AU2006200994A1 - Cartridge shell and cartridge for blast holes and method of use - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): ROCKTEK LTD Invention Title: CARTRIDGE SHELL AND CARTRIDGE FOR BLAST HOLES AND METHOD OF USE The following statement is a full description of this invention, including the best method of performing it known to me/us: -2- O Cartridge Shell and Cartridge for Blast Holes Sand Method of Use Field of the Invention oO The present invention relates to a cartridge shell and a corresponding cartridge for blast holes for the purpose of fracturing hard materials. The invention further relates to a Smethod for fracturing hard materials.

N Background of the Invention A typical cartridge shell for a blast hole is in the form of a cylindrical tube closed at both ends. Some cartridges may contain only an energetic substance while others may contain both an energetic substance and an initiator. The cartridge will be inserted to reside near the toe of a blast hole drilled or otherwise formed in a rock or other hard material to be fractured. The hole may then be stemmed with a particulate stemming material. When the energetic material in the cartridge is initiated there is a rapid generation of gas and thus a rapid build up of gas pressure near the toe of the hole. Provided that the gas generated is contained for a short period of time the resulting gas pressure may cause fractures to be propagated from the hole through the hard material.

The efficiency and effectiveness of this process is largely determined by factors such as the provision and quality of a gas seal formed on the side of the cartridge nearest the collar of the blast hole and the ability to hold the seal in position. Clearly if the seal is poor, gas will escape around the seal thereby reducing gas pressure as well as the rate of gas pressure increase. Further, the escaping gas has adverse effects in terms of ejecting stemming from the blast hole, generation of recoil and producing flyrock. However, even if the seal is one of high integrity, if the seal is not held firmly in place and is able to be pushed back toward the collar of the hole then the physical volume of the confined space within the hole in which the gas acts increases, thereby decreasing the gas pressure.

H:\inydcniMUWqapcificiowi\Rodtdc\P60159 Cuiridge Shll and Ctridge or Bha Hosdoc 8/03/06

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CN Summary of the Invention SAccording to a first aspect of the present invention there is provided a method of fracturing 00 a hard material comprising the steps of: providing a blast hole having a collar adjacent a free face of the hard material and a toe at the opposite end of the hole; providing a cartridge having a body containing a quantity of an energetic 0 material, the body having a first and second opposite ends, the second end being tapered to form a point or wedge-like member directed away from the first end; 0 inserting the cartridge into the blast hole such that the second end faces the collar of the blast hole; depositing a particulate stemming material into the blast hole; and detonating the energetic material.

The method may further comprise the step of mechanically holding the particulate stemming material in the blast hole.

The mechanically holding step may involve inserting a stemming bar into the blast hole such that one end of the stemming bar bears against the particulate stemming material and an opposite end of the stemming bar extends from the free face of the hard material, and mechanical holding the opposite end of the stemming bar.

The mechanically holding step may further comprise the step of forming one end of the stemming bar with a point or wedge-like member directed away from the opposite end of the stemming bar.

When the method is used in an underground mine having a wall in which the blast hole is formed and an opposite wall, the step of mechanically holding the stemming in the hole can include the step of operating a jack so that one end bears on the wall over the blast hole while an opposite end of the jack bears on the opposite wall.

*\Idmhab\K 'apecificomfs\Rodc\P I59 idge Shel and Calridge fr Bb Holdoc W3/06 SThe method may further comprise the step of injecting a volume of a liquid or gel into the C blast hole after insertion of the cartridge to fill any space between an outer surface of the cartridge and the blast hole and to provide a liquid or gel layer between the second end of the cartridge and the particulate stemming material.

00 oO In one embodiment of the method, the depositing step involves blowing the particulate stemming material into the blast hole.

C According to a second aspect of the present invention, there is provided a cartridge shell for use in fracturing hard materials, the shell comprising: C1 a body defining a volume for holding a quantity of an energetic material, the body having a first and second opposite ends, the second end being tapered to form a point or wedge-like member directed away from the first end; and a passageway that extends along the body from a region adjacent the second end toward the first end, the passageway for receiving an initiator lead.

In one embodiment the passageway is provided on an internal surface of the body.

The cartridge shell may further comprise an aperture at or near the second end through which the initiator lead passes.

The body may further include a line or zone of weakness adjacent to the first end.

The body may be provided with an opening at the first end, and the cartridge shell may further comprise a closure device for closing the opening.

In one embodiment, the interface between the body and the closure device defines the line or zone of weakness.

In one preferred embodiment, the closure device comprises a cap.

In one alternative embodiment, the passageway is provided on an outer surface of the H:\hydeob\Kascrificat io\Rod dctdck\ 159 Catdidge Shel and Canridge fo DI HoIs.doc 8/03/06 O body.

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SIn such an embodiment an aperture may be provided at the first end through which an initiator lead passes.

00 O The body may be provided with an opening at the first end, and the cartridge shell may further comprise a closure device for closing the opening, and the aperture is provided in the closure device.

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D 10 In one embodiment the second end is provided with two or more inclined surfaces that i converge toward each other in the direction of the first end to the second end.

In another embodiment the second end is in the form of conical frustum.

In one embodiment the cartridge shell further comprises: a primary shell portion defining a first portion of the body for holding a portion of the energetic material, the primary shell portion having first and second opposite ends, the second end of the primary shell defines the second end of the cartridge shell; and at least one secondary shell portion having a generally cylindrical body defining a further portion of body for holding a further portion of energetic material, a first end and a second opposite end, each of the one or more secondary shell portions being releasably connected in an end to end manner with one of the first end of the primary shell portion or an adjacent secondary shell portion, with the second end of a final secondary shell portion defines the first end of the cartridge shell, wherein each of the primary shell portion and at least one secondary shell portion is provided with a passageway that, when the primary shell portion and at least one secondary shell portion are connected in an end to end manner, define the passageway of the cartridge shell.

The or each at least one secondary shell portion may have a first engaging means at one end and a second complementary engaging means at a second opposite end wherein the first engaging means of a secondary shell portion can be releasably engaged with the H: emb\Kveis\cktdRckt\P60IS9 Catridge Shll and Cartrie ftr eBa Hos.doc 8/03/06 -6-

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O second engaging means of an adjacent secondary shell portion.

SThe second engaging means can be receivable within the first engaging means.

Furthermore, the first end of the primary shell portion may be provided with a first 00 engaging means for engaging the second engaging means of an adjacent secondary shell portion.

The generally cylindrical body of the at least one secondary shell portion can have a first outer diameter and the second engaging means is in the form of an axial extension having a second outer diameter smaller than the first outer diameter, and the first engaging means C is in the form of a recess for receiving the axial extension.

In one embodiment the first engaging means and the second engaging means are relatively configured to provide an interference fit therebetween.

In such an embodiment the second engaging means can be in the form of at least one protrusion provided on an outer surface of the axial extension. Alternatively or additionally, the second engaging means may be in the form of a plurality of protrusions provided on an outer surface of the axial extension, each of the protrusions being axially spaced apart with respect to one another.

Each of the protrusions can be arranged to extend circumferentially about the outer surface of the axial extension.

In one embodiment the first engaging means is in the form of at least one circumferential ridge provided on an internal surface of the recess. In such an embodiment the first engaging means can be in the form of a plurality of circumferential ridges provided on an internal surface of the recess, each of the circumferential ridges being axially spaced apart with respect to one another.

Each of the at least one protrusion in one of the at least one secondary shell portion may be seated adjacent a respective one of the at least one circumferential ridge of an adjacent H:\aydemb\ep\saifroUs\Roodtdd\P?6059 Cwidge Shell and CMuie fr BMt Hoedmc 8/03/06 -7- 0 primary shell portion or secondary shell portion respectively.

SIn one embodiment the at least one protrusion has a saw tooth-like profile.

0 5 In an alternative embodiment the first engaging means is in the form of an internal thread provided on an internal surface of the recess, and the second engaging means is in the form of an external thread provided on an outer surface of the axial extension such that the first engaging means is threadingly engageable with the second engaging means.

I 10 The cartridge shell may further comprise a closure disc for closing the each of first end of Sthe primary shell portion and the or each at least one secondary shell portion at respective locations inboard of the first ends of the primary shell portion and at least one secondary shell portion. Furthermore, the primary shell portion and each of the at least one secondary shell portion may have an annular seat at the respective locations inboard of the first ends of the primary shell portion and at least one secondary shell portion for seating a respective closure disc.

At least one second ridge may be provided on an internal surface of the recess, the at least one second ridge being axially spaced from the annular seat to hold the closure disc against the annular seat.

In one embodiment each closure disc is combustible. Alternatively or additionally, each closure disc is frangible.

The first end of the primary shell portion and each of the first and second ends of the at least one secondary shell portion can be provided with a flat portion to assist alignment of the passageways in each of the primary shell portion and at least one secondary shell portion.

According to a third aspect of the present invention there is provided a cartridge according to an embodiment the second aspect, and a quantity of an energetic material held within the body of the cartridge shell.

H:lydmb\Kpecilicatis\Rocdct\P60159 Cmuidge Shel and Cwide fr Bhn HoieLdoc 8/03/06 -8-

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Nc The energetic material may be a propellant.

SIn on embodiment an initiator is disposed within the body.

00 O The cartridge may further comprise an initiator lead connected at one end to the initiator and disposed within the passageway of the cartridge shell. The initiator can be a nonexplosive initiator.

I 10 In the embodiment in which the cartridge shell comprises a primary shell portion and at least one secondary shell portion, the quantity of energetic material held in each of the first portion of the body in the primary and the further portion of the body in each of the at least one secondary shell portion may be 10 gm or less.

According to a fourth aspect of the present invention, there is provided method of fracturing a hard material, comprising the steps of: providing a blast hole having a collar adjacent a free face of the hard material and a toe at the opposite end of the hole; providing a cartridge according to the third aspect of the present invention; inserting the cartridge into the blast hole such that the second end of the cartridge faces the collar of the blast hole; depositing a particulate stemming material into the blast hole; and detonating the energetic material.

The method may further comprise the step of mechanically holding the particulate stemming material in the blast hole.

The mechanically holding step may involve inserting a stemming bar into the blast hole such that one end of the stemming bar bears against the particulate stemming material and an opposite end of the stemming bar extends from the free face of the hard material, and mechanical holding the opposite end of the stemming bar.

H:aydib\Kap\fictions\RcktWd\P60159 Caridge Shefl and Cartridge for Ba HoLeadoc 8/03/06 -9- O The mechanically holding step may further comprise the step of forming one end of the 1 stemming bar with a point or wedge-like member directed away from the opposite end of Sthe stemming bar.

When the method is used in an underground mine having a wall in which the blast hole is formed and an opposite wall, the step of mechanically holding the stemming in the hole can include the step of operating a jack so that one end bears on the wall over the blast hole while an opposite end of the jack bears on the opposite wall.

The method may further comprise the step of injecting a volume of a liquid or gel into the blast hole after insertion of the cartridge to fill any space between an outer surface of the cartridge and the blast hole and to provide a liquid or gel layer between the second end of the cartridge and the particulate stemming material.

In one embodiment of the method, the depositing step involves blowing the particulate stemming material into the blast hole.

Brief Description of the Drawings In order that the invention may be more easily understood, embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded sectional view of a cartridge shell in accordance with the present invention; Figure 2 is a bottom view of an end cap incorporated in the cartridge shell; Figure 3 is a view of section A-A of Figure 1; Figure 4 is a view of section Pi-PI of Figure 1; Figure 5 is a view of section P 2

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2 of Figure 1; Figure 6 is a view of section PI-PI of a second embodiment of the cartridge shell; Figure 7 is a view of section P 2

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2 of the second embodiment of the H.\baydrb\Kep,\ ,ikicatw.\Rodte\F6OI59 -C cidge bU am Lamnnge lor um non.aoc wvuuo

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O cartridge shell; t C Figure 8 is a section view of an upper end of a third embodiment of the cartridge shell; Figure 9 is a section view of a bottom part of the cartridge shell of Figure 1 00 O 5 showing the layout of an initiator and initiator lead; Figure 10 is a section view of a fourth embodiment of the cartridge shell; Figure 11 is a section view of a bottom part of a fifth embodiment of the Scartridge shell; NC Figure 12 depicts one method of use of a cartridge made from a cartridge shell in accordance with embodiments of this invention; CN Figure 13 illustrates the second method of use of a cartridge incorporating the cartridge shell in accordance with embodiments of this invention; Figure 14 illustrates a further embodiment of a cartridge shell/cartridge; Figure 15 is a sectional exploded view of a secondary shell depicted as Figure 14; and, Figure 16 is a plan view of a closure disc incorporated in the shell/cartridge shown in Figures 14 and Detailed Description of the Preferred Embodiments Figures 1-5 depict a first embodiment of the cartridge shell 10. The cartridge shell comprises a main body 12 defining a volume 14 for holding an energetic material (not shown). The main body 12 has a first end 16 and an opposite second end 18. The first end 16 is generally planar and in effect forms a planar base for the cartridge shell 10. The second end 18 however is tapered to form a point or wedge-like member The tapering of the second end 18 is configured so that an area of the second end 18 measured in a plane transverse to a longitudinal axis of the main body 12 reduces in a direction from the first end 16 to the second end 18. Thus, with reference to Figures 4 and the area of the second end 18 in plane P 2 is reduced in comparison to the area measured in plane P 1 H:NhAydb\Ksqp\pecification\Rodd\P60I59 CrUldge ShdI nd Cidge for BhM HoICdoc 8/03/06 -11-

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c The second end 18 can take one of a number of different specific shapes. In Figures 1, 4 Sand 5 it is seen that the second 18 is in the form of two inclined surfaces 22 and 24 that Sconverge toward each other. However, in an alternative embodiment, the second end 18 00 can be in the form of a cone or conical frustum. This is depicted in Figures 6 and 7, which illustrate a transverse section of the second end 18 through planes P 1 and P 2 respectively.

In yet a further embodiment, which is depicted in Figure 8, the second end 18 is in the form of a chisel point. Of course other shapes are possible such as, but not limited to, C three, four or five sided prisms.

ND SIdeally the main body 12 and the second end 18 would be formed integrally and from a plastics material. However it is possible for the second end 18 to be made separately from the main body 12 and if so, the two components can then be attached together. The main body 12 will conveniently be in the form of a cylindrical tube as depicted in Figure 3 showing section A-A of Figure 1.

Main body 12 has an opening 26 at the first end to allow filling of the cartridge shell with an energetic material. A closure device, in the form of a cap 28, is provided for insertion into, and closure of, the opening 26. The cap 28 is press/interference fitted into the opening 26. This forms a line or zone of weakness at the first end 16.

An aperture 30 is formed centrally through the cap 28 to allow an initiator such as an electric match 32 (see Figure 9) to be pushed into the main body 12. A lead 34 from the match 32 passes through aperture 30 for coupling with an electric power source.

In an alternative embodiment depicted in Figure 10 the outer surface 36 of the cartridge shell 10 near the first end 16 is provided with a passageway or recess 38 for seating the initiator lead 34. The recess 38 includes a first length 40 provided on the main body 12 and a second length 42 provided in the cap 28. The cap 28 is orientated when inserted into the main body 12 so that the lengths 40 and 42 of the recess 38 are in alignment. When the electric match 32 is inserted through the aperture 30 the lead 34 can be seated in the recess 38 to provide it with some protection from accidental damage or cutting when the H:\IaAeb\cqep\ffcaions\Roctd\P60159 Caridg e Shel and Caridge for Ba Holmdoc S/03/06 -12- 0 cartridge shell 10 is inserted into a blast hole. In a further variation the length 40 of the CI recess 38 can be extended along the main body 12 to at least a point where the wedge-like Smember 20 commences.

00 0 5 In a further variation depicted in Figure 11, the aperture 30 is placed in the point or wedgelike member 20 rather than in cap 28. In this embodiment, the cartridge shell 10 can also be provided with an internal passageway 35 through which the lead 34 passes to deposit the initiator 32 near the first end 16 inside the main body 12.

0 10 Figure 12 illustrates one method of use of the cartridge shell 10. The volume 14 of the C cartridge shell 10 is filled with an energetic substance such as a propellant to form a cartridge 10c. The cartridge 10c is inserted into a blast hole 46 formed in hard material 47 with first end 16 first so that the first end 16 is adjacent a toe 48 of the hole. Accordingly the second end 18 faces or is directed toward a collar 50 of the hole. Next, a quantity of particulate stemming material 52 is placed in the hole 46. Typically, this will be done by blowing. The stemming material 52 is blown into the hole 46 to a level below the free face 54 of the hard material 47 in which the hole 46 is formed. The stemming 52 may then be mechanically held in the hole 46.

In the embodiment of Figure 12, the mechanical holding is achieved by inserting a stemming bar 56 into the hole 46 so that one end 58 of the stemming bar 56 rests on the stemming 52 and an opposite end 60 of the stemming bar extends from the free face 54. A cup 62 is placed over and cradles end 60. An opposite side of the cup 64 is formed with a planar base and supports an acrow prop 66. The acrow prop 66 is extended in length or otherwise jacked so that its opposite end 68 abuts a wall 69 disposed opposite the free face 54.

By connecting lead 34 with an electrical power source, the initiator 32 generates a high temperature flame to initiate the propellant or other energetic material within the cartridge 10c. The gas generated upon initiation initially bursts through the main body 12 about the line of weakness formed by the coupling of the cap 28 to the main body 12. The increase in gas pressure can tend to force the cartridge 10c toward the collar 50 of the hole 46. As H:\b\ydeK \.epeciicatiWons\R nk&\6159 Curmdge Shel ad C"*ide fo rL HokSdoc 8/03/06 -13- 0this occurs, the point or wedge-like member 20 acts on the stemming 52 to increase the C radial compressive force on the stemming material in an annular-like region between the peripheral of the second end 18 and the adjacent portion of the surface of hole 46 thereby Sincreasing the sealing effect of the stemming material 52. The stemming material 52 is prevented from blowing out of the hole 46 by action of the mechanical retention provided by the stemming bar 56 and acrow prop 66.

The sealing effect of the stemming material 52 is enhanced by forming the stemming material 52 from a mixture of a dry binding agent, fines, and coarse material. It has been N 10 found that fly ash is a particularly beneficial binding agent and the mixture containing fly Sash has a tendency to set when blown under pressure into the hole 46. The binding agent and fines comprises particulate solids of mesh size less than about 1mm. The coarse material within the stemming aggregate contains particles of mesh size up to about 6mm.

Binding agents other than fly ash can be used in the stemming material such as waste products from smelters, or fines containing cementitious material.

In an alternative method for stemming the hole 46, after the cartridge 10c has been inserted into the hole a volume of a liquid or gel 70 is inserted into the hole 46 to fill any space between the outer surface of the cartridge 10c and the surface of the hole 46 and provide a liquid or gel layer 72 between the particulate stemming material 52 and the cartridge The gel 70 assists in sealing the hole 46 to prevent the escape of gases upon initiation of the energetic material held within the cartridge 1Oc. In all other respects, the method depicted in Figure 13 is the same as that depicted in Figure 12.

The use of the stemming material 52 either by itself or in conjunction with the liquid/gel provides a seal of high integrity that substantially limits the escape of gas. The mechanical retention of the stemming by use, in these embodiments, of the stemming bar 56 and the acrow prop 66 prevents the stemming 52 being displaced toward the collar of the hole 50 thus maintaining relative constant the volume of the hole 46 within which the gas operates.

Figures 14 and 15 depict a cartridge shell 10 and corresponding cartridge 100c in H:\mydmb\Keeepifitios\Rodctk\P601S9 Caridge Sll and CuidC e for Bha HokaIoc 8/03/06 -14-

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O accordance with a further embodiment of the present invention. The cartridge 100c is in C effect a stackable cartridge comprising a cartridge shell 10 in substantial accordance with Sthat depicted in Figure 1, although with a body 12 of shorter length, and two secondary C cartridges 102a and 102b (hereinafter referred to in general as "secondary cartridges 102").

00oO Different embodiments of the cartridge 100c can include either a single secondary cartridge 102 or more than two secondary cartridges 102. The cartridge shell 10, when containing energetic material constitutes primary cartridge SEach secondary cartridge 102 contains a quantity of energetic material (not shown) and is NO 10 formed so as to be connectable in an end to end fashion with the first end 16 of the main body 12 and with each other. In this way, the total quantity of energetic material contained by the cartridge 100c can be varied by connecting one or more secondary cartridges 102 to the main body 12. This has substantial ramifications in terms of transportation and storage of energetic materials. For example, by forming the body 12 and the secondary cartridges 102 to contain no more than 10 gm of energetic material, a 50 gm cartridge can be constructed by connecting together a single body 12 and four secondary cartridges 102.

However the individual body 12 and cartridges 102 can be transported separately as gm cartridges" potentially under less stringent requirements than a single 50 gm cartridge under the UN Safety Classification regarding the transportation of such goods.

Each secondary cartridge 102 has a first engaging means 104 at one end and a second complimentary engaging means 106 at a second opposite end. This enables the first engaging means of one secondary cartridge engaging means 104 of secondary cartridge 102b) to engage with the second engaging means of an adjacent secondary cartridge second engaging means 106 of secondary or booster cartridge 102a).

Each secondary cartridge 102 has an outer shell 108 which includes a substantially cylindrical body 110 with the first engaging means 104 being in the form of an axial extension 112 at the first end of the secondary cartridge 102. The extension 112 is formed with an outer diameter less than the outer diameter of the cylindrical body 110. The second engaging means 106 is in the form of a recess 114 formed at an opposite end of the cylindrical body 110.

H:\hydmb\Kc,\qpeifiCMio\Rdac\FO59 Cmridge Shell WUl LMtISC IN rIM H0X00C

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(c The outer surface of the axial extension 112 is circumscribed by two axially spaced protrusions 116. The protrusions 116 have a saw tooth like profile, as can be seen most clearly in Figure 00 oO O The inside surface of each recess 114 is likewise circumscribed by two axially spaced apart ridges or ribs 118.

As is further apparent from Figure 15, the inner diameter of the recess 114 is greater than the inner diameter of the cylindrical body portion 110 of the cartridge shell 108 creating an NC annular seat 120 therebetween. The recess 114 is created by inserting a closure disc 122 into the end of the cartridge shell 108 to sit against the annular seat 120. A further ridge or rib 124 is formed about the inside surface of the recess 114 at locations spaced from the annular seat 120 by a distance approximately equal to the thickness of the periphery of the disc 122. Further, the ridge 124 and disc 122 are dimensionally related so that the ridge 124 sits behind the disc 122 and effectively holds the disc 124 against the seat 120. The disc 122 is made from a combustible material such as plastics, paper or cardboard.

When assembling the cartridge 100c, the shells 108 are held in a vertical disposition with axial extension 112 down, and energetic material poured in through recess 114 to maximum level up to the annular seat 120. The closure disc 122 is then inserted past ridges 118 and 124 to be held against the annular seat 120.

To connect two secondary cartridges 102 together, the axial extension 112 of one cartridge is pushed into the recess 124 of an adjacent cartridge. During this process, the protrusions 112 click past the ridges 118 until the forward end of the extension bears against the disc 120. In this position, the ridges 118 are effectively seated with a snap fit behind respective protrusions 116. The end most secondary cartridge 102b of the cartridge 100c is closed with an end cap 28 identical to that described in relation to Figures 1 and A longitudinal groove 126 is formed along the outside surface of cartridge 100c/shell having a separate length on each of cartridge shell 10 and shells 108 of secondary H:\bahydibTeq,\pefihcgio.\Ro L \P60159 Cridge Sheil d Catridge for Bbt Hokadoc 8/03/06 -16cartridges 102a and 102b. The groove 126 seats lead 34 provided with an electric match 32 which is inserted into the end cap 28. Prior to the insertion of the end cap 28, a hole is Spierced through the disc 122 in cartridge 102b through which the match 32 can be inserted.

00 In order to assist in the alignment of the separate lengths of groove 126 on both the cartridge shell 10 and shells 108, the outside surface of each extension 112 and the inside surface of each recess 114 is provided with a flat The flat is depicted as item 128 on the axial extensions 112 in Figure 14. Corresponding flats (not shown) are provided on the tC inside surface of each recess 114.

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In order to allow insertion of the closure disc 122 into the recess 114, the disc 122 is also provided with a flat 130.

To facilitate coupling of the primary cartridge 10c with the booster cartridge 102a, shell is also modified in comparison to that depicted in Figure 1 by the incorporation of a recess 114 to receive the extension 112 of secondary cartridge 102a. The recess 114 in the primary cartridge 10c is of the same form and configuration as that described and depicted in relation to the secondary cartridges 102 and is closed by a disc 122.

Now that embodiments of the present invention have been described in detail it will be apparent to those skilled in the relevant art that numerous modification and variations may be made without departing from the basic inventive concepts. For example in the method depicted by Figures 12 and 13, instead of mechanically holding the stemming 52 within the hole 56 by use of an acrow prop 66, different mechanical devices can be used such as for example, a weight or massive object, or placing say the bucket of an excavator over the collar 50. In a further variation, second end 18 of the cartridge shell 10 can be formed with a circumferential rebate 74 as depicted in Figure 14 for seating one end of a sleeve or tube 76. The tube 76 is filled with the stemming material 52. Tube 76 ideally would be made from a thin walled easily frangible and/or pliable material such as paper, thin plastics, rubber or cardboard. Indeed the cartridge shell 10 could also be made of such materials. In this event the tube 76 and/or shell 10 can be radially expanded to press against the wall of hole 46 and eliminate any free volume within the hole when subjected H hvdMb\Kewsa' c hc om OCktd 59 Cuidge Shll nd Clrid fr Bha Holmadoc 8/03/06 -17to axial compression forces provided by the acrow prop 66 or other mechanical retention t

C

device. End 58 of stemming bar 56 can be press fit into the opposite end of the tube 76 to allow one step insertion of the cartridge 1 Oc, stemming material 52 and stemming bar.

00 Also, end 58 of the stemming bar 56 can be formed with a point, taper or wedge-like member 78 as shown in phantom in Figures 12 and 13 to assist in the radial spreading and compaction of the stemming material 52 against the sides of the hole 46 thereby increasing the sealing effect.

010 With reference to the embodiment shown in Figures 14-16, as an alternative to the snap tC< type fit between the primary cartridge 1 Oc and secondary cartridges 102, other types of couplings can be used. For example, in the simplest form, the axial extension 112 and recesses 114 can be relatively configured to provide an interference fit. In other alternatives, complimentary screw threads can be formed on the outer surface of the extension 112 and the inner surface of the recess 114. In yet a further variation, a bayonet type coupling can be provided.

In addition, the closure discs 122 can be replaced by a frangible and/or combustible webs.

In addition, it is possible for the closure disc 122 or web to be placed at the end of shell 108 distant the axial extension 112. In order to then allow for engagement of an adjacent cartridge 102, the cartridges 102 will be filled with a quantity of energetic material less than their volume providing an air space to accommodate the inserted axial extension 112.

Also, in Figure 14, a single electric match 32 is shown at the end of lead 34 for insertion into the end cap 28. However, it is possible for multiple electric matches or other initiators to be incorporated. For example, one or more additional electric matches can be coupled with a lead 34 via branch leads and sandwiched between the closure disc 122 and axial extension 112 of adjacent coupled primary shell and secondary shell, or to adjacent coupled secondary shells.

All such modifications and variations are deemed to be within the scope of the present invention the nature of which is to be determined from the above description and the H:K\Ma' pccciatio \Rockt \P6059 Cartidge Shell ad Cartrige for NO Hokadoc 803/06 -18appended claims.

In the claims of this application and in the description of the invention, except where the context requires otherwise due to express language or necessary implication, the words "comprise" or variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

H:Iydamb\Kcq,'ificatutdck\p6o59 Cauidgc Shll ad CMUridge fbr Ba Holcdoc 8/03/06

Claims (39)

1. A method of fracturing a hard material comprising the steps of: providing a blast hole having a collar adjacent a free face of the hard material and a toe at the opposite end of the hole; providing a cartridge having a body containing a quantity of an energetic material, the body having a first and second opposite ends, the second end being tapered to form a point or wedge-like member directed away from the first end; Sinserting the cartridge into the blast hole such that the second end faces the 10 collar of the blast hole; Sdepositing a particulate stemming material into the blast hole; and detonating the energetic material.

2. A method as claimed in claim 1, further comprising the step of mechanically holding the particulate stemming material in the blast hole.

3. A method as claimed in claim 2, wherein the mechanically holding step involves inserting a stemming bar into the blast hole such that one end of the stemming bar bears against the particulate stemming material and an opposite end of the stemming bar extends from the free face of the hard material, and mechanical holding the opposite end of the stemming bar.

4. A method as claimed in claim 3, further comprising the step of forming one end of the stemming bar with a point or wedge-like member directed away from the opposite end of the stemming bar. A method as claimed in either claim 3 or 4, wherein when the method is used in an underground mine having a wall in which the blast hole is formed and an opposite wall, the step of mechanically holding the stemming in the hole includes the step of operating a jack so that one end bears on the wall over the blast hole while an opposite end of the jack bears on the opposite wall. H:\heb\eheeap~tmna\itnd ddnsRck\P60159 Carrid Shell and Catridge for Bom HolSdoc 8/03/06 O 6. A method as claimed in any one of claims 1 to 5, further comprising the C-i step of injecting a volume of a liquid or gel into the blast hole after insertion of the Scartridge to fill any space between an outer surface of the cartridge and the blast hole and to provide a liquid or gel layer between the second end of the cartridge and the particulate 00 stemming material.

7. A method as claimed in any one of claims 1 to 6, wherein the depositing step involves blowing the particulate stemming material into the blast hole. O I 10 8. A cartridge shell for use in fracturing hard materials, the shell comprising: Sa body defining a volume for holding a quantity of an energetic material, the body having a first and second opposite ends, the second end being tapered to form a point or wedge-like member directed away from the first end; and a passageway that extends along the body from a region adjacent the second end toward the first end, the passageway for receiving an initiator lead.

9. A cartridge shell as claimed in claim 8, wherein the passageway is provided on an internal surface of the body.

10. A cartridge shell as claimed in claim 9, further comprising an aperture at or near the second end through which the initiator lead passes.

11. A cartridge shell as claimed in either any one of claims 8 to 10, wherein the body includes a line or zone of weakness adjacent to the first end.

12. A cartridge shell as claimed in claim 11, wherein the body is provided with an opening at the first end, and the cartridge shell further comprises a closure device for closing the opening.

13. A cartridge shell as claimed in claim 12, wherein the interface between the body and the closure device defines the line or zone of weakness. H: %aynb\Kep\ ificatioa\Pz \P60159 Cmridge Sell and Cabidg e fist Bl HbIadOC S/03/06 -21-

014. A cartridge shell as claimed in either claim 12 or 13, wherein the closure C< device comprises a cap. A cartridge shell as claimed in claim 8, wherein the passageway is provided 00 on an outer surface of the body.

16. A cartridge shell as claimed in claim 15, further comprising an aperture at the first end through which an initiator lead passes. ND 10 17. A cartridge shell as claimed in claim 16, wherein the body is provided with an opening at the first end, and the cartridge shell further comprises a closure device for closing the opening, and the aperture is provided in the closure device.

18. A cartridge shell as claimed in any one of claims 8 to 17, wherein the second end is provided with two or more inclined surfaces that converge toward each other in the direction of the first end to the second end.

19. A cartridge shell as claimed in any one of claims 8 to 17, wherein the second end is in the form of conical frustum. A cartridge shell as claimed in any one of claims 8 to 19, wherein the cartridge shell further comprises: a primary shell portion defining a first portion of the body for holding a portion of the energetic material, the primary shell portion having first and second opposite ends, the second end of the primary shell defines the second end of the cartridge shell; and at least one secondary shell portion having a generally cylindrical body defining a further portion of body for holding a further portion of energetic material, a first end and a second opposite end, each of the one or more secondary shell portions being releasably connected in an end to end manner with one of the first end of the primary shell portion or an adjacent secondary shell portion, with the second end of a final secondary shell portion defines the first end of the cartridge shell, wherein each of the primary shell portion and at least one secondary shell H:\baydr\KccisptificaU,\B\ocktdc\P60159 Caridge Shel and Cmiige r Bls HoIdoc 8/03/06 -22- O portion is provided with a passageway that, when the primary shell portion and at least one Cl secondary shell portion are connected in an end to end manner, define the passageway of Sthe cartridge shell. 00

21. A cartridge shell as claimed in claim 20, wherein the or each at least one secondary shell portion has a first engaging means at one end and a second complementary engaging means at a second opposite end wherein the first engaging means of a secondary shell portion can be releasably engaged with the second engaging means of an adjacent 0 secondary shell portion. C' 22. A cartridge shell as claimed in claim 21, wherein the second engaging means is receivable within the first engaging means.

23. A cartridge shell as claimed in claim 22, wherein the first end of the primary shell portion is provided with a first engaging means for engaging the second engaging means of an adjacent secondary shell portion.

24. A cartridge shell as claimed claim 23, wherein the generally cylindrical body of the at least one secondary shell portion has a first outer diameter and the second engaging means is in the form of an axial extension having a second outer diameter smaller than the first outer diameter, and the first engaging means is in the form of a recess for receiving the axial extension. A cartridge shell as claimed in claim 24, wherein the first engaging means and the second engaging means are relatively configured to provide an interference fit therebetween.

26. A cartridge shell as claimed in claim 25, wherein the second engaging means is in the form of at least one protrusion provided on an outer surface of the axial extension.

27. A cartridge shell as claimed in claim 26, wherein the second engaging H:b\hayKcb\YAVicuif o\Rckt\P60159 Cadrige Shll ad Cauidg e or Bst Holmdoc 8/03/06 -23- Smeans is in the form of a plurality of protrusions provided on an outer surface of the axial CN extension, each of the protrusions being axially spaced apart with respect to one another.

28. A cartridge shell as claimed in either claim 26 or 27, wherein each of the 00 0 5 protrusions extend circumferentially about the outer surface of the axial extension.

29. A cartridge shell as claimed in any one of claims 24 to 28, wherein the first engaging means is in the form of at least one circumferential ridge provided on an internal Ssurface of the recess. C 30. A cartridge shell as claimed in claim 29, wherein the first engaging means is in the form of a plurality of circumferential ridges provided on an internal surface of the recess, each of the circumferential ridges being axially spaced apart with respect to one another.

31. A cartridge shell as claimed either claim 29 or 30, wherein each of the at least one protrusion in one of the at least one secondary shell portion can be seated adjacent a respective one of the at least one circumferential ridge of an adjacent primary shell portion or secondary shell portion respectively.

32. A cartridge shell as claimed in any one of claims 26 to 31, wherein the at least one protrusion has a saw tooth-like profile.

33. A cartridge shell as claimed in claim 21, wherein the first engaging means is in the form of an internal thread provided on an internal surface of the recess, and the second engaging means is in the form of an external thread provided on an outer surface of the axial extension such that the first engaging means is threadingly engageable with the second engaging means.

34. A cartridge shell as claimed in any one of claims 20 to 33, further comprising a closure disc for closing the each of first end of the primary shell portion and the or each at least one secondary shell portion at respective locations inboard of the first H:\baydenb\Kc lcci icatioi\Rodc\P60159 Cliide Shell and Crbide for Blat Hosdoc 8/03/06 -24- 0 ends of the primary shell portion and at least one secondary shell portion. A cartridge shell as claimed in claim 21, wherein the primary shell portion and each of the at least one secondary shell portion has an annular seat at the respective 00 locations inboard of the first ends of the primary shell portion and at least one secondary shell portion for seating a respective closure disc.

36. A cartridge shell as claimed in claim 35, wherein at least one second ridge NS is provided on an internal surface of the recess, the at least one second ridge being axially 0 10 spaced from the annular seat to hold the closure disc against the annular seat. 0

37. A cartridge shell as claimed in any one of claims 35 to 36, wherein each closure disc is combustible.

38. A cartridge shell as claimed in any one of claims 35 to 37, wherein each closure disc is frangible.

39. A cartridge shell as claimed in any one of claims 20 to 38, wherein the first end of the primary shell portion and each of the first and second ends of the at least one secondary shell portion are provided with a flat portion to assist alignment of the passageways in each of the primary shell portion and at least one secondary shell portion. A cartridge for use in fracturing a hard material, the cartridge comprising a cartridge shell as defined in any one of claims 8 to 19, and a quantity of an energetic material held within the body of the cartridge shell.

41. A cartridge for fracturing hard material, the cartridge comprising a cartridge shell as defined in any one of claims 20 to 39; and a quantity of energetic material held in each of the first portion of the body in the primary and the further portion of the body in each of the at least one secondary shell portion whereby, the total quantity of energetic material contained by the cartridge is varied by connecting one or more secondary shell portions to the primary shell portion. H:Iydenb\Kep\qlficmtons\Rodktek\P60159 Caidge Shel and Carbidg for Bas Hoiadoc 8/03/06 O S42. A cartridge as claimed in any either claim 40 or 41, wherein the energetic c material is a propellant. 00

43. A cartridge as claimed in any one of claims 40 to 42, further comprising an initiator disposed within the body.

44. A cartridge as claimed in claim 43, further comprising an initiator lead Sconnected at one end to the initiator and disposed within the passageway of the cartridge shell. A cartridge as claimed in any either claim 43 or 44, wherein the initiator is a non-explosive initiator.

46. A cartridge as claimed in any one of claims 43 to 45, further comprising a booster cartridge for the initiator.

47. A cartridge as claimed in any one of claims 40 to 46, wherein the quantity of energetic material held in each of the first portion of the body in the primary and the further portion of the body in each of the at least one secondary shell portion is 10 gm or less.

48. A method of fracturing a hard material, comprising the steps of: providing a blast hole having a collar adjacent a free face of the hard material and a toe at the opposite end of the hole; providing a cartridge as defined in any one of claims 40 to 47; inserting the cartridge into the blast hole such that the second end of the cartridge faces the collar of the blast hole; depositing a particulate stemming material into the blast hole; and detonating the energetic material.

49. A method as claimed in claim 48, further comprising the step of H:\Kvdecw\.ewDlocificuoim\Rdckte\P60159 Cinuide Shel and Cwthidne for Bho HokLdoc 8/03/06 -26- 0 mechanically holding the particulate stemming material in the blast hole. A method as claimed in claim 49, wherein mechanically holding step involves inserting a stemming bar into the blast hole such that one end of the stemming bar oO O 5 bears against the particulate stemming material and an opposite end of the stemming bar extends from the free face of the hard material and, mechanical holding the opposite end of the stemming bar. S51. A method as claimed in claim 50, further comprising the step of forming one end of the stemming bar with a point or wedge-like member directed away from the Ci opposite end of the stemming bar.

52. A method as claimed in either claim 50 or 51, wherein when the method is used in an underground mine having a wall in which the blast hole is formed and an opposite wall, the step of mechanically holding the stemming in the hole includes the step of operating a jack so that one end bears on the wall over the blast hole while an opposite end of the jack bears on the opposite wall.

53. A method as claimed in any one of claims 48 to 52, further comprising the step of injecting a volume of a liquid or gel into the blast hole after insertion of the cartridge to fill any space between an outer surface of the cartridge and the blast hole and to provide a liquid or gel layer between the second end of the cartridge and the particulate stemming material.

54. A method as claimed in any one of claims 48 to 53, wherein the depositing step involves blowing the particulate stemming material into the blast hole. H:\hydeb\Ke,\specificatiiu\Roitk\P60159 Caruidg Shel and Catidge fr BIa HOles.doc 8/03/06