NZ228181A - Water-in-oil explosive composition with a viscosity parameter - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £28181 2 2 8 1 8 1 Priority Date(s): X .2} ,?.BB ^ I ; Compif»*o Spsci^c-atton Filed: /.~.v2?.r.£i£j Class: (5),.„CO.0?.(5.3i|l^)^ ...C.O.Gj.^^/oQ <**\ j Publication Date: .^..^..9.^.9..!?.?.!, P.O. Journal, No: NO DRAWINGS NEW ZEALAND PATENTS ACT, 1953 No.: Date: o COMPLETE SPECIFICATION EXPLOSIVE COMPOSITION ?We, id AUSTRALIA OPERATIONS PROPRIETARY LIMITED a Company incorporated under the laws of the State of Victoria of 1 Nicholson Street, Melbourne, Victoria 3001, Australia / H h ' c '•, hereby declare the invention for which-*i-/ we pray that a^atent may be granted to us. and the method by which it is to b« xTfeafjarmed. ~,'i to be particularly described in and by the following state^iftjint: - - 1 - (followed byjsage la) 228 18 1 - kx_- The present Invention relates to an explosive composition and 1n particular to such a composition comprising a blend of an emulsion explosive and solid ammonium nitrate particles.

Emulsion explosive compositions have been widely accepted in the explosives Industry because of their excellent explosive properties and ease of handling.

The emulsion explosive compositions now in common use 1n the industry were first disclosed by Bluhm in United States Patent No. 3 447 978 and comprise as components: (a) a discontinuous aqueous phase comprising discrete droplets of an aqueous solution of Inorganic oxygen-releasing salts; (b) a continuous water-1mmisc1ble organic phase throughout which the droplets are dispersed; (c) an emulslfler which forms an emulsion of the droplets of oxidizer salt solution throughout the continuous organic phase; and (d) a discontinuous gaseous phase. /v o\\. y«r -4 O © O m 228 18 1 More recently explosive compositions which comprise a blend of a water-1n-o1l emulsion and a solid particulate ammonium nitrate (AN) such as ammonium nitrate prills or ammonium nitrate prills coated 5 with fuel oil (referred to as ANFO) have become popular because of the reductions 1n cost due to the Inclusion of a significant proportion, for example, to 50% of AN.

Compositions comprising blends of a water-1n-o1l 10 emulsion and AN (or ANFO) are described, for example, 1n Australian Patent Application No. 29408/71 (Butterworth) and US Patents 3 161 551 (Egly et al), and 4 357 184 (Blnet et al). A serious problem of prior art blends is evident when loading 15 the compositions into wet bore holes.

Although the tendency of the solid AN prill to break up or dissolve 1n water 1s reduced somewhat by the presence of the emulsion component, collar loading of prior art emu 1s1on/pr111 blends Into 20 water-containing bore holes results 1n a significant reduction 1n blast performance.

As a result 1t has hitherto been necessary when loading emulsion/AN blends Into water-containing bore-holes to pump the product to the bottom of the 25 holes using a long delivery hose and to fill the hole by displacing water above the rising explosive co1umn.

This pumping technique however does not allow the rapid loading rates that can be achieved when 30 loading the blends from the top of bore-holes using techniques such as augerlng. Consequently as well as having to accept a slower loading rate in wet bore-holes, frequent users of such exploslves/h'ltve ~ ° / / • ,, , o u m 2 2 8 18 been forced to maintain two sets of equipment for loading bore-holes according to the prevailing weather conditions.

We have now found that by selecting a water-1n-o1l 5 emulsion having a viscosity 1n the range of from 25,000 to 60,000 cps the water resistance of a blend of water-1n-o1l emulsion and solid particulate ammonium nitrate 1s significantly increased while the blend retains a consistency suitable for 10 collar-loading.

Accordingly we provide an explosive composition comprising a blend of 45 to 95% by weight of the composition of a water-1n-oil emulsion comprising a discontinuous aqueous phase comprising at least one 15 oxygen-releasing salt, a continuous water-1mm1scible organic phase and a water-1n-o1l emulsifying agent; and 5 to 55% by weight of the composition of solid particulate ammonium nitrate and wherein the Brookfield Viscosity of the water-1n-o1l emulsion 1s 20 1n the range of from 25,000 to 60,000 cps.

Where used herein the term Brookfield Viscosity refers to the viscosity measured at 60°C using a Brookfield RVT Viscometer No. 7 spindle at 50 rpm. It preferred that the Brookfield Viscosity of the 25 water-in-oil emulsion be 1n the range of 28,000 to 40,000 cps.

A variety of factors influence the viscosity of the emulsion component. For example, the nature of the oil and the water-1n-o1l emulslfler as well as their 30 Interaction. These features may be balanced without undue experimentation to provide a Brookfield Viscosity within the characterising range of frpqj j*"1't">v^ ..v 25,000 to 60,000 cps. m 2 2 8 1 8 vj The emulsion explosive component of the composition may contain adjuvants, for example, void agents such as gas bubbles, porous particles or balloons to reduce the density agent which stabilize void agents and solid particulate material such as carbon or a 1um1n1 urn.

Such materials Influence the viscosity of the composition as does the solid particulate ammonium nitrate and the Brookfield Viscosity of the water-1n-o1l emulsion 1s therefore determined on the water-in-o1l emulsion devoid of adjuvants.

The water-1mm1sclble organic phase component of the water-1n-o1l emulsion of the composition of the invention comprises the continuous "oil" phase of the water-1n-o1l emulsion and 1s the fuel. Examples of organic fuels Include aliphatic, allcycllc and aromatic compounds and mixtures thereof which are 1n the liquid state at the formulation temperature. Suitable organic fuels may be chosen from fuel oil, dlesel oil, furnace oils, distillate, kerosene, naphtha, waxes (eg. mlcrocrysta111ne wax, paraffin wax and slack wax), paraffin oils, benzene, toluene, xylenes, asphaltlc materials, polymeric oils such as the low molecular weight polymers of olefins, animal oils, fish oils, and other mineral, hydrocarbon or fatty oils, and mixtures thereof. Preferred organic fuels are liquid hydrocarbons generally referred to as petroleum distillates such as gasoline, kerosene, fuel oils, furnace oils, and paraffin oils.

Typically, the organic fuel of the continuous phase of the water-1n-o1l emulsion component comprises from 2 to 15% by weight and preferably 3 to 10% by weight of the water-1n-o1l emulsion component of the explosive composition of the Invention. / 22 8 1 8 o - Typically we have found that oils having a viscosity 1n the range of from 4 to 1000 and preferably 6 to 200 centl-stokes are particularly suited to providing a water-1n-o1l emulsion having the 5 characteristic viscosity range of from 25,000 to 60,000 cps.

It 1s particularly preferred that the organic fuel /TTn, of the emulsion component of the compositions of the Invention comprise at least one parafflnlc oil.

Generally it has been the practice 1n the art to use dlesel oil or No. 2 fuel oil 1n the emulsion phase of emuls1on/AN blends. However we have found that the use of parafflnlc oils 1s particularly suited to producing blends having high resistance to water 15 absorption.

The emulsifying agent of the water-1n-o1l emulsion may be selected from the wide range of emulsifying agents known 1n the art. Examples of emulsifying agents inlcude alcohol alkoxylates, phenol 20 alkoxylates, poly(oxyalkylene) glycols, poly(oxyaIkylene) fatty acid esters, amine alkoxylates, fatty acid esters of sorbitol and glycerol, fatty acid salts, sorbltan esters, poly-(oxyalkylene) sorbltan esters, fatty amine 25 alkoxylates, poly(oxyalkylene) glycol esters, fatty acid amides, fatty acid amide alkoxylates, fatty amines, quaternary amines, a 1kyloxazo 11nes, alkenyloxazollnes, Imidazolines, alkyl-sulfonates, alkylarylsulfonates, alkylsulfosucclnates, 30 alkylphosphates, alkenylphosphates, phosphate esters, lecithin, copolymers of poly(oxyalkylene) glycols and poly(12-hydroxystearic acid), and mixtures thereof. Among the preferred emulsifying agents are the 2-alkyl- and 2-alkenyl-4 ,4 1 -bIs ,/v /«: (hydroxymethyl) oxazollne, the fatty acid esters of sorbitol, lecithin, copolymers of poly(oxyalkylene) glycols and poly(12-hydroxystearlc acid), and mixtures thereof, and particularly sorbltan mono-oleate, sorbltan sesqu1o1eate, 2-oleyl- 4,4' -b1s(hydroxymethyl) oxazollne, mixture of sorbltan sesquioleate, lecithin and a copolymer of poly(oxy-alkylene glycol and poly (12-hydroxystearlc acid), polytalk(en)yl]succ1n1c acid and derivatives thereof, and mixtures thereof.

Although a range of emulsifying agents »ay be used 1n preparing compositions of the Invention we have found that a particularly high water resistance 1s provided where the water-1n-oil emulsion component has a viscosity 1n the range of 25,000 to 60,000 cps and the emulsifying agent component comprises a condensation product of an amine and a polyCalk(en)yl]succinic acid and/or anhydride.

Typical examples of condensation products of an amine and poly[alk(en)yl]succin1c acid and/or anhydride may Include esters, imides, amides, and mixtures thereof. Preferably, said emulslfierjjas an average molecular weight in the range 400 to 5000.

In said poly[alk(en)yl]succ1n1c acid-based emulsifler 1t 1s preferred that the hydrocarbo chain 1s derived from polymerization of a mono-olefin and generally the polymer chain will contain from 40 to 500 carbon atoms.

Preferably the poly[alk(en)y1D moiety is derived from olefins containing from 2 to 6 carbon atoms and 1n particular from ethylene, propylene, 1-butene and Isobutene. The emulsifler may be derived from W'.' Jr If* / - 7 - 228181 poly[alk(en)yl]succ1n1c anhydride. Such emulslflers derivatives are disclosed 1n New Zealand Patent No. 211346.

Such derivatives are commercially-available 5 materials which are made by an addition reaction between a polyolefln containing a terminal unsaturated group and malelc anhydride, optionally 1n the presence of a halogen containing catalyst. /~s) The succinic acid or anhydride residue in the above io compounds may be reacted to Introduce a polar group. Generally the said polar group 1s monomerlc although ol1gomer1c groupings containing not more than about 10 repeat units may be employed. Examples of suitable polar groups may include polar groups 15 derived from polyols such as glycerol, pentaerythrltol, and sorbitol or an Internal anhydride thereof (e.g. sorbltan); from amines such as ethylene diamine, tetraethylene trlaalne and dimethylamlnopropylamlne; and from heterocyclics 20 such as oxazoltne or Imidazoline. Suitable oligomerlc groupings Include short-chain poly(oxyethylene) groups (I.e. those containing up (^) to 10 ethylene oxide units).

Formation of emulslflers for use 1n accordance with 25 the invention may be effected by conventional procedures depending upon their chemical natur In order to prepare a derivative of poly(alk (en)yl )succ1n1c acid comprising a polar group derived from an alcohol or amine, the acid groupv^jry e o 30 anhydride thereof can be caused to react with the hydroxyl or amino group by heating the two components together 1n a suitable solvent, 1n the *€' presence of a catalyst if desired. / 2 2 8 1 8 1 The emulslflers may be of a non-Ionic character, but they may alternatively be anionic or catlonlc 1n nature, as, for example, where the hydrophlUc moiety Incorporates the residue of a polyamlne or a 5 heterocyclic compound.

Preferred emulslflers are poly(Isobutylene) succinic anhydride derivatives and most preferably condensates thereof with amines such as ethanolamlne.

Typically, the emulsifying agent component of the composition of the present Invention comprises up to 5% by weight of the emulsion component of the composition. Higher proportions of the emulsifying agent may be used and may serve as a supplemental 15 fuel for the composition but in general it 1s not necessary to add more than 5% by weight of emulsifying agent to achieve the desired effect.

In particular we have found that the use of a poly(1sobutylene)succinn1c anhydride/amine q 20 condensation product 1n combination with a parafflnlc oil 1n the composition of the Invention provides particularly good water resistance and 1s well suited for collar loading Into significant volumes of water. i */ It 1s preferred that the composition of the Invention further comprises voiding agents which may, for example, be 1n the form of fine gas bubbles dispersed through the composition, hollow particles (often referred to as mlcroballoons), porous 30 particles or mixtures thereof.

Techniques for preparing gassed emulsion explosives .... are well known in the art and include mechanical , I, I 2 2 8 1 8 agitation, Injection or bubbling the gas through the composition, or chemical generation of the gas 1 n s1tu.

The preferred process for Introducing a gaseous 5 phase 1s by in situ chemical gassing. Suitable chemicals for the 1n situ generation of gas bubbles Include peroxides, such as hydrogen peroxide, peroxide nitrates, such as sodium nitrite, nitrosamlnes, such as N, N'-d1n1trosopenta-lo methylene tetramlne, alkali metal borohydr1des, such as sodium carbonate. Catalytic agents such as thlocyanate or thiourea may be used to accelerate the decompos1t1 on of a nitrite gassing agent.

Where used the voiding agent may be added before or 15 after the emulsion 1s blended with the ammonium nitrate particles however 1t 1s generally preferred that the voiding agent 1s added to a blend of the emulsion and particles.

Typically the voiding agent comprises 0.05 to 50% by 20 volume of the emulsion explosive component at ambient temperature and pressure. More preferably, where used, the voiding agent 1s present in the range 10 to 30% by volume of the emulsion explosive component and preferably the preferred bubble size 25 of occluded gas 1s below 200 um. More preferably, at least 50% of the gas component will be 1n the form of bubbles or microspheres of 20 to 200 um Internal diameter.

We have found that the presence of a dispersed 30 gaseous phase significantly Improved the water resistance of the composition of the Invention when a gas bubble stabilising agent 1s also present. v\ Hfip.'oo.- \y;J "Of" 228181 Such agents are described 1n our copending Australian patent application No. 40968/65.

Accordingly we further provide an explosive composition comprising from 45 to 95 percent by weight of the total composition of a water-1n-o1l emulsion comprising a discontinuous aqueous phase comprising at least one oxygen-releasing salt, a continuous water Immiscible organic phase, a water-1n-o1l emulsifying agent and at least one agent capable of facilitating the production of gas bubbles 1n the presence of said water Immiscible organic phase; and 5 to 55% by weight of the total composition of solid particulate ammonium nitrate; and wherein said water-1n-o1l emulsifying agent 1s selected from the group consisting of condensation products of an amine and a polyCalk(en)yl]succin1c acid and/or anhydride and mixtures thereof.

The ability of various agents to facilitate the production of small gas bubbles in compositions of the Invention may be determined by a foam stabilization test.

Accordingly in another aspect of the Invention there is provided an explosive composition as hereinbefore described wherein the agent referred to therein 1s characterized further 1n that it has properties which provide a suitable stabilizing effect and which are established by means of a foam stabilization test as hereinafter described.

In the said foam stabilization test 0.2 part by weight of active Ingredient of the cand1datV agent or mixture of agents to be tested 1s added to and mixed with 100 parts by weight of dlesel fuel. 5 ml of the mixture is placed 1n a graduated cylindrical 2 2 8 1 8 1 - n - vessel of 15 mm Internal diameter. The mixture 1s shaken for 15 seconds. A foam forms on the surface of the mixture. The volume <Vg) of the foam 1s measured 5 minutes after the mixture has ceased to be shaken using the graduations on the vessel. The foam volume <vgQ> fs measured again 60 alnutes after the mixture has ceased to be shaken, the vessel and the mixture being kept at a temperature of 18 to 22°C during this period of time. A foam stability parameter 06O/5 1s calculated from the foam volumes by means of the formula 06O/5 = V60 It has been found that those agents or fixtures of agents 1n which the V,. value was equal to or greater than 1 cubic centimetre and had a 0®^/5 equal to or greater than 0.3 Impart the desired gas bubble stabilization effect of this embodiment of the Invention. Hence the foam stabilizing agents preferred for use 1n the compositions of the Invention are those having a V,. value equal to or greater than 1 cubic centimetre and a 06O/^ value equal to or greater than 0.3 as determined by the foam stabilization test hereinbefore described.

The most preferred gas bubble stabilising agents are non-1on1c fluoroalkyl esters such as are available under the trade name "FLUORAD".

Typically when used the gas bubble stabilising agent will be present 1n the range of 0.0001 to 5.0% by weight of the emulsion component of the composition and preferably 1n the range 0.001 to 1%. . / 22 8 1 8 12 i O < /O o Suitable oxygen-releasing salts for use 1n the aqueous phase component of the composition of the present Invention include the alkali and alkaline earth metal nitrates, chlorates and perchlorates, 5 ammonium nitrate, ammonium chlorate, ammonium perchlorate and mixtures therof. The preferred oxygen-releasing salts Include ammonium nitrate, sodium nitrate and calcium nitrate. More preferably the oxygen-releasing salt comprising ammonium 10 nitrate or a mixture of ammonium nitrate and sodium or calcium nitrates.

Typically, the oxygen-releasing salt of the emulsion component of the compositions of the present Invention comprises from 45 to 95% and preferably 15 from 60 to 90% by weight of the total emulsion component of the composition. In compositions wherein the oxygen-releasing salt comprises a mixture of ammonium nitrate and sodium nitrate the preferred composition range for such a blend 1s from 20 5 to 80 parts of sodium nitrate for every 100 parts of ammonium nitrate. Therefore, 1n the preferred compositions of the present invention the oxygen-releasing salt component comprises from 45 to 90% by weight (of the emulsion component) ammonium 25 nitrate or mixtures of from 0 to 40% by weight (of the emulsion component) ammonium nitrate.

Typically, the amount of water employed In the composition of the present Invention 1s in the range of from 1 to 30% by weight of the emulsion 30 component. Preferably the amount employed 1s from 5 to 25%, and more preferably from 6 to 20% by weight of the emulsion component. * j* 1 / s 4. , ''r-'Vi-; P) #1 228 1 8 Preferably the ratio of water-1n-o1l emulslonrsolld particulate ammonium nitrate 1s 1n the range 45:55 to 70:30 and more preferably 45:55 to 60:40.

The term ammonium nitrate particles 1s used herein 5 to encompass compositions of prilled ammonium nitrate which may optionally be coated with a fuel component such as 1n the case of the well known ANFO compos 111ons.

Typically the solid particulate ammonium nitrate 10 will comprise up to 10% w/w of fuel oil with about 6% being preferred. At about 6% the solid particulate ammonium nitrate 1s essentially oxygen-balanced.

In a further embodiment of the Invention there 1s 15 provided a process for preparing the composition hereinbefore described, the process comprises blending from 45 to 95 parts by weight of a water-1n-o1l emulsion and from 5 to 55 parts by weight of a solid particulate ammonium nitrate.

The water-1n-o1l emulsion may be prepared 1n a preliminary procedure comprising : dissolving the oxygen-releasing salt in water at a temperature above the fudge point of the salt solution, preferably at a temperature 1n the range from salt solution; the range from 25 to 110°, to give an aqueous combining the aqueous salt solution, the water-1mm1sc1b1e organic phase and the water-1n-o1l emulsifying agent with rapid 30 mixing to form a water-1n-o1l emulsion; and . y * 1 N / o\ II mixing until the emulsion 1s uniform.

In a preferred embodiment of this process the process further comprises mixing with the emulsion component or one or more constituents thereof a gas bubble stabilising agent and an agent capable of 1n situ generation of gas bubbles.

As hereinbefore discussed the present Invention provides significant advantages 1n loading of water containing bore-holes.

Accordingly we further provide a method of loading a water-containing bore-hole comprising pouring an explosive hereinbefore described Into the water-containing borehole from a position adjacent the collar of the water-containing bore-hole.

By the terra "pouring" 1t 1s meant that the explosive composition 1s released from Its containment or transport means. It is preferred that the explosive composition 1s augered to the collar of the bore-hole and released from a position above the collar.

We also provide a method of blasting 1n a water-containing borehole comprising the steps of loading a water-containing bore-hole as hereinbefore described and detonating the explosive.

It 1s a particular advantage of our compositions that they detonate well even when poured from adjacent the collar of the borehole Into significant depths of water.

Typically compositions of our invention «ay be detonated successfully even when 2 2 8 1 8 1 weight ratio 1s less than 10 and preferably 1n the range of from 1/1 to 6/1.

We also provide a method of blasting comprising detonating an explosive composition as hereinabove described 1n water wherin the explosive/water weight ratio 1s less than 10, preferably in the range of from 1/1 to 6/1. 2 2 8 1 8 1 - 16 o The Invention 1s now demonstrated by but 1n no way limited to the following examples 1n which the term Brookfield viscosity 1s used to refer to measurements carried out at 20°C using a Brookfield viscometer No 7 spindle at 50 rpm.

Example 1 and Comparative Example A The Explosives of Example 1 and Comparative Example A having the compositions as shown 1n Table 1 were prepared according to the following procedure.

TABLE 1 /<7\ o o Example 1 Parts w/w Emulsion component Ammonium nitrate Calcium nitrate Water Acetic acid Distillate (oil) Sorbitan mono-oleate Paraffin (oil) * PIBSA emulsifler Ammonium nitrate particles ANFO 44.7 Gas bubble stabiliser "FLUORAD", 5% solution 22.77 20.32 6.85 0.48 4.2 0.84 1n d1s111 late Gasser agent (solution of 15% sodium nitrite and 30% sodium thlocyanate 1n water) 0.3 0.1 CE A Parts w/w 22.77 20.32 6.85 0.48 4.20 0.84 44.7 0.3 0.1 228181 * The PIBSA emulsifler used was a 1:1 molar condensate of polyisobutylene succinic anhydride and ethano1 amine.

An aqueous solution was prepared by mixing the 5 ammonium nitrate, CN, water and acetic acid. The composition was heated to about 80°C and was added to a rapidly stirred blend of the oil and emulsifler. When addition was complete stirring was continued until the emulsion was uniform (about 60 io seconds).

The ANFO (which comprised particulate amnonlum nitrate on which had been absorbed 6% by weight of fuel oil) was blended with the emulsion and the gas stabilizing agent was then added with mixing, 15 followed by the addition of the gasser solution.

The water-1n-o1l emulsion of the explosive composition of Example 1 prepared according to this process had a Brookfield Viscosity of 30,000 cps.

The water-1n-oil emulsion of the explosive 20 composition of Comparative Example A had a Brookfield Viscosity of 10,000 cps.

The compositions prepared according to the abov^ process were tested as follows:- The explosive (15 kg) 1s poured down a 4 m 25 high (150 mm diameter) artificial borehole t. with a 200 mm diameter package at the bottom containing water (15 kg). The package was removed and excess water poured from the top. The explosive was then primed with 400 g of 30 "ANZOMEX" (trade mark) primer. / / . 228 18 1 The composition of Example 1 successfully detonated on carrying out the above test but the composition of comparative Example A failed to detonate.

Examples 2 and 3 The Explosives of Example 2 and 3 having the compositions as shown 1n Table 2 were prepared ^ according to the following procedure.

TABLE 2 Example 2 Example 3 Parts w/w Parts w/w Emulsion component Ammonium nitrate (chemically pure) 40.66 40.66 Water 10.16 10.16 Paraffin (oil) 2.65 2.65 * PIBSA emulsifler 1.53 1.53 Ammonium nitrate particles ANFO 45.0 45.0 VOIDING MATERIAL ^ 20 "MICR0BALL00NS" 4.0 * The PIBSA emulsifler was the condensation product ^ of'MOBILAD C207" (M0BILAD 1s a trade mark) and v-"/ ethanolamlne 1n 1:1 molar ratio. M0BILAD C207 1s polylsobutylene succinic anhydride 1n a paraffin d11uent.

An aqueous solution was prepared by mixing the ammonium nitrate and water. The composition was heated to about 80°C and was added to a rapidly 30 stirred blend of the oil and emulsifler. When ' ^ c tf 228181 addition was complete stirring was continued until the emulsion was uniform (about 60 seconds).

The ANFO (which comprised particulate ammonium O nitrate on which had been absorbed 6% by weight of fuel oil) was blended with the emulsion and the MICROBALLOONS were then added with mixing.

The water-1n-o1l emulsion of the explosive r^) composition of Examples 2 and 3 had a Brookfield •w Viscosity of 34,560 - 38560 cps.

The compositions of examples 2 and 3 showed little loss of AN from the ANFO when Immersed 1n water.

The composition of example 2 gave 88% of shock when detonated in water-containing bore-holes.

Example 4 The composition of example 2 was prepared and _3 chemically gassed to a density of 1.10 gem The composition of example 4 gave 83% of full energy (shock and bubble) when detonated 1n water-containing bore-holes.

Example 5 O The composition of example 2 was prepared except that the paraffin oil was replaced with Furnace oil.

The composition of example 5 gave 85-90% of full energy (shock and bubble) when detonated iT" - water-containing bore-holes (200 mm d 1 ameter ft //*'

Claims (26)

- 20 - 228181 Example 6 The composition of example 5 was prepared except that the PIBSA emulsifler was replaced with sorbltan mono-oleate. The composition of example 6 gave 81-86% of full energy (shock and bubble) when detonated 1n water-containing bore-holes(200mm diameter). ajgjj-,. WHAT /iV.'Z CLAiM IS: - 21 - •Wve c 1 a4ms de-fH-n 1 ng-t-h-e- 1-nvent 1-on--are- as- f o 11 ows : -

1. An explosive composition comprising a blend of 45 to 95% by weight of the composition of a water-in-o1l emulsion comprising a discontinuous aqueous phase comprising at least one conventional oxygen-releasing salt, a continuous water immiscible organic phase and a water-in-oil emulsifying agent; and 5 to 55% by weight of the composition of solid particulate ammonium nitrate and wherein the Brookfield Viscosity of the water-in-oil emulsion is in the range of from 25,000 to 60,000 cps.

2. An explosive composition according to claim 1 wherein the Brookfield Viscosity of the water-in-oil emulsion is in the range of 28,000 to 40,000 cps.

3. An explosive composition according to either of claims 1 or 2 .wherein the water-1n-oil emulsion comprises a continuous phase having a viscosity in the range of from 4 to 1000 cent1-stokes.

4. An explosive composition according to any one of claims 1 to 3 wherein the water-1n-oil emulsion comprises a continuous phase having a viscosity 1n the range of from 6 to 200 centi-stokes.

5. An explosive composition according to any one of claims 1 to 4 wherein the continuous phase Comprises a paraffinic oil.

6. An explosive composition according to any one of claims 1 to 5 wherein the emulsifying agent comprises a condensation product of an amine and a poly[alk(en)yl3succinic acid and/or anhydride. 228181 - 22 -

7. An explosive composition according to any one of claims 1 to 6 wherein the emulsifying agent comprises a condensation product of ethanolamine and po 1 yisobutylene succinic anhydride.

8. An explosive composition according to any one of claims 1 to 7 wherein the emulsifying agent comprises a condensation product of ethanolamine and polyisobutylene succinic anhydride and wherein the continuous phase comprises a parafflnlc oil.

9. An explosive composition according to any one of claims 1 to 8 wherein the explosive composition further comprises voiding agents selected from the group consisting of fine gas bubbles dispersed through the composition, hollow particles , porous particles or mixtures thereof.

10. An explosive composition according to any one of claims 1 to 9 wherein the explosive composition comprises: from 45 to 95% by weight of a water-in-oil emulsion comprising a discontinuous aqueous phase comprising at least one oxygen-releasing salt, a continuous water-immiscible organic phase, a water-1n-o1l emulsifying agent and at least one agent capable of facilitating the production of gas bubbles in the presence of said water immiscible organic phase; and from 5 to 55% by weight of the total composition of solid particulate ammonium nitrate; and wherein said water-in-oil emulsifying agent 1s selected from the group consisting of the condensation products of an am1n£ and a poly[alk(en)yl]succ1n1c acid and/or janhydrldtT and mixtures thereof. ^ ^ ii 228181 - 23 -

11. An explosive composition according to any one of claims 1 to 10 wherein the explosive composition comprises a water-1n-o1l emulsion and a solid particulate ammonium nitrate 1n the weight ratio, water-in-oil emu 1sion:so 1id particulate ammonium nitrate, 1n the range 45:55 to 70:30.

12. An explosive composition according to any one of claims 1 to 11 wherein the explosive composition comprises a water-in-o1l emulsion and a solid particulate ammonium nitrate 1n the weight ratio, water-in-oil emu 1 si on:so 11d particulate ammonium nitrate, 1n the range 45:55 to 60:40.

13. An explosive composition according to any one of claims 1 to 12 wherein the solid particulate ammonium nitrate comprises fuel oil constituting less than 10% by weight of the solid particulate / ammonium nitrate.

14. An explosive composition according to any one of claims 1 to 13 wherein the solid particulate ammonium nitrate comprises fuel oil constituting 6% by weight of the solid particulate ammonium nitrate.

15. A process for preparing a composition according to any one of claims 1 to 14, which process comprises blending from 45 to 95 parts by weight of a water-1n-o1l emulsion with from 5 to 55 parts by weight of a solid particulate ammonium nitrate. H.Z. P.vTitMT C" F!Cu -8 NOV 1991 r> n r. n »- - 24 - 228181

16. A process according to claim 15 wherein the water-in-oil emulsion is prepared 1n a preliminary procedure comprising : dissolving the oxygen-releasing salt in water at a temperature above the fudge point of the salt Solution, to give an aqueous salt solution; combining the aqueous salt solution, the water-immlscible organic phase and the water-1n-o1l emulsifying agent with rapid mixing to form a water-in-oil emulsion; and mixing until the emulslon'ls uniform.

17. A process according to either of claims 15 or 16 wherein said process further comprises mixing with the emulsion component, or one or more constituents thereof, a gas bubble stabilising agent and an agent capable of 1n situ generation of gas bubbles.

18. A method of loading an explosive composition according to any one of claims 1 to 14 into a water-containing bore-hole comprising pouring said explosive composition into the water-containing borehole from a position adjacent the collar of the water-containing bore-hole.

19. A method of blasting 1n a water-containing borehole comprising the steps of loading an explosive composition according to any one of claims 1 to 14 into a water-containing bore-hole and detonating the explosive. - 25 -

20. A method of blasting in borehole according to claim 19 composition/water weight ratio

21. A method of blasting 1n borehole according to claim 19 composition/water weight ratio from 1/1 to 6/1. ■228181 a water-containing wherein the explosive 1s less than 10. a water-containing wherein the explosive is in the range of

22. An explosive composition as defined in claim 1 substantially as hereinbefore described with reference to any example thereof.

23. A process as defined in claim 15 for preparing an explosive composition substantially as hereinbefore described with reference to any example thereof.

24. A method as defined in claim 18 of loading an explosive composition substantially as hereinbefore described with reference to any example thereof.

25. A method as defined in claim 19 of blasting in a water-containing borehole substantially as hereinbefore described with reference to any example thereof.

26. An explosive composition when prepared by the process as claimed in any one of claims 15 to 17 and 23. !C( /:IU'&T(SAUA oPe-(Z rt i arJ s rrJ.W.i ' y+s/Their authorised Agent ——