U.S. patent application number 14/383866 was filed with the patent office on 2015-02-05 for modified blasting agent.
The applicant listed for this patent is DYNO NOBEL ASIA PACIFIC PTY LIMITED. Invention is credited to Jeff Gore, Nathan Paris.
Application Number | 20150033969 14/383866 |
Document ID | / |
Family ID | 49115792 |
Filed Date | 2015-02-05 |
United States Patent
Application |
20150033969 |
Kind Code |
A1 |
Gore; Jeff ; et al. |
February 5, 2015 |
MODIFIED BLASTING AGENT
Abstract
The present invention relates generally to an explosive
composition comprising an aqueous emulsion of: an oxidizer
component, a hydrocarbon fuel component containing emulsifier, and
a bulking agent being a fuel-type waste material in a solid
particulate form substantially lacking rough surfaces and sharp
edges. Preferably the composition is of an ammonium nitrate based
emulsion and a pelletised bulking agent. It also involves a method
of providing an explosive composition to a blast site using a
conventional mobile processing unit (MPU), being a truck having
separate compartments adapted for holding fuel oil, dry ammonium
nitrate prill, and ammonium nitrate based emulsion, where a
compartment instead holds particulate waste material. It also
concerns a method of blasting soft and wet ground, which comprises
injecting into one or more blast holes in the soft and wet ground a
sufficient quantity of the composition, and then setting off the
composition.
Inventors: |
Gore; Jeff; (Mt. Thorley,
AU) ; Paris; Nathan; (Mt. Thorley, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DYNO NOBEL ASIA PACIFIC PTY LIMITED |
Southbank, Victoria |
|
AU |
|
|
Family ID: |
49115792 |
Appl. No.: |
14/383866 |
Filed: |
March 8, 2013 |
PCT Filed: |
March 8, 2013 |
PCT NO: |
PCT/AU2013/000219 |
371 Date: |
September 8, 2014 |
Current U.S.
Class: |
102/313 ; 149/2;
149/46; 149/61 |
Current CPC
Class: |
C06B 45/00 20130101;
C06B 31/285 20130101; C06B 21/0008 20130101; C06B 31/02 20130101;
F42D 3/00 20130101; C06B 47/145 20130101; F42D 1/00 20130101; C06B
31/28 20130101; C06B 43/00 20130101 |
Class at
Publication: |
102/313 ; 149/61;
149/46; 149/2 |
International
Class: |
F42D 1/00 20060101
F42D001/00; C06B 43/00 20060101 C06B043/00; C06B 31/28 20060101
C06B031/28; C06B 45/00 20060101 C06B045/00; F42D 3/00 20060101
F42D003/00; C06B 31/02 20060101 C06B031/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2012 |
AU |
2012900943 |
Claims
1. An explosive composition comprising an aqueous emulsion of an
oxidizer component, a hydrocarbon fuel component containing
emulsifier, and fuel-type waste material in a solid particulate
form lacking rough surfaces and sharp edges sufficiently so as to
not promote crystallisation of the emulsion.
2. The composition of claim 1, wherein the presence of the waste
material alone does not provide sensitisation to the emulsion to
permit an explosion; an explosion being permitted by the later
addition of a sensitisation component to the composition.
3. The composition of claim 2, wherein the sensitisation component
is a density reducing agent.
4. The composition of claim 1, wherein the oxidizing agent is
selected from one or more of ammonium nitrate, sodium nitrate, or
calcium nitrate.
5. The composition of claim 4, wherein the oxidizing agent is
ammonium nitrate.
6. The composition of claim 3, where the density reducing agent is
a salt of an alkali metal nitrite and an acid, which generate
nitrogen gas when combined.
7. The composition of claim 1, wherein the composition of the fuel
type waste material is selected from any one or more of: plastics
material, rubber, paper, cardboard, wax material, and commingled
plastic waste material.
8. The composition of claim 6, wherein the density of the
composition is reduced to between 0.80 and 1.15 g/cm.sup.3 by the
addition of the density reducing agent.
9. The composition of claim 1, wherein the particulate waste
material is in the form of pellets substantially lacking rough
surfaces and sharp edges.
10. The composition of claim 1, wherein the particulate waste
material has an average particle size of about 2 to 3 mm.
11. The composition of claim 1, wherein the waste material
comprises from 1% to 50% by weight of the total composition.
12. The composition of claim 11, wherein the waste material
comprises from 10 to 40% by weight of the total composition.
13. The composition of claim 1, wherein the fuel-type waste
material in a solid particulate form has a Rod Rating test (as
described herein) value of 6 or higher.
14. A method of providing an explosive composition to a blast site
having one or more blastholes for receiving the composition, by
means of a conventional mobile processing unit (MPU), said unit
comprising a truck having separate compartments adapted for holding
(a) fuel oil, (b) dry ammonium nitrate prill, and (c) ammonium
nitrate based emulsion, and said unit having means for mixing two
or more of the components from compartments (a), (b) and (c)
together and injecting the resulting mixture in a blasthole,
characterised in that compartment (b) instead holds particulate
waste material, and a density reducing agent is added to the
mixture from compartments (a), (b) and (c) just prior to it being
injected into a blast hole by an auger on the MPU, and wherein the
composition is as defined in claim 1.
15. The method of claim 14, wherein the mixture is injected into
the blasthole by means of an auger.
16. A method of blasting soft and wet ground, which comprises
injecting into one or more blast holes in the soft and wet ground a
sufficient quantity of the composition according to claim 1, and
then setting off the composition.
17. The method of claim 16, wherein the composition is injected
into the blast holes by means of a conventional mobile processing
unit, said unit comprising a truck having separate compartments
adapted for holding (a) fuel oil, (b) dry ammonium nitrate prill,
and (c) ammonium nitrate based emulsion, and said unit having means
for mixing two or more of the components from compartments (a), (b)
and (c) together and injecting the resulting mixture in a
blasthole, characterised in that compartment (a) instead holds
particulate waste material, and a density reducing agent is added
to the mixture from compartments (a), (b) and (c) just prior to it
being injected into a blast hole by an auger of the MPU.
18. The method of claim 17, wherein the mixture is injected into
the blasthole by means of an auger.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to blasting agents
and explosive compositions and to methods of making, using and the
delivery of such agents. More particularly, the present invention
concerns a multi-component explosive formulation which utilises
waste materials which otherwise would have been destined for
landfill or high temperature incineration. In particularly, though
not exclusively, the present invention relates to the manufacture,
use and delivery of blasting agents comprising various forms of
ammonium nitrate based emulsion explosives, which have been
modified by the incorporation of waste material as a component of
the explosive.
BACKGROUND ART
[0002] Once a material has served a purpose or is a by-product of
an industrial process, it becomes a waste material. There are
generally a number of different ways in which it can be managed for
its safe and environmentally sustainable disposal. One way is
separation, recycling and eventual re-use. Another way is to
manufacture the material from easily biodegradable material; so
that when the material is finally disposed of in landfill, it has a
shorter lifespan there compared to non-biodegradable materials.
[0003] However, there are some materials which cannot be either
recycled or made of biodegradable materials. In this situation, the
material is managed by either incinerating it or by burying in
landfill where it will degrade only slowly. The disposing of waste
material in land fill then constrains the use of this land, for
example with some waste material such as plastics taking up to 400
years to decay. The burning of waste material such as plastics
often requires high temperatures, so that it is difficult and
costly to do. But this process may also release harmful pollutants,
often in industrial areas where pollution may already be an
issue.
[0004] One way to address these issues is to incorporate such
difficult to recycle or degrade waste material into an explosive
composition. The extreme conditions and high temperatures generated
when such an explosive composition detonates achieves the purpose
of disposing of the material, in an analogous manner to high
temperature incineration, but achieving a useful result, and
potentially at lower cost.
[0005] This approach has previously shown to be achievable for the
addition of particulate rubber with solid ammonium nitrate as
disclosed in U.S. Pat. No. 5,505,800 (Harries et al). This citation
is primarily directed to creating "low shock energy explosives"
(LSEE). The rubber can be sourced from shredding used tyres.
However, the rubber particulates produced have rough edges, which
it has since been found can lead to crystallisation in the
explosive mixture when the rubber is mixed with ammonium nitrate
based emulsions. Crystallisation can prevent the mixture detonating
or it will give a poor result.
[0006] Another attempt to use waste material in this manner,
involves mixing of energetic waste with different explosive
compositions such as AN, ANFO, water gels and emulsions, as
disclosed in U.S. Pat. No. 5,536,897 (Clark et al). This citation
generally concerns using waste material contaminated by rocketry
fuel. The waste material is then shredded. The presence of residual
rocket fuel in the waste ensures that the waste material
contributes to the blasting performance of the final explosive.
However, the absence of such fuel material in the waste material
can result in the explosive composition not detonating.
[0007] The presence of shredded material in an emulsion blend may
create material with rough edges and these edges can lead to
crystallisation of a product. The crystallisation of a product can
result in poor performance of the explosive with reduced water
resistance and increased risk of post blast fumes.
[0008] Accordingly, it would be useful to provide a solution that
avoids or ameliorates any of the disadvantages present in the prior
art, or which provides another alternative to prior art
approaches.
SUMMARY OF THE INVENTION
[0009] According to one aspect of the invention there is provided
an explosive composition comprising an aqueous emulsion of: an
oxidizer component, a hydrocarbon fuel component containing
emulsifier, and fuel-type waste material, as a bulking agent, being
in a solid particulate form that substantially lacks rough surfaces
and sharp edges sufficiently so as to not promote crystallisation
of the emulsion.
[0010] Another aspect of the invention involves a method of
providing an explosive composition to a blast site having one or
more blastholes for receiving the composition, by means of a
conventional mobile processing unit (MPU), said unit comprising a
truck having separate compartments adapted for holding (a)
hydrocarbon fuel component such as fuel oil, (b) the dry oxidiser
component such as dry ammonium nitrate prill, and (c) the wet
oxidiser component such as ammonium nitrate based emulsion, and the
unit having means for mixing two or more of the components from
compartments (a), (b) and (c) together and injecting the resulting
mixture in a blasthole, characterised in that compartment (b)
instead holds the bulking agent in the form of particulate waste
material, and where a density reducing agent is added to the
mixture from compartments (a), (b) and (c) just prior to it being
injected into a blast hole, preferably by an auger on the MPU, and
wherein the composition is in accordance with the invention.
[0011] Yet another aspect of the invention concerns a method of
blasting soft and wet ground, which comprises injecting into one or
more blast holes in the soft and wet ground a sufficient quantity
of the composition according to the invention, and then setting off
the composition.
[0012] The oxidizer component of the emulsion is generally an
aqueous solution or melt containing an oxygen-releasing salt.
Preferably the oxygen-releasing salt is selected from one or more
of ammonium nitrate, sodium nitrate, calcium nitrate, or ammonium
perchlorate, and most preferably it is ammonium nitrate.
BRIEF DESCRIPTION OF DRAWINGS
[0013] Preferred embodiments of the invention will now be
described, by way of example only, with reference to the
accompanying drawings in which:
[0014] FIG. 1 is a schematic of a truck able to be used for
delivering blasting explosives, according to the present
invention:
[0015] FIGS. 2a and 2b show photographs (not to scale) of two
products (A & B) of waste material pellet components that may
be used in the invention; and
[0016] FIG. 2c shows another photograph (not to scale) of product B
(FIG. 2b) waste pellets showing their smooth appearance that may be
used in the invention,
[0017] FIG. 2d shows a photograph (not to scale) of another product
of waste pellets, for use in the invention, and
[0018] FIGS. 3a and 3b, show photographs (not to scale) of
comparison waste products that do not form part of the invention,
showing the roughness and jagged nature of their surfaces, and the
sharp edges and corners present.
DESCRIPTION OF EMBODIMENTS
[0019] According to the present invention, there is provided an
explosive composition, preferably comprising an ammonium nitrate
(AN) type based emulsion and a waste material as a bulking agent.
The waste material is in solid particulate form.
[0020] The waste material is fuel-type waste material, generally
being waste that can combust at high temperatures in the presence
of an oxidiser. Generally this waste may be carboniferous
materials, such as waste plastics, rubber, paper, waxes, and the
like. Some suitable sources of waste material includes nylon
pellets, cardboard, polyethylene, wax, and commingled plastic
waste. Preferably the solid particulate form is in the form of
pellets or the waste material. Some other suitable sources of waste
include readily oxidisable metal, such as aluminium.
[0021] Commingled plastics wastes, including a substantial amount
of polyethylene and similar plastics, sourced from plastics from
domestic waste collections may be utilised. These are generally
finely chopped and ground to a powder, and the powder melted or
compressed together, and then extruded to form smooth surfaced
waste plastic pellets, with rounded corners and edges. Other
materials such as commingled paper and cardboard wastes optionally
with a waxy wastes, may be shredded and compressed together to form
smooth pellets with rounded edges.
[0022] The waste material is in a granular or particulate form,
preferably having an average particle size of for 0.5 to 10 mm, and
more preferable from around 1 to 4 mm, and most preferably around 2
to 3 mm in size. These pellets may be spherical, cylindrical, cube
shaped, as square or rectangular blocks, or irregular in shape,
with generally smooth surfaces and rounded edges.
[0023] It is also a preferred feature that the granular waste
material in particulate form should be of a similar size to the
particulate solid AN prill that is in the blasting composition. AN
prill is typically between 1 to 4 mm in size, and so using
particulate waste material that has a similar size distribution is
advantageous. The loading equipment is able to function effectively
with the prill particles, and so by using waste particles of a
similar size, the equipment will also function efficiently with
that.
[0024] It is also advantageous that the waste material have a
density that is not too low, as very low density additives, such as
microballoons or styrene beads are known to be added as sensitising
agents. Preferably the waste particles can have a density of around
0.2 to 1.0 g/cm.sup.3, and more preferably around 0.4 to 0.7
g/cm.sup.3. Ideally the waste material particles themselves should
not substantially affect the sensitisation of the blasting
emulsion.
[0025] As described below in more detail, these waste material
particles should have relatively smooth surfaces and a minimum of
sharp edges, sufficiently so, that they do not destabilise the
emulsion, or do not promote the crystallisation of the emulsion.
The stability of the emulsion can be measured using the Rod Rating
test, as described below, and preferably, waste type pellets that
provide a Rod Rating test result of 6 or higher when mixed with an
AN emulsion are ideal for the invention.
[0026] FIGS. 2a, 2b, 2c, and 2d, show photographs (not to scale) of
samples of some pellets that may be used in the present invention.
The sample in FIG. 2a is sourced from paper and cardboard. The
samples in FIGS. 2b, 2c and 2d, show samples sourced from waste
plastics. In these samples, waste high density polyethylene is the
major constituent. These samples show smooth outer surfaces and
rounded edges and corners. In contrast the samples shown in the
photographs for FIGS. 3a, and 3b show prior art bulking agents,
which have rough surfaces, with sharp edges and corners, as well as
small sharp whiskers, that destroy the emulsion, if these were to
be used in an analogous blasting composition.
[0027] The waste material has the advantage of being unwanted, and
also will often be a cost effective material to use as a
consequence. Its use also permits the waste to be removed from the
environment, by being incinerated in the explosion. Alternatively,
fresh plastics material may be used as the source of some (or all),
of the fuel type waste material. The term "waste material" is to
interpreted broadly in this invention, and while it is preferred to
use plastics waste, recycled from other applications, the use of
fresh material is also permitted, if it fulfils the same purposes.
It is intended that recycled waste would be the primary source, due
to its low cost, but at times, there may be shortages of such
material, or temporary price rises, or unexpected increase in
demand for the blasting composition, and in these circumstances
some fresh material may be substituted for the waste.
[0028] In addition, other difficult or expensive to dispose of
materials may be included in the waste, especially those that may
be expensive to dispose of apart from in a high temperature
incinerator, which may be expensive to do. Waste disposal companies
may pay to have these components added to the explosive by
incorporation in the waste particulate material, thereby improving
the economic benefit of producing the blasting agent of the
invention. Any such materials should be included if they will not
damage the environment if small quantities do not get completely
incinerated. This option is also advantageous if the blasting is of
coal, for example that is to be burnt to produce electricity, so
that any such materials will then be burnt in any case. Such
materials are ideally carboniferous waste products that would
otherwise be incinerated, but which can instead be included in the
blasting composition. Colourants, such as waste organic dyes and
similar materials may be examples of such materials.
[0029] The oxidizer component used in the invention is preferably
an ammonium nitrate (AN) based emulsion. However, other oxidizers
may be used in place of, or in addition to, ammonium nitrate. These
may include alkaline earth nitrates such as calcium nitrate, or
alkali metal nitrates such as sodium nitrate, and urea. Some other
example may include alkaline earth or alkali metal perchlorates
such as for instance, ammonium perchlorate, although these are not
often used due to environmental concerns. Most preferably, an
aqueous solution of ammonium nitrate is used alone as the
oxidizer.
[0030] The hydrocarbon fuel component of the invention is generally
fuel oil, such as mineral or diesel oil, as used with conventional
ANFO blasting explosives in the quarrying, mining, and civil
construction industries.
[0031] The hydrocarbon fuel component contains emulsifier that is a
generally any of the emulsifiers used with AN emulsion blasting
explosives. A single emulsifier or a combination of emulsifiers may
be used. Some preferred emulsifiers may be selected from the group
of emulsifiers that result from condensation reactions between
PIBSA and amines or alkanolamines. Another example of a suitable
emulsifying agent is sorbitan mono-oleate, or the like. A preferred
emulsifier may be selected from of at least one derivative of
poly(isobutylene) succinic anhydride or poly(isobutylene) succinic
acid emulsifier with diethylethanolamine or other alkanolamines.
The emulsifying agent preferably constitutes between 0.3 to 3.5% by
weight of the total composition and most preferably from 0.5 to
1.5% by weight.
[0032] Most preferably the waste material used is such that, when
mixed with the other AN emulsion components, it does not sensitise
the emulsion so as to permit an explosion. This operates as a
safety feature to prevent accidental triggering of an uncontrolled
explosion.
[0033] Ideally, the mixture of the AN emulsion and the waste
material is then sensitised, preferably at the time it is injected
into a blast hole, by the addition of a separate sensitisation
component. This sensitisation component may be a density reducing
agent. One preferred example of a suitable such sensitisation agent
is an alkali metal nitrite, and an acid, which when mixed together
produce nitrogen gas, thereby reducing the density of the explosive
blasting emulsion. Ideally, the density of the emulsion is reduced
to less than 1.15 g/cm.sup.3 and preferably between 0.80 g/cm.sup.3
and 1.15 g/cm.sup.3, by selecting a suitable quantity of
sensitisation agent to mix with the emulsion.
[0034] The particulate waste material is in solid particulate form,
which has particles that substantially lack rough surfaces and
sharp edges. This feature will therefore not promote the emulsion
crystallising. The absence of sharp/rough edges does not provide a
means for disruption, and therefore crystallisation, of the
emulsion droplets.
[0035] An amount of simple testing may be carried out to test if
any potentially suitable waste particulate will work in the
invention. Ideally any waste product may be utilised if it is able
to be oxidised in the resulting explosion, and will not destabilise
the emulsion. Preferably also, the waste product should not provide
sensitisation to the product, to allow the blasting agent to be
sensitised separately, at the time it is pumped into the shot
holes, by gassing the emulsion to reduce its density, for
example.
[0036] Preferably, the waste particulates are in the form of
pellets, ideally pellets having rounded and smooth surfaces and
edges. These pellets may have an average particle size that is
similar to that of AN prill, for example ideally being around 2 to
3 mm in diameter.
[0037] Preferably, the waste matter comprises from 1% to 50% by
weight of the total composition, when all the components are
combined, prior to triggering an explosion. More preferably, the
waste material comprises from 10% to 40% of the composition.
[0038] The blasting agents of the invention are particularly useful
in wet soft ground. Generally an explosive composition has good
water resistance if there is 60% or greater emulsion content in the
explosive. Therefore, the explosive composition of this invention
would generally be good for use in wet ground.
[0039] Soft ground requires less energy for the ground to move. The
calculated energy of ANFO is 3.7 MJ/kg compared to one of the
formulations for the invention being 2.0 MJ/kg. The relative weight
strength of that formulation is 0.54 compared to ANFO of 1.0 and
the relative bulk strength at a density of 1.05 g/cc is 0.69
compared to 1.0 for ANFO. Therefore the energy of this product is
less than ANFO or even emulsion-ANFO blends and so is better suited
for soft ground.
[0040] Preferably the compositions of the invention are delivered
to the site where the blasting is to take place using a
conventional mobile processing unit (MPU) truck, which is carrying
the components in the sections normally used to hold the components
of traditional AN emulsion blasting agents. The waste material is
stored in and sourced from the storage container usually reserved
for the ammonium nitrate used in dry addition, ie section (b). The
explosive composition is delivered from an auger of the MPU. The
density reducing agent is ideally added to the explosive
composition before the explosive composition exits from the auger
into the blast holes.
EXAMPLES
[0041] Laboratory batches of the ammonium nitrate based emulsion
were manufactured as outlined below. Table 1 lists the ingredients
and weights used to manufacture the emulsion. Other formulations
also fall within the present invention.
[0042] General Emulsion Manufacture Procedure
[0043] The ingredients of the oxidizer phase were heated to 75 C to
form an aqueous solution. Separately, the ingredients of the fuel
phase were mixed while heating to 65 C. The hot oxidizer phase was
then poured into the fuel phase slowly, with agitation provided by
a "Lightnin` Labmaster.TM." mixer fitted with a 65 mm "Jiffy.TM."
stirring blade rotating initially at 600 rpm for 30 seconds. The
crude emulsion was refined by stirring at 1000 rpm for 30 seconds,
1400 rpm for 30 seconds and 1700 rpm until the stated viscosity was
achieved. The quantity of product prepared in each sample was 2.0
kg.
[0044] This represents a standard formulation that was used as the
emulsion source for the different blends. The formulation is shown
in Table 1 below.
[0045] The emulsifier was selected from the group of emulsifiers
that result from condensation reactions between PIBSA and amines or
alkanolamines. The mineral oil used was predominantly paraffinic
with some aromatic and naphthentic constituent compounds. The
emulsion was formed with a viscosity about 25,000 cP.
TABLE-US-00001 TABLE 1 Table 1 - Standard Emulsion Formulation
Oxidiser Component 94% Ammonium Nitrate 75% Water 25% Hydrocarbon
Fuel Component 6% Emulsifier 15% Mineral Oil/Fuel Oil 85%
[0046] The waste material was supplied by "Australian Composite
Technology" company ("Plasmar") of Victoria Australia. In these
examples, the material was supplied in two versions, either in a
shredded form or as a pellet. The material that was shredded
generally had sharp edges and this resulted in the destabilisation
of the ammonium nitrate based emulsion due to the sharp edges
interacting with the droplets in the emulsion and causing
crystallisation. The other form, pelletised material, generally did
not destabilise the emulsion, although this was also dependent on
the material used.
[0047] Four materials were tested, these included (1) nylon
pellets, (2) cardboard pellets, (3) pellets which consist of a
mixture of cardboard, polyethylene and wax, (called "Product A")
and (4) pellets which consist of comingled plastics (called
"Product B". A photograph (not to scale) of Product A is shown in
the drawings as FIG. 2a, and of Product b as FIG. 2b, where a ruler
is shown, indicating that the particles are about 3 mm in
diameter.
[0048] It should be noted that cardboard does contain somewhat
rough fibres and this in theory can lead to destabilisation of an
emulsion. However, if the cardboard is pelletised, this reduces the
surface area sufficiently that some ammonium nitrate based
emulsions can be used with it. In particular, formulations whereby
the fuel phase only consists of emulsifiers and mineral oil with no
diesel fuel oil present appear to be particularly suitable in this
combination.
[0049] To retain the water resistance ability of the emulsion, at
least 50% emulsion should be retained in the blend, although
ideally it should be 60% or greater. Conversely the level of waste
material can be between 1 to 50%, although preferably it will be
between 10 and 40%.
[0050] A dry mix can be added to the ammonium nitrate based
emulsion. The dry mix can consist of ammonium nitrate or a mixture
of ammonium nitrate and diesel oil (ANFO). The dry addition, if
used, comprises from 0 to 40%, by weight of the total composition.
The blasting profile may be modified by the addition of ANFO, for
example, by providing more heave to the blasting profile.
[0051] The waste materials preferably are pelletised so as to
provide a compact structure devoid of any significant cavities in
the material. As a result, the waste material provides no
sensitisation and does not participate in the explosive reaction.
Furthermore, the size of the material, approximately 3 mm in size,
means that there is decoupling between the oxidiser and fuel. This
was observed to be the case when the Product B pellets were mixed
with ammonium nitrate in a ratio of 93% by weight ammonium nitrate
and 7% by weight pellets. The product was fired in 223 mm diameter
PVC pipes and the composition failed to detonate. Only when 1.5% of
the ammonium nitrate was replaced with diesel fuel did the material
detonate at low order at 1,700 m/s.
[0052] Sensitisation may be provided by the addition of a density
reducing agent. Such density reducing agents can be any of the many
described in the art, such as glass or plastic microballoons,
occluded air or by being chemically gassed. It is preferred that
the material is chemically gassed using alkali metal nitrites salts
such as sodium nitrite or potassium nitrite. Typically a 20 to 30%
solution of sodium nitrite is added to an acidified ammonium
nitrate based emulsion. The nitrite ions are protonated and then
react with the ammonium ions to generate nitrogen gas. Generation
of the gas is normally completed within 20 to 60 minutes. The
amount of the sodium nitrite solution used determines the final
density of the explosive composition. Density of the final
explosive composition should ideally be under 1.15 gm/cm.sup.3 and
most preferably between 0.8 to 1.15 g/cc to ensure the composition
will detonate.
[0053] Below various examples of the invention are shown. These are
examples only and do not in any way limit the invention.
Comparative Example 1
Not this Invention
[0054] In the first example, not part of this invention, TITAN.TM.
2000 emulsion 70% by weight was mixed with ANFO 30% by weight. The
mixture was acidified with a 50% acetic acid solution and then a
25% by weight sodium nitrite solution was added to the explosive
composition at 0.30% weight of the total explosive composition.
This addition reduced the explosive composition from 1.32 g/cc to
1.10 g/cc. The explosive composition was loaded into 102 mm
diameter PVC pipes and detonated using a 400 g Pentolite booster
fitted with a #12 strength detonator. A VOD of 4,000 m/s was
recorded. The stability of the mixture was determined to have a Rod
Rating of 6 after 28 days.
Comparative Example 2
Not this Invention
[0055] In the second example, not part of this invention, TITAN.TM.
2000 emulsion 80% by weight was mixed with Product B 20% by weight
and no sensitisation was added. The mixture had a density of 1.17
g/cc and was loaded into 152 mm diameter PVC pipes and detonated.
The product failed to detonate when initiated with a 400 g
Pentolite booster fitted with a #12 strength detonator. These
results indicate that the Product B does not provide sensitisation
to the emulsion.
[0056] The following examples show that sensitisation is
required.
Example 3
[0057] In the third example, TITAN.TM. 7000 emulsion 80% by weight
was mixed with Product A at 20% by weight. The mixture was
acidified with a 50% by weight acetic acid solution and then a 25%
by weight sodium nitrite solution was added to the explosive
composition at 0.3% by weight of the total explosive composition.
This addition reduced the explosive composition from 1.27 g/cc to
1.10 g/cc. The explosive composition was loaded into 152 mm
diameter PVC pipes and detonated using a 400 g Pentolite booster
fitted with a #12 strength detonator. A VOD of 3,800 m/s was
recorded. The stability of the mixture was determined to have a Rod
Rating of 6 after 20 days, and the blend breaks down after 28
days.
Example 4
[0058] In a fourth example, TITAN.TM. 2000 emulsion 80% by weight
was mixed with Product B 20% by weight. The mixture was acidified
with a 50% acetic acid solution and then a 25% by weight sodium
nitrite solution was added to the explosive composition at 0.2%
weight of the total explosive composition. This addition reduced
the explosive composition from 1.17 g/cc to 1.02 g/cc. The
explosive composition was loaded into 152 mm diameter PVC pipes and
detonated using a 400 g Pentolite booster fitted with a #12
strength detonator. A VOD of 4,000 m/s was recorded. The stability
of the mixture was determined to have a Rod Rating of 7 after 28
days.
Example 5
[0059] In a fifth example, TITAN.TM. 7000 emulsion 80% by weight
was mixed with Product B 20% by weight. The mixture was acidified
with a 50% by weight acetic acid solution and then a 25% by weight
sodium nitrite solution was added to the explosive composition at
0.2% by weight of the total explosive composition. This addition
reduced the explosive composition from 1.22 g/cc to 1.03 g/cc. The
explosive composition was loaded into 152 mm diameter PVC pipes and
detonated using a 400 g Pentolite booster fitted with a #12
strength detonator. A VOD of 5,100 m/s was recorded.
Example 6
[0060] In a sixth example, TITAN.TM. 2000 emulsion 60% by weight
was mixed with Product B 10% by weight and ANFO 30% by weight. The
mixture was acidified with a 50% by weight acetic acid solution and
then a 25% by weight sodium nitrite solution was added to the
explosive composition at 0.2% by weight of the total explosive
composition. This addition reduced the explosive composition from
1.23 g/cc to 1.12 g/cc. The explosive composition was loaded into
152 mm diameter PVC pipes and detonated using a 400 g Pentolite
booster fitted with a #12 strength detonator. A VOD of 4,500 m/s
was recorded.
Example 7
[0061] In a seventh example, TITAN.TM. 2000 emulsion 60% by weight
was mixed with Product B 20% by weight and ANFO 20% by weight. The
mixture was acidified with a 50% acetic acid solution and then a
25% by weight sodium nitrite solution was added to the explosive
composition at 0.1% weight of the total explosive composition. This
addition reduced the explosive composition from 1.18 g/cc to 1.10
g/cc. The explosive composition was loaded into 152 mm diameter PVC
pipes and detonated using a 400 g Pentolite booster fitted with a
#12 strength detonator. A VOD of 4,200 m/s was recorded.
Example 8
[0062] In an eighth example, TITAN.TM. 7000 emulsion 80% by weight
was mixed with Product B 20% by weight. The mixture was acidified
with a 50% by weight acetic acid solution and then a 25% by weight
sodium nitrite solution was added to the explosive composition at
0.1% by weight of the total explosive composition. This addition
reduced the explosive composition from 1.22 g/cc to 1.15 g/cc. The
explosive composition was loaded into 152 mm diameter PVC pipes and
detonated using a 400 g Pentolite booster fitted with a #12
strength detonator. A VOD of 4,900 m/s was recorded.
[0063] Rod Rating Testing
[0064] Various components were tested for their stability, as
indicated in Table 2. This test involved mixing the bulking agent,
ANFO and/or emulsion and then monitoring the level of
crystallisation in the emulsion as a function of time. This was
achieved by using a 10 mm glass rod that is dipped into the blend
at a 45 degree angle to a depth of approximately 20 mm to coat one
side of the glass rod with blend. The glass rod is then lightly
tapped to remove excess bulking agent, prill and/or emulsion. The
glass rod is held toward a light source with the side coated with
emulsion is facing away and allowing the light to pass through the
glass rod. The emulsion is than lightly rubbed along the glass rod
three times and the proportion of crystals are measured as
follows:--8=no crystals; 7=small amount of crystals; 6=half
emulsion/half crystals; 5=mostly crystals with some emulsion; 4=All
crystals with no emulsion. The blend is continually rated for the
proportion of crystal formation over time at known intervals.
Example 9
Stability Testing
[0065] A first test was carried out, in accordance with the
invention, using TITAN.TM. 2000 emulsion 80% by weight was mixed
with Product B 20% by weight, and gassed to a density of 0.99 g/cc,
and this gave a Rod Rating of 7 after 28 days.
[0066] In contrast, tests with other substances as the waste
component gave inferior results for the stability of the emulsions.
It is highly preferred that such emulsions must be stable for at
least 14 days, and preferably are stable for 28 days. The test for
stability is preferably the Rod Rating test, described herein, and
a suitable stability will be an emulsion that has a Rod Rating of 6
or higher, for at least 14 days.
[0067] Results for these tests are given in Table 2, below.
TABLE-US-00002 TABLE 2 STABILITY TESTING Density Composition g/cc
Period Rod Rating 80% T2000 and 20% Product B 0.99 28 days.sup. 7
(FIG. 3a) (invention) 80% T2000 and 20% shredded 1.03 .sup. 8 hours
>4 tires (FIG. 3b) 10% comingled plastic shredded 0.95 1 day 4
(FIG. 3c), 54% T2000 and 36% ANFO - no gassing 5% comingled plastic
shredded (FIG. 1.23 1 day 4 3c), 54% T2000 and 36% ANFO - no
gassing 10% HDPE pellets, 54% T2000 and 1.25 28 days.sup. 6 36%
ANFO - no gassing 10% compacted vinyl, 54% T2000 1.21 .sup. 5 days
4 and 36% ANFO - no gassing
[0068] It can be seen from the microscope photographs in FIGS. 3a,
3b and 3c of the various waste material tested, that the material
in accordance with the invention in FIG. 3a has significantly
smoother surfaces and edges, than with the shredded tyres in FIG.
3b or comingled plastics in FIG. 3c. The stability tests in Table 2
show that crystallisation occurs and the emulsion is destabilised
as a result.
Example 10
Testing of Blasting
[0069] Tests were conducted in the field, using blasting
compositions having as the bulking agent the pellets in accordance
with FIGS. 2b and 2d. A site was selected where the natural surface
was drilled with shot holes.
[0070] Results for these tests are given in Table 3, below.
TABLE-US-00003 TABLE 3 Amount Hole Depth Density Sample (kg/hole)
(m) (g/cm3) VOD (m/s) 2b 250 8-10 1.02-1.04 3000 2b 230-310 7-8
0.98-1.06 3800 2d 250 8 0.94-0.98 3900
[0071] The blasting testing involved loading several holes the
emulsion according to the invention. Three shots were tested with
the results as shown in Table 3. The product detonated to high
order and steady state. No fumes were observed to originate for any
of the locations loaded with the blasting emulsion including the
waste plastics bulking agents.
[0072] Delivery of Explosive Composition
[0073] FIG. 1 shows a schematic of a truck used for the manufacture
and delivery of bulk explosives into blastholes at a mine. The
truck (1), which is also known as a mobile processing unit (MPU),
has three sections (10, 20, 30). The first and smallest section
(10) is usually for storage of fuel oil, which traditionally
comprises about just 6% of the ANFO component. The second section
(20) is normally used for storage of the ammonium nitrate for dry
addition. The third section (30) is used for storage of the
ammonium nitrate based emulsion.
[0074] It is preferable that the waste material is approximately
spherical in shape and about 2 to 3 mm in size. This size and shape
allows the material to have similar flow properties to ammonium
nitrate for the dry addition. As a result, the waste material can
be substituted into the second section (20) of the truck. The lack
of fines and the flowability of the waste material allow the second
section (20) to be used for either material (the waste material
pellets or the AN prill) without significant contamination issues.
Furthermore, the lack of sensitivity of the waste material means
that even if there are some remnants of waste material in this
section (20), it will not provide a source of ignition or provide
fuel for the ammonium nitrate prill. Therefore the MPU trucks can
be used for either arrangement and easily re-purposed, to carry
either set of blasting components.
[0075] The MPU truck (1) has an auger (40) which allows the mixing
of the waste material with the emulsion. A density reducing agent
can also be fed into the mixture to reduce the density of the
explosive composition. If the density reducing agent is an alkaline
metal nitrite salt, then a salt solution can be administered
through an inlet port (not shown) into the auger arm (42). The
explosive composition is delivered out the auger (40) into a blast
hole (not shown).
[0076] The blasting composition according to the invention, and its
method of delivery to blastholes is particularly of benefit when
blasting soft, wet ground, such as natural surfaces. The invention
is also on benefit when fume mitigation is of importance, as the
blasts will produce a minimum about of fumes, especially of noxious
NO.sub.x fumes when the nitrogen gas sensitisation is utilised in
the composition.
[0077] In this specification, unless the context clearly indicates
otherwise, the term "comprising" has the non-exclusive meaning of
the word, in the sense of "including at least" rather than the
exclusive meaning in the sense of "consisting only of". The same
applies with corresponding grammatical changes to other forms of
the word such as "comprise", "comprises" and so on.
[0078] Although the invention is described above with reference to
specific embodiments, it will be appreciated by those skilled in
the art that it is not limited to those embodiments, but may also
exist in many other forms.
INDUSTRIAL APPLICABILITY
[0079] The invention can be utilised in industries using blasting
compositions of the invention, including the mining, quarrying, and
construction industries.
* * * * *