A BOOSTER ASSEMBLY

Abstract

A booster assembly (60) for use in a drill and blast operation comprises in co-axial alignment: (a) a booster (65) for initiating an explosion of an explosives material in a hole (90) in a pit floor (91) as part of a drill and blast operation, (b) a spool (63) and a detonation cord (66) wrapped around the spool in a storage position outside the hole and connected to the spool and to the booster, and (b) a stake (61). The spool allows the detonation cord to be unwound from the spool as the booster is moved from the storage position to an operative depth in the hole and the spool remains in the storage position. The stake is provided for locating the spool in the pit floor proximate the hole after the booster is at the operative depth in the hole.

Description

TECHNICAL FIELD

The invention relates to a booster assembly for use in drill and blast operations.

BACKGROUND

The drill and blast process used on many mining sites involves a number of operations that are carried out by mine personnel on a pit floor.

There are safety risks for the mine personnel when on a pit floor. The safety risks are compounded when mining operations are carried out in extreme conditions, such as in mines located in very hot and in very cold regions. The safety risks are also compounded when mining in and around pits where there is geothermal activity and the surface of the pit floor is hot and unstable and the pit temperature increases with depth. When mining in these pits, by way of example there can be unpredictable geysers in drilled holes, with hot water/steam being projected upwardly.

The applicant is involved in a research and development project to minimise the above-described safety risks.

As part of the project, the inventors of the subject invention have invented an initiation system vehicle for delivering a detonation device for initiating an explosion of an explosives material, such as a bulk explosive, in a hole in a pit floor as part of a drill and blast operation. The detonation device typically contains a small charge of explosive material. The detonation device is hereinafter referred to as a “booster”.

More specifically, the term “booster” as used herein is understood to refer to a detonation device typically containing a small charge of explosive material that can be located in a blast hole for the purpose of initiating an explosion of an explosive, such as a bulk explosives material, in the blast hole. In a situation where the booster contains an explosive material, the explosive material may be a charge of liquid or solid explosive of a fixed quantity that is calculated to detonate a fixed volume of explosive emulsion (or other suitable form of explosive formulation) within a primed drilled hole in a pit floor.

The inventors have also invented a booster assembly as described herein that comprises a booster and is suitable for use with the initiation system vehicle but is not exclusively limited to use with the vehicle.

The above description is not an admission of the common general knowledge in Australia and elsewhere.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods, devices, and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, a limited number of the exemplary methods, devices, and materials are described herein.

SUMMARY OF THE INVENTION

In broad terms, the invention provides a booster assembly for use in a drill and blast operation, comprising in co-axial alignment:

• • (a) a booster for initiating an explosion of an explosive material in a hole in a pit floor as part of a drill and blast operation;
  • (b) a spool and a detonation cord wrapped around the spool in a storage position outside the hole and connected to the spool and to the booster, with the spool being provided for allowing the detonation cord to be unwound from the spool as the booster is moved from the storage position to an operative depth in the hole and the spool remains in the storage position; and
  • (c) a stake for locating the spool in the pit floor proximate the hole after the booster is at the operative depth in the hole.

In more particular terms, the invention provides a booster assembly for use in a drill and blast operation comprising in co-axial alignment:

• • (a) a booster for initiating an explosion of an explosive material, such as a bulk explosive, in a hole in a pit floor as part of a drill and blast operation;
  • (b) a spool and a detonation cord wrapped around the spool in a storage position outside the hole and connected to the spool and to the booster, with the spool being provided for allowing the detonation cord to be unwound from the spool as the booster is moved from the storage position to an operative depth in the hole and the spool remains in the storage position; and
  • (c) a stake for locating the spool in the pit floor proximate the hole after the booster is at the operative depth in the hole; and
    with an end of the spool being formed to receive and locate an end of the booster such that the booster is seated on the spool when the booster assembly is in an upright orientation in the storage position before moving the booster to the operative depth in the hole.

The booster may contain a charge of an explosive for initiating the explosion of the bulk explosive in the hole in the pit floor.

The booster and the spool may have complementary formations that allow the spool to receive and locate the booster and thereby seat the booster on the spool.

The booster may be seated on the spool by being releasably coupled to the spool so that, in use, the booster is coupled to the spool in the storage position and can be moved clear of the spool as part of a process for moving the booster to the operative depth in the hole.

The booster and the spool may have complementary formations that allow the booster and the spool to be releasably coupled together by positively docking the booster on the spool and allow the booster to be released from the positive docking and moved clear of the spool as part of the process for moving the booster to the operative depth in the hole. With this arrangement, in use, the booster, spool and stake of the booster assembly may be moved together as a unit from the storage position to a position proximate the hole.

The booster may comprise a booster casing, for example for containing an explosives charge.

The booster casing may have an engagement feature, such as a collar, that facilitates engagement of the booster with a delivery assembly, for example that forms part of an initiation system vehicle, for transporting the booster assembly to a delivery position directly above the hole.

The spool may comprise a spool casing having an engagement feature, such as a collar, that facilitates engagement of the booster assembly with the delivery assembly for transporting the booster assembly to an intermediate transfer position proximate the delivery position directly above the hole. With this arrangement, in use, the delivery assembly can transport the booster to the loading position directly above the hole, with the spool and the stake remaining at the intermediate transfer position.

The delivery assembly may be any suitable assembly for transporting the booster assembly.

By way of example, the delivery assembly may be part of the initiation system vehicle that is described in a co-pending International application entitled “A mining vehicle” filed in the name of the applicant on the same day as the subject application. The purpose of the initiation system vehicle is to transport a plurality of booster assemblies on a pit floor and deliver a booster of each booster assembly in turn to an operative depth in a hole in the pit floor with an operator located in a cabin of the initiation system vehicle or operating the initiation system vehicle remotely or with the vehicle operating autonomously so that the booster can be inserted into the hole without mine personnel having to stand on the pit floor.

The spool may have a brake to control the release of the detonation cord.

The stake may be connected to the spool so that the spool and the stake are movable as a unit.

The spool and the stake may be separately formed as two components that are connected together.

The spool and the stake may be connected together so that the spool can rotate about a central axis of the stake.

The spool may include a central cavity extending axially upwardly from a lower end of the spool that receives the stake.

The stake may include an elongate shank that is received in the cavity of the spool and supported for rotation about a central axis of the shank.

The booster may have formations that allow the booster to receive and locate a pusher element of the delivery assembly for applying a downwardly-acting force to move the booster downwardly from the delivery position into the hole to the operative depth.

The booster and the pusher element may be formed so that the pusher element can be releasably coupled to the booster.

The pusher element may be releasably coupled to the booster by forming the booster with formations that allow the pusher element to be positively docked with the booster.

The formations may include a recess in an upper end of the booster that can receive the pusher element.

The initiation system vehicle that is described in the above-mentioned co-pending International application in the name of the applicant filed on the same day as the subject application comprises:

• • (a) a storage assembly for storing a plurality of the booster assemblies at a storage position;
  • (b) a loading assembly for (i) supporting a booster of one of the booster assemblies in the delivery position above a hole in a pit floor and (ii) moving the booster downwardly into the hole and inserting the booster at the operative depth in the hole; and
  • (c) a delivery assembly for transporting the booster assemblies from the storage position in the storage assembly to the loading position.

The loading assembly may comprise the pusher element for applying the downwardly acting force to move the booster into the hole to the operative depth.

The downwardly acting force may be a downward force applied via the pusher element to the booster to move the booster into the hole.

The downwardly acting force may be a consequence of the weight of the pusher element and the booster whereby the booster can move downwardly via a gravitational force pulling the booster into the hole to the operative depth.

The pusher element may be formed to (a) couple the booster and the pusher element together to support the booster while the pusher element, in use, moves the booster downwardly into the hole to the operative depth in the hole and (b) release the booster from the pusher element when the booster is at the operative depth so that the pusher element can be withdrawn from the hole.

The delivery assembly may comprise an arm that is moveable to transport the booster from the storage assembly to the loading assembly.

The arm may comprise a retaining member for example in the form of grippers that can engage and retain the booster while the arm, in use, transports the booster from the booster storage assembly to the booster delivery position.

The arm may be pivotally mounted for movement about a vertical axis for transporting the booster from the storage assembly to the loading assembly.

The storage assembly may be adapted to store a plurality of the booster assemblies.

The storage assembly may comprise a plurality of upwardly-extending storage tubes for receiving and retaining the booster or booster assembly, with one booster or booster assembly per tube.

The storage assembly may comprise a lifting assembly for lifting each booster or booster assembly upwardly to an extended position such that the booster extends at least partially from the tube,

Each storage tube may include an internal guide that can slide in the tube and is adapted to receive and support a lower end of the booster assembly in the tube.

The internal guide may be adapted to receive and support a lower end of the stake of the booster assembly in the tube.

The internal guide may include an outer surface that has a diameter that is marginally less than a diameter of an internal wall of the tube and, in use, contacts the inner wall and facilitates sliding movement of the guide in the tube.

The internal guide may include a pair of spaced apart collars that have the above-described outer surfaces that, in use, contact the inner wall and facilitate sliding movement of the guide in the tube.

The spacing between the collars may be selected so that the guide can move in a stable way within the tube.

The internal guide may include a cavity extending from an upper wall of the guide for releasably receiving and supporting the stake. With this arrangement, the stake can be lifted clear of the internal guide when the booster assembly has been lifted to a raised position in the tube.

The storage assembly may comprise a platform that is arranged to rotate about a central upright axis, with the platform supporting the tubes. Rotation of the platform moves the tubes (and the boosters in the tubes) into a loading position. The tubes are open-ended, with the lower ends aligned with openings in the platform.

Various features, aspects, and advantages of the invention will become more apparent from the following description of embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and not by way of limitation, with reference to the accompanying drawings, of which:

FIG. 1 is a schematic view of a stemmed hole with emulsion explosive in the hole and, in very schematic form, a booster assembly in accordance with the invention in the hole;

FIG. 2 is a perspective view of one embodiment of a booster assembly in accordance with the invention in an assembled configuration;

FIG. 3 is a side view of the booster assembly shown in FIG. 2;

FIG. 4 is a vertical cross-section of the booster assembly shown in FIG. 3;

FIG. 5 is a perspective view of the booster assembly shown in FIG. 2, with the booster of the assembly lifted clear of the spool and the stake of the assembly;

FIG. 6 is a vertical cross-section of the booster assembly shown in FIG. 5;

FIG. 7 is a perspective view of a second embodiment of a booster assembly in accordance with the invention in an assembled configuration;

FIG. 8 is a side view of a booster of a third embodiment of a booster assembly in accordance with the invention coupled to a pusher element of a loading assembly for supporting and inserting the booster into a hole, with the other components of the booster assembly of this embodiment being shown in FIGS. 10-13;

FIG. 9 is a sectional view of the booster and the pusher element shown in FIG. 8 illustrating the engagement mechanism therein for selectively coupling together the booster and the pusher element;

FIG. 10 is an enlarged side view of the spool and the stake of the third embodiment of the booster assembly shown in FIGS. 8 and 9;

FIG. 11 is an enlarged sectional view of the spool of the third embodiment of the booster assembly shown in FIGS. 8 and 9;

FIG. 12 is an enlarged side view of the booster of the third embodiment shown in FIGS. 8 and 9;

FIG. 13 is a sectional view of the booster shown in FIG. 12;

FIG. 14 is an enlarged side view of another, but not the only other, embodiment of a booster that can be used as a replacement for the boosters of the embodiments shown in FIGS. 2 to 13;

FIG. 15 is a sectional view of the booster of FIG. 14;

FIG. 16 is an enlarged sectional view of the booster and the pusher element shown in FIG. 9 illustrating the booster engagement mechanism therein for selectively coupling together the booster and the pusher element, with the Figure illustrating the pusher element inserted into a cavity in the booster and locating the two components together, and illustrating a compressible engagement member in a non-compressed state;

FIG. 17 is an enlarged sectional view of the booster and the pusher element shown in FIGS. 9 and 16 illustrating the pusher element and the booster coupled together due to the compressible engagement member being in a compressed state; and

FIG. 18 is an enlarged sectional view of the booster and the pusher element shown in FIGS. 9, 16 and 17 illustrating the pusher element decoupled from the booster due to the compressible engagement member being in a non-compressed state.

Embodiments of the booster assembly of the invention are now described more fully hereinafter with reference to the accompanying drawings, in which various embodiments, although not the only possible embodiments, of the invention are shown. The invention may be embodied in many different forms and should not be construed as being limited to the embodiments described below.

DETAILED DESCRIPTION OF EMBODIMENTS

The embodiments of the booster assembly of the invention are described in the context of use with embodiments of initiation system vehicle (“ISV”) of the invention of the co-pending International application mentioned above.

FIG. 1 illustrates in very schematic form a booster 65 of an embodiment of a booster assembly 60 in accordance with the invention, such as shown in FIGS. 2 to 6, and the other Figures after the initiation system vehicle (“ISV”)—not shown in the Figures but described in more detail below—has positioned the booster 65 in a drilled hole 90 in a pit floor 91 at a selected operative depth submerged in an emulsion explosive 93 in the hole 90, with the hole 90 being stemmed and a detonator cord 66 extending from the stemmed hole 90a.

As shown in FIG. 1, the drilled hole 90 is filled via the opening 94 to a depth of 9 m with an explosive emulsion 93 rated to operate in high temperature pits, such as produced by Dyna Nobel, the booster 65 is submerged in the hole 90 at the selected operative depth (which is a function of the explosive and the detonation requirements for the hole), and the upper 7 m of the hole 90 to the surface of the pit floor 91 is filled via the opening 94 with aggregate 92 or other suitable stemming material, such as an emulsion. It is noted that the drilled hole 90 may be any suitable depth and diameter.

With further reference to FIG. 1, a spool 63 (from which the detonation cord 66 has been unwound) and an attached stake 61 of the booster assembly 60 remain coupled to the booster 65 via the detonation cord 66. As described below, the stake 61 is transferred from a storage position on the ISV to the pit floor 91 and driven into the pit floor 91 in proximity to the stemmed hole 90a. Mine personnel can tie the detonation cord 66 into other cords 66 in preparation for blasting.

It is noted that the booster assembly of the invention is not confined to use with these vehicles.

With reference to FIGS. 2 to 6, one, although not the only, embodiment of the booster assembly 60 of the invention comprises the following co-axially-aligned components:

• • (a) a booster 65,
  • (b) a spool 63 and a detonation cord 66 (not shown in FIGS. 2 to 6 but shown in FIG. 1) that, prior to use, is wrapped around the spool 63 in a storage position and connected to the spool 63 and to the booster 65, and
  • (c) a stake 61 connected to the spool 63,
    with an upper end of the spool 63 (as viewed in the Figures) being formed to receive and locate a lower end of the booster 65 (as viewed in the Figures) such that the booster 65 is positively docked with the spool 63 when the booster assembly is in an upright orientation and can be released from the spool 63 and moved independently of the spool 63.

Each of the booster 65, the spool 63, and the stake 61 may be any suitable dimensions and made from any suitable materials.

As is described below, in embodiments of the invention in which the booster assembly 60 is to be used with the above-mentioned ISV and is stored in an upwardly-extending storage tube (not shown), the booster assembly 60 includes two axially-spaced apart collars 79 with outermost surfaces 83 having diameters that are selected to be marginally less than an inner diameter of the tube so that the booster assembly 60 can be snuggly stored in the tube and can slide in the tube.

As can best be seen in FIGS. 4 and 6, the booster 65 contains a large internal cavity 73 for storing a liquid explosive 81, such as Powermite Thermo™ explosive.

A base 74 of the booster 65 (see FIGS. 4-6) is a bullnose shape that in use cooperates with an engagement recess 67 extending into the spool 63 from an upper end (as viewed in the Figures) and forms a booster dock 69 in the spool 63. The connection between the recess 67 of the spool 63 and the bullnose end 74 of the booster 65 is a push fit, i.e. frictional engagement: tight enough to support and connect the spool 63 and the booster 65 but easily separated.

The spool 63 has a central neck 63a around which the detonation cord 66 (not shown in FIGS. 2 to 6 but shown in FIG. 1) is wound for storage. A tie-off slot 68 (see FIGS. 2 and 5) is located on the spool 63 and is used to secure a free end (not shown) of the detonation cord 66.

As can best be seen in FIGS. 4 and 6, the spool 63 also includes a central cavity 91 extending axially into the spool 63 from a lower end of the spool 63 (as viewed in the Figures) that receives and locates an upper section of the stake 61.

The stake 61 has an elongate shank 75 and a pointed end 77 and is a robust structure for anchoring the spool 63 and attached detonation cord 66 to the pit floor 91 proximate a safe hole 90a in preparation for tie-in, as described above in relation to FIG. 2.

The stake 61 is connected to the spool 63 so that the spool 63 and the stake 61 are movable as a unit. The spool 63 and the stake 61 may be separately formed as two components that are connected together. The shank 75 of the stake 61 is received in the cavity 91 of the spool 63 and supported via bearings 87 so that the spool 63 can rotate about a central axis of the shank 75 and thereby, in use facilitate the detonation cord 66 unwinding from the spool 63 as the booster 65 is positioned in the hole 90 in the pit floor 91—see FIG. 1.

The head of the spool 63 and the head of the booster 65 have the same neck profile 71 so that the spool 63 and the boosters 65 can cooperate with the same gripping mechanism (not shown) of a delivery assembly of the above-mentioned ISV.

The spool 63 and the booster 65 have the same-shaped recess 67 to allow a pusher 41 of a delivery assembly of the above-mentioned ISV to separately engage with the spool 63 and the booster 65. The engagement of the pusher 41 and the booster 65 is illustrated in the embodiment of the booster assembly shown in FIGS. 8, 9, and 16-18.

When used with the above-mentioned ISV, a plurality of booster assemblies 60 are stored in a suitable bomb-proof magazine or other suitable storage assembly of the ISV. The ISV is driven to a location proximate a hole 90 in the pit floor 91 shown in FIG. 1. In one embodiment of the ISV described in the co-pending International application mentioned above, a delivery assembly of the ISV transports a booster assembly 60 from the magazine to an intermediate transfer position (not shown) proximate the delivery position and then transports the booster 65 of that assembly to a loading position directly above the hole 90, with the spool 63 and the stake 61 remaining at the intermediate transfer position.

A loading assembly of the ISV (i) supports the booster 65 in the delivery position above an opening 94 to the hole 90 and (ii) moves the booster 65 downwardly into the hole 90 via movement of the pusher element 41 and inserts the booster 65 at an operative depth in the hole 90. FIG. 1 illustrates the booster 65 at the operative depth. The detonation cord 66 of the booster assembly 60 unwinds from the spool 63 as the booster 65 is moved into the hole 90. After the hole has been stemmed, the delivery assembly of the ISV moves the spool 63 and the stake 61 from the intermediate transfer position to the stemmed hole 90a and pushes the stake 61 via movement of the pusher element 41 into the pit floor 91 adjacent the stemmed hole 90a as shown in FIG. 1. The stemmed hole 90a is now ready to be connected to a detonation system to detonate the explosives in this and other holes in a required drill and blast array. The ISV can then move to the next hole and repeat the sequence of steps with another booster assembly 60 from the magazine.

The embodiment of the booster assembly shown in FIG. 7 is very similar to the embodiment shown in FIGS. 2-6 and the same reference numerals are used to describe the same structural features.

The spool 63 and the stake 61 are identical to the same components in the embodiment shown in FIGS. 2-6.

The booster 65 is different. Specifically, the booster 65 is the same booster 65 as the booster of the embodiment shown in FIGS. 8-13 and 16-18.

FIG. 7 also shows an internal guide 91 of the ISV that, when the booster assembly 60 is stored within a hollow storage tube (not shown) of a storage magazine (not shown), receives and supports a lower end of the stake 61 of the booster assembly 60 in the tube. The guide 91 includes outermost surfaces 93 that have a diameter that is marginally less than a diameter of an internal wall of the tube and, in use, contacts the inner wall and facilitates sliding movement of the guide in the tube. Specifically, the guide 91 includes a pair of spaced apart collars 95 that have the outermost surfaces 93. The spacing between the collars 95 is selected so that the guide 91 can move in a stable way within the tube. The guide 91 includes a cavity 97 extending downwardly (as viewed in FIG. 7) from an upper wall 99 of the guide for releasably receiving and supporting the stake 61. The shape of the cavity 97 corresponds to the shape of the lower end of the stake 61, as shown in the Figure, and the stake 61 is a snug fit in the cavity 97. With this arrangement, the stake 61 can be lifted clear of the guide 91 when the booster assembly 60 has been lifted to a raised position in the tube.

FIGS. 8-13 and 16-18 show details of another embodiment of a booster assembly 60 in accordance with the invention.

FIGS. 14 and 15 show another embodiment of a booster—identified by the numeral 65′—of the booster assembly shown in FIGS. 8-13 and 16-18.

In the following description of FIGS. 8-18 the references to a delivery assembly, a gripping mechanism of the delivery assembly, a loading assembly, and a booster engagement mechanism 49 and other components of a pusher 41 of the loading assembly are references to embodiments of the ISV that are described in the co-pending International application mentioned above.

The booster 65 shown in FIGS. 8, 9, 12 and 13 contains a large internal cavity 73 for storing a liquid explosive such as Powermite Thermo™ explosive.

In the booster 65′ shown in FIGS. 14 and 15 the cavity 73′ is reduced in volume for storing a solid explosive such as an HMX explosive.

A base 74, 74′ of the boosters 65, 65′ provides a rounded protrusion that in use cooperates with the engagement recess 67 that forms a booster dock 69 in the spool 63—for example, see FIG. 4. The connection between the recess 67 of the spool 63 and the base 74 of each booster 65, 65′ is a push fit: tight enough to support and connect the spool 63 and each booster 65, 65′ but easily separated.

The upper and lower portion of each booster 65, 65′ are identical to facilitate engagement with a common spool 63 and a pusher element 41 of a delivery assembly, as described below.

The spool 63 of the booster assembly 60 shown in FIGS. 8-13 and 16-18 has a central neck 63a around which the detonation cord 66 (not shown in the Figures of the embodiment) is wound for storage. A tie-off slot 68 (FIG. 11) can be located anywhere upon the spool 63 and is used to secure a free end (not shown) of the detonation cord 66.

With reference to FIG. 11, a brake mechanism 64 is provided within the spool 63 to limit the rate at which the detonation cord 66 is paid-out. The brake 64 comprises a pin that extends through the spool 63 and into contact with the stake 61 therein. Pushing or pulling on the pin increases or decreases the friction between the spool 63 and the stake 61 thereby altering the rate at which the spool 63 rotates about the stake 61.

With reference to FIG. 11, the stake 61 of the booster assembly 60 is pointed and robust for anchoring the spool 63 and attached detonation cord 66 to the pit floor 91 adjacent to a safe hole 90a in preparation for tie-in, as described above in relation to FIG. 1.

The head of the spool 63 and the heads of the booster 65, 65′ have the same neck profile 71 so that the spool 63 and each of the boosters 65, 65′ can cooperate with the same gripping mechanism of a delivery assembly.

The spool 63 and the booster 65, 65′ have the same shaped recess 67 to allow the pusher 41 of the delivery assembly to engage with the spool 63 and each of the boosters 65, 65′. The engagement of the pusher 41 and the booster 65 is illustrated in FIGS. 8 and 9.

FIGS. 12 and 13 illustrate the exterior neck profile 71 of the booster 65 for engagement with the gripping mechanism of the delivery assembly. As can be seen in FIG. 12, the neck profile comprises a base 101 extending around the perimeter of the booster 65 and two sides 103 extending from the base.

FIGS. 14 and 15 illustrate the exterior neck profile 71 of the booster 65′ for engagement with the gripping mechanism of the delivery assembly. The neck profile is similar to that shown in FIGS. 12 and 13.

FIGS. 13 and 15 illustrate an interior recess 67, 67′ in the head of the booster 65, 65′ forming a pusher dock 79, 79′ for engagement with a pusher 41 of the loading assembly. The interior profile of the recess 67, 67′ is shaped to correspond to the exterior profile of a conical nose 46 of the pusher 41 described further below in relation to FIGS. 16-18.

The booster engagement mechanism 49 of the pusher 41 of the delivery assembly is illustrated in FIGS. 9 and 16-18, with the booster 65 engaged with the pusher 41 in FIG. 17 and the booster 65 decoupled from the pusher 41 in FIG. 18. FIG. 16 shows the pusher 41 being inserted into the booster 65 as part of a process for coupling the booster 65 and the pusher 41 together.

The pusher 41 is an elongate element with an upper end and a lower end as evident from FIGS. 8 and 9 and a cylindrical side wall 121.

A large portion of the internal volume of the pusher 41 is filled with ballast 105, for example lead, to increase the weight of the pusher 41 and to assist the booster 65 moving downwardly through the explosive emulsion 93 (FIG. 1).

The booster engagement mechanism 49 is located in a lower section of the pusher 41.

The pusher 41 includes a chamber 117 in a lower section of the pusher 41. The chamber 117 is defined by a section 119 of the side wall 121 of the pusher 41, an upper partition member 123 that separates the chamber 117 and the ballast 105, and lower end element 125.

The pusher 41 also includes a plate 75 that is arranged for sliding movement along the length of the chamber 117. The plate 75 divides the chamber 117 into an upper chamber 117a and a lower chamber 117b.

The pusher 41 also includes a spring 43 in the upper chamber 117a. The spring 43 is selected so that it can extend axially downwardly and compress axially upwardly in response to sliding movement of the plate 75 in the chamber 117.

As can best be seen in FIG. 9, there is an air inlet 44 in an upper end of the pusher 41 and a central tube 115 for supplying air to the lower chamber 117b to allow the booster engagement mechanism 49 of the pusher 41 to be air activated, as shown in FIGS. 9 and 17. It is noted that reverse flow of air from the chamber 117 occurs when the air supply is cut-off.

The pusher 41 also includes a cylindrical actuator 45 that is connected at one end to the plate 75 and at the other end to the above-mentioned conical nose 46. The actuator 45 extends through an opening in the lower end element 125.

In addition, the pusher 41 includes a compressible member 48 that is mounted along a section of the length of the actuator 45 between the nose 46 and an end plate 75.

As can be appreciated from FIGS. 9 and 16-18, when the pusher 41 is inserted into the recess 67 of the pusher dock 79 of the booster 65, the booster 65 and the lower end element 125 of the pusher 41 form a closed chamber 127 which houses the compressible member 48. It can be appreciated from FIGS. 16-18 that the size of this chamber 127 can change.

Under normal operating conditions, it is necessary to supply air to the pusher 41 in order to couple together the booster 65 and the pusher 41. It is noted that when there is no air supply to the pusher 41, the pusher 41 will automatically decouple form the booster 65.

In use, in order to couple the pusher 41 to the booster 65, the pusher 41 and booster 65 are first axially aligned.

The conical nose 46 of the pusher 41 is then inserted into the recess 67 of the pusher dock 79 of the booster 65 until it cannot move forward from this engaged position—as shown in FIG. 16.

Compressed air is then fed into the inlet 44 and downwardly through the central tube 115 and into the lower chamber 117b. The air increases the pressure in the lower chamber 117b and causes the plate 75 to move upwardly in chamber 117 against the action of the spring 43. This upward movement of the plate 75 cause the actuator 45 and the nose 46 to move upwardly, thereby causing the compressible member 48 to be compressed in an axial direction and expanded outwardly in a radial direction. As the compressible member 48 expands in a radial direction the friction between the recess 67 and the compressible member 48 is increased locking the pusher 41 to the booster 65, illustrated in the coupled mode of FIG. 17.

To decouple the pusher 41 from the booster 65, the compressed air source (not shown) is de-activated, and reduces the pressure in chamber 117b, at which time the return spring 43 expands, pushing plate 75 downwardly and the actuator 45 away from the pusher 41 and allowing the compressed member 48 to expand in an axial direction and contract in the radial direction, reducing the friction between the recess 67 and the compressible member 48 and releasing the booster 65 from the pusher 41, illustrated in the decoupled mode of FIG. 18.

It is apparent from the above description that the booster assembly 60 of the invention makes it possible to efficiently and effectively transfer a booster 65 of the assembly 60 from a storage location to the hole 90 in the pit floor. In particular, it is apparent from the above description that the spool 63 and the stake 61 of the assembly 60 are important components of the booster assembly 60.

It will be appreciated by persons skilled in the art that numerous variations and modifications may be made to the above-described embodiments, without departing from the scope of the following claims. The present embodiments are, therefore, to be considered in all respects as illustrative of the scope of protection, and not restrictively.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, a limited number of the exemplary methods and materials are described herein.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

1. A booster assembly for use in a drill and blast operation, comprising in co-axial alignment: with an end of the spool being formed to receive and locate an end of the booster such that the booster is seated on the spool when the booster assembly is in an upright orientation in the storage position before moving the booster to the operative depth in the hole.

(a) a booster for initiating an explosion of an explosive material in a hole in a pit floor as part of a drill and blast operation;

(b) a spool and a detonation cord wrapped around the spool in a storage position outside the hole and connected to the spool and to the booster, with the spool being provided for allowing the detonation cord to be unwound from the spool as the booster is moved from the storage position to an operative depth in the hole and the spool remains in the storage position; and

(c) a stake for locating the spool in the pit floor proximate the hole after the booster is at the operative depth in the hole; and

2. The booster assembly defined in claim 1 wherein the booster and the spool have complementary formations that allow the spool to receive and locate the booster and thereby seat the booster on the spool.

3. The booster assembly defined in claim 1 wherein the booster is seated on the spool by being releasably coupled to the spool so that, in use, the booster is coupled to the spool in the storage position and can be moved clear of the spool as part of a process for moving the booster to the operative depth in the hole.

4. The booster assembly defined in claim 1 wherein the booster and the spool have complementary formations that allow the booster and the spool to be releasably coupled together by positively docking the booster on the spool and allow the booster to be released from the positive docking and moved clear of the spool as part of the process for moving the booster to the operative depth in the hole.

5. The booster assembly defined in claim 1 wherein the booster comprises a booster casing.

6. The booster assembly defined in claim 5 wherein the booster casing comprises an engagement feature, such as a collar, that facilitates engagement of the booster with a delivery assembly for transporting the booster assembly to a delivery position directly above the hole.

7. The booster assembly defined in claim 6 wherein the spool comprises a spool casing having an engagement feature, such as a collar, that facilitates engagement of the booster assembly with the delivery assembly for transporting the booster assembly to an intermediate transfer position proximate the delivery position directly above the hole.

8. The booster assembly defined in claim 1 wherein the spool comprises a brake to control the release of the detonation cord.

9. The booster assembly defined in claim 1 wherein the booster comprises formations that allow the booster to receive and locate a pusher element of a booster delivery assembly for applying a downwardly-acting force to move the booster downwardly from the delivery position into the hole to an operative depth.

10. The booster assembly defined in claim 9 wherein the booster and the pusher element are formed so that the pusher element is releasably coupled to the booster.

11. The booster assembly defined in claim 10 wherein the pusher element is releasably coupled to the booster by forming the booster with formations that allow the pusher element to be positively docked with the booster, with the formations including a recess in an upper end of the booster that can receive the pusher element.

12. A booster assembly for use in a drill and blast operation, comprising in co-axial alignment:

(a) a booster for initiating an explosion of an explosive material in a hole in a pit floor as part of a drill and blast operation;

(b) a spool and a detonation cord wrapped around the spool in a storage position outside the hole and connected to the spool and to the booster, with the spool being provided for allowing the detonation cord to be unwound from the spool as the booster is moved from the storage position to an operative depth in the hole and the spool remains in the storage position; and

(c) a stake for locating the spool in the pit floor proximate the hole after the booster is at the operative depth in the hole.