WO1998020296A1 - Stemming arrangement and method for blast holes - Google Patents
Stemming arrangement and method for blast holes Download PDFInfo
- Publication number
- WO1998020296A1 WO1998020296A1 PCT/GB1997/002892 GB9702892W WO9820296A1 WO 1998020296 A1 WO1998020296 A1 WO 1998020296A1 GB 9702892 W GB9702892 W GB 9702892W WO 9820296 A1 WO9820296 A1 WO 9820296A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- stemming
- hollow member
- explosive charge
- blast hole
- arrangement according
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 16
- 239000000463 material Substances 0.000 claims abstract description 77
- 239000002360 explosive Substances 0.000 claims abstract description 52
- 238000005474 detonation Methods 0.000 claims abstract description 35
- 229920003023 plastic Polymers 0.000 claims description 7
- 239000004033 plastic Substances 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 5
- 239000004698 Polyethylene Substances 0.000 claims description 2
- -1 polyethylene Polymers 0.000 claims description 2
- 229920000573 polyethylene Polymers 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 18
- 239000002245 particle Substances 0.000 description 8
- 238000010276 construction Methods 0.000 description 7
- 230000008901 benefit Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000010410 layer Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000011435 rock Substances 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- 230000003019 stabilising effect Effects 0.000 description 3
- 239000011800 void material Substances 0.000 description 3
- 238000005422 blasting Methods 0.000 description 2
- 239000002775 capsule Substances 0.000 description 2
- 238000005243 fluidization Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 229920001684 low density polyethylene Polymers 0.000 description 1
- 239000004702 low-density polyethylene Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
- E21B33/134—Bridging plugs
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
Definitions
- the present invention relates to a stemming arrangement and stemming method for use in blast holes having one or more explosive charges therein.
- blasting for example in mining, a number of blast holes are drilled and one or more explosive charges is placed at the end of the blast hole. Detonation of the explosive charges then ruptures the surrounding rock to enable it to be removed.
- Stemming of blast holes involves plugging the blast holes in order to avoid reduction in the effectiveness of the blasting operation caused by the escape of blast gases.
- Stemming has previously been carried out by simply filling the blast holes with suitable material, such as angular particles, which then resists escape of the blast gases because of the tendency of the particle of stemming material to lock together (so-called “bridging") to resist flow and because of the friction of the stemming material against the blast hole walls.
- stemming material can under certain circumstances still be ejected from the blast hole, for example, when the outward force of blast gases is so great that fluidising of the stemming material causes the stemming material to flow towards the mouth of the blast hole. This not only reduces the effectiveness of the blast, but the ejection of stemming material out of the blast hole can also be hazardous. In order to minimise this effect, the length of blast hole available and which can be effectively stemmed is sometimes insufficient to allow the use of the desired optimum size of explosive charge.
- US patent 4754705 discloses a mechanical stemming construction for blast holes in which a tapering wedge member is positioned in the blast hole outwardly of an explosive charge with its narrower end facing towards the mouth of the blast hole.
- a tapering wedge member is positioned in the blast hole outwardly of an explosive charge with its narrower end facing towards the mouth of the blast hole.
- particulate stemming material is loaded into the blast hole outwardly of the wedge member.
- Detonation of the explosive charge in the blast hole then causes the wedge member to be driven towards the mouth of the blast hole which in turn drives the wedge member into the stemming material .
- the outward movement of the wedge member compacts the stemming material causing the particles thereof to "bridge” and forces the stemming material laterally against the walls of the blast hole .
- a further disadvantage of this prior art stemming construction is that it generally requires the provision of a stabilising rod to correctly orient the wedge member in the blast hole.
- a protective layer of stemming material is located outwardly of the explosive charge to minimise the risk of the wedge member being destroyed by the initial detonation, and the wedge member is then located outwardly of the protective layer and with the appropriate orientation by means of the stabilising rod.
- the stabilising rod is then removed while the remainder of the blast hole is filled with stemming material. This procedure is often very difficult, if not impossible, to correctly achieve in the case of non vertical blast holes or blast holes of narrow diameter. In addition, mis-orientation of the wedge member can often occur after detonation.
- German Patent Application No 1287989 discloses an elastic spherical body which in use contains an air-water mixture under excess pressure.
- the body is located outwardly in a borehole of water-containing capsules, and is of a flexible nature having an unconfined diameter greater than that of the borehole.
- This prior art device is intended primarily to serve to assist in maintaining the water-containing capsules in place prior to detonation and is not intended to fulfil any stemming function after detonation. Accordingly, the extent to which this device can provide any effective post-detonation stemming is very limited.
- US Patent No 4913233 discloses an inflatable device for plugging a borehole to enable explosives to be located at a desired location in the borehole.
- the device is used to preserve an unfilled void in the borehole such that upon detonation, high pressure gases may flow and do work in the void, thereby reducing the total amount of explosive used and increasing the effective use of explosives. It is an essential requirement that this prior art device allows gas to flow to the void, as a result of which the device has insufficient strength to resist gas flow caused by detonation of an explosive charge.
- Preferred embodiments of the present invention seek to overcome the above disadvantages of the prior art.
- a stemming arrangement for a blast hole having at least one explosive charge therein comprising: at least one hollow member arranged in use in the blast hole outwardly of an associated explosive charge, wherein detonation of the associated explosive charge deforms the or each hollow member so as to substantially block the bore of the blast hole at the location of said hollow member to substantially impede outward passage of material past said hollow member, and the or each hollow member is made of sufficiently strong material to remain substantially functionally intact after detonation of the associated explosive charge.
- the or each hollow member has a respective internal surface substantially enclosing a respective internal space .
- substantially enclose encompasses one or more hollow members which do not entirely enclose the respective internal space, but allow air to pass from the interior of the hollow member to the exterior thereof on deformation of the hollow member as a result of detonation of the associated explosive charge .
- the or each hollow member may be substantially liquid tight .
- the or each hollow member is substantially spherical.
- the or each hollow member may comprise first and second cooperating substantially hemispherical portions.
- the or each hollow member is preferably at least partially filled with stemming material.
- the or each hollow member is at least partially filled with a stemming material comprising gravel .
- the or each hollow member preferably comprises plastics material .
- the plastics material may comprise polyethylene.
- the plastics material may comprise PET.
- the arrangement may further comprise a buffer layer of stemming material arranged between a said hollow member and the associated explosive charge.
- the arrangement preferably further comprises particulate stemming material arranged in the blast hole, at least part of the stemming material being arranged outwardly of the or each hollow member.
- the or each hollow member has a wall thickness between substantially 0.5% to 75% of the external diameter of said hollow member, and preferably between substantially 1% and 6% of the external diameter of said hollow member .
- a method of stemming a blast hole having at least one explosive charge therein comprising: locating at least one hollow member in the blast hole outwardly of an associated explosive charge, wherein detonation of the associated explosive charge deforms the or each hollow member so as to substantially block the bore of the blast hole at the location of said hollow member and substantially impede outward passage of material past said member, and the or each said hollow member made of sufficiently strong material to remain substantially functionally intact after detonation of the associated explosive charge.
- the method preferably further comprises the step of providing a buffer layer of stemming material between a said hollow member and the associated explosive charge.
- the method preferably further comprises the step of locating stemming material in the blast hole such that at least part of the stemming material is arranged outwardly of the or each hollow member.
- Figure 1 is a schematic elevation view of a stemming arrangement embodying the present invention
- Figure 2A shows the behaviour of the stemming arrangement of Figure 1 in the period immediately following detonation of an explosive charge
- Figure 2B shows the behaviour of a conventional borehole containing stemming material in the period immediately following detonation.
- a blast hole 1 is formed in a body of rock 2 by drilling and has an explosive charge 3 located at its innermost end. It will be appreciated by persons skilled in the art that the Figure shows an illustrative example only and that more than one explosive charge 3 may be located in the blast hole 1.
- a hollow generally spherical member 4 of plastics material is formed from a first generally hemispherical part 5 and a second generally hemispherical part 6 which are adapted to fit together such that the first part 5 overlies the second part 6 at an overlapping region 7.
- the spherical member 4 may be formed from any suitable liquid tight material capable of being deformed, rather than ruptured, by the force of blast gases generated by the detonation of the explosive charge 3. Hydrocode analysis shows that a material flow regime in which fluid flow is fastest at the axial centre of the blast hole 1 is substantially responsible for fluidisation of stemming material, which in turn prevents effective bridging of the particles of stemming material.
- a suitable material for constructing the spherical member 4 is therefore one having sufficient tensile strength to withstand the significant differential pressure across the blast hole radius associated with such a flow regime, and a typical material may be low density polyethylene or PET.
- typical wall thicknesses of the first 5 and second 6 parts of the spherical member 4 would be between 1mm and 10mm, typically 3 to 4mm.
- the spherical member 4 is filled with sand and/or gravel and the first 5 and second 6 parts are fitted together so that the hollow member 4 is substantially liquid tight.
- a buffer layer 8 of particulate stemming material is located outwardly of the explosive charge 3 and the spherical member 4 is then located outwardly of the buffer layer 8, either by being dropped down the vertical blast hole 1 shown in the Figure or, in the case of a non-vertical blast hole, by being placed by means of a suitable rod (not shown) .
- the buffer layer 8 will typically have a thickness of between one and ten blast hole radii so as to optimise the balance of the bridging effect in the stemming material above and below the spherical member 4.
- the spherical member 4 When the spherical member 4 has been located in position, the remainder of the bore of the blast hole 1 is filled with stemming material 10, which would preferably be a material comprising angular particles and therefore suitable for effective "bridging" .
- the spherical member 4 has a diameter slightly less than that of the blast hole 1, to enable suitable detonation wires (not shown) to extend along the blast hole 1 past the spherical member 4 to the ground surface 9.
- the detonation gases are either prevented altogether from passing the member 4 (which may be displaced a considerable distance towards the mouth 11 of the blast hole 1) , or to an insufficient extent to cause fluidisation of the stemming material 10 located outwardly of the member 4 which in turn prevents the stemming material 10 from being ejected from the blast hole 1.
- a stemming material close to the explosive charge on detonation receives a greater pressure impulse near the axial centre of the borehole 1 than at the edges.
- This drives the stemming material towards the spherical member 4 , which in turn prevents ejection of stemming material from the borehole by absorbing and equalising the pressure field across the borehole, and blocking high pressure gas permeation of the stemming material .
- the spherical member 4 thus flexes under explosive loading to create a frictional gas impermeable seal .
- the stemming material at the axial centre of the borehole 1 has a greater upward velocity, and one significant differential particle flow between the stemming material at the centre and the edge of the borehole as established, bridging of the stemming material becomes impossible and the stemming material is subsequently ejected from the borehole.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Geology (AREA)
- Fluid Mechanics (AREA)
- Environmental & Geological Engineering (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- Geochemistry & Mineralogy (AREA)
- Drilling And Exploitation, And Mining Machines And Methods (AREA)
- Excavating Of Shafts Or Tunnels (AREA)
- Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
Abstract
Description
Claims
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97909462A EP0934500B1 (en) | 1996-11-04 | 1997-10-21 | Stemming arrangement and method for blast holes |
AU47143/97A AU724035B2 (en) | 1996-11-04 | 1997-10-21 | Stemming arrangement and method for blast holes |
DE69713366T DE69713366T2 (en) | 1996-11-04 | 1997-10-21 | METHOD AND DEVICE FOR FILLING HOLES |
CA002270997A CA2270997A1 (en) | 1996-11-04 | 1997-10-21 | Stemming arrangement and method for blast holes |
AT97909462T ATE219237T1 (en) | 1996-11-04 | 1997-10-21 | METHOD AND DEVICE FOR FILLING BOREHOLES |
BR9712865-1A BR9712865A (en) | 1996-11-04 | 1997-10-21 | Filling arrangement and method for blast holes |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9622942.2A GB9622942D0 (en) | 1996-11-04 | 1996-11-04 | Stemming arrangement and method for blast holes |
GB9622942.2 | 1996-11-04 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/483,330 Continuation US6386111B1 (en) | 1996-11-04 | 2000-01-14 | Stemming arrangement and method for blast holes |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998020296A1 true WO1998020296A1 (en) | 1998-05-14 |
Family
ID=10802418
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1997/002892 WO1998020296A1 (en) | 1996-11-04 | 1997-10-21 | Stemming arrangement and method for blast holes |
Country Status (13)
Country | Link |
---|---|
US (1) | US6386111B1 (en) |
EP (1) | EP0934500B1 (en) |
AR (1) | AR010056A1 (en) |
AT (1) | ATE219237T1 (en) |
AU (1) | AU724035B2 (en) |
BR (1) | BR9712865A (en) |
CA (1) | CA2270997A1 (en) |
DE (1) | DE69713366T2 (en) |
ES (1) | ES2180028T3 (en) |
GB (1) | GB9622942D0 (en) |
PT (1) | PT934500E (en) |
WO (1) | WO1998020296A1 (en) |
ZA (1) | ZA979869B (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6631684B2 (en) * | 1999-09-16 | 2003-10-14 | Dae Woo Kang | Rock blasting method using air bladders embedded in loading layers |
AUPQ591000A0 (en) | 2000-02-29 | 2000-03-23 | Rockmin Pty Ltd | Cartridge shell and cartridge for blast holes and method of use |
AU2003200490B2 (en) * | 2002-02-20 | 2008-05-08 | Rocktek Ltd. | Apparatus and method for fracturing a hard material |
US20050066836A1 (en) * | 2003-09-12 | 2005-03-31 | Yigal Levi | Method for controlling explosions in open mines |
KR100680855B1 (en) * | 2005-03-11 | 2007-02-08 | 강대우 | Air tube for blasting and rock blasting method for using it |
CA2666645A1 (en) * | 2006-10-19 | 2008-08-21 | Carroll Bassett | Self-stemming cartridge |
WO2015068110A1 (en) * | 2013-11-05 | 2015-05-14 | Fowlds 3 Limited | A cartridge |
CN113357985B (en) * | 2021-05-28 | 2022-06-07 | 北京工业大学 | Spherical air charging spacer for blasting engineering and spaced charging method |
CN115183642B (en) * | 2022-07-19 | 2023-10-20 | 陕煤集团神木红柳林矿业有限公司 | Instantaneous spalling ware hole sealing device |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1287989B (en) * | 1964-07-10 | 1969-01-23 | Hoelter Heinz | Verdaemmungskoerper for holding water filling ampoules in boreholes |
US4660644A (en) * | 1986-01-31 | 1987-04-28 | Richard Egnor | Inflatable rubber blasting hole plug |
US4754705A (en) * | 1986-11-17 | 1988-07-05 | The Curators Of The University Of Missouri | Mechanical stemming construction for blast holes and method of use |
US4913233A (en) * | 1988-03-10 | 1990-04-03 | Fitzgibbon Jr Daniel F | Methods of field blasting of earth formations using inflatable devices for suspending explosives in boreholes |
US5000261A (en) * | 1990-01-24 | 1991-03-19 | Fitzgibbon Jr Daniel F | Inflatable devices for suspending explosives in boreholes |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4774888A (en) | 1985-09-03 | 1988-10-04 | Mobil Oil Corporation | In situ disposable gel canister |
US5035286A (en) * | 1988-03-10 | 1991-07-30 | Fitzgibbon Jr Daniel F | Methods and apparatus for field blasting of earth formations using inflatable devices for suspending explosives in boreholes |
US5497829A (en) | 1993-11-17 | 1996-03-12 | Foam Concepts, Inc. | Expansion foam borehole plug and method |
US5841060A (en) * | 1995-10-24 | 1998-11-24 | Skaggs; Roger Dean | Blast plug |
AUPN637795A0 (en) * | 1995-11-03 | 1995-11-30 | Ici Australia Operations Proprietary Limited | Method and apparatus for blasthole stemming |
-
1996
- 1996-11-04 GB GBGB9622942.2A patent/GB9622942D0/en active Pending
-
1997
- 1997-10-21 AT AT97909462T patent/ATE219237T1/en not_active IP Right Cessation
- 1997-10-21 CA CA002270997A patent/CA2270997A1/en not_active Abandoned
- 1997-10-21 DE DE69713366T patent/DE69713366T2/en not_active Expired - Fee Related
- 1997-10-21 PT PT97909462T patent/PT934500E/en unknown
- 1997-10-21 EP EP97909462A patent/EP0934500B1/en not_active Expired - Lifetime
- 1997-10-21 BR BR9712865-1A patent/BR9712865A/en not_active IP Right Cessation
- 1997-10-21 ES ES97909462T patent/ES2180028T3/en not_active Expired - Lifetime
- 1997-10-21 AU AU47143/97A patent/AU724035B2/en not_active Ceased
- 1997-10-21 WO PCT/GB1997/002892 patent/WO1998020296A1/en active IP Right Grant
- 1997-11-03 ZA ZA9709869A patent/ZA979869B/en unknown
- 1997-11-04 AR ARP970105147A patent/AR010056A1/en active IP Right Grant
-
2000
- 2000-01-14 US US09/483,330 patent/US6386111B1/en not_active Expired - Fee Related
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1287989B (en) * | 1964-07-10 | 1969-01-23 | Hoelter Heinz | Verdaemmungskoerper for holding water filling ampoules in boreholes |
US4660644A (en) * | 1986-01-31 | 1987-04-28 | Richard Egnor | Inflatable rubber blasting hole plug |
US4754705A (en) * | 1986-11-17 | 1988-07-05 | The Curators Of The University Of Missouri | Mechanical stemming construction for blast holes and method of use |
US4913233A (en) * | 1988-03-10 | 1990-04-03 | Fitzgibbon Jr Daniel F | Methods of field blasting of earth formations using inflatable devices for suspending explosives in boreholes |
US5000261A (en) * | 1990-01-24 | 1991-03-19 | Fitzgibbon Jr Daniel F | Inflatable devices for suspending explosives in boreholes |
Also Published As
Publication number | Publication date |
---|---|
ATE219237T1 (en) | 2002-06-15 |
AU724035B2 (en) | 2000-09-07 |
US6386111B1 (en) | 2002-05-14 |
DE69713366D1 (en) | 2002-07-18 |
PT934500E (en) | 2002-10-31 |
AU4714397A (en) | 1998-05-29 |
BR9712865A (en) | 1999-12-07 |
DE69713366T2 (en) | 2002-09-26 |
EP0934500A1 (en) | 1999-08-11 |
AR010056A1 (en) | 2000-05-17 |
ZA979869B (en) | 1998-06-25 |
CA2270997A1 (en) | 1998-05-14 |
EP0934500B1 (en) | 2002-06-12 |
ES2180028T3 (en) | 2003-02-01 |
GB9622942D0 (en) | 1997-01-08 |
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