Note: Descriptions are shown in the official language in which they were submitted.
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
1
1 SELF-REMEDIATING PROJECTILE
FIELD OF THE INVENTION
This invention is directed to ballistic projectiles and their environmental
remediation,
and related products and materials.
BACKGROUND OF THE INVENTION
The solubility of lead in water (plumbo-solvicity) is a known phenomenon. Pure
lead
in soft water will yield concentrations of soluble lead levels of above
0.75mg/litre at pH 7.5
within days to weeks. (FIG 1.) Lead-antimony alloys will dissolve at a much
faster rate and
achieve much higher levels of soluble lead owing to Redox reactions of the
lead and
antimony present in the alloy. (FIG 2.)
Lead-antimony alloys are extensively used for ballistics applications such as
bullets
and shot. Such lead alloy usage is in the region of 200-300,000 tons per annum
worldwide.
When bullets or shot are fired on ranges they can, under adverse conditions,
give rise to
significant pollution through the solublisation and corrosion of the lead-
antimony alloy in a
concentrated area. The costs involved in the removal of this pollution are
substantial.
Remediation might require the site to be acid-washed or the application of
remediating agents
to the whole site.
To avoid this pollution, others have attempted to coat lead ammunition
products with
impermeable inert barriers to the surface of the metal to provide a barrier to
dissolution and
corrosion. The principal problem with that approach is that, when the
ammunition projectile
is fired, the acts of firing, barrel abrasion, collision with other
projectiles, and impact with the
target or ground cause breaches in the coating. Such breaches remove the
integrity of the
coating and provide a route for the lead to solubilize and pollute. Thus, such
barriers impart
no environmental advantage.
In addition to lead, other metals, their alloys and their composites have been
used as
ballistic projectiles, including antimony, bismuth, chromium, cobalt, copper,
depleted
uranium (DU), tantalum, tin, tungsten, and nickel. Also, certain heavy metals
and their alloys
in the form of fibers, strips, and/or flakes are used in ballistic shells as
chaff rounds or 'radar
flares' to obscure potential missile targets or to deflect incoming missiles.
Thus, the term
"projectile" can be more fully described as a body in any physical form,
including bullet,
shot, pellet, slug, shell, missile, fiber, and foil, which is propelled at
force by an explosive
device, or indeed, any other form of physical or mechanical propulsion.
Like lead projectiles, most other metal projectiles and/or their corrosion
products are
potentially harmful to people and the environment:
=Copper and its salts are frequently regarded as toxic, and certain compounds
are
SARA 313 Register materials.
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
2
1 =Bismuth has been associated with Alzheimer's-like dementia.
=Depleted uranium (DU) is at least as toxic as lead, and recently has been
shown to
exhibit mutagenic and genotoxic properties.
=Pure tin is usually deemed innocuous to humans. However, it is toxic to
microorganisms in the environment. Ballistic tin is usually used as an alloy
with other metals
such as antimony or bismuth owing to its potential transform from grey to
white tin on firing.
This phenomenon of pure tin could risk barrel blocking. Tin in its ballistic
alloys can
undergo redox corrosion to liberate bismuth and antimony compounds.
=Tungsten-nickel-iron alloys and composites, frequently referred to as "heavy
steel"
or "heavy metal tungsten alloy" (HMTA), can corrode under oxygenating
conditions to
liberate oxides and salts. Additionally, in recent studies HMTA has been shown
to exhibit
genotoxic and mutagenic properties. Despite its low solubility, even tungsten
carbide has
been shown to be bio-available. Tungsten is a known 'reproductive affecter',
and tungsten-
nylon composite residues have been shown to be soluble under certain
groundwater
conditions, increasing its potential bioavailability. Furthermore, tungsten
has been shown to
be eco-toxic.
=Fine nickel and certain of its compounds are known carcinogens. Such
materials can
be liberated by the corrosion of low-cost mild steel and soft iron shot.
=Antimony is a known toxic and regulated material.
There is a compelling need for environmentally self-remediating ammunition and
projectiles, whether made of lead or other materials.
SUIVIMARY OF THE INVENTION
According to the invention, a self-remediating projectile is provided. In one
aspect of
the invention, a conventional metal bullet, shot, slug, shell, pellet, fiber,
foil, missile, etc. is
coated or otherwise treated, in whole or in part, with a remediation agent,
preferably in a
binder, i.e., a polymeric matrix. The binder is typically water-soluble and/or
biodegradable.
The remediation agent (sometimes called an environmental remediation agent)
comprises one
or more materials capable of reducing or preventing the water-solubility of
the projectile
metal(s), or containing it within the vicinity where it lands when fired,
thereby preventing or
diminishing the leaching of the metal(s) into the environment. A partial list
of remediation
agents includes calcium and magnesium sulfides, oxides, and phosphates.
Through careful
selection of the remediation agent(s), the invention offers the benefit of
rendering all of the
metals in a projectile --not just lead-- self-remediating.
A method of making a self-remediating projectile is also provided and
comprises
coating or otherwise treating a metal projectile with an organic solvent
solution (or other
mixture) of a binder polymer and a remediation agent; and drying the coated
article. A
technique such as tumble rolling can be utilized. In one embodiment, the
projectile is coated
CA 02547319 2009-02-23
3
1 or treated with an excess of remediation agent, thereby providing the
advantage of potentially
"shooting clean" a contaminated area through repeated firing of self-
remediating projectiles
into the contaminated area.
In anotller aspect of the invention, a self-remediating target, such as a clay
pigeon, is
provided and comprises a rernediation agent coated on or otherwise applied to
all or part of
the target. The resulting targets can then be used to clean up a contaminated
area, such as a
shooting range, by "shooting clean" the area.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will become better understood when considered in conjunetion
with the
following detailed description and accompanying drawings, wherein:
FIG. 1 is a graph showing the corrosion of a 2mm shot of 99.999% pure lead
immersed in water for 100 days.
FIG. 2 is a graph showing the corrosion of a U.S. No. 8 lead-2% antimony shot
immersed in water for 100 days. (Note: although the shot was sold as nominally
containing
2% antimony, it actually assayed at 1.25% antimony (w/w).)
FIG. 3 is a schematic, partially cross-sectional view of a self-remediating,
copper-
jacketed, lead-antimony alloy bullet according to one embodiment of the
invention, and
FIG. 4 is a graph showing the corrosion of a post-firing, self-remediating,
No. 8 lead-
2% antimony shot according to one embodiment of the invention irrunersed in
water for 100
days. (See the note above in the description of Fig.2.)
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, a self-remediating projectile is provided.
In one
embodiment, a time-release coating containing a remediation agent is applied
to a round of
arnmunition or other projectile, effectively rendering the coated article
environmentally self-
remediating. The principles of Integrated Fixation Systems ("IFS") detailed in
United
States issued Patent 6,838,504
are applied to lead or other n7etal ammunition or projectiles
such that they are pre-treated in advance of being disposed of, thus avoiding
the
inconvenience of regularly de-leading ranges and other locales, and thereby
avoiding or
reducing substantial site remediation costs. Niinimal reagent is required, and
there is thus no
need to treat areas of the site on which the spent projectile does not fall.
A self-remediating projectile according to the invention has a reduced -
tendency to
leach metal(s) into the environment, as a consequence of the metal(s) being
passivated or
rendered less water soluble than normal. Even post-firing, the projectile is
protected by a
passivating coating formed thereon. The invention is designed to work with any
metal
projectile, be it a bullet, shot, slug, shell, pellet, fiber, foil (e.g.,
chaff), or even a missil.e. The
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
4
1 projectile may be a pure metal, a metal containing one or more impurities,
an alloy, a metal-
metal or metal-non-metal composite, or any other metal-containing or metallic
substance.
The projectile may be made of a combination of metallic substances. A
nonlimiting list of
metallic elements used in the manufacture of ammunition and other projectiles
includes lead,
antimony, bismuth, chromium, cobalt, copper, nickel, tin, tungsten, tantalum,
and uranium.
Iron (typically in the form of a steel jacket), is another example.
In one embodiment, a surface coating (sometimes referred to as an "integrated
fixation system" or "IFS" coating) comprises a remediation agent carried in a
binder, i.e., a
polymeric matrix. The coating is conveniently prepared by dissolving a polymer
in an
organic solvent, adding a remediation agent, coating a projectile, and drying
the projectile. In
some embodiments, the surface of the metal projectile is physically or
chemically scored,
etched, or otherwise treated prior to being coated with an integrated fixation
system, to
improve the bond between the coating and the metal. The resulting self-
remediating
projectile can thus be characterized as a metal projectile having an
integrated fixation system
coated thereon, wherein the metal projectile has a surface adapted to
facilitate strong
adherence between the integrated fixation system and the metal projectile.
Nonlimiting examples of binder polymers include acrylic acid copolymers;
copolymers of esters (e.g., vinyl acetate), amides (e.g., acrylamide), and/or
vinyl alcohols;
polyethylene glycols and glycol copolymers; hydratable cellulose compounds;
and
carboxylated copolymers of such materials. More generally, the binder polymer
is any
coatable, water-soluble or biodegradable polymer capable of adhering to lead
or other heavy
metal and releasing a remediation agent upon dissolution or degradation in
water. Preferred
polymers are pH-neutral, linear, and non-toxic (LD50 in mammals less than
5,000mg/Kg). A
variety of acrylic copolymers are available from suppliers such as Ciba-Geigy,
Harco (UK),
and Yule-Catto (UK).
A preferred binder polymer comprises a cation-capped copolymer of acrylic acid
and
an acrylic ester. For example, a copolymer of acrylic acid and methyl acrylate
is prepared
and then allowed to react with a hydroxyalkylamine, e.g., triethanolamine
("tris"). One such
polymer comprises poly[(methyl acrylate)X(tris-capped acrylic acid)y], with
the mole ratio of
x:y being approximately 87:13. If excess tris is used, it has a plasticizing
effect and helps
condition the surface of a lead projectile to be coated; that is, it
facilitates partial hydrolysis
(corrosion) of the surface. From this it can be seen that copolymers capable
of hydrogen
bonding (e.g., carboxylated and/or hydroxylated polymers) should bind well to
a metal
surface.
Another copolymer for use as a binder polymer comprises poly(vinyl
acetate)x(tris-
capped acrylic acid)y, where x:y is approximately:94:6.
In each of the above two cases, the number of monomer repeat units (sum of
x+y) in
the copolymers will typically range from approximately 250 to 1500.
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
1 In one embodiment, the binder polymer, when applied to a metal bullet or
other
projectile, forms a matrix that is rendered at least as flexible as the heavy
metal to which it is
applied, and facilitates environmentally self-remediation of the underlying
metal bullet or
other projectile. This flexibility is induced by, e.g., internal
plasticization by pendant
5 moieties on the polymer or by the external addition of plasticizers to the
matrix. A
nonlimiting list of plasticizers includes alcohols, amines, ethers, esters and
co-compounds
thereof.
The binder polymer is dissolved in an organic solvent, preferably one having
low or
substantially no toxicity to mammals. Nonlimiting examples of solvents include
esters,
alcohols, and ethers (e.g., solvents used in paints and inks). Specific
examples include ethyl
acetate and propanol (e.g., propan-2-ol). . Ideally, the solvent (or mixture
of solvents)
facilitates good film formation upon drying, and minimizes tack of the coated
article.
Optionally, additives such as methoxy, ethoxy, and/or hydroxy adducts of
ethane, propane,
and butane (e.g.) and other conventional anti-blocking aids are added to lower
the resulting
tack of the coated article.
The polymer solution is combined with one or more environmental remediation
agent,
i.e., an agent (plural or singular) capable of reducing the solubility of
toxic metal ions and/or
acting on potentially water-soluble heavy metals to prevent them from becoming
soluble.
Preferably, the remediation agent is capable of reducing the water-solubility
of a heavy metal
below the maximum amount permitted by statute, e.g., the U.S.-U.T.S.
(Universal Treatment
Standards) limits.
Nonlimiting examples of remediation agents include one or more of calcium (or
magnesium) sulfide, phosphate, hydroxide, carbonate, oxide, or apatite;, di-
calcium hydrogen
phosphate; calcium di-hydrogen phosphate; triple super phosphate; dolomite;
phosphoric
acid; and/or mixed calcium-magnesium adducts of the aforementioned agents.
"Triple super
phosphate" (TSP) is Ca(H2P04)2=H20 (CAS No. 65996-95-4). Ideally, the
remediation
agent(s) is selected to work with all of the metals in a given projectile.
Thus, while
phosphates used alone can remediate lead, they do not work with common lead
additives
such as arsenic or antimony. Phosphates in combination with calcium sulfide
and calcium
carbonate and/or calcium oxide and/or calcium hydroxide (hydrated lime)
however, should be
capable of remediating virtually all metals of Group III and higher, including
depleted
uranium.
Preferred remediation agents are the Molecular Bonding System (MBSTM) brand of
remediation agents available from Solucorp Industries (West Nyack, NY) For
example, MBS
3.1TM is a 3:2:1 wt.-to-wt. (w/w) powder mixture of technical grade calcium
sulfide, calcium
carbonate, and triple super phosphate. MBS 2.1Tm has the advantage of not
adversely
affecting the density of a coated metal projectile.
The amount of remediation agent(s) that is used will depend on the size, mass,
and
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
6
1 type of projectile that is being treated, and in some embodiments, on the
environment in
which the projectile is likely to be used, with the aim being to passivate
and/or lower the
water-solubility of the projectile metal(s). In some embodiments, an excess of
remediation
agent(s) is used. The resulting treated projectile can then be used to "shoot
clean" a
contaminated area, such as a shooting range. Heavy metals pollution already
present in the
area can be treated through the repeated firing of environmentally remediating
ammunition
into the area. Thus, the invention also provides a method of remediating an
area
contaminated with spent ammunition, comprising shooting clean the area with
self-
remediating ammunition, preferably self-remediating ammunition containing an
excess of
one or more remediation agents.
In one embodiment of the invention, an environmentally self-remediating bullet
or
other metal projectile is made by coating the metal article with an organic
solvent solution (or
other mixture) of a binder polymer and a remediation agent, followed by drying
the coated
article to drive off the solvent. A nonlimiting example of a suitable coating
technique is
"tumble rolling." The article to be coated (e.g., a lead slug or shot) is
rolled in the binder-
remediation agent solution until evenly coated, and the solvent is then
evaporated or
otherwise driven off, (taking care to minimize any fire hazard). Optionally,
the evaporated
solvent is burned or, more preferably, condensed and reused. Optionally,
precautions are
taken against formation of excess static charge. Optionally, the article can
be "over-rolled"
when dry to give it a fine, smooth, glossy, black finish. (This is
particularly suitable for shot
or other ammunition where it is desirable to maintain an appearance familiar
to the end user,
but unnecessary where the slug will later be copper-jacketed or otherwise
hidden from view.)
Figure 3 shows a nonlimiting example of a copper-jacketed lead-antimony alloy
bullet
prepared in accordance with to the invention. The projectile (10) includes a
lead alloy core
(12) coated with an IFS coating (14). A steel piercing tip (16) sits atop the
slug. Although
not shown, the piercing tip, like the slug, can be coated with an IFS coating.
The slug-tip
combination is sheathed in a copper jacket (18).
Swaging and other methods for making ammunition are well known. A lead alloy
(e.g.) is extruded as a wire, which is then snipped into cylindrical sections
or cores. These
cores can be coned at one end by insertion in a press (as in the case, e.g.,
of a 7.62mm round).
A small copper cup (pre-formed) is pressed in a series of operations into a
copper bullet
jacket. The core is inserted into the open back end, and the rim of the copper
jacket is
swaged over to seal the lead core into the jacket. The bullet is then re-
pressed to give it the
exact size needed to fit into the barrel
A self-remediating round of ammunition is conveniently prepared by making a
slightly undersized metal core, coating it with an IFS coating, swaging a
copper jacket about
the core (and optionally a piercing tip). In the case of lead, which has a
density of 11.3, it is
convenient to make a 5% undersized lead core and coat it with 1% by weight of
an IFS
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
7
1 coating (which has a density of circa 2g/cc). The coated core is swaged in
exactly the same
manner as an uncoated core, and yields a jacketed slug that weighs about 2-3%
less than an
uncoated slug, i.e., the weight discrepancy is within normal production
variance. In a
5.56mm M- 16 round, there is a steel piercing tip added to the copper jacket
before the core.
The invention has the advantage of not being limited by the size of the
projectile. It
can be applied to all calibers of rounds, including calibers of 9mm and above,
whereas
similar large caliber rounds made with purportedly non-toxic alternatives such
as tungsten-
nylon matrix can become physically unstable and frangible, rendering them
liable to
disintegrate on firing, with potentially dangerous consequences. Additionally
the invention
does not affect the long-term physically integrity of the projectile through
adverse chemical
interactions. In contrast, other non-toxic metal alternatives may become
frangible and
physically unstable on storage, through action of (1) adverse redox reactions
between
incompatible metal components, as may occur with copper-iron and tungsten-
steel
composites, and/or (2) degradation through thermo-chemical oxidative
decomposition
(sometimes known as plastic cancer) of their polymer composites, which can be
accelerated
by the proximity of the polymers to certain finely dispersed metals, e.g., as
can occur with
tungsten-polymer composites.
The invention does not require the coating to fully envelop the metal core.
The
enclosure of the spent projectile is achieved post-firing through hydration of
the coating and
release of the remediating reagent, which renders non-hazardous solubilized
lead and creates
a stable corrosion product over the surface of the potentially polluting item.
In another embodiment of the invention, the metal item is pre-treated or co-
treated
with a surface conditioning agent during application of the polymer so as to
facilitate the
partial passivation (corrosion) of the metal surface, and thereby facilitate a
strong adhesion
between the polymer matrix and the metal surface. A nonlimiting list of agents
includes
amines and their co-compounds, e.g., triethanolamine, triethylamine, related
organic
triamines, diamines, alkyl or aryl amines, and salts of the aforementioned
compounds.
The following is a nonlimiting example of the invention.
Example 1. A surface coating is prepared by forming a solution of (a) a linear
copolymer polymer comprising poly[(methyl acrylate),t(tris-capped acrylic
acid)y], where x:y
is approximately 87:13 (100 parts by weight (pbw)), (b) ethyl acetate (100pbw)
and (c)
propan-2-ol (100pbw). This coating imparts moisture resistance to a coated
metal article but,
on immersion in water for more than a few hours, readily hydrates, crumbles
and dissolves
over a period of several days to weeks. Being a soluble acrylic polymer, it is
intrinsically
biodegradable.
The polymer solution is combined with a remediation agent known as Molecular
Bonding System 3.1Tm from Solucorp Industries: a 3:2:1 wt.-to-wt. mixture of
technical
grade calcium sulfide, calcium carbonate, and triple super phosphate) (200
pbw) and
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
8
1 additional ethyl acetate (300 pbw) to form the IFS coating.
The IFS coating is applied to a US No.8 lead - 1.25% antimony alloy shot at a
concentration of 1% by weight (dry weight) by a tumble rolling technique,
followed by
evaporation of the solvents.
The invention permits lead bullet slugs e.g., 5.56mm or 7.62mm or larger
caliber slug
cores, to be similarly coated, jacketed, and/or further processed without
significant deviation
from existing swaged bullet manufacturing processes.
IFS-coated shot prepared according to Example 1 was loaded into 12 gauge
cartridges
and fired. The post-fired shot was recovered and displayed the scars of
surface disruption
due to barrel abrasion and impact between pellets in flight and on impact with
the ballistic
target. The coating had the quality of both adhesion to the metal, in that it
was not easily
removed by the abrasion of the shooting process, and flexibility in that it
remained on the
surface of the lead pellet, whatever shape it assumed. This quality should
permit the coating
to remain in intimate and firm contact with a lead slug or other projectile
even during the
conventional swaging process used in bullet manufacture. Upon visual
examination, the
coating on the recovered shot was judged to have been disrupted in about 5% of
its surface
area.
The ballistic qualities of the shot were evaluated at 25 yards and 40 yards,
and the
spread was found to be not substantively different from that of uncoated shot
pellets under
the same conditions, there being only a 3.5% reduction in the density of the
shot imparted by
the applications of the IFS coating.
The post-fired shot was immersed in water at a rate of 10 parts shot to 100
parts
water, and the coating noticeably degraded over several days, releasing the
active remediating
agent. The shot was rendered black, with a stable corrosion product that
covered the whole
surface of the lead shot, including the once potentially soluble exposed lead
surfaces. Soluble
lead was monitored over time, and leaching was observed to be at or below
normal levels of
detection (0.010mg/Litre at 90% certainty) even after 100 days leaching
(FIG.4). The
Comparable US-UTS limit for lead is 0.75mg/Litre after 1 day leaching.
Importantly, the
leaching had been stemmed by a stable, corrosion-resistant coating that had
been formed after
the firing process.
Comparative leaching results are summarized in Table 1. Expected lead shot
corrosion rates of circa 10,000 years in temperate regions and >1,000 years in
tropical regions
have been cited in the literature. (See "Contaminatiofz at Shootifzg Ranges, "
Dr. Corrine
Rooney, Soil Plant and Ecological Sciences Division Lincoln University,
Canterbury, New
Zealand http://www.lead.org.au/fs/shootingranges.pdf.) Our studies suggest
that, given a
surfeit of rain, pure lead shot might last 21,000 years, but commercial lead-
1.25% antimony
alloy shot would survive only 1,200 year. By contrast, the corrosion rate of
the IFS-protected
shot implied a corrosion time of circa 1.49 million years, indicating
substantial environmental
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
9
1 utility to IFS-treated shot.
Table 1. Comparative Corrosion Rates for US No.8 Shot Based on Lead
Leaching
Linear Relative Implied
Sample Slope Corrosioa Corrosion
amg/Litre/day Rate Years
Pure 0.0129 0.057 21,238
Lead
Lead-Antimony 0.228 1.00 1,179
Shot
Lead-Antimony 0.00018 0.001 1,493,455
Shot + 1% IFS
Although not bound by theory, it is believed that, upon release from the
polymeric
matrix, the remediation agent forms a cement-like structure that sheathes the
metal slug or
other metal article, in effect forming a "calcolith." The invention is
intended to reduce the
solubility of metals commonly used in ammunition and other projectiles, and,
advantageously, to passivate corroding surfaces of such metals, their alloys
and composite
alloys. The integrated fixation system described herein should, therefore, be
of tremendous
value in remediating these environmentally harmful ammunition materials,
including
tungsten-nickel steels commonly used as piercing tips in military 5.56mm
ammunition.
Materials chosen for the IFS polymer matrix and the remediation reagent, are
preferably selected from a group of materials that are known to be -- or from
their known
chemistry are reasonably anticipated to be -- of low toxicity, and as a
consequence they are
not likely to cause long term toxicity to a wounded person and/or animal,
should accidental or
incidental wounding occur by the use or abuse of an IFS projected projectile.
This should be
of tremendous benefit to individuals unfortunate enough to be inflicted with a
gunshot
wound. It is common surgical practice in treating gunshot wounds that, if the
slug is still in-
situ, it is not removed unless it is easily accessible by the surgeon. The
justification for this
practice is that poking around for the bullet in a trauma victim can do more
harm than good.
Thus, wounded individuals have been known to carry lead slugs within them for
prolonged
periods (in the case of one WWI casualty, as long as 80 years). Although the
wound itself is
by far the greater problem, the long-term toxicity posed by the slug or
shrapnel should be
diminished greatly through use of this invention.
CA 02547319 2006-05-25
WO 2005/119166 PCT/US2004/039732
1 The invention has been described with reference to various embodiments,
figures, and
examples, but is not limited thereto. For example, just as a projectile can be
coated with an
excess of remediation agent and used to "shoot clean" a contaminated area, a
remediation
agent can be coated on or otherwise applied to a projectile used as a target,
such as a clay
5 pigeon, which can similarly be used to remediate a contaminated area by
shooting it clean.
For trap shooting and similar pastimes, target weight regulations may limit
the amount of
reagent that can be applied to the sporting clay or other target. The
following example
illustrates this aspect of the invention
10 Example 2. A surface coating is prepared by forming a dispersion of MBS
2.1TM
(Solucorp Industries Ltd.) in polyvinyl acetate-polyvinyl alcohol, (PVAcx
PVAy, where the
mole ratio x is >=65%). Specifically, a blend of 20%w/w/ PVAc-PVA solution,
MBS 2.1 Tm,
and ethyl acetate solvent are mixed together at the ratio 1:2:1 pbw. 10 gram
of the resulting
dispersion is applied to the underside of a normal commercial or biodegradable
clay pigeon,
such as those supplied by CCI International Ltd (of Priors Haw Road, Corby,
Northants,
UK). On drying, the weight of the standard sized clay pigeon should be within
the weight
range 100-110 grams and will carry 4-5 grams of an IFS reagent, which may be
liberated by
biodegradation and or weathering to release sufficient reagent to remediate
approximately 2.0
to 2.5 grams of soluble lead or passivate the surface against corrosion of a
much larger
proportion metallic lead shot. The above dispersion may be modified into a
sprayable paint
or re-formulated into an aqueous sprayable paint to facility mass manufacture.
From the preceding discussion and example, it can be seen that the invention
also
provides an environmentally remediating target comprising a clay sporting
pigeon coated or
otherwise treated with at least one environmental remediation agent.
Preferably, the at least
one environmental remediation agent is contained in a polymer binder. The
invention also
provides a method of remediating an area contaminated with spent ammunition,
comprising
shooting clean the area using self-remediating ammunition and clay sporting
pigeons treated
with at least one environmental remediation agent.
Persons having skill in the art to which the invention pertains will
appreciate that the
invention can be further modified without departure from the principles
described herein, and
without leaving the full scope of the invention, which is only limited by the
appended claims.
