Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
  • C06C5/00—Fuses, e.g. fuse cords
  • C06C5/06—Fuse igniting means; Fuse connectors
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P35/00—Antineoplastic agents
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
  • C06B21/0033—Shaping the mixture
  • C06B21/0066—Shaping the mixture by granulation, e.g. flaking
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B33/00—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide

Definitions

• THIS INVENTION relates to the production of a pyrotechnic delay composition of the type used, for example, in delay elements employed for the delayed initiation of explosives. More particularly, the invention relates to a process for the production of such composition, and to a pyrotechnic delay composition.
• a process for producing a pyrotechnic delay composition including
• the pyrotechnic delay composition when used in the manufacture of delay elements employed for the delayed initiation of explosives, provides the delay elements with a desired burning rate.
• the liquid may be an organic liquid such as a solvent. Instead the liquid may be water.
• oxidizer and fuel constituents are selected in accordance with practical and economic considerations, bearing in mind safety and the intended use of the delay compositions.
• the oxidizer may be in solid particulate form.
• the oxidizer may comprise red lead, barium sulphate and/or potassium perchlorate.
• the oxidizer may comprise 40-90% by mass of the composition.
• the fuel may also be in solid particulate form.
• the fuel may comprise silicon, zinc and/or magnesium.
• the fuel may comprise 5-60% by mass of the composition.
• the surfactant or surface active agent may be in particulate form, and may be a wetting agent and/or a rheology modifier and/or a binder (binding agent).
• the surfactant may be selected from the so-called non-ionic surfactants, anionic surfactants and cationic surfactants.
• the surfactant may thus comprise an acrylic ester, a styrene polymer, and/or an acylic copolymer, which are all wetting agents; and/or a polyethelene glycol, a powdered smectite clay, carboxymethyl cellulose, polyvinyl alcohol and/or polyvinyl pyrrolidone which are rheology modifiers or thickeners.
• the surfactant may be in the form of an aqueous dispersion when admixed with the oxidizer and the fuel.
• the surfactant may comprise 0.25% to 4%, by mass, of the paste or slurry before drying, i.e. on a wet basis.
• the surfactant may comprise 0.1% to 2%, by mass, of the paste or slurry.
• At least one of the surfactants used may function, in the paste or slurry, as a rheology modifier such as a thickening agent.
• a rheology modifier such as a thickening agent.
• Such rheology modifiers will typically be selected for their ability, not only to alter or modify the burning rate of delay elements made from the delay compositions in question, but also to resist so-called sedimentation or separation of the constituents of the paste or slurry, after formulation thereof and before the drying.
• the surfactant may comprise 0.1-2% by mass of the composition.
• the composition may comprise
• the mixing of the constituents to formulate the paste or slurry will be carried out in a more or less conventional manner, using conventional plant or equipment such as Z blade or high shear mixers, the surfactant or surfactants being added at a convenient time and in the required proportions, to become homogeneously dispersed in the paste or slurry. It is contemplated that two or more surfactants may be employed together, suitable surfactant mixtures thus being used when desired.
• drying of the paste or slurry, rendering of the solid product into particulate form, and classifying the solid particulate product may be carried out in more-or-less conventional manner.
• drying of the paste or slurry in an oven, and hand granulation eg forcing the material through a screen
• spray drying of the slurry whereby the slurry is pumped through an orifice in a two fluid nozzle while simultaneously passing compressed air through the nozzle, to atomize the slurry into droplets, with the resultant droplets being dried by means of hot air, thereby to obtain more-or-less spherical product particles, may be employed.
• burning rates of delay elements made from delay compositions are controlled or modified by altering the particle size and/or the oxidizer:fuel mass ratio in the mixture.
• the oxidizer:fuel ratio has upper and lower limits, beyond which the compositions can no longer reliably sustain combustion. It is thus a feature of the present invention that its technique for controlling burning rates avoids or reduces these problems.
• the invention extends also to a pyrotechnic delay composition when produced in accordance with the first aspect of the invention.
• a pyrotechnic delay composition which is in solid, particulate form, with the particles comprising an oxidizer, a fuel and a surfactant.
• the oxidizer, fuel and surfactant may be as hereinbefore described.
• the delay composition may comprise, on a mass basis,
• Pyrotechnic delay compositions in accordance with the invention, were formulated having the following compositions (proportions expressed as % by mass):
• the pyrotechnic delay compositions were produced as follows: The oxidizers, fuel and surfactant were mixed by hand or by using a high shear mixer, together with sufficient water, to obtain a slurry; the slurry was then oven dried to a consistency that allowed hand granulation by pushing the dried product through a 1 mm screen; thereafter, the resultant granules were further oven dried to reduce the water content to less than 1%, by mass.
• Solsperse 20000 is manufactured by Avecia, and distributed in South Africa by Lubrisol.
• composition comprising 1% Solsperse 20000 and 54% red lead had a burning rate of 19 milliseconds/mm in 3.6 mm inner diameter aluminum tubes, whereas, for the composition comprising 2% Solsperse 20000 and 53% red lead the burning rate decreased to a value of 80 milliseconds/mm.
• Pyrotechnic delay compositions in accordance with the invention, were formulated having the following compositions (proportions expressed as % by mass):
• the pyrotechnic delay compositions were produced in the same manner as in Example 1.
• the Acrinol 296D was obtained from BASF SA (Pty) Limited of 852 1 6th Road, Midrand, Gauteng, South Africa.
• composition comprising 1 % Acrinol 296D and 54% red lead had a burning rate of 22 milliseconds/mm in 3.6 mm inner diameter aluminum tubes, whereas, for the composition comprising 4% Acrinol 296D and 51% red lead the burning rate decreased to a value of 55 milliseconds/mm.
• a pyrotechnic time delay composition was prepared (as hereinafter described) having the following composition in terms of solids on a dry basis (proportions expressed as % by mass):
• All four the dry particulate constituents were homogeneously mixed with water to form a slurry in which the water formed 50% by mass, with the solids thus forming 50%.
• the BENTONE®EW was obtained from Carst & Walker (Pty) Limited of Zenith House, 12 Sherborne Road, Parktown, Africa.
• the slurry was pumped, at a low pressure of 10-100kPa, along a feed line and through a 1.5mm or 2 mm diameter orifice of a centrally positioned (in a spray-drying chamber) upwardly directed two fluid spray nozzle (together with compressed air), thereby being atomized and thus formed into droplets, while low pressure air at a temperature of 210° C.
• the dried product was found to comprise acceptably low proportions of both oversize and undersize particles which could be used, without additional classifying, as a pyrotechnic time delay composition in the manufacture of pyrotechnic time delay elements.
• a pyrotechnic time delay composition was prepared (as hereinafter described) having the following composition in terms of solids on a dry basis (proportions expressed as % by mass):
• the pyrotechnic time delay composition was produced in the same manner as that of Example 3.
• the dried product was found to comprise acceptably low proportions of both oversize and undersize particles which could be used, without additional classifying, as a pyrotechnic delay composition in the manufacture of pyrotechnic time delay elements.
• an oxidizer such as red lead is used to import sensitivity into the composition, particularly for compositions having a slow burning rate, e.g. about 210 ms/mm. It has thus unexpectedly been found that, by employing a surfactant in accordance with the invention in the production of a pyrotechnic time delay composition, it is possible to eliminate the use of red lead, which is desirable due to the hazardous nature of red lead, while still obtaining acceptable burning rates.
• the surfactant used is such that little or no gas is generated by the surfactant when the composition burns. Gas generated by the burning surfactant could lead to malfunctioning of a delay element incorporating the composition.

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• Chemical & Material Sciences (AREA)
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• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
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Citations (5)

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• 2007
  • 2007-09-14 CL CL200702676A patent/CL2007002676A1/es unknown
  • 2007-09-19 AU AU2007298523A patent/AU2007298523A1/en not_active Abandoned
  • 2007-09-19 BR BRPI0715148-9A patent/BRPI0715148A2/pt not_active IP Right Cessation
  • 2007-09-19 WO PCT/IB2007/053781 patent/WO2008035289A2/en not_active Ceased
  • 2007-09-19 CA CA002663955A patent/CA2663955A1/en not_active Abandoned
  • 2007-09-19 US US12/442,108 patent/US20090314397A1/en not_active Abandoned
  • 2007-09-19 AP AP2009004805A patent/AP2009004805A0/xx unknown
  • 2007-09-19 EP EP07826439A patent/EP2064165A2/en not_active Withdrawn
  • 2007-09-19 PE PE2007001261A patent/PE20080530A1/es not_active Application Discontinuation
  • 2007-09-19 MX MX2009003008A patent/MX2009003008A/es unknown
  • 2007-09-20 AR ARP070104165A patent/AR062924A1/es unknown
  • 2007-09-20 ZA ZA200708113A patent/ZA200708113B/en unknown
• 2009
  • 2009-04-16 MA MA31792A patent/MA30796B1/fr unknown

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