically be inserted in the end of the charging hose, before this is led into a hole, usually a borehole or blasting hole in rock. Preceding the insertion of the charging hose in the hole, bulk explosives are led out of the charging hose and the bulk explosives thereby pushes the apparatus out of the charging hose, such that this stays in the borehole surrounded by bulk explosives. The bulk explosives continues to flow out of the charging hose while this is withdrawn through the hole, and the hole is filled with a predetermined amount of bulk explosives. The detonator communicates in a ordinary way by means of wire or fuse with device well known in the art for igniting the detonator.

This charging device may appear similar to the one described in the Swedish publication SE-465 566, but the device according to the present invention also comprises a stopping unit in the branch pipe (denoted as guiding tube 50 in the Swedish publication). The branch pipe comprises two substantially straight areas connected with a curvature or bend, such that the two areas form an angle in re- lation to each other. A guiding tube is connected with the branch pipe in this cur- vature such that the guiding tube forms a substantially straight extension of the one substantially straight area and an angle with the other substantially straight area. The stopping device is provided in the straight area of the branch pipe forming an extension of the guiding tube, such that the device can be "parked" against the stopping device after insertion in the branch pipe. The stopping device can be controlled in various ways, as long as it stops the apparatus until the charging hose is led over the apparatus. A counter for the charging hose can for instance be used to indicate when this is placed over the apparatus, and when the charging hose is in a position that accepts the conveying of the apparatus. This position is in an area of the guiding tube before the transition to the branch pipe. The stopping device can be controlled electrically, pneumatically or hydrau- lically. Photocells or other means can be used to sense and control this process. Short description of the drawings.

The invention is more closely described below with reference to the accompanying drawings, where: - fig. 1 shows the apparatus adapted to incorporate primer with detonator in accordance with the invention with a guiding and friction body where the walls are indicated with dashed lines to show that the apparatus is hollow, and a section of the apparatus, fig. 2 shows the apparatus of fig. 1 , with an end flange and where primer, detonator and cavity to take up the detonator is included with dashed lines, fig. 3 shows the apparatus of fig. 2 placed in a branch pipe, where the apparatus also comprises sealing rings, three guiding and friction organs and where the detonator is partly placed in the apparatus, and the cross section of the apparatus, fig. 4 shows the apparatus of fig. 3 placed in a charging device, where the apparatus is on its way from a transport channel to a stopping device, fig. 5 shows the charging device of fig. 4, where the apparatus is held against the stopping device.

Below follows an embodiment of the invention with reference to the accompanying drawings.

Fig. 1 shows the apparatus A in a simple embodiment of the invention where this may comprise a cartridge or plug 1 and a friction organ 2. Friction organ 2 may be an integrated part of the apparatus A. Alternatively the friction organ may be releasably connected to the apparatus A, such that this may be changed as needed, for instance with charging hoses with various diameters. The apparatus A can also include several friction organs 2. The fig. A-A shows a cross section of the cartridge 1. The apparatus A is preferably made of plastics, cardboard or other suitable material, and is shown with an open end and a closed end, in this case pointed. The close end could be rounded, flat or have an other shape, but it is advantage if it is given a shape that facilitates the insertion in a charging hose 21. The open end can be sealed with a plug or anything suitable with an opening for the insertion of a detonator 7. The insertion in the end of the charging hose 21 can be performed manually or automatically, which will be described later in the description. Before it is inserted in the charging hose 21, the appara- tus A is filled with a primer 3, and a detonator 7 is inserted into the primer 3. The apparatus A may be prefilled/produced with primer 3, or the primer may be filled later, for instance just before it shall be used. The detonator 7 is of safety reasons normally not inserted into the primer 3 before it shall be used. The detonator 7 and the primer 3 are well known components within this line of technology. The frictions or securing organ 2 shall ensure that cartridge 1 does not fall out of the charging hose 21 before bulk explosives are led out of the charging hose 21 and presses the apparatus A out. The friction organ 2 is shown formed as one thin fin 2, but other shapes and numbers can also be used. Fig. 3 shows three fins. The friction organs 2 should be elastic, such that they are biased towards the walls in the charging hose 21 when the apparatus A is inserted into this. The friction organs 2 may be made elastic by forming them with for instance a V- shape (not shown) and they may be dimensioned such that the apparatus A can be held in place in charging hoses 20 with a multitude of dimensions. The friction organs 2 may also be formed to comprise a guiding function. This will be of par- ticularly importance during automatic or semiautomatic charging with the charging hose 21.

Fig. 2 corresponds to fig. 1 but shows some further details. The cartridge or the plug 1 is here equipped with a solid end flange 4. This will abutt the one end edge or outlet of the charging hose 21 and prevent the apparatus A from moving to far into the charging hose 21 , and simultaneously it will protect the cartridge 1 and the charging hose 21 when they are to be inserted in the borehole. Flange 4 has also a function during automatic charging because this flange 4 will then be what stops the apparatus A against a stopping device 19. Flange 4 will in addi- tion be useful in connection with holding the apparatus during the filling of primer 3 in the cartridge 1. The figure also shows the primer 3, the detonator 7 and a protected cavity 5 with dashed lines in the apparatus A. The cavity 5 has been included to protect the detonator 7 during the insertion in a borehole. The cavity in its simplest form, may be provided by letting the cartridge 1 be dimensioned "a bit too long" such that the necessary amount of primer does not fill the cartridge 1 entirely.

Fig. 3 shows the apparatus A from the figures 1 and 2 placed in a branch pipe 9. The apparatus A is however additionally provided with the seals 8 around the circumference of the cartridge 1. The purposes of the seals 8 is to seal a cavity between the cartridge 1 and the branch pipe 9 or a transport channel 14 such that the apparatus A may be transported by means of pressurized air as with "pneumatic dispatch". This is particularly useful during automatic charging. The sealing rings 8 have an additional function in that way they also wipe away/brings along spillings of bulk explosives from the charging hose 21 within a charging device.

Fig. 4 shows a known charging device where the apparatus A as shown on fig. 3 is on its way towards a stopping device 19 in accordance with an additional feature of the invention. The charging device comprises a guiding tube 15 and a deviated branch pipe 16, 17, 18. The deviated branch pipe 16, 17, 18 has two substantially straight sections, an inlet section and an outlet section 16, 18 respectively connected with a deviated section 17 such that the two sections 16, 18 forms an angle to each other. A guiding tube 15 is connected to the deviated section 17 such that it forms an extension of the straight outlet section 18. An opening 20 is placed between the guiding tube 15 and the deviated section 17 such that the charging hose can be led through the guiding tube 15 and through the deviated and the straight outlet section of the branch pipe 17, 18.

The stopping device 19 comprises a locking pin 12 in which the apparatus A is held against and stopped and that holds the apparatus A until the charging hose is led on the outside of the apparatus A. The stopping device 19 is shown purely mechanically, in that a wheel 13 is displaced by the charging hose 21 such that the locking pin 12 releases the apparatus A and the "ready and charged" hose can be led out of the outlet section 18 of the branch pipe. However, the stopping device 19 can be controlled in other ways as long as it stops the apparatus A until the charging hose 21 is led over the apparatus A. A counter (not shown) for the charging hose 21 may for instance be used to denote when this is placed over the apparatus A and when the charging hose 21 is in a position that accepts conveying of the apparatus A. This position is in the area 10 of the guiding pipe 15 in front of the transition to the branch pipe 17, 18. Locking pin 12 may alternatively be controlled electrically, pneumatically, hydraulically or a combination for these. Photocells or other means can also be used to sense and control this process. The guiding tube 15 has preferably a reasonably small gap in relation to the charging hose 21, to prevent to much pressurized air to leak out if the apparatus A is to be conveyed to the stopping device 19 by pressurized air. A seal may of course also be provided if necessary. However, the apparatus A may be conveyed in other ways, making this uncritical. Stemming or driven rolls are examples of such methods. Reference numeral 14 shows a delivery channel for the apparatus A to the branch pipe 16, 17, 18. This results in the charging hose being charged from a substantial distance (tenths of meters) and this has important advantageous in relation to safety.

Fig. 5 corresponds to fig. 4 with the exception being, the figure for showing the apparatus A in a position placed towards the stopping device 19 before the conveying of the charging hose 21.

An example of a method according to the invention for charging boreholes with the charging device shown on fig. 5, will comprise the steps of placing a charging hose 21 in the area 10 of the guiding tube 15, inserting the apparatus A into the end (not shown) of the transport or delivery channel 14, applying pressurized air in the transport channel 14 such that the apparatus A is pushed from the end (not shown) of the transport channel 14 and completely in to the outlet end 18 of the branch pipe where it is stopped against the stopping device 19, conveying the charging hose 21 such that it goes over the apparatus A until it reaches the flange 4, releasing the stopping device 19, leading the charging hose 21 by means of a feeding unit (not shown) or in other way into a hole, where it is to be blasted, for instance a borehole for blasting tunnels or rock cavities (not shown), applying pressure by means of a pump (not shown), or another way, in bulk explosives in the charging hose 21 such that it presses the apparatus A out of the charging hose 21 , into the borehole and fills the borehole with bulk explosives in a predetermined amount, while the charging hose is withdrawn through the bore- hole. The bulk explosives displace any water or other fluids in the borehole. The charging hose 21 is then withdrawn entirely to the area 10 in the guiding tube 15, and the apparatus A is ready to "charge" the charging hose 21 anew with the a new apparatus for charging a new borehole.

The shown examples are only intended to illustrate embodiments of the invention and the invention is only delimited by the enclosed claims.

Claims

New Patent Claims:

1. An apparatus adapted to take up a primer (3) with a detonator (7) and adapted to be provided in a borehole by means of a charging hose (21) for the filling of explosives in the hole, characterized in that it comprises a cartridge shaped plug (1) adapted to be pushed into the outlet of the charging hose (21) and to releasable be held in the charging hose (21) and to be released from this when the explosives are led out of the charging hose (21) and that the cartridge shaped body (1) comprises an outside flange (4).

2. The apparatus according to claim 1 , characterized in that the apparatus (A) comprises one or several guiding and friction organs (2) situated on the outside diameter of the cartridge shaped body (1) of the apparatus (A).

3. The apparatus according to claim 1 , characterized in that the outside flange (4) is adapted to be held by the apparatus (A) in a charging device.

4. The apparatus according to claim 1 , characterized in that it comprises seals (8) for sealing between the appa- ratus (A) and a transport channel (14), such that it can be conveyed pneumatically to a position ahead of the charging hose (21).

5. The apparatus according to claim 1 , characterized in that it is formed with a length greater than what is nec- essary for placing a predetermined amount of primer, such that it protects the detonator (7) to be inserted in the apparatus (A).

6. A charging device for charging bulk explosives in holes, there the charging device comprises a feeding unit for feeding a charging hose (21), a guiding tube (15) for guiding the charging hose (21), and a transport channel (14) for inserting the apparatus (A), a branch pipe comprising of substantially straight sections, and an inlet section and an outlet section (16, 18) respectively, in connection with a deviated section (17) letting the two sections (16, 18) form an angle in relation to each other, characterized in that the charging device furthermore comprises a stopping device (19) holding the apparatus (A) in the outlet section (18) of the branch pipe until the charging hose (21) is led on the outside of the apparatus (A).

7. The charging device according to claim 4, characterized in that the stopping device (19) comprises means releasing the apparatus (A) when this is sufficiently placed in the outlet of the charging hose (21).

8. A method for providing a primer (3) with detonator (7) in a hole to be blasted by means of an apparatus adapted to take up primer (3) with detonator (7) and intended to be provided in a borehole by means of a charging hose (21) for the filling of bulk explosives in the hole, characterized in that the primer (3) and detonator (7) is inserted in a car- tridge shaped plug (1), that the plug (1) is inserted into the outlet of the charging hose (21) and is releasably secured in this during the insertion of the charging hose (21) in the hole, and that the plug (1) is released from the charging hose (21) by the bulk explosives when this is led out of the charging hose.

9. The method according to claim 8 with a charging unit comprising a feeding unit, a branch pipe with an inlet section and an outlet section (16, 18) connected with a deviated section (17), a transport channel (14), a guiding tube (15), and a charging hose (21), where the feeding unit is adapted to convey the charging hose (21) through the guiding tube (15) and into the outlet section (18) of the branch pipe, characterized in the following steps: insertion of the charging hose (21) in the guiding tube (15) with the feeding unit such that one end of the charging hose (21) is placed in the guiding tube (15), insertion of the apparatus (A) into the transport channel (14), conveying the apparatus (A) through the transport channel (14) into the branch pipe (16, 17, 18) until it reaches a stopping device (19) placed in the outlet section (18) of the branch pipe, feeding of the charging hose (21) such that the charging hose (21) is led on the outside of the apparatus (A), and releasing the stopping device (19) such that the charging hose (21) with the apparatus (A) can be led out of the outlet section (18) of the branch pipe.

10. The method according to claim 8, c h a r a c t e r i z e d in that it further comprises: feeding the charging hose (21) into a borehole to a place where a bulk explosive shall be placed; pumping the bulk explosives such that it presses the apparatus (A) out of the charging hose (21).

11. The use of the apparatus (A) in according with claim 1 in a charging hose (21) for bulk explosives.