WO2016070246A1

WO2016070246A1 - Shell

Info

Publication number: WO2016070246A1
Application number: PCT/AU2015/050693
Authority: WO
Inventors: Aaron AUSTIN; Kim HENLEY; Shaun CROSSMAN; Sylvain BRIEN; Sophie BEAULIEU; Jan BROCHOCKI
Original assignee: Orica International Pte Ltd
Current assignee: Orica International Pte Ltd
Priority date: 2014-11-05
Filing date: 2015-11-05
Publication date: 2016-05-12
Anticipated expiration: 2017-05-05

Abstract

A shell for use in blasting, the shell comprising an elongated body, the elongated body having a distal end arranged for housing an explosive material, a proximal end arranged to permit introduction of at least one detonator into an interior of the shell, and a 5 cavity for holding the at least one detonator in a location in which operation of the detonator results in explosion of the explosive material, wherein the shell includes a track for running a detonator activation lead, and a retaining formation for holding said activation lead.

Description

SHELL

Field of the Invention The invention relates to a shell for use in blasting. More specifically, the present invention relates to a shell for an explosive charge.

Background of the Invention Blasting is a common technique in mining for fracturing a substrate, such as rock, to facilitate excavation and removal. Blasting involves controlled explosions, typically using shells that contain an explosive charge that is initiated by a detonator. A detonator is a device for initiating an explosive, and may be in the form of an explosive device that has transmission wires/leads attached to initiate the explosive from a remote position on the surface. The explosive charge is primed with the detonator sitting in the explosive or explosive cavity region, with the transmission wires/leads protruding outside the shell and any attached anchoring devices up to the surface of the blasthole.

Currently available shells are designed to accommodate manufacturing, without consideration for user needs or maximal shell performance. Most available shells have a cylindrical shape making them difficult to handle, and count in cases as they are not evenly stackable. They can also roll away from the blasthole during bench set up. Priming of available shells requires multiple steps and results in the detonator hanging from the wire/lead at a skewed angle impeding progress down a blast hole. Without efficient securing of the detonator within the shell, misfires may occur. Current shell geometry includes narrow spaces that make filling difficult and result in cavities in the solidified filling. Other shells lack the dimension required to reach critical diameter of an explosive material leading to shell failure. Accordingly, it would be advantageous to provide a shell which allows detonators to be efficiently and securely enclosed and positioned in a correct location inside the shell. More specifically, it would be advantageous for there to be provided a shell which includes multiple features to make it versatile, to facilitate field deployment, and to make it robust by maximising its detonation sensitivity.

Summary of the Invention

In accordance with one aspect of the present invention, there is provided a shell for use in blasting, the shell comprising an elongated body, the elongated body having a distal end arranged for housing an explosive material, a proximal end arranged to permit introduction of at least one detonator into an interior of the shell, and a detwell for holding the at least one detonator in a location in which operation of the detonator results in explosion of the explosive material, wherein the shell includes a track for running a detonator activation lead, and a retaining formation for holding said activation lead.

The track may circulate about a central axis of the shell. The track may run substantially within a plane, the plane being perpendicular to a central longitudinal axis of the shell. In embodiments, the track may be circular.

The track may be defined by at least one guide formation about which the activation lead is wound.

The track may be adapted to receive a first portion of the activation lead, the retaining formation may be adapted to receive a second portion of the activation lead, and said second portion may be further along the activation lead from the detonator than is said first portion. The track may be recessed within the shell such that the first portion of the activation lead, when received along the track, is housed within an outer periphery of the shell.

The shell may include an insert having a fill port, and a first cover part which fits over the insert, the first cover part defining the track and the retaining formation. The shell may further include a second cover part which fits over the first cover part, the second cover part being adapted such that, when the second cover part is in place, access is provided to introduce the detonator into the cavity, to run the activation lead along the track and to engage the activation lead in the retaining formation. The second cover part may have a skirt which covers the portion of the activation lead running along the track.

In one form, the retaining formation holds the activation lead such that the activation lead exits the shell at or near the central longitudinal axis of the shell, such that the shell hangs upright when suspended from the activation lead.

The retaining formation may be arranged to hold the activation lead by securing the activation lead.

In accordance with another aspect of the invention, there is provided a shell for use in blasting, the shell comprising an elongated body, the elongated body having a distal end arranged for housing an explosive material, a proximal end arranged to permit introduction of at least one detonator into an interior of the shell, an insert having a detwell for holding the at least one detonator in a location in which operation of the detonator results in explosion of the explosive material, and a sensitizer bottle, wherein the insert includes a retaining mechanism to secure the sensitizer bottle to the insert.

The sensitizer bottle may include a bottle and a lid which forms a watertight seal of the bottle.

The lid of the sensitizing bottle may include a locking mechanism that mates with the retaining mechanism of the insert. In embodiments, a retaining mechanism that is not a detwell may be used, for example, a peg may extend from the proximal end for retaining the sensitizing bottle.

The track and retaining formation may be adapted to hold a range of detonators of different lengths in a location in which a distal end of the detonator is positioned against an end of the cavity such that operation of the detonator results in explosion of the explosive material. This may be achieved by way of the retaining formation being configured so as to lock the detonator in the correct position by holding the detonator activation lead, for different detonator lengths, with the detonator activation lead having sufficient structure (rigidity or resistance to buckling) to hold the detonator in position.

The activation lead may be in the form of an activation wire. Alternatively, the lead may be in the form of a shock-tube or a det-cord.

In accordance with another aspect of the invention, there is provided a method of locking a detonator in a shell including the steps of:

providing a shell as described above, a detonator and an activation lead; inserting the detonator into said cavity of the shell;

running the activation lead along said track; and

locking the activation lead in said retaining formation.

Brief Description of the Drawings

The invention is described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Figure la is a top perspective view of a shell for use in blasting in accordance with an example of the present invention;

Figures lb to lj show progressive steps of insertion and locking of a detonator within the shell; Figure 2 is an exploded view of the shell;

Figure 3 is an upper perspective view of an insert of the shell; Figure 4 is a lower perspective view of the insert;

Figure 5 is a top view of the insert; Figure 6 is a top view of a sensitizer bottle of the shell;

Figure 7 shows diagrammatically connection of the sensitizer bottle to the insert; Figure 8 shows the sensitizer bottle coupled to the insert;

Figure 9 shows a body of the shell; Figure 10 shows a bottom perspective view of the body;

Figure 11 shows a top view of the body;

Figure 12 shows diagrammatically introduction of the insert into the body; Figure 13 shows the insert in place in the body;

Figure 14 shows a cross-sectional view of the shell; Figure 15 shows a top view of a first cover part of the shell;

Figure 16 shows a bottom perspective view of the first cover part;

Figure 17 shows a perspective view of the first cover part prior to coupling with the body;

Figure 18 shows the first cover part in place on the body;

Figures 19a to 19d show views of a sensitizer bottle in accordance with an alternative example; and

Figures 20a and 20b show the sensitizer bottle of Figures 19a to 19d when fitted to an insert in accordance with the alternative example. Detailed Description

With reference to Figures la to 18, there is shown a shell 10 for use in blasting, the shell 10 comprising an elongated body 12 arranged for insertion and explosion in a hole, for example, for use in tunnelling, underground development, blasting, and seismic exploration operations. Advantageously, the shell 10 has a retaining track designed for an activation wire/shock tube to be wrapped around. The retaining track allows efficient filling of the shell 10, efficient locking of a detonator to the shell 10, as well as repositioning of an activation wire/shock tube in a central location such that the shell can hang vertically from the activation wire/shock tube, thereby facilitating loading of the shell down a blasthole.

More specifically, with reference to Figures la to 18, there is shown a shell 10 for use in blasting, the shell 10 comprising an elongated body 12, the elongated body 12 having a distal end 14 arranged for housing an explosive material and a proximal end 16 arranged to permit introduction of at least one detonator 18 into an interior of the shell 10. The shell 10 includes a cavity 20 for holding the at least one detonator 18 in a location in which operation of the detonator 18 results in explosion of the explosive material. The shell 10 includes a track 22 for running a detonator activation lead 24 around/along, and a retaining formation 26 for holding the activation lead 24.

Figures lb to lj show the progressive steps for insertion and locking of the detonator 18 to the shell 10. More specifically, Figure lb shows the shell 10 prior to introduction of the detonator 18. Figure lc shows the detonator 18 being introduced to the cavity 20. Figure Id shows the activation lead 24 being bent away from the cavity 20, and Figures le to li show the activation lead 24 being progressively wrapped in a clockwise direction around the track 22 of the shell 10 to the point where the activation lead 24 is held in the retaining formation 26 such that the activation lead 24 exits the shell 10 in a central location of the shell, substantially coincident with a central longitudinal axis of the shell 10. Figure lj shows the shell 10 with a cap 28 removed from the shell 10 so as to show the activation lead 24 wrapped clockwise around guide formations 30 which define the track 22. The guide formations 30 may include a rim and one or more grooves for guiding the activation lead 24.

Accordingly, the track 22 circulates about the central axis of the shell 10, facilitated by the guide formations 30 and the circular domed cap 28 which guides the activation lead 24 to be wound around the track 22 in a generally circular manner prior to being locked into the retaining formation 26. Accordingly, the track 22 runs substantially within a transverse plane, the transverse plane being perpendicular to the central longitudinal axis of the shell 10. The track 22 may be circular or alternatively, may be of a different shape defined by the guide formations 30. For example, the guide formations 30 in an alternative example may define a track 22 which is triangular, square, hexagonal or a different shape which requires that the activation lead 24 still be wound around the guide formations 30. In this way, the track 22 may be defined by one or more guide formations 30 about which the activation lead 24 is wound.

With reference to Figure lj, the track 22 is adapted to receive a first portion 32 of the activation lead 24, the retaining formation 26 is adapted to receive a second portion 34 of the activation lead 24, and the second portion 34 is further along the activation lead 24 from the detonator 18 than is the first portion 32. This is achieved by way of the activation lead 24 firstly being wrapped around the track 22, and subsequently being engaged in the retaining formation 26. Track 22 may be recessed within the shell 10 such that the first portion 32 of the activation lead 24, when received along the track 22, is housed within an outer periphery of the shell 10. For example, as shown in Figures la and li, the first portion of the activation lead 24 is hidden beneath the domed cap 28 such that the activation lead 24 is housed within the outer periphery of the shell 10 and is protected by the domed cap 28.

Figures 2 to 18 show a shell 10 in accordance with an alternative example of the present invention which is generally similar to the example shown in Figures la to lj, and like features are indicated with like reference numerals. With reference to Figure 2, the shell 10 includes an elongated body 12, an insert 36, and a first cover part 38. The shell 10 may also include a sensitizer bottle 40, depending on usage of the shell 10. Further details of the insert 36 are shown in Figures 3 to 5. In particular, the insert 36 includes a fill port 42 and one or more detwells 44. As in the example shown in Figure 4, one of the detwells 44 may be provided with a small bung 54. Alternatively, the detwell 44 may be formed as a simple blind detwell moulding. In embodiments, one or more of the detwells 44 may be in the form of a through tunnel and a protruding peripheral lip 46 may be provided to surround upper edges of the detwells 44. The insert 36 may also include one or more retaining features for attaching the sensitizer bottle 40 to the insert 36.

As shown in Figure 5, the insert 36 may include notches 56, 58 to facilitate visual alignment when assembling the insert 36 to the elongated body 12.

The insert 36 is introduced to the elongated body 12 as depicted in Figure 12, to arrive at the partly constructed shell 10 shown in Figure 13. The first cover part 38 fits over the insert 36 as shown in Figures 14, 17 and 18. The first cover part 38 defines the track 22 and the retaining formation 26. With reference to Figure la, the shell 10 may further include a second cover part in the form of the domed cap 28 which fits over the first cover part 38, the second cover part being adapted such that when the second cover part is in place, access is provided to introduce the detonator 18 into the cavity 20, to run the activation lead 24 along the track 22, and to engage the activation lead 24 in the retaining formation 26. The second cover part may have a skirt 60 which covers the portion of the activation lead 24 running along the track 22.

As can be seen in Figures la and li, the retaining formation 26 holds the activation lead 24 such that the activation lead 24 exits the shell 10 at or near the central longitudinal axis of the shell 10. Accordingly, the shell 10 hangs upright when suspended from the activation lead 24. The retaining formation 26 may be arranged to hold the activation lead 24 by pinching the activation lead 24. Specifically, as shown in Figures 15, 17 and 18, the retaining formation 26 may be in the form of a pair of opposed indentations which form a gap of a suitable size such that the activation lead 24 is able to be held in the gap by way of interference fit. Turning to Figures 9 to 11, the elongated body 12 has at least one flat side and, in the example shown, has a plurality of flat sides 62. In particular, the elongated body 12 is generally rectangular, with each of the plurality of flat sides 62 extending in a respective plane, with each of the respective planes being parallel to the central longitudinal axis of the shell 10. Advantageously, this shaping of the shell 10 results in the shell 10 being relatively easy to handle with gloves and also prevents the shell 10 from rolling away from the blasthole. As shown in Figure 10, the elongated body 12 also has a rounded end which facilitates loading of the shell 10 down a blasthole since the shell 10 will sink better.

In one embodiment, as shown in Figures 6 to 8, the sensitizer bottle 40 may be locked into position by way of elastic deformation of the insert and/or the sensitizer bottle 40. More particularly, the insert may contain a locking mechanism 70 for retention of the sensitizer bottle. In embodiments, the locking mechanism may be positioned between detwells 44 such that the detwells 44 further facilitate retention of the sensitizer bottle in the insert. In embodiments, the sensitizer bottle may include a bung 66. Alternatively, as shown in the example depicted in Figures 19 and 20, the sensitizer bottle 40 can be formed of a bottle 48 and a separable lid 50. The lid 50 may form a watertight seal for the bottle 48. In embodiments, the lid 50 may form part of the attachment mechanism of the sensitizer bottle 40 to the insert. The sensitizer bottle 40 may be configured such that if it is placed upside-down it prevents the insert 36 from assembling correctly in the elongated body 12 to draw attention to the incorrect orientation. In embodiments, the detwells 44 together form a mechanism for locking the sensitizer bottle 40 to the insert. The detwells 44 may engage with longitudinal receptacles 52 in the sensitizer bottle 40 to prevent unwanted rotation of the sensitizer bottle 40 relative to the insert. In some embodiments, the insert may include additional features for locking the sensitizer bottle 40 to the insert.

More specifically, with reference to Figures 19 and 20, the sensitizer bottle 40 includes the bottle 48 and the separable lid 50, with the lid 50 having a collar 68 which interengages with a neck 72 of the bottle 48 to form the watertight seal. As seen in the cross- sectional view of Figure 19d, when the lid 50 is fitted to the bottle 48, an inward flange 74 of the collar 68 clips over and is retained against an outward flange 76 of the neck 72 so as to form the seal from the flanges 74, 76 held together. The lid 50 may be formed of a thermoplastic polymer material to provide material properties desirable for enabling sufficient elastic deformation and resilience. With reference to Figures 20a and 20b, the insert may include a retaining feature in the form of a finger 78 and a catch 80 which operate in conjunction with the lid 50 so as to retain the sensitizer bottle 40 in position relative to the insert and detwells 44. In the example shown, the lid 50 is formed such that the collar 68 surrounds a cavity 86 which may be sized to provide a snug fit when inserted over a tip of the finger 78 as shown most clearly in Figure 20b. This snug fit may also contribute to maintaining the watertight seal by preventing inward deflection of the collar 68 while the finger 78 remains inside the cavity 86. The catch 80 may be resiliently mounted relative to a main body of the insert such that the catch 80 is able to defect outwardly to allow passage of the lid 50 while the sensitizer bottle 40 is inserted onto the finger 78, and to resiliently deflect inwardly when the lid 50 is fully inserted over the finger tip so that the catch 80 abuts against a lower rim of the collar 68 to retain the sensitizer bottle 40 on the finger 78. The bottle 48 may also be formed with an integral fill level indicator groove 84 to facilitate correct filling of the bottle 48.

Figures 15 and 16 show tunnels 82, which may be used to orientate the first cover part 38 with automated handling - such as a mechanical process. The tunnels 82 also provide a mechanical stop in the event the first cover part 38 is assembled incorrectly on the insert 36, as the tunnels 82 are configured to correspond with the detwells 44.

Turning to Figure 18, ribs 88 are provided at an upper-most end of the first cover part 38 to provide stability when the shell 10 is placed in a carton upside-down. Advantageously, this results in facilitating handling and counting of the shells 10 when controlling inventory.

In the depicted example, the shell includes plastic assembly that substantially encloses cast mix material, emulsion, or other explosive material and the base 64 of the shell is generally rounded to make its detonation more efficiently transmitted to the explosive for initiation. The cover for the body of the shell is made of three parts: the first part (the "insert") includes a detwell/tunnel assembly, consisting of a molded tunnel/detwell and a separable sensitizer bottle; the second part (the "first cover part") is a cover that clips onto the shell; and the third part is the domed cap (the "second cover part"), which includes the retaining formation. Each part of the cover performs one or more key functions. The insert includes a pour opening to reduce spills over the detwell and tunnel openings, and may further include a feature for locking the sensitizer bottle in place. Use of a sensitizer bottle can maximize detonation output pressure allowing use of less sensitive explosive materials in the body of the shell, making the shell cheaper and safer to produce. When the sensitizer bottle is made waterproof it can preserve the explosive nature of the shell under conditions of high hydrostatic pressure, experienced in field-application.

The first or second cover part has a retaining track designed for the wire/shock tube to wrap around. The shape of the track was made to allow simultaneous retention of one or more activation leads. The detwell(s) and/or through tunnel can be off-center to one side of the insert. The retaining track allows repositioning of the activation lead in the centre to allow for vertical hanging, which facilitates loading down a blasthole.

The hemispherical shape of the cap may provide protection for the activation lead wrapped around the retaining track and aids retention by keeping activation lead in the retaining track. The domed shape can also act as a guide for the user to orient and wrap the activation lead(s) during priming of the shell with a detonator, so that the detonator(s) is properly retained within the shell. Only a single insertion step is required for each detonator, followed by a simple rotating movement for the activation lead to lock the detonator inside the shell. One or more detwells and/or through tunnels can be primed with one or two detonators. In embodiments, the through tunnel can be used to prime the unit with detonating cord/shock tube. In embodiments, the insert may contain a detwell with integrated shock protection. The overall shape of the shell is rectangular with smooth edges to facilitate handling and inventorying. The rounded bottom will facilitate loading down a hole since it will sink better. The shell disclosed herein provides better handling and simpler priming than conventional shells. The track, guides, and retaining formation are simple and intuitive. The shell structure centres the activation lead, thereby reducing the risk of sticking during descent of the shell into the blasthole. The shell is substantially enclosed, not requiring a user to come into contact with explosive during handling. The shell may further include features such as a measuring strap to support the load and/or to measure depth while loading into a blasthole. The robust internal geometry of the shell minimizes the risk of misfire. The shell may also have a generally rounded bottom shape (possibly with a flattened bottom standing platform portion) that can transmit detonation to the explosive mix more efficiently. The shell can accommodate varied methods of priming, shock protection, and/or inclusion of a sensitizer, allowing use for many different purposes. The geometry of the shell allows easy filling operation with its large opening and allows melted cast mix to flow smoothly inside. This may reduce the risk of voids forming within the cast mix during manufacturing. Voids occurring during filling are difficult to detect and can significantly reduce shell sensitivity. The cover locks the detonator in the shell thus preventing dislodgement after priming. Once the detonator has been inserted, the activation lead is wrapped around the track and locked into the retaining formation. The retaining formation allows for faster priming, detonator locking, and vertical alignment of the activation cord with the shell for easy deployment in a blasthole.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A shell for use in blasting, the shell comprising an elongated body, the elongated body having a distal end arranged for housing an explosive material, a proximal end arranged to permit introduction of at least one detonator into an interior of the shell, and a detwell for holding the at least one detonator in a location in which operation of the detonator results in explosion of the explosive material, wherein the shell includes a track for running a detonator activation lead, and a retaining formation for holding said activation lead.

2. A shell as claimed in claim 1 , wherein the track circulates about a central axis of the shell.

3. A shell as claimed in claim 2, wherein the track runs substantially within a plane, the plane being perpendicular to a central longitudinal axis of the shell.

4. A shell as claimed in claim 3, wherein the track is substantially circular.

5. A shell as claimed in any one of claims 1 to 4, wherein the track is defined by at least one guide formation about which the activation lead is wound,

6. A shell as claimed in any one of claims 1 to 5, wherein the track is adapted to receive a first portion of the activation lead, the retaining formation is adapted to receive a second portion of the activation lead, and said second portion is further along the activation lead from the detonator than is said first portion.

7. A shell as claimed in claim 6, wherein the track is recessed within the shell such that the first portion of the activation lead, when received along the track, is housed within an outer periphery of the shell, A shell as claimed in any one of claims 1 to 7, wherein the shell includes an insert having a fill port, and a first cover part which fits over the insert, the first cover part defining the track and the retaining formation. 9. A shell as claimed in claim 8, wherein the shell further includes a second cover part which fits over the first cover part, the second cover part being adapted such that when the second cover part is in place access is provided to introduce the detonator into the cavity, to run the activation lead along the track and to engage the activation lead in the retaining formation.

10. A shell as claimed in claim 9, wherein the second cover part has a skirt which covers the portion of the activation lead running along the track.

11. A shell as claimed in any one of claims 1 to 10, wherein the retaining formation holds the activation lead such that the activation lead exits the shell at or near the central longitudinal axis of the shell, such that the shell hangs upright when suspended from the activation lead,

A shell as claimed in any one of claims 1 to 11, wherein the retaining formation is

arranged to hold the activation lead by pinching the activation lead.

A shell for use in blasting, the shell comprising an elongated body, the elongated body having a distal end arranged for housing an explosive material, a proximal end arranged to permit introduction of at least one detonator into an interi or of the shell, and an insert having a detweil for holding the at least one detonator in a location in which operation of the detonator results in explosion of the explosive material, and a sensitizer bottle, wherein the insert includes a retaining mechanism to secure the sensitizer bottle to the insert. 14. A shell as claimed in any one of claims 1 to 13, wherein the sensitizer bottle includes a bottle and a lid, wherein the lid forms a watertight seal on the bottle. A shell as claimed in claim 14, wherein the lid of the sensitizing bottle forms at least part of a locking mechanism that mates with the retaining mechanism of the insert. 16. A shell as claimed in any one of claims 1 to 15, wherein the elongated body has a rounded end. 17. A shell as claimed in any one of claims 1 to 12, wherein the activation lead is in the form of an activation wire,

18. A shell as claimed in any one of claims 1 to 12, wherein the activation lead is in the form of a shock tube.

19. A shell as claimed in any one of claims 1 to 12, wherein the activation lead is in the

20. A method of locking a detonator in a shell including the steps of:

providing a shell as claimed in claim 1, a detonator and an activation lead; inserting the detonator into said cavity of the shell ,

running the activation lead along said track; and

locking the activation lead in said retaining formation.

21. A shell substantially as hereinbefore described with reference to the accompanying drawings.

22. A method of locking a detonator in a shell substantially as hereinbefore described with reference to the accompanying drawings.