ZA200304735B

ZA200304735B - Free-flowing particulate explosive.

Info

Publication number: ZA200304735B
Application number: ZA200304735A
Authority: ZA
Inventors: Francois Kruger; Lownds Charles Michael; Venter Paul Nicolaas
Original assignee: Sasol Chemical Ind Ltd
Priority date: 2001-05-03
Filing date: 2003-06-19
Publication date: 2004-08-02

Description

FREE-FLOWING PARTICULATE EXPLOSIVE

Field of the Invention ' 5 This invention relates to a water-resistant particulate explosive.

Background to the Invention

The inventors are aware that ammonium nitrate explosive mixtures have been known for many years, and since that time have evolved through various stages.

Porous ammonium nitrate prills first became available to industry in the 1950's and it was soon appreciated that the addition of dry or liquid carbonaceous fuels made the ammonium nitrate into an economical, safe and effective blasting agent. This type of explosive is commonly known as ANFO.

In use, ANFO is most commonly delivered into vertical holes in surface mines by auger.

In underground mining, ANFO is conventionally pneumatically (or blow) loaded into small and intermediate diameter boreholes.

The primary drawback of this prior art material is that it has very little or no water resistance and is difficult or impossible to use in wet environments i.e. it is water sensitive,

The inventors are aware of several patents in the above field and they are noted below, however, the inventors do not admit these patents are prior art to the present invention and these patents are merely discussed below to set the stage for the present invention. it has been known for over 20 years, and is disclosed in US 4,181,546, that ANFO can be waterproofed by mixing it with an adequate amount of a water-resistant fluid. Such explosives are called “Heavy ANFO”. The Heavy ANFO in common use today comprises a mixture of ANFO with a fluid water-in-oil emulsion. In order to adequately coat all the

ANFO particles, more than about 40% of emulsion is required in the Heavy ANFO.

These explosives are most commonly augered into dewatered boreholes. They can be pumped into water-filled holes of the emulsion content of the blend is greater than about 55%. , Thus a known problem with Heavy ANFO explosives is their relative lack of water resistance when the ANFO content exceeds about 60%. There have been previous 40 attempts to remedy this problem. In South African Patent No ZA84/9863 and US Patent . No. 4,615,751 an attempt is made to address the water sensitivity problem by adding an emulsion explosive and a water-resisting compound to the ANFO in an attempt to render it water resistant. This patent discloses and claims an explosive which includes 21.4-

50% m/m of an explosive emulsion comprising a discontinuous phase which includes an oxidizing salt and a continuous phase which includes a fuel and which is immiscible with . the discontinuous phase; 50-78.6% m/m ammonium nitrate prills; and a water-resisting agent for inhibiting deterioration of the ammonium nitrate prills in the presence of water with which the explosive may come in contact during use, which agent has the effect of inhibiting access of water to the ammonium nitrate prills, the prills being dispersed in and surrounded by the emulsion and the water-resisting agent.

It is believed that both of the products described in ZA84/9863 and in US 4,181,546 are rarely used in smail diameter bore holes, appear not to be cap sensitive, are not particulate explosives and would be difficult if not impossible to be pneumatically loaded into holes by conventional pneumatic loading equipment.

In US 4,585,496 it is disclosed that particulate explosives can be prepared from blends of ammonium nitrate prills or ANFO, and a fluid, wherein the fluid is either a slurry or a water-in-oil emulsion. The object of this invention is to provide a higher density explosive than ANFO in a borehole after pneumatic loading. In order to maintain a granular and free-flowing nature of the explosive composition, the amount of fluid added is less than about 25% for the slurry or less than about 18% for the emulsion. In both cases, the amount of fluid added is insufficient to provide a water-resistant coating for the prills. This granular explosive is not claimed to be water-resistant and would not be expected to exhibit any degree of water resistance. It's use is thus restricted to the dry blasting conditions to which ANFO is restricted.

In US 6,113,714 another attempt at solving the water sensitivity of this type of expiosive is disclosed. This patent discloses that by adding water resisting agents such as dry powders at the blast hole shortly before the hole is filled with the blasting material the water resistance problem may be at least partially alleviated. It is believed that this approach is rarely used in small diameter bore holes, in part because of separation of the ANFO and the water-resisting additives during pneumatic loading.

Thus, the inventors have identified a need for a particulate explosive which can be prepared as such in a factory, stored as such, and transported as such to it's place of use, and which has water tolerance while being able to be pneumatically loaded into boreholes using conventional apparatus without any separation of the explosives into its constituent parts. Further, it would be advantageous if such a particulate explosive was also cap sensitive and could be used in small diameter boreholes.

©. WO 02/090296 PCT/ZA02/00065 . Summary of the Invention

The invention provides a free flowing particulate explosive composition based on a particulate solid oxidiser which is rendered water resistant by the inclusion of a water- resisting emulsion including one or more hydrophobic and, optionally one or more water binding agent.

The invention extends to a free-flowing particulate explosive comprising - 20% to 90% by mass of a particulate solid oxidiser; and - 10% to 80% by mass, of a water-resisting emulsion, said emulsion having non-stick coating properties when at least partially coating the particles of said oxidiser thereby rendering said particles free-flowing.

In this specification, unless the context clearly indicates to the contrary, the term non- stick is to be understood to mean that particles coated with the emulsion do not stick to each other i.e. no or reduced cohesion, as well as that the particles do not stick to packaging material such as bags and boxes i.e. no or reduced adhesion, thereby rendering the explosive free-flowing.

Said explosive may be water-resistant after consolidation.

The consolidation may be by means of compression in a closed cylindrical space, such as a borehole or test pipe, by pneumatically loading said explosive into the space. The test pipe may be the product pipe of the water resistant detonation test of the examples.

In one embodiment the particulate solid oxidiser is encapsulated in said emulsion while maintaining the flowability of the encapsulated particles.

Said emulsion may comprise of - a discontinuous phase which includes one or more oxidising salts; and - a continuous phase, which includes one or more fuels and one or more emulsifiers, and which is immiscible with the discontinuous phase.

The solid oxidiser may be a porous prill or granule. . The prill or granule may contain hollow microballoons. However, the solid oxidiser may be substantially voidless i.e. without hollow microballoons. 40 ! The oxidising salt of said emulsion may comprise an aqueous solution of one or more salts selected from the group which consists of the nitrates, chlorates and perchlorates of ammonium, alkali metal and alkaline earth metals, or mixtures thereof. The oxidising salt may comprise an aqueous solution of one or more salts selected from the group which consists of ammonium nitrate, sodium nitrate, and calcium nitrate. However, the oxidising salt may comprise a melt of one or more salts selected from the group which consists of the nitrates, chlorates and perchlorates of ammonium, alkali metal and alkaline earth metals, or mixtures thereof. The oxidising salt may comprise a melt of one or more salts selected from the group which consists of ammonium nitrate, sodium nitrate, and calcium nitrate.

The continuous phase may comprise of fuel selected from the group consisting of hydrocarbons, halogenated hydrocarbons, silicone oils, or mixtures thereof, mineral oils, fuel oils, lubricating oils, liquid paraffin, nitro-paraffin, microcrystalline waxes, PEG waxes, paraffin waxes, nitro-paraffin wax, xylene, petrolatum, toluene, dinitrotoluene, silicone oil, polyester, hydroxy-terminated polybutadiene, polymers, polyolefins and derivatives thereof, or mixtures of two or more of the aforegoing.

The fuel may be a hydrocarbon wax with a melting point of between 30°C and150°C.

The fuel may be a hydrocarbon wax with a melting point of between 70°C and 90°C.

Atleast one of the fuels may be cross-linked.

The fuel may comprise an emulsifier selected from the group consisting of fatty acid esters, polymeric emulsifiers, or any emulsifiers known in the art.

The emulsifier may be polyisobutylene succinic anhydride, derivative thereof, and analogues thereof.

A fuel may be added to the solid oxidiser, which fuel is selected from the group consisting of tall oil, mineral oil, paraffin, nitro-paraffin, diesel fuels, vegetable oils, used engine oil, guar gums, polyacrylamides, xantham gum, locust bean gum, chemically modified guar gum, galactomannan gum, pre-hydrolysed starches, carboxy methyl cellulose, polyacrylate esters, polyacrylic acid, derivatives, and mixtures thereof.

Said emulsion may comprise 4% to 30% fuel as continuous phase and 70% to 96% oxidiser as discontinuous phase.

The density of said emulsion may be reduced by adding one or more substances selected from the group consisting of plastic microspheres, glass microspheres, and other density-reducing agents. 40

A particulate solid material which affects the energy or reactivity of the explosive may be added to the explosive prior to or during the coating process. The particulate solid material may be aluminium.

! 0 . The explosive particles may be coated with a suitable parting agent including talc, anthracite, stearates, silicates, kaolin, plastic microspheres, glass microspheres, or mixtures thereof, to assist in the free-flowing properties of the explosive and to reduce ’ 5 agglomeration during storage.

The explosive composition may be a cap-sensitive free flowing particulate explosive composition including ammonium nitrate prills and having said emulsion coating which is chosen to prevent cohesion and therefore permit free flowing of the coated particles. 10

In one embodiment solid oxidizer, which may be porous prill ammonium nitrate (PPAN), is encapsulated in a hydrophobic solid wax emulsion composition consisting of a discontinuous phase which includes an oxidising salt, typically ammonium nitrate, or salt mixtures and a continuous phase which includes a fuel and emulsifier which is 15 immiscible with the discontinuous phase.

A water binding agent for inhibiting deterioration of the particulate oxidizer in the presence of water by drawing water into said substance may be distributed into and/or onto the solid oxidizer and/or the emulsion coating the particulate oxidizer. 20

The water binding agent may be a gelling agent which gels in the presence of free water

The water binding agent may be selected from guar gum, polyacrylamide, xantham gum, locust bean gum, chemically modified guar gum, galactomannan gum, pre-hydrolysed 25 starch, carboxymethylcellulose, polyacrylate ester, polyacrylic acid, derivatives, and mixtures thereof.

The fuel content of the explosive may be adjusted, for example by adding an acceptable fuel oil to the solid oxidizer thereby to oxygen balance the resultant explosive. 30

The oil adjustment may conveniently take place before the solid oxidizer is coated in the emulsion.

The water binding agent and the emulsion have the effect of inhibiting access of water to 35 the solid oxidizer thereby inhibiting the solid oxidizer from dissolving in the water.

The emulsion also provides the particulate explosive with a higher particle density and a . higher bulk density than conventional ANFO and thus produce higher in-hole densities after pneumatic loading. 40 ’ The explosive composition of the invention typically has the following components: a. Emulsion (Hydrophobic Agent):

4% to 30% m/m of a fuel phase, as a continuous phase, including an organic fuel, being for example selected from the group including hydrocarbons, halogenated hydrocarbons, silicone oils or mixtures thereof, mineral oils, fuel oils, lubricating oils, liquid paraffin, nitro-paraffin, microcrystalline waxes, PEG waxes, paraffin waxes, nitro-paraffin waxes xylene, petrolatum, toluene, dinitrotoluene, silicone oil, poly-olefins and derivatives thereof or mixtures of two or more thereof. The fuel may contain 1% to 4% of any suitable emulsifier or mixtures of emulsifiers, preferably emulsifiers of the polymeric kind and more preferably of the polyisobutylene succinic anhydride derivative type.

The fuel phase typically includes one or more hardening agents selected from waxes having a softening point of from 30°C to 150°C, usually from 50°C to 100°C; and a needle penetration hardness of 0.0mm to 5.0mm (ASTM D1321- 86). The fuel phase may contain a cross-linkable organic material in addition to or instead of the wax.

These properties at least in part provide the particulate explosive with water resistance and its granular, free-flowing property by preventing cohesion amongst the coated prills. 70% to 96% m/m of an oxidizer phase, as a discontinuous phase, selected from one or more alkali metal nitrates, alkali metal perchlorates, alkaline earth metal nitrates, alkaline earth metal perchlorates, most preferably ammonium nitrate, sodium nitrate, ammonium perchlorate, and mixtures of two or more thereof. The oxidising salt may be present as an aqueous solution. The oxidizer may contain 1% to 30% water.

Additives, such as from 0% to 4% micro-spheres of the glass or plastic type, with a particle size distribution of Tum to 1000um and mixtures of two or more thereof may then be added to the emulsion as sensitizer and /or density reducing agent.

Other additives may be added to enhance certain properties of the particulate explosive like aluminium, aluminium oxides, thermite, magnetite, hematite, iron oxide, sulfur, carbonaceous materials such as coke, charcoal, carbon black, anthracite and/or mixtures of two or more thereof.

The emulsion may have the following properties: - A softening point between 30°C and 150°C, typically from 50°C to 100°C; and 40 - A needle penetration hardness of 0.0mm to 5.0mm (ASTM D1321-86 ) b. Solid Oxidizer, Fuel and Additives:

The particulate solid oxidizer having from 90% to 100%, prills, granules or . crystals of high or low density and of high or low porosity and containing nitrates and/or perchlorates of ammonia and/or alkali and/or alkaline earth and/or mixtures of two or more thereof, 0% to 10% of one or more hydrophilic substance * 5 selected from guar gums, polyacrylamides, xantham gum, locust bean gum, chemically modified guar gum, galactomannan gum, pre-hydrolysed starches, carboxy methyl cellulose, polyacrylate esters, polyacrylic acid derivatives in conjunction with or without cross-linking agents, and mixtures of two or more thereof and/or 0% to 6% of one or more fuel selected from hydrocarbons, halogenated hydrocarbons, silicone oils and mixtures thereof, selected from mineral oils, fuel oils, lubricating oils, liquid paraffin, nitro-paraffin, ” microcrystalline waxes, nitro-paraffin waxes, PEG waxes, paraffin waxes, xylene, petrolatum, toluene, dinitrotoluene, silicone oil and mixtures of two or more thereof.

The particulate oxidiser is then encapsulated by coating with 10% to 80% m/m, calculated on the total mass of the emulsion and the particulate oxidizer, of the above mentioned emulsion using equipment known in the coating art. The particulate oxidizer can be in the form of flakes, granules, prills and/or mixtures of two or more thereof.

Optionally, the particles of the explosive composition may be coated with 0% to 4% m/m, on a total mass basis, of a parting agent selected from talc, kaolin, alkaline earth metal : silicates, earth metal silicates and Silicone oils and mixtures of two or more thereof and to assist in the free flowing and pneumatic loading of the product, 0% to 2% m/m micro- sphere of the glass or plastic type, with a particle size distribution of 1um to 1000pm and mixtures of two or more thereof, can be added.

The explosive composition particles of the present invention may be packed in bags or boxes and pneumatically loaded at the mine into small diameter bore holes (20mm to 75mm in diameter) under extreme wet conditions with conventional pneumatic loading equipment.

Examples of Explosive Compositions of the Invention.

The examples that follow are intended to serve as example only of how the invention is to be performed and are not intended to limit the scope of the invention in any way. ) : Example 1 40 A particulate free flowing water-resistant explosive composition was prepared including a ’ hydrophobic emulsion and a solid oxidiser:

Emulsion: wm)

Wax (Paraflint C80) 13.84

Emulsifier (Viscotech series) 09]

Co-emulsifier(Viscotech series) 73.80 10.88

Plastic Micro-spheres

Oxidizer:

LT % (mm)

Porous prilled ammonium 93.63 nitrate

Polyacrylamide (Magnafloc 1.00 110L)

Guar gum (Jaguar series)

Explosive Emulsion(Hydrophobic Agent)

The emulsion (Hydrophobic Agent) to encapsulate by coating the solid oxidizer, was prepared as follows: (a) The discontinuous phase consisting of the ammonium nitrate and water, was heated to a temperature of 90°C to form a solution.: (b) The continuous phase consisting of wax, emulsifier and co-emulsifier was heated to 100°C. (c) The oxidising salt solution was added to the continuous phase during vigorous stirring to provide an explosive emulsion having a viscosity of + 15000 cP Brookfield #3 spindle @ 10 rpm at 100°C. Upon cooling to below 60°C, the emulsion had a solid wax consistency. (d) A density reducing agent of the plastic micro sphere type was added to the emulsion while it was still hot. (e) The emulsion was kept at 100°C until it was ready to coat the solid oxidizer phase.

Solid Oxidizer Phase: (a) The solid oxidizer in this case EXPAN™100 was pre heated to 90°C and the polyacrylamide and mineral oil was slowly added and pre-mixed, the guar gum was then added and properly mixed for 120 seconds. These additives were thus dispersed over the surface of the solid oxidizer. (b) The solid oxidizer phase was preheated and kept at 90°C until it was ready to be mixed with the hydrophobic agent.

Water Resistant Particulate Explosive Composition: (a) The solid oxidizer EXPAN™100 (porous ammonium nitrate prills) was then encapsulated by coating with the hydrophobic agent, (the above mentioned emulsion) in the ratio, 75:25 m/m, prills to emulsion by slowly pouring the emulsion onto the prills with gentle mixing to produce a water-resistant particulate explosive product.

The resultant product was then dusted with 1.0% parting agent and 0.05% plastic micro balloons to form a free flowing particulate explosive material with a coating thickness of up to 1.5mm and particle size of between 1mm — 4mm in diameter. This explosive was pneumatically loaded into pipes and subjected to the water-resistant and detonation tests described below, with satisfactory results.

Example 2

A particulate free flowing water-resistant explosive composition was prepared including a hydrophobic emulsion and a solid oxidiser:

Emulsion: 1% (wm)

Wax (Parafiint C80) 13.00

Emulsifier (Viscotech series) 09

Co-emulsifier(Viscotech series) 68.80 water | 86 . Sodium nitrate HEY

Oxidizer : %(mm)

SPAN

Explosive Emulsion(Hydrophobic Agent)

The emulsion of this example (Hydrophobic Agent) to encapsulate by coating the solid oxidizer was prepared using the above formulation and the methods of example 1.

The resulting emulsion had a viscosity of £ 5000 cP Brookfield #3 spindle @ 10 rpm at 100°C and a solid wax consistency at below 60°C.

The emulsion was kept at 100°C until it was ready to coat the solid oxidizer phase.

Solid Oxidizer Phase: (a) The solid oxidizer in this case EXPAN™100 was pre heated to 90°C and the mineral oil and polyacrylamide was slowly added and mixed for 120 seconds. (b) The solid oxidizer phase was kept at 90°C until it was ready to be mixed with the hydrophobic agent.

Water Resistant Particulate Explosive Composition: (b) The solid oxidizer EXPAN™100 (porous ammonium nitrate prills) was then coated with the hydrophobic agent, (the above mentioned emulsion) in the ratio 45:55 m/m, prills to emulsion as described in example 1 to produce a water- resistant particulate explosive product.

The resultant product was then dusted with 0.02% plastic micro balloons to form a free flowing particulate with a coating thickness of up to 1.5mm and particle size of between 1mm — 4mm in diameter that can be compacted to a homogeneous explosives column when pneumatically loaded with conventional pneumatic loading equipment.

Example 3

A particulate free flowing water-resistant explosive composition was prepared including a hydrophobic emulsion and a solid oxidiser: 40

Emulsion: 0 T %(mm . Wax (Paraflint C80) 13.00

Emulsifier (Viscotech series) 09

Co-emulsifier(Viscotech series) 68.80

Water ~~ |] 86

Sodium nitrate EY

Oxidizer 1 %(mm)

PPAN

Mineral Oil

Polyacrylamide

Explosive Emulsion (Hydrophobic Agent)

The resulting emulsion had a viscosity of + 5000 cP Brookfield #3 spindle @ 10 rpm at 100°C and a solid wax consistency at below 60°C.

Solid Oxidizer Phase: (a) The solid oxidizer in this case EXPAN™100 was pre heated to 90°C and the mineral oil was slowly added and mixed for 120 seconds. (b) The solid oxidizer phase was kept at 90°C until it was ready to be mixed with the hydrophobic agent.

Water Resistant Particulate Explosive Composition: (c) The solid oxidizer EXPAN ™100 (porous ammonium nitrate prills) was then coated with the hydrophobic agent, (the above mentioned emulsion) in the ratio 45:55 m/m, prills to emulsion as described in example 1 to produce a water- resistant particulate explosive product.

The table below shows several explosive compositions prepared in accordance with the invention.

Table 1 Examples of Water Resistant Particulate Explosives Compositions % Particulate Standard 1 2 3 4 5 6 7 8

Explosive

Composition

Fuel (E) 3.69 4.40 3.67 3.67 4.38 2.90 3.64 7.70

Oxidizer 22.00 21.90 18.25 18.25 21.72 14.34 18.03 42.57

Water 3.84 3.23 2.69 2.69 3.22 2.13 2.68 4.71

Micro-spheres 0.15 0.15 0.12 0.12 0.17 0.12 0.14 0.00

PPAN 94.3 64.25 64.25 69.49 68.78 64.34 73.61 69.34 44.32

Fuel (P) 5.7 1.04 1.04 0.74 1.48 1.40 1.61 1.13 0.34

Polyacrylamide 1.04 0.74 1.40 1.13 0.34

Water 2.94 3.98 3.24 3.96 2.33 4.25 2.87 0.00

Resisting agent

Parting agent 1.00 1.00 1.00 1.00 . 1.00 1.00 1.00 0.00

Micro-spheres 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.02

Total 100 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

Water Resistance0 >16 hours >16 hours >16 hours >16 hours >16 hours>16 hours >16 hours >16 hours

Emulsion

Softening Point - 70°C 75°C 70°C 80°C 70°C 65°C 70°C 80°C

Detonation Test Fail Pass Pass Pass Pass Pass Pass Pass

Pass

Fuel (E): The fuel component of the emulsion

Fuel (P): The fuel component added to the solid oxidiser

% Particulate Standard 9 10 11 12 13

Explosive ‘ Composition

Fuel (E) 8.40 5.94 5.79 8.07 7.87

Oxidizer 46.44 48.65 47.43 44.59 64.54

Water 5.16 4.81 4.40 4.96 6.37

Micro-spheres 0.00 0.00 0.00 0.00 0.40

PPAN 94.3 39.38 38.98 38.98 38.98 19.8

Fuel (P) 57 0.60 0.60 0.60 0.60 0.00

Polyacrylamide 0.00 0.00 0.00 0.00 0.00

Water 0.00 0.00 0.00 0.00 0.00

Resisting agent

Aluminium 0.00 0.00 1.78 1.78 0.00

Parting agent 0.00 1.00 1.00 1.00 1.00

Micro-spheres 0.02 0.02 0.02 0.02 0.02

Total 100 100.00 100.00 100.00 100.00 100.00

Water Resistance 0 >16 hours >16 hours >16 hours >16 hours >16 hours

Emulsion

Softening Point - 80°C 70°C 70°C 80°C 70°C

Detonation Test Fail Pass Pass Pass Pass Pass

Fuel (E): The fuel component of the emulsion

Fuel (P): The fuel component added to the solid oxidiser

The particulate explosives were tested for water-resistance using the test method described below.

Water Resistance Test 1 Water Resistant Visual Test 1.1 Product Pipe Preparation:

N 1.1.1 Cut a transparent pipe of 26mm in diameter into 1000mm iong sections. 1.1.2 Seal one end of the pipe with an end-cap. Leave the other end of the pipe open.

Claims

1. A free-flowing particulate explosive comprising - 20% to 90% by mass of a particulate solid oxidiser; and - 10% to 80% by mass, of a water-resisting emulsion, said emulsion having non-stick coating properties when at least partially coating the particles of said oxidiser thereby rendering said particles free-flowing.

2. A free-flowing particulate explosive as claimed in claim 1, said explosive being water-resistant after consolidation.

3. An explosive as claimed in claim 1 or claim 2, wherein said emulsion comprises of - a discontinuous phase which includes one or more oxidising salts; and - a continuous phase, which includes one or more fuels and one or more emulsifiers, and which is immiscible with the discontinuous phase.

4. An explosive as claimed in any one of the preceding claims, wherein the solid oxidiser is a porous prill or granule.

5. An explosive as claimed in claim 4, wherein the prill or granule contains hollow microballoons.

6. An explosive as claimed in any one of claims 1 to claim 3, wherein the solid oxidiser is substantially voidless.

7. An explosive as claimed in any one of the preceding claims, wherein the solid oxidiser is ammonium nitrate.

8. An explosive as claimed in any one of claims 3 to 7, wherein the oxidising salt comprises an aqueous solution of one or more salts selected from the group which consists of the nitrates, chlorates and perchlorates of ammonium, alkali metal and alkaline earth metals, or mixtures thereof.

9. An explosive as claimed in claim 8, wherein the oxidising salt comprises an aqueous solution of one or more salts selected from the group which consists of ammonium nitrate, sodium nitrate, and calcium nitrate.

10. An explosive as claimed in any one of claims 3 to 7, wherein the oxidising salt comprises a melt of one or more salts selected from the group which consists of the nitrates, chlorates and perchlorates of ammonium, alkali metal and alkaline earth metals, or mixtures thereof.

11. An explosive as claimed in claim 8, wherein the oxidising salt comprises a melt of one or more salts selected from the group which consists of ammonium nitrate, sodium nitrate, and calcium nitrate.

D

. N ~ WO 02/090296 PCT/ZA02/00065 “

12. An explosive as claimed in any one of claims 3 to 11, wherein the continuous phase comprises of fuel selected from the group consisting of hydrocarbons,

. halogenated hydrocarbons, silicone oils, or mixtures thereof, mineral oils, fuel oils, lubricating oils, liquid paraffin, nitro-paraffin, microcrystalline waxes, PEG waxes, paraffin waxes, nitro-paraffin wax, xylene, petrolatum, toluene, dinitrotoluene, silicone oil, polyester, hydroxy-terminated polybutadiene, polymers, poly-olefins and derivatives thereof, or mixtures of two or more of the aforegoing.

13. An explosive as claimed in claim 12, wherein the fuel is a hydrocarbon wax with a melting point of between 30°C and150°C.

14. An explosive as claimed in claim 13, wherein the fuel is a hydrocarbon wax with a melting point of between 70°C and 90°C.

15. An explosive as claimed in any one of claims 12 to 14, wherein at least one of the fuels is cross-linked.

16. An explosive as claimed in any one of claims 3 to 15, wherein the fuel comprises an emulsifier selected from the group consisting of fatty acid esters, polymeric emulsifiers, or any emulsifiers known in the art.

17. An explosive as claimed in claim 16, wherein the emulsifier is polyisobutylene succinic anhydride, derivative thereof, and analogues thereof.

18. An explosive as claimed in any one of the preceding claims, wherein a fuel is added to the solid oxidiser, which fuel is selected from the group consisting of tall oil, mineral oil, paraffin, nitro-paraffin, diesel fuels, vegetable oils, used engine oil, guar gums, polyacrylamides, xantham gum, locust bean gum, chemically modified guar gum, galactomannan gum, pre-hydrolysed starches, carboxy methyl cellulose, polyacrylate esters, polyacrylic acid, derivatives, and mixtures thereof.

19. An explosive as claimed in any one of the preceding claims, wherein said emulsion comprises 4% to 30% fuel as continuous phase and 70% to 96% oxidiser as discontinuous phase.

20. An explosive as claimed in any one of the preceding claims, wherein the density of the emulsion is reduced by adding one or more substances selected from the group consisting of plastic microspheres, glass microspheres, and other density- reducing agents.

21. An explosive as claimed in claim any one of the preceding claims, wherein a particulate solid material which affects the energy or reactivity of the explosive is added to the explosive prior to or during the coating process. ;

22. An explosive as claimed in claim 21, in which the particulate solid material is aluminium. 40

23. An explosive as claimed in any one of the preceding claims, wherein a water binding agent for inhibiting deterioration of the particulate oxidizer in the presence of water by drawing water into said substance is distributed into and/or onto the solid oxidizer and/or the emulsion coating the particulate oxidizer.

AMENDED SHEET F344 — National Phase amendment

24. An explosive as claimed in claim 23, wherein the water binding agent is a gelling agent which gels in the presence of free water.

25. An explosive as claimed in claim 23 or claim 24, wherein the water binding agent is selected from guar gum, polyacrylamide, xantham gum, locust bean gum, chemically modified guar gum, galactomannan gum, pre-hydrolysed starch, carboxymethylcellulose, polyacrylate ester, polyacrylic acid, derivatives, and mixtures thereof.

26. An explosive as claimed in any one of the preceding claims, wherein the explosive particles are coated with a suitable parting agent including talc, anthracite, stearates, silicates, kaolin, plastic microspheres, glass microspheres, or mixtures thereof, to assist in the free-flowing properties of the explosive.

27. A free-flowing particulate explosive as claimed in claim 1, substantially as herein described and exemplified.

28. Anew free-flowing particulate explosive, substantially as herein described.