Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
  • C06C7/00—Non-electric detonators; Blasting caps; Primers
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B35/00—Compositions containing a metal azide
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B43/00—Compositions characterised by explosive or thermic constituents not provided for in groups C06B25/00 - C06B41/00
• • 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

Definitions

• the molybdenum disulphide may be incorporated by first dispersing it in a colloid solution and subsequently precipitating lead azide from the solution by the conventional technique of adding a water-soluble azide and a water-soluble lead salt.
• dry molybdenum disulphide may be mixed with dry lead azide.
• This invention relates to lead azide compositions suitable for use as primary initiating explosive compositions (hereinafter referred to as the primary charge) in detonators and to processes for the preparation thereof.
• the lead azide In the manufacture of detonators containing lead azide in the primary charge the lead azide is pressed, by a punch, at a high pressure into a tubular casing on top of a base charge of secondary explosive.
• the lead azide used hitherto has tended to adhere to the pressing punches giving rise to risk of accidental explosion on Withdrawing the punch, due to the sensitivity of the lead azide to friction.
• This risk is increased if the lead azide primary composition contains, as it often does, lead styphnate (lead trinitroresorcinate) to increase the cohesion and the sensitivity to initiation by burning safety fuse, since the lead styphnate has an even stronger tendency to adhere to press punches.
• Hitherto lead azide compositions have usually contained a small proportion of fine aluminum to act as a lubricant to prevent adhesion to the punches but the aluminum increases the sensitivity of compositions containing lead styphnate to ignition by electrostatic discharge and is generally inconvenient in detonator manufacture because the dry mixing process by which it is incorporated is conducive to the accumulation of electrostatic charge and to the spread of the dry aluminum as airborne dust.
• molybdenum disulphide is effective in treating lead azide to reduce its adhesion to press punches and that this treatment is also effective for lead azide primary charges containing lead styphnate.
• a lead azide composition suitable for use in a detonator primary composition comprises lead azide and molybdenum disulphide.
• the composition may also comprise lead styphnate.
• the molybdenum disulphide is preferably in the form of a fine powder having an average particle diameter size of less than 20 microns.
• a marked reduction in the tendency of the lead azide composition to adhere to the press punches can be accomplished by the use of small proportions of molybdenum disulphide.
• molybdenum disulphide For practical purposes it is not usually necessary to use more than 4% by weight of the composition and a high degree of freedom from adhesion can be achieved by using 0.1% by Weight.
• the lead azide composition of the invention may be prepared by mixing the molybdenum disulphide with the lead azide in the dry state but in a preferred method it is dispersed in a liquid medium, conveniently water, before mixing with the lead azide. Since the lead azide is invariably formed by effecting the formation of a solid precipitate in an aqueous solution of a colloid, such as, for example, gelatine or dextrin, by reacting a waters'oluble azide and a water-soluble lead salt, it is advantageous to disperse the molybdenum disulphide in the said colloid solution.
• a colloid such as, for example, gelatine or dextrin
• the colloid solution usually contains in solution caustic soda, Rochelle salt and a colloidal material such as, for example, gelatine or dextrin, or a mixture thereof, and a dispersion of molybdenum disulphide can be readily prepared in such solution. It is preferred, however, to avoid using dextrin as the colloid since the azide crystals formed in presence of dextrin and molybdenum disulphide are rather sensitive to grit and electrostatic discharge. An azide having slightly better cohesion is obtained if the caustic soda is omitted. A Wetting agent dissolved in the colloid solution accelerates the dispersion of the molybdenum disulphide.
• compositions containing lead styphnate may be prepared by adding the molybdenum disulphide to a preformed mixture of lead azide and lead styphnate but it is more convenient to treat the lead azide separately with molybdenum disulphide and subsequently to incorporate the lead styphnate which may, if desired, also be treated with molybdenum disulphide prior to its incorporation.
• the treatment may advantageously be elfected by forming a lead styphnate precipitate by reaction of a water-soluble lead salt and a water-soluble styphnate in an aqueous solution of a colloid in presence of a dispersion of molybdenum disulphide.
• the lead azide compositions of the invention are satisfactory in all other important respects.
• the sensitivity to ignition by electrostatic discharge and by burning safety fuse is not materially affected and its ability to initiate secondary explosive is somewhat enhanced.
• Example 1-15 the colloid was nonfoaming gelatine containing 0.2% of n-octyl alcohol as antifoaming agent, and in Example 16 it was dextrin.
• the solution containing the sodium azide also contained 0.12% of caustic soda.
• the base solution contained one drop of a wetting agent available commercially as Lissapol NX (Registered Trademark) to facilitate dispersion of the molybdenum disulphide.
• the lead azide of Example 16 wherein dextrin was used as the colloid was in the form of irregular sharp-pointed crystals which had for their tendency to adhere to press punches.
• the results show that the mixtures were as suitable for use in detonator initiating explosive charges as pure lead azide except that with the higher molybdenum disulphide concentrations the amount required to initiate PETN was higher.
• composition suitable for use in a detonator primary charge comprising lead azide and molybdenum disulphide.
• composition as claimed in claim 1 comprising additionally lead styphnate.
• a composition as claimed in claim 1 wherein the molybdenum disulphide is in the form of a fine powder 5 having an average particle diameter size of less than 20 microns.
• composition as claimed in claim 1 containing 0.1 to 4% by weight of molybdenum disulphide.
• a lead styphnate composition suitable for use in detonator primary compositions comprising lead styphnate and molybdenum disulphide.
• gelatine 10 is a non-foaming gelatine.
• gelatine solution comprises n-octyl alcohol as an anti-foaming agent.
• a lead styphnate composition for use in a detonator primary charge by precipitating lead styphnate from an aqueous colloid solu- 6 tion by adding thereto a water-soluble styphnate and a water-soluble lead salt the improvement which comprises dispersing molybdenum disulphide in said solution before precipitating lead styphnate.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Air Bags (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)

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Publications (1)

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Country Status (7)

Cited By (5)

Citations (2)

• 1965
  • 1965-08-09 GB GB34008/65A patent/GB1098606A/en not_active Expired
• 1966
  • 1966-07-28 US US568399A patent/US3361602A/en not_active Expired - Lifetime
  • 1966-08-04 FI FI662046A patent/FI44999C/fi active
  • 1966-08-05 AT AT751466A patent/AT265085B/de active
  • 1966-08-09 BE BE685279D patent/BE685279A/xx unknown
  • 1966-08-09 DE DE1966J0031506 patent/DE1571266B1/de active Pending
  • 1966-08-09 ES ES0330078A patent/ES330078A1/es not_active Expired

Patent Citations (2)

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