CN1164522A - Microemulsion and oil soluble gassing system - Google Patents
Microemulsion and oil soluble gassing system Download PDFInfo
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- CN1164522A CN1164522A CN96123311A CN96123311A CN1164522A CN 1164522 A CN1164522 A CN 1164522A CN 96123311 A CN96123311 A CN 96123311A CN 96123311 A CN96123311 A CN 96123311A CN 1164522 A CN1164522 A CN 1164522A
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
- C06B23/002—Sensitisers or density reducing agents, foam stabilisers, crystal habit modifiers
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
- C06B47/14—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase comprising a solid component and an aqueous phase
- C06B47/145—Water in oil emulsion type explosives in which a carbonaceous fuel forms the continuous phase
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Abstract
The present invention relates to a process for preparing an emulsion explosive which has been sensitized by the in-situ gassing of a chemical gassing agent, wherein the gassing agent is contained in a microemulsion. The invention also relates to the microemulsions utilized in the practise of this process. The use of the microemulsions of the present invention provides more complete mixing of the gas precursor with the constituents of the emulsion explosives. The process thus provides a more controllable reaction for the in-situ, chemical gassing of emulsions, and for the production of chemically gassed emulsion explosives at lower temperature.
Description
The present invention relates to an improved process for the preparation of an emulsion explosive and the incorporation of a dispersed gas phase in an emulsion explosive. The invention particularly relates to the sensitization of emulsion explosives by a chemical gassing process using a microemulsion system dispersed in the continuous oil phase of an emulsifier.
Emulsion explosive compositions are well known in the explosive industry. The emulsion explosive compositions currently in common use are first disclosed in U.S. Pat. No. 3,447,978(Bluhm) and contain the following components: (a) a discontinuous aqueous phase comprising discrete droplets of an aqueous inorganic salt solution that releases oxygen; (b) a continuous organic phase immiscible with water during dispersion of the droplets; (c) an emulsifier that forms an emulsion of droplets of an oxidizer salt solution in a continuous organic phase; and preferably (d) a discontinuous gas phase. In some emulsion explosive compositions, the discontinuous phase contains little or no water and such explosives are commonly referred to as low melting eutectic emulsions or melt-in-oil projectiles.
The emulsion composition is typically blended with a solid particulate oxidizer salt, which can be coated with an organic fuel in order to obtain an explosive that is superior in explosive performance and relatively inexpensive. This type of blend is commonly referred to as "antiknock emulsion". Compositions comprising a water-in-oil emulsion and Ammonium Nitrate (AN) particles or AN AN granule (ANFO) blend with a coating of fuel oil are described in Australian patent application 29408/71(Butterworth) and U.S. patent 3161551(Egly et al 4111717(Clay), 4181546(Clay) and 4357184(Binet et al). further, to provide a high density explosive composition, i.e., AN explosive composition having a density greater than ANFO, U.S. patent 4775431(Mullay) describes a water-in-oil microemulsion in combination with a solid particulate oxidizer salt, U.S. patent 4907368(Mullay&Sohara) describes a microemulsion in combination with a solid particulate oxidizer salt to form AN explosive composition having a density greater than ANFO, wherein the effect of the microemulsion system is to increase the density of the oxidizer salt.
The use of gas phase sensitized emulsion explosives and the use of AN or ANFO emulsion blends are well known in the art. In the preparation of these gas sensitised products it is important to achieve a uniform distribution of gas bubbles of the desired size.
Current methods for incorporating the gas phase in emulsion explosives include in situ gassing with chemical agents such as nitrites and incorporation of gas pockets, void materials such as microspheres or a mixture of gassing and microspheres or porous materials such as expanded materials such as perlite. Although microspheres provide a volume of voids and are uniformly distributed in the emulsion, they are relatively expensive to use compared to chemical aeration, and because of the difficulty of using microspheres in the field, they are only suitable for use on factory manufacturing equipment.
Mechanical mixing methods can also be used to produce a gas phase within lactic acid, but such methods generally do not provide an efficient distribution of the gas and therefore can result in poor gas phase stability due to bubble accumulation and leakage. Attempts have been made to overcome the above problems by using certain chemical agents to control the bubble size and stabilize the bubbles. Australian patent application 25706/88 and australian patent 578460(Curtin&Yates) disclose mechanical methods of incorporating gas bubbles in an emulsion using chemical reagents to provide a stable gas phase even in low viscosity emulsion explosives which are substantially free of paraffin.
In situ chemical aeration of emulsions is typically carried out by mixing chemical agents into the emulsion that decompose or react to form gas bubbles under the influence of the components in the emulsion. Suitable chemicals include peroxides such as hydrogen peroxide, nitrites such as sodium nitrite, nitrosamines such as N, N' -dinitrosopentamethylenetetramine, alkali metal borohydrides such as sodium borohydride and bases such as carbonates including sodium carbonate.
The most preferred chemical gassing agent for emulsions containing ammonium nitrate is sodium nitrite, which reacts with the discontinuous phase of the emulsion at acidic PH to produce nitrogen gas bubbles. The chemistry of the sodium nitrite decomposition is represented as follows:
It is important that the aeration reagent be mixed with the emulsion in such a way that there is sufficient opportunity for the aeration reagent to interact with the droplets of the oxidizer salt in the non-continuous phase, and a large number of sites must be provided for the micro-reaction between the aeration reagent and the oxidizer salt. The aeration reaction rate may be accelerated by chemical accelerators, which are known in the art for accelerating the decomposition of nitrite aeration agents; such accelerators may be incorporated into the discontinuous phase of the emulsion during manufacture or added to the aqueous nitrite solution to which the oxidizing agent or emulsion is added.
In order for the gassing reaction to occur uniformly, it is necessary for the gaseous medium reagent to be homogeneously distributed in the emulsion. Poor distribution of the flushing agent can affect the size and distribution of the bubbles formed in the emulsion explosive, which in turn can affect the efficiency of the reaction and even alter the reaction path.
The distribution of the aeration agent in the emulsion depends on several factors, including the nature of the carrier medium, the viscosity of the emulsion matrix, and the device used to disperse the aeration agent in the emulsion. Most unbuffered or "base" emulsions used in emulsion explosive compositions have a density of about 1.3 to 1.6g/cc, which is reduced to between 0.9 and 1.1g/cc by gassing. The gaseous chemical agents in the prior art are usually in the form of aqueous solutions or microemulsions. The amount of chemical gassing agent used to achieve the aforementioned density reduction is relatively small; there are inherent difficulties in achieving uniform distribution of small quantities of aeration agent compared to large quantities of emulsion. Regardless of the physical form of the dispersing device or carrier medium or aeration agent, current aeration techniques are limited in the degree of uniformity that can be achieved in dispersing the aeration agent in the base emulsion.
A further difficulty with current in situ gassing processes is that the gassing reaction is temperature sensitive and in order for the gassing reaction to occur at an acceptable reaction rate, the reaction temperature must be increased (typically above 40 ℃).
It has been found that improved aeration of base emulsions for emulsion explosive manufacture can be achieved by using an aeration agent in the form of a microemulsion which is capable of being dispersed in the base emulsion in a very fine physical form. The invention provides a gas reagent in an emulsion explosive, the reagent comprising a chemical gassing precursor, the precursor being present in a microemulsion comprising an aqueous solution of the gas precursor in an organic phase.
Preferably, the microemulsion aeration reagent is a water-in-oil microemulsion: an aqueous solution of a gas precursor; an organic phase and at least one emulsifier forming a microemulsion.
According to the invention, the micro-emulsion gassing agent in the base emulsion will cause the decomposition of the gas precursor or, more generally, a reaction, thereby forming gas bubbles in the base emulsion. Accordingly, the present invention provides a method of making a gassed emulsion explosive and provides a gassed emulsion explosive that is gassed using the microemulsion of the present invention.
The structure of microemulsions is very complex but is disclosed in us patent 4,907,368, as mentioned above, which is hereby incorporated by reference. However, microemulsion fluids are generally transparent, low viscosity and thermodynamically stable, which is contrary to the properties of normal or "giant" emulsions. Unlike macroemulsions, microemulsions form spontaneously-often referred to as pseudo-dissolution of a discontinuous phase in a continuous medium. Thus, when microemulsions are formed, the aqueous solution typically forms hydrated "domains" or small sized "droplets" in the oil phase.
The droplets of the aqueous or "discontinuous" phase of these microemulsions are many times smaller in volume than the droplets of comparable conventional emulsions. The droplet size of the microemulsion is generally in the range of about 1 to 100nm (10)-9m), more preferably from 1 to 50nm, most preferably from 30 to 50 nm. Due to the thermodynamic stability of microemulsion systems, microemulsions typically contain 1000 times more droplets than the same volume of conventional emulsions.
Microemulsion droplets are often referred to as "microreactors" since the reaction will occur within the very limited volume region provided by the droplet. Compared with the aeration reagent dispersing method in the prior art, the dispersion of the microemulsion aeration reagent in the base emulsion can provide more reaction centers, thereby increasing the efficiency of aeration reaction.
In a typical emulsion explosive system where the dispersed phase of the base emulsion contains AN and the gas precursor is sodium nitrite, the number of moles of sodium nitrite in each droplet of the micronized liquid gassing agent is much lower than the number of moles of AN in each droplet of the discontinuous phase of the base emulsion. This increases the effectiveness of the nitrogen generation and improves the bubble distribution in the emulsion explosive because the ratio of ammonium ions to nitrite ions is increased.
The amount of water-in-oil microemulsion gassing agent added to the base emulsion is preferably from 0.01 to 10% by weight, more preferably from 0.1 to 5% by weight, based on the total emulsion explosive.
The gassing reaction may be carried out at temperatures normally used in the gassing of emulsion explosives, but as a preferred feature the invention may be applied at lower temperatures than normally used. Thus in a preferred embodiment, the microemulsion may be base emulsion gassed at a temperature below 40 ℃, more preferably below 20 ℃ and most preferably below 10 ℃.
In a preferred embodiment, the water-in-oil microemulsion gassing agent consists of an optically isotropic fluid comprising gassing agent droplets with an average size of 30 to 50nm (0.03 to 0.05 μm).
The gas precursor of the present invention may be a chemical known in the art for in situ generation of gas bubbles. Particularly preferred gas precursors are selected from nitrous acid and its salts such as sodium nitrite. The amount of gas precursor in the microemulsion is preferably from 1 to 65% by weight, more preferably from 10 to 55% by weight, of the microemulsion gassing agent.
Whenever gaseous precursors of nitrite are used in an acidic environment in the presence of ammonium ions, different amounts of nitrogen oxide (NOx) are produced upon nitrite decomposition, however when used in microemulsion gassing systems, the amount of NOx is typically much less than the amount of NOx produced in typical prior art use nitrite gassing solutions. This reduction in the amount of NOx produced will preferably result in a generally produced NOx amount that is 5% lower, more preferably 70% lower, than the prior artnitrite flush solution.
The continuous oil phase of the microemulsion gassing agents of the present invention comprises one or more organic components, preferably selected from saturated or unsaturated hydrocarbons, cyclic or alicyclic hydrocarbons, aromatic hydrocarbons, glycerides and mineral oils or mixtures of two or more thereof.
The water used as the "aqueous" phase of the microemulsion gassing agent may be replaced in whole or in part by other solvents, provided that the other solvents are completely immiscible with the continuous phase forming the microemulsion and that the other solvents are sufficiently compatible with the entire emulsion explosive system. Nevertheless, the preferred fluid for the "aqueous" phase is to contain only water.
The emulsifier used to form the microemulsion gassing agent is selected from, for example, ionic and non-ionic surfactants (e.g., cetyltrimethylammonium salts, tetradecyl sulfates, dioctyl sulfosuccinate, fatty acid esters of sorbitol, and ethoxylated fatty acid sorbitan esters) and mixtures of two or more thereof. Depending on the formulation of the microemulsion, optionally a "co-surfactant" may be employed, said "co-surfactant" preferably being selected from normal linear or cyclic alcohols (such as isopropanol, butanol, pentanol, cyclohexanol or higher alcohols) and mixtures of two or more thereof.
In the microemulsified aeration agents of the present invention, the solubility of the discontinuous aqueous phase in the continuous oil phase depends on the nature of the surfactants and co-surfactants and the salinity of the aqueous phase. In a given oil/surfactant and co-surfactant system, the solubility of the aqueous phase generally decreases with increasing salt concentration.
In a preferred embodiment, the microemulsion gassing agents of the present invention comprise a surfactant and a co-surfactant system consisting of a mixture of cetyltrimethylammonium bromide (also known as cetyltrimethylammonium bromide or CTAB) and butanol or butanol, isopropanol or cyclohexanol or a mixture of two or more thereof. This system has been found to be very effective for dissolving sodium nitrite solution in light mineral oil such as diesel fuel.
Suitable microemulsion gassing agents for use in the present invention can be made by the following steps: (a) mixing (i) at least one microemulsion-forming surfactant and (ii) an organic phase, and (b) adding an aqueous solution of a gaseous precursor to the mixture of step (a) with stirring, thereby forming a microemulsion of said aqueous solution in said organic phase.
Further, the present invention also provides a method of forming an emulsion explosive composition, the method comprising the steps of: (a) forming a base emulsion by emulsifying an aqueous solution of an inorganic salt in a mixture of an organic phase and an emulsifier; and
(b) mixing a water-in-oil microemulsion aeration reagent into the base emulsion in the step (a).
The base emulsion to be incorporated into the microemulsion aeration reagent may be any water-in-oil or low-melting eutectic emulsion known in the art to be suitable for chemical aeration reagent sensitization.
For microemulsions containing sodium nitrite as a gas precursor, the base emulsion preferably contains ammonium ions, preferably from ammonium nitrate in the aqueous phase of the base emulsion.
The continuous organic phase of the base emulsion may comprise any organic fuel known in the art and include aliphatic cycloaliphatic or aromatic compounds or mixtures thereof. Suitable organic fuels may be selected from fuel oils, diesel, distillate, furnace oil, kerosene, naphtha, paraffin oil, benzene, toluene,xylene pitch material, polymer oils, animal oils, fish oils and other mineral, hydrocarbon or fatty oils, and mixtures of two or more thereof.
The continuous organic phase is generally present in an amount of from 2 to 15% by weight of the emulsion explosive composition, preferably from 3 to 10%.
Other optional fuel materials may be incorporated into the emulsion if desired, such fuels being hereinafter referred to as secondary fuels. Examples of secondary fuels include finely divided solids. Examples of solid sub-fuels include finely divided materials such as sulphur, aluminium, carbonaceous materials, resin acids such as abietic acid, sugars and other vegetable matter such as starch, nut flour, cereal flour and wood pulp and mixtures thereof.
The optional secondary fuel component of the emulsion is typically present in an amount of from 0 to 30% by weight of the emulsion explosive composition.
Suitable oxygen-releasing salts for use in the discontinuous aqueous phase of the emulsion-based ingredients of the emulsion explosive composition of the present invention are well known in the art and are preferably selected from the group consisting of alkali and alkaline earth metal nitrates such as calcium nitrate and perchlorate, ammonium nitrate, ammonium chlorate, ammonium perchlorate and mixtures thereof.
The oxygen-releasing salt content of the emulsion-based composition of the emulsion of the invention is generally from 45% to 95% by weight, preferably from 60 to 90% by weight, of the emulsion explosive composition.
The amount of water used in the emulsion explosive composition of the present invention is typically from 0 to 30% by weight of the emulsion explosive composition. When the emulsion explosive is a low-melting eutectic emulsion, the discontinuous phase will contain no water or only external water.
The base emulsion emulsifier component of the compositions of the present invention may be selected from a wide range of emulsifiers or emulsifier compositions known in the art suitable for use in the preparation of emulsion explosive compositions. Examples of such emulsifiers include alcohol alkoxylates, phenol alkoxylates, poly (oxyalkylene) glycols, poly (oxyalkylene) fatty acid esters, amine alkoxylates, fatty acid esters of sorbitol and glycerol, fatty acid salts, sorbitan esters, poly (oxyalkylene) sorbitan esters, fatty amine alkoxylates, poly (oxyalkylene glycol esters, fatty acid amides, fatty acid amide alkoxylates, fatty amines, quaternary amines, alkyloxazolines, alkenyloxazolines, imidazolines, alkylsulfonates, alkylaryl sulfonates, alkylsulfosuccinates, alkyl phosphates, alkenyl phosphates, phosphate esters, lecithins, poly (oxyalkylene) glycols and poly (12-hydroxystearic acid) copolymers, condensation products containing at least one primary amine compound and poly [ alk (en) yl]succinic acid or anhydride, and mixtures thereof&Baker), 29933/89 and 299832/89 describe condensates of at least one primary amine-containing compound with a poly [ alk (en) yl]succinic acid or anhydride.
The base emulsion emulsifier component of the compositions of the invention will generally comprise up to 5% by weight of the emulsion explosive composition.
In addition to the gas bubbles generated by the microemulsion gassing agents of the present invention, other voiding agents (hereinafter referred to as secondary voiding agents) may be used, for example, hollow glass or plastic microspheres, porous particulate materials, and mixtures thereof may be incorporated before or after the microemulsion gassing agents of the present invention are added to the base emulsion.
The content of the secondary voiding agent is preferably 0.05 to 50% by volume of the time-based emulsion without the microemulsion gassing agent; more preferably, the secondary voiding agent is present in an amount of from 0.05 to 40% by volume of the emulsion explosive composition after the microemulsion is added for gassing.
The base emulsion ingredients of the present invention may be formed by conventional methods well known in the art. Generally, the oxygen-releasing salt is dissolved in water at a temperature above the solution break point (fudge point), where the "break point" is the temperature at which the formation of crystals of the oxygen-releasing salt begins in the oxidizer solution, and the base emulsion is prepared by adding the aqueous composition to a rapidly stirred blend of the fuel phase and the base emulsion emulsifier. The base emulsion may further incorporate a particulated oxidizing salt such as prill A N or a coated oxidizing salt such as ANFO (ammonium nitrate-fuel oil). The ratio of base emulsion to granulated oxidizing agent salt is preferably between 10: 90 and 90: 10.
The invention will be further described with reference to the following non-limiting examples and figures 1 to 4, to which
FIGS. 1 to 4 show the density of the emulsion explosive as the gassing reaction proceeds versus time in the examples. All numerical values in the examples are by weight unless otherwise indicated.
Examples example 1
The microemulsion gasser of the present invention is prepared according to the following method. Cetyl trimethylammonium bromide (CTAB) (9 parts) was mixed with butanol (4.2 parts), and then diesel oil (35 parts) was added to form an oil phase. An aqueous solution containing sodium nitrite (30.5% by weight) was slowly added to the oil phase withgentle stirring. As the aqueous solution was added to the oil phase, the mixture slowly changed from milky to a clear pale yellow microemulsion, and the addition of the aqueous solution was continued until a microemulsion was formed containing 18 parts by weight of the aqueous solution of the salt (i.e., containing 18X 0.305 or 5.49 parts by weight of sodium nitrite, or 8.3% by weight of sodium nitrite). Example 2
CTAB (9 parts) was mixed with butanol (4.2 parts), and then diesel oil (35 parts) was added with stirring. An aqueous solution containing sodium nitrite (29.5% by weight) and sodium thiocyanate (5% by weight) was slowly added to the oil phase with stirring. As the aqueous solution was added to the oil and surfactant mixture, the mixture slowly changed from milky white to a clear pale yellow microemulsion, and the addition of the aqueous solution was continued until a microemulsion was formed containing 17.4 parts aqueous salt solution. Example 3
Water-in-oil based emulsions suitable for emulsion explosive compositions can be prepared by: a mixture of oil phase and base emulsion emulsifier is formed and then hot (90 ℃) oxidant salt solution, water and weak nitrous acid are added to the mixture under vigorous stirring. The composition and the pH of the resulting base emulsion are reported in Table 1. The resulting base emulsion was stored at 20 ℃ for 2 days and then mixed with an air-entraining agent (as described below). In the following experiments, the aeration rate was determined.
The base emulsion sample of example 3 was mixed with the following components;
3(i) -microemulsion of example 1 added in an amount of 1.15% by weight of the emulsion explosive.
3(ii) -addition to the microemulsion of example 2 in an amount of 1.24% by weight of the emulsion explosive.
3(iii) -adding to a conventional aeration solution consisting of an aqueous solution of sodium nitrite (11%) (by weight) and water (89%)) in an amount of 0.87% by weight of the emulsion explosive; and
3(iv) -adding to an amount of 0.4% by weight of the emulsion explosive a conventional gassing solution consisting of an aqueous solution of sodium nitrite (24%) and sodium thiocyanate (24%).
In each of examples 3(i) -3(iv), the amount of sodium nitrite added to the emulsion of example 3 was about equal.
TABLE 1
| Base emulsion Formula | Examples 3 | Examples 4 | Examples 5 | Examples 6 |
| pH | 2.0 | 3.2 | 3.2 | 3.9 |
| Ammonium nitrate | 73.90 | 73.55 | 73.55 | 73.55 |
| Water (W) | 11.46 | 18.32 | 18.32 | 18.43 |
| Acetic acid Dilute nitric acid | - 6.90 | 0.39 - | 0.39 - | 0.28 - |
| Thiourea | 0.14 | 0.14 | 0.14 | 0.14 |
| Diesel oil | 5.32 | - | 5.32 | 5.32 |
| Stone wax oil | - | 5.75 | - | - |
| Emulsifier* | 2.28 | 1.85 | 2.28 | 2.28 |
*: ethanolamine derivatives of polyisobutylene succinic anhydride.
The density versus time curve of the emulsion explosive in example 3 is shown in FIG. 1. The time measured at the completion of the gassing reaction indicates: the time taken for the base emulsion to mix with microemulsion gassing agent systems 3(i) and 3(ii) to reach an emulsion explosive density of 1g/cc is less than 10 minutes; whereas base emulsions mixed with conventional aeration solutions (iii) and (i) require 20 minutes or more. This indicates that at room temperature (20 c), the gassing reaction for a given emulsion explosive is accomplished faster with microemulsion systems than with conventional gasser systems. Example 4
A water-in-oil based emulsion suitable for use in forming an emulsion explosive was prepared according to the method described in example 3, except that dilute acetic acid was used in place of nitrous acid. The composition and pH of the resulting emulsion explosive are reported in table 1. Example 4(a)
The base emulsion was stored at 20 ℃ for 2 days and then mixed with an air-entraining agent to measure the effect of the air-entraining agent. The base emulsion sample of example 4 was mixed with the following components:
4(i) -addition to the microemulsion of example 1 in an amount of 1.0% by weight of the emulsion explosive (base emulsion previously treated with a 0.4% by weight sodium thiocyanate solution containing 24% potassium thiocyanate and 76% water); and
4(ii) -adding to an amount of0.4% by weight of the emulsion explosive a conventional gassing solution consisting of an aqueous solution of sodium nitrite (an aqueous solution of 24% sodium nitrite and 24% sodium thiocyanate).
For example 4(i), the nitrite added to the emulsion explosive composition was 0.083 wt% and for example 4(ii) 0.096 wt%.
The density versus time curve of the emulsion explosive is shown in FIG. 2 (a). The time measured at the completion of the gassing reaction indicates: the base emulsion mixed with the microemulsion gasser system (i.e. 4(i)) took an average time to complete the reaction of 10 minutes; in sharp contrast, the base emulsion mixed with the 4(ii) conventional aeration solution takes 40 minutes or more. Microemulsion systems are at least 4 times faster than conventional systems during all stages of the gassing reaction. This indicates that: despite the lower nitrite concentration, the rate of gassing of emulsion explosives prepared using microemulsion gassing agent 4(i) is much faster than the rate of gassing of emulsion explosives prepared using more conventional gassing solutions. Example 4(b)
The resulting base emulsion of example 4 was stored at 4 ℃ for 24 hours and then placed in a pre-cooled bowl and mixed with an air-entraining agent, and the effect was measured. The mixture was kept below 8 ℃ at all times.
The base emulsion sample of example 4(b) was mixed with the following components:
4(b) (i) -addition of the microemulsion of example 1 to an amount of 1.0% by weight of the emulsion explosive (base emulsion previously treated with a 0.4% by weight aqueous solution of sodium thiocyanate containing 24% of sodium thiocyanate and 76% of water); and
4(b) (ii) -adding to an amount of 0.4% by weight of the emulsion explosive a conventional gassing solution consisting of an aqueous solution of sodium nitrite (an aqueous solution of 24% sodium nitrite and 24% sodium thiocyanate).
The nitrite added to the emulsion explosive composition in example 4(b) (i) was 0.083 wt% and in example 4(b) (ii) was 0.096 wt%. The only substantial difference between the tests performed in examples 4(a) and 4(b) is the temperature of the inflation.
The density versus time curve of example 4(b) is shown in FIG. 2 (b). The time measured at the completion of the gassing reaction indicates: the average time taken for the emulsion explosive produced from microemulsion gassing agent system 4(b) (i) to reach a density below 1.1g/cc was 15 minutes; whereas emulsion explosives prepared using the conventional gassing solution of 4(b) (ii) take 60 minutes or more. Microemulsion systems are at least 4 times faster than conventional systems at all stages of the gassing reaction. This indicates that: despite the lower nitrite concentration, the gassing rate of emulsion explosives prepared using microemulsion gassing tests is much faster than that of emulsion explosives prepared using conventional gassing solutions. From a comparison of example 4(a) and example 4(b) it can be seen that: the micro-emulsion air-flushing agent has better performance than the conventional air-flushing agent even if air-flushing is carried out at low temperature. The microemulsion aerating agent is also superior to the conventional aerating agent. Example 5
A water-in-oil based emulsion suitable for use in an emulsion explosive composition was produced according to the method described in example 4. The composition and pH of the resulting base emulsion are reported in table 1. The resulting base emulsion was stored at 4 ℃ for 24 hours, then placed in a bowl, mixed with an air-entraining agent, and the effect thereof was measured. The mixture was kept below 8 ℃ at all times. The base emulsion of example 5 was mixed with the following components.
5(i) -addition to the microemulsion of example 1 in an amount of 1.0% by weight of the emulsion explosive (the base emulsion was previously treated with a 0.4% by weight aqueous solution of sodium thiocyanate containing 24% of sodium nitrite and 76% of water);
5(ii) -addition to the microemulsion of example 1 in an amount of 0.83% by weight of the emulsion explosive (base emulsion previously treated with a 0.4% by weight aqueous solution of sodium thiocyanate containing 24% of sodium nitrite and 76% of water);
5(iii) -addition to the microemulsion of example 1 in an amount of 0.5% by weight of the emulsion explosive (the base emulsion was previously treated with a 0.4% by weight aqueous solution of sodium thiocyanate containing 24% of sodium nitrite and 76% of water); and
5(iv) -adding to an amount of 0.4% by weight of the emulsion explosive a conventional gassing solution consisting of an aqueous solution of sodium nitrite (an aqueous solution of 24% sodium nitrite and 24% sodium thiocyanate).
The nitrite added to the emulsion explosive in example 5(i) was 0.083 wt%, example 5(ii) was 0.069 wt%, example 5(iii) was 0.041 wt% and example 5(iv) was 0.096 wt%.
The density versus time curve is shown in fig. 3. Measurement of the time for completion of the gassing reaction indicated: the average time taken for the emulsion explosives prepared from microemulsion gassing agent systems (i.e., the emulsion explosives prepared in examples 5(i), 5(ii), and 5(iii) to reach a density of the like or less than 1.2g/cc is 5 to 7 minutes; while the emulsion explosives prepared using the conventional gassing solution of example 5(iv) take 30 minutes or more
A water-in-oil base emulsion suitable for use in an emulsion explosive composition was prepared according to the following method: the oil phase and emulsifier mixture is formed and then slowly added to a hot solution of the oxidant salt, water and dilute acetic acid with vigorous stirring. The composition and the pH of the base emulsion thus formed are reported in Table 1. The resulting base emulsion was stored at room temperature for 2 days and then mixed with an air-entraining agent to measure the effect of the air-entraining agent.
The base emulsion of example 6 was mixed with the following components:
6(i) -microemulsion of example 1 added to an amount of 1.17% by weight of the emulsion explosive;
6(ii) -adding the microemulsion of example 2 in an amount of 1.24% by weight of the emulsion explosive;
6(iii) -adding to a conventional gassing solution consisting of an aqueous solution of sodium nitrite (24% sodium nitrite and 76% water) in an amount of 0.4% by weight of the emulsion explosive; and
6(iv) -conventional gassing solution consisting of aqueous sodium nitrite (24% sodium nitrite and 24% sodium thiocyanate) was added in an amount of 0.4% by weight of the emulsion explosive.
Almost equal amounts of sodium nitrite were incorporated into each of the prepared emulsion explosives in the form of microemulsions (examples 6(i) and 6(ii)) or aqueous solutions of sodium nitrite (examples 6(iii) and 6 (iv)).
The density versus time curve of the emulsion explosive is recorded in fig. 4. The time of completion of the gas reaction in the measurement indicated that: the emulsion explosives produced by the microemulsion gasser system (examples 6(i) and 6(ii) exhibited faster gassing rates than emulsion explosives produced by conventional gassers (examples 6(iii) and 6(iv), even in the absence of a gassing promoter (sodium thiocyanate), and moreover a gassing promoter was also used in example 6 (iv).
It is clear that the microemulsion system follows the first order kinetics (first order kinetics) of the main generation of nitrogen, and table 2 records the rate constants for determining the microemulsion and conventional gassing systems. The results show that: the aeration rate of the microemulsion system is always greater than that of the conventional aeration solution regardless of the conditions of temperature and pH value; it has also been shown that: when the pH is lowered from 3.9 to 3.2, the aeration rate of the microemulsion system increases by about 5 times, whereas the conventional system increases only by 1.5 times. Table 2: constant of reaction rate
Example 7
| pH3.2 The temperature is 4 DEG C | pH3.2 The temperature is 20 DEG C | pH3.9 The temperature is 20 DEG C | |
| Conventional inflation Solutions of | 5.0×10-4S-1 | 1.2×10-3S-1 | 8.0×10-4S-1 |
| Microemulsion punch Gas system | 2.0×10-3S-1 | 5.5×10-3S-1 | 1.2×10-3S-1 |
To compare the amount of NOx generated during the gassing reaction, further experiments were conducted using the base emulsion composition of example 6. All tested emulsions contained an aqueous phase at ph 3.9. The NOx production amount upon decomposition of nitrate ions was measured.
The base emulsion was warmed to 30 ℃ and then mixed with the following ingredients:
7(i) -addition of the microemulsion of example 1 in an amount of 1.15% by weight of the emulsion explosive; and
7(ii) -adding to an amount of 0.4% by weight of the emulsion explosive a conventional gassing solution consisting of an aqueous solution of sodium nitrite (an aqueous solution of 24% sodium nitrite and 24% sodium thiocyanate).
The amount of chemical insufflation added to each composition should be sufficient to provide an emulsion having a final density of about 0.70 g/cc. After mixing with the gassing agent, the emulsion explosive is held in a sealed container provided with a transfer pipe. After the gas charging reaction is finished, the container is balanced to room temperature, gas generated in the container is discharged through a pipeline, and the NOx sample is analyzed. The results are shown in Table 3.
TABLE 3
| NOx amount per kg emulsion | |
| Conventional aeration solution | 4.7ppm |
| Microemulsion gas flushing system | 1.6ppm |
Table 3 shows that the microemulsion gassing system produced lower amounts of NOx compared to the conventional gassing system. This is further confirmed by: the use of the microemulsion gassing agent instead of the conventional gas solution improves the efficiency of the gassing reaction. Example 8
A microemulsion with a higher sodium nitrite concentration is prepared. 55 parts by weight of a 28% by weight aqueous sodium nitrite solution were mixed with 45 parts of an oil phase mixture containing 2 parts by weight of isopropanol, 2.2 parts of butanol, 35 parts of fuel oil and 9 parts of CTAB. The mixture forms a stable microemulsion suitable for use in the gassing of emulsion explosives. While the specification describes particular embodiments of the invention, it will be appreciated that modifications may be suggested to those skilled in the art, and it is intended to cover all such modifications as fall within the scope of the appended claims.
Claims (25)
1. An emulsion explosive gasser comprising a chemical gasser precursor, said gasser precursor being present in a microemulsion comprising an aqueous solution of the gas precursor in an organic phase.
2. A microemulsion insufflation agent in accordance with claim 1 suitable for use in an insufflation based emulsion for the preparation of an emulsion explosive, said microemulsion insufflation comprising a water-in-oil microemulsion:
an aqueous solution of a gas precursor;
an organic phase; and
at least one microemulsion-forming emulsifier.
3. A water-in-oil microemulsion aerater according to claim 2, which aerater is an optically isotropic fluid comprising "droplets" of an aqueous solution, said droplets having an average size of 1 to 100 nm.
4. A water-in-oil microemulsion aerater according to claim 3, wherein said aqueous phase droplets have an average size in the range of 30 to 50 nm.
5. The water-in-oil microemulsion gasser according to any of claims 1 to 4, wherein the gas precursor is selected from nitrous acid and its salts and mixtures thereof.
6. A water-in-oil microemulsion gassing agent according to claim 5 wherein the gas precursor is sodium nitrite.
7. The water-in-oil microemulsion aerater according to claim 1 or 2, wherein the microemulsion aerater contains 1 to 65% by weight of gas precursors.
8. A water-in-oil microemulsion aerater according to claim 7, wherein the microemulsion aerater contains 10 to 55% by weight of gasprecursor.
9. The water-in-oil microemulsion aerating agent according to claim 1 or 2, wherein the oil phase comprises saturated or unsaturated hydrocarbons, cyclic or alicyclic hydrocarbons, aromatic hydrocarbons, glycerol esters, mineral oils or mixtures of two or more thereof.
10. A water-in-oil microemulsion aerating agent according to claim 2, wherein the emulsifier is an ionic or nonionic surfactant or a mixture of two or more thereof.
11. A water-in-oil microemulsion aerating agent according to claim 10, wherein the surfactant is cetyltrimethylammonium salt, tetradecyl sulfate, dioctyl sulfosuccinate, sorbitan fatty acid ester or ethoxylated sorbitan fatty acid ester or a mixture of two or more thereof.
12. A water-in-oil microemulsion aerater according to claim 10, further comprising a co-surfactant.
13. A water-in-oil microemulsion aerater according to claim 12, wherein said co-surfactant is a linear or cyclic alcohol or a mixture of two or more thereof.
14. A water-in-oil microemulsion aerators according to claim 12 comprising surfactants and a co-surfactant system consisting of a mixture of cetyltrimethylammonium bromide and butanol, isopropanol or cyclohexanol or a mixture of two or more thereof.
15. A method of producing an aeration agent suitable for use in aerating an emulsion explosive, the method comprising:
(a) mixing (i) at least one microemulsion-forming surfactant and (ii) anorganic phase, and
(b) adding a gaseous precursor to the mixture of step (a) with stirring,
thereby forming a microemulsion of the aqueous solution in the organic phase.
16. A method of producing an emulsion explosive composition, the method comprising the steps of:
(a) forming a base emulsion by emulsifying an aqueous inorganic salt solution in a mixture of an organic phase and an emulsifier; and
(b) mixing the water-in-oil microemulsion aerating agent into the base emulsion in the step (a).
17. A process for the manufacture of an emulsion explosive composition according to claim 16 wherein the amount of water-in-oil microemulsion gassing agent added to the emulsion explosive is from 0.01 to 10% by weight of the emulsion explosive.
18. A process for the manufacture of an emulsion explosive composition according to claim 17 wherein the amount of water-in-oil microemulsion propellant added to the emulsion explosive is from 0.1 to 5% by weight of the emulsion explosive.
19. The process for producing an emulsion explosive composition according to claim 16 further comprising mixing said emulsion explosive with a particulated oxidizer salt.
20. A process for the manufacture of an emulsion explosive composition according to claim 16 wherein the microemulsion gasser is mixed with the base emulsion of step (a) at a temperature of less than 40 ℃.
21. A process for the manufacture of an emulsion explosive composition according to claim 20 wherein said temperature is less than 20 ℃.
22. A process for the manufacture of an emulsion explosive composition according to claim 20 wherein said temperature is less than 10 ℃.
23. An emulsion explosive composition produced by the method of any one of claims 16 to 22.
24. The emulsion explosive composition according to claim 23, which produces less than 50% of the amount of NOx produced by an emulsion explosive used for comparison obtained by using an aqueous solution of a propellant in place of a microemulsion propellant in the preparation of a microemulsion.
25. The emulsion explosive composition according to claim 23, which produces less than 70% of the amount of NOx produced by an emulsion explosive used for comparison obtained by using an aqueous solution of a gassing agent in place of the gassing agent of the microemulsion when preparing the microemulsion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002163682A CA2163682A1 (en) | 1995-11-24 | 1995-11-24 | Microemulsion and oil soluble gassing system |
| CA2163682 | 1995-11-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1164522A true CN1164522A (en) | 1997-11-12 |
Family
ID=4157023
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN96123311A Pending CN1164522A (en) | 1995-11-24 | 1996-11-23 | Microemulsion and oil soluble gassing system |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0775681A1 (en) |
| CN (1) | CN1164522A (en) |
| AU (1) | AU7194296A (en) |
| CA (1) | CA2163682A1 (en) |
| ZA (1) | ZA969483B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113024334A (en) * | 2021-03-24 | 2021-06-25 | 葛洲坝易普力湖北昌泰民爆有限公司 | Oil phase for preparing medium-low temperature sensitization process emulsion explosive by using coal-to-liquid intermediate product and preparation method thereof |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5670739A (en) * | 1996-02-22 | 1997-09-23 | Nelson Brothers, Inc. | Two phase emulsion useful in explosive compositions |
| US8114231B2 (en) | 2005-10-26 | 2012-02-14 | Newcastle Innovation Limited | Gassing of emulsion explosives with nitric oxide |
| PE20080896A1 (en) * | 2006-08-29 | 2008-08-21 | African Explosives Ltd | EXPLOSIVE SYSTEM THAT HAS A BASIC EMULSION AND A SENSITIZING SOLUTION |
| CA2675167A1 (en) * | 2007-01-10 | 2008-07-17 | Newcastle Innovation Limited | Methods for gassing explosives especially at low temperatures |
| EP2396288B1 (en) * | 2009-11-12 | 2013-12-11 | Ael Mining Services Limited | Use of a sensitizing composition for an explosive |
| WO2012159127A2 (en) * | 2011-05-17 | 2012-11-22 | Ael Mining Services Limited | Emulsion explosive sensitising |
| US11565981B2 (en) | 2018-12-11 | 2023-01-31 | STT-Surfex Technology & Trading Pty Ltd | Water-based explosive |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3161551A (en) | 1961-04-07 | 1964-12-15 | Commercial Solvents Corp | Ammonium nitrate-containing emulsion sensitizers for blasting agents |
| US3447978A (en) | 1967-08-03 | 1969-06-03 | Atlas Chem Ind | Ammonium nitrate emulsion blasting agent and method of preparing same |
| US4111717A (en) | 1977-06-29 | 1978-09-05 | Leeds & Northrup Company | Small-size high-performance radiation thermopile |
| US4181546A (en) | 1977-09-19 | 1980-01-01 | Clay Robert B | Water resistant blasting agent and method of use |
| NZ192888A (en) | 1979-04-02 | 1982-03-30 | Canadian Ind | Water-in-oil microemulsion explosive compositions |
| AU2607688A (en) * | 1987-09-30 | 1989-04-18 | Mining Services International Corporation | Methods and compositions related to emulsified gassing agents for sensitizing explosive compositions |
| US4775431A (en) | 1987-11-23 | 1988-10-04 | Atlas Powder Company | Macroemulsion for preparing high density explosive compositions |
| US4907368A (en) | 1987-11-23 | 1990-03-13 | Atlas Powder Company | Stable fluid systems for preparing high density explosive compositions |
| US4830687A (en) * | 1987-11-23 | 1989-05-16 | Atlas Powder Company | Stable fluid systems for preparing high density explosive compositions |
| CN1023213C (en) * | 1989-03-04 | 1993-12-22 | 甘肃省化工研究院 | Emulsion explosive and its production process |
| US4960475A (en) * | 1990-03-20 | 1990-10-02 | Cranney Don H | Surfactant for gassed emulsion explosive |
-
1995
- 1995-11-24 CA CA002163682A patent/CA2163682A1/en not_active Abandoned
-
1996
- 1996-11-12 ZA ZA969483A patent/ZA969483B/en unknown
- 1996-11-14 EP EP96308223A patent/EP0775681A1/en not_active Withdrawn
- 1996-11-22 AU AU71942/96A patent/AU7194296A/en not_active Abandoned
- 1996-11-23 CN CN96123311A patent/CN1164522A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113024334A (en) * | 2021-03-24 | 2021-06-25 | 葛洲坝易普力湖北昌泰民爆有限公司 | Oil phase for preparing medium-low temperature sensitization process emulsion explosive by using coal-to-liquid intermediate product and preparation method thereof |
| CN113024334B (en) * | 2021-03-24 | 2022-04-22 | 葛洲坝易普力湖北昌泰民爆有限公司 | Oil phase for preparing medium-low temperature sensitization process emulsion explosive by using coal-to-liquid intermediate product and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2163682A1 (en) | 1997-05-25 |
| AU7194296A (en) | 1997-05-29 |
| ZA969483B (en) | 1997-06-02 |
| EP0775681A1 (en) | 1997-05-28 |
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