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GB2132998A - Emulsion explosive composition containing ferrosilicon - Google Patents

Emulsion explosive composition containing ferrosilicon Download PDF

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Publication number
GB2132998A
GB2132998A GB08329300A GB8329300A GB2132998A GB 2132998 A GB2132998 A GB 2132998A GB 08329300 A GB08329300 A GB 08329300A GB 8329300 A GB8329300 A GB 8329300A GB 2132998 A GB2132998 A GB 2132998A
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GB
United Kingdom
Prior art keywords
explosive
fuel
emulsion
ammonium nitrate
sorbitan
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08329300A
Other versions
GB8329300D0 (en
Inventor
Helen Mcnamara
Pieter Stephanus Jaco Halliday
Jeremy Guy Breakwell Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AECI Ltd
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AECI Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AECI Ltd filed Critical AECI Ltd
Publication of GB8329300D0 publication Critical patent/GB8329300D0/en
Publication of GB2132998A publication Critical patent/GB2132998A/en
Withdrawn legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C06EXPLOSIVES; MATCHES
    • C06BEXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B47/00Compositions 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
    • C06B47/14Compositions 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
    • C06B47/145Water in oil emulsion type explosives in which a carbonaceous fuel forms the continuous phase

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Colloid Chemistry (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
  • Liquid Carbonaceous Fuels (AREA)

Abstract

An explosive in the form of an emulsion which includes a discontinuous phase which includes water, and ammonium nitrate, sodium nitrate and calcium nitrate as oxidising salts; a continuous phase which includes a paraffin hydrocarbon fuel and a hydrocarbon wax fuel; and as a solid fuel component dispersed in the continuous phase, finely divided ferrosilicon.

Description

SPECIFICATION An emulsion explosive having a solid fuel component of ferrosilicon THIS INVENTION relates to an explosive. In particular the invention relates to an explosive of the emulsion type in which an oxidizing salt-containing component forms the discontinuous phase in an emulsion wherein the continuous phase comprises a fuel component which is immiscible with the discontinuous phase.
Such explosives, where the oxidizing salt-containing component contains water and is in the form of an aqueous solution are known as 'water-in-fuel' emulsions, and when the oxidizing salt component includes no water they can be regarded as 'melt-in-fuel' emulsions.
According to the invention there is provided an explosive in the form of an emulsion which includes a discontinuous phase which includes an oxidising salt; a continuous phase which includes a fuel which is immiscible with the discontinuous phase; and as a solid fuel component dispersed in the continuous phase, finely divided ferrosilicon (FeSi).
It is comtemplated that the FeSi will typically be of a particle size comparable to or slightly finer than paint fine or flake aluminium. A suitable FeSi is available from G 8 W Base a Industrial Minerals (Proprietary) Limited, Wadeville, Transvaal, as 'Milled Ferrosilicon'. It is a finely ground charcoal grey powder, an alloy of iron and silicon, conforming with the following specification: PROPERTY VALUE Silicon content Not less than 70% m/m as Si Silicon and Iron Content Not less than 90% m/m as Si and Fe Phosphorus content Not more than 0,05% m/m as P Arsenic Content Not more than 0,05% m/m as As Specific Surface Area Not less than 10 000 cm2/cm3 Particle size 10,um (ie 1 X 10-5m)mean particle size.
The FeSi will thus be finer than atomised aluminium (which has a mean particle size in the order of about 50 microns ie 5 x 1 0 - 5m). However, the above specification is merely illustrative and it is believed that any FeSi of comparable or higher (or even lower) purity can be used, provided it has a comparable particle size and routine testing is all that will be necessary to determine the suitability of a particular FeSi powder and the proportion in which it is to be used, to take into account variations in particle size and composition.
The FeSi is intended as an energetic fuel for at least partially replacing the aluminium typically used in emulsion explosives of the type in question. The FeSi may be used together with another solid fuel. For example, for a more energetic fuel, a mixture of FeSi and atomised aluminium in any proportion to one another can be used. The total proportion of the FeSi and other solid fuel together will typically be 2 to 14% m/m, preferably 4-10% mm of the emulsion explosive, ie proportions similar to those typically encountered for atomised aluminium when it is the only solid fuel used.
The emulsion is formed by dispersing the discontinuous phase in the continuous phase when they are both in liquid form, but the expression 'emulsion' is intended to be construed as covering also the emulsions at temperatures below that at which they were formed, so that the discontinuous phase may be a solid. The FeSi is dispersed in the emulsion after the emulsion has been formed, to form a suspension.
The oxidising salt may comprise a member selected from the group consisting of alkali metal nitrates, alkali metal perchlorates, alkaline earth metal nitrates, alkaline earth metal perchlorates, ammonium nitrate ammonium perchlorate, and mixtures of one or more thereof.
The oxidising salt may be present as an aqueous solution.
Instead, the discontinuous phase may comprise ammonium nitrate and a compound which, together with the ammonium nitrate, form a melt which has a melting point which is lower than that of the ammonium nitrate, the compounds being capable of acting as an oxidising salt or fuel.
The liquid fuel may form from about 2 to 25% by mass of the emulsion, preferably being in the region of about 3 to 12% by mass thereof.
The liquid fuel may include an emulsifier, or a mixture of suitable emulsifiers.
The emulsifiers may comprise a member selected from the group consisting of sorbitan sesquioleate, sorbitan monooleate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, the mono- and diglycerides of fat-forming fatty acids, soya bean lecithin, derivatives of lanolin, alkyl benzene suplhonates, oleyl acid phosphate, laurylamine acetate, decaglycerol decaoleate, decaglycerol decastearate, polymeric emulsifiers containing polyethylene glycol back bones with fatty acid side chains, and one or more mixtures thereof.
The liquid fuel will be immiscible with and insoluble in water, and is preferably a non-selfexplosive organic fuel, being for example selected from the group consisting of hydrocarbons, halogenated hydrocarbons and mixtures thereof. Thus the fuel may comprise a member selected from the group consisting of mineral oils, fuel oils, lubricating oils, liquid paraffin, microcrystalline waxes, paraffin waxes, xylene, petrolatum, toluene, dinitrotoluene, and one or more mixtures thereof.
The emulsifiers act as stabilizers to promote the formation of the emulsion and to combat coalescing and/or crystallization of the discontinuous phase.
In general when the discontinuous phase contains water, this water should be kept at a minimum consistent with forming a satisfactory emulsion and consistent with the avoidance of wasted energy arising from steam production upon detonation.
The density of the emulsion will be such as to form a suitable exlosives composition, and preferably may be between 1,30kg/land 1,50 kg/l at 25"C.
The explosive may thus include microballoons or another form of density reducing agent, to provide the emulsion with a desired density, eg 1,15-1,2 kg/l at 25"C. The emulsion may comprise up to 5% by mass of the microballoons, which may be of glass or a polymeric material, and preferably 1,5 to 2,5%, and they can also act to sensitize the explosive.
The following emulsions were prepared and used as control emulsions: CONTROL EMULSION NO. 1 The formulation of this emulsion was as follows: % BY MASS Ammonium Nitrate 59,70 Sodium Nitrate 14,40 Calcium Nitrate 3,60 Water 12,35 P95 Oil 1,90 Sasolwaks M 1,30 Arlacel 83 0,72 Soya Lecithin 0,72 Surfactant 0,31 Atomized aluminium (50 micron 5,00 (ie 5 X 10~5m) (Supramex 2100) The emulsion was prepared in a Hobart mixer having a steamjacketed bowl, with a wire whip according to the following standard method: The oil phase comprising the oil, surfactants, and wax was heated to 85"C in the steamjacketed bowl. With the wire whip rotating at a speed of 285 rpm the aqueous phase comprising the water and oxidising salts was added to the oil phase at a temperature of 85"C.
The resultant emulsion was stirred for another two minutes at the same speed, which was then increased to 591 rpm for a period of ten minutes. After this the product had a petroleum-jelly like consistency. The aluminium was then added, followed by sufficient C15/250 glass microballoons (2,5-3,0 kg/100kg) at 65'Cto bring the density down to 1,15-1,2 kg/l. This product was sensitive to detonation by 0,36g (ie 3,6 X 10-4kg) of pentaerythritol tetranitrate (PETN) in 25mm (ie 2,5 X 10-2m) at 25"C after three months storage at ambient temperature.
The velocity of detonation was 4,1 x 1 O3m/s.
CONTROL EMULSION NO. 2 The formulation of this emulsion differed from that of the control emulsion No. 1 in that the oil and wax components thereof were replaced with an equivalent amount of unprocessed petrolatum, and this emulsion was prepared via the same method as described above for the control emulsion No. 1.
The emulsion detonated with 0,36g (ie 3,6 X 10-4kg) of PETN in 25mm (ie 2,5 x 10-2m at 25"C after four months storage at ambient temperature and after four months storage at 40"C.
The velocity of detonation was 4,1 X 1 03m/s These tests are still in progress so that the maximum storage periods have not yet been established.
EXAMPLE 1 The following emulsion in accordance with the invention was prepared: % BY MASS Ammonium nitrate 59,00 Sodium Nitrate 14,20 Calcium nitrate 3,50 Water 12,15 P95 oil 1,80 Sasolwaks M 1,20 Arlacel 83 0,72 Soya Lecithin 0,72 Surfactant 0,31 FeSi 6,40 P95 is a paraffinic hydrocarbon fuel available from B P Southern Africa (Proprietary) Limited; Sasolwaks M is a hydrocarbon wax fuel available from Sasol Marketing Company Limited; Arlacel 83 is a sorbitan sesquioleate emulsifier available from Atlas Chemical Company; The surfactant is a polymeric emulsifier; and Cm 5/250 microballoons are available from 3M (South Africa) (Proprietary) Limited.
The emulsion was prepared in the same fashion as the control, ecept that FeSi having a particle size of 10m (ie 1 x 10-5m) replaced the atomized aluminium. The emulsion was sensitive to detonation by 0,36g (ie 3,6 x 10-4kg) of PETN in 25 mm (ie 2,5 x 10-2m) at 25"C after three months storage at ambient temperature. The velocity of detonation was 4,1 x 103m/s.
EXAMPLE 2 Example 1 was repeated with 6,4% by mass of a relatively coarse grade FeSi having a particle size of 25,um (ie 2,5 x 10-5m). The emulsion was sensitive to detonation by 0,36g (ie 3,6 X 10-4kg) of PETN in 25mm (2,55 X 10-2m) at 25"C after three months storage at ambient temperature. The velocity of detonation was 4,1 x 1 03m/s.
EXAMPLE 3 Example 1 was repeated with 6,4% by mass of the FeSi with a particle size of 10,um (ie 1 x 10-5m), but the P95 oil and the Sasolwaks M were replaced by 3,2% by mass of unprocessed petrolatum. The emulsion was sensitive to 0,369 (ie 3,6 x 10-4k9) of PETN in 25mm (ie 2,5 x 10-2m) at 25"C after four months storage at 40"C and after four months storage at ambient temperature. The velocity of detonation was 4,0 X 103m/s. These tests are still in progress so that the maximum storage periods have not yet been established.
EXAMPLE 4 Example 1 was repeated with 3.2% by mass of FeSi having a particle size of 1 0m (ie 1 X 10-5m) and 3.2% by mass of atomised aluminium with a particle size of 50ym (ie 5 x 10-5m). The relative proportions of the other ingredients were adjusted to achieve oxygen balance of the explosive. The emulsion was sensitive to detonation by 0,36g (ie 3,6 x 10-4kg) of PETN in 25 mm (ie 22,5 X 10-2m) at 25"C after three months storage at ambient temperature. The velocity of detonation was 4,1 x 103m/s.
As can be seen from the examples, the properties of the explosive according to the invention were found to be comparable with the corresponding control.
FeSi has been used as a fuel in nitroglycerine explosives instead of aluminium but led to increased impact sensitivity. It has also been used partially to replace aluminium in slurry explosives but led to a decrease in storage stability. In contrast, in the emulsion explosives of the present invention, there is no increase in impact sensitivity and storage stability is good.
FeSi is substantially less expensive than aluminium, and does not have to be coated with stearic acid or the like, as in the case of aluminium, for storage stability, leading to further cost reduction. In tests it has been found that the use of FeSi results in a reduction in postdetonation fumes, no ammonia fumes being produced in the field, unlike the use of aluminium.

Claims (17)

1. An explosive in the form of an emulsion which includes a discontinuous'phase which includes an oxidising salt; a continuous phase which includes a fuel which is immiscible with the discontinuous phase; and as a solid fuel component dispersed in the continuous phase, finely divided ferrosilicon (FeSi).
2. An explosive as claimed in Claim 1 wherein the ferrosilicon has a mean particle size of less than 100 microns (kiel X 10-4m).
3. An explosive as claimed in Claim 1 or Claim 2 which includes, in addition to the ferrosilicon, another solid fuel component.
4. An explosive as claimed in any one of Claims 1 to 3, wherein the total solid fuel content makes up from 2 to 14% m/m of the explosive.
5. An explosive as claimed in any one of Claims 1 to 3 wherein the oxidising salt includes a member selected from the group consisting of: alkali metal nitrates, alkali metal perchlorates, alkaline earth metal nitrates, alkaline earth metal perchlorates, ammonium nitrate, ammonium perchlorate, and mixtures of one or more thereof
6. An explosive as claimed in any one of the preceding claims wherein the oxidising salt is present as an aqueous solution.
7. An explosive as claimed in Claim 5, wherein the discontinuous phase includes ammonium nitrate and a compound, which together with the ammonium nitrate, forms a melt which has aa melting point which is lower than that of the ammonium nitrate, the compound being capable of acting as an oxidising salt or fuel.
8. An explosive as claimed in any one of the preceding claims wherein the fuel forms 2 to 25% by mass of the emulsion.
9. An explosive as claimed in any one of the preceding claims, wherein the fuel is organic and non-self-explosive.
10, An explosive as claimed in Claim 9, wherein the fuel includes a member selected from the group consisting of mineral oils, fuel oils, lubricating oils, liquid paraffin, micro-crystalline waxes, paraffin waxes, xylene, petrolatum, toluene, dinitrotoluene, and one or more mixtures thereof.
11. An explosive as claimed in any one of the preceding claims wherein the fuel includes an emulsifier.
1 2. An explosive as claimed in Claim 11 wherein the emulsifier comprises a member selected from the group consisting of sorbitan sesquioleate, sorbitan monooleate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, the mono- and di-glycerides of fat forming fatty acids, soya bean lecithin, derivatives of lanolin, alkyl benzene sulphonates, oleyl acid phosphate, laurylamine acetate, decaglycerol decaoleate, decaglycerol, decastearate, polymeric emulsifiers containing polyethylene glycol backbones and fatty acid side chains, and suitable mixtures of one or more thereof.
1 3. An explosive as claimed in any one of the preceding claims, wherein the density of the emulsion is from 1,30 kg/l to 1,50 kg/l at 25"C.
1 4. An explosive as claimed in any one of Claims 1 to 12, which includes a density reducing agent.
1 5. An explosive as claimed in Claim 14, wherein the density reducing agent comprises micro-balloons.
1 6. An explosive as claimed in Claim 15, wherein the micro-balloons are of glass or a polymeric material and form up to 5% by mass of the emulsion.
17. A new explosive substantially as herein described and exemplified.
GB08329300A 1982-11-04 1983-11-02 Emulsion explosive composition containing ferrosilicon Withdrawn GB2132998A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ZA828101 1982-11-04

Publications (2)

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GB8329300D0 GB8329300D0 (en) 1983-12-07
GB2132998A true GB2132998A (en) 1984-07-18

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AU (1) AU2093983A (en)
GB (1) GB2132998A (en)
ZW (1) ZW23483A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238210A3 (en) * 1986-03-14 1989-05-24 Imperial Chemical Industries Plc Solid explosive composition
EP0598115A4 (en) * 1989-08-23 1993-01-18 Nippon Oils & Fats Co Ltd W/o emulsion explosive composition.

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1216229A (en) * 1967-06-02 1970-12-16 Du Pont Improvements in or relating to water-bearing explosives
GB1329512A (en) * 1970-02-17 1973-09-12 Du Pont Water-bearing explosives
GB1335097A (en) * 1970-08-18 1973-10-24 Du Pont Emulsion type blasting agent
GB1536180A (en) * 1976-12-29 1978-12-20 Ici Ltd Slurry explosive composition
GB2004265A (en) * 1977-09-19 1979-03-28 Clay R Blasting composition

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1216229A (en) * 1967-06-02 1970-12-16 Du Pont Improvements in or relating to water-bearing explosives
GB1329512A (en) * 1970-02-17 1973-09-12 Du Pont Water-bearing explosives
GB1335097A (en) * 1970-08-18 1973-10-24 Du Pont Emulsion type blasting agent
GB1536180A (en) * 1976-12-29 1978-12-20 Ici Ltd Slurry explosive composition
GB2004265A (en) * 1977-09-19 1979-03-28 Clay R Blasting composition

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238210A3 (en) * 1986-03-14 1989-05-24 Imperial Chemical Industries Plc Solid explosive composition
EP0598115A4 (en) * 1989-08-23 1993-01-18 Nippon Oils & Fats Co Ltd W/o emulsion explosive composition.

Also Published As

Publication number Publication date
GB8329300D0 (en) 1983-12-07
AU2093983A (en) 1984-05-10
ZW23483A1 (en) 1985-07-12

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