AU3640000A - Spacer elements and process of use - Google Patents

Description

S&F Ref: 508037

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicants: Minteh Pty Ltd 3E, 1 7 UnwinI Blidge Road St Peters NSW 2044 Anstralia Soothjet Pty Ltd 1st Floor, 155 Brisbane Street Dubbo NSW 2830 Australia Sanleo Holdings Pty Ltd 1st Floor, 155 Brisbane Street Dubbo NSW 2830 Australia a Actual Inventor(s): Address for Service: Geoffrey Robbins Spruson Ferguson St Martins Tower 31 Market Street Sydney NSW 2000 Spacer Elements and Prc IP Australia Document 2 MAY 2000 Batch No: cess of Use Invention Title: ASSOCIATED PROVISIONAL APPLICATION DETAILS [33] Country [31] Applic. No(s) AU PQ0530 AU PQ0552 AU PQ1600 [32] Application Date 24 May 1999 25 May 1999 13 July 1999 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815c [R:\LIBW]29797.doc:brv Spacer Elements and Process of Use Technical Field This invention relates to at least one spacer element for use with an explosive in a bore hole or drill hole. This invention also relates to a process for utilising at least one spacer element with an explosive in a bore hole or drill hole. This invention further relates to an explosive system in a bore hole or drill hole comprising at least one spacer element and an explosive.

Background Art In the mining industry, bore holes or drill holes are drilled such that an explosive charge may be placed into the bore hole. This technique is widely used for open cast mining, for which the bore holes are typically 270mm and 31 mm in diameter.

In general, the preferred explosive, in terms of cost, ease of use and end result, is ANFO. This is a free flowing, granular product which is poured directly into the bore hole. The density of the poured explosive is generally in the range of 0.80-0.85.

There are many ground conditions that require less energy than that which is released by ANFO. The various techniques currently employed to reduce the energy in ~the bore hole are as follows: I) The use of air decks typically leads to a 20-40% reduction in explosives 20 used, compared to a full column. In a simplistic analysis, the end result could be estimated as if arising from a full column of explosives having a 20-40% reduction in density. That is, an explosive with an estimated effective density *o ~range of 0.50-0.65. This technique has the disadvantage that there is not enough work done in the air decked zones to give uniform rock movement and fragmentation.

2) The use of decoupled charges, whereby the explosive is contained in plastic or cardboard tubes, leads to a more uniform distribution of energy but suffers ~from the disadvantage that it is expensive and largely impractical for normal production blasting.

3) Low density ANFO, producing explosive prills having densities of less than 0.80, can be used. However, such explosives are more sensitive than high density ANFO and as such, are more sensitive and easier to initiate. The procedure of loading explosives in the bore hole therefore becomes less safe.

This technique further suffers from the disadvantage that the explosives lack the required mechanical strength and tend to break down to powder. This [R:\LJBH]00384.doc:LJG eventually results in an actual increase in the overall density of the explosive mix, which then becomes less sensitive, making detonation more difficult to initiate.

4) The use of ANFO blends, wherein ANFO is mixed with low cost fillers such as polystyrene, beads, styrene beads, sawdust, rice husks, etc has the effect of 'diluting' the ANFO and effectively distributing the prills, although it is important to avoid segregation of the components. However, the logistical problems relating to storage, handling and transportation of the large volumes of fillers necessary, is a major drawback.

Accordingly, it is an object of this invention to ameliorate the above disadvantages with respect to the prior art or, at least provide a useful alternative.

Summary of the Invention Throughout this specification, unless the context clearly indicates otherwise, the word, "comprise", "comprises", "comprising" or other variations thereof shall be understood as meaning that the stated integer is included and does not exclude other integers from being present even though those other integers are not explicitly stated.

The energy or pressure pulse generated by an explosive upon detonation is proportional to its density. The present invention relates to a product system for effectively lowering the density of a bulk explosive in a drill hole. The inventors have oooo found that the explosion efficiency of an explosive can be improved to more closely 20 match ground conditions around the bore hole by providing appropriate air spaces, or spaces of density lower than the density of the explosive charge, above and/or below, and/or adjacent to the explosive charge, so as to reduce the overall density of the explosive in the bore hole. The air spaces transmit shock waves to assist in breaking up rock, ore, coal body or any other in ground structure, during the explosion process.

25 Accordingly, in a first embodiment of this invention, there is provided a spacer element capable of insertion in a bore hole.

~In one formn there is provided an expandable spacer element capable of insertion in a bore hole wherein the shape of the spacer element when substantially fully expanded is such that when the spacer element is located in the bore hole the element can be positioned within the bore hole so as to permit explosive, optionally with fillers, to be placed in the bore hole adjacent the spacer element; and said spacer element is expandable with an expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, whereby said overall density of said expanded spacer element is [R:\LIBH00384a.doc: LG less than the density of said explosive and whereby the density of that part of the bore hole that comprises the expanded spacer element and the explosive adjacent the spacer element is less than what the density of said part of said bore hole would be if it were charged only with the explosive.

The spacer element may comprise a spacer body having a first end and a second end. The spacer body may be linked to said first and second ends in a manner selected from the group consisting of the spacer body being integral with said first and second ends and the spacer body being coupled with said first and second ends.

The spacer element may be expandable from a substantially lay flat configuration to an elongate annular shaped spacer element. The unexpanded spacer element is in the form of a substantially lay flat configuration.

The spacer element may comprise a material selected from the group consisting of plastics, polyethylenes, and high quality coextruded polymeric materials and wherein said material is said spacer element is substantially impervious to gas.

The spacer element may further includes means for expanding said element with an expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, from a substantially lay flat ;configuration to an expanded spacer element.

The means for expanding may comprise means for providing an inflating 20 substance said means for providing being located within said spacer element. The means S• for expanding may comprise means for providing an inflating substance located within said spacer element and is capable of being actuated by a user. The means for providing may be selected from the group consisting of at least one aerosol canister including an inflating substance, at least one aerosol canister including an inflating substance and 25 having delay means for delaying the release of the inflating substance on actuation of the S canister so as to permit the unexpanded element to be located in a bore hole after actuation of the canister, at least one aerosol canister including an inflating substance and having slowing means for slowing the release of the inflating substance on actuation of the canister so as to permit the unexpanded element to be located in a bore hole after actuation of the canister, coreagent separation means having co-reacting reagents separated from one another which on mixing release an inflating substance said contaiment means capable of being actuated so as to allow mixing of said coreagents and coreagent separation means having co-reacting reagents separated from one another which on mixing release an inflating substance said separation means capable of being actuated so as to allow mixing of said co-reagents said separation having delay means for [R:\LIBH]00384a.doc:

UG

delaying mixing of said co-reagents after being actuated so as to permit the unexpanded element to be located in a bore hole after actuation of the separation means.

The means for expanding may comprise means -for providing an inflating substance said means for providing being located within said spacer element and further comprising delay means for delaying the inflation of the spacer element on actuation of the means for expanding said delay means being operatively associated with said spacer element. The delay means is an outer material located about said spacer element which material fails once a certain pressure is reached inside said spacer element.

The means for expanding may comprise means for providing an inflating substance said means for providing being located within said spacer element and further comprising slowing means for slowing the inflation of the spacer element on actuation of the means for expanding said slowing means being operatively associated with said spacer element. The slowing means may be an outer material located about said spacer element which material slows the expansion of said element.

The spacer element may include means through which expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, can be passed so as to expand said element from a substantially lay flat configuration to an expanded spacer element. The means through which expanding material less dense than the density of an explosive to be placed in the 20 borehole adjacent the spacer element, optionally with fillers, can be passed so as to S S S expand said element may be a valve (in particular a one way valve such that it only lets the expanding material into the element but not out). The means through which expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, can be passed so as to expand said element may be a conduit. Typically means to close the conduit such as a 5cap, stopper or tie are used to close the conduit after the element has been filled with the expanding material.

The shape of said spacer element when substantially fully expanded may be that S.of an elongate substantially cylindrical member, such that the cross-sectional diameter of the expanded spacer element when inserted in a bore hole is less than the cross-sectional diameter of the bore hole so as to permit explosive to be placed in the bore hole alongside and adjacent the spacer element.

According to another form there is provided a substantially fully expanded spacer element capable of insertion in a bore hole wherein the shape of the substantially fully expanded spacer element is such that when the spacer element is located in the bore hole the element can be positioned within the bore [R:\LIBH]00384a.doc: UG hole so as to permit explosive, optionally with fillers, to be placed in the bore hole adjacent the spacer element; and said spacer element is expanded with an expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, whereby said overall density of said expanded spacer element is less than the density of said explosive, whereby the density of that part of the bore hole that comprises the expanded spacer element and the explosive adjacent the spacer element is less than what the density of said part of said bore hole would be if it were charged only with the explosive.

The expanded spacer element may comprise a spacer body having a first end and a second end. The spacer body may be linked to said first and second ends in a manner selected from the group consisting of the spacer body being integral with said first and second ends and the spacer body being coupled with said first and second ends.

The expanded spacer element may comprise a material selected from the group consisting of plastics, polyethylenes, and high quality coextruded polymeric materials and wherein said material is said spacer element is substantially impervious to gas.

The shape of said spacer element when substantially fully expanded may be that of an elongate substantially cylindrical member, such that the cross-sectional diameter of :-*the expanded spacer element when inserted in a bore hole is less than the cross-sectional 20 diameter of the bore hole so as to permit explosive to be placed in the bore hole alongside and adjacent the spacer element.

In another form, there is provided a spacer element capable of insertion in a bore hole whereby, on insertion of the element in the bore hole, the volume of the bore hole capable of being filled with an explosive is reduced. Generally, the spacer element is 25 filled with a material whose density is substantially lower than the density of the explosive a gas vapour or other low density material).

In one form there is provided a spacer element capable of insertion in a bore hole such that the volume of bore hole capable of being filled with an explosive is reduced. Usually, the overall density of the explosive in a bore hole having an explosive and spacer element inserted therein, is reduced.

Other embodiments of the spacer element include: According to a second embodiment of this invention, there is provided at least one spacer element capable of insertion in a bore hole wherein the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole, and whereby, on insertion of the element in the bore hole, the volume of the bore hole capable of being filled with an explosive is reduced.

R:\LIBHJOO3 84a.doc: UG Typically, after insertion of at least one spacer element in the bore hole, the volume of the bore hole that is fillable with an explosive is reduced by 20%-80%, 30%-70%, 40%-60%, 50%, 60%, 70%, 80%, 90%, 95%, more typically 10%-80%, 10%-70%, 10%-60%, 10%-50%, 10%-40%, 20%-70%, 20%-60%, 20%-50%, still more typically 10%-30%, 10%-20%, 20%-30%, 20%-40%, 10%, 40% of the volume of the bore hole.

Accordingly, in a third embodiment of this invention, there is provided at least one spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole, wherein the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which allows the insertion of an explosive in the bore hole.

Accordingly, in a fourth embodiment of this invention, there is provided at least one spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the at least one spacer element comprises a solid such as foam, fillers and the like or is a sock or enclosure filled with sawdust or other suitable S.fillers.

Accordingly, in a fifth embodiment of this invention, there is provided at least 20 one spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least one spacer element is substantially the same as or less than the cross sectional area of the bore hole and where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole.

Accordingly, in a sixth embodiment of this invention, there is provided at least *aa.

one spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, each spacer element comprising a spacer body capable of insertion in a bore hole, said spacer body having a first end and a second end.

[R:\LIBH]00384a.doc:UG Accordingly, in a seventh embodiment of this invention, there is provided a pair of spacer elements capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the pair of spacer elements is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the pair of spacer elements is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the pair of spacer elements and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, each spacer element comprising a spacer body having a first end and a second end.

Accordingly, in an eighth embodiment of this invention, there is provided at least one expandable spacer element capable of insertion into a bore hole so as to reduce the volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, each spacer ooo.

element comprising a spacer body having a first end and a second end Accordingly, in a ninth embodiment of this invention, there is provided at least 20 one expandable spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least a. one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole C is measured in a plane transverse to the longitudinal axis of the bore hole, each spacer element comprising a spacer body having a first end and a second end, wherein, each spacer element is capable of being aligned in a side by side arrangement along the length o°.and/or across the width of the bore hole.

Accordingly, in a tenth embodiment of this invention, there is provided at least one expandable spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole [R:\LIBH]00384a.doc: UJG is measured in a plane transverse to the longitudinal axis of the bore hole, each spacer element comprising a first end and a second end, wherein each spacer element is capable of being aligned in a side by side arrangement along the length and/or across the width of the bore hole, and further wherein the at least one spacer element is expandable from a substantially flat configuration to an inflated configuration in the bore hole.

Accordingly, in an eleventh embodiment of this invention, there is provided at least one expandable spacer element comprising an outer sleeve and an inner flexible enclosure which is substantially impervious to gas, capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, each spacer element comprising a first end and a second end, wherein each spacer element is capable of being aligned in a side by side arrangement along the length and/or across the width of the bore hole.

.f Accordingly, in a twelfth embodiment of this invention, there is provided at least one expandable spacer element capable of insertion in a bore hole so as to reduce the 20 volume of the bore hole such that the volume of the at least one spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least a one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, wherein the spacer element is attachable to an inflation means.

Accordingly, in a thirteenth embodiment of this invention, there is provided at least one expandable spacer element capable of insertion in a bore hole so as to reduce *0 the volume of the bore hole such that the volume of the spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, and the spacer element is attachable to an inflation means by way of a conduit, and wherein the spacer element is substantially the entire length of the bore hole.

[R:\LIBH]00384a.doc: ULJG Accordingly, in a fourteenth embodiment of this invention, there is provided at least one expandable spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, and the spacer element is attachable to an inflation means through a conduit comprising valve means, wherein the spacer element is substantially the entire length of the bore hole.

Accordingly, in a fifteenth embodiment of this invention, there is provided at least one expandable spacer element comprising an inflatable inner bag and an outer sleeve, the spacer element being capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, and the spacer element is inflatable by way of an 20 inflation means attachable to the spacer element through a conduit comprising valve means, wherein the spacer element is substantially the entire length of the bore hole and is substantially gas impervious.

Accordingly, in a sixteenth embodiment of this invention, there is provided at least one expandable, substantially gas impervious spacer element comprising an outer 25 sleeve and an inner inflatable bag, the spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, wherein the spacer element is substantially the entire length of the bore hole and the spacer element is attachable to an inflation means in the form of an air compression means through a conduit comprising valve means.

Accordingly, in a seventeenth embodiment of this invention, there is provided an expandable, substantially gas impervious spacer element comprising an outer sleeve and [R\LI BHIOO384a.doc: UG an inner inflatable bag, the spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that the volume of the spacer element is substantially the same as or less than the volume of the bore hole and which enables the insertion of an explosive in the bore hole, wherein the cross sectional area of the at least one spacer element is substantially the same as or less than the cross sectional area of the bore hole, where the cross sectional area of the at least one spacer element and bore hole is measured in a plane transverse to the longitudinal axis of the bore hole, wherein the spacer element is substantially the entire length of the bore hole and the spacer element is attachable to an inflation means in the form of one or more aerosol canisters capable of releasing pressurised gas and located within the spacer element.

According to a further embodiment of this invention there is provided a process for inserting an explosive and at least one expanded spacer element capable of insertion in a bore hole according to the invention, comprising the steps of: inserting into the bore hole said at least one expanded spacer element so as to permit the explosive to be placed in the borehole adjacent the spacer element; and inserting the explosive, optionally including fillers, in said bore hole adjacent said expanded spacer element, said overall density of said expanded spacer element being less than the density of said explosive, whereby the density of that part of the borehole comprising the spacer element and the explosive adjacent the spacer element 20 is less than what the density of said part of said borehole would be if it were charged only with the explosive.

Step may comprise: inserting into the bore hole said at least one expanded spacer element so as to permit the explosive to be placed in the borehole adjacent the spacer element, said spacer element having been expanded with an expanding material less dense than the density of said explosive, optionally with fillers.

Step may comprise: inserting into the bore hole said at least one expanded spacer element so as to *°*-pen-rmit the explosive to be placed in the borehole adjacent the spacer element, said spacer element having been expanded with an expanding material less dense than the density of said explosive, optionally with fillers, said expanding material being selected from the group consisting of gas, foam, polystyrene.

The borehole may include water therein and the process may further comprise: dewatering the borehole prior to said inserting the explosive.

The process may further comprise: lining the borehole with a borehole liner prior to step R: \LI BH]00384a.doc: UG The process may further comprise: inserting a borehole plug in the borehole.

The process may further comprise: inserting a borehole plug in the borehole prior to step to support a borehole liner; and lining the borehole with the borehole liner, prior to step The process of may further comprise: inserting a borehole plug in the borehole prior to step to support a borehole liner; lining the borehole with the borehole liner prior to step and inserting a borehole plug to close the borehole after step The process may further comprise: detonating the explosive in the borehole after step According to another form of the invention there is provided a process for inserting an explosive and at least one expandable spacer element capable of insertion in a bore hole according to the invention, comprising the steps of: inserting into the bore hole said at least one spacer element; expanding the at least one spacer element in the borehole until the at least one spacer element is substantially fully expanded; locating the fully expanded element in the borehole so as to permit the explosive to be placed in the borehole adjacent the spacer element; and 20 inserting the explosive, optionally including fillers, in said bore hole adjacent said *•'expanded spacer element, said overall density of said expanded spacer element being less than the density of said explosive, whereby the density of that part of the borehole comprising the spacer element and the explosive adjacent the spacer element is less than what the density of said part of said borehole would be if it were charged only with the explosive.

*Step may comprise: expanding the at least one spacer element in the borehole with an expanding material less dense than the density of said explosive, optionally with fillers.

o° :Step may comprise: expanding the at least one spacer element in the borehole with an expanding material less dense than the density of said explosive, optionally with fillers, said expanding material being selected from the group consisting of gas, fobam, polystyrene.

The borehole may include water therein and the process may further comprise: dewatering the borehole prior to said inserting the explosive.

The process may further comprise: lining the borehole with a borehole liner prior to step [R:\LIBH]00384a.doc:

LJG

The process may further comprise: inserting a borehole plug in the borehole.

The process may further comprise: inserting a borehole plug in the borehole prior to step to support a borehole liner; and lining the borehole with the borehole liner, prior to step The process may further comprise: inserting a borehole plug in the borehole prior to step to support a borehole liner; lining the borehole with the borehole liner prior to step and inserting a borehole plug to close the borehole after step The process may further comprise: detonating the explosive in the borehole after step In another form there is provided a process for inserting an explosive and at least one spacer element capable of insertion in a bore hole comprising the steps of: inserting into the bore hole said at least one spacer element wherein said spacer element is in a configuration selected from the group consisting of an unexpanded configuration and a partially expanded configuration, said bore hole being partially filled **.with water; oooo partially filling the spacer element with a filler material having a density selected ~from the group consisting of filler material having substantially the same density as water 20 and filler material having greater density than water to a level in the spacer element that *is about level with the surface level of water in the bore hole; expanding the partially filled spacer element in the borehole until the spacer element is substantially fully expanded; locating the fully expanded element in the borehole so as to permit the explosive to 1: 25 be placed in the borehole adjacent the spacer element; and inserting the explosive, optionally including fillers, in said bore hole adjacent said expanded spacer element, said overall density of said expanded spacer element being less than the density of said explosive whereby the density of that part of the borehole g comprising the spacer element and the explosive adjacent the spacer element is less than what the density of said part of said borehole would be if it were charged only with the explosive.

The process may further comprise: detonating the explosive in the borehole after step The spacer element may be in a configuration selected from the group consisting of an unexpanded configuration and a partially expanded configuration.

Other embodiments include: [R:\LIBH]00384a.doc: LJG According, in an eighteenth embodiment of this invention, there is provided a process for inserting at least one spacer element in a bore hole, comprising the steps of: inserting in a bore hole at least one spacer element as described in any one of the first to seventeenth embodiments of this invention; and inserting in a bore hole before, after or substantially at the same time as step an explosive.

Accordingly, in a nineteenth embodiment of this invention, there is provided a process for inserting at least one spacer element as described in any one of the first to seventeenth embodiments of this invention, comprising the steps of: inserting in a bore hole at least one spacer element as described in any one of the first to seventeenth embodiments of this invention; and inserting in a bore hole before, after or substantially at the same time as step an explosive; placing before, after or substantially at the same time as the insertion of the at least one spacer element and the explosive, a decking and/or a lining in the bore hole.

Accordingly, in a twentieth embodiment of this invention, there is provided a process for inserting two spacer elements into a bore hole, comprising the steps of: 9(a) inserting two spacer elements as described in any one of the first to seventeenth ooeo age. embodiments of this invention into a bore hole; and 6:00 20 inserting an explosive optionally together with fillers into the bore hole.

o°9Accordingly, in a twenty first embodiment of this invention, there is provided a process for inserting a pair of spacer elements in a bore hole, comprising the steps of: inserting a first spacer element as described in any one of the first to seventeenth embodiments of this invention into the bore hole; partially filling the bore hole with explosives and optionally fillers; 9(c) inserting a second spacer as described in any one of the first to seventeenth 9*9t embodiments of this invention into the bore hole; and filling the remainder of the bore hole with explosives and sufficient dirt to seal the bore hole.

Accordingly, in a twenty second embodiment of this invention, there is provided a process for inserting three spacer elements into a bore hole comprising the steps of: inserting three spacer elements as described in any one of the first to seventeenth embodiments of this invention into a bore hole; and inserting an explosive optionally together with fillers into the bore hole.

Accordingly, in a twenty third embodiment of this invention, there is provided a process for inserting three spacer elements in a bore hole comprising the steps of: [R:\LIBH]00384a.doc:

LJG

14 inserting a first and second spacer element as described in any one of the first to seventeenth embodiments of this invention, into the bore hole; partially filling the bore hole with explosives and optionally fillers; inserting a third spacer as described in any one of the first to seventeenth embodiments of this invention, into the bore hole; and filling the remainder of the bore hole with explosives and sufficient dirt to seal the bore hole.

Accordingly, in a twenty fourth embodiment of this invention, there is provided a process for inserting an explosive in a bore hole comprising the steps of: inserting at least one spacer element according to any one of the first to seventeenth embodiments of this invention into a bore hole; inserting in a bore hole before, after or substantially at the same time as step an explosive.

Accordingly, in a twenty fifth embodiment of this invention, there is provided a system in a bore hole comprising an explosive, and at least one spacer element as described in any one of the first to seventeenth embodiments of this invention.

sees Accordingly in a twenty sixth embodiment of this invention, there is provided a process for inserting at least one spacer element in a bore hole comprising the steps of: inserting at least one spacer element as described in any one of the first to oooo 20 seventeenth embodiments of this invention, into the bore hole in an uninflated S. 0.

configuration; and inflating the at least one spacer element by an inflation means until the at least *so& aone spacer element is substantially inflated.

°000 *se Accordingly, in a twenty seventh embodiment of this invention, there is 25 provided a process for inserting at least one spacer elements into a bore hole comprising the steps of: inserting at least one spacer element as described in any one of the first to seventeenth embodiments of this invention into a bore hole in an uninflated o configuration; inflating the at least one spacer element by an inflation means until the at least one spacer element is substantially inflated; and inserting an explosive into the bore hole.

Accordingly, in a twenty eighth embodiment of this invention, there is provided a process for inserting at least one spacer element into a bore hole comprising the steps of: [R:\LIBH]00384a.doc:

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inserting into a bore hole at least one spacer element, as described in any one of the first to seventeenth embodiments of this invention, wherein said spacer element is substantially the entire length of the bore hole; and inserting an explosive optionally together with fillers, into the bore hole.

Accordingly, in a twenty ninth embodiment of this invention, there is provided a process for inserting an explosive in a bore hole comprising the steps of: inserting at least one spacer element according to any one of the first to seventeenth embodiments of this invention, into a bore hole in an uninflated configuration; inflating the at least one spacer element by way of inflation means such as one or more aerosol cans or air compression means; and inserting in a bore hole before, after or substantially at the same time as step an explosive.

Accordingly, in a thirtieth embodiment of this invention, there is provided at least one spacer element according to any one of the first to seventeenth embodiments of this invention, characterised in that the spacer element is formed in the shape of a toroidal member.

Accordingly, in a thirty first embodiment of this invention, there is provided at least one spacer element capable of insertion in a bore hole so as to reduce the volume of the bore hole such that, when the at least one spacer element is substantially of the same diameter as the bore hole, the at least one spacer element is adapted so as to allow :.insertion of an explosive into the bore hole.

Accordingly, in a thirty second embodiment of this invention, there is provided *at least one spacer element as described in the thirty first embodiment of this invention, 25 wherein the at least one spacer element is shaped and/or comprises at least one aperture *so as to allow explosive into the bore hole once the at least one spacer element is inserted in the bore hole.

The longitudinal shape of the at least one annular spacer element may be cylindrical, rectangular or elliptical, for example. Typically, the cross sectional shape of 30 the at least one annular spacer body is circular or elliptical when the longitudinal shape of the annular spacer body is cylindrical or elliptical, and square shaped or rectangular shaped when the longitudinal shape of the annular spacer body is rectangular.

oe.•The at least one spacer element may be, for example, a toroidal shaped member, U shaped member, C shaped member, S shaped member, W shaped member, L shaped member, T shaped member, F shaped member, V shaped member, Z shaped member, J shaped member, X shaped member, A shaped member, B shaped member, D shaped [R:\LI BH]00384a.doc: UG member, E shaped member, G shaped member, H shaped member, I shaped member, K shaped member, M shaped member, N shaped member, P shaped member, Q shaped member, R shaped member, Y shaped member, corrugated member, or solid member comprising a aperture or interstitial spaces.

Accordingly, in a thirty third embodiment of this invention, there is provided a process for inserting at least one spacer element according to the thirty first or thirty second embodiment, into a bore hole, comprising the steps of: inserting at least one spacer element according to the thirty first or thirty second embodiment into the bore hole; and inserting an explosive into the bore hole.

Accordingly, in a thirty fourth embodiment of this invention, there is provided at least one spacer element according to any one of the first to seventeenth, thirtieth, thirtyfirst or thirty second embodiments wherein the at least one spacer element is capable of being inserted into a bore hole that includes water therein.

According to a thirty fifth embodiment of this invention, there is provided at least one spacer element according to any one of the first to seventeenth, thirtieth, thirtyfirst or thirty second embodiments of the invention, wherein the at least one spacer element is capable of being inserted into a bore hole that includes water therein, and wherein the at least one spacer element reduces the volume of a bore hole, upon insertion therein.

According to a thirty sixth embodiment of this invention, there is provided at least one spacer element according to any one of the first to seventeenth, thirtieth, thirty- •first or thirty second embodiments of the invention, capable of being inserted into a bore .*hole that includes water therein so as to reduce the volume of the bore hole and which 25 enables the insertion of an explosive into the bore hole, wherein the spacer element is capable of being contained within a substantially water resistant liner which is inserted into the bore hole.

"According to a thirty seventh embodiment of this invention, there is provided at least one spacer element according to any one of the first to seventeenth, thirtieth, thirty- 30 first or thirty second embodiments of the invention, capable of being inserted into a bore hole that includes water therein so as to reduce the volume of the bore hole and which enables the insertion of an explosive into the bore hole, wherein the spacer element is inflatable by the insertion of a liquid from an uninflated configuration to an inflated configuration.

According to a thirty eighth embodiment of this invention, there is provided at least one spacer element according to any one of the first to seventeenth, thirtieth, thirty- [R:\LIBH]00384adoc:LJUG 17 first or thirty second embodiments of the invention, capable of being inserted into a bore hole that includes water therein, so as to reduce the volume of the bore hole and which enables the insertion of an explosive into the bore hole, wherein a lower portion of the spacer element is inflatable by the insertion of a liquid up to the depth level of water to fonrm a column of liquid in the bore hole, and the remaining portion is inflatable by the insertion of a filler material, gas or suitable material to form a column of filler material or gas.

According to a thirty ninth embodiment, there is provided at least one spacer element of the thirty eighth embodiment wherein the filler material is a rigid foam and the gas is a hydrocarbon.

According to a fortieth embodiment of this invention, there is provided at least one spacer element according to any one of the first to seventeenth, thirtieth, thirty-first or thirty second embodiments of the invention, capable of being inserted into a bore hole that includes water therein, so as to reduce the volume of the bore hole and which enables the insertion of an explosive into the bore hole, wherein a lower portion of the spacer element is inflatable by the insertion of a liquid up to the depth level of water in the bore hole to form a column of liquid, and the remaining portion is inflatable by the insertion of a gas formed by an inflation means located within the spacer element, to form a column of entrapped gas.

According to a forty first embodiment of this invention, there is provided a process for producing at least one spacer element for insertion in a bore hole that includes water therein, comprising the step of: filling at least a first portion of the interior volume of the spacer element with a •liquid.

25 According to a forty second embodiment of this invention, there is provided a process for producing at least one spacer element for insertion in a bore hole that includes water therein, as described for the forty first embodiment, further comprising the step of: filling a second portion of the interior volume of the spacer element with a suitable filling material, gas or suitable material.

30 According to a forty third embodiment of this invention, there is provided a process for producing at least one spacer element for insertion in a bore hole that includes water therein, comprising the step of: filling the entire interior volume of the spacer element with a liquid.

According to a forty fourth embodiment of this invention, there is provided a process for producing at least one spacer element for insertion in a bore hole that includes water therein, comprising the steps of: [R:\LIBH]00384a.doc:LJG a) filling a first portion of the interior volume of the spacer element with a liquid up to a predetermined depth; b) filling a second portion of the interior volume of the spacer element with a column of rigid foam, entrapped gas or suitable material; and c) sealing the spacer element by suitable means.

According to a forty fifth embodiment of this invention, there is provided a process for producing at least one spacer element for insertion in a bore hole that includes water therein, comprising the steps of: a) filling a first lower portion of the interior volume of the spacer element with a liquid up to a predetennrmined depth; b) filling a second upper portion of the interior volume of the spacer element with a column of rigid foam, entrapped gas or suitable material; and c) sealing the spacer element by suitable means.

According to a forty sixth embodiment of this invention, there is provided a process for producing at least one spacer element for insertion in a bore hole that includes water therein, comprising the steps of: a) filling a first lower portion of the interior volume of the spacer element with a liquid up to a depth substantially equal to the level of water in the bore hole; b) filling a second upper portion of the interior volume of the spacer element with a column of rigid foam, entrapped gas or suitable material, from a depth substantially equal to the level of water in the bore hole up to a depth greater than the level of water in the bore hole; and c) sealing the spacer element by suitable means.

Typically the liquid in the forty first to forty sixth embodiments is water.

According to a forty seventh embodiment of this invention, there is provided a "method according to the forty fourth to forty sixth embodiment wherein the sealing step *comprises tying the spacer element, stitching the spacer element, plugging the spacer element, heat sealing the spacer element, or adhering the spacer element.

According to a forty eighth embodiment of this invention, there is provided a 30 process for inserting at least one spacer element into a bore hole that includes water therein, comprising the steps of: inserting at least one spacer element according to any one of the first to seventeenth, thirtieth to thirty fourth to fortieth embodiments of this invention, into the bore hole that includes water therein; and inserting an explosive into the hole.

[R:\LIBH]00384a.doc:

UG

According to a forty ninth embodiment of this invention, there is provided a process for inserting an explosive into a bore hole that includes water therein, comprising the steps of: pumping water resistant explosive into a bore hole that includes water therein; and inserting at least one spacer element according to any one of the first to seventeenth, thirtieth to thirty fourth to fortieth embodiments of this invention, into the bore hole.

According to a fiftieth embodiment of this invention, there is provided a process for inserting at least one spacer element into a bore hole that includes water therein, comprising the steps of: a) inserting a water resistant liner into the bore hole; b) inserting an explosive and at least one spacer element according to any one of the first to seventeenth, thirtieth to thirty fourth to fortieth embodiments of this invention, within the enclosed space of the water resistant liner.

According to a fifty first embodiment of this invention, there is provided a process for inserting at least one spacer element into a bore hole that includes water therein, comprising the steps of: a) pumping the water from the bore hole that includes water therein; b) inserting a water resistant liner into the bore hole to form an enclosed space within the water resistant liner; o inserting an explosive and at least one spacer element according to any one of the first to seventeenth, thirtieth to thirty fourth, thirty six to fortieth embodiments within the enclosed space of the water resistant liner.

25 According to a fifty second embodiment, there is provided a method according to the fifty first embodiment, further comprising the step of sealing the spacer element by sealing means.

According to a fifty third embodiment of this invention, there is provided a method according to the fifty second embodiment wherein, the sealing step comprises *o.30 tying the spacer element, stitching the spacer element, plugging the spacer element, heat sealing the spacer element, or adhering the spacer element.

The processes of the invention may include the step of closing the borehole after a.insertion of the spacer element and explosive.

[R:\LIBH]00384a.doc:

UG

According to a fifty fourth embodiment of this invention, there is provided a process for inserting an explosive in a bore hole that includes water therein, comprising the steps of: a) pumping the water from the bore hole that includes water therein; b) inserting a water proof or non water proof explosive in the bore hole; c) inserting at least one spacer element as described in any one of the first to seventeenth, thirtieth to thirty fourth, thirty six to fortieth embodiments of this invention; and d) filling the bore hole by adding suitable material such as drill cuttings or earth.

Typically, a bore hole is drilled to a depth of approximately 20-70 metres, more typically 50 metres, and the diameter of the bore hole is approximately 100 to 400mm, more typically 150 to 390mm, 190 to 370mm. Still more typically, the diameter is 200mm, 210mm, 220mm, 230mm, 240mm, 250mm, 260mm, 270mm, 280mm, 290mm, 300mm, 310mm, 320mm, 330mm, 340mm, 350mm. The bore hole is generally drilled at an angle and left unattended until the results of analyses of the contents of the bore hole are completed. Occasionally the bore hole may be partially filled with water. Suitable water lining members, decking arrangements for bore holes, sheets and the like may also be added to the bore hole and used in conjunction with the spacer element of this invention.

20 Typically the length of the spacer element varies depending on the length of the 9go• bore hole. The length of the spacer element is substantially the same as the length of the ~bore hole or shorter than the length of the bore hole, depending on the particular requirements. Typically, the length of the spacer element is up to 70m, typically up to typically up to 60m, typically up to 55m, typically up to 50m, typically up to typically up to 40m, typically up to 35m, typically up to 30m, typically up to typically up to 20m, typically up to 15m, typically up to Typically, the length of the spacer element is from 1% -100% of the entire length of the bore hole, still typically still typically 10%-90%, still typically 15% 85%, still typically 20%-80%, still typically 25%-75%, still typically 30%-70%, still 30 typically 35%-65%, still typically 40%- 60%, still typically 45%-55%. More typically, the length is 10%, 11%, 12 13%, 14%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, [R:\LIBH]00384a.doc: LJG 46%, 47%, 48%, 49%, 50%, 52%, 54%, 56%, 58%, 60%, 63%, 65%, 68%, 70%, 85%, 90%, 95% or 100% of the length of the bore hole.

Typically, the spacer element comprises a spacer body having a first end and a second end, capable of insertion in a bore hole. The spacer body having first and second ends may further comprise a first end and second end coupled together or integral with, a surrounding wall. Typically, the spacer element may be an annular element comprising an annular spacer body having first and second ends. The first or second ends of the annular spacer body may be integral with the annular body or one or both ends may be coupled with the annular spacer body. Coupling an end with the wall or spacer body may be achieved by gluing, taping, sewing, heat welding, adhesive welding, for example.

Generally, the coupling results in a gas tight seal between the end and the wall or body.

Typically, the spacer element may be solid, foam, other cellular products, liquid, semi-solid, semi-liquid or enclosed gas which is formed into a suitable shape so as to occupy a certain volume of space in a bore hole. Typical examples include a solid column or bag containing a free flowing powder such as sawdust. Still typically, the spacer element is inflatable and made of a flexible material. Still more typically, the spacer element is made of a flexible material such that the spacer element is substantially flat before inflation and is inflated after insertion in a bore hole to particular shapes as required, suitable for occupying a substantial portion of the volume of space in the bore hole.

Typically, the spacer element is a balloon shaped member, cylinder shaped member, toroidal shaped member, U shaped member, C shaped member, S shaped member, W shaped member, L shaped member, T shaped member, F shaped member,

V

.:member, W shaped member, L shaped member, T shaped member, F shaped member, A shaped -shaped member, Z shaped member, J shaped member, X shaped member, A shaped *25 member, B shaped member, D shaped member, E shaped member, G shaped member,

H

shaped member, I shaped member, K shaped member, M shaped member, N shaped **member, P shaped member, Q shaped member, R shaped member, Y shaped member, frusto-conical shaped member, ellipsoidal shaped member, cube shaped member, cone shaped member, spherical shaped member, rectangular prism shaped member, 4 30 tetrahedron, decahedron, dodecahedron, dome shaped member, hexahedron, heptahedron, icosahedron, nonahedron, octahedron, ring shaped member, sinusoidal shaped member, arch shaped member, arcuate shaped member, corrugated solid member, parabolic shaped member, oblong shaped member, or any suitable configuration which allows occupation of volume in a bore hole.

Still typically, the spacer element may be a solid member of any suitable shape with an aperture therein to allow insertion of an explosive. Still more typically, the [R:\LIBH]00384a.doc:

LJG

spacer element is a balloon shaped member or an ellipsoidal shaped member which is easily insertable and movable within the bore hole. Still more typically, the spacer element is capable of being aligned along the longitudinal axis or wall of the bore hole so as to allow a substantially even reduction in the volume of an explosive in the bore hole.

Still more typically, at least one spacer element is capable of being aligned across the width of the bore hole to occupy the volume of the bore hole.

Typically, the spacer element comprises a protective outer sleeve and a flexible gas and water impervious inner enclosure capable of containing a gas or vapour, such as a gaseous hydrocarbon, air, carbon dioxide, nitrogen etc. The protective outer sleeve and inner enclosure are both typically made of a material that does not rupture upon inflation.

Typically, the inner enclosure is in the form of a bag, and still typically, the inner enclosure is in the form of a balloon. Still typically, the inner enclosure is in the form of an annular body having first and second ends that are integral with or coupled with a spacer body, wherein typically a first end is closed and the second end is open and the second open end is capable of being closed by sealing means. Typically, the protective outer sleeve is in the form of a bag; still typically, the protective outer sleeve partially encases the annular body of the inner enclosure. Still typically the protective outer sleeve encases one sealed end and substantially partially encloses the body of the inner enclosure. Still typically, the protective outer sleeve encases substantially all of the inner enclosure comprising a spacer body and two ends, and still typically, the dimensions of the protective outer sleeve are just oversize of the dimensions of the inner enclosure.

S .Still typically, the spacer element is formed from a flexible but tough material, 00* •such as a plastic, into a plastic or plastic multi-layered bag and similar bags. The bag 0may be a polyethylene/nylon polyethylene multi-layered bag. These bags can be S 25 typically inflated to about 20-26 psi which will inflate the bag sufficiently to be inserted ~into the bore hole and provide the required shape to be positioned along the length and/or width of the bore hole to allow a substantially even reduction of volume of explosive in the bore hole. Typically, the bag does not need to be formned from a transparent material and therefore a broad selection of bag materials can be used. The bags may be clear to 0 30 enable an operator to see, for example, co-reagent canisters and so ensure they are adequately mixed prior to lowering the bag into the bore-hole. In such arrangements, the °°00 selection of bag materials is severely limited to those that are substantially clear or transparent.

The spacer element typically also comprises a protective outer plastic sleeve, which is generally an elongated, flexible sleeve, which encloses an inner plastic gas impervious enclosure capable of containing a gas. Typically, a gas impervious film is [R:\LIBH]00384a.doc:UG coated on either the inner portion, outer portion or whole of the spacer element.

Alternatively, the spacer element is integrally made of a gas impervious material.

Typically, there is at least one spacer element capable of insertion in the bore whereby, on insertion, the volume of space in the bore hole capable of being filled with an explosive, is reduced. Typically there are 1, 2, 3, 4 or more (e.g I to 500, 1 to 250, 1 to 100, 1 to 50, 1 to 10, 1 to 5) spacer elements in the bore hole. Typically, the spacer element includes a means of facilitating coupling of one element to another spacer element, for example, eyelets, velcro, wire, rope etc., said means being located at the surface of the body of the spacer element to enable at least two spacer elements to be optionally co-joined. The number of spacer elements inserted in the bore hole is dependent upon the size (length and/or diameter) of the bore hole, the desired intensity of the explosion and the explosive used. Typically, the explosive is ANFO.

Typically, the inflation means comprises a flexible conduit that is attachable to the spacer element to allow inflation thereof In the embodiment of the at least one spacer element having an inner bag and a protective outer bag or sleeve, the flexible conduit is attached either releasably or rigidly to the inner bag to allow inflation thereof The flexible conduit can be of any suitable type and typically comprises a plastic or rubber hose. Typically, the hose is rigidly fixed to an inlet of the spacer element such that it cannot be separated from the bag during normal use. Typically, the inflation means may also comprise the use of one or more aerosol cans typically located within the spacer element so as to release, for example, a gaseous hydrocarbon. Typically, the number of aerosol cans used is one per 15m of length of the spacer element. However, typically 1-10, typically 1-5, typically 1-3, more typically, 1, 2, 3, 4 or 5 numbers of aerosol cans are used. Typically the inflation means may also comprise the use of co- *25 reacting reagents, typically located within the spacer element such that when the reagents .•react, a gas is released. Typically, one co-reagent is a solvent (for example, water) and a ooo• further co-reagent is a solid mixture of an acid, for example citric acid or other similar acid, and a carbonate, for example sodium bicarbonate, ammonium carbonate, calcium carbonate, or other similar carbonate.

Typically, the spacer element may be weighted by suitable means such as stones or sand or soil or any other like material. The weights may be placed in the protective outer sleeve but are generally added to a pouch. The pouch may be formed by adhering or including integrally as part of the same material as that forming the outer sleeve, a pouch on the outside and proximal to the closed end of the sleeve. In this case, the closed end of the pouch may be sealed in a variety of shapes, typically a rectangular or triangular shape. Alternatively, prior to sealing the closed end of the outer protective [R:\LIBH]00384adocUJG sleeve of the spacer element, the pouch may be formed by folding the sleeve back onto itself and then heat sealing this end to form the desired shaped end and pouch which, as already mentioned may be in a triangular shape. The sealed, closed end may be reinforced to withstand any downward pressure as a result of the explosive travelling down the sleeve after the spacer element has been lowered down the bore hole. For example, the reinforcement may be in the form of strong adhesive tape applied to the closed end of the protective outer sleeve encasing the pouch.

The spacer element comprising a plastic enclosure is typically formed from a high tensile strength plastic, and is lightweight, durable, and not destroyed by the explosion. Usually, the plastic enclosure is a thin polymer material 2 to 10mm thick, 2 to 6mm thick, 100 m-1000am, 100 m-750pm, 100pm-500pm, 100pm-250pm, 100 m- 2 00pm, 1001m-150pm thick. Typically, 100am, 125pam, 150jm, 1 7 5am, 2 00pm, 2 50pm, 3 00pm, 3 50pm, 4 00pm, 4 50am, 500am, 6 00am, 7 001am, 8 0 0pm, 9 00pm, 1000pm thick. Polymers such as polyolefin

(C

2

-C

10 olefin), copolymers of different polyolefins, terpolymers of different polyolefins and blends of polyolefins. Examples of such polymers include polyethylene, polyethylene polymer with C 3 to C 10 alkenes, polyethylene/butadiene, polyethylene/vinyl acetate, different types of polyethylene including high density polyethylene (HDPE), low density polyethylene (LDPE), linearlow density polyethylene (LLDPE) and mixtures and blends of different types of polyethylene with each other and other copolymers, polypropylene, copolymers of polypropylene and blends with polyethylene and blends with polyethylene and polyethylene copolymers, propylene/butadiene, polyethylene polypropylene block copolymers and ethylene propylene

C

4

-C

6 diene terpolymers. Other suitable polymers include polyurethane blends, poly(vinylchloride), polyvinylchloride blends (see flexible polyblends listed in Table 1 page 461-463 of "Encyclopedia of Chemical Technology", Kirk Othmer, 3rd edition, Volume 18, John Wiley Sons 1982, incorporated herein by cross reference), and poly(ethyleneterephthalate) are examples of suitable polymers. The major materials for the sleeve are coextrusions, usually layers of polyethylene types over a nylon core (trapped nylon). Combinations of grades of polyethylene could also be effective depending on the strength required.

As described above, the spacer element is typically substantially gas impermeable or impervious. Generally, the plastic enclosure is also impermeable to water and diesel oil which is the normal fuel for commercial explosives.

The plastic enclosure component of the spacer element typically also has an antiblocking agent or abherent applied to the inner surface of the plastic or incorporated into the plastic to prevent the sleeve from sticking to itself. Examples of antiblocking [R:\LfBH00384a.doc:

UG

agents are silicones, waxes, for example hydrocarbon waxes such as petroleum waxes, natural waxes such as carnauba or spermaceti, waxy amides such as ethylene bis(stearamide), oleamide or erucamide; stearates for example zinc stearate, lead stearate, calcium stearate, magnesium stearate, barium stearate, cadmium stearate, aluminium stearate, lithium stearate; cellulose derivatives for example cellulose acetate, cellulose acetate butyrate or methyl cellulose; natural products such as flour, confectioners sugar, rice flour, sodium alginate, potassium alginate, or calcium alginate; inorganic abherents such as talc, mica, fumed silica, kaolin or attapulgite. The plastic itself may be an antiblocking plastic such as polyolefin, polyethylene, polypropylene, poly(1-butene), poly(vinyl acetate), poly(vinyl alcohol), poly(ethylene terephthalate), fluorocarbon polymers. Further examples of abherents are described in "Encyclopedia of Chemical Technology", Kirk Othmer, 3rd edition, Volume 1, John Wiley Sons 1982, the contents of which are incorporated herein by cross reference.

The spacer element according to the description above, may further comprise antistatic compounds applied to the outside surface or incorporated into the plastic to prevent sparks being generated when the spacer element is inserted into a bore hole.

Examples of antistatic compounds are amines such as ethoxylated amines or ethoxylated fatty amines; quaternary ammonium compounds; anionic surface active agents such as sulfonates or phosphates; or miscellaneous antistatic such as glycol esters, sulfated 20 waxes, fatty amides, polyhydric alcohol derivatives or inorganics. Further examples of antistatic compounds are described in "Chemical Additives for the Plastics Industry Properties, Applications, Toxicologies", Radian Corporation, Table A-2, Noyes Data Corporation 1987 and "Encyclopedia of Chemical Technology", Kirk Othmer, 3rd edition, Volume 3, John Wiley Sons 1982, the contents of which are incorporated herein by cross reference.

The spacer element according to the description above may also comprise additives applied to a surface or incorporated into the plastic. Examples of the types of additives which may be included are antioxidants, blowing agents, colorants, coupling agents, fillers, reinforcers, flame retardants, heat stabilizers, lubricants, preservatives, or stabilizers. Specific examples of plastics additives are described in "Chemical Additives for the Plastics Industry Properties, Applications, Toxicologies", Radian Corporation, Noyes Data Corporation 1987 and "Encyclopedia of Chemical Technology", Kirk Othmer, 3rd edition, John Wiley Sons 1982, the contents of which are incorporated herein by cross reference.

The flexible conduit may be rigidly attached to the spacer element.

Alternatively, the inlet of the spacer element may by releasably attached to the flexible [R:\LIBH]00384a.doc: UG conduit. The flexibility of the spacer element in the form of a bag, and the way it is positioned in the bore hole, may result in the inlet of the spacer element not being positioned in an upper portion of the bore hole.

The end of the flexible conduit not attached to the spacer element is typically attached to a canister containing pressurized gas. Such a canister can be in the form of a known type of aerosol can which can dispense a pressurized gas such as a hydrocarbon, carbon dioxide, nitrogen, etc. It is possible that the conduit may be attached to the aerosol can in a non-removable fashion such that the entire assembly can be bought and used as a kit.

It is typically found that an 11" diameter bore hole requires 100 g of hydrocarbon in an aerosol can to inflate the spacer element in the form of an inflatable bag.

Typically, a spacer element in the form of a deflated bag (typically loosely tied or wrapped into a plug form) is lowered into the hole by the flexible conduit. Either or both of the hose or spacer element may have calibrated markings to indicate the depth of the spacer element in the bore hole. When the desired position is reached, the aerosol can may be activated which will pass pressurised gas through the hose and into the bag to inflate the bag. The bag will then be inflated to the pressure dictated by the can. It can be seen that in a further variation, increasing the pressure in the can may vary the pressure inside the inflated bag. Thus, by being able to regulate the pressure within the bag, there is very little or no likelihood of the bag being improperly inflated.

o. Spacer element(s) may also comprise means to control the time required for inflation. Typically, the spacer element(s) are able to be lowered to a preselected depth in a borehole before inflation occurs. The spacer element may also comprise a sealed gas-tight inflatable container containing a pressurised vessel having pressure releasing means. The spacer element typically contains an inflating substance and a time delay liquid, and is adapted so that on operation of the pressure releasing means: the time delay liquid is discharged from the pressurised vessel, thereby causing a time delay b between the operation of the pressure releasing means and release of the inflating substance from the pressurised vessel, and (ii) after the time delay liquid has been discharged the inflating substance is discharged, thereby inflating the inflatable, gas impervious container of the spacer element. This allows the spacer element in the substantially flat configuration, to be inserted in a bore hole to a pre-selected depth and then inflated after a predetermined time, to provide an inflated spacer element which occupies a substantial volume of space in the bore hole. In addition, the spacer element may be stored in the uninflated condition for extended periods without deterioration or [R:\LIBH]00384a.doc: LJG premature inflation, and is suitably robust for transportation and use in harsh environments.

Typically, at least one spacer element may be inserted in a bore hole which includes a bore hole plug, as described in AU 93295/98, inserted therein. Other examples of borehole plugs are described in US 5,273,110, US 5,035,286, US 4,913,233,

ZA

92/9979, US 5,000,261, US 4,919,203, US 4,846,278, US 5,497,829, US 5,273,110, US5,035,286, US 5,000,261, US 4,919,203, US 4,913,233, AU656051, US 5,346,005, AU 579 395 and AU 595 887 the contents of which are incorporated herein by cross reference.

In a typical embodiment, a bore hole plug is inserted in the bore hole, positioned at a predetermined depth and secured, for example, by tethering means extended from the top of the bore hole and attached to the plug. The spacer element (in an expanded or unexpanded configuration) is inserted in the bore hole, and if not already expanded, the spacer element is inflated or filled with filler materials as described above. An explosive can then be inserted in the remaining volume of the bore hole. When the bore hole is fully charged, the stemming column of the bore hole can be filled with soil, dirt etc as described above, or with a further bore hole plug. The bore hole plug in the bore hole can be used to adjust the fillable volume of the bore hole. They can also be used to ensure the explosive and spacer element are most suitably positioned at a depth in the bore hole to match the underground conditions around the bore hole and explosive requirements thereof Insertion of a bore hole plug in a bore hole as described above is o:•o particularly useful when the bore hole has water included therein, as it can be used as a means to protect the spacer element and explosive from the water.

The pressurised vessel for use in the invention is typically a canister of metal or rigid plastic, inert both to the inflating substance and to the time delay liquid. Usually the container will be constructed from steel or aluminium.

The pressure releasing means is suitably a valve which, once opened, remains open. On operation of the pressure releasing means, the pressurised vessel is adapted to discharge the time delay liquid before discharging the inflating substance, suitably by means of a pipe or tube connected internally to the valve. The pipe or tube will be i oadapted to reach substantially to the bottom of the pressurised vessel when the time delay S liquid is more dense than the inflating substance, and will reach almost to the bottom of the layer of the time delay liquid when the liquefied inflating substance is the more dense phase. Typically, the time delay liquid is the more dense phase.

Known aerosol cans of the "flea bomb" type are suitable for use as the pressurised vessel in borehole plug assemblies of the invention. In these types of cans [R:\LIBH00384a.doc: UG the pressure releasing means is adapted so that, after the container is charged with the inflating substance and the time delay liquid, pressure is retained in the pressurised vessel until the pressure releasing means is operated, but when the pressure releasing means is operated the contents of the container will be released without interruption until the pressure inside the container is substantially equal to the pressure outside the container.

The inflating substance is a compressed gas, which may liquefy at the pressure in the pressurised vessel. Suitable inflating substances include halohydrocarbons such as tetrafluoromethane, methyl chloride, dichlorodifluoromethane, chlorodifluoromethane, dichloromonofluoromethane, ethyl chloride, trichloromonofluoro-methane, 1,2-dichloro- 1,1,2,2-tetrafluoroethane, 1,1-difluoroethane, 1,1-dichloro-l, 2 2 ,2-tetrafluoroethane, 1chloro-l,l-difluoroethane, ethyl fluoride and octafluorocyclobutane; hydrocarbons such as propane, butane or iso-butane; sulphur dioxide or dimethyl ether. Other compressed gases that may be used are carbon dioxide, nitrogen, helium, nitrous oxide, methane, ethane, oxygen and other like gases. Mixtures of one or more gases may also be used.

Usually, the pressurised vessel will be charged to a pressure in the range of from about 150 kPa to about 1000 kPa, more usually in the range of from about 170 kPa to about 520 kPa.

The time delay liquid and the inflating substance are selected so as to have low mutual solubility. Water is preferred as the time delay liquid. Most suitably, the inflating substance is a hydrocarbon or a mixture of hydrocarbons. Typically, the inflating substance is a mixture comprising from 30% to 70% by weight of butane and from 70% to 30% by weight of propane. More typically, the inflating substance is a mixture of approximately equal parts of propane and butane, that is, about 50% by weight of butane and about 50% by weight of propane. In that case, when water is used as the time delay liquid it forms a lower layer when charged into the pressurised vessel with the .inflating substance. When the inflatable borehole plug assembly of the invention is to be utilised under conditions of low (less than a few degrees C) ambient temperature, the time delay liquid may suitably comprise an antifreeze substance. Suitable antifreeze substances are well known and include ethylene/glycol, glycerol, propylene glycol, diethylene glycol, ethanol, methanol, iso-propanol and 1 -methoxy-2-propanol.

In one form of the spacer element of this invention, the spacer element comprises a single layer inflatable enclosure which is impervious to gas. Typically, the gas impervious inflatable enclosure is fabricated from plastic materials, including rubber or other elastomerics, nylon/surlyn coextrusions, polyethylene, polypropylene, or polyethylene/nylon/polyethylene coextrusions which have suitable strength and suitably low gas permeability. Preferably, the inflatable enclosure is fabricated from polyethylene [R:\LIBH]00384a.doc: UG or high quality coextruded polymeric material to minimise the risk of 'pinhole' flaws which are difficult to detect. Where nylon is included in the material of the containers, it should be of extrusion grade. Typically, the polyethylene or extrusion polymers used in fabrication of the spacer element have a thickness of approximately 150vim. Low linear low density polyethylenes are preferable to other types of polyethylene. Typically, polyethylene or coextrusion polymer material having an approximate width of 100mm- 150mm would be used to fabricate spacer elements that would typically give 20-30% volume reductions in 270mm and 311mm bore holes.

In another form, the spacer element of this invention, the spacer element in the form of an inflatable container comprises gas-tight inner and outer containers. Typically, such inflatable containers are multi-layer plastic bags. Plastic materials from which suitable multi-layer bags may be fabricated include rubber or other elastomerics, nylon/surlyn coextrusions, polyethylene, polypropylene, or polyethylene/nylon/polyethylene coextrusions which have suitable strength and suitably low gas permeability. Low linear low density polyethylenes are preferable to other types of polyethylene. Where nylon is included in the material of the containers, it should be of extrusion grade.

Typically, the spacer element in the form of an inflatable container of this invention, is a double-layer nylon coextrusion bag, coated with linear low density polyethylene. Low gas permeability can also be achieved by the use of a polyester inner layer or metallised plastic film. The inner and outer containers may be sealed by known means, for example heat welding, so as to ensure that the sealed inflatable container is gas-tight.

*o CThe borehole may be lined with a bore hole liner. Examples of borehole liners are disclosed in AU 64504/99 and US 5,198,613 the contents of which are disclosed herein by cross reference.

Typically, the inflation means attachable to the spacer element is an air compression means which is attachable to an inlet of the spacer element. The inlet may be a bladder valve arrangement so as to be connectable with a needle valve. The flexible 30 conduit typically comprises at one end, a needle valve which is insertable into the inlet or bladder valve of the spacer element. Valve means are also typically inserted between the inflation means in the form of an air compressor and the inlet or bladder valve.

Brief Description of the Drawings [R:\LIBH]00384a.doc: UG A number of preferred embodiments of this invention will now described, by way of example only, with reference to the accompanying drawings in which: Figure la is a longitudinal cross-sectional view of a bore hole comprising an explosive and two of spacer elements, in accordance with a further embodiment of this S invention; Figure l b is a cross-sectional plan view of a bore hole having spacer elements as depicted in Figure l a inserted therein; Figure 2 is a longitudinal cross-sectional view of a bore hole similar to that depicted in Figure la, except that there are 3 spacer elements, in accordance with a further embodiment of this invention; Figure 3a is an expanded plan view of a spacer element in a fully inflated configuration comprising an aerosol can, in accordance with a further embodiment of this invention; Figure 3b is an expanded plan view of the spacer element as depicted in Figure 3a, in an uninflated configuration; Figure 4 is an end cross-sectional view of the bore hole and spacer elements as depicted in Figure 2; Figure 5a is a longitudinal cross-sectional view of a bore hole comprising a spacer element in accordance with a further embodiment of this invention; 20 Figure 5b is an end cross-sectional view of the bore hole as depicted in Figure Figure 5c is a longitudinal cross-sectional view of a bore hole comprising the spacer element depicted in Figure 5a, and explosive, ready of detonation; Figure 6a is an expanded plan view of a spacer element according to further embodiments of this invention, in an uninflated configuration attached to an inflation means assembly; Figure 6b is an expanded plan view of the spacer element, as depicted in Figure 6a, in an inflated configuration; Figures 7a and 7b are longitudinal cross-sectional views of a dry bore hole with at least one expanded spacer element, an explosive and fillers inserted therein, in .o:i accordance with further embodiments of this invention; Figure 8a is a longitudinal cross-sectional view of a dewatered bore hole with at least one spacer element and an explosive within a water impervious liner, inserted therein, in accordance with a further embodiment of this invention; [R:\LIBH00384adoc:UG Figure 8b is a longitudinal cross-sectional view of a bore hole wherein water, an explosive and at least one spacer element are inserted therein, in accordance with a further embodiment of this invention; Figure 9a is a longitudinal cross sectional view of a bore hole wherein water and an elongate hose to pump water resistant explosive are inserted in the bore hole; Figure 9b is the bore hole as depicted in Figure 9a after a water-resistant explosive has been pumped into the bore-hole comprising water and the bore hole then sealed with fillers; Figures 10a and 10b are longitudinal cross-sectional views of a bore hole illustrating the pressure required in order to pump water into the entire length of the spacer element according to a further embodiment this invention; Figures I la, 1 b and I lc are longitudinal cross-sectional views of a bore hole wherein water and at least one spacer element are inserted therein, according to further embodiments of this invention; Figures 12a and 12b are longitudinal cross sectional views of a bore hole as depicted in Figures I lb and lc respectively, wherein water, an explosive and at least one spacer element are located therein; Figure 13 is a longitudinal cross sectional view of a bore hole, wherein water and at least one spacer element are located therein, according to a still further embodiment of this invention; 9**9 Figure 14 is a longitudinal cross sectional view of a bore hole, wherein two .o spacer elements and ANFO have been inserted therein, in accordance with a further oembodiment of this invention; 99 99 Figure 15 is a longitudinal cross sectional view of a bore hole, wherein two spacer elements and ANFO have been inserted therein, in accordance with a further embodiment of this invention Figure 16 is a perspective view of a compacted spacer element, according to still further embodiments of this invention; ~Figure 17 is an expanded plan view of a spacer element further comprising a pouch with a weight.

Best Mode for Carrying Out the Invention With reference to Figures l a and 1 b, there is shown a bore hole 10 having an upper end 12 and a lower end 14. The bore hole 10 further comprises a surrounding wall 16 which extends from the upper end 12 to the lower end 14 and is substantially circular in cross section. A pair of spacer elements comprising a first spacer element 20 and a [R:\LIBH]00384a.doc:

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second spacer element 22 are inserted into the bore hole 10. The spacer elements 20 and 22, respectively, both have a first end 24 and a second end 26 integral with or coupled to a spacer body 28 such that the spacer body 28 is generally circular in cross section. The first end 24 and the second end 26 are arcuately shaped in profile such that the spacer elements 20 and 22 form a substantially flattened ball shaped member or elongated balloon shaped member. The spacer elements 20 and 22 are typically made of a flexible, gas impervious polymeric material such as polyethylene, or co-extruded polymer material. Typically, the thickness of the polymer material is in the range of 100 1m- 2501dtm. The spacer elements 20, 22 are typically transported in a compact, deflated state to the bore hole and are inflated on site or in situ with an appropriate gas (eg, air, carbon dioxide, etc).

As shown in Figure 1 a, the spacer elements 20 and 22, respectively, are located in the bore hole 10 such that the longitudinal axis of each spacer element is generally along or parallel to the longitudinal axis of the bore hole 10. The spacer elements 20 and 22, respectively, are also aligned in the vicinity of the surrounding wall 16 of the bore hole 10 in a manner such that one of the spacer elements 20 or 22 is located above the other spacer element 20 or 22 in a column arrangement, thereby occupying a volume of space of the bore hole 10 along a substantial portion of the longitudinal axis of the bore hole 10. Detonators 66 and 68 are positioned in the bore hole. The spacer elements and 22 occupy a volume of space in the bore hole 10 such that the remaining volume of o ~the bore hole 10 capable of being filled with an explosive, is substantially reduced. An 9i9 oappropriate portion (depending on the required explosive force) of the remaining volume of space in the bore hole 10 is filled with an explosive 32, typically ANFO. The 9 explosive 32 is top loaded into the bore hole 10, making use of gravity to fill the bore hole 10. When the bore hole 10 is filled with the explosive 32 and the spacer elements °o and 22, the stemming column 13 at the upper end 12 of the bore hole 10 is filled with *9*t earth, dirt or soil 34 and the bore hole 10 is sealed. A lid (not shown) may be used to cover the dirt 34. The lid may be made of suitable material such as cardboard, plastic .999 material, metal or similar materials used for covering purposes. The explosive 32 is then ready for detonation by the detonators 66 and 68.

With reference to Figure 2, a bore hole 10 is filled with three spacer elements 21 and 22, an explosive 32, detonators 66 and 68, and dirt 34, in a similar manner to that described above for the bore hole 10 as depicted in Figures la and lb. In the arrangement shown, the three spacer elements 20, 21 and 22 are arranged such that they occupy a substantial volume of space within the bore hole 10 across the width of the bore [R:\LIBH]00384a.doc: LJG hole 10, as depicted. An end cross sectional view of the three spacer elements 20, 21 and 22 arranged in a bore hole 10 as depicted in Figure 2, is shown in Figure 4.

With reference to Figures 3a and 3b, there is shown a typical embodiment of a spacer element 20. The spacer element in this embodiment comprises an outer sleeve which is typically made of a flexible, durable, polyethylene material such that it is substantially wear resistant in the bore hole. The protective outer sleeve 35 encloses an inner bag 37 which is also typically made of a flexible polymeric material such as polyethylene or coextrusion polymer material. There is a fairly snug fit between the outer sleeve 35 and the inner bag 37. The protective outer sleeve 35 is of the about the same dimensions as the inner bag 37 and is made of a material such that it does not rupture upon inflation of the spacer element 20. The inner bag 37 is treated with an impervious film 39, or the inner bag 37 is made of a substantially gas impervious material such that the inner bag 37 is inflatable with a gas, for example, a hydrocarbon, a mixture of air with a hydrocarbon, carbon dioxide or other gases.

The spacer element 20 is inflatable by an inflation means 36. Typically, the inflation means 36 is a source of gas. For example, the inflation means 36, as depicted is in Figures 3a and 3b is a canister (such as an aerosol can) located inside the inner bag 37, which is capable of releasing a gas (such as a hydrocarbon, carbon dioxide etc).

Alternatively, the inflation means 36 could comprise a set of co-reacting reagents that are capable of releasing a gas. As shown in Figure 3b, the spacer element 20 is a sealed 6**E enclosure which, in the uninflated position, is substantially flat and does not occupy a o$ substantial volume of space. In Figure 3a, the spacer element 20 has been inflated by the ooo• gas released from the inflation means 36 (depicted as an aerosol can) and occupies a substantial volume of space.

Optionally, the spacer element 20 may have calibrated markings 50 to indicate the depth of the spacer element 20 in a bore hole 10. The spacer element 20 may be inflated before or after insertion in the bore hole 10 and may involve time delay means as previously described in the specification. However, in this embodiment, there is no time delay means depicted.

In relation to Figures 1, la, 2, 3a, 3b, and 4, for example, typically the spacer ~element(s) 20, 22 and/or 23 are fabricated from polyethylene or coextruded polymer S.•a:material of approximate width of 100mm-150mm and an approximate thickness of 150Ipm. Use of quality extrusion materials minimises the risk of pin hole flaws in the spacer elements, which are difficult to detect. The spacer elements 20, 22, 23 comprise an inflatable gas impervious bag 37, having a first end 24 and a second end 26 (wherein both ends are heat sealed), integral with or coupled to a spacer body 28. The spacer [R:\LIBH]00384a.doc:

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elements 20, 22, 23 so formed would give typically 20-30% volume reductions in 270mm and 31 1mm bore holes 10. Optionally, the spacer elements 20, 22, 23 may have a tag, string or similar attachment device to enable at least one spacer element to be linked to another spacer element. The spacer elements 20, 22, 23 are typically transported in a compact, deflated state to the bore hole and are inflated on site or in situ, with an appropriate gas.

With reference to Figure 5a, there is shown a bore hole 10 having an upper end 12 and a lower end 14. The bore hole 10 further comprises a surrounding wall 16 which extends from the upper end 12 to the lower end 14 and is substantially circular in cross section. The bore hole 10 is generally drilled at an angle but may also be substantially upright. At least one spacer element 20 is inserted into the bore hole 10. The spacer element 20 is substantially the entire length of the bore hole 10 and is located in the bore hole 10 such that the longitudinal axis of the spacer element 20 is generally along or parallel to the longitudinal axis of the bore hole 10. The spacer element 20 is also aligned in the vicinity of the surrounding wall 16 in a manner such that the spacer element 20 occupies the volume of space of the bore hole 10 along a substantial portion of the longitudinal axis of the bore hole 10. An end cross-sectional view of the spacer element 20 inserted in a bore hole 10 as depicted in Figure Sa, is shown in Figure The spacer element 20, as shown in the embodiment depicted by Figure comprises an inflatable gas impervious bag 37, defined by a first end 24 and a second end 26, integral with or coupled to a spacer body 28. Optionally, the spacer element 20 can have calibrated markings 50 on its outer surface to indicate the depth of the spacer element 20 in the bore hole 10. The spacer element 20 further comprises in the vicinity of the first end 24, a diaphragm or inlet or valve 25 for a needle 18, attachable to a flexible conduit 30 which in turn is connected to an inflation means 36, for example, an air compressor. The inflation means 36, in the form of an air compressor, is located on the surface towards the upper end 12 of the bore hole 10 and is able to inflate the spacer element 20 with compressed gas through the conduit o Figure 5c shows the inflated spacer element 20 as described above with reference to Figure 5a, inserted in a dry bore hole 10 having an upper end 12 and a lower end 14. The inflated spacer element 20 occupies a volume of space in the bore hole such that the volume of space in the bore hole 10 available to be filled with explosive 32, is substantially reduced. A detonator 66 is positioned in the bore hole. An explosive 32, typically ANFO of an appropriate density, is top loaded into the bore hole 10, and the stemming column 13 in the upper region 12 of the bore hole 10 is filled with earth, dirt, soil 34.

[R:\LIBH]00384a.doc:LJG With reference to Figures 6a and 6b, there is shown a typical embodiment of at least one spacer element 20. The spacer element 20 is typically made of a flexible, gas impervious material and is inflatable by an inflation means 36. The spacer element 20 in this embodiment comprises an outer sleeve 35 which is typically made of a durable, polyethylene material such that it is substantially wear resistant in the bore hole 10. The outer sleeve 35 encloses an inner bag 37 which is also typically made of a polymeric material such as polyethylene such that the outer sleeve 35 and the inner bag 37 are of the same dimensions and do not rupture. The inner bag 37 is treated with an impervious film 39 or the inner bag 37 is made of a substantially gas impervious material and is capable of being inflated with a gas, for example a hydrocarbon, a mixture of air with a hydrocarbon, carbon dioxide, or other gases. Accordingly, the inflation means 36 is a source of gas, such as an air compressor. Alternatively, as described above with reference to Figures 3a and 3b, the inflation means 36 may also comprise a system of coreacting reagents capable of releasing a gas, or one or more canisters, such as an aerosol can, which release pressurised gas.

The spacer element 20 is a sealed enclosure that, in the uninflated configuration shown in Figure 6a, is substantially flat and does not occupy a substantial volume of space. The spacer element 20 is inflated by gas that is released from the inflation means 36, depicted in the form of an air compressor. The released compressed gas inflates the 20 spacer element 20 through the flexible conduit 30 which is connected to valve means 38 ~which in turn is connected to the flexible conduit 30 which in turn is connected to the S 'p needle 18 which in turn is connected to the inlet 25 of the spacer element 20. The inlet of the spacer element 20 is a bladder valve which does not allow pressurised gas to escape the inner bag 37. Figure 6b shows the inflated spacer element 20 with the inflation apparatus 36 detached.

With reference to Figure 7b, an expanded spacer element 20, is inserted in a dry °obore hole 10 having an upper end 12 and a lower end 14. The expanded spacer element occupies a volume of space in the bore hole 10 such that the volume of space in the bore hole 10 available to be filled with explosive 32, is substantially reduced. A ooo* detonator 66 is positioned in the bore hole and an explosive 32, typically ANFO of an appropriate density, is top loaded into the bore hole 10, making use of gravity to fill the hole. The stemming column 13 in the upper region 12 of the bore hole 10 is filled with earth, dirt, soil 34, and the bore hole is typically sealed. The spacer element 20 is located in the bore hole 10 such that said spacer element 20 is lower than the stemming column 13. If, as illustrated in Figure 7a, the spacer element 20 extends through the stemming column 13 beyond the upper end 12 of the bore hole 10, it could provide a channel of [R:\LIBH]00384a.doc:

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weakness through which the high pressure gases from the explosion would vent, rather than performing work on the rock around the bore hole 10. A lid (not shown) may be used to cover the dirt 34. The lid may be made of any suitable material such as cardboard, plastics materials, metal or similar materials used for covering purposes. The explosive 32 is then ready for detonation by the detonator 66.

As described above, at least one spacer element 20 is capable of use within a dry bore hole 10. In such bore holes, the explosive is usually loaded from an upper end 12 of the bore hole 10 and the explosive 32 is inserted into the bore hole 10. The explosive 32 may be selected from: low density ANFO (ANFO with fillers such as sawdust) and typically having a density in the range of 0.4 to 0.8.

straight ANFO density typically having a density of about 0.82; and heavy ANFO density (ANFO/emulsion blends) typically having a density in the range of 0.82-1.35.

In a bore hole 10 that includes water therein, the bore hole 10 may first be dewatered then top loaded from the upper end 12 of the bore hole 10, as described above for dry bore holes. As shown in Figure 8a, a liner 41 is inserted into a wet bore hole after it has been dewatered to protect the explosive 32 and spacer element 20 from water.

The liner 41 forms a protective sheath such that the explosive 32 and spacer element 20 are inserted down the inner region of the liner 41. The stemming column 13 in the upper portion of the bore hole 10 is filled in the usual manner with dirt or earth 34. The liner S41, wherein the spacer element 20 and explosive 32 are placed, is sealed by suitable means, which in this embodiment is by tying the liner to form an enclosure.

Alternatively, as depicted in Figure 8b, water resistant explosive 32, typically water resistant ANFO such as heavy ANFO, is top loaded into the wet bore hole .together with at least one spacer element 20. Otherwise, the use of the spacer element S* and explosive 32 is as described above for the previous embodiments of this invention.

With reference to Figure 9a, if a wet bore hole 10 cannot be dewatered, then a pumpable water proof explosive 32, such as grease explosive, is inserted into the bore hole 10 by way of an elongate hose 43. Typically, the elongate hose 43 is made of a heavy duty material and is typically about 75mm in diameter. In Figure 9a, the elongate hose 43 is attached at one end to a water proof explosive pumping means (not shown) and the other end of the elongate hose 43 is inserted into a water column 45, towards the lower end 14 of the bore hole 10. Accordingly, the grease explosive 32 is pumped into the wet bore hole 10 from the lower end 14 towards the upper end 12 to give the desired [RA:LIBH]00384a.doc:UG result. Figure 9b illustrates the bore hole 10 when the pumpable, water proof explosive 32 has been bottom loaded in the bore hole The use of the spacer element 20 in wet bore holes 10 leads to a potential problem of locating the spacer element 20 within a water column 45 present in a bore hole 10. As shown in Figure 10a, a spacer element 20, in an unexpanded configuration, may be weighted by a weight 46, to enable the spacer element 20 to sink through a water column 45. However, this approach may suffer from the problem of the spacer element rising in the water column 45 unless it is suitably anchored. Further, with reference to Figures 10a and 10b, as the spacer element 20 is inflated, it displaces water and accordingly, high pressures may be required to overcome the water pressure and inflate the spacer element 20. For example, in a 50m bore hole there may be a 25m long water column 45 in the bore hole 10, and essentially a pressure of 1.5 psi per metre of water is required to displace the water. Similarly, fluid explosive would pressurise the top exposed region of the spacer element.

Accordingly, Figures la, 1 b and 1 lc illustrate further embodiments of this invention. In Figure 1 la, a spacer element 20 is weighted and lowered through a water column 45 in a bore hole 10. Instead of being inflated with gas, a first portion 47 of the S interior volume of the spacer element 20 is filled with water, such that the level of water .in the spacer element is about level with the level of water in the bore hole 10. The 20 spacer element 20 expands from an unexpanded configuration to an expanded •configuration up to the level of the water column 45 in the bore hole 10. However, above this level, the level of water in the spacer element 20 would rise above the level of the *o water column 45, and toward the upper end of the bore hole 10 the spacer element °•would become progressively heavier and difficult to maintain.

Accordingly, further embodiments are shown in Figures 1 b and 1 c, whereby instead of continuing to fill the spacer element 20 with water, a second portion 49 of the spacer element 20, is filled with material having density less than the density of water, for example, entrapped gas, foam, polystyrene, etc. In Figure 1 lb, a second portion 49 of the spacer element 20, located above the first water-filled portion 47, is filled with rigid foam to a depth below the upper end of the bore hole 10. In Figure 1 Ilc, there is shown a similar embodiment as described in Figure lb, whereby a second portion 49 of the spacer element 20, is filled with entrapped air and this portion is sealed with sealing means With further reference to Figures 1 la, 1 lb and 1 Ilc, the uppermost portion 53 of the spacer element 20 must be sealed off, so as not to infringe upon the stemming column 13 (which is necessary to prevent venting of gases during or after the explosion) of the [R:\LIBH]00384a.doc: UG bore hole 10. Accordingly, Figures 12a and 12b show the respective uppermost regions, 49 and 53 of the spacer element 20 being sealed with suitable sealing means 55 (such as stitching, or forming a tie or knot, for example), below the stemming column 13.

Thus, with reference to Figures 12a and 12b, when pumpable explosive 32 begins to fill the wet bore hole 10 from the bottom of the hole upward, the combination of water plus foam, and/or water plus air plus gas, in the spacer element 20, prevents the spacer element 20 from being flattened. The desired reduction in volume of the bore hole 10 available to be filled with explosive 32, is thereby maintained.

In Figure 13, there is shown an embodiment where the bore hole 10 is totally wet or contains water along most of its length. In this drawing, the spacer element does extend through the stemming column 13 in the upper end 12 of the bore hole and the spacer element 20 is filled with a liquid such as water up to the entire volume of the spacer element 20. In this embodiment, the stemming integrity is not substantially affected.

As illustrated in the following examples, with reference to Figures 14 and 15, in use, the present invention improves explosive efficiency, that is, an effective explosion is achieved using less explosive. Insertion of spacer elements 20 and 22 in a bore hole substantially reduces the volume of bore hole 10 capable of being filled with an explosive S "32, typically ANFO. Generally, the spacer elements 20 and 22 are filled with a material whose density is substantially lower than the density of the explosive 32 a gas vapour or other low density material), whereby the overall density of the explosive 32 in S" the bore hole 10 is usually reduced. Two examples of the dimensions of a spacer element inserted in a bore hole 10, together with the corresponding reduction in the required amount of the explosive ANFO, are illustrated below: Insertion of a spacer element (Mini Mizer) 20 comprising a gas inflated tube *°15m long x 178mm in diameter, into a bore hole 10 will reduce the required amount of ANFO explosive 32 by 2 0kg/metre. For example: 31 mm diameter bore hole: ANFO reduced from 61 kg/hole to 41 kg/hole 2 9 0mm diameter bore hole: ANFO reduced from 53 kg/hole to 33 kg/hole 2 7 0mm diameter bore hole: ANFO reduced from 46 kg/hole to 26 kg/hole The spacer element (Mini Mizer) 20 can be located at any location required in the bore hole 10, typically at a geologically weaker strata. This will reduce the volume of ANFO 32 in the required section, while maintaining the required overall explosive energy. At least one spacer element (Mini Mizers) 20, 22 can be located in advance of the charging truck, hours to days in advance. The use of the spacer elements (Mini [R:\LIBH]00384a.doc:

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Mizers) 20, 22 increases the explosive truck hole charging capacity, i.e. 20% reduction of ANFO per hole gives a 20% increase in bank cubic meters (BCM) charged, as is further illustrated below: 14t. truck fully charges at 1000kg per hole 14 holes 14t. truck [minimizer at 20%] charges at 800kg per hole 17.5 holes 14t. truck [minimizer at 33%] 667kg per hole 20.9 holes With reference to Figure 14, there is shown a 290mm diameter bore hole Typically, 53kg/m of ANFO 32 is required for a bore hole 10 comprising an upper stem, A (depth 6m), an upper portion of shale/mudstone medium-soft rock, B (depth 25m), and a lower band of sandstone, C (depth 20m). For the explosion: Area C: fully charged with explosive: 53x20 1060kg ANFO Area B: spacer elements 20 and 22, 15m and 10m in length respectively, are inserted: 1 x 15m x 178mm diameter 20kg per hole less 300kg 1 x 10m x 178mm diameter 20kgh less 200kg The bore hole 10 wherein the two spacer elements 20 and 22 are inserted, requires 1832kg of ANFO, compared to a fully charged bore hole which requires 2332kg (53kg/hole x 44m) of ANFO. This represents a saving of 500 kg of ANFO.

With reference to Figure 15, there is shown a 2 90mm diameter bore hole 20 comprising an upper portion of medium-soft rock mudstone/shale (35m) and a lower portion of hard rock sandstone (15m). The amount of ANFO explosive required for the 50m bore hole, is 53kg/m. Coupled spacer elements 20 and 22, each having dimensions 15m x 178mm, are inserted into the bore hole 10 and located in the upper (35m) portion of the bore hole 10. The saving for ANFO explosive is 300kg of ANFO per spacer 25 element and a saving of 600kg ANFO for both spacer elements. After insertion of the spacer elements 20 and 22, together with ANFO 32 into the bore hole 10, detonators 66 and 68, for example in the form of non-electric detonator leads, are placed in bore hole 9. 10. The ANFO 32 is then detonated in the bore hole 10 and the presence of spacer elements 20 and 22 reduces the pressure pulse developed by the detonated ANFO 32.

However, the pressure pulse is still sufficient in intensity to satisfy the requirements for blasting the ground surrounding the bore hole.

In relation to Figures 5a, 5b and 5c, for example, in use, a spacer element comprising a single inflatable gas impervious bag 37, is lowered into the bore hole typically by the flexible conduit 30. The flexible conduit 30 or the spacer element may be optionally marked with calibrated depth indicators 50. When the spacer element [R:\LIBH]00384a.doc:UG has been lowered to the desired position, the spacer element 20 can be inflated by the inflation means 36 to provide a source of pressurised gas to inflate the inner bag 37. The source of pressured gas may also be a canister or aerosol can arrangement as previously described in the specification, or may be other means such as the use of co-reacting reagents which can release a gas, as previously described in the specification. Typically, the inlet 25 of the spacer element 20 may be releasably attachable to the flexible conduit for example by a needle 18. The flexible conduit 30 typically incorporates the valve means 38, such as a one-way valve, to prevent the gas or inflatable substance in the spacer element 20 from escaping back up the inlet 25. An appropriate portion of the remaining volume of the bore hole 10 is then substantially filled with a pre-determined volume of explosive 32, in conjunction with other fillers such as beads, polystyrene, styrene beads etc, as required to fill the remaining portion of the bore hole 10. Dirt and soil 34, etc are used to fill the stemming region 13 at the top of the bore hole 10, to prevent venting of gas during or after the explosion. The explosive 32 in bore hole 10 is then ready for detonation.

In relation to Figures la, lb, 2, and 4, for example, in use, the bore hole 10 is filled with at least one spacer element 20, 21, 22 so as reduce the volume of space in the bore hole 10 capable of being filled with an explosive 32. The number of spacer elements 20, 21, 22 used will depend on the overall desired density of explosive 32 in the 20 bore hole 10, and the reduction of energy required for the explosion. After inserting the spacer elements 20, 21 or 22 into the bore hole 10, the remaining volume of space is substantially filled with an explosive 32, typically ANFO. However, other fillers may be used as required, such as beads, polystyrene, styrene beads, etc. After the bore hole 10 is S filled with the required amount of explosive 32 and at least one spacer element 20, 21, 22, the bore hole 10 is sealed with dirt or soil 34. The bore hole 10 is then ready for •detonation of the explosive 32.

In relation to the spacer element depicted in Figures 6a, 6b and 7b, for example, in use, the bore hole 10 is filled with the spacer element 20 so as reduce the volume of o* space in the bore hole 10 that is available to be filled with explosive 32. The spacer element 20 is typically the entire length of the bore hole 10. The spacer element 20 is inserted in an uninflated configuration into the bore hole 10. The inflation means 36, such as an air compressor, pumps compressed gas through the flexible hose 30 into a needle 18. The flexible hose 30 comprises a valve 38, such as a one way valve, between the air compressor 36 and the needle 18. The needle 18 is inserted into a diaphragm or inlet 25 of an inner bag 37 of the spacer element 20. A suitable slit, aperture or other port [R:\LIBH100384a.doc:UG is provided in the protective outer sleeve 35 such that the gas impermeability of the spacer element 20 is not compromised.

With further reference to Figure 7b, after the spacer element 20 is inflated, the bore hole is typically filled with explosive 32 and other suitable fillers to give the required overall density of explosive in the bore hole 10. The bore hole 10 is sealed by filling the stemming column 13 with dirt or soil 34, and the bore hole 10 is then ready for detonation of the explosive.

With reference to any one of Figures 1 to 16, generally, the spacer element 20 is made to suit any bore hole length. Further, the outer surface of the spacer element 20 as described in any of the above embodiments of the invention, may be marked with calibrated depth indicators 50. The calibrated markings 50 are advantageous because bore holes are usually drilled to a certain depth and the spacer element 20 may be unrolled into a dry bore hole 10 until the calibrated marking corresponds to the known depth of the dry bore hole 10. Usually, the length of the spacer element 20 unrolled into the bore hole 10 is the same length or less than the bore hole 10. If the spacer element is unrolled into a bore hole 10 that includes water therein, the spacer element 20 is unrolled as far as possible to avoid too much water from over flowing the bore hole -;-With reference to Figure 16, generally a first end 56 of the spacer element 20 is S S affixed to a rod 60 and the spacer element rolled around the rod to provide a compact 20 package. For example, the spacer element 20 as depicted, is rolled around a rod 60, such that a second end 58 of the spacer element is accessible on the outer surface of the rolled package. With the spacer element 20 rolled in this fashion, the attachment, adherence or .:.fornnation of a pouch 62 to the spacer element, on site, is facilitated. As illustrated, the end 58 of the spacer element 20 has been folded and sealed with sealing means (such as heat sealing, adhesive, etc) to form a pouch 62. The pouch 62 is readily accessible by the user on site without having to unroll the sleeve. A weight such as stones, soil, sand or any other weight, can then be placed in the pouch. The insertion of a weight facilitates the spacer element 20 reaching the required depth in the bore hole. The pouch may further act as a protective scuff barrier to maintain the integrity of the spacer element With reference to Figure 17, in one formn the spacer element 20 has a means or device 64 tags, eyelets, velcro, fasteners, string, etc) to facilitate coupling the spacer element 20 to at least one other spacer element. The means or device 46, is typically located on the exterior portion of the spacer element 20, for example, on one or both end(s) 24, 26 or on the spacer body 28. In the embodiment shown, a protective outer sleeve 35 partially encloses the inner inflatable enclosure 37 and gives additional strength [R:\LIBH]00384a.doc:LJG 42 to the inflated spacer element 20. A weight 46 is placed in the pouch 62 to facilitate the traversal of the spacer element 20 to the required depth in a bore hole.

Typically the explosive 32 is ANFO or other desirable explosive. A lid may be placed over the opening of the bore hole 10 to prevent the bore hole 10 from filling up with dirt and rain water. Usually the lid will be made of any material such as cardboard, plastic, corrugated cardboard, wood, metal or ceramic.

The advantages of the spacer element(s) according to this invention include: the spacer element(s) are inexpensive, versatile, readily manipulated and easy to insert into a bore hole; the diameter, length and shape of the spacer element can be adjusted to meet the specific requirements of a given bore hole; the spacer element(s) are capable of withstanding the explosion force in the bore hole; the spacer element(s) are capable of providing a uniform reduction in the effective density of the bore hole; the capability of utilising the spacer element(s) of this invention with bore hole liners, bore hole gas bags, and bore hole decking arrangements to optimise explosion efficiency; standard explosives, eg ANFO, can be used, as well as standard operating *20 procedures for insertion of explosives into a bore hole.

The capability of achieving a continuous column of explosive in the bore hole for improved effectiveness and efficiency; the capability to control the specific amount of explosive required for a bore hole, thereby minimising costs and improving cost-effectiveness; a commercially useful, cost effective and beneficial alternative over the prior art.

S• Modifications and variations such as would be apparent to a skilled person are deemed to be within the scope of this invention. It is also to be understood that this invention should not be restricted to the specific embodiment(s) described above.

00 0 [R\LIBH00384a.doc:LJG

Claims (31)

1. An expandable spacer element capable of insertion in a bore hole wherein the shape of the spacer element when substantially fully expanded is such that when the spacer element is located in the bore hole the element can be positioned within the bore hole so as to permit explosive, optionally with fillers, to be placed in the bore hole adjacent the spacer element; and said spacer element is expandable with an expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, whereby said overall density of said expanded spacer element is less than the density of said explosive and whereby the density of that part of the bore hole that comprises the expanded spacer element and the explosive adjacent the spacer element is less than what the density of said part of said bore hole would be if it were charged only with the explosive.

2. The spacer element of claim 1 comprising a spacer body having a first end and a second end.

3. The spacer element of claim 2, wherein said spacer body is linked to said first and second ends in a manner selected from the group consisting of the spacer body being integral with said first and second ends and the spacer body being coupled with said first and second ends. 20 4. The spacer element of any one of claims 1 to 3, wherein said spacer element is S C expandable from a substantially lay flat configuration to an elongate annular shaped spacer element.

5. The spacer element of any one of claims 1 to 4, wherein said unexpanded spacer element is in the form of a substantially lay flat configuration.

6. The spacer element of any one of claims 1 or 5 wherein the spacer element comprises a material selected from the group consisting of plastics, polyethylenes, and high quality coextruded polymeric materials and wherein said material is said spacer element is substantially impervious to gas.

7. The spacer element of any one of claims 1 to 6, wherein said spacer element further includes means for expanding said element with an expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, from a substantially lay flat configuration to an expanded spacer element. [R:\LIBH00384a.doc:LG

8. The spacer element of claim 7 wherein said means for expanding comprises means for providing an inflating substance said means for providing being located within said spacer element.

9. The spacer element of claim 7 wherein said means for expanding comprises means for providing an inflating substance located within said spacer element and is capable of being actuated by a user. The spacer element of claim 9 wherein said means for providing is selected from the group consisting of at least one aerosol canister including an inflating substance, at least one aerosol canister including an inflating substance and having delay means for delaying the release of the inflating substance on actuation of the canister so as to permit the unexpanded element to be located in a bore hole after actuation of the canister, at least one aerosol canister including an inflating substance and having slowing means for slowing the release of the inflating substance on actuation of the canister so as to permit the unexpanded element to be located in a bore hole after actuation of the canister, coreagent separation means having co-reacting reagents separated from one another which on mixing release an inflating substance said contaiment means capable of being actuated so as to allow mixing of said coreagents and coreagent separation means having co-reacting reagents separated from one another which on mixing release an inflating substance said separation means capable of being actuated so as to allow mixing of said 20 co-reagents said separation having delay means for delaying mixing of said co-reagents **S after being actuated so as to permit the unexpanded element to be located in a bore hole S S after actuation of the separation means. S-11. The spacer element of claim 7, wherein said means for expanding comprises means for providing an inflating substance said means for providing being located within said spacer element and further comprising delay means for delaying the inflation of the spacer element on actuation of the means for expanding said delay means being operatively associated with said spacer element.

12. The spacer element of claim 11, wherein said delay means is an outer material located about said spacer element which material fails once a certain pressure is reached inside said spacer element.

13. The spacer element of claim 7, wherein said means for expanding comprises means for providing an inflating substance said means for providing being located within said spacer element and further comprising slowing means for slowing the inflation of the spacer element on actuation of the means for expanding said slowing means being operatively associated with said spacer element. [R:\LIBH]00384a.doc:LJG

14. The spacer element of claim 13, wherein said slowing means is an outer material located about said spacer element which material slows the expansion of said element. The spacer element of any one of claims 1 to 6, wherein said spacer element further includes means through which expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, can be passed so as to expand said element from a substantially lay flat configuration to an expanded spacer element.

16. The spacer element of claim 15, wherein said means through which expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, can be passed so as to expand said element is a valve.

17. The spacer element of claim 15, wherein said means through which expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, can be passed so as to expand said element is a conduit.

18. The spacer element of any one of claims 1 to 17, wherein the shape of said spacer element when substantially fully expanded is that of an elongate substantially cylindrical member, such that the cross-sectional diameter of the expanded spacer element when inserted in a bore hole is less than the cross-sectional diameter of the bore hole so as to 20 permit explosive to be placed in the bore hole alongside and adjacent the spacer element.

19. A substantially fully expanded spacer element capable of insertion in a bore hole a wherein o the shape of the substantially fully expanded spacer element is such that when the spacer element is located in the bore hole the element can be positioned within the bore hole so as to permit explosive, optionally with fillers, to be placed in the bore hole adjacent the spacer element; and said spacer element is expanded with an expanding material less dense than the density of an explosive to be placed in the borehole adjacent the spacer element, optionally with fillers, whereby said overall density of said expanded spacer element is less than the density of said explosive, whereby the density of that part of the bore hole that comprises the expanded spacer element and the explosive adjacent the spacer element is less than what the density of said part of said bore hole would be if it were charged only with the explosive. The spacer element of claim 19 comprising a spacer body having a first end and a second end. [R:\LIBH]00384a.doc:LJG 46

21. The spacer element of claim 20, wherein said spacer body is linked to said first and second ends in a manner selected from the group consisting of the spacer body being integral with said first and second ends and the spacer body being coupled with said first and second ends.

22. The spacer element of any one of claims 19 or 21 wherein the spacer element comprises a material selected from the group consisting of plastics, polyethylenes, and high quality coextruded polymeric materials and wherein said material is said spacer element is substantially impervious to gas.

23. The spacer element of any one of claims 19 to 22, wherein the shape of said spacer element when substantially fully expanded is that of an elongate substantially cylindrical member, such that the cross-sectional diameter of the expanded spacer element when inserted in a bore hole is less than the cross-sectional diameter of the bore hole so as to permit explosive to be placed in the bore hole alongside and adjacent the spacer element.

24. A process for inserting an explosive and at least one expanded spacer element capable of insertion in a bore hole according to any one of claims 19 to 22, comprising the steps of: inserting into the bore hole said at least one expanded spacer element so as to permit the explosive to be placed in the borehole adjacent the spacer element; and 9999 inserting the explosive, optionally including fillers, in said bore hole adjacent said oo9* 20 expanded spacer element, said overall density of said expanded spacer element being less than the density of said explosive, whereby the density of that part of the borehole comprising the spacer element and the explosive adjacent the spacer element is less than *9 what the density of said part of said borehole would be if it were charged only with the explosive.

25. A process for inserting an explosive and at least one expandable spacer element 99 capable of insertion in a bore hole according to claim 1, comprising the steps of: 999• inserting into the bore hole said at least one spacer element; expanding the at least one spacer element in the borehole until the at least one spacer element is substantially fully expanded; locating the fully expanded element in the borehole so as to permit the explosive to be placed in the borehole adjacent the spacer element; and inserting the explosive, optionally including fillers, in said bore hole adjacent said expanded spacer element, said overall density of said expanded spacer element being less than the density of said explosive, whereby the density of that part of the borehole comprising the spacer element and the explosive adjacent the spacer element is less than [R:\LIBH]00384a.doc:LJG what the density of said part of said borehole would be if it were charged only with the explosive.

26. The process of claim 24 wherein step comprises: inserting into the bore hole said at least one expanded spacer element so as to permit the explosive to be placed in the borehole adjacent the spacer element, said spacer element having been expanded with an expanding material less dense than the density of said explosive, optionally with fillers.

27. The process of claim 24 wherein step comprises: inserting into the bore hole said at least one expanded spacer element so as to permit the explosive to be placed in the borehole adjacent the spacer element, said spacer element having been expanded with an expanding material less dense than the density of said explosive, optionally with fillers, said expanding material being selected from the group consisting of gas, foam, polystyrene.

28. The process of claim 25 wherein step comprises: expanding the at least one spacer element in the borehole with an expanding material less dense than the density of said explosive, optionally with fillers.

29. The process of claim 25 wherein step comprises: expanding the at least one spacer element in the borehole with an expanding .o material less dense than the density of said explosive, optionally with fillers, said expanding material being selected from the group consisting of gas, foam, polystyrene. The process of claim 24 or 25 wherein the borehole includes water therein and the process further comprises: dewatering the borehole prior to said inserting the explosive. The process of claim 24 or 25 further comprising: lining the borehole with a borehole liner prior to step The process of claim 24 or 25 further comprising: inserting a borehole plug in the borehole.

33. The process of claim 24 or 25 further comprising: inserting a borehole plug in the borehole prior to step to support a borehole liner; and lining the borehole with the borehole liner, prior to step

34. The process of claim 24 or 25 further comprising: inserting a borehole plug in the borehole prior to step to support a borehole liner; lining the borehole with the borehole liner prior to step and inserting a borehole plug to close the borehole after step

35. The process of claim 25 further comprising: inserting a borehole plug in the borehole prior to step to support a borehole liner; [R:\LIBH]00384a.doc:LJG 48 lining the borehole with the borehole liner prior to step and inserting a borehole plug to close the borehole after step

36. The process of claim 24 further comprising: detonating the explosive in the borehole after step

37. The process of claim 25 further comprising: detonating the explosive in the borehole after step

38. A process for inserting an explosive and at least one spacer element capable of insertion in a bore hole comprising the steps of: inserting into the bore hole said at least one spacer element wherein said spacer element is in a configuration selected from the group consisting of an unexpanded configuration and a partially expanded configuration, said bore hole being partially filled with water; partially filling the spacer element with a filler material having a density selected from the group consisting of filler material having substantially the same density as water and filler material having greater density than water to a level in the spacer element that is about level with the surface level of water in the bore hole; expanding the partially filled spacer element in the borehole until the spacer element is substantially fully expanded; locating the fully expanded element in the borehole so as to permit the explosive to be placed in the borehole adjacent the spacer element; and inserting the explosive, optionally including fillers, in said bore hole adjacent said Sexpanded spacer element, said overall density of said expanded spacer element being less than the density of said explosive whereby the density of that part of the borehole comprising the spacer element and the explosive adjacent the spacer element is less than what the density of said part of said borehole would be if it were charged only with the explosive. ~39. The process of claim 38 further comprising: detonating the explosive in the borehole after step .555

40. The process of claim 25 wherein said spacer element is in a configuration selected S S°30 from the group consisting of an unexpanded configuration and a partially expanded configuration. [R:\LIBH]00384a.doc: LJG 24 May 2000 i SE Minteeh-Pty td- -o Soothjet Pty Ltd Sanleo Holdings Pty Ltd Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON see* 096 0 [R:\LIBHIOO384a.doc: LG