Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A BOOSTER ASSEMBLY
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.
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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;
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(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.
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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.
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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.
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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,
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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:
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Figure 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;
Figure 2 is a perspective view of one embodiment of a booster assembly in
accordance with the invention in an assembled configuration;
Figure 3 is a side view of the booster assembly shown in Figure 2;
Figure 4 is a vertical cross-section of the booster assembly shown in Figure
3;
Figure 5 is a perspective view of the booster assembly shown in Figure 2, with
the booster of the assembly lifted clear of the spool and the stake of the
assembly;
Figure 6 is a vertical cross-section of the booster assembly shown in Figure
5;
Figure 7 is a perspective view of a second embodiment of a booster assembly
in accordance with the invention in an assembled configuration;
Figure 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 Figures
10-
13;
Figure 9 is a sectional view of the booster and the pusher element shown in
Figure 8 illustrating the engagement mechanism therein for selectively
coupling
together the booster and the pusher element;
Figure 10 is an enlarged side view of the spool and the stake of the third
embodiment of the booster assembly shown in Figures 8 and 9;
Figure 11 is an enlarged sectional view of the spool of the third embodiment
of
the booster assembly shown in Figures 8 and 9;
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Figure 12 is an enlarged side view of the booster of the third embodiment
shown in Figures 8 and 9;
Figure 13 is a sectional view of the booster shown in Figure 12;
Figure 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 Figures 2 to 13;
Figure 15 is a sectional view of the booster of Figure 14;
Figure 16 is an enlarged sectional view of the booster and the pusher element
shown in Figure 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;
Figure 17 is an enlarged sectional view of the booster and the pusher element
shown in Figures 9 and 16 illustrating the pusher element and the booster
coupled
together due to the compressible engagement member being in a compressed
state;
and
Figure 18 is an enlarged sectional view of the booster and the pusher element
shown in Figures 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
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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.
Figure 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 Figures
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 Figure 1, the drilled hole 90 is filled via the opening 94 to a
depth
of 9m 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 7m 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 Figure 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 Figures 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,
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(b) a spool 63 and a detonation cord 66 (not shown in Figures 2 to 6 but shown
in Figure 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 Figures 4 and 6, the booster 65 contains a large
internal
cavity 73 for storing a liquid explosive 81, such as Powermite ThermoTm
explosive.
A base 74 of the booster 65 (see Figures 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 Figures 2 to 6 but shown in Figure 1) is wound for storage. A tie-off
slot 68
(see Figures 2 and 5) is located on the spool 63 and is used to secure a free
end (not
shown) of the detonation cord 66.
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As can best be seen in Figures 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
Figure 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 Figure 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
Figures
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
Figure 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
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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. Figure 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 Figure 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 Figure 7 is very similar to
the embodiment shown in Figures 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 Figures 2-6.
The booster 65 is different. Specifically, the booster 65 is the same booster
65
as the booster of the embodiment shown in Figures 8-13 and 16-18.
Figure 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
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guide 91 can move in a stable way within the tube. The guide 91 includes a
cavity 97
extending downwardly (as viewed in Figure 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.
Figures 8-13 and 16-18 show details of another embodiment of a booster
assembly 60 in accordance with the invention.
Figures 14 and 15 show another embodiment of a booster¨ identified by the
numeral 65' ¨ of the booster assembly shown in Figures 8-13 and 16-18.
In the following description of Figures 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 Figures 8, 9, 12 and 13 contains a large internal
cavity
73 for storing a liquid explosive such as Powermite ThermoTm explosive.
In the booster 65' shown in Figures 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 Figure 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.
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The spool 63 of the booster assembly 60 shown in Figures 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 (Figure 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 Figure 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 Figure 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 Figure 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
Figures 8 and 9.
Figures 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
Figure 12, the neck profile comprises a base 101 extending around the
perimeter of
the booster 65 and two sides 103 extending from the base.
Figures 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 Figures 12 and 13.
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Figure 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 Figures 16-18.
The booster engagement mechanism 49 of the pusher 41 of the delivery
assembly is illustrated in Figures 9 and 16-18, with the booster 65 engaged
with the
pusher 41 in Figure 17 and the booster 65 decoupled from the pusher 41 in
Figure 18.
Figure 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 Figures 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 (Figure 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.
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As can best be seen in Figure 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 Figures 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 Figures 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 Figures 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 Figure 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 75t0 move upwardly in chamber 117 against
the
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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 Figure 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 Figure 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.
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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.
