Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
• • 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
  • C06B23/04—Compositions characterised by non-explosive or non-thermic constituents for cooling the explosion gases including antifouling and flash suppressing agents
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
  • C06B47/14—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase comprising a solid component and an aqueous phase
  • C06B47/145—Water in oil emulsion type explosives in which a carbonaceous fuel forms the continuous phase

Definitions

• This invention relates to a water/melt-in-oil emulsion explosive composition suitable for use in a flammable environment, particularly underground,and especially in a coal mine.
• the invention particularly also relates to an emulsion which would qualify as P1 or P5 permitted explosives as set out by the UK regulatory authority.
• emulsion explosive compositions generally comprise an external or continuous organic fuel phase in which discrete droplets of an aqueous solution of an oxygen-supplying salt are dispersed as an internal or discontinuous phase and are stabilised by an emulsifier, which is believed to exist as a molecular coating layer on the surface of the droplets to reduce incipient agglomeration thereof.
• Such compositions are conventionally described as water-in-oil (w/o) emulsion explosive compositions; and examples thereof have been described, inter alia, in US patents 3 447 978, 3 674 578, 3 770 522, 4 104 092, 4 111 727, 4 149 916, 4 149 717, 4 490 194.
• the water content of the oxidiser phase of the emulsion explosive may be completely eliminated or at least reduced to a low level - for example, to less than 5% by weight of the total emulsion composition.
• Such compositions are conventionally referred to as melt-in-­oil (m/o) or melt-in-fuel emulsion explosive and have been described, inter alia, in US patent 4 248 644.
• density reducing agents such as entrained gas, either introduced mechanically or formed in situ by chemical reagents, or microballoons, perlites, polyurethene, or expanded polystyrene are added to control the density of the emulsion and ensure adequate detonator sensitivity.
• Emulsion explosives however, have a high weight strength (explosive power expressed as a percentage of that of blasting gelatine % BG) and a high velocity of detonation (VOD), which although ideal for most blasting applications, presents a problem with underground work such as in coal mines where there is a flammable atmosphere.
• Emulsions of the invention are regarded as stable if they have a shelf life of at least 3 months, preferably 6 months; and detonator sensitivity is a well known term in the art.
• a detonator sensitive, stable, water-in-oil or melt-­in-oil emulsion explosive comprising an oxidiser containing discontinuous phase, a fuel containing continuous phase, and an emulsifier, characterised in that there is from 7% to 15% w/w of a cooling agent dissolved in the oxidiser containing discontinuous phase and selected from a soluble phosphate salt, sulphonate, sulphate, phosphonate, ammonium halide, alkali metal halide, and an alkaline earth metal halide.
• the invention has the advantage of emulsion explosives, but differs from standard emulsions in that it can be detonated more safely in a flammable atmosphere.
• a major advantage of the invention is that emulsion explosives can now be formulated in a more cost effective and controllable manner and which will pass at least United Kingdom permitted tests.
• a P1 (approved explosive of the UK regulatory authorities) emulsion explosive can be obtained having a VOD of about 4200 m/s to 4500 m/s and a weight strength of about 55 to 60% BG, for about 7% w/w of dissolved cooling agents.
• the resulting emulsion explosive would have a VOD of about 4000 m/s and a weight strength of about 50 to 55% BG.
• As much as about 15% w/w of a sufficiently soluble cooling agent could be dissolved with an advantageous further reduction in the resulting VOD and weight strength.
• a P1 explosive can be achieved by only dissolving the cooling agents in the discontinuous phase of the emulsion explosive, for stricter tests such as the P5 (explosive approved by the UK regulatory authorities) emulsion explosive some cooling agent must also be added to the continuous phase to a value allowing for at least 20% w/w of cooling salts to be distributed throughout the emulsion. Therefore in accordance with the invention, an amount of from 7% to 15% W/W, preferably 10% to 15% w/w. and particularly about 12% to 13% w/w, of cooling agent is dissolved in the discontinuous phase, and the desired extra quantity added as solids to the continuous phase.
• the invention is very flexible in that it is possible to modify the explosive properties, such as the weight strength and VOD to suit the particular blasting environment. For example in underground rock blasting it may be preferred to have P1 explosive with a higher VOD, whereas in coal mines where a P5 explosive is required, a lower VOD may be desired.
• a further advantage of the invention is that only a reasonably low level of emulsifier at most about 3% w/w and preferably 1.0 to 1.5% w/w of the emulsion explosive, is required.
• the explosive can therefore be substantially oxygen balanced and will not produce what would be regarded as an unsafe amount of uncombusted toxic gas in the after detonated fumes, which is important for underground or similarly poorly ventilated work. For open cast blasting this consideration is less significant.
• the resultant emulsion explosives have a shelf life of at least 3 months and preferably at least 6 months, and can still retain detonator sensitivity without recourse to adding self-explosive materials such as methylamine mononitrate, ethylene diamine dinitrate, nitroglycerine, or sodium perchlorate.
• sensitisers and in fact high levels of emulsifier could be added if desired, but they are not necessary to achieve the stable, detonator sensitive emulsion explosive of the invention.
• an excess of emulsifier could substitute for some or all of the conventionally used fuel, but this may not be desirable.
• the invention can be pumped, loaded or poured to be used, for example, in blasting operations in oil shale or underground mining where regulations permit, or preferably can be packaged into standard cartridges.
• a method of preparing a borehole for blasting in a flammable environment comprising pumping, pouring, loading an emulsion explosive into the borehole, or inserting a cartridge of emulsion explosive into the borehole, wherein the emulsion explosive is as defined in the first aspect of the invention.
• the density of the invention emulsions can be controlled by known methods such as by the use of density reducing agents discussed heretofore, the density preferably varying between 0.8 to 1.2 g/cm3.
• a w/o emulsion and m/o emulsion having a water content of less than 5% w/w
• a w/o emulsion is preferred having a water content of from 5% to 20% w/w, and more preferably from 10% to 15% w/w.
• chlorides are preferred, as are also the alkali or alkaline earth metal cooling agents especially the chlorides thereof.
• a very high amount of KC1 and CaCl2 can be loaded into the discontinuous phase to achieve very desirable VOD values suitable for permitted explosives.
• These (KC1 and CaCl2) especially preferred cooling agents can of course be distributed along throughout the continuous or noncontinuous phase alone or in combination with any other known cooling salt, for example NaCl or MgCl2.
• the fuel used which is preferably present at up to 10% w/w of the emulsion explosive, is typical for an emulsion explosive and would comprise, for example of the following: mineral oils, fuel oils, lubricating oils, liquid paraffin, micro crystalline waxes, paraffin waxes, petroleum, and slack wax.
• typical oxidisers for the discontinuous phase preferably at around 30% w/w of the emulsion explosive would be NH4NO3, NaHO3, Ca(NO3)2, and KNO3, either in the melt or in an aqueous medium.
• Such salts could also be added as particulate solid to the formed emulsion.
• emulsifiers for given emulsion systems are known in the art, but preferred emulsifiers for emulsion explosive compositions are sorbitan esters (mono- and sesquioleates; SMO and SSO resp.) and the reaction product of coupling a polyisobutenyl chain (functionalised with, for example succinic anhydride) with a hydrophilic head group such as an ethanolamine or substituted ethanolamine e.g. mono- and diethanolamines such as those disclosed in EP-A-0 155 800.
• sorbitan esters mono- and sesquioleates; SMO and SSO resp.
• a hydrophilic head group such as an ethanolamine or substituted ethanolamine e.g. mono- and diethanolamines such as those disclosed in EP-A-0 155 800.
• Mixtures of a PIBSA-type emulsifier (which provides for long term storage stability), and a more conventional emulsifier such as a sorbitan ester (which provides rapid droplet stabilisation and so resists any tendency for droplet coalescence) are especially preferred in this invention.
• the normal way of assessing the safety of an explosive intended for use in a coal mine in the U.K. is by a series of gallery tests, details of which are contained in Testing Memorandum No. 2(TM 2) published by the U.K. Health and Safety Executive, Buxton.
• the testing gallery consists of a steel cylinder. The first part is sealed with a polythene diaphragm to contain the flammable atmosphere and the remaining part is left open. At the end opposite of the diaphragm there is a hole against which a heaby steel cannon containing the explosive is placed. The joint is sealed by a rubber ring.
• a water-in-oil emulsion explosive with the following composition was prepared:- Component Percentage by weight Ammonium Nitrate 65.97 Potassium Chloride 12.57 Water 13.41 Emulsifier 1.26 Oil/Wax blend 3.18 Glass microspheres 3.60
• the potassium chloride was dissolved completely at about 90-95°C in a hot solution of the nitrate salts.
• the resulting solution was then combined with the emulsifier and oil/wax blend to form a w/o emulsion with an average droplet size of less than 5 microns, typically about 1 to 3 microns, in the conventional manner.
• the microspheres were then dispersed into the material to give a resulting explosive composition with a density of 1.05 g/cm3.
• the unconfined velocity of detonation was 4,000 cm/s at a diameter of 35mm packaged in a plastic film. All other experiments were carried out in a similar 35mm tube. The weight strength was found to be 50%BG.
• a water-in-oil emulsion explosive with the following composition was prepared.
• Component Percentage by weight Ammonium Nitrate 58.01
• Potassium Chloride 9.48
• Water 11.60 Emulsifier 1.46 Oil/Wax Blend 4.59 Glass Microsphere 5.00
• the potassium chloride was dissolved completely in the hot solution in oxidiser salts and then formed into an emulsion explosive in the conventional manner.
• the resulting explosive had a density of 0.99 g/cm3.
• the incendivity of this composition was tested in the P1 condition according to TM 2.
• seven shots were fired at a test weight of 200g. No ignition was observed.
• five shots were fired at a test weight of 800g.
• the unconfined VOD was 4200 m/s. Since no ignitions again were observed, this indicated a P1 type explosive.
• a water-in-oil emulsion explosive with the following composition was prepared:- Component Percentage by weight Ammonium 46.09 Sodium Nitrate 7.68 Water 12.10 Sodium Chloride 12.69 Potassium Chloride 12.40 Emulsifier 1.04 Oil/Wax blend 2.63 Glass microsphere 5.37
• the potassium chloride was dissolved completely in the hot solution of nitrate salts at about 90 to 95°C.
• the resulting solution was then combined with the emulsifier and oil/wax blend to form a w/o emulsion in the conventional manner.
• the solid crystalline sodium chloride was then dispersed into the preformed emulsion in a similar manner to that commonly used for the dispersion of glass microspheres. Finally, the said microspheres were themselves dispered into the material to give a resulting explosive composition with a density of 0.95 g/cm3.
• the unconfined VOD was 3500 m/s, and the weight strength was 38% BG.
• Deflagration test Another type of testing other than Gallery testing which is specified in TM 2 for P5 class explosives (but not for the P1 class) is the so called Deflagration test. The details of this test are described in TM 2. This explosive composition was subjected to the demands of this test and the results are summarised below. Explosive Diameter Aperture No. of Deflagrations 37mm 1/8 inch 0/5 35mm none 0/5 35mm 1/8 inch 0/5 35mm 2/8 0/5 35mm 3/8 0/4
• a water-in-oil emulsion explosive with the following composition was prepared in the same manner as Example 1, but without the dissolved cooling salt:- Component Percentage by Weight Ammonium Nitrate 62.2 Sodium Nitrate 12.4 Water 16.0 Emulsifier 1.35 Paraffin Oil 0.91 Paraffin Wax 1.91 Microcrystalline Wax 1.92 Glass microsphere 3.31
• the density of this composition was 1.11 g/cm3.
• a water-in-oil emulsion explosive with the following composition was prepared:- Component Percentage by Weight Ammonium Nitrate 30.57 Norsk-Hydro Calcium Nitrate 28.63 Methylamine Mononitrate (70% solution) 7.10 Emulsifier 1.25 Oil 3.95 Potassium Sulphate 22.50 Glass microspheres 6.00
• a hot solution of the nitrate salts was prepared and added to the oil/emulsifier at about 90-95°C in the conventional manner to form a w/o emulsion.
• the solid potassium sulphate and the microspheres were added to produce a explosive composition.
• the resulting density of this explosive composition was 0.98 g/cm3.
• the unconfined VOD was 3000 m/s and the weight strength was 40% BG.
• any alkali metal halide, alkaline earth metal halide or ammonium halide will be suitable, as in fact will any phosphonate, sulphonate, sulphate or sufficiently soluble phosphate salt.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Crystallography & Structural Chemistry (AREA)
• Liquid Carbonaceous Fuels (AREA)
• Colloid Chemistry (AREA)

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• 1989
  • 1989-04-10 GB GB898907992A patent/GB8907992D0/en active Pending
• 1990
  • 1990-03-27 GB GB9006784A patent/GB2230257A/en not_active Withdrawn
  • 1990-03-27 EP EP19900303250 patent/EP0393860A3/fr not_active Withdrawn
  • 1990-04-02 NO NO90901497A patent/NO901497L/no unknown
  • 1990-04-02 ZA ZA902522A patent/ZA902522B/xx unknown
  • 1990-04-02 MW MW24/90A patent/MW2490A1/xx unknown
  • 1990-04-11 AU AU53131/90A patent/AU617607B2/en not_active Ceased

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