Explosive Booster

This application is a continuation of U.S. Nonprovisional patent application Ser. No. 18/456,882, filed Aug. 28, 2023. The entire contents of the above application are hereby incorporated by reference.

THIS INVENTION relates to blasting, specifically in mining applications. More specifically, the invention relates to the initiation of bulk explosives. The invention provides an explosive booster for initiating a bulk explosive. The invention extends to a loaded explosive booster and to a blasting assembly including the loaded explosive booster. The invention also provides a method of blasting using the loaded explosive booster.

BOOSTERS IN THE CONTEXT OF THE EXPLOSIVES INDUSTRY (i.e. “explosive boosters”) are used to generate, through detonation of a sensitive detonable booster formulation, sufficient detonation pressure to initiate and thus cause detonation of a less sensitive bulk explosive.

Challenges have come to arise in using explosive boosters that rely on sensitive detonable booster formulations that are, themselves, classified as explosives. Such challenges include, for example, supply chain and transport challenges.

It would be advantageous to be able to exploit, for the initiation and detonation of bulk explosives, sensitive detonable booster formulations that are not, themselves, classified as explosives.

Such exploitation provides its own challenges, however, particularly in achieving a sufficient detonation pressure.

The present invention finds application in the exploitation of sensitive detonable booster formulations that are not, themselves, classified as explosives, in the initiation and detonation of less sensitive bulk explosives.

ACCORDING TO ONE ASPECT OF THE INVENTION THERE IS PROVIDED an explosive booster for initiating, and thus causing detonation of, a bulk explosive, the booster including

The term “explosive initiator” referenced above, and hereinafter, includes within its meaning a detonator, e.g. a pyrotechnic detonator, and a blasting cap that serves to initiate the booster formulation inside the booster. Such an explosive initiator is typically in the form of an elongate container, of lesser diameter than that of the interior space of the booster, e.g. about 10 mm or less, that contains a primary explosive charge.

Typically, and in fact preferably, the central longitudinal axis of the initiator channel would be parallel to the central longitudinal axis of the interior space.

Preferably, the initiator locating formation projects into the interior space from beyond the base member, i.e. from outside of the interior space.

More particularly, the locating formation may extend along, and is thus connected to, the sidewall along at least a part of length of the locating formation, thus defining the initiator channel at the described location.

It will be understood that the initiator locating formation therefore interfaces with the sidewall, and that a part of the initiator locating formation therefore comprises, or is comprised by, the sidewall.

Furthermore, in projecting longitudinally into the interior space along the sidewall, the initiator locating formation is thus located such that the initiator channel extends longitudinally along the central longitudinal axis thereof.

The central longitudinal axis of the initiator channel is further in parallel with, while also being radially spaced with respect to, the central longitudinal axis of the interior space, along which the interior space longitudinally extends.

The interior space and the initiator channel may have each have a geometrically shaped cross-sectional outline, both preferably being circular.

The cross-sectional outlines of the interior space and the initiator channel may be substantially constant along their respective lengths.

The interior space may have a diameter of at least about 40 mm, more preferably at least about 50 mm, most preferably at least about 60 mm, e.g. 59.47 mm, even up to about 120 mm or more.

The interior space may extend along a length of from about 93 mm, e.g. extends along a length of about 93 mm.

The base member may have a thickness of from about 1.5 mm, e.g. having a thickness of about 1.5 mm.

The initiator locating channel may have a length sufficient to locate therein, and more specifically in a part thereof that is located inside the interior space, an elongate initiator that has a length of from about 55 mm to about 100 mm. The initiator locating channel may therefore, for example, have a length of about 113.50 mm.

Walls of the initiator locating formation that are located inside the interior space, that do not interface with the sidewall, may have a thickness of from about 0.6 to about 0.99 mm, e.g. about 0.8 mm.

The initiator locating formation may terminate at a distal end thereof that comprises a distal end wall that is located inside the interior space, which distal end wall be spaced from, i.e. located short of, a distal end of the interior space. More specifically, the end wall may be spaced a spacing of at least 20 mm, more preferably more than 20 mm, e.g. up to 30 mm, or more from the distal end of the interior space.

The distal end wall may have a thickness greater than that of the walls of the initiator locating formation that are located inside the interior space and that do not interface with the sidewall, for example being about 1 mm thick.

The body may further include a lacing formation defining an elongate lacing channel extending longitudinally along a lacing axis, through and along which to lace shock signal propagating means, e.g. shock tube, in use. In other words, shock signal propagating means may in use be laced through the lacing channel and thus along the lacing axis, thereby being connected to the booster. Such shock tube would in use typically terminate in an initiator, which would in use be located in the locating channel.

The lacing formation may be located such that the lacing channel extends longitudinally along a side of the body, outside of the interior space, and such that the lacing axis is parallel to both the central longitudinal axis of the interior space and the central longitudinal axis of the initiator channel.

Furthermore, the lacing formation may be provided such that the lacing axis is angularly spaced from the central longitudinal axis of the initiator channel about the central longitudinal axis of the interior space and is also radially spaced from the central longitudinal axis of the initiator channel along radii of the central longitudinal axis of the interior space, i.e. such that the lacing axis is radially further away from the central longitudinal axis of the interior space than the central longitudinal axis of the initiator channel.

The lacing channel may be of substantially constant cross-sectional outline along its length, which cross-sectional outline is preferably circular.

The lacing formation may extend along, and thus be connected to, the sidewall along at least a part of the length of the lacing formation. The lacing formation may therefore interface with the sidewall, and a part of the lacing formation may therefore comprise, or may be comprised by, the sidewall.

Other than at interfaces with the initiator locating formation and lacing formation respectively, the sidewall of the body may have a thickness of from about 2 mm to about 3.5 mm, e.g. about 2.28 mm.

The body may define a mouth at which the interior space terminates and through which a detonable booster formulation may be loaded into the interior space in use. The mouth may provide the distal end of the interior space. In one embodiment of the invention, the mouth may be defined by an end of the sidewall that is distally located with respect to the base member.

The mouth may be closable by a removable closure member, i.e. a lid or cap. The booster may therefore include a closure member for closing the mouth.

The closure member may be mountable to the body to close the mouth. In other words, the closure member may be configured such that the closure member is mountable to the body to close the mouth.

To this effect, the closure member and the body may have complementary thread formations that may be threaded to screw the closure member onto the body, thus mounting the closure member on the body and closing the mouth.

The complementary thread formations may be configured for effecting secure, i.e. tight, more specifically liquid tight, mounting of the closure member to the body, in a secured condition, by threading engagement of the complementary thread formations through e.g. two revolutions of the closure member about a screw axis. The screw axis may co-extend with the central longitudinal axis of the interior space.

The closure member may be configured to close the mouth liquid-tightly, and thus render the interior space liquid-tightly closed.

For example, the closure member may, in addition to being threaded for threading engagement with the complementary thread on the body, comprise a channel formation within which to seat a part of the body that defines the mouth.

The closure member and the body may be of different materials. Alternatively, and more typically, the closure member and the body may be of the same material.

The mounting member may be provided by the closure member, typically being located atop the closure member.

The mounting member may be configured to grip detonation signal propagating means, e.g. shock tube, and thus locate the booster relative to such detonation signal propagating means. For example, the mounting member may grip the detonation signal propagating means in use such that the booster hangs suspended from such detonation signal propagating means, preferably such that the central longitudinal axis of the interior space extends substantially vertically.

Typically, detonation signal propagating means would in use be located in such proximity to a bulk explosive that such location of the booster relative to such detonation signal propagating means would locate the booster relative to such bulk explosive in sufficiently close proximity for the booster to initiate the bulk explosive.

The mounting member may define a gripping axis, along which detonating signal propagating means gripped by the mounting member in use, may extend.

When located atop the closure member, the location of the mounting member atop the closure member may be such that, when the closure member has been screwed onto the body to close the mouth liquid-tightly, e.g. when the closure member is in the secured condition, the mounting member is radially spaced from the screw axis such that the gripping axis intersects the screw axis and the lacing axis respectively, thus extending substantially perpendicular to those axes.

Thus, in use, detonation signal propagating means, e.g. shock tube, may, with the closure member in the secured condition, be gripped by the mounting member along the gripping axis and be laced through the lacing channel along the lacing axis, bending substantially 90° in doing so.

Such detonation signal propagating means would in use terminate in an initiator, which would in use be located inside the initiator channel.

Thus, in use, a detonation initiating signal propagated along such detonation signal propagating means would reach and initiate such an initiator, causing it to detonate a detonable booster formulation contained in the interior space of the body in use which would, in turn, cause detonation of a bulk explosive in detonating proximity to the booster in use.

The booster may further comprise, on the closure member, a shielding formation located to shield detonation signal propagating means gripped by the gripping means, in order to prevent the detonation signal propagating means from being damaged. The shielding formation may extend parallel to the gripping axis. In one embodiment of the invention, the shielding formation may be a protrusion, e.g. an oblong protrusion, projecting from atop the closure to a distance further than the thickness of detonation signal propagating means to be used with the booster. Advantageously, such a shielding formation may also strengthen the structural integrity of the closure member.

The body may be of a thermally stable engineering polymer, i.e. a polymer that has a melting point greater than 200 to 250° C.

THE INVENTION EXTENDS TO a loaded explosive booster comprising

The interior space of the body may be partially filled with the detonable booster formulation. In other words, there may be air inside the interior space of the body in addition to detonable booster formulation, and the interior space of the body may therefore not be filled entirely (i.e. to the brim) with the detonable booster formulation.