EXPLOSIVE

EXPLOSIF

English Abstract

A process for producing an ammonium nitrate fuel oil (ANFO) explosive includes admixing an oil with water to form a fuel comprising an emulsion. The emulsion is admixed with solid particulate ammonium nitrate. The emulsion is absorbed into the ammonium nitrate to form the ANFO explosive.

French Abstract

Un procédé permettant de produire un explosif de nitrate d'ammonium et d'huile (ANFO) inclut le mélange d'une huile avec de l'eau pour former un combustible comprenant une émulsion. L'émulsion est mélangée avec du nitrate d'ammonium sous forme de particules solides. L'émulsion est absorbée dans le nitrate d'ammonium pour former l'explosif ANFO.

Claims

4
CLAIMS:
1. A process for producing an ammonium nitrate fuel oil (ANFO) explosive,
the process including:
admixing an oil with water to form a fuel comprising an emulsion; and
admixing the emulsion with solid particulate ammonium nitrate to absorb the
emulsion into the ammonium nitrate to form an ANFO explosive.
2. A process according to Claim 1, wherein the oil is used lubricating oil.
3. A process according to Claim 2, wherein the used lubricating oil is that
obtained from mining vehicles.
4. A process according to any one of Claims 1 to 3 inclusive, wherein the
solid particulate ammonium nitrate is in the form of porous prills.
5. A process according to any one of Claims 1 to 4 inclusive, wherein the
relative proportions of emulsion and ammonium nitrate employed are such that,
in the
ANFO explosive, the oil forms 5-8% by mass thereof.
6. A process according to any one of Claims 1 to 5 inclusive wherein, in the
emulsion, the oil forms 55-86% by mass thereof.
7. A process according to any one of Claims 1 to 6 inclusive, wherein high-
shear mixing is used to effect the admixing of the oil with the water to form
the
emulsion.
8. A process according to any one of Claims 1 to 7 inclusive, which includes
effecting the admixing of the oil with the water to form the emulsion, in the
presence of
an emulsifier/surfactant.
9. A process according to Claim 8, wherein the emulsifier/surfactant forms
0.2-1.0% by mass of the emulsion.

10. A process according to Claim 9, wherein the emulsion/surfactant forms
0.3-0.8% by mass of the emulsion.
11. A process according to any one of Claims 1 to 10 inclusive, wherein the
admixing of the emulsion with the particulate ammonium nitrate is by pumping
the
emulsion from a source tank and spraying it by means of a nozzle on to the
particulate
ammonium nitrate which is moved along by the flutes of an auger to provide
additional
mixing, in an ammonium nitrate:emulsion ratio of 95:5-85:15.
12. An ANFO explosive when produced in accordance with the process of any
one of Claims 1 to 11 inclusive.

Description

CA 02662067 2009-02-26
WO 2008/029339 PCT/IB2007/053534
EXPLOSIVE
THIS INVENTION relates broadly to ammonium nitrate/fuel oil explosive,
also known as ANFO explosive, and hereinafter referred to as ANFO explosive.
More
particularly, the invention relates to a process for producing an ANFO
explosive, and to
an ANFO explosive when produced in accordance with the process.
According to the invention, broadly, there is provided a process for
producing an ammonium nitrate fuel oil (ANFO) explosive, the process
including:
admixing an oil with water to form a fuel comprising an emulsion; and
admixing the emulsion with solid particulate ammonium nitrate to absorb the
emulsion into the ammonium nitrate to form an ANFO explosive.
In a preferred embodiment of the invention, the oil is used lubricating oil.
More particularly, the lubricating oil may be of the type employed for the
lubrication of motor vehicles, such as utility vehicles of the kind used in
mines, or for the
lubrication of similar machinery. The particulate ammonium nitrate in turn
will typically
be in the form of porous prills of the type conventionally used for the
manufacture of
ANFO explosives.
The relative proportions of emulsion and ammonium nitrate employed will
be more or less conventional, such that, in the product ANFO explosive, the
oil forms
5-8% by mass, typically 5-7% by mass, e.g. 6% thereof. In the emulsion, the
oil may
form 55-86% by mass, preferably 72-78% by mass, e.g. 75% thereof. The balance
is
thus naturally water. Thus, when the oil forms 75% by mass of the emulsion,
water
forms 25% by mass thereof.
The emulsion may thus be either a water-in-oil emulsion or an oil-in-water
emulsion, depending on, amongst others, the relative proportions of oil and
water used.
Admixing the oil with the water to form the emulsion may be by means of
high-shear mixing, eg by using a high-shear mixer. The admixing may be
effected in

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the presence of a suitable emulsifier/surfactant, which may form 0.2-1.0% by
mass of
the emulsion, preferably 0.3-0.8%, e.g. 0.5% thereof.
While all of the emulsifier/surfactant can be added to the oil, to the water
and/or to an oil/water mixture, at least a portion of the
emulsifier/surfactant may already
be present in the oil, so that, at most, only any shortfall in the
emulsifier/surfactant is
then added to the oil, to the water or to the oil/water mixture.
Admixing the emulsion with the porous prilled ammonium nitrate (PPAN)
may be in conventional fashion by pumping the emulsion from a source tank and
spraying it by means of a nozzle on to the ammonium nitrate which is moved
along by
the flutes of an auger to provide additional mixing. To prepare the ANFO
explosive on a
batch scale, a concrete mixer or the like may be used. A PPAN:fuel ratio of
95:5-85:15,
preferably 94:6-91:9, e.g. 92:8, may be used.
The invention extends also to an ANFO explosive when produced in
accordance with the process described herein.
The invention will now be described, by way of example, with reference to
the accompanying non-limiting illustrative worked Example.
EXAMPLE
Mine utility vehicle waste lubricating oil was mixed in a high-shear mixer
with water using an emulsifier/surfactant, to form a water-in-oil emulsion.
The mixer
used was an off-the-shelf mixer marketed under the trade designation Jones
Industrial
Mixer by Jones Process Equipment as manufacturer; and the
emulsifier/surfactant used
was an off-the-shelf sorbiton monooleate made by Croda Chemicals (SA) (Pty)
Limited,
4 Covora Street, Jet Park, PO Box 1642, 1620 Kempton Park, South Africa. After
mixing the oil and water into a stable homogeneous emulsion, comprising 0.5%
by
mass emulsifier/surfactant, 24.5% by mass water and 75% by mass oil, the
emulsion
was admixed with PPAN by pumping the emulsion from a source tank and spraying
it by
means of a nozzle on to the ammonium nitrate prills which were moved along by
the

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flutes of an auger to provide additional mixing, to cause absorption of the
emulsion into
the PPAN, in a PPAN:emulsion mass ratio of 92:8. The emulsion was found to be
absorbed almost immediately into the PPAN to form an ANFO explosive.
The ANFO explosive was subjected to detonation tests in comparison with
standard ANFO explosive made from PPAN and a fuel comprising Shellsol 2325
(trademark) mining solvent, and was found to behave in comparable fashion as
far as
plate detonation tests and velocity of detonation (VOD) were concerned.
The Applicant is aware that used mine utility vehicle oil, which is
generated in large volumes, has been used in the past for the manufacture of
ANFO
explosive. However, it is refractory and difficult to absorb into PPAN by
itself, so that it
must be diluted with diesel or other virgin oil, such as the mining solvent
available in
South Africa under the trade mark Shellsol 2325 from Shell South Africa Energy
(Pty)
Limited of Shell Court, 33 Baker Street, Rosebank 2196, PO Box 747, Saxonwold
2132,
South Africa. When the ANFO explosive comprises, as is typically the case, 5-
7% by
mass fuel oil, the balance being PPAN, no more than about 2-3% of the ANFO
explosive can be waste mine utility vehicle oil, the remaining 3-4% being
required to be
virgin diesel or Shellsol. This is a disadvantage, because of the cost of the
virgin oil,
and because of the lowered consumption of used or waste oil. It is thus a
particular
advantage of the present invention that it obviates the use of any virgin oil
to dilute the
waste oil, the virgin oil being supplanted by water and economically
attractive small
amounts of emulsifier/surfactant. Disposal in this fashion of the waste oil is
thus
ecologically desirable and economically attractive.