U.S. patent application number 16/468137 was filed with the patent office on 2020-01-02 for improved explosive composition.
The applicant listed for this patent is CMTE Development Limited. Invention is credited to Miguel Ulises ARAOS, Italo ONEDERRA.
Application Number | 20200002241 16/468137 |
Document ID | / |
Family ID | 62557765 |
Filed Date | 2020-01-02 |
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United States Patent
Application |
20200002241 |
Kind Code |
A1 |
ARAOS; Miguel Ulises ; et
al. |
January 2, 2020 |
IMPROVED EXPLOSIVE COMPOSITION
Abstract
The present invention provides an explosive composition
comprising from about 2 to about 25 w/w hydrogen peroxide, from
greater than 0 and up to about 90% w/w of one or more of other
oxidisers. The present invention also provides a method of 5
preparing an explosive composition and use of the explosive
composition of the invention to break and move ground, such as in
mining operations.
Inventors: |
ARAOS; Miguel Ulises;
(Jindalee, AU) ; ONEDERRA; Italo; (Pinjarra Hills,
AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CMTE Development Limited |
Pinjarra Hills, Queensland |
|
AU |
|
|
Family ID: |
62557765 |
Appl. No.: |
16/468137 |
Filed: |
December 12, 2017 |
PCT Filed: |
December 12, 2017 |
PCT NO: |
PCT/AU2017/051368 |
371 Date: |
June 10, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C06B 47/145 20130101;
C06B 21/0008 20130101; C06B 43/00 20130101; C06B 31/285 20130101;
C06B 23/003 20130101 |
International
Class: |
C06B 47/14 20060101
C06B047/14; C06B 21/00 20060101 C06B021/00; C06B 43/00 20060101
C06B043/00; C06B 23/00 20060101 C06B023/00; C06B 31/28 20060101
C06B031/28 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2016 |
AU |
2016905130 |
Claims
1. An explosive composition comprising: a. from about 2 to about
25% w/w hydrogen peroxide; and b. from greater than 0 and up to
about 90% w/w of at least one other oxidiser.
2. The explosive composition according to claim 1, wherein the at
least one other oxidiser is selected from the group consisting of
nitrate salts, perchlorate salts, sodium peroxide, potassium
peroxide and optionally nitric acid, wherein the nitrate salts are
selected from the group consisting of ammonium nitrate, calcium
ammonium nitrate, calcium nitrate and sodium nitrate, and wherein
the perchlorate salts are selected from the group consisting of
ammonium perchlorate and sodium perchlorate.
3-6. (canceled)
7. The explosive composition according to claim 1, comprising at
most 50% w/w of water.
8. (canceled)
9. The explosive composition according to claim 1, comprising from
about 5 to about 25% w/w hydrogen peroxide.
10. The explosive composition according to claim 1, comprising from
about 0.1 to about 75% w/w of the at least one other oxidiser.
11. The explosive composition according to claim 1, further
comprising at least one of an additive selected from the group
consisting of a sensitiser, fuel, secondary fuel, water, thickener,
crosslinker, emulsifier, and energy diluent.
12. (canceled)
13. The explosive composition according to claim 11, wherein the
sensitiser comprises at least one of a compressible material and
bubbles of gas, wherein the bubbles of gas are formed in situ and
consist of one of N.sub.2, O.sub.2, CO.sub.2, NO, H.sub.2 bubbles
and a mixture thereof, and wherein the compressible material is gas
entrapped material selected from the group consisting of glass
microballoons, ceramic microballoons, plastic microballoons and EPS
with a particle size smaller than 2 mm.
14. (canceled)
15. The explosive composition according to claim 13, further
comprising a sufficient amount of the sensitiser such that a
density of the explosive composition is controlled to around 0.3 to
1.4 g/cm.sup.3.
16. The explosive composition according to claim 11, wherein said
fuel is one of a water soluble fuel and a water insoluble fuel,
said water soluble fuel is selected from the group consisting of an
amine nitrate, gums, glycerol, ethylene glycol, propylene glycol,
sugar molasses, formamide, urea and a mixture thereof, and wherein
the water insoluble fuel is selected from the group consisting of
diesel, oils, vegetable oils, and mixtures thereof.
17-18. (canceled)
19. The explosive composition according to claim 1, wherein the
explosive composition is a watergel composition which comprises at
least one of a thickeners and a crosslinker, wherein the thickener
is selected from the group consisting of guar gum, xanthan gum,
sodium alginate, polyacrylamides and polyvinyl alcohols, and
wherein the crosslinker is selected from the group consisting of
antimony salts, chromic salts, phosphoric acid and mixtures
thereof.
20. (canceled)
21. The explosive composition according to claim 1, wherein the
explosive composition is an emulsion composition which comprises at
least one emulsifiers selected from the group consisting of
PIBSA-amine derivatives, SMO, lecithin and a mixture thereof.
22. The explosive composition according to claim 1, wherein the
explosive composition comprises at least one energy diluents
selected from the group consisting of EPS, crumb rubber tyre,
popcorn, and plastic beads.
23. (canceled)
24. The explosive composition according to claim 1, having an
Oxygen balance between +10 and -10.
25. The explosive composition according to claim 1, having a
viscosity of from 5 to 50 Pa*s.
26-58. (canceled)
59. A method of breaking and moving ground comprising steps of:
applying the explosive composition according to claim 1 to a
blasthole; and detonating the explosive composition.
Description
[0001] This application claims priority to and the benefit of
Australian provisional patent application no. 2016905130 dated 12
Dec. 2016, which is incorporated herein by cross-reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to an improved explosive
composition. More particularly, the invention relates to an
explosive composition comprising hydrogen peroxide (HP) in
combination with one or more other oxidisers.
[0003] The invention has been developed primarily for use as a
hydrogen peroxide/nitrate salt-based explosive composition for use
in mining applications and will be described hereinafter with
reference to this application. However, it will be appreciated that
the invention is not limited to this particular field of use.
BACKGROUND OF THE INVENTION
[0004] The following discussion of the prior art is provided to
place the invention in an appropriate technical context and enable
the advantages of it to be more fully understood. It should be
appreciated, however, that any discussion of the prior art
throughout the specification should not be considered as an express
or implied admission that such prior art is widely known or forms
part of common general knowledge in the field.
[0005] Nearly all commercial and mining explosives used in the
world today are based on ammonium nitrate (AN) or combinations of
AN with smaller quantities of other alkaline and/or alkaline earth
nitrate salts, e.g. sodium nitrate (SN) or calcium nitrate (CN).
AN, which is a strong oxidiser, has been used as the base of
commercial explosives for at least the last 50-60 years. Most
explosives of this type rely on the energetic reaction of nitrogen
compounds incorporated within the explosive to provide the
necessary explosive power.
[0006] Initially, mining companies used AN as an explosive on its
own. However, they soon realised that the addition of diesel
increased the energy output without a large increase on costs
(ammonium nitrate--fuel oil, now commonly referred to as `ANFO`).
However, the water resistance of ANFO is quite poor, which limited
its use in wet blast holes. To ameliorate this issue, slurries and
watergels were developed. Slurries typically comprise AN
dissolved/dispersed in water, and other salts such as calcium
nitrate, sodium nitrate, amine nitrates, perchlorates, etc. and
other additives such as guar gum (as thickener) and water soluble
or insoluble fuels (glycerol, MMAN, diesel, etc). They can also be
blended with ANFO depending on the characteristics of the ground
being blasted. Slurries also typically include solid sensitisers
(aluminium and high explosives such as TNT, RDX, etc) to enable the
slurry to detonate and to minimise misfires. Watergels have similar
compositions to slurries, however, crosslinkers can be added to
enhance the water resistance of the product.
[0007] One of the drawbacks of watergels and slurries is that there
is a limit of AN which can be incorporated into the solution. This
drawback was overcome by the development of water-in-oil emulsions.
These emulsions can contain AN in high concentration (see U.S. Pat.
No. 3,447,978) as emulsions are manufactured at high temperatures.
Water-in-oil emulsions are made of a hot aqueous phase (composed of
AN, other nitrate salts, perchlorate salts, etc.) dispersed into an
organic fuel. The aqueous--organic mixture is stabilised by the use
of an emulsifier. Emulsions can also be blended with ANFO in
different ratios so suit the ground to be blasted.
[0008] Despite the development of AN emulsions, AN slurries, and
watergels, however, there is still a need to develop improved
explosives, which are suitably more cost effective compared to
existing explosive compositions and are capable of being produced
in large quantities to meet the high demand from industry. It would
be advantageous to use less AN in the formulation and instead use
other types of nitrates to provide alternatives to the usage of AN.
Additionally, such substitutes should preferably be safer, have a
relatively low carbon footprint, manufactured nearby the point of
use to minimise the transport on public roads, able to be
manufactured on an as-needs basis to minimise the need for
stockpiling and to increase safety, allow for the use of existing
delivery equipment, and/or produce a lower amount of (or no) toxic
nitrogen oxide fumes (NO.sub.x) upon detonation, etc. It would also
be ideal if there are no onerous regulatory requirements for such a
substitute, thereby reducing administrative costs. It would also be
preferable for the explosive composition to be crosslinkable
in-situ to increase viscosity down the blasthole.
[0009] Despite the advances on the types of compositions that can
be manufactured from ammonium nitrate, one of the disadvantages is
that during the detonation NO.sub.x fumes can be generated, due to
the presence of nitrogen compounds in the explosive composition
(from nitrates). These NO.sub.x fumes are toxic and can affect the
health of mine site personnel. Therefore the emission of NO.sub.x
fume after blasting is a safety issue and, in countries like
Australia, there are now strict regulatory controls in place to
manage such emissions. See for example "Queensland Guidance Note:
Management of oxides of nitrogen in open cut blasting" issued by
the regulator in Queensland, Australia, 2011. Likewise, explosive
manufacturers in Australia have also issued a code of practice to
manage the NO.sub.x fumes after blasting (AEISG Code of Practice,
Prevention and Management of Blast Generated NO.sub.x Gases in
Surface Blasting, 2011). Therefore, there is a need to find
explosive compositions that substantially reduce the production of
NO.sub.x.
[0010] One material that is also an oxidiser and that has the
potential to meet at least some of these needs is hydrogen peroxide
(HP).
[0011] International PCT publication WO 2013/013272 describes an
explosive composition comprising HP and a sensitiser, wherein the
sensitiser comprises a compressible material having one or more
gas-filled voids and/or bubbles of gas. WO 2013/013272 also
describes a method of preparing an explosive composition comprising
combining hydrogen peroxide and a sensitiser, wherein the
sensitiser comprises a compressible material and/or bubbles of gas,
and use of said explosive composition. The compositions of WO
2013/013272 may contain a very high concentration of HP. Despite
prior art examples of HP-based explosives, there is still a need to
develop improved explosive compositions. In particular, there is a
need to develop improved explosive compositions made from HP and
one or more other oxidisers in which the sensitivity, density,
velocity of detonation (VOD) and the delivery of the energy can be
controlled.
[0012] It is an object of the present invention to overcome or
ameliorate one or more of the disadvantages of the prior art, or at
least to provide a useful alternative.
SUMMARY OF THE INVENTION
[0013] The present invention relates to explosives for use in
commercial, construction, civil, agriculture, mining, and similar
fields. However, it will be appreciated that the invention could be
utilised in other related fields.
[0014] A preferred objective of an embodiment of the present
invention is to provide an explosive composition which meets one or
more of the following objectives: is conveniently prepared, has
improved stability over time in situ, can use large amounts of
sustainable fuels (which lowers the carbon footprint of the
explosive), and can use large amount of nitrates other than AN
(which lowers the dependency on AN).
[0015] According to a first aspect the present invention provides
an explosive composition comprising:
[0016] a. from about 2 to about 25% w/w hydrogen peroxide; and
[0017] b. from greater than 0 and up to about 90% w/w one or more
other oxidisers.
[0018] In one embodiment, there is provided an explosive
composition comprising: [0019] from about 2 to about 25% w/w
hydrogen peroxide; and [0020] from greater than 0 and up to about
90% w/w of one or more of other oxidisers; and [0021] from about 15
to about 25% w/w of fuels, preferably sustainable fuels.
[0022] According to a preferred embodiment, the present invention
provides an explosive composition comprising: [0023] from about 2
to about 25% w/w hydrogen peroxide; [0024] from greater than 0 and
up to about 90% w/w of one or more other oxidisers; [0025] a fuel
phase; [0026] a thickener and/or crosslinker; [0027] a secondary
fuel; and [0028] a sensitiser.
[0029] Preferably the composition comprises from about 5 to about
25% w/w hydrogen peroxide. Preferably the one or more other
oxidiser(s) is a salt or acid selected from the group consisting of
nitrate salts, perchlorate salts, peroxide salts, or nitric acid.
For example, the one or more other oxidisers may be selected from
the group consisting of nitrate salts, perchlorate salts, sodium
peroxide, potassium peroxide and optionally nitric acid. The
perchlorate salts may be selected from ammonium perchlorate and
sodium perchlorate. Preferably the salts are selected from ammonium
nitrate (AN), calcium nitrate (CN), calcium ammonium nitrate (CAN),
sodium nitrate (SN), NH.sub.4ClO.sub.4, NaClO.sub.4,
Na.sub.2O.sub.2, K.sub.2O.sub.2 or mixtures thereof. For example,
the nitrate salts may be selected from ammonium nitrate, calcium
nitrate and sodium nitrate. By way of further example, the nitrate
salts may be selected from calcium ammonium nitrate, calcium
nitrate and sodium nitrate. In one embodiment, the explosive
composition is devoid of AN. The one or more other oxidisers in the
explosive composition may be selected from calcium nitrate and
sodium nitrate. Preferably the explosive composition contains from
0.1 to 75% w/w of one or more other oxidisers. In one embodiment,
the explosive composition contains from 0.1 to 75% w/w of dissolved
salts. In a preferred embodiment, at least some of at least one of
the one or more other oxidisers is not fully dissolved in the
explosive composition but is present as a solid oxidiser, e.g., in
the form of powder or prills. In such an embodiment, the one or
more other oxidisers that is at least partially present as a solid
may be selected from the group consisting of AN, SN, CN, CAN, or
mixtures thereof. The composition may comprise a solid nitrate
oxidiser, for example, in an amount of from contains from 0.1 to
70% w/w. The composition may comprise water. The solid nitrate
oxidiser may be selected from the group of AN, SN, CAN or mixtures
thereof.
[0030] Preferably the composition comprises 50% w/w or less of
water, or 30% w/w or less of water, or 25% w/w or less of water.
The explosive composition may further comprise one or more other
components selected from the group consisting of sensitisers,
fuels, secondary fuels, water, thickeners, crosslinkers,
emulsifiers, energy diluents and optionally other additives.
[0031] Preferably the explosive composition comprises a sensitiser.
Preferably the sensitiser comprises a compressible material and/or
bubbles of gas, or comprises a gas entrapped material. The bubbles
of gas may be formed in situ and consist of N.sub.2, O.sub.2,
CO.sub.2, NO.sub.x or H.sub.2 bubbles or a mixture thereof. The gas
entrapped material may be selected from glass microballoons,
ceramic microballoons, plastic microballoons or EPS with a particle
size smaller than 2 mm. The explosive composition preferably has a
density controlled by adding a sufficient amount of sensitiser such
that the composition is detonation-sensitive. The density may be
controlled to around 0.3 to 1.4 g/cm.sup.3, or may be formulated to
around 0.3 to 1.4 g/cm.sup.3.
[0032] The composition may comprise a fuel, or it may comprise a
fuel and a secondary fuel. The fuel may be a water soluble fuel.
The water soluble fuel may be selected from an amine nitrate or
urea or a mixture thereof. The explosive composition may contain
from 0.1 to 30% w/w of water soluble fuel. The composition may
contain between 13-25% w/w of the fuel phase. Preferably the fuel
phase comprises one or more components selected from the group
consisting of gums, glycerol, ethylene glycol, propylene glycol,
sugar molasses, formamide or mixtures thereof. For example, the
fuel phase may comprise one or more components selected from the
group consisting of gums, glycerol, ethylene glycol, propylene
glycol, formamide or mixtures thereof. The composition may comprise
a sustainable fuel. The sustainable fuel may be present in the
composition in an amount of between 15 and 25% w/w.
[0033] Preferably the composition is a watergel composition, in
which case the composition may comprise a thickener or crosslinker.
The composition may be a watergel composition comprising a
thickener and a crosslinker. The thickener may be suspended in the
fuel. The thickener may be selected from the group consisting of
guar gum, xanthan gum, sodium alginate, polyacrylamides, and
polyvinyl alcohols. The composition may comprise a crosslinker
selected from the group of antimony salts, chromic salts,
phosphoric acid or mixtures thereof. The fuel phase may comprise
one or more water insoluble fuels selected from the group
consisting of diesel, oils, vegetable oils, or mixtures thereof.
Accordingly, the explosive composition may be formulated as an
emulsion, in which case it may comprise an emulsifier. The
emulsifier may be mixed in the fuel. The emulsifier may be selected
from the group consisting of PIBSA-amine derivatives, SMO, lecithin
or a mixture thereof.
[0034] Preferably the composition is formulated to have an oxygen
balance between +10 to -10, e.g., the composition may have an
oxygen balance of between +5 and -5. The explosive composition may
contain from 1 to 800% v/v of an energy reducing agent (i.e.,
diluent material). The energy diluent material may be selected from
the group consisting of EPS, crumb rubber tyre, popcorn, and
plastic beads. The hydrogen peroxide, one or more other oxidisers
and a fuel containing thickeners may be mixed until a thick
material is formed, with a viscosity between 5-50 Pa*s. The
composition may have a viscosity of from 5 to 50 Pa*s.
[0035] Many advantages result from the inventive explosive
compositions taught herein. For example, certain formulations of
the compositions of the invention may be more convenient to
prepare, more cost effective compared to existing explosive
compositions, safer to produce and to store, and/or capable of
being produced in large quantities to meet the demand from the
mining industry. Added safety is provided by the use of, for
example, relatively high concentrations of CAN, which is known to
be less sensitive to unintended detonation than AN. The same
applies the use of SN in the formula. The present invention is
therefore a significant advance in the art. The explosive
compositions of the invention utilise HP, which is a
sustainably-produced material that has a relatively low carbon
footprint compared to other types oxidisers used in the art. The
composition may also use sustainable fuels, as opposed to current
technology used in the mining industry. To explain, current
explosive compositions use a low concentration of fuel, which is
typically sourced from the petrochemical industry. In contrast, the
inventive explosive compositions disclosed herein are able to
incorporate relatively higher amounts of sustainable fuel than
commercially available or prior art explosive compositions.
Accordingly, the lower reliance on fuels from the petrochemical
industry is a significant advance in the art. Additionally the
increase of sustainable fuels in the formulation means that the
amount of oxidiser material in the formulation can be decreased
without affecting the detonation properties.
[0036] The present invention is counterintuitive to the common
knowledge in the art. To explain, it is currently believed that it
is impossible or very difficult to detonate a composition that has
a relatively high concentration of nitrates, such as CAN. However,
surprisingly, the present invention provides the ability to
detonate compositions that contain up to 30% w/w of CAN, and even
up to 65% w/w. This aspect of the present invention is a
significant advance in the art. The present invention also provides
the ability to incorporate a relatively high amount of nitrates by
making a watergel or emulsion, which already comprises HP/nitrate
in the aqueous phase, with a further solid nitrate phase in the
form of prills. Use of oxidiser in solid form enables some control
over the density of the overall composition, and therefore provides
some control over the VOD, as will be discussed below.
[0037] The explosive compositions of the invention may also be
formulated into emulsion form. It will also be appreciated that the
inventive compositions of the invention may produce low amounts of
NO.sub.x, and in some forms of the invention no NO.sub.x at
all.
[0038] The compositions of the invention are contemplated to
provide several advantages over the prior art, such as better
stability over time than explosive compositions comprising a higher
percentage of HP. This is advantageous in the context of both
safety and storage. More specifically, the "sleeping time" (i.e.
the time over which an explosive deteriorates in situ such that its
velocity of detonation decreases below a defined useful limit of
such an explosive composition when it is in contact with rocks) is
expected to be greater than an explosive comprising a higher
percentage of HP. By way of example, a CAN/HP composition according
to the invention has been made and found to have a sleeping time
that is comparable/compatible for application in a commercially
viable product, for example, a sleeping time beyond 24 hours or
more. It is therefore contemplated that larger blasts are possible
because there is a longer time (e.g. several days) over which
explosives can be loaded into many holes before the first-loaded
explosive becomes unstable in its hole. More holes can therefore be
loaded before detonation.
[0039] Another advantage is that these compositions detonate when
CAN is used. This is unexpected because CAN is not easy to
detonate. Accordingly, given the relatively reduced propensity for
CAN to detonate (compared to AN), the inventors contemplate that
there are safety advantages in using combinations of CAN and CAN/SN
compared to AN-based explosives with CN and SN additions.
[0040] According to a second aspect the present invention provides
a method of preparing an explosive composition according to the
first aspect, the method comprising combining hydrogen peroxide and
one or more other oxidisers, optionally further comprising
sensitisation of the composition. Preferably the hydrogen peroxide,
other oxidiser(s) and fuel are mixed until a thick material is
formed, with a viscosity between about 5 to 50 Pa*s. Preferably the
density of the composition is controlled by adding a sufficient
amount of sensitiser such that the composition is
detonation-sensitive.
[0041] According to a third aspect the present invention provides
use of an explosive composition according to the first aspect to
break and move ground, e.g. in mining operations.
Definitions
[0042] In describing and claiming the present invention, the
following terminology will be used in accordance with the
definitions set out below. It is also to be understood that the
terminology used herein is for the purpose of describing particular
embodiments of the invention only and is not intended to be
limiting. Unless defined otherwise, all technical and scientific
terms used herein have the same meaning as commonly understood by
one having ordinary skill in the art to which the invention
pertains.
[0043] Unless the context clearly requires otherwise, throughout
the description and the claims, the words `comprise`, `comprising`,
and the like are to be construed in an inclusive sense as opposed
to an exclusive or exhaustive sense; that is to say, in the sense
of `including, but not limited to`.
[0044] Other than in the operating examples, or where otherwise
indicated, all numbers expressing quantities of ingredients or
reaction conditions used herein are to be understood as modified in
all instances by the term `about`. The examples are not intended to
limit the scope of the invention. In what follows, or where
otherwise indicated, `%` will mean `weight %`, `ratio` will mean
`weight ratio` and `parts` will mean `weight parts`.
[0045] Unless the context clearly indicates otherwise, all
references to a component being present at a certain % w/w are with
respect to the entire explosive composition. For example, an
explosive composition comprising 2-25% w/w hydrogen peroxide refers
to an explosive composition comprising 2-25 g hydrogen peroxide per
100 g of the explosive composition.
[0046] The term HP is an abbreviation for hydrogen peroxide.
[0047] The term AN means ammonium nitrate.
[0048] CN means calcium nitrate tetra hydrate.
[0049] CAN means calcium ammonium nitrate
[0050] SN is an abbreviation for sodium nitrate.
[0051] ANFO is an abbreviation for ammonium nitrate fuel oil.
[0052] Amine nitrates is an abbreviation for monomethylamine or
ethyl amine or propyl amine nitrate.
[0053] Sensitiser means an additive that introduces voids in the
composition. Sensitisers can increase the sensitivity to detonation
of energetic materials. The sensitiser can be chemically generated
voids (gas bubbles) or can enclose or entrap a gas (examples of
which include ceramic/glass microballoons, EPS and polyurethane
foams).
[0054] GMB is an abbreviation for glass micro balloons.
[0055] EPS is an abbreviation for expanded polystyrene.
[0056] TNT means trinitrotoluene.
[0057] HMX refers to
octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine.
[0058] RDX refers to 1,3,5-trinitroperhydro-1,3,5-triazine.
[0059] VOD refers to velocity of detonation in m/sec.
[0060] OB means oxygen balance.
[0061] The term g/cm.sup.3 is has the same meaning as g/ml.
[0062] The terms `preferred`, `preferably` and `suitably` refer to
embodiments of the invention that may afford certain benefits,
under certain circumstances. However, other embodiments may also be
preferred, under the same or other circumstances. Furthermore, the
recitation of one or more preferred embodiments does not imply that
other embodiments are not useful, and is not intended to exclude
other embodiments from the scope of the invention.
[0063] The terms `a`, `an` and `the` mean `one or more`, unless
expressly specified otherwise. The terms `an embodiment`,
`embodiment`, `embodiments`, `the embodiment`, `the embodiments`,
`an embodiment`, `some embodiments`, `an example embodiment`, `at
least one embodiment`, `one or more embodiments` and `one
embodiment` mean `one or more (but not necessarily all) embodiments
of the present invention(s)` unless expressly specified
otherwise.
[0064] The prior art referred to in this specification is
incorporated herein by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0065] FIG. 1 is a graph plotting VOD against density for an
approximate 20% HP and approximate 40% CAN/fuel-based gel in a 50
mm diameter pipe. Sensitization was achieved by the addition of a
gassing agent that decomposed HP to O.sub.2 bubbles.
[0066] FIG. 2 is a graph plotting VOD against density for a blend
made with approximately 6% HP and approximate 65% CAN/fuel-based
gel and CAN prill in a ratio 45:55 (gel:prill) in a 102 mm diameter
pipe. Sensitization was achieved by the addition of a gassing agent
that decomposed HP to O.sub.2 bubbles.
[0067] FIG. 3 is a graph plotting VOD against density for an
approximate 30% HP and approximate 24% SN/fuel-based gel in a 50 mm
diameter pipe. Sensitization was achieved by the addition of a
gassing agent that decomposed HP to O.sub.2 bubbles.
[0068] FIG. 4 is a graph plotting VOD against density for a blend
made with approximately 16% HP and approximate 44% SN/fuel-based
gel and SN prill in a ratio 70:30 (gel:prill) and in a 102 mm
diameter pipe. Sensitization was achieved by the addition of a
gassing agent that decomposed HP to O.sub.2 bubbles.
DETAILED DESCRIPTION OF THE INVENTION
[0069] According to a first aspect, the present invention provides
an explosive composition comprising: [0070] from about 2 to about
25% w/w hydrogen peroxide; and [0071] from greater than 0 and up to
about 90% w/w of one or more other oxidisers.
[0072] Suitably the composition further comprises one or more other
components selected from the group consisting of sensitisers,
fuels, other fuels, water, thickeners, crosslinkers, emulsifiers,
energy diluents and optionally other additives as discussed further
below.
Hydrogen Peroxide (HP)
[0073] The concentration of HP in the composition of the invention
is between about 2% to 25% w/w.
[0074] Suitably the HP concentration in the composition is about
0.5, 0.8, 1, 2, 5, 6, 10, 12, 13, 15, 20 or 25% w/w. For example,
the HP concentration in the composition may be between about 0.5,
0.8, 1, 2, 5, 6, 10, 12, 13, 15, or 20 and 25% w/w. For example,
the HP concentration in the composition may be greater than 1% but
less than 25%, or may be greater than 2% but less than 25%, or may
be greater than 5% but less than 25% w/w. Suitably the HP
concentration in the composition is thus around between about 1 to
5, 2 to 5, 1 to 10, 5 to 10, 5 to 6, 6 to 10, 5 to 15, 10 to 12, 12
to 13, 13 to 15, 2 to 20, 5 to 20, 15 to 25, 15 to 20 or 2 to 25, 5
to 25, or 20 to 25% w/w. For example, the HP concentration in the
composition may be from 2 to 10% w/w, or from 12 to 25% w/w, or
from 10 to 20% w/w.
[0075] It will be understood that the % w/w of hydrogen peroxide
present in the composition refers the amount of pure hydrogen
peroxide. As hydrogen peroxide is provided in the form of an
aqueous solution having an HP concentration of less than 100%, for
example, having an HP concentration of 50% w/w, or 35% w/w, or 30%
w/w, the skilled person will readily understand the need and manner
by which they can adjust the amount of diluted HP solution required
to ensure the explosive compositions of the invention comprise 2 to
25% w/w HP. To take an example for the avoidance of doubt, if a
composition of the invention contains 20% of a 50% w/w solution of
HP, the composition contains 10% w/w HP. The skilled person will
also appreciate that the 2 to 25% w/w concentration of HP is the
final HP concentration in the explosive composition, and thus
account must be taken of the diluting effects of any other
components (e.g., fuels, oxidisers, thickeners, etc.) added to the
composition during formulation.
Other Oxidisers
[0076] The compositions described herein comprise one or more other
substances or mixtures of substances which are themselves suitable
as explosive materials.
[0077] In particular, the explosive compositions of the invention
comprise one or more other oxidisers (e.g. one other oxidiser, e.g.
two other oxidisers). Any suitable oxidiser can be used. For
example, the one or more other oxidiser(s) are suitably selected
from the group consisting of nitrate salts, perchlorate salts,
sodium peroxide and potassium peroxide and optionally nitric
acid.
[0078] The nitrate salts may be selected from the group consisting
of ammonium nitrate, sodium nitrate, calcium ammonium nitrate,
calcium nitrate, potassium nitrate, barium nitrate and magnesium
nitrate.
[0079] The perchlorate salts may be selected from the group
consisting of ammonium perchlorate, sodium perchlorate, potassium
perchlorate, barium perchlorate, magnesium perchlorate and calcium
perchlorate (e.g. ammonium perchlorate and sodium perchlorate).
[0080] In one embodiment the one or more other oxidiser(s) are
selected from the group consisting of nitrate salts and perchlorate
salts. In one embodiment the one or more other oxidiser(s) are
selected from nitrate salts. In one embodiment the one or more
other oxidiser(s) are selected from the group consisting of AN, CAN
and SN. In one embodiment the one or more other oxidiser(s) are
selected from the group consisting of CAN, CN and SN. In one
embodiment the one or more other oxidiser(s) are selected from the
group consisting of CAN and SN. In one embodiment the other
oxidiser is CAN. In one embodiment the other oxidiser is SN. In one
embodiment the other oxidiser is CN. In one embodiment, the one or
more other oxidiser(s) do not include AN. In other words, in one
embodiment, the explosive composition is devoid of AN.
[0081] The compositions of the invention comprise from greater than
0 and up to about 90% w/w of one or more other oxidisers, such as
from about 0.1% to about 75% w/w. For example, compositions of the
invention may comprise from greater than 0, from 0.1%, from 1%,
from 10%, from 20%, from 30%, from 40%, from 50%, or from 60% w/w
up to 90% w/w of one or more other oxidisers, e.g., compositions of
the invention may comprise from 1 to 20%, from 20 to 40%, from 15
to 35%, from 35 to 55%, from 30 to 70%, from 40 to 70%, or from 50
to 80% w/w of the one or more other oxidisers. For example,
compositions of the invention may comprise up to 90%, 80%, 75%,
70%, 65%, 60%, 50%, 40%, 30%, 20% w/w, etc of one or more other
oxidisers, or may comprise about 90%, 80%, 75%, 70%, 65%, 60%, 55%,
50%, 45%, 40%, 30%, or 20% w/w of one or more other oxidisers. It
will be understood that the explosive compositions herein comprise
one or more oxidisers according to the foregoing amounts or ranges
in total, and as such, where more than one oxidiser is used, each
oxidiser may be present in any suitable amount within the foregoing
amounts or ranges such that the total mass of the oxidisers adds up
to the specified amount or range.
[0082] It will be appreciated that the oxidiser can be in the form
of a mixture of solid and liquids. To explain, typically the
oxidiser will be solubilised in water when used at a relatively low
concentration, and if present at higher concentrations beyond the
solubility of the oxidiser, then the oxidiser will be solubilised
and in a solid form. In some embodiments, the oxidiser is fully
solubilised (or substantially fully solubilised) in the
composition. In such embodiments, excess solid oxidiser, e.g., in
the form of prills, may be added. In other embodiments, the
oxidiser is only partially solubilised in the composition, in which
case solid oxidiser (e.g., in the form of solid prills) may be
added just prior to detonation such that there is insufficient time
for the prills to solubilise substantially. The oxidiser can be in
a liquid:solid ratio of between 100:0 to 20:80, and any ratio in
between. For example, the liquid:solid ratio may be between 100:0
and 70:30, or between 80:20 and 60:40, or between 70:30 and 40:60,
or between 5:50 and 30:70, or of 100:0, 70:30, 60:40, 50:50, 45:55,
40:60; or 20:80.
[0083] It also lies within the invention to have as a further
explosive component of the composition well known explosive
materials comprising one or more of for example trinitrotoluene,
nitroglycerine or pentaerythritol tetranitrate.
Water
[0084] The explosive compositions described herein may comprise
water. In one embodiment, the explosive composition may comprise
less than 50% w/w of water, or 40% w/w or less or water, or 30% w/w
or less of water, for example 25% w/w or less, 20% w/w or less, 15%
w/w or less or 10% w/w or less. In one embodiment, the explosive
composition may comprise 5% w/w or more of water, for example 10%
w/w or more. The composition may thus comprise between 5 and 50%
w/w water, or between 5 and 20% w/w water, or between 15 and 30%
w/w water, or between 10 and 40% w/w water, or 50, 45, 40, 35, 30,
25, 20, 15, 10, 5 or 1% w/w water.
Sensitisers
[0085] The explosive composition according to the invention may
comprise one or more sensitisers dispersed in the composition to
produce voids which improve sensitivity to detonation. In addition,
HP may itself act as both a sensitiser and an oxidiser.
Alternatively, HP itself may act as the sensitiser and no other
sensitisers may be used.
[0086] Suitably the explosive composition of the invention is
adapted to retain the sensitiser in a substantially homogenous
dispersion (e.g. by a thickener or an emulsifier in the case of a
watergel or an emulsion, respectively). It will be appreciated that
a variety of techniques can be utilised to achieve this property,
as discussed further below.
[0087] Suitably a minimum concentration of sensitiser is included
into the composition to cause it to be explosive. Suitably the
sensitiser is included in a detonation-sensitive concentration or
amount. The sensitiser is also suitably maintained in a
detonation-sensitive dispersion/distribution throughout the
composition. Suitably the final density of the composition is
controlled into a preferred pre-determined explosive range.
Suitably the final density is controlled with sensitiser to around
0.3 to 1.4 g/cm.sup.3. Suitably the density of the composition is
formulated to be around 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1,
1.2, 1.3, or 1.4 g/cm.sup.3. Suitably the final density of the
composition is formulated to be between around 0.3 to 0.4, 0.4 to
0.5, 0.5 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 0.9, 0.9 to 1.0,
1.0 to 1.1, 1.1 to 1.2, 1.2 to 1.3, or 1.3 to 1.4 g/cm.sup.3.
[0088] The skilled person will appreciate that a mathematical
conversion will be required to convert the weight of
ceramic/glass/plastic micro balloons or the amount of chemical to
be decomposed into bubbles to yield a certain density, to volume
(for gas bubbles). However, irrespective of the type of
sensitisation, it will be appreciated that the final density is
controlled to a predetermined value to yield an explosive
composition and to thereby control the parameters discussed
above.
[0089] Once the explosive is sensitised, it can be easily initiated
by a primer, which as the skilled person will be aware is an
explosive which generates a high detonation pressure which then
initiates detonation of the sensitised explosive.
[0090] The introduction of voids into the composition can be
provided by a variety of techniques (by entrapping gas bubbles when
mixing, by using gas bubbles chemically generated in situ, by
injecting gas bubbles, or mixing the composition with gas entrapped
material), which are all applicable to the present invention.
[0091] In one embodiment the bubbles may be `trapped` during the
preparation of the explosive composition by the mechanical mixing.
In U.S. Pat. No. 3,400,026 a formulation which uses protein in
solution (albumin, collagen, soy protein, etc.) in order to favour
the formation of bubbles and their stabilization is described. U.S.
Pat. No. 3,582,411 describes a watergel explosive formulation which
contains a foaming agent of the guar gum type modified by hydroxy
groups. In U.S. Pat. No. 3,678,140 a process for the incorporation
of air by means of the use of protein solution is described, by
passing the composition through a series of openings at pressures
from 40 to 200 psi and simultaneously introducing air through
eductors.
[0092] Wherein in situ generation of gas bubbles is provided by the
decomposition of chemicals compounds, the decomposition suitably
produces O.sub.2, CO.sub.2, N.sub.2, H.sub.2, NO or combinations
thereof.
[0093] Various gases in bubble form have been used to sensitise
blasting agents, for example nitrogen (see U.S. Pat. Nos.
3,713,919, 3,886,010, 4,875,951; 4,305,766; and 3,390,030), carbon
dioxide (see U.S. Pat. Nos. 3,288,658 and 3,390,032), oxygen (see
U.S. Pat. Nos. 3,706,607; 3,790,415, 5,397,399; 4,081,299 and
3,617,401), and hydrogen (see U.S. Pat. No. 3,711,345).
[0094] Suitable chemicals for the in situ generation of gas bubbles
include HP itself which can be decomposed with manganese (Mn)
salts, yeast, iodide salts, etc; nitrogen-based compounds such as
nitrosoamines, such as, for example,
N,N'-dinitrosopentamethylenetetramine; boron-based compounds such
as, for example, sodium borohydride; carbonates such as, for
example, sodium carbonate.
[0095] The discontinuous phase of fine gas bubbles may be
incorporated into the compositions of the present invention by
injection/bubbling the gas through the composition. It is known to
directly inject air or gas into the explosive mixture (see for
example U.S. Pat. Nos. 6,537,399; 3,582,411 and 3,642,547).
[0096] Suitable gases for injection include air, oxygen, nitrogen,
carbon dioxide, hydrogen, NO and noble gases (such as Argon).
[0097] Alternatively, hollow gas-filled compressible particles such
as micro balloons, or porous particles, or expanded polystyrene
(EPS) or mixtures thereof are included. In related embodiments the
compressible material is any low density material which has a
specific gravity <1.0 g/cm.sup.3. In brief summary, examples of
glass balloons can be seen in U.S. Pat. Nos. 4,326,900 and
3,447,978, and plastic micro balloons in U.S. Pat. Nos. 4,820,361
and 4,547,234. These balloons are typically 0.05 mm in diameter and
have a bulk density of 100 g/L. Use of expanded polystyrene can be
seen for example in U.S. Pat. Nos. 5,470,407 and 5,271,779.
[0098] In one embodiment, the compressible material is gas-filled
and selected from small hollow microspheres of ceramic, glass or
resinous materials or porous materials, and combinations thereof,
such as perlite or fly ash.
[0099] Suitably the microspheres/micro balloons contain gas such as
pentane, etc. Suitably the microspheres are sized between about 20
to 2000 micron and have a bulk density of less than 1000 g/L.
[0100] In alternative embodiments, the compressible material is a
cellular material, such as expanded polystyrene (EPS), polyurethane
foam, cotton seeds, expanded pop corn, husks, and combinations
thereof.
[0101] Examples of suitable hollow particles include small hollow
microspheres of ceramic, glass and resinous materials such as
phenol-formaldehyde, poly(vinylidene chloride)/poly(acrylonitrile)
copolymers and ureaformaldehyde. Examples of suitable hollow
particles include Q-Cel, Envirospheres.RTM., Cenospheres.RTM.,
Expancel.RTM., 3M, Extendospheres.RTM., etc. Examples of porous
materials include expanded minerals such as perlite, fly ash. A
further example of a porous material is hollow particles that are a
by-product of coal fired power stations.
[0102] Typically, sufficient bubbles and/or hollow particles and/or
porous particles are used in the compositions of the present
invention to give an explosive composition having a density in the
range of from 0.3 to 1.4 g/cm.sup.3.
[0103] For example, an explosive composition of the invention may
have a density of up to 1.4 g/cm.sup.3, up to 1.3 g/cm.sup.3, up to
1.2 g/cm.sup.3, up to 1.1 g/cm.sup.3, up to 1.0 g/cm.sup.3, etc. An
explosive composition of the invention may have a density of from
0.3 g/cm.sup.3, from 0.4 g/cm.sup.3, from 0.5 g/cm.sup.3, etc.
Using conventional mixing techniques to provide bubbles in emulsion
explosive compositions often produce bubbles with a range of bubble
sizes. For example, the bubbles often have diameters up to 2000
microns and average bubble diameters of less than 300 microns are
also common. By choice of suitable surfactants bubbles of smaller
or larger diameters can be produced. Thus by choice of an
appropriate surfactant at a desired concentration the mean gas
bubble diameter in the discontinuous gas phase may be controlled,
and bubbles of 50 to 300 microns are possible. For emulsified
explosives the density range is suitably around 0.60-1.30
g/cm.sup.3, and for watergels the density range is suitably between
0.2-1.40 g/cm.sup.3. In an emulsified system the gas bubbles are
suitably 10-100 times larger than the disperse phase droplets. The
oily phase is likely to be in contact the gas bubble, whereas the
oxidiser (or discontinuous phase) does not.
[0104] Other types of sensitising materials can be used in the
compositions of the invention, e.g. TNT, HMX, RDX, aluminium powder
and silicon powder and combinations thereof (e.g. TNT, HMX, RDX and
aluminium powder and combinations thereof).
Fuels for Watergels
[0105] The explosive compositions of the invention may comprise one
or more fuels.
[0106] HP-based watergels can be prepared with either
water-miscible or water immiscible fuels.
[0107] The skilled person will appreciate that there are many
options available for use as a fuel. For example, depending on
their origin, the fuel may be a product of vegetable origin, such
as sugars, molasses, vegetable oils or alcohols. Such fuels may be
regarded as sustainable fuels. Other fuels can be sourced from the
petrochemical industry, as for example diesel, paraffinic oils or
mineral oil, organic acids, ethers, esters, amine nitrates, urea,
hexamine, etc. Other fuels may be silicone oils, etc. Suitable
fuels for use in the compositions of the invention are glycerol,
sugar, syrup, alcohol, carbon, ground coal, waxes, oils such as
corn, cottonseed, olive, peanut, or fatty acid oils. Suitable
sustainable fuels for use in the compositions of the invention may
include, sugar molasses, vegetable oil, alcohol, oils such as corn,
cottonseed, olive, peanut, fatty acid oils, or gums. Other fuels
may be selected from ethylene glycol, glycerol, propylene glycol,
and/or formamide Preferably, the sustainable fuel is glycerol. The
composition may comprise between 15 and 25% w/w sustainable fuel,
e.g., between 15 and 20%, or between 20 and 25% w/w. The
composition may alternatively comprise less than 40% w/w
sustainable fuel, less than 30%, less than 25%, or less than 20%
w/w sustainable fuel, e.g., 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%
w/w sustainable fuel. Alternatively, the above fuels can also split
into water-soluble and water-insoluble fuels. Water-miscible fuels
which can be used with the present invention can be selected from
the group consisting of: glycerol, sugar, amine nitrates (e.g. mono
methyl ammonium nitrate or ethanol amine nitrate), hexamine and
urea.
[0108] Water-immiscible fuels which can be used with the present
invention can be selected from the group consisting of: include
aliphatic, alicyclic and aromatic compounds and mixtures thereof
which are in the liquid state at the formulation temperature.
Suitable organic fuels may be chosen from fuel oil, diesel oil,
distillate, kerosene, naphtha, waxes, (e.g. microcrystalline wax,
paraffin wax and slack wax) paraffin oils, benzene, toluene,
xylenes, asphaltic materials, polymeric oils such as the low
molecular weight polymers of olefins, vegetable oils, animal oils,
fish oils, and other mineral, hydrocarbon or fatty oils, and
mixtures thereof. Suitable organic fuels are liquid hydrocarbons
generally referred to as petroleum distillates such as gasoline,
kerosene, fuel oils, paraffin oils and vegetable oils or mixture
thereof.
[0109] Typically, the water miscible or water-immiscible fuel of
the watergel composition of the present invention comprises from 5
to 30% w/w and suitably 10 to 25% w/w of the total composition.
Suitably the fuel is included in a concentration of about 5, 7, 8,
10, 12, 15, 20, 25, 30, 35, 40, 45, or 50% w/w. Suitably the fuel
is included in a concentration of between about 5 to 10, 10 to 15,
5 to 20, 15 to 20, 15 to 25, 20 to 25, 25 to 30, 20 to 40, 30 to
35, 35 to 40, 40 to 45, or 45 to 50% w/w.
[0110] In one embodiment, the water-immiscible fuel is included at
7 to 25% w/w of the total composition.
[0111] In one embodiment, the water-miscible fuel is included at 8
to 25% w/w of the total composition.
Fuels for Emulsions
[0112] The explosive compositions of the invention may comprise one
or more fuels.
[0113] HP-based emulsions can be prepared with water-immiscible
fuels.
[0114] The fuel can be any fuel such as diesel fuel. Alternatively,
it can be paraffinic, mineral, olefinic, naphthenic, animal,
vegetable, fish and silicone oils. Other types of fuels are
benzene, toluene, xylenes, asphaltic materials and the likes. The
fuel may be a sustainable fuel. Suitable sustainable fuels for use
in emulsions may include vegetable oil, oils such as corn,
cottonseed, olive, peanut, or fatty acid oils. The composition may
comprise between 15 and 25% w/w sustainable fuel, e.g., between 15
and 20%, or between 20 and 25% w/w. The composition may
alternatively comprise less than 40% w/w sustainable fuel, less
than 30%, less than 25%, or less than 20% w/w sustainable fuel,
e.g., 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40% w/w sustainable
fuel.
[0115] The water-immiscible organic phase component of the
composition of the present invention comprises the continuous "oil"
phase of the water-in-oil emulsion and is the fuel. Suitable
organic fuels include aliphatic, alicyclic and aromatic compounds
and mixtures thereof which are in the liquid state at the
formulation temperature. Suitable organic fuels may be chosen from
fuel oil, diesel oil, distillate, kerosene, naphtha, waxes, (e.g.
microcrystalline wax, paraffin wax, and slack wax) paraffin oils,
benzene, toluene, xylenes, asphaltic materials, polymeric oils such
as the low molecular weight polymers of olefins, vegetable oils,
animal oils, fish oils, and other mineral, hydrocarbon or fatty
oils, and mixtures thereof. Suitable organic fuels are liquid
hydrocarbons generally referred to as petroleum distillates such as
gasoline, kerosene, fuel oils, paraffin oils and vegetable oils or
mixture thereof.
[0116] Typically, the organic fuel or continuous phase of the
HP-based emulsion composition of the present invention comprises
from 2 to 20% w/w and suitably 3 to 20% w/w of the total
composition, e.g. from 7 to 12% w/w of the total composition.
Suitably the organic fuel is included in a concentration of about
2, 4, 6, 8, 10, 12, 14, 16, 18, or 20% w/w. Suitably the organic
fuel is included in a concentration of between about 2 to 4, 4 to
6, 6 to 8, 8 to 10, 10 to 12, 12 to 14, 14 to 16, 16 to 18, or 18
to 20% w/w.
Secondary Fuels for Watergels and Emulsions
[0117] If desired, other optional fuel materials, hereinafter
referred to as secondary fuels, may be incorporated into the
compositions of the present invention.
[0118] Examples of such secondary fuels include finely divided
solids. Examples of secondary fuels include sulphur, aluminium,
gilsonite, comminuted coke or charcoal, carbon black, abietic acid,
glucose or dextrose, starch, nut meal, grain meal, wood pulp, etc.,
and combinations thereof. Examples of secondary fuels also include
recycled plastic waste.
[0119] Typically, the optional secondary fuel component of the
compositions of the present invention comprise from 0 to 20% w/w of
the total composition, e.g. at 0.1 to 12% w/w.
Ratios of Components
[0120] In one embodiment, the explosive composition may comprise a
ratio of HP:one or more other oxidisers in the range between 100:1
to 30:70.
[0121] In one embodiment, the explosive composition may comprise a
ratio of HP (or HP+one or more oxidisers):fuel in the range between
87:13 to 64:36.
[0122] In one embodiment, the explosive composition may comprise a
ratio of HP (or HP+one or more oxidisers):fuel:water in the range
between 60:20:20 to 72:24:4.
Thickeners
[0123] The explosive compositions of the invention may comprise one
or more thickeners. More particularly, the watergel explosive
compositions of the invention may comprise one or more
thickeners.
[0124] Because bubbles of gas and materials enclosing gas have a
relatively low density, they will tend to migrate towards the
surface of the column of explosive if the viscosity of the HP-based
explosive composition is not capable of maintaining the sensitising
material homogeneously dispersed throughout. Migration of the
sensitising material towards the surface is undesirable as it may
render the explosive too insensitive to initiation, and therefore
the explosive composition may not deliver the energy and gases
needed to break and move the rock as required or even worse, the
explosive may undergo a misfire. One way to ameliorate this issue
is to formulate the explosive composition into a watergel. These
types of compositions can be formulated with different levels of
viscosity by using a thickener. Viscosities can be selected to
generally retain the sensitising material in a homogeneously
dispersed state throughout the composition.
[0125] If desired the aqueous solution of the compositions of the
present invention may comprise thickeners which optionally may be
crosslinked. Any conventional thickener may be used with the
present invention. The thickeners, when used in the compositions of
the present invention, are suitably polymeric materials, especially
gum materials typified by the galactomannan gums such as locust
bean gum or xantham gum or guar gum or derivatives thereof such as
hydroxypropyl guar gum. The thickener may be selected from gums
including natural gums, such guar gum, xanthan gum, sodium
alginate, carboxymethylcellullose, methylcellulose and the like.
Other useful, but less preferred, gums are the so-called
biopolymeric gums such as the heteropolysaccharides prepared by the
microbial transformation of carbohydrate material, for example the
treatment of glucose with a plant pathogen of the genus Xanthomonas
typified by Xanthomonas campestris. Other useful thickeners include
synthetic polymeric materials and in particular synthetic polymeric
materials which are derived, at least in part, from the monomer
acrylamide. An example of a synthetic thickener is polyacrylamide.
Inorganic thickeners, such as fumed silica, clays and carbosil, may
also be used, or a combination thereof. Suitably the thickener is
selected from locust bean gum, guar gum, hydroxypropyl guar gum,
sodium alginate and heteropolysaccharides, and combinations
thereof.
[0126] Typically, the thickener component of the compositions of
the present invention comprises from 0 to 5% w/w of the total
composition, e.g. from 0.5 to 5% w/w, e.g. from 0 to 2% w/w of the
total composition, e.g. from 0.1 to 2% by weight of the total
composition.
Crosslinkers
[0127] Crosslinkers can also be used with the present
invention.
[0128] Thickeners in combination with crosslinkers can improve the
water resistance and mechanical strength of the explosive. It is
convenient for this purpose to use conventional crosslinkers such
as zinc chromate or a dichromate either as a separate entity or as
a component of a redox system such as, for example, a mixture of
potassium dichromate and potassium antimony tartrate. Salts of Ca,
Ti, Sb can also be used as crosslinkers. In one embodiment the
crosslinker is selected from salts containing zinc, calcium,
titanium, antimony, chromium, borate and dichromate and
combinations thereof.
[0129] Typically, the crosslinker component of the compositions of
the present invention comprises from 0 to 3% w/w, e.g. from 0 to
0.1% w/w of the total composition, e.g. from 0.1 to 1% w/w of the
total composition, e.g. from 1 to 2% w/w of the total composition,
e.g. from 2 to 3% w/w of the total composition.
Emulsifier/Stabiliser
[0130] The explosive compositions of the invention, when prepared
as emulsion form, may comprise one or more emulsifiers.
[0131] HP-based emulsion compositions are made of a discontinuous
phase of oxidising material that is dispersed in a continuous phase
of an organic fuel in the presence of one or more emulsifiers. The
emulsifier is adapted or chosen to maintain phase separation.
[0132] The emulsifier component of the composition of the present
invention may be chosen from the wide range of emulsifiers known in
the art for the preparation of water-in-oil emulsion explosive
compositions. Examples of such emulsifiers include polyisobutylene
succinic anhydride (PIBSA) reacted with amines; examples of other
emulsifiers are PIB-lactone and its amino derivatives, 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, alkyl-sulfonates,
alkylarylsulfonates, alkylsulfosuccinates, alkylphosphates,
alkenylphosphates, phosphate esters, lecithin, copolymers of
poly(oxyalkylene) glycols and poly(12-hydroxystearic acid), and
mixtures thereof.
[0133] Among the preferred emulsifiers are the 2-alkyl- and
2-alkenyl-4,4'-bis (hydroxymethyl) oxazoline, the fatty acid esters
of sorbitol, lecithin, copolymers of poly(oxyalkylene) glycols and
poly(l2-hydroxystearic acid), and mixtures thereof, and
particularly sorbitan mono-oleate, sorbitan sesquioleate,
2-oleyl-4,4'-bis (hydroxymethyl) oxazoline, mixture of sorbitan
sesquioleate, lecithin and a copolymer of poly(oxyalkylene glycol
and poly (12-hydroxystearic acid), and mixtures thereof.
[0134] Typically, the emulsifier component of the composition of
the present invention comprises up to 5% w/w of the total
composition. Higher proportions of the emulsifier may be used and
may serve as a supplemental fuel for the composition but in general
it is not necessary to add more than 5% w/w of emulsifier to
achieve the desired effect. One of the advantages of the
compositions of the present invention is that stable emulsions can
be formed using relatively low levels of emulsifier and for reasons
of economy it is preferable to keep the amount of emulsifier used
to the minimum required to have the desired effect. A suitable
level of emulsifier is in the range from 0.1 to 2.0% w/w of the
total composition.
Energy Diluents
[0135] The explosive compositions of the invention may optionally
comprise one or more energy diluents.
[0136] In the context of this invention, energy diluting agents are
inert materials that have minimal contribution to the detonation
process as sensitising means, however they can be used to replace
part of the energetic material in the composition and therefore
reduce the energy output of the hydrogen peroxide-based
explosive.
[0137] In some cases these energy-diluting agents may increase,
decrease or not alter the density of the HP-based composition. In
some cases, these energy diluting agents are able to reduce the
density of the HP-based composition without increasing the
sensitivity.
[0138] Examples of these diluents materials are EPS (with particle
size larger than 2 mm in diameter), granulated/shredded rubber
(from tyres), cotton seeds, saw dust, husk, expanded popcorn,
plastic beads, wool meal, bagasse, peanut and oat husks, peanut
shells etc. U.S. Pat. No. 5,409,556 describes some examples of
these energy reducing agents. In one embodiment the energy diluting
agent is selected from granulated/shredded tyres, rubber, expanded
rice, expanded popcorn, expanded wheat, and combinations thereof.
These materials could also be used in combination with sensitising
agents to offer more flexibility (as shown in U.S. Pat. No.
5,470,407) as far as the performance properties of the hydrogen
peroxide-based explosive is concerned. Therefore, another advantage
of the HP-based explosive is that the performance properties of the
explosive can be altered to suit the characteristics of the
blasting site.
[0139] Watergel or water-in-oil HP-based explosive compositions
made according to the present invention include energy-diluting
agents in concentration between 0-800% by volume. As a result, the
use of the additives (sensitising agent and energy-diluting
agents), provides a better control of the density, VOD and energy
delivery in the ground being blasted. Therefore, an additional
advantage of the HP-based explosive is that it could be used in a
range of density between 0.3 g/cm.sup.3 to 1.4 g/cm.sup.3.
Density of the Explosive Compositions
[0140] Suitably the final density is controlled with sensitiser to
around 0.3 to 1.4 g/cm.sup.3. Suitably the density of the
composition is formulated to be around 0.3, 0.4, 0.5, 0.6, 0.7,
0.8, 0.9, 1, 1.1, 1.2, 1.3, or 1.4 g/cm.sup.3. Suitably the final
density of the composition is formulated to be between around 0.3
to 0.4, 0.4 to 0.5, 0.5 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 0.9,
0.9 to 1.0, 1.0 to 1.1, 1.1 to 1.2, 1.2 to 1.3, or 1.3 to 1.4
g/cm.sup.3. In some embodiments the density is controlled to a
predetermined target value by selection of the ratios of the
components of the composition. For example, by balancing the
concentration of a component which reduces the density, such as
hollow microspheres, and one that has a relatively high density,
such as nitrate prills.
pH of the Explosive Compositions
[0141] The pH of the emulsion explosive compositions of the present
invention is not narrowly critical. However, in general the pH is
between 0 and 8 and suitably the pH is between 1 and 6, and may be
controlled by suitable addition of conventional additives, for
example inorganic or organic acids and salts.
Viscosity of the Explosive Compositions
[0142] The viscosity of the explosive compositions (watergel or
emulsion type) will be discussed in terms of apparent viscosity.
Where used herein the term "apparent viscosity" refers to viscosity
measure using a Brookfield RVT viscometer, #7 spindle at 50
r.p.m.
[0143] It is preferred in the process of the present invention that
the explosive composition of the water-in-oil emulsion explosive
particles have an apparent viscosity greater than 10 Pa*s
(Pascal*second) prior to the entrainment of gas bubbles. Apparent
viscosity is more suitably in the range 5 to 50 Pa*s. A more
preferred viscosity range for the entrainment of gas bubbles by
mechanical mixing is from 10 to 35 Pa*s. The range 10 to 25 Pa*s
provides the most efficient entrainment of gas bubbles by
mechanical mixing.
[0144] Suitably the explosive composition of the invention can be
easily pumped.
Oxygen Balance of the Explosive Compositions
[0145] "Oxygen balance" (OB) is a term of the art which is used to
indicate the degree to which an explosive can be oxidised. An OB
close to zero is preferred when formulating mining explosives, such
that no reactant is in excess during the detonation process, and
therefore the expected products are nitrogen, water and carbon
dioxide. If the oxygen balance is far from zero, some part of the
reactant materials will not react and instead, those unreacted
material absorb/sink heat from the detonation reaction, which in
turn will cause the explosive to underperform. For example, some
prior art compositions are unsuitable for combustion, as they lack
fuel (and therefore the OB is too positive) and the composition
cannot burn.
[0146] Suitably the amount of fuels materials in the explosive
composition can be adjusted so the composition has a final oxygen
balance between +10 and -10, e.g. between +5 and -5.
Preparation of Explosive Compositions
[0147] According to a second aspect the present invention provides
a method of preparing an explosive composition according to the
first aspect, the method comprising combining hydrogen peroxide and
one or more other oxidisers.
[0148] The explosive compositions of the present invention may be
prepared by a number of methods. Possible variations of this
general procedure will be evident to those skilled in the art of
the preparation of emulsion explosive compositions.
[0149] The method may comprise the step of formulating said
composition as a watergel or an emulsion.
[0150] The method may further comprise the step of adding a
water-immiscible or water-miscible fuel.
[0151] The method may further comprise the step of adding a
thickener or an emulsifier.
[0152] The method may further comprise the step of adding a
secondary fuel.
[0153] The method may further comprise the step of adding an energy
diluting agent.
[0154] The method may further include a sensitisation step.
[0155] The method may further comprise the step of adding a
crosslinker.
[0156] In one suitable method of manufacture the explosive watergel
type compositions may be prepared by: [0157] making an oxidiser
phase by combining hydrogen peroxide with one or more other
oxidisers and one or more water soluble fuels, and then [0158]
making a fuel phase by adding one or more water-miscible fuels
(e.g. glycerol) and one or more thickeners (e.g. gum such as guar
gum) and mixing (e.g. stirring) to suspend the thickener; [0159]
mixing both the fuel phase and the oxidiser phase; [0160]
optionally one or more other oxidisers in a solid form (which are
the same as or different from the one or more other oxidisers of
the oxidiser phase) can be added, as a powder or prills, and
mixing; [0161] adding and mixing secondary fuels; [0162] adding and
mixing energy diluting agents; [0163] sensitising agents are mixed
into said composition in an amount capable to sensitise said
composition (e.g. after 2 to 5 minutes of mixing, a gassing agent
is added); [0164] crosslinking agents are mixed to convert the
composition into a gel.
[0165] In one suitable method of manufacture the explosive emulsion
type compositions may be prepared by: [0166] making an oxidiser
phase by dissolving one or more oxidisers with hydrogen peroxide;
and then [0167] making a fuel phase by adding one or more water
insoluble fuels (e.g. diesel) and one or more emulsifiers (e.g.
PIBSA-based or SMO) and mixing (e.g. stirring) to suspend the
thickener; [0168] adding the fuel phase to the oxidiser phase
whilst mixing; [0169] optionally one or more other oxidisers in a
solid form (which are the same as or different from the one or more
other oxidisers of the oxidiser phase) can be added, as a powder or
prills, and mixing; and [0170] sensitising agents are mixed into
said composition in an amount capable to sensitise said
emulsion.
Use of the Compositions
[0171] It will be appreciated that the composition of the invention
can be used for many purposes, but in particular to break and move
ground in mining operations.
[0172] Thus according to a third aspect the present invention
provides use of an explosive composition according to the first
aspect to break and move ground, e.g. in mining operations.
[0173] Suitably the explosive composition is introduced (e.g. by
pumping) into a blasthole that already has a detonator placed
therein. Detonation of blastholes in a mining operation is well
known to the person skilled in the art.
Preferred Embodiment of the Invention
[0174] Numerous embodiments are described in this patent
application, and are presented for illustrative purposes only. The
described embodiments are not intended to be limiting in any sense.
The invention is widely applicable to numerous embodiments, as is
readily apparent from the disclosure herein.
[0175] In one embodiment, the present invention comprises or
consists essentially of hydrogen peroxide, one or more other
oxidisers, wherein at least some of at least one of the one or more
other oxidisers may be present in the composition in solid form
(e.g., powder, prills) a fuel, a thickener, a sensitiser, a
crosslinker, a secondary fuel and an energy diluting agent. In
other embodiments the present invention comprises or consists
essentially of hydrogen peroxide, one or more other oxidisers,
wherein at least some of at least one of the one or more other
oxidisers is present in the composition in solid form (e.g.,
powder, prills), a fuel, a surfactant/emulsifier, a sensitiser, a
secondary fuel and an energy diluting agent. In such embodiments,
the final oxygen balance of the mixture is preferably between -5 to
+5.
[0176] The present invention relates to a
peroxide-nitrate/fuel-based explosive composition that is suitably
prepared as watergel or water-in-oil emulsion, which may or may not
contain solid oxidiser and is sensitised. Typical components for
each type of explosive technology are listed in Table 1.
TABLE-US-00001 TABLE 1 Typical components of the present invention
for each type of explosive technology. Explosive technology
Component Watergel Water-in-oil emulsion Oxidiser(s) hydrogen
peroxide and one or hydrogen peroxide and one or more other
oxidisers selected more other oxidisers selected from the group
consisting of from the group consisting of nitrate salts and/or
perchlorate nitrate salts and/or perchlorate salts and/or
sodium/potassium salts and/or sodium/potassium peroxide and/or
nitric acid. peroxide and/or nitric acid. Optionally water miscible
fuels Optionally water miscible fuels can be added to this phase
can be added to this phase (amine nitrates, urea, etc) (amine
nitrates, urea, etc) Sensitiser gas bubbles (chemically gas bubbles
(chemically generated or injected bubbles) generated or injected
bubbles) and/or gas entrapped and/or gas entrapped compressible
materials compressible materials Fuel Water miscible fuels, water
Water miscible fuels, water soluble fuels or water-insoluble fuels
immiscible fuels, water soluble fuels or water-insoluble fuels
Stabilisers thickeners emulsifiers Additives crosslinkers,
catalysts for catalysts for gassing, pH adjusters gassing, pH
adjusters Energy Granulated/shredded rubber, Granulated/shredded
rubber, diluents expanded popcorn, expanded expanded popcorn,
expanded (optional) rice, plastic beads, EPS >5 mm rice, plastic
beads, EPS >5 mm
Error! Reference source not found. lists the components of
explosive systems discussed herein and provides typical ranges for
each.
TABLE-US-00002 TABLE 2 Components for explosive systems discussed
herein with typical ranges for each Component (in % by weight of
total composition except where Explosive technology indicated
otherwise) Watergel Emulsion HP From about 2 to 25 From about 2 to
25 One or more other From greater From greater oxidisers than 0 to
90 than 0 to 90 Sensitiser (% by volume) From 1 to 800* From 1 to
800* Fuels From 8 to 25 From 7 to 25 Secondary fuels From 0.1 to 11
From 0.1 to 11 Water From 5 to 20 From 5 to 20 Thickeners From 0.5
to 5 N/A Emulsifiers N/A From 0.5 to 5 Additives 0.1 to 5 0.1 to 5
Energy diluting agents (% From 1 to 300** From 1 to 300** by
volume) Oxygen Balance From 5 to -5 From 5 to -5 Final densities
(g/cm.sup.3) 0.30 to 1.40 0.30 to 1.40 NOTE: it will be appreciated
that the volume can be increased by 8x(*), and 3x(**),
respectively.
Examples
[0177] The present invention can be used for a variety of forms of
explosives provided of course that the principles of the invention
as described herein are observed. The invention is further
illustrated with reference to the following examples detailed in
Table 3.
TABLE-US-00003 TABLE 3 Examples of the invention Composition
(%-w/w) 1 2 3 4 HP-CAN/ HP-CAN/Fuel- HP- HP-SN/Fuel- Fuel- based
gel blend + SN/Fuel- based gel blend + Chemical based gel CAN
prills based gel SN prills HP (50% 39.50* 10.8** 55.3*** 32.34****
w/w) CAN 39.50 65.8 SN 23.7 43.86 Glycerol 19.32 22.7 18.9 21.42
Xanthan 1.68 0.7 2.1 2.38 gum *39.5 .times. (50/100)% = 19.75 w/w %
HP **10.8 .times. (50/100)% = 5.4 w/w % HP ***55.3 .times.
(50/100)% = 27.65 w/w % HP ****32.34 .times. (50/100)% = 16.17 w/w
% HP
Detonation Testing
[0178] Selected compositions were tested to determine detonation.
PVC pipes 50 mm in diameter by 600 mm in length and sealed on one
end were used for gels. PVC pipes 102 mm in diameter by 600 mm in
length, sealed on one end were used for composition made of gel and
prills.
[0179] VOD was measured using a Time Domain Reflectometry
(TRD)-based VOD instrument.
[0180] The examples 1-4 above in Table 3 (corresponding to FIGS.
1-4, respectively) show that combination of HP and nitrates are
able to be detonated over a range of densities and providing a
range of velocities of detonation.
[0181] From the Figures, it can be seen that explosives
compositions, such as HP-CAN/fuel based gel blend and CAN prills,
as described herein are able to be detonated with low
concentrations of HP, e.g., 5.4% w/w, or lower. The examples also
contain a relatively large amount of nitrates in the composition.
There is no evidence in the previous art that high levels of CAN or
SN can be used for water-based explosive compositions at different
densities.
[0182] Although the invention has been described with reference to
specific examples, it will be appreciated by those skilled in the
art that the invention may be embodied in many other forms. In
particular features of any one of the various described examples
may be provided in any combination in any of the other described
examples.
[0183] The skilled addressee will understand that the invention
comprises the embodiments and features disclosed herein as well as
all combinations and/or permutations of the disclosed embodiments
and features.
* * * * *