CN1368944A - Emulsion explosive - Google Patents

Abstract

An emulsion explosive composition comprising an emulsion explosive and a heave agent. In the context of the present invention, the heave agent is a compound, or mixture of compounds, which is capable of reducing the overall relative effective energy of the emulsion explosive but which, on combustion/detonation, yields gaseous products. Examples of suitable heave agents include inorganic ammonium compounds, organic ammonium compounds, amino acids and non-ammonium containing amides, carbonates and nitrates.

Description

emulsion explosives

The present invention relates to an explosive composition, especially an emulsion explosive composition, a preparation method thereof and a blasting method using the composition.

Explosive compositions release energy in a variety of forms upon detonation. Two of these types of energy release are particularly important to provide control during blasting to ensure the desired load size distribution and dispersion. They are fragmentation energy and heave energy. Fragmentation energy (commonly referred to as impact energy) determines the ability of an explosive composition to fragment the surrounding medium. Blasting of hard media such as rock requires explosive compositions with higher fragmentation energies. The heave energy (commonly referred to as the bubble energy) determines the ability of the explosive composition to move the material around it.

The desired energetic properties of an explosive composition depend on a variety of factors, including the geological conditions of the medium to be blasted. For example, when blasting soft media such as fill or coal, explosive compositions with low fragmentation energy and high heave energy are preferred. If the relative proportion of fragmentation energy is too high, energy will be wasted in generating excess fines close to the blasthole. This particular problem may not be solved simply by reducing the fragmentation energy of the explosive composition, since in conventional explosives this reduction also includes a reduced heave energy. The concomitant localized reduction in heave energy results in less spreading of the load and increases the difficulty and expense of its collection.

In view of this technical background, it would be desirable to provide an explosive composition in which the distribution of fragmentation energy and heave energy is controlled. For example, in view of blasting softer media, it is desirable to provide an explosive composition which reduces fragmentation energy with negligible or minimal loss of heave energy.

In other words, it is desirable to reduce the overall energy of the explosive composition without unduly affecting the associated heave energy. While diluting the explosive composition with an inert diluent or filler may serve this purpose, it is also expected to significantly reduce the volume of gas produced upon detonation of the composition. The reduction in the volume of gas produced will result in a decrease in load spread and increase the difficulty and expense of collection.

The present invention seeks to provide an explosive composition in which the distribution of fragmentation energy and heave energy is controlled. More specifically, the present invention seeks to provide an explosive composition in which the energy of fragmentation can be reduced without significantly affecting the associated heave energy and the volume of gas produced upon detonation. Thus, the explosive compositions of the present invention are adapted to provide the desired balance of fragmentation and heave energies that is readily varied within and between geological formations and blastholes to provide optimum blast performance.

SUMMARY OF THE INVENTION The present invention provides an explosive composition which upon detonation produces a large gas volume regardless of the relative effective energy of the explosive composition. This can be achieved by including certain kinds of additives/chemicals in the composition. This in turn maintains a higher amount of heave energy in the explosive composition.

Furthermore, the present invention can effectively control the heave energy of the explosive composition by slowing down the chemical reaction at the detonation front. The energy release rate of an explosive is controlled by its detonation velocity, which in turn depends on the completeness of the chemical reactions in the explosive's reaction zone. Incomplete reactions behind the blast front of the detonation shock wave decelerate the shock wave. The present invention affects detonation velocity slowing by delaying the chemical interaction between specifically selected additives and the energy-generating decomposition reactions that occur upon detonation of the explosive composition. This delay between the detonation front and the end of the reaction zone makes more energy available for the expansion of the remaining gas behind the C-J plane, ie at the end of the reaction zone. This in turn makes more energy available for expanding the gas, the net result of which is a more efficient medium (eg rock) fracture and uplift process.

Accordingly, the present invention provides an emulsion explosive composition comprising an emulsion explosive and a heave agent. In the context of the present invention, a heave agent is a compound or mixture of compounds which lowers the overall relative effective energy of an emulsion explosive but produces gaseous products upon combustion/explosion. Because of these characteristics, the heave agent is capable of producing a relatively large volume of gas upon detonation of the explosive composition, regardless of the relative effective energy of the composition. In other words, the addition of heave agents reduces the relative effective energy with negligible or minimal adverse effects on the volume of gas produced.

The heave agent can be an oxygen carrier whose negative heat of combustion is, for example, -100 to -500 kcal/kg ( _{H2O liquid} at 0°C) when completely burned. Alternatively, the heave agent may be a weak fuel compared to the fuel component of the emulsion explosive. Preferably, combustion of the heave agent produces a minimal amount of solid residue from combustion. Even better, the heave agent produces only gaseous products when it burns, so that no explosive energy is wasted due to heat retained in the solid combustion by-products. As a weaker fuel, heave agents generally have a low heat of complete combustion, typically from a few hundred to a few thousand kcal/kg, eg 400 to 5000 kcal/kg ( _{H2O liquid} at 0°C).

Many compounds satisfy the above requirements, so they can be used as the healing agent in the present invention. As examples, there may be mentioned inorganic ammonium compounds, organic ammonium compounds, amides, amino acids, carbonates and nitrates. A mixture of any two or more of these compounds may be used as long as the mixture satisfies the above requirements. Useful compounds are commercially available, or can be applied and adapted using known methods. Useful inorganic ammonium compounds include ammonium salts, ammonium double salts, and mixtures thereof. Preferred inorganic ammonium compounds include ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium bicarbonate, ammonium thiosulfate, ammonium thiocyanate, ammonium sulfonate and ammonium phosphate. Preferred double salts include ammonium sulfate nitrate, ammonium phosphate nitrate and calcium ammonium nitrate. A preferred inorganic ammonium-containing double salt is ammonium sulfate nitrate. We have found that fertilizer grade ammonium sulfate nitrate is particularly suitable for use in the present invention.

Ammonium nitrate can be used as a heave agent, but this depends on the characteristics of the emulsion explosive. The latter is necessary for the ammonium nitrate to meet the above-mentioned requirements as a heave agent. Thus, a situation where the addition of ammonium nitrate to an emulsion explosive is not suitable is that the effect of the addition of ammonium nitrate is to increase the relative effective energy of the emulsion explosive.

Solid ammonium nitrate may be used in solid mixture with any other specified heave agents. In this case, the ammonium nitrate-fuel in the emulsion explosive can be replaced by a solid ammonium nitrate heave agent. A combination of solid ammonium nitrate and (other) heave agents is very useful in certain blasting applications. In the case of oxygen negative emulsion explosives, it is preferred to add solid ammonium nitrate in combination with a heave agent. Such a combination is desirable, for example, when the heave agent is highly oxygen negative and needs to be used in larger amounts.

Organic ammonium compounds suitable for use in the present invention include ammonium acetate, ammonium oxalate, ammonium tartrate and ammonium citrate.

Useful carbonates include alkali metal and alkaline earth metal carbonates such as sodium carbonate, barium carbonate and calcium carbonate.

Nitrates suitable for use in the present invention include alkali metal and alkaline earth metal nitrates such as sodium nitrate and calcium nitrate.

Urea and dicyandiamide may be mentioned as suitable amides. When urea is used, it is generally used in an amount of 10-30% by weight, based on the total weight of the composition. The use of this amount of urea is particularly effective in reducing the detonation velocity of the explosive composition while producing large quantities of gas. Also, urea is the preferred heave agent due to its low cost and high effectiveness. Amides such as organic compounds containing a _-CONH2 moiety or derivatives thereof can also be used as useful amides suitable as heave agents.

Amino acids can be used as swelling agents. As examples, mention may be made of glycine, methionine, alanine and lysine. Animal feed grade methionine is preferred due to its lower cost.

The amount of heave agent used in the explosive composition of the present invention is generally greater than 5% by weight. The amount of heave agent can easily be as high as about 60% by weight. However, the heave agent is preferably used in an amount of 20-40% by weight of the explosive composition.

Elevation agents included in the compositions of the present invention are solid, usually in the form of granules/particles. The particle size of the heave agent is usually 1-10 mm diameter. The optimum particle size depends on the size (diameter) of the explosive. Larger diameter heave agent granules are advantageously used in large diameter boreholes, such as those used for blasting fill or coal (150-320mm blasthole). That is to say, the most commonly used particle size is about 1-2mm. Ammonium sulfate nitrate (fertilizer grade) is commercially available with 85% particle size in the range of 2-5 mm with an average particle size of 2.8-3.5 mm.

Explosive emulsions suitable for use in the present invention may be water-in-oil emulsions, melt-in-oil emulsions or melt-in-fuel emulsions. Water-in-oil emulsion explosive compositions were first disclosed by Bluhm in US Pat. phase, the droplets are dispersed throughout the organic phase; and (c) an emulsifier capable of forming an emulsion of droplets of the oxidant salt solution throughout the continuous organic phase. When these types of emulsions contain only very small amounts of water or extraneous water in the discontinuous phase, they are more properly referred to as melt-in-fuel type emulsion explosives.

Suitable oxygen-releasing salts for the aqueous phase of the emulsion include the alkali and alkaline earth metal nitrates, chlorates and perchlorates, ammonium nitrate, ammonium chlorate, ammonium perchlorate and mixtures thereof. Preferred oxygen releasing salts include ammonium nitrate, sodium nitrate and calcium nitrate. More preferably the oxygen releasing salt comprises ammonium nitrate or a mixture of ammonium nitrate and sodium nitrate or calcium nitrate. These salts dissolve and form part of the aqueous phase of the emulsion.

Based on the total amount of the emulsion composition, the content of the oxygen-releasing salt component in the composition of the present invention is generally 45-95% w/w, preferably 60-90% w/w. In compositions wherein the oxygen-releasing salt comprises a mixture of ammonium nitrate and sodium nitrate, the preferred composition range for such mixture is 5-80 parts of sodium nitrate per 100 parts of ammonium nitrate. Thus, in preferred compositions, the oxygen releasing salt component comprises 45-90% w/w (based on the total amount of the emulsion composition) of ammonium nitrate or 0-40% w/w sodium or calcium nitrate and A mixture of 50-90% w/w ammonium nitrate.

Generally, water is used in the compositions of the present invention in an amount of 0-30% w/w of the total emulsion composition. The amount is preferably 4-25% w/w, more preferably 6-20% w/w.

The water-immiscible organic phase in the emulsion compositions of the present invention comprises the continuous "oil" phase of the emulsion composition, which is the fuel. Suitable organic fuels include aliphatic, cycloaliphatic and aromatic compounds and mixtures thereof, which are liquid at the temperature of formulation. Suitable organic fuels may be selected from fuel oils, diesel oils, distillates, furnace oils, kerosene, naphtha, waxes such as microcrystalline waxes, paraffin and oleaginous waxes, paraffin oils, benzene, toluene, xylene, bituminous materials, polymeric Oils such as low molecular weight olefin polymers, animal oils, vegetable oils, fish oils and other mineral, hydrocarbon or fatty oils and mixtures thereof. Preferred organic fuels are liquid hydrocarbons, commonly known as petroleum distillates such as gasoline, kerosene, heating oil and paraffin oil.

Based on the total amount of the composition, the content of the organic fuel or the continuous phase in the emulsion is generally 2-15% w/w, preferably 3-10% w/w.

The emulsifiers in the emulsion compositions of the present invention may comprise emulsifiers selected from the many emulsifiers known in the art for preparing emulsion explosive compositions. The emulsifier used in the emulsion composition of the present invention is particularly preferably one of the well-known emulsifiers based on the reaction product of poly[alkenyl]succinic anhydrides and alkylamines, which include polyisobutylene succinic anhydrides of alkanolamines (PiBSA )derivative. Other suitable emulsifiers for use in the emulsions of the present invention include alcohol alkoxylates phenol 5 alkoxylates, poly(oxyalkylene) glycols, poly(oxyalkylene) fatty acid esters, amine alkoxylates, sorbitol and glycerin Fatty acid esters, fatty acid salts, sorbitan esters, poly(oxyalkylene) sorbitan esters, fatty amine alkoxylates, poly(oxyalkylene) glycol esters, fatty acid amines, fatty acid amide alkoxylates, Aliphatic amines, quaternary amines, alkyloxazolines, alkenyloxazolines, imidazolines, alkylsulfonates, alkylarylsulfonates, alkylsulfosuccinates, alkylarylsulfonic acids Salts, alkyl sulfosuccinates, alkyl phosphates, alkenyl phosphates, phosphoric acid esters, lecithins, copolymers of poly(oxyalkylene) glycols and poly(12-hydroxystearic) acids and mixtures thereof .

Generally, emulsifiers in emulsions comprise up to 5% w/w of the emulsion. Higher proportions of emulsifier can be used and it can be used as a supplementary fuel to the composition, but it is generally not necessary to add more than 5% w/w emulsifier to achieve the desired effect. Stable emulsions can be prepared using lesser amounts of emulsifiers, and for economic reasons it is preferred to keep the amount of emulsifier to the minimum required to form the emulsion. The preferred amount of emulsifier is 0.1-3.0% w/w of the water-in-oil emulsion.

Typically, the emulsion itself is not explosive, and to form an explosive composition, the emulsion must be mixed with a sensitizer such as a spacer that is itself an explosive (eg, trinitrotoluene or nitroglycerin) or a discontinuous phase. Suitable voiding agents include glass microballoons, plastic microballoons, expanded polystyrene beads and air bubbles, including nitrogen bubbles and entrapped air generated in situ by chemical gassing agents.

If desired, in addition to the water-immiscible organic fuel phase, other optional fuel substances, hereinafter referred to as auxiliary fuels, may be added to the emulsion. Examples of such secondary fuels include finely divided solids and water-miscible organic liquids that can be used to partially replace water as a solvent for oxygen-releasing salts or to extend the aqueous solvent for oxygen-releasing salts. Examples of such secondary fuels include finely divided solids and water-miscible organic liquids that can be used to partially replace water as a solvent for oxygen-releasing salts or to extend the aqueous solvent for oxygen-releasing salts. Examples of solid secondary fuels include finely divided materials such as sulfur and carbonaceous materials such as natural pitch, pulverized coke or charcoal, carbon black, sugars such as glucose or dextrose, and plant products such as starch, nut meal, grain Meal and wood pulp. Examples of water-miscible organic liquids include alcohols such as methanol and glycols such as ethylene glycol. Generally, the optional auxiliary fuel component will be present in the compositions of the invention in an amount of 0-30% w/w of the total composition.

Water-in-oil emulsion compositions can be prepared in a number of different ways. A preferred preparation method comprises: dissolving said oxygen-releasing salt in water at a temperature higher than the fudge point of the salt solution, preferably at a temperature of 20-110° C., to obtain an aqueous solution of the salt; Combine the aqueous salt solution, the water-immiscible organic phase, and the emulsifier and mix quickly to form a water-in-oil emulsion; mix until the emulsion is homogeneous.

It is also within the scope of the present invention that other substances or mixtures of substances which are oxygen-releasing salts or which are themselves suitable as explosive materials may be added to the emulsion.

The heave agents used in the practice of this invention are believed to play an important role in the decomposition of emulsion explosives. By way of illustration only, reference is made below to compositions wherein the oxygen releasing salt is ammonium nitrate.

The rate-determining step in the combustion process of emulsion explosives is considered to be the dissociation reaction of ammonium nitrate to ammonia and nitric acid:

NH ₄ NO ₃ ＞NH ₃ +HNO ₃ endothermic (1)

  ＜

The heave agent is believed to inhibit or delay the progress of the above reaction (1) by:

(i) Decomposition occurs, e.g., by a marked shift to the left of the associated dissociation equilibrium, producing excess ammonia,

(NH ₄ ) ₂ C ₂ O ₄ >2NH ₃ +(COOH) ₂ (2)

Ammonium oxalate > ammonia + oxalic acid

(ii) Amides (such as urea, dicyandiamide), amides containing -CONH ₂ , amino acids or other reducing materials are mixed with nitric acid or nitrogen oxides produced during the decomposition of ammonium nitrate in reaction (1). It is believed that unoxidized ammonia accumulates in the reaction zone, thereby inhibiting or delaying the combustion process of reaction (1). In the reaction scheme below, urea is used as an example.

HNO ₃ +CO(NH ₂ )＞CO(NH ₂ ) ₂ HNO ₃ (3)

Nitric acid + urea > urea nitrate

Thus, it is considered that the heave agent acts as a retarder in the decomposition reaction of ammonium nitrate. Reactions (2) and (3) shift the equilibrium of reaction (1) to the left and are therefore thought to control the rate of energy release.

The interaction of the heave agent with the emulsion explosive completes the following reactions:

NH ₄ NO ₃ >2H ₂ O+0.5O ₂ +N ₂ Exothermic (4)

Since excess oxygen is eliminated by reacting with ammonia generated by the decomposition of the retarder in reaction (2), it is considered possible to make reaction (4) proceed in the direction of releasing heat.

2NH ₃ +1.5O ₂ >N ₂ +3H ₂ O exotherm (5)

Even small amounts of combustible substances can affect exothermic decomposition to proceed with the release of considerable amounts of exothermic energy. It is believed that use of ammonium salts of weaker acids, ie ammonium salts with lower dissociation temperatures, facilitates decomposition into gaseous components (ie 2).

Ammonium nitrate is an oxygen positive molecule containing one oxygen atom per molecule, which is in excess (ie 4) of what is required to completely burn its hydrogen atoms. When heat is present, excess oxygen is used to oxidize the hydrogen added to the amino group of the ammonium salt (ie 5). Oxidation of ammonia (in ammonium salts) generates heat which is further required to convert acid residues (in ammonium salts) into gaseous products.

(COOH) ₂ + heat > H ⁺ ₂ + 2COO ^- endothermic (6)

In addition to the above requirements, thermal energy is also required for the dissociation of ammonium nitrate previously into ammonia and nitric acid.

NH ₄ NO ₃ + heat > NH ₃ + HNO ₃ endothermic (1)

The addition of the heave agent according to the invention appears to have a retarding and slightly desensitizing effect on the decomposition process of the explosive. Furthermore, heave agents appear to provide a thermal energy surplus due to the oxidation of amino groups (as shown in reaction (5) above), and a thermal energy deficit due to the dissociation reaction of acid groups (6).

The heave agent is believed to have a significant effect on chemical reactions and thermochemistry. The rate of release of chemical energy is very important in the operation of explosives in breaking up media such as rock. The distribution of energy into fragmentation energy and heave energy determines the ability of the explosive to fragment and move the material around it.

The heave agents used in the practice of this invention effectively control the release of heave energy by slowing down the chemical reaction of the detonation front as shown by reducing the detonation velocity value and extending the length (critical diameter) of the reaction zone. The heave agent can generate a large amount of gas during the detonation process by reacting with the emulsion explosive. A large amount of gas release provides effective blasting. Direct oxidation of fuel oil due to the discontinuous phase of oxygen-releasing salts also produces large quantities of very hot gases, which tend to be very energetic.

Advantageously, the present invention provides a readily variable explosive composition which allows the rate of energy release to be controlled while maintaining high gas production. The compositions of the present invention enable the loading of pre-drilled boreholes with explosive compositions whose energy release rate is specifically selected for each borehole and even the region within each borehole. The use of the variable energy explosives of the present invention provides better control where the earth is broken and can reduce or eliminate back breaks.

By varying the proportion of heave agent added to the explosive composition during manufacture and pumping and/or auguring the explosive composition into the borehole, it is possible to provide explosives with variable energy distribution and energy release rates. Compositions of the invention. Emulsion explosive compositions are usually made by mixing the components with fuel oil in situ using bulk trucks. The on-site manufacture of emulsion explosive compositions is readily applicable to the manufacture of the explosive compositions of the present invention.

An additional storage device can be added to the mobile explosive manufacturing unit, so that the metering rate of the heave agent can be controlled during the process of making the explosive to control the rapid change of the amount of the heave agent. This also allows the composition of the explosive to be easily varied from one blasthole to another, and also to be varied rapidly within any particular blasthole. By producing a suitable energy release even in blastholes, local variations in geology can be easily taken into account.

The compositions of the present invention reduce fines generation, reduce backbreaking, improve formation and placement of rock deposits, thereby providing increased dragline and bucket efficiency, and can reduce or eliminate bullying of the ground. ).

Although the emulsion explosive composition of the present invention can be used as such, these explosives can also be blended with ANFO-based explosives known in the art.

The compositions of the present invention can be readily prepared by combining the heave agents described herein with emulsion explosives. The emulsion can be a prepared batch, or the heave agent can be mixed with the components of the emulsion explosive during the preparation of the emulsion explosive. Mixing can be carried out by a conventional method.

The invention also provides a method of detonation which comprises detonating an explosive composition of the invention. Compositions can be detonated using conventional methods.

The present invention is now illustrated by the following Examples and Comparative Examples.

Example 1

Mix the components listed in the following table in percentage by weight to prepare an emulsion explosive composition with the following formula.

Oxidant solution:

Ammonium nitrate (non-porous) 73.80

Water 18.40

Acetic acid (75%) 0.16

Soda Ash 0.04

Fuel mixture:

Lotion 1.85

Paraffin oil 5.75

This emulsion was sensitized using a gasser (30% w/w sodium nitrite in water). Fertilizer grade ammonium sulfate nitrate (ASN) granules with an average diameter of 2.8-3.5mm were mixed into the sensitized emulsion. The ASN:emulsion mixing ratio and the density of each formulation are listed in the table below. A number of theoretical calculations were performed to evaluate the possible properties of each composition. The results of these calculations for ideal explosive properties using the "Criteria for Ideal Explosives" ("IDEX") are also presented in Table 1.

Table 1

Dynamite Lotion ASN: Explosive Emulsion - IDEX calculation 0/100 20/80 30/70 40/60 50/50 60/40 Density(g/cc) 1.20 1.28 1.32 1.37 1.42 1.48 Gas volume (l/kg) 1100 1080 1070 1060 1040 1020 REE (%) 95 88 85 82 78 73 RBS(%) 143 141 141 140 138 135

REE stands for relative effective energy at a pressure of 100 MPa, which is normalized with respect to ANFO. For ANFO, take REE as 100%.

RBS stands for Relative Bulk Strength, which is normalized to ANFO (whose RBS is 100%). The RBS includes density weighting, which can be calculated by multiplying the REE for a given composition by the factor _dc / _dANFO , where _dc is the density of the composition under consideration and _dANFO is the density of ANFO.

It can be seen that the addition of a heave agent (ammonium sulfate nitrate) reduces the relative effective energy of the composition. However, this reduction involves only a slight reduction in the volume of gas produced. In this way, heave agents can be used to tailor the properties of emulsion explosive compositions. In practice, the relative bulk strength is not substantially affected since the addition of the heave agent increases the density of the composition.

Example 2

A sensitized water-in-oil emulsion was prepared by mixing the ingredients in the weight percents listed below.

Oxidant solution:

Ammonium nitrate 72.80

Sodium Perchlorate 9.00

Water 8.00

Fuel mixture:

Emulsifier 1.60

Paraffin oil 4.60

Sensitizer: 4.00

The resulting emulsion is detonator sensitive.

With one exception, fertilizer grade ASN (average diameter 2.8-3.5 mm) particles were added to this emulsion in the weight ratios listed in the table below. The density of each formulation is also listed in the table below.

Compositions were tested and their detonation velocities were measured as follows. Two lengths of optical fiber with clean cut ends are inserted at a known distance (typically 100 mm) into the explosive being tested in a cardboard tube. The other end of the optical fiber is connected to the terminal of an electronic timer capable of recording the time of the light pulse from the start signal to the stop signal. The fiber optic located in the charge closest to the detonator provides the start signal for the timer and should be connected to terminal 0. The second optical fiber stops the timer and should be connected to terminal 1. A timer records the time of the light pulse from the blast front and displays the time in milliseconds as the blast front passes through the starting and stopping fiber optics. The blast velocity is calculated from the time taken from the blast front through the first optical fiber to the second optical fiber.

A charge of explosives in cardboard tubes of different diameters was detonated. The critical diameter is determined by the minimum charged explosive diameter at which 100% explosive detonation is achieved. Available relative effective energy, available relative bulk strength and gas volume were also calculated.

The results of these tests are listed in Table 2 below.

Table 2 Preparation part number CE1 1 2 3 4 Emulsion (wt%) 100 70 60 50 40 ASN(wt%) - 30 40 50 60 Density(g/cc) 1.10 1.20 1.26 1.32 1.34 VOD(km/s) Diameter of exposed primary explosive charge 19mm 4.65 3.85 3.40 f 25mm 4.95 4.30 3.95 3.60 f 32mm 5.05 4.50 4.20 3.80 3.10 45mm 5.25 4.65 4.45 4.25 3.70 100mm 5.40 4.90 4.80 4.50 4.00 Critical diameter (mm) >8 >12 >16 >18 >25 useful energy REE (%) 103 90 84 79 73 RBS(%) 142 139 135 133 130 Gas volume (l/kg) 1010 987 982 977 973

F - can't explode

Example 3

The components were mixed to prepare an unsensitized water-in-oil emulsion having the composition shown in Example 1 above. The emulsion was sensitized with the gassed solution of Example 1 and the resulting sensitized emulsion had the densities listed in Table 3 below. With one exception, fertilizer grade ASN was added to each formulation as in Example 1. Each composition was tested and REE, RBS and gas volume were calculated. The result is as follows.

table 3 Preparation part number CE2 5 6 7 8 Emulsion (wt%) 100 70 60 50 40 ASN(wt%) - 30 40 50 60 Density(g/cc) 1.12 1.23 1.29 1.33 1.35 VOD(km/s) Diameter of exposed primary explosive charge 28mm 4.95 f 40mm 5.15 4.20 f f f 70mm 5.40 4.80 4.60 3.80 / 100mm 5.50 5.00 4.80 4.40 4.40 152mm 5.65 5.10 5.00 4.60 / Critical diameter (mm) >28 >40 >50 >60 >120 Available Energy: REE (%) 87 78 75 70 65 RBS(%) 121 120 121 117 110 Gas volume (l/kg) 1100 1070 1060 1040 1020

F - can't explode

/- cannot be determined

Example 4

Change the exact formulation of the sensitized emulsion, adjust the degree of outgassing, and repeat the process of Example 3. The results are listed in Table 4 below.

Table 4 Preparation part number CE3 9 10 Emulsion (wt%) 100 80 60 ASN(wt%) - 20 40 Density(g/cc) 1.26 1.31 1.39 VOD(km/s) Diameter of exposed primary explosive charge 70mm f 80mm 4.90 / 90mm 5.40 f 100mm 5.60 4.30 f 125mm 5.80 5.00 3.80 150mm 6.00 5.50 4.10 Critical diameter (mm) >70 >90 >100 Available Energy: REE (%) 100 91 84 RBS(%) 157 149 146 Gas volume (l/kg) 1100 1080 1060

F - can't explode

/- cannot be determined

Example 5

The (unsensitized) emulsion was prepared as in Example 1. With one exception, the emulsions were mixed with a granular mixture comprising ammonium nitrate and urea or ASN (fertilizer grade; average diameter 2.8-3.5 mm) as a healing agent.

Test the prepared explosives according to the above method, and the results are listed in Table 5.

table 5 Preparation part number CE4 CE5 11 12 13 Emulsion (wt%) 100 100 70 60 60 Ammonium nitrate (wt%) - - twenty four - - Urea (wt%) - - 6 - - ASN(wt%) - - - 40 40 Density(g/cc) 1.12 1.26 1.18 1.29 1.39 VOD(km/s) Diameter of exposed primary explosive charge 50mm / / 4.50 4.60 / 70mm 5.40 / 4.60 4.80 / 100mm 5.50 5.60 5.00 5.00 / 150mm 5.65 6.00 5.00 / 4.10 180mm / / / / / Critical diameter (mm) >35 >70 >60 >50 >120 Available Energy: REE (%) 87 100 / 75 84 RBS(%) 121 157 / 121 146 Gas volume (l/kg) 1100 1100 1090 1060 1060

/- cannot be determined

The results of Examples 2-5 can be summarized as follows.

The addition of a heave agent to each composition increases the critical diameter. For example, increasing the amount of heave agent from 30% to 60% by weight in Formulation Nos. 1-4 increased the critical diameter from about 12mm to about 25mm. This effect was also observed in the remaining examples. The critical diameter of a charge of explosive varies with the length of the reaction zone. The length of the reaction zone is very short (2-10 mm) for fast detonating explosives and very long (35-70 mm) for slower detonating primary charges. It has been observed that a significant slowdown of the detonation front reaction makes more energy available for the expansion of the remaining gas behind the C-J plane.

The addition of heave agent significantly decreased REE, and the degree of reduction increased with the increase of heave agent dosage. For example, in formulation numbers 1-4, the REE was 90-73%. However, in these formulations, the gas volume generated remained relatively constant, fluctuating only between 987-973 l/kg. The volume of the gas is indeed not adversely affected to a significant degree. This effect was also consistent in all examples using a heave agent. These results show that, in accordance with the present invention, heave agents can be added to control the explosive properties of the compositions. The RBS value remained unchanged except for the addition of an excess of 60% heave agent. RBS is a function of the density of the composition being tested.

Comparative example 1

Water-in-oil type explosive emulsion was prepared according to Example 2. One exception was the addition of sodium chloride (10-40% through 36 mesh; British Standard Sieve, 10% through 72 mesh; British Standard Sieve) to the emulsion in wt % as listed in the table below. The emulsion was tested and calculated as in the above examples, the results are as follows.

Table 6 Preparation part number CE5 CE6 CE7 CE8 Emulsion (wt%) 100 80 70 50 Sodium chloride (wt%) - 20 30 50 Density(g/cc) 1.10 1.26 1.35 1.45 25mm 4.95 4.75 4.40 3.95 32mm 5.05 4.90 / 4.20 45mm 5.25 4.85 4.75 4.40 100mm 5.40 5.15 5.00 4.60 Critical diameter (mm) >19 >19 >19 >19 Available Energy: REE (%) 103 76 63 39 RBS(%) 142 116 102 71 Gas volume (l/kg) 1010 808 707 506

/- cannot be determined

In the context of the present invention, sodium chloride is an inert diluent/filler. The addition of sodium chloride had no effect on the critical diameter, which remained constant at about 19 mm. Sodium chloride lowers the REE and significantly reduces the volume of gas produced during combustion. For example, the addition of 50% by weight sodium chloride effectively halved the volume of gas generated compared to the unadded emulsion (Formulation CE5). This reduction in gas volume is due to the fact that sodium chloride does not promote the gas evolution upon detonation. This should be compared with the heave agents used in the present invention which lower the REE but have little detrimental effect on the volume of gas produced during combustion. This is because the heave agent helps to improve the efficiency of the detonation process.

Compositions comprising heave agents were also observed to provide cleaner explosions in terms of the detonation smoke produced. This is illustrated by the absence of brown/yellow smoke from detonation upon combustion of Formulations 1-4 (Table 2). Over the larger test site, comparative formulation CE2 produced some yellow smoke, while formulations 5-8 produced white/light gray smoke after detonation. The comparative formulation (CE1 ) produced a slightly odorous yellow/brown color on detonation. The yellow/brown smoke is thought to be caused by less nitrogen oxides. The use of heave agents is believed to provide more complete combustion, resulting in less partially oxidized species. This is another advantage of the invention.

Those skilled in the art will appreciate that the invention described herein is susceptible to changes and modifications other than those specifically described. It should be understood that the present invention includes all such changes and modifications as fall within the spirit and scope of the present invention. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps or features.

Throughout this specification and the following claims, unless the context requires otherwise, the word "comprises" and variations thereof such as "comprises" and "comprises" shall be understood to mean including said one integer or step or group of integers or steps, but does not exclude any other integer or step or group of integers or steps.

Claims (16)

1. emulsion explosive composition, it comprises emulsion explosive and protuberance agent.

2. composition as claimed in claim 1, the agent of wherein swelling have the compound of the oxygen carrier of negative heat when being a kind of perfect combustion, or the fuel that exists in a kind of that produce gaseous product at the blasting explosives composition explosion time and the emulsion explosive weak fuel of comparing.

3. composition as claimed in claim 1 or 2, wherein in the gross weight of composition, the amount of protuberance agent is at least 5 weight %.

4. as the described composition of above-mentioned each claim, the agent of wherein swelling is selected from inorganic ammonium compound, organic ammonium compound, amino acid and does not contain acid amides, carbonate and the nitrate of ammonium.

5. composition as claimed in claim 4, the agent of wherein swelling is a kind of mineral compound, and it is selected from ammonium nitrate, ammonium sulfate, ammonium chloride, volatile salt, bicarbonate of ammonia, ammonium thiosulfate, ammonium thiocyanate, ammonium sulphonate, ammonium phosphate, ammonium sulfate nitrate, phosphoric acid ammonium nitrate and calcium ammonium nitrate.

6. composition as claimed in claim 4, wherein the organic ammonium compound is selected from ammonium acetate, ammonium oxalate, ammonium tartrate and ammonium citrate.

7. composition as claimed in claim 4, wherein carbonate is selected from yellow soda ash, barium carbonate and lime carbonate.

8. composition as claimed in claim 4, wherein nitrate is selected from SODIUMNITRATE and nitrocalcite.

9. composition as claimed in claim 4, wherein acid amides is selected from urea, Dyhard RU 100 and contains-CONH ₂Functional moiety's acid amides, or their derivative.

10. composition as claimed in claim 4, wherein amino acid is selected from glycine, methionine(Met), L-Ala and Methionin.

11. as the described composition of above-mentioned each claim, wherein emulsion explosive is a kind of water-in-oil emulsion, it comprises the water that contains oxygen release salt and contains fuel and organic phase water immiscibility.

12. make the emulsion explosive method for compositions for one kind, it comprises sneaks into the protuberance agent in the emulsion explosive.

13. method as claimed in claim 12 swells wherein in agent such as claim 2 and 4 to 10 that each defines.

14. as claim 12 or 13 described methods, wherein in the gross weight of composition, the amount of sneaking into the protuberance agent in the emulsion explosive is at least 5 weight %.

15. as each described method in the claim 12 to 14, wherein emulsion explosive as defined in claim 11.

16. the method for an explosion, it comprises that the emulsion explosive composition that makes each definition in the claim 1 to 11 blasts.