CA1203690A - Emulsion blasting agent with amine-based emulsifier - Google Patents

Abstract

ABSTRACT OF DISCLOSURE

An explosive oil-in-water emulsion and a method of manufacture is disclosed. The process comprises combining a liquid carbonaceous fuel and an aqueous solution of at least one inorganic oxidizing salt, with agitation, in the presence of ingredients A and B, ingredient A being selected from the group consisting of oleic acid, linoleic acid and mixtures thereof, and ingredient B being selected from the group consisting of C1 - C6 alkylamines, C1 - C6 alkyldi-amines, hydrazine, C2 - C6 alkanolamines, urea and mixtures thereof, incorporating dispersed gas bubbles into the resulting water-in-oil emulsion, one of said ingredients A
and B being added before or during agitation and the remaining ingredient of ingredients A or B being added during agitation.

Description

Emulsion Blasting Agent With Amine-Based Emulsifier The present invention relates to water-in-oil emulsion type explosive compositions which contain an aque--ous solution of inorganic oxidizing salt as a dispersedphase within a continuous carbonaceous fuel phase.
Water-in-oll emulsion type explosive compositions are known.
H.F. Bluhm, in U.S. Patent 3 447 987 which issued L0 1969 June 3, disclose~ water-in-oil emulsion blas~ing agents. The blasting agents have an aqueous solution compo-nent forming a discontinuous emulsion phase, a carbonaceous ~uel component forming a con-tinuous emulsion phase and an occluded gas component dispersed within ~he emulsion and forming a discontinuous emulsion phase. A water-in-oil type emulsifying agent is used to form the emulsion. A large number of emulsifyirlg agent~s are indicated as being suitable e.g. sorbi-tan fatty acid esters, polyoxyethylene sorbital esters and isopropyl ester of lanolin fa-tty acids. The emulsion blasting agent of Bluhm is made by mixing the a~ueous solution and the carbonaceous fuel components wi-th the emulsifying agent. The gas may be occluded during such mixing, or in a separate step after formation of the emulsion. The emulsifying agents disclosed are well known ~5 -Eor form:ing water-in-oil emulsions.
E.A. Tomic, in U.S. Patent 3 770 522 which issued l973 November 6, disclos2s a water-in-oil emulsion blasting agent which contains an ammonium or alkali metal stearate salt emulsifying agent. According to Tomic, a surprising feature of the blasting agent, in view of the fact that the value of the hydrophilic-lipophilic balance (HLB) of stearate salts is abou-t 1~, is that the s-tearate emulsifying agent forms a water-in-oil emulsion. In general, emulsifying agents having ~L~ values of 11-20, and particularly those having H~ values closer to 20 tend to Eorm oil-in water emulsions rather than water-in-oil etnulsions.
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~he emulsion blasting agent of Tomic is made by mixing an aqueous solution o an oxidizing salt, a carbonaceous fuel component and the emulsifying agent.
The hydrophilic-lipophilic balance sys-tem is the subject o:E numerous publications, for example "Classifica-tion of surface active agents by HLs"~ W.C. Griffen, J. Soc.
Cosmetics Chemists 1311 (1949), "Calculation of HLB values of non-ionic surfactants" ibid 5249 (1954~; "The Atlas HLB
system" Atlas Chemical Industries, Inc., Wilmington, Delaware, 4th printing, May 1971; and Proceedings Second Int. Congr. Sur. Act. 1426 (1957) Academic Press, New York, NY. HLB values reflect the hydrophilic content of the mole-cule of the compound under consideration.
W.B. 5udweeks and H.A. Jessop, in U.S. Patent 4 141 767 which issued 1979 February 27, disclose an emul-sion blasting composition having, as an emulsifier, from about 0.5 to 5~ by weight of the total composition, of a fatty acid amine or ammonium salt having a chain length Erom 14 to 22 carbon atoms. The method of preparing the emulsion comprises predissolving the emulsifier in a liquid hydro-carbon fuel and then adding the emulsifier/fuel mixture to a solution of oxidizing salts. Other ingredients may be added. Examples of suitable emulsifiers disclosed are ~rmac* HT saturated C16 - Clg al]cylammonium acetate, Armac C
C16 - Clg alkyl-ammonium acetate and Armac T unsaturated C16 - Clg alkyl-ammonium acetate.
J.H. Owen II, in U.S. Patent 4 287 010 which is-sued 1981 5eptember 1, discloses an emulsion blas-ting agent comprising a carbonaceous fuel forming a continuous emulsion phase, an aqueous solution o an inorganic oxidizing salt forming a discontinuous emulsion phase dispersed in the continuous phase, dispersed gas bubbles and an ammonium or alkali metal salt o:E a fatty acid. The fatty acid salt is formed in situ Erom the .fatty acid and the ammonium or alkali metal hydroxide at the time when the aqueous solution * denotes trade mark.

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and carbonaceous Euel are brought -together, or just before or after they are brought together. J.~I. Owen I I indicates that organic derivatives of ammonium hydroxide e.g.
tetramethylammonium hyaroxide may be used in lieu o~
ammonium hydroxide.
The emulsion blasting agents of Owen are believed to have better water resistance than those of, for example, Bluhm. However the ingredien~s used in the manufacture of the emulsifying agent used for making the blasting agents of Owen tend to be difficult to handle e.g. are corrosive and also tend to be expensive. Ingredients which overcome these disadvantages and which provide emulsion blasting agents which tend to be stable at low temperatures have now been Eound.
Accordingly the present invention provides a method .Eor producing a wat~r-in oil emulsion-type explosive composition comprising cornbining a liquid carbonaceous fuel and an aqueous solution of at least one inorganic oxidizing salt, w.ith agitation, in the presence o:E ingredients A and ~, ingredient A being selected from the group consisting of oleic acid, linoleic acid and mixtures thereo~, and ingre-dient B being selected from the group consisting of Cl - C6 alkylamines, Cl - C6 alkyldiamines, hydrazine, C2 - C6 alkanolamines, urea and mixtures thereof, incorporating ~5 dispersed gas bubbles into the resulting water-in- oil emuls.ion, one o:E said i.ngredients A and B being added before or cluring agitation and the remainlng ingredient of ingredients A or B being added during agitation.
A preferred process comprises:
a) aclding a carbonaceous fuel, which is liquid at a temperature oE at least 65C, or an aqueous solution of at least one inorganic oxidizing salt, to a blender;
b) agitating said aqueous solution or carbona-ceous fuel;

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c) adding an emulsifier precursor ingredient to the aqueous solution or carbonaceous fuel, said precursor ingredient being selected from ingredients A and B, said ingredient A being selected from the group consisting of oleic acid, linoleic acid and mixture~ thereof, said ingredient B being selected from the group consisting of Cl - C6 alkylamines, Cl - C6 alkyldiamines, hydrazine, C2 - C6 alkanol-amines, urea, and mixtures thereof;
d~ adding the carbonaceous fuel or aqueous solution whichever was not added durlng step a);
e) adding ingredient A or ingredient B, whichever was not added during step c);
f) increasing the rate of agitation of the mix-ture of ingredients added during steps a), c), d), and e) to form a water-in-oil emulsion.
In a preferred embodiment further ingredients may be added during any of steps a~ to f), said further ingre-dients being selected from :Euels, explosivest gas entraining agents and solid inorganic o~idizing salts.
~ le presen-t invention also provides an explosive water-in~-oil emulsion comprising from 5 to 22 parts by weight water, from 60 to 80 parts by weight of at leas-t one oxidi~ing salt, from 2 to 10 parts by weight of a liquid carbonaceolls fuel, and an emulsifier made from ingredients A
and B, ingredient A being selected Erom the group consisting of oleic acid, linoleic acid and mix-tures thereof, ingre-dient B being selected from the group consis-ting of Cl ~ C6 alkylamines, Cl - C6 alkyldiamines, hydrazine, C2 - C6 alkanoalamines, urea and mixtures thereof, said emulsion having a density between 1.00 and 1~35 g/cm3.
Examples of solid inorganic oxidizing salts include grained or prilled ammonium nitra-te (AN), sodium 6~

nitrate ~SN) and calcium nitrate. Examples of Euels include liquid carbonaceous fuels e.g. formamide, fuel oil or ethylene glycol, solid carbonaceous fuels e.gO coal, gilsonite or sugar, and non-carbonaceous fuels e.g. sulphur or aluminium. Examples of explosives are prilled or flaked trinitrotoluene (TNT3, monomethylamine nitrate (MMAN), pentaerythr:itoltetranitrate (PETN~ and Composition ~.
Examples of gas entraining agents are those agents which encapsulate the gas e.g. glass microballoons and agents l~ which carry the gas in close association therewith e.g.
expanded perlite, flake aluminium.
The amoun-t of oxidizing salt employed in the pre-sent invention is generally between about 60 to 80 weight percent of the emulsion, and is preferably between about 70 and 78 weight percent. Preferably at least three quarters of the oxidizin~ salt is dissolved in aqueous solution.
More preferably all of the oxidizing salt is dissolved in aqueous solution. Water is generally present be~ween about 5 and 25 weight percent of the emulsion, preferably between 12 and 18 weight per~ent~
The liquid carbonaceous fuel ~hich forms the con-timlous phase oE the e~ulsion is generally present in a~nounts b~tween about 2 and about 10 weight percent, preEer-ably l~etween about 3 and about 6 weigh-t percent, of the ~S emul.sion. The amount selected may depencl on the presence of other euels in the emulsion and whether such other fuels are soluble or insoluble in the continuous phase. Examples of the liquid carbonaceous fuel are aliphatic, alicyclic and aromatic liquid hydrocarbons e.g. xylenes, kerosene, ~uel oils, paraffin oils and other organic carbonaceous fuels.
Other examples are Rando* HD-22 mineral oil, corvus oil and #2 diesel fuel.
Additional ingredients e.g. fuels, explosives and gas entraining agents may be added, in an amount generally up to abou~ 12 weight percent of the emulsion.
If solid inorganic oxidi~ing sal~ e.g. gralned or pr.lled ~N, is added, it may be added alone or in * denotes trade mark.

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combination with a fuel e.g. as ammonium nitrate/~2 diesel :Euel (~NFO) or ammonium nitrate/nitropropane.
The density and sensitivity o~ the emulsion is af~ected by the presence or absence of dispersed gas bubbles in the emulsion. Such gas bubbles may be dispersed in the emulsion through incorporation of air occluded in the emul-sion merely as a consequence o:E the agi~ation o the ingre-dients during mixing. The gas may be injec-ted or otherwise deliberately introduced by sparging or by adding chemical agents e.g. N, N'dinitrosopentamethylenetetramine. Alter-natively the gas bubbles may be encapsulated in glass or other known materials e.g. 1y ash 10aters. Encapsulated gas, sometimes referred to herein as microballoons, is advantageous where it is desired to detonate the emulsion under high hydrostatic pressures or in boreholes separated by low scaled distances e.g. between about 0.6 and 1Ø
Generally, only about 0.5 to 2 weight percent of the micro-balloons in the emulsion are required. The required dimen~
sions of the gas bubbles for obtaining pressure resistance and Eor sensitivity are wéll ~nown in the art.
The emulsions made using the present process may be made by first dissolving most or all of the inorganic ox.idi.zing salt or salts in water and heating the resulting aqueous solution to a tempera~ure oE between about 65 and ~'~ about l50C. The solution ma~y be added to a blender e.g. a ribbon blender or turhine blender, prior to adding one o~
the emulsiEier precursor ingredients. It is preEerred to add the emulsi~ier precursor ingredient to the aqueous solution while agitating the solution, in order to disperse the precursor ingredient~
Although it is not necessary to do so the fatty acid precursor ingredient e.g. oleic acid is usually added to the aqueous solution. It is pre~erable that the temperature o~ the solution at this stage be between about 40 and 75C. At the lower end o~ the tempera-ture range, an emulsion will Eorm when the temperature o~ the mixture is at 6~

or above the solubility point of the salts in solution.
Addi-tion of certain salts e.g. monomethylamine nitrate~ de-presses the temperature at which the emulsion may form. At the upper end of ~he temperature range, less agitation is required in -the subsequent step in order to :Eorm an emul-sion. However, a~ temperatures above about 75C it may be very difficult or impossible to Eorm an emulsion. The most preEerred temperature range of the solution at this stage is Erom about 50 to 70C.
The carbonaceous ~uel e.g. fuel oil, is then add-ed, while continuing agitation in the blender. Subsequently the second emulsifier precursor ingredient is added. The rate of agitation necessary to ~orm the emulsion is easily determined through routine experimentation. The rate of agitation required to form the emulsion is higher than that re~uired to merely blend the ingredients. To exemplify, a 5 cm diameter laboratory mixer may require at least about 1200 revolutions per minute of the mixer blades, while a 30 cm diameter laboratory mixer may only require at least about 240 revolutions per minute o~ its mixer blades. As the emulsion forms, the emulsion becomes thicker and the power requirement Eor the blender increases sharply. The emulsion forms more easily at higher temperatures, less agitation being required than at lower ternperatures. Ingredient B of ~5 the emulsifier may he added in solid i.e. powdered, form.
It is not necessary that the solid be dissolved prior to additi.on.
Other liquid ingredients e.g. ethylene glycol, may be added at any time prior to formation of the emulsion.
Other solid ingredients may be added at any time prior to the time where the sharp increase in power requirement occurs but it is preferable that such solid ingredients be added before addition of -the irst emulsifier precursor ingredient.
Commercially available oleic or l:inoleic acids tend -to be mixtures of fatty acids. Such mixtures are 3~

also use-Eul ln the present invention and fall within the scope of the terms "oleic acid" and "linoleic acid"~
The present proce~s may be practised in relatively small blenders e.g. holding up to about 1000 kg, intended or preparing a suE~icient quantity of emulsion ~or packaging into 25 - 150 mm diameter packages. The process may also be practised in large blenders e.g. holding up to about 2300 kg or more, in prsparation or pumping t~e emulsion directly into boreholes.
It has been Eound that the temperature oE the emulsion, when in the borehole, has little e~Eect on sensi-tivity, to detonation, o the explosive. Temperature of the emulsion does have a marked efect on emulsion stability, however. At low ~emperatures e.g. below about 4C, crystallization of the salts in the emulsion may lead to emulsion breakdown. Presence, in -the emulsion, of monomethylamine nitrate or other salts, tends to depress the lowest temperature at which emulsion breakdown becomes apparent. Presence of monomethylamine nitrate may depress this temperature to about -18C. At high temperatures, e.g.
above 40C, evaporation may also cause instability.
Particularly preferred of ingredients B are the alkylamines and alkanolamines because the emulsions Eormed therewith tend to have better stability at ;ow temperatures e.g. there is less of a tendency Eor the salts in the emul-sion to crystallize at low temperatures. Of particular interest because of its cost and availability is e-thanol-amine. Other useEul ingredients ~ include, but are not limited to, monomethylamine, ethylamine, dimethylamine, and guanidine. If ingreclient B is gaseous at ambient tempera-ture, e.g. monomethylamine, then it should Eirst be dissolv-ed in water prîor to adding to the mixture.
The present invention is illustrated by reference to the ollowing Examples.
E mple 1 4.21 kg o:E an ~0 wt % ammonium nitrate solution ; ~ ZI)36~

were added, at 88C, to a ribbon blender of 45.4 kg nominal capacity. 454 g of Q-Cell* 300 microb~lloons were added to the solution and -the ribbon blades were rotated at 50 rpm for about one minute. A blend of 1589 g Rando HD-22 mineral oil and 795 g of oleic acid was added to the blender, and agitation of the ribhon blades at 50 rpm was continued for one minute. 454 g of ethanolamine were added to the blender and after 60 seconds the rotation of the ribbon blade was increased to 250 rpm for about 10 minutes. An emulsion was formed, the final temperature being about 59C and the density, at 20C, being 1.26 g/cm3. The viscosity of -the emulsion, after cooling to 50OC! was 250 Pa. 5. Over a period of 20 days at 20C, the viscosity increased to 355 Pa.s. Viscosity was measured using a Brookfield* VFN
viscometer.
The emulsion explosive detonated at 6098 m/s, un-confined at 4C, in 150 mm diameter when primed with a No.
12 blasting cap plus a 450 g TNT primer.
Example 2 Example 1 was repeated except that 908 g of ex-panded fly ash was used instead of Q-Cell 300 microballons.
The initial viscosity was 255 Pa.s, measured at 55C. The velocitv of de~onation was 5671 m.s~l at 4C, in 150 mm di-ameter steel pipe, when primed with a No. 12 blasting cap plus a 450 g TNT primer.

* denotes trade mark.

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for producing a water-in-oil emulsion type explosive composition comprising combining a liquid carbonaceous fuel and an aqueous solution of at least one inorganic oxidizing salt, with agitation, in the presence of ingredients A and B, ingredient A being selected from the group consisting of oleic acid, linoleic acid and mixtures thereof, and ingredient B being selected from the group con-sisting of C1 - C6 alkylamines, C1 - C6 alkyldiamines, hydrazine, C2 - C6 alkanolamines, urea and mixtures thereof, incorporating dispersed gas bubbles into the resulting water-in-oil emulsion, one of said ingredients A and B being added before or during agitation and the remaining ingredient of ingredients A or B being added during agitation.

2. A process for producing a water-in-oil emulsion type explosive composition comprising:
a) adding a carbonaceous fuel, which is liquid at a temperature of at least 65°C or an aqueous solution of at least one inorganic oxidizing salt, to a blender;
b) agitating said aqueous solution or carbona-ceous fuel;
c) adding an emulsifier precursor ingredient to the aqueous solution or carbonaceous fuel, said precursor ingredient being selected from ingredients A and B, said ingredient A being selected from the group consisting of oleic acid, linoleic acid and mixtures thereof, said ingredient B being selected from the group consisting of C1 - C6 alkylamines, C1 - C6 alkyldiamines, hydrazine, C2 - C6 alkanol-amines and urea, and mixtures thereof;

d) adding the carbonaceous fuel or aqueous solution whichever was not added during step a);
e) adding ingredient A or ingredient B, whichever was not added during step c);
f) increasing the rate of agitation of the mix-ture of ingredients added during steps a), c), d), and e) to form a water-in-oil emulsion.

3. A method according to Claim 2 wherein further ingredients selected from fuels, explosives, gas entraining agents and solid inorganic oxidizing salts are added during any one or more of steps a) to f).

4. A method according to Claim 1 or Claim 2 wherein ingredient A is oleic acid.

5. A method according to Claim 1 or Claim 2 wherein ingrdient B is selected from monomethylamine and ethanolamine.

6. An explosive water-in-oil emulsion comprising from 5 to 22 parts by weight water, from 60 to 80 parts by weight of at least one oxidizing salt, from 2 to 10 parts by weight of a liquid carbonaceous fuel, and an emulsifier made from ingredients A and B, ingredient A being selected from the group consisting of oleic acid, linoleic acid and mixtures thereof, ingredient B being selected from the group consisting of C1 - C6 alkylamines, C1 - C6 alkyldiamines, hydrazine, C2 - C6 alkanolamines, urea and mixtures thereof, said emulsion having a density between 1.00 and 1.35 g/cm3.

7. An emulsion according to Claim 6 wherein ingredient A is oleic acid and ingredient B is selected from monomethylamine or ethanolamine.

8. An emulsion according to Claim 7 wherein the emulsion contains between about 60 to 80 wt. % of the oxidizing salt.

9. An emulsion according to Claim 7 or 8 wherein the emulsion contains between about 2 and about 10 wt. % of liquid carbonaceous fuel.