WO2002081411A2

WO2002081411A2 - Modifier of emulsion explosive

Info

Publication number: WO2002081411A2
Application number: PCT/SK2002/000003
Authority: WO
Inventors: Eduard Jakubcek; Jozef BOHÁCIK; Stefan Gazda; Mária MAKOVINSKÁ; Svatopluk Zeman; Karel Bezkocka; Petr KOHLÍCEK
Original assignee: Istrochem, A.S.
Priority date: 2001-04-05
Filing date: 2002-04-05
Publication date: 2002-10-17
Also published as: SK285615B6; PL367936A1; BG108313A; RU2286326C2; CZ20033010A3; RU2003132427A; SK4622001A3; WO2002081411A3

Abstract

A modifier of brisance (i.e. shattering effect) for water-in-oil emulsion explosives, composed of a macromolecular component consisting of a prepolymer or polymer with the construction units-[CH2-C(X)=CH-CH2]-in its macromolecule where X is -H or -CH3, and which is terminated by hydroxi- or isocyanate groups or polyisobutylene groupings. Its use in an emulsion explosive reduces its brisance while preserving its working ability and raising the physical consistency of this explosive.

Description

A modifying agent for emulsion explosives

Field of the Invention

The invention concerns a modifying agent for the brisance of "water in oil"-type emulsion explosives, consisting of a macromolecular component based on butadiene (liquid rubber) or isobutylene.

Description of the related art

If we look at "water in oil"-type (code name W O) emulsion explosives as a mixture of chemical components, they constitute an oxidising-reductive system as in the majority of mixture explosives. The mixture of fuel and oxidizer is completed with a suitable non- explosive sensitizer, which is able to participate in the generation of hot cores for initiating and expanding the chemical reaction in detonation.

In the majority of mixture explosive systems the basic oxidizer is ammonium nitrate, often in combination with other nitrates (e.g. sodium, potassium, calcium, lithium and other similar nitrates) or perchlorates (sodium or ammonium). An almost indescribably broad range of fuels is used, mainly carbonaceous compounds of mineral and/or synthetic origin (see e.g. W. Xuguang: Emulsion Explosives. Metallurgical Ind. Press, Beijing, 1994). The most commonly used fuels are paraffin oils and waxes, mineral and vegetable oils, petroleum, microcrystalline waxes, and other petroleum fractions. The choice of fuel or fuel mixture is determined by the demands on the rheology of the resulting explosive as well as its physical and storage stability. In certain circumstances, another component of the fuel phase may be metal powders (especially aluminium) and individual explosives (demilitarised trinitrotoluene and/or hexogen and demilitarised propulsion explosives).

In classic water-in-oil emulsion explosives it is a rule that the oxidising and fuel components are present in a liquid state: a discontinuous phase of the oxidizer, in the form of a supersaturated solution of the oxidizer in the form of microspheres and other water-soluble additives, is dispersed in the continuous (oil) fuel phase (the continuous phase creates a film on the microspheres of the oxidizer phase). The creation of a continuous and stable boundary between the continuous and discontinuous phase is achieved by adding lipophilic-hydrophilic components (i.e. emul sifters) to the oil phase The emulsifiers most widely used in technical practice are sorbitan monooleates and/or sequioleates.

The film on the continuous phase can be reinforced and the physical stability of the resulting emulsion (emulsion matrix) can be increased by the addition of oligomers, polymers and/or copolymers (see e.g. W. Xuguang: Emulsion Explosives. Metallurgical Ind. Press, Beijing, 1994). The art also includes the description and use of oligomers, polymers and bitumens based on isobutylene and butadiene (see e.g. Can. Pat. Appl. CA 2, 107,966, 1994, or Jpn. Kokai Tokkyo Koho JP 59, 156,991, 1984): here especially hydroxide terminated liquid polybutadiene has a positive effect, increasing the stability of the emulsion Hydrophilic terminated polyisobutylenes sometimes figures in the production of this sort of explosive as polymeric emulsifiers whose use can significantly extend the working life of the product. Extraordinarily large interface surfaces in the matrix of emulsion explosives pi ovide perfect contact between the two phases, the most perfect of all industrial mixture explosives This fact also means that there is a short reaction zone in the detonation wave with suitable sensitization and initiation the described type of explosive can be considered equal to dynamites, because of the system's significant reactivity and high usable energy yield, as well as its effect in rock blasting

Compared to dynamites (i e explosives containing niti oeslei s), emulsion explosives have a range of significant advantages, such as its non-sensitivity to mechanical stimuli, flames and sparks, its high water resistance, and its minimal physiological activity, not only in its own emulsion composition but also in the by-products of the explosion On the other hand, emulsion explosives can be phlegmatized, even totally desensitized, by dynamic shock, especially a strong compression stress wave caused by the detonation of a neaiby charge in rock Another disadvantage is that only Category One mine safe explosives can be produced from emulsion explosives Both these disadvantages result from the relatively high brisance (/ e shattering effect) of this type of explosive

The most widespread principle in the construction of mine safe explosives containing nitroesters is to include cooling additives (most often sodium chloride) or cooling ion exchange systems (e g mixtuies of ammonium chloride and sodium nitrate) in the explosive mixtures This results in a reduction in the working ability and brisance of the resulting explosive compared to nitroester explosives without cooling additives Howevei, as is shown by the example sections of this invention, analogical inclusion of sodium chloride up to 10% of the mass of emulsion explosive reduces its working ability but increases its brisance In this way, the cooling effect of the admixtures mentioned above can be eliminated to certain extent The problem of the brisance of emulsion explosives is consequently the decisive factor in the construction of mine safe explosives on this basis The previous hteiatui e has paid little attention to the systematic study of the effect on emulsion explosives' brisance aπsing from the chemical composition of the components of the reductive-oxidizing system of these explosives

Summary of the invention

According to the procedure described in this invention, the brisance of a watei-m-oil emulsion explosive is modified by adding macromolecular components based on butadiene and isobutylene to the oil phase An advantage of this procedure is that a relatively small addition of these macromolecular components (0 5 to 1 8% of the mass of the lesultmg explosive) significantly reduces brisance while maintaining the working ability of the emulsion explosive, while at the same time increasing the stability and modifying the consistency the resulting explosive so that when cooling additives are included in its composition it becomes an explosive in the first category of mining safety Anothei advantage of the procedure described in this invention is the availability of these maci omolecular components, which are produced industrially for the needs of the plastics and aibber industry as well as for the needs of producing special kinds of explosives

The use of macromolecular components based on butadiene and isobutylene as descπbed in this invention has not previously been described in the liteiature It is documented by the following examples, which in no way exclude possible variations in the manner of use Examples of the implementation of the invention

Example 1

A solution of ammonium nitrate (AN) or sodium nitrate (SN) and/or Calcium Nitrate (CN) and/or sodium perchlorate (SP), having a temperature of 85- 100°C, and possibly containing other water soluble components such as sodium chloride (NaCl), glycol or similar, is fed into an emulsification apparatus containing a warm oil phase (80-85°C) that has been mixed intensively (a mixer with 1000 to 1500 rpm). This oil phase consists of mineral oil (with an average mass of 910 kg.m with a max. setting point -5°C and a mm. flash point 66°C) and/or slack wax (setting point 39°C and flash point 220-260°C, and oil content about 1.5% of mass), plus sorbitan monooleate (M) and/or sorbitan sesquioleate (S), possibly also macromolecular components. When the feed of aqueous salt solution is completed, the mixture must be mixed for 5 more minutes. The emulsion matrix obtained in this way is sensitized in a homogenizer by the addition of silicate microballoons (MB) with an average size of 70 μm, and possibly modified by the addition of solid sodium chloride (NaCl) with an average grain size of 80 μm. The resulting explosive mixture is loaded into plastic tubes to make cartridges weighing 400g with a diameter of 32mm. Charge mass velocity of detonation (D, using a no. 8 detonator) and relative working ability ( VVA) were determined for each cartridge. A summary of the composition of individual mixtures prepared in accordance with this procedure, is given in the table, together with the relevant values for p, D and RWA.

The following macromolecular components were added to the oil phase

■ Liquid polybutadiene rubber (LBH) terminated with hydroxyl groups with an average molar weight 2400 - 3100, a polydispersity index of cca 1. 1 and hydroxyl content cca 0,7 mmol.g^"1, in which the number of structural construction units of its macromolecule -[CH₂-CH=CH-CH₂]- is cca 44 to 57.

■ Liquid isocyanate prepolymer (LBD - terminated with isocyanate tolylene groups) with a polybutadiene backbone chain, with an average molar weight 3200 - 3800, a polydispersity index of cca 1.3 and functionality cca 2.2, in which the number of structural construction units of its macromolecule -[CH -CH=CH-CH₂]- is also cca 44 to 57.

■ A solid copolymer polyisobutadiene (PIB) with 2 % mol. of isoprene with an average molar weight 200 000 of general structural pattern:

— [— (C(CH₃)₂-CH₂— )_m— <— CH₂-C(CH₃)=CH-CH₂— )„— ] — where m » n.

In some emulsion mixtures containing LBD, in particular mixtures 1.1 , 1.3 and 1.4 in the table, a cross-linking catalyst was used. This produced plastic, well-shapeable matrices that could be filled with crystalline additives up to 50% of their mass without losing the cohesion of the final mixture. The macromolecular additives in question also extended the durability of emulsion explosives containing them (min. 6 months) compared to emulsion explosives without them (durability 3-6 months). Example 2

This was carried out following Czechoslovak patent no 229 745 (1982)' a solution of ammonium nitrate (AN) and sodium nitrate (SN) 80-90°C warm is placed in an emulsification apparatus A solution of oleic acid in mineral oil is fed into it, followed by an aqueous solution of sodium hydroxide The mixture is mixed until an emulsion forms This emulsion is sensitized in a homogenizer by adding expanded perlite This produces an emulsion explosive containing 62.9 % by mass AN, 13% SN, 12% water and 2 5% Sodium hydroxide, 2 8%o oil, 2 8% oleic acid and 4% expanded perlite, which is registered under the name Emsit Its average charge mass is 1 06 g.cm^" , velocity of detonation D = 4817 m s^" and relative working ability RPS = 69 5 %

Example 3

This example formulates the graphic dependency of the relative working ability of the emulsion explosives in examples 1 and 2 on their brisance, represented by the product of average charge weight and the square of velocity of detonation expressed as p*D It follows from this dependency that macromolecular components of the oil phase in example 1 significantly reduce the brisance of the relevant emulsion explosives compared to explosives that do not use these components (including the E sit in example 2) This effect has significance for mine-safe explosives The graphic dependency means that, in both groups of emulsion explosives, an increase in the amount of solid particles with higher molar weight they contain results in a decrease the value of RWA and an increase in brisance (this is valid also for mineral sensitizer content)

Example 4

When 1050g of explosive mixture 1 7 from the table in example 1 is detonated in the form of 32mm diameter cartridges, it does not ignite a methane-air mixture with a 9% by volume methane content or 1200g of coal dust mixed with air, where the dust had a concentration of 300 g m^"3 The boundary charge for this explosive (diameter 32mm) has been established at 1241 ±72 g The gas products of its detonation do not include nitrous oxides

Industrial application

The production of a water-in-oil emulsion suitable for finishing as an emulsion explosive with reduced shattering and preserved displacement effects, for example an explosive with increased safety for mining

Claims

P A T E N T C L A I M S

A modifying agent of water-in-oil emulsion explosives in which the discontinuous phase consists of an aqueous solution of anorganic nitrates and/or perchlorates, possibly also other components of an anorganic or organic character, and possibly also containing a cooling component of the anorganic chloride group, characteriszed in that it consists of a prepolymer or polymer with the construction units — [CH -C(X)=CH-CH ] — in its macromolecule, where X is -H or -CH₃, and which is terminated by hydroxi- or isocyanate groups or polyisobutylene groupings.

A modifying agent of emulsion explosives under point 1 characterized in that it constitutes 0.5 to 1.8%, ideally 0.6 to 1.57%, of the mass of the explosives, calculated from the mass of the finished emulsion explosives.