US3610150A - Blasting method - Google Patents

Blasting method Download PDF

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Publication number
US3610150A
US3610150A US785704A US3610150DA US3610150A US 3610150 A US3610150 A US 3610150A US 785704 A US785704 A US 785704A US 3610150D A US3610150D A US 3610150DA US 3610150 A US3610150 A US 3610150A
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United States
Prior art keywords
explosive
charge
powdered metal
column
blasting
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Expired - Lifetime
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US785704A
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English (en)
Inventor
Gordon Alger Teichmann
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Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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Publication of US3610150A publication Critical patent/US3610150A/en
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    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/04—Arrangements for ignition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S102/00—Ammunition and explosives
    • Y10S102/705—Separated explosive constituents

Definitions

  • Auxiliary explosive charge may be used to mix [52] 11.5.0 102/23, the ingredients of a shothole charge. Detonating fuse cord l02/24R may thus be used to distribute fuel oil through ammonium [51] Int.” "M 1/00 nitrate which is loaded separately intothe shothole.
  • blasting explosives based on ammonium nitrate.
  • these include, for example, ammonium explosives sensitized by nitroglycerine or trinitrotoluene, the so-called ANFO explosives, which are mixtures of ammonium nitrate and fuel oil, and slurried explosives which comprise ammonium nitrate and water.
  • ANFO explosives which are mixtures of ammonium nitrate and fuel oil
  • slurried explosives which comprise ammonium nitrate and water.
  • powdered metal for example aluminum, magnesium, iron, silicon or boron.
  • compositions are, however, thereby rendered less safe from premature initiation caused by accidental impact or friction or by chemical attack on the sensitizing ingredient.
  • a column of powdered metal surrounding a charge of high explosive having a higher velocity of detonation than the main charge and sufficient to disperse the powdered metal and detonating both explosive charges.
  • part, at least, of the powdered metal is dispersed and oxidized in the after detonation gases with consequent increase in the heat of explosion and I the gas presure.
  • From one aspect invention consists in a method of blasting wherein a column of a main charge of blasting explosive, a
  • the explosive charges may be detonated in known manner using, for example, end or intermediate priming or a combination of both fonns of priming.
  • the invention consists in an explosive charge assembly for blasting which comprises a column of a main explosive charge, a column of powdered metal in contact with the said main charge and, disposed within the column of powdered metal, an auxiliary charge of explosive of higher velocity of detonation than the main charge and sufficient to disperse the column of powdered metal.
  • the invention also includes an explosive accessory for use in the blasting method and the explosive charge assembly of the invention, which comprises a packaged column of powdered metal surrounding a charge of explosive having a high velocity of detonation and capable of dispersing the powdered metal.
  • the powdered metal is conveniently packaged in a container, for example, of synthetic plastics film such as polyethylene or polyvinyl chloride.
  • the beneficial effects of the invention may be achieved using any kind of blasting explosive, but the effect is most marked with relatively insensitive explosives, for example ANFO explosives and 'slurried explosives.
  • the main explosive charge is disposed as an annular column around the column of powdered metal and it is also preferable for the auxiliary explosive to be an elongated charge surrounded along its length by the powdered metal.
  • the preferred arrangement is one in which the explosive charges and the column of powdered metal are coaxial.
  • An especially convenient auxiliary charge comprises detonating fuse cord which may also be used to prime the maincharge. If desired, additional priming charges may be attached at the end or at intermediate positions on the detonating fuse cord.
  • a suitable fuse cord is one containing 20-100 grains of pentaerythritol tetranitrate (PETN) per foot.
  • a preferred method of blasting in accordance with the invention comprises disposing lengthwise in a shothole a length of detonating fuse cord surrounded along at least part of its length with a column of powdered metal contained in a thinwalled, tubular container, loading a charge of ANFO or slurried explosive around the powdered metal in theshothole and detonating the detonating fuse cord and the explosive charge.
  • a further advantage which is realized is that an insensitive explosive main charge composition is protected from becoming partially desensitized by compression on detonation of an adjacent detonating fuse cord charge which is lllillfl h cient to initiate the main charge to detonation, as may happen when a length of detonating fuse cord is used to communicate detonation to a primer at the bottom of a relatively insensitive main charge at the bottom of a shothole.
  • the powdered metal may comprise, for example, aluminum magnesium, iron, silicon or boron. It may. conveniently be in dry powder from or in suspension in a liquid, for example water, the suspension being easier to fill into plastics tubing and giving apparently superior blasting performance when used with ANFO explosive.
  • the suspending liquid may advantageously be thickened by dissolving therein a thickener, for example guar gum, ground psyllium seed or water-soluble cellulose ether.
  • the preferred metal powder is granular aluminum of particle size such that substantially all passes a 8.8. l0 mesh-sieve and at least 50 percent is retained on a 8.8. 30-mesh sieve.
  • FIG. 1 shows diagrammatically a sectional elevation of an explosive charge assembly loaded in a vertical shothole
  • FIG. 2 shows a cross section of the loaded shothole on the line "-11 of FIG. 1.
  • the shothole 10 contains a priming charge of high explosive l l at the bottom and a centrally disposed explosive accessory charge, consisting of a length of commercial detonating fuse cord 12 (Cordtex -Registered Trade Mark) and a surrounding layer of powdered metal 13 contained in a polythene tube 14.
  • One end of the cord 12 is attached to the charge II and the other end extends beyond the top of the shothole and has attached to it a detonator 15 by which it may be initiated.
  • a main charge 16 of powdered explosive is loaded by pouring it around the polythene tube 14 and is covered by stemming 17.
  • the priming charge 11 and the main charge 16 are detonated and the powdered metal 13 is dispersed and oxidized in the gases formed in the detonation.
  • EXAMPLE I Ten blasting explosive charges were tired in a limestone quarry bench blast in shotholes 4 pounds Inches in dhlneter and 60 feet deep, spaced at l2-feet intervals with a burden of 12 feet. Five adjacent holes at one side of the bench were loaded in accordance with the invention, as illustrated.
  • the priming charge II in each shothole was a 40 pounds base charge of a nitroglycerine gelatinous explosive sold commercially by Imperial Chemical Industries Llmited as Togel' (Registered Trade Mark) which filled the bottom 10 feet of the shothole.
  • the detonating fuse cord 12 was Cordtex fuse cord containing 50 grains of PETN per foot.
  • the powdered material 13 was granular aluminum powder, of particle size such that substantially all passed a 8.8.
  • l6-mesh sieve and 60 percent was retained on a BS. 30-mesh sieve, contained in a %-inch diameter polythene tube at a loading density of 0.23 pound/foot.
  • the main charge 16 was pounds of an ANFO mixture consisting of 94 percent ammonium nitrate and 6 percent of diesel oil, which was poured around the Togel and the aluminum charge 13, filling the shothole to a height of 30 feet The shothole was stemmed with quarry grit stemming 17 to the top. The remaining five adjacent holes were similarly charged except that'the aluminum powder charge 13 and the detonating fuse cord 12 were omitted and the priming charge was fired by an electric detonator.
  • EXAMPLE 2 Ten blasting charges were prepared and fired by the method of the invention in the same manner as described for the first five shotholes in example I, except that the main charge 16 was a charge of slurried composition consisting of 87 percent ammonium nitrate, l2 percent of water and 1 percent of guar gum, which was not sufficiently sensitive to propagate detonation in a 4-inch diameter shothole.
  • the blast gave better rock fragmentation and rock throw than was obtained from a similar blast from which the aluminum powder was omitted.
  • EXAMPLE 3 In this example the detonating fuse cord 12 (Cordtex) Cordtex) and the surrounding column of aluminum powder 13 were the same as those used in example 1 except that they were assembled from smaller units. Each unit consisted of a 6- foot length of Cordtex' surrounded by a 4% foot length of aluminum powder contained in polythene tubing 14 which was sealed by tying the ends tightly around the CordtexCordtex fuse cord Twelve units were joined together by tying the bare end portions of the Cordtex fuse cord together and covering the knots with adhesive tape.
  • l charges were fired in a quarry bench blast in shotholes 4 inches in diameter and 70 feet deep, spaced at 15 feet intervals with a burden of l 1 feet.
  • the holes were loaded as illustrated in the accompanying drawings, the priming charge being a l0 pound cartridge of Togel explosive.
  • the assembled units of aluminum powder and 'Cordtex fuse cord extended 60 feet from the bottom of the hole and a further length of Cordtex fuse cord attached to the fuse cord of the uppennost unit was led from the top of each shothole.
  • the main charge 16 was 240 pound of an ANFO mixture as used in example 1.
  • the top 10 feet of each shothole were stemmed with quarry grit stemming 17.
  • EXAMPLE 4 with a spacing of 10 feet and a burden of 10 feet. Seven adv jacent holes at one side of the bench were loaded in accordance with the invention as illustrated in the accompanying drawing.
  • the primer 1] in each shothole was a 10 pound cartridge of 'Togel' explosive and the main charge 16 in each shothole was 120 pound of ANFO explosive as used in example l, which filled the shothole to a depth of 33 feet.
  • the remaining 8 feet of each shothole were filled with quarry grit stemming 17.
  • the remaining 7 shotholes were charged in the same manner except that the aluminum powder 13 was omitted.
  • EXAMPLE 5 The blast of example I was repeated except that the column of aluminum powder 13 in each shothole loaded in accordance with the invention was in the form of an extrudable aqueous suspension consisting of 40 parts of aluminum suspended in 60 parts of water containing 2 percent of guar gum.
  • EXAMPLE 7 The blast of example 1 was repeated except that powdered silicon was charge instead of powdered aluminum. The results obtained were the same as those obtained in example I.
  • a method of blasting comprising: loading into a shothole a column of a main charge of blasting explosive, a column of powdered metal and an auxiliary charge of explosive having a higher velocity of detonation than the main charge, the auxiliary charge being surrounded by the column of powdered metal and being in sufficient amount to disperse at least part of the powdered metal in the after-detonation gases of the main charge; and detonating the charges.
  • a method as claimed in claim 1 wherein the main charge of blasting explosive is selected from the group consisting of an ANFO explosive and a slurried explosive.
  • auxiliary explosive charge is an elongated explosive charge.
  • auxiliary charge comprises a detonating fuse cord.
  • powdered metal is selected from the group consisting of powdered aluminum magnesium, iron, silicon and boron.
  • a method as claimed in claim 1 which comprises disposing lengthwise in a shothole a length of detonating fuse cord surrounded along at least part of its length with a column of powdered metal contained in a thin-walled container, loading a charge selected from the group consisting of ANFO and slurried explosive around the powdered metal in the shothole and detonating the detonating fuse cord and the explosive charge.
  • plastics film is selected from the group consisting of polyethylene and polyvinyl chloride.
  • An explosive charge comprising a column of a main charge of blasting explosive, a column of powdered metal and, surrounded by the column of powdered metal, an auxiliary charge of explosive of higher velocity of detonation than the main charge and in sufficient amount to disperse at least part of the column of powdered metal in the after-detonation gases of the main charge.
  • An explosive charge assembly as claimed in claim 14 wherein the platic is selected from the group consisting of polyethylene and polyvinyl chloride.
  • An explosive accessory for use in blasting comprising a column of powdered metal packed in a container and, surrounded by said column, a charge of explosive having a higher velocity of detonation than ANFO and in sufficient amount to disperse at least part of the powdered metal in the afterdetonation gases of an explosive charge detonated in contact with the accessory.
  • An explosive accessory as claimed in claim 28 wherein the powdered metal is selected from the group consisting of aluminum magnesium, iron, silicon, and boron.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
  • Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
  • Steam Or Hot-Water Central Heating Systems (AREA)
US785704A 1968-01-01 1968-12-20 Blasting method Expired - Lifetime US3610150A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB118/68A GB1195461A (en) 1968-01-01 1968-01-01 Blasting Method and Devices therefor

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US3610150A true US3610150A (en) 1971-10-05

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US (1) US3610150A (en))
BE (1) BE726205A (en))
DE (1) DE1900146A1 (en))
FR (1) FR1600596A (en))
GB (1) GB1195461A (en))
NO (1) NO119718B (en))

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3768411A (en) * 1971-11-29 1973-10-30 Explosives Corp America Safety blasting apparatus and method
US3968723A (en) * 1975-03-03 1976-07-13 The United States Of America As Represented By The Secretary Of The Navy Method for reclaiming and recycling plastic bonded energetic material
US4716967A (en) * 1985-05-13 1988-01-05 Mohaupt Henry H Stimulating subterranean formations in the open hole
US6539870B1 (en) * 2000-11-22 2003-04-01 Dyno Nobel Inc. Blasting method for reducing nitrogen oxide fumes
CN101521365B (zh) * 2008-11-28 2011-01-26 北京理工大学 一种冲击波去除输电线覆冰方法
RU2449241C1 (ru) * 2010-10-25 2012-04-27 Государственное образовательное учреждение высшего профессионального образования Читинский государственный университет (ЧитГУ) Способ формирования комбинированного заряда в обводненных скважинах
CN103398638A (zh) * 2013-08-08 2013-11-20 贵州新联爆破工程集团有限公司 一种爆破孔内炸药殉爆距离测定方法
CN104964620A (zh) * 2015-05-27 2015-10-07 中钢集团马鞍山矿山研究院有限公司 一种有效降低炮烟危害的爆破方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8719846D0 (en) * 1987-08-21 1987-09-30 Ici Plc Shaped primer
CN111397455A (zh) * 2020-04-15 2020-07-10 辽宁科技大学 一种隧道掘进中精确控制爆破效果的组合起爆方法
CN114440718B (zh) * 2022-01-06 2024-04-19 淮北矿业股份有限公司 基于液体炸药的深孔爆破残爆处理方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3046889A (en) * 1957-02-27 1962-07-31 Shell Oil Co Seismic exploration
US3094069A (en) * 1959-01-05 1963-06-18 Dow Chemical Co Method of blasting and ammonium nitrate explosive composition
US3112701A (en) * 1960-08-11 1963-12-03 Dow Chemical Co Disc for upgrading work of explosives
US3119332A (en) * 1960-09-06 1964-01-28 Dow Chemical Co Explosive compositions having upgraded power factors

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3046889A (en) * 1957-02-27 1962-07-31 Shell Oil Co Seismic exploration
US3094069A (en) * 1959-01-05 1963-06-18 Dow Chemical Co Method of blasting and ammonium nitrate explosive composition
US3112701A (en) * 1960-08-11 1963-12-03 Dow Chemical Co Disc for upgrading work of explosives
US3119332A (en) * 1960-09-06 1964-01-28 Dow Chemical Co Explosive compositions having upgraded power factors

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3768411A (en) * 1971-11-29 1973-10-30 Explosives Corp America Safety blasting apparatus and method
US3968723A (en) * 1975-03-03 1976-07-13 The United States Of America As Represented By The Secretary Of The Navy Method for reclaiming and recycling plastic bonded energetic material
US4716967A (en) * 1985-05-13 1988-01-05 Mohaupt Henry H Stimulating subterranean formations in the open hole
US6539870B1 (en) * 2000-11-22 2003-04-01 Dyno Nobel Inc. Blasting method for reducing nitrogen oxide fumes
CN101521365B (zh) * 2008-11-28 2011-01-26 北京理工大学 一种冲击波去除输电线覆冰方法
RU2449241C1 (ru) * 2010-10-25 2012-04-27 Государственное образовательное учреждение высшего профессионального образования Читинский государственный университет (ЧитГУ) Способ формирования комбинированного заряда в обводненных скважинах
CN103398638A (zh) * 2013-08-08 2013-11-20 贵州新联爆破工程集团有限公司 一种爆破孔内炸药殉爆距离测定方法
CN104964620A (zh) * 2015-05-27 2015-10-07 中钢集团马鞍山矿山研究院有限公司 一种有效降低炮烟危害的爆破方法

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Publication number Publication date
FR1600596A (en)) 1970-07-27
DE1900146A1 (de) 1969-09-25
BE726205A (en)) 1969-06-27
NO119718B (en)) 1970-06-22
GB1195461A (en) 1970-06-17

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