Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt
  • C06B31/28—Compositions containing an inorganic nitrogen-oxygen salt the salt being ammonium nitrate
  • C06B31/30—Compositions containing an inorganic nitrogen-oxygen salt the salt being ammonium nitrate with vegetable matter; with resin; with rubber
• • 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
  • Y10S149/00—Explosive and thermic compositions or charges
  • Y10S149/11—Particle size of a component
• • 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
  • Y10S149/00—Explosive and thermic compositions or charges
  • Y10S149/11—Particle size of a component
  • Y10S149/112—Inorganic nitrogen-oxygen salt

Definitions

• the present invention relates to new or improved methods for the production of explosive compositions and blasting charges containing ammonium nitrate and carbonaceous ingredients,
• mixtures of ammonium nitrate and the vegetable cellular carbonaceous ingredients commonly used in explosives are generally more diflicult to initiate than the so-called permitted explosives.
• the sensitiveness to initiation of a mixture of a given carbonaceous ingredient with ammonium nitrate is relatively high when the composition of the mixture is highly oxygen-positive, and falls considerably as the proportion of the carbonaceous ingredient is increased up to and beyond the point at which the composition becomes oxygen-balanced.
• the presence of any of the flame-quenching ingredients used in permitted explosives also diminishes the sensitiveness.
• the ammonium nitrate explosives of commerce which are preferably approximately oxygen-balanced F and so modified as to be safe in'gassy atmospheres, contain a proportion of a nitric ester as sensitising ingredient.
• the low-density explosives are cartridged under a controlled pressure; so'that, when the mixture is filled into the usual paper containers, the various ingredients do not segregate during transport nor suffer inconvenient deformation while being handled and loaded into the bore hole.
• ordinary powder explosives are cartridged under various pressures such that-their bulk densities range from about 0.9 gram per 0. c. upwards, the lowdensity explosives are cartn'dged only under a gentle pressure, and are characterised by bulk densities lower than about 0.75 gram per 0. c.
• An object of the present invention is the manufacture of low-density explosive compositions ment.
• the present invention is based in part on the observation that, in the absence of self-explosive sensitlsers such as nitric esters, the bulk density of an ammonium nitrate mixture has a considerable eifect on its sensitiveness, which increases as the bulk density is reduced.
• the sensitiveness of the mixture is dependent on the nature of the carbonaceous ingredients, as well as on their in-- dividual bulk density.
• a lowdensity blasting explosive free from self-explosive sensltisers is manufactured by mixing ammonium nitrate in the presence of water with a carbonaceous material consisting of a low-density woodmeal or pithmeal having in the undisintegrated state a bulk density not exceeding 0.25 gram per 0. c., so that the ammonium nitrate is at least partly impregnated into the low density woodmeal or pithmeal; and the mixture, after being exposed to a raised temperature not exceedin 120 C. and evaporated till not more than about 2% moisture is present, is granulated so that the particles will pass through a sieve of about 6 mesh B.
• I may incorporate the woodmeal or pithmeal with a hot solution of the ammonium nitrate in only a small amount of water.
• the action of mixing at a high temperature greatly assists in the evaporation of the excess of water, and a special drying operation subsequent to the mixing is ofen unnecessary.
• I may conveniently pass it through the sieve while it has still a pasty consistency before it has cooled sufliciently for the mixture to form a hard cake.
• a large proportion of the material granulated in this manner has a grist corresponding to the sieve used.
• I may also allow the material to set, and then break up the cake mechanically, rejecting particles too large to pass through a 6 mesh B.S. sieve (apertures 0.11 inch square). If desired, however, a finer mesh sieve, e. g. a 12 mesh 3.8., may be used with advantage.
• the letters BS. denote an abbreviation for British Standard and apply to a standard basis for screens. These initials or letters are used in this sense throughout the present description.
• I may use, for instance, balsa wood, bongo wood, bagasse, megasse, or cornstalk pith.
• minor proportions of ingredients other than ammonium nitrate and low density woods or piths e. g. other carbonaceous materials, cooling or flame-quenching ingredients, oxidants, and inorganic fuels, may be included in the granulated mixture, according to the type of low-density explosive required.
• Such materials may be introduced after the granulation; in which case care should be taken that their particle size and/or amount is such that the voids between the granules are not filled.
• Some ingredients, especially those insoluble in water may be incorporated during the impregnation of the low-density material with the ammonium nitrate liquor.
• the granulated product produced according to my invention may have a lower bulk density than any of the ordinary low-density explosives, and owes its low density partly to the low density of the wood or pith, and partly to the operation of granulation.
• low-density mixtures produced by simple dry mixture of the same ingredients it maintains its low density and sensitiveness well when subjected to a slight degree of pressure such as is usually employed in cartridging low-density explosives. It also maintains its sensitiveness on transport and storage.
• the ratio of ammonium nitrate to low-density ingredient in the impregnated meal may conveniently be from 4.5/1 to 8.5/1; and the explosive may be oxygen-balanced.
• a 1 dia. x 3" cartridge of the above when initiated by a No. 6 :20 fulminate-chlorate detonator, transmits detonation to another similar cartridge at a separation not exceeding 1" (Ardeer double cartridge test).
• a file of 6 cartridges propagated throughout at a speed of 1700 metres per sec.
• Example 2 80 parts of ammonium nitrate, pulverised so that 80% of it passes a mesh 35. sieve, 10 parts of balsa meal and 2 parts of water are incorporated together in a jacketed mixer maintained at 100 C. until the mixture has attained a temperature of about 60 C. The mixture is sieved while still hot through a 12 mesh B.S. sieve, spread out, and allowed to cool. 50% of this product is held on a 16 BS. sieve, and not over 5% of it passes a 50 3.8. sieve. When cold, the mass is loaded at a light pressure of 20 lb. per square inch into paper shells to give cartridges at a bulk density of 0.55 gram per 0. c. A 1 dia. x 3" cartridge, when initiated by a No. 6 80:20 fulminate-chlorate detonator, detonates and transmits detonation to a similar cartridge at a separation not exceeding 1".
• Example 3 6.4 parts of an ammonium nitrate liquor, containing 96 parts ammonium nitrate and 4 parts water, are added at about C. to 1par't of a mixture of equal parts of balsa meal and megasse dust.
• the fibre is heated to 90 C. in a steamjacketed incorporator before the ammonium nitrate liquid is added, and the hot-mixing is continued until not more than 2% moisture remains in the mass.
• the mixture is then rubbed through a 6 BS. sieve, dried completely, and again sieved through a 6 BS. sieve.
• composition when cartridged under a pressure of 20 lb. per sq. inch, has a bulk density of 0.45 gram per 0. 0.; and when initiated by a No. 6 detonator as used in the previous examples, has a power equivalent to 75% of blasting gelatine, and a sensitiveness of inch.
• the velocity of detonation is 1780 metres/second.
• a method for producing a low density blasting explosive free from self-explosive sensitizers which comprises incorporating ammonium nitrate in the presence of water with a low density carbonaceous material having in the undisintegrated state a bulk density not exceeding 0.25 grams/co, drying the resultant mixture to a moisture content not exceeding 2%, and granulating to such fineness that all the particles pass through a 6-mesh screen and at least 50% are held on a 16-mesh screen.
• a method of producing a low density blasting explosive free from self-explosive sensitizers which comprises intermingling ammonium nitrate in the presence of water with a low density carbonaceous material having in the undisintegrated state a bulk density not exceeding 0.25 gram/cc., said intermingling being effected at an ture of ammonium nitrate and water, said inter-" mingling being efiected at a temperature not exceeding 120 0., cooling the-resultant mixture, then granulating to such'fineness that all the particles pass through a 6-mesh screen and at least 50% are held on a 16-mesh screen, and drying these particles to a moisture content not exceeding 2%.
• a blasting explosive composition capable of maintaining after packaging a bulk density below 0.75 gram/cc. and sensitive to initiation by a commercial detonator, said composition comprising granules consisting or low density carbonaceous material having in the undisintegrated state a bulk density not exceeding 0.25 gram/cc. impregnated with ammonium nitrate, said granules be- A ing of such size that all of them pass through. a 6-mesh screen and at least 50 are held on a 16- mesh screen.
• blasting composition of claim 4 wherein the blasting composition includes particles of flame-quenching ingredients, the particles being of such size that the voidsbetween the ammonium nitrate-carbonaceous material granules are not filled.
• a blasting explosive composition capable of maintaining after packaging a bulk density below 0.75 gram/cc. and sensitive to initiation by a commercial detonator, said. composition comprising granules consisting of low density carbonaceous material having in the undisintegrated state a bulk density not exceeding 0.25 gram/cc. impregnated with ammonium nitrate in amounts from 4.5 to 8.5 times the weight of the carbonaceous material, said granules being of such size that all of them pass through a i-mesh screen and at least 50% are held on a '16-mesh screen.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Organic Chemistry (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)
• Air Bags (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10395698

Family Applications (1)

Country Status (5)

Cited By (4)

Families Citing this family (1)

• 0
  • NL NL61260D patent/NL61260C/xx active
  • BE BE459232D patent/BE459232A/xx unknown
  • GB GB55989D patent/GB55989A/en not_active Expired
• 1938
  • 1938-12-22 GB GB37340/38A patent/GB522989A/en not_active Expired
• 1939
  • 1939-12-21 US US310439A patent/US2235060A/en not_active Expired - Lifetime
• 1945
  • 1945-08-28 FR FR917638D patent/FR917638A/fr not_active Expired

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