Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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.
~q
6~
~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.
6~
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;
~3~
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.
~.2~
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
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-- 8 --
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.
