Field of the Invention The present invention relates to a protector for a detonator lead. Background

In mining operations blasting of rock is a common way of gaining access to the material being mined, such as an ore body. Typically a number of blast holes are drilled in the earth. Each blast hole is filled with explosives. Detonation of the explosives is initiated by a detonator. Generally the explosives only fill some of the blast hole, with a top portion of the blast hole, above the explosives, being filled with stemming. The detonator is activated by a detonator lead transferring a blast initiation signal to the detonator. Common detonator leads are electrical wires and 'nonel' shock tubes.

Both types of detonator leads experience problems during stemming, whereby material used in the stemming can damage or cut the leads. This causes misfiring of the explosives, which in turn costs the mine operator a substantial amount of money and is inconvenient.

The detonator leads are usually sheathed in a protective material. However protective material currently used is not sufficient to stop stemming material from damaging or cutting through the protective sheath and thus the detonator lead inside.

Depending on the circumstances the length of the stemming may be, for example, 3 to 6 m in length. Since this length is not consistent, conventional thinking is that it is impractical and/or uneconomical to provide additional protection to the detonator leads.

The present invention seeks to overcome the above-mentioned damage caused to detonator leads.

Any reference to prior art documents is not an admission that they form part of the common general knowledge of a skilled person in any jurisdiction. In this specification the terms "having", "comprising" or "comprises" are used inclusively, and not exclusively or exhaustively.

Summary of the Invention

According to the present invention there is provided a detonator lead protector comprising:

an applicator and an in-situ sheath; wherein the applicator houses the sheath and in use applies the sheath to the detonator lead within a blast hole.

In an embodiment the applicator is arranged to apply the sheath material over the detonator lead as the applicator moves along a portion of the length of the blast hole, such as during the process of loading explosives or after the explosives are loaded, but before stemming, or during the process of adding stemming in the blast hole.

In an embodiment the applicator is generally conical in shape and comprises a hole within an inner portion of the cone shape, through which the detonator lead is able to move. In an embodiment the applicator comprises a slot extending from the hole to an edge of the applicator, wherein an innermost portion of the slot comprises an interference projection for allowing the detonator lead to enter the hole and for retaining the detonator lead in the hole. In an embodiment the applicator comprises a device or means for providing the sheath material in an open state to allow the sheath to be applied to the detonator lead and a device or means for providing the sheath material in a closed state, thereby protecting the detonator lead. In an embodiment the sheath material is provided in a contracted state on a downward side of the applicator and the sheath is configured to transition to an expanded, elongate state on an upper side of the applicator.

In an embodiment the sheath is in the form of a overlapping curled material in cross section. In an embodiment during application, as the sheath moves though the applicator, a portion of the sheath is uncurled by the applicator to be open so as to allow the detonator lead to be inserted inside the sheath and then the portion is closed back to its overlapping state so as to cover and protect the detonator lead.

In an embodiment the sheath is in the form of one or more pieces of adhesive tape that are attached to the detonator lead by the applicator so as to protect the detonator lead as the sheath moves through the applicator.

In an embodiment the sheath is in the form of a shirred casing that is applied along the portion of the length of the detonator lead as the applicator moves further into the blast hole.

In an embodiment the shirred casing is filled with an expanding foam so as to create a protective layer around the detonator lead within the sheath. According to the present invention there is provided a detonator lead protector comprising:

an applicator and a sheath; the applicator comprising a first aperture therethrough, whereby the detonator lead is able to pass through the first aperture; the applicator also comprising a second aperture therethrough, whereby the sheath is able to pass through the second aperture such that the sheath is applied to the detonator lead when the detonator lead and the sheath pass through the applicator.

In an embodiment the applicator is configured to form a separation between explosives and stemming when positioned in use within a blast hole.

According to the present invention there is provided a separator for separating explosives and stemming comprising:

a barrier having a hole therethrough through which a detonator lead is able to be inserted such that the barrier can run down the detonator lead to be placed in-situ on explosives inside of a blast hole; and on top of which stemming can be deposited, such that the barrier forms a separation between the explosives and the stemming inside of the blast hole.

According to the present invention there is provided a method of applying a sheath to a detonator lead, said method comprising providing an applicator; passing the sheath through a first aperture in the applicator; passing the detonator lead through a second aperture in the applicator; moving the applicator relative to the sheath and the detonator lead, whereby the sheath material is applied to the detonator lead.

According to another aspect of the present invention there is provided a method of applying a separator between explosives and stemming in a blast hole, said method comprising providing an applicator; passing a sheath through a first aperture in the applicator; passing a detonator lead through a second aperture in the applicator; moving the applicator relative to the sheath and the detonator lead down the blast hole so that it rests on the explosives and provides a barrier between the explosives and stemming when stemming is inserted into the blast hole.

Brief Description of the Drawings

In order to provide a better understanding of the present invention, example embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figures 1 A, 1 B and 1 C are schematic representations of a blast hole in which is positioned a detonator lead according to an embodiment of the present invention;

Figure 2 is a side elevation of an applicator of a detonator lead protector according to an embodiment of the present invention;

Figure 3 is an underside view of the applicator of Figure 2 and a durable sheath material according to an embodiment of the present invention;

Figure 3A is an enlarged cross-sectional view of the sheath material of Figure 3;

Figure 4 is a plan view of the applicator of Figure 2;

Figure 4A is an enlarged plan view of a portion of Figure 4;

Figure 5 is a side elevation of an alternative embodiment of an applicator of a detonator lead protector according to an embodiment of the present invention;

Figure 6 is an underside view of the applicator of Figure 5 and a durable sheath material according to another embodiment of the present invention;

Figure 6A is an enlarged cross-sectional view of the sheath material of Figure 6;

Figure 7 is a plan view of the applicator of Figure 5;

Figure 7A is an enlarged plan view of the portion of Figure 7; and

Figure 8 is a side elevation of an applicator of a detonator lead protector according to another embodiment of the present invention;

Figure 8A is an enlarged plan view of the portion of Figure 8; and

Figure 9 is a side elevation of the applicator of Figure 8;

Figure 10 is an upper perspective view of the applicator of Figure 8; Figure 1 1 is a bottom plan view of the applicator of Figure 8 and a durable sheath material according to another embodiment of the present invention;

Figure 1 1 A is an enlarged cross-sectional view of the sheath material of Figure 11. Description of Embodiments of the Invention

Referring to Figure 1A, there is shown a body of earth 10 into which a blast hole 15 has been drilled. A detonator 23 has been placed in the blast hole 15. The detonator 23 is operatively connected to a detonator lead 12, which extends through the blast hole 15. A portion of the detonator lead 12 is wound onto a spool 24. The detonator lead 12 may be an electrical detonator lead comprising wires for carrying an electrical current to the detonator 23. Alternatively the detonator lead 12 may be a non-electric detonator lead, such as a shock tube. The portion of the detonator lead 12 wound onto the spool 24 may be further unwound so that the detonator lead 12 can be connected to a firing initiation device (not shown) at a sufficient distance from the blast hole 15.

The detonator lead 12 is provided with a detonator lead protector 100 as will be described in further detail below. The detonator lead protector 100 comprises an applicator 102 and a durable sheath 105. The durable sheath 105 provides additional protection to the detonator lead 12, that is, additional to any protection the detonator lead 12 already has. The applicator 102 applies the sheath 105 to the detonator lead 12 such that it is deployed along the portion of the length of the detonator lead 12 that will be subjected to stemming. Figure 1 B shows an explosives carrying vehicle 13 dispensing flowable explosives 21 , via a nozzle or auger 19, into the blast hole 15. The explosives 21 are shown partly filling the blast hole 15 including covering the detonator 23, such that when the detonator 23 is activated, it will cause the explosives 21 to explode. The explosives 21 are shown physically interacting with the applicator 102 and the sheath 105, such that the flow of the explosives 21 urges the applicator 102 to move down the length of the blast hole 15. The applicator 102 can also apply the sheath 105 to the lead 12 after the explosives have been added by putting stemming or drill cuttings into the applicator to weigh it down. The applicator 102 will travel down until it contacts the explosives. In an embodiment the applicator 102 may act as a barrier between stemming 20 and the explosives 21 . As the applicator 102 moves down the length of the blast hole 15, the sheath 105 is caused to extend over at least a portion of the detonator lead 12 extending substantially from the spool 24 to the applicator 102. In particular this portion coincides with a portion of the blast hole 15 in which the stemming will be positioned (as seen in Figure 1 C).

Figure 1 C shows the applicator 102 positioned above the explosives 21. The applicator 102 is generally positioned at an uppermost portion of the explosives 21 . Also shown is stemming 20 filling the remainder of the blast hole 15, above the explosives 21. That is, the stemming 20 is located on the applicator 102 such that the applicator 102 at least partially acts as a barrier between the stemming 20 and the explosives 21. In this way the applicator 102 at least partially prevents material from the stemming 20 penetrating into the explosives 21 , which can otherwise cause the explosives to deflagrate rather than detonate.

Further, due to the extension of the sheath 105 between the applicator 102 and the spool 24 over the detonator lead 12, the detonator lead 12 is protected from the material forming the stemming 20 as the stemming 20 is placed within the blast hole 15.

Referring to Figures 2 to 4A, an embodiment of an applicator 102 is shown. The applicator 102 is generally conical in shape and comprises an inner top portion 120 that flattens the peak of the cone shape, an opposite circumferential bottom portion 122 and a side portion 124, where the side portion 124 forms a generally conical shape. The top portion 120 comprises a hole 130 generally at the peak of the cone shape, through which the detonator lead 12 is able to move. The detonator lead 12 is able to be inserted into the hole 130 through a slot 126 radially extending through side portion 124 and the top portion 120. The slot 126 comprises a neck 128, which is a narrowing of the slot 126, that acts as an interference projection that allows the detonator lead 12 to enter the hole 130 and also retains the detonator lead 12 in the hole 130. Thus the applicator 102 is able to be inserted over the detonator lead 12 in a manner that does not require threading of the detonator lead 12 through the hole 130. Further the applicator 102 is able to travel along a part of the length of the detonator lead 12. In particular the applicator is able to travel from the spool 24 down the blast hole 15.

The sheath 105 is able to be coiled 1 15 within the inside of the cone shaped wall 124. A cross-section of this embodiment of the sheath 105 is shown in Figure 3A. The sheath 105 may be formed of, for example, overlapping braided nylon. The overlap is shown as 109, with the sheath 105 having a hole 103 inside that is able to receive the detonator lead 12. The overlap 109 is formed by curling of the sheath material 105. The overlap 109 has an opening 107. The sheath 105 may be expanded so that the overlap 109 is temporarily removed thereby allowing access to the inside 103 through the opening 107. The sheath 105 is resilient such that it is biased to reinstate the overlap 109, thereby closing the opening 107, with the detonator lead 12 inserted inside of the hole 103.

Referring to Figure 4A, the top portion 120 of the applicator 102 is shown in more detail. Top portion 120 comprises an arc shaped slit 132 surrounding the opening 130. An opening in the arc shape permits passage of the slot 126 there through, along with enough of the body of the top portion 120 to provide sufficient structural resilience to the surrounding material of the hole 130 and neck 128. In use the slit 132 permits the sheath 105 to pass there through. Thus on the underside of the applicator 102, the coiled sheath material 115 can be stored within the applicator 102. A free end of the sheath 105 can be inserted through the slit 132 thereby opening the sheath 105. Then as the sheath 105 is fed through the slit 132 it will, due to its resilience, fold around the detonator lead 12 as it passes through the hole 130.

As the applicator 102 is moved along the length of the blast hole 15 the detonator lead 12 travels through the hole 130 and the coil 1 15 is unwound so that the sheath 105 travels through the slit 132, thereby surrounding and protecting the detonator lead 12.

Referring to Figures 5 to 7A, an embodiment of an applicator 102' is shown. The applicator 102' is generally bell shaped and comprises a top portion 220, an opposite bottom portion 222 and a side portion 224, where the side portion 224 forms the bell shape. The top portion 220 comprises a hole 230 at the top of the bell shape, through which the detonator lead 12 is able to move. The detonator lead 12 is able to be inserted into the hole 230 through a slot 226 radially extending through the side portion 224 and the top portion 220, without the need to thread the detonator lead 12 through the hole 230. The slot 226 comprises a neck 228, which is a narrowing of the slot 226, that acts as an interference projection that allows the detonator lead 12 into the hole 230 and also retains the detonator lead 12 in the hole 230. As the applicator 102' is able to be inserted over the detonator lead 12 it is able to travel along the part of the length of the detonator lead 12.

The sheath 105', in this embodiment comprises at least one length of adhesive tape 260 and another length of a strip of material 262. Preferably the strip of material 262 is also adhesive tape. The adhesive tape 260 is wound onto a reel 240. Strip of material 262 is wound onto a reel 242. Each of the reels 240 and 242 are secured to the inside of the wall 224 by spindles 244. As shown in Figure 6A the tape 260 cooperates with the strip of material 262 to sandwich the detonator lead 12' so as to protect it. Adhesive between the tape 260 and the strip of material 262 is indicated as 264. In this embodiment the detonator lead 12' is in the form of two insulated electrical wires. Referring to Figure 7A, the top portion 220 of the applicator 102' is shown in more detail. Top portion 220 comprises two spaced apart slits 250 on either side of the opening 230. The slits 250 are generally parallel with the slot 226 in this embodiment. In use slits 250 allow the tape 260 and the strip of material 262, respectively, to pass there through. This allows the tape 260 and the strip of material 262 on the underside of the applicator 102' to pass through the respective slits of the applicator and to be joined together on the other side of the applicator 102' to capture detonator lead 12 so as to form the sheath 105'.

As the applicator 102' is moved along the length of the blast hole 15, the detonator lead 12' travels through the hole 230 and the sheath material 105' is formed as the tape 260 and the strip of material 262 travel through the slits 250 and make contact thereby encapsulating and protecting the detonator lead 12'.

In an embodiment the sheath 105 is in the form of a shirred casing that is applied along the portion of the length of the detonator lead 12 as the applicator 102 moves further into the blast hole 15.

The shirred casing is preferably filled with an expanding foam so as to create a protective layer around the detonator lead 12 within the sheath 105.

Referring to Figures 8 to 1 1 A, an embodiment of an applicator 102" is shown. The applicator 102" is generally of an inverted frustoconical bowl shape and comprises a top edge 320 that forms the outermost circumference of the cone shape, a conically shaped side 324 and a lower edge 322 that forms an inner most circumference of the truncated cone and which also forms a lip of the inverted bowl. The bowl shaped portion has a generally flat circulate base 330 that is preferably level with the edge 320, a sidewall 328 which is generally cylindrical in shape although it may be somewhat conical, and in an embodiment frustoconical transitions 334 and 336 between the side wall 328 and the lip 332 and base 330 respectively. There is a void 340 between the edge 320 and the base 330, which is also defined by the inside 326 of the sidewall 324, the sidewall 328 and the transitions 334 and 336. The opposite side of the base 330 has a surface 360. There is a void 350 provided by the bowl portion underneath the surface 360, and defined by surface 360 and the inside surface 348 of the sidewall 328 and transitions 334 and 336.

The base 330 has a centrally disposed nipple 332 projecting upwardly from the surface of the base 330. The nipple 332 comprises a hole 130 from one side of the base to the other, through which the detonator lead 12 is able to move. The detonator lead 12 is able to be inserted into the hole 130, through a slot 126 radially extending through the side of the nipple 332, the base 330, the side wall 328 and transitions 334 and 336, and through the side wall 326 to the edge 320. The slot 126 comprises a interference projection 128', which is either a narrowing of the slot 126 or a serpentine path under the projection, that acts to interfere with the detonator lead 12 in a manner that allows it to enter the hole 130 but also retains the detonator lead 12 in the hole 130. Thus the applicator 102" is able to be inserted over the detonator lead 12 in a manner that does not require threading of the detonator lead 12 through the hole 130. Further the applicator 102" is able to travel along a part of the length of the detonator lead 12. In particular the applicator is able to travel from the spool 24 down the blast hole 15.

The sheath 105 is able to be coiled 1 15 within the inside of the void 350 of the bowl portion. The base 330 has an arc shaped slit 132 surrounding the nipple 332 and thus the opening 130. The sheath 105 of this embodiment is the same as described in the first embodiment.

In use, the slit 132 permits the sheath 105 to pass there through. Thus on the underside of the applicator 102", the coiled sheath material 1 5 can be stored within the void 350. A free end of the sheath 105 can be inserted through the slit 132 thereby opening the sheath. Then as the sheath 12 is fed through the slit 132 it will, due to its resilience, fold around the detonator lead 12 once it has passed through the hole 130.

The void 340 can receive a weight, such as stemming material or explosive or drill cutting, or other weighty material to apply enough force (due to the weight) to weigh the applicator down and move it down the hole. The applicator can act as a barrier between the explosives and the stemming. In this embodiment it is installed after the explosives have been loaded or at the end of explosives loading.

As the applicator 102" is moved along the length of the blast hole 15 the detonator lead 12 travels through the hole 130 and the coil 1 15 is unwound so that the sheath 105 travels through the slit 132, thereby being applied so as to surround and protect the detonator lead 12.

In use the detonator lead 12/12' is passed through the hole 130/130' of the applicator 102/1027102". The sheath 105/105' is arranged to pass through the slit / hole(s)

132/250 such that the sheath is applied to the detonator lead 12/12' as the detonator lead 12/12' and the sheath 105/105' pass through the applicator 102/102', due to the urging of the applicator 102/102' down the blast hole 15, due to the flow of explosives 21 or stemming 20 contacting the side 124/224.

When the applicator 102/102' is in place, the applicator 102/102' forms a separation barrier on the explosives 21 at least partly preventing the stemming 20 from penetrating into the explosives 21. It will be appreciated that the sheath need not extend the full length of the detonator lead and can be positioned to protect the detonator lead in the position at which the stemming material will be located within the blast hole. Additionally the applicator is able to form a barrier to the stemming entering the explosives. Modifications and variations as would be apparent to a skilled person are intended to fall within the scope of the present invention.