Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Abrasive materials from biological sources
BACKGROUND OF THE INVENUON
1. Field of the Invention
Metallic substrates, such as steel or aluminum parts commonly encountered into
the
fabrication of many domestic and industrial equipments, machines and even
vehicles, are
subjected to both atmospheric and/or aquatic corrosion. Therefore, several
surface
treatments have been developed through time to counteract the detrimental
effects of
corrosion upon metal parts. Among thcsc surface treatments, there is plating,
anodizing,
painting and so forth. Prior to surface treatment, surface preparation is
often needed. One
of most applied surface preparation for metal parts consists of sandblasting
with abrasive
material. A jet-propelled abrasive powder is blasted over the metallic surface
at such a
pressure that the powder particles mechanically abrade the surface, hence
removing all
traces of oxide and dirt. The cleaned part is then ready to be subsequently
treated with a
layer or layers of protective coatings such as zinc or paint as examples.
The use of abrasive materials for surface preparation is well known. Powders
made from
abrasive particles can be made of cerarnic or plastic media, depending upon
the targeted
application and substrate properties. Since combinations of abrasive-substrate
are infinite,
and because new materials are constantly fabricated, the needs for innovative
and
performant abrasive materials are increasingly seeked.
In another domain, millions of tons of carcasses of dead animals, both from
land and sea,
are disposed on landfields every year. These carcasses are most of the time
wasted,
unfortunately. However, they represent huge masses of biological matter from
which a
solid material can be extracted. Bones and shells, including egg shells of
laying animals,
represent important biological sources of ceramic-like material that can be
converted into
powders or flakes finally used as abrasive materials. So, if on one end there
are needs for
new abrasive materials and if on an other end there is a possibility to
recycle biological
materials such as bones and egg shells for instance, then, by combining both
situations a
new invention is coming up.
The present invention relates to the fabrication and applications of new
abrasive
materials, as powders or flakes, obtained through thermal and mechanical
processes such
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as incineration or heating followed by crushing and grinding of raw materials
from
various biological sources. The said raw materials can be non-living animal
bones,
animal eggs or sea animal shells. These materials usually, but not
exclusively, contain
organic matter that has to be eliminated from their solid structure prior to
be further used
as abrasive materials. This invention covers the use of the final powders as
abrasive
materials once the organic matter has been eliminated through incineration or
other
thermal treatments. Thus, powders are produced from the inorganic portion of
the initial
animal matter. Depending upon the temperature and time at which the raw
material is
being exposed, most of, or the entire content of water content is gone
simultaneously with
the organic matter. This is where the chemical composition and physical
structure of raw
material is initially altered. The raw material that is too big is size to be
used as a powder
for jet blasting or abrasive paper fabrication is crushed and grinded until
the end product
reaches an average particle size that is suitable for standard blasting
equipment, or
suitable to be used for abrasive papers, abrasive bands and whells
fabrication.
The present invention relates to the transformation of non-living animal
bones, eggs or
shells into powders, said powders being used as abrasive materials. The
abrasive
properties of powders come from the chemical composition and physical
intrinsic
structures of these tatters. the chemical compositions of the animal-source
materials are
altered by the thermal processes they are going through while their physical
structures are
altered by the crushing and/or grinding processes that follow, although
nothing opposes
to the reverse application of the thermal and crushing/grinding processes.
The present invention represents a recycling application of commonly disposed
biological
matter. Incinerated animal-source materials can be used as abrasive powders
since its
solid proportion can be chemically considered as ceramics. These latters being
usually
hard enough to create an abrasive effect upon other solid material when
blasted or sanded
with them. Several applications of the powders obtained form this invention,
given as
examples, but not limited too, as abrasive media can be mentionned : desealing
of welded
stainless steel alloys, rust removal of steel alloys, paint removal on
aluminum aircraft
skins, pre-treatment of concrete blocks, sanding of wood planks prior to
varnishing and
jet blasting for numerous other surface treatments. =
2. Description of Prior Art
Several U.S patents are directly related to inorganic powder particles used as
abrasive
materials for various applications. Among these materials, ceramic and/or
ceramic-like
powders having a hardness that lies between 4 and 8 on the moh scale are use
for what is
commonly called sandblasting, or jet blasting. Considered as surface
preparations
methods, these latters are well known since decades and a wide variety of
powdery
materials for blasting or sanding from papers already exist for may
applications. Abrasive
materials are used to remove scale, rust and other types of metallic oxidation
layers over
metal parts, such as landing gears prior to plating. Other applications of jet
blasting are
paint removal, on aircraft aluminum skins par example, or surface roughing, on
solid
substrates prior to I-IVOF treatments. For oxidation removal, hard particles
jet propelled
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at high velocity over 80 psi arc usually taken, while paint or varnish removal
on soft
substrates are performed with softer particles. For many years, the most
widely used No.
corundum structure, silicon oxide and plastic media.
Abrasives material from biological sources can be used for numerous
applications
including those previously described.
U.S. Patent No. 4,115,076 discloses a non-toxic abrasive material made from an
iron
metallic oxide, a type of ceramic-like compound, for cleaning ferrous metals
by blasting,
prior to painting. This type of oxide is chemically simple in terms of
composition.
Vontell et al disclose in their U.S. Patent No. 4,680,199 a method for
depositing a layer
of abrasive material on a substrute. Although the method described in
performed in a
vacuum chamber is quite complex, it reveals another application of abrasive
particles,
namely their deposition over a substrate to make a layer of these particles
for a specific
application. However, depositing abrasive particles over a substrate such as
paper, by
sticking them with an appropriate binder, may produce sandpapers. Such
material can be
produced with abrasive materials from biological sources.
Aluminum oxide or similar corundum-like compounds, as previously described, is
one of
the most used abrasive materials, particularly used for oxide or rust removal.
Such
material is disclosed in U.S. Patent No. 4,799,938. Among the applications
described into
this patent are the fabrication of grinding bands or discs. A similar compound
used as an
abrasive material is also claimed in U.S. Patent no. 4,906,255.
Other very hard materials, in powdery forms, are also used as abrasives. U.S.
Patents
discloses the use of cemented carbide containing cubic boron nitride, as an
abrasive and
wear resistant material. This type of combined compounds drives the
development of
other powders made from the combinaison of various powdery materials used for
other
applications. In U.S. Patent no. 5,259,147 Falz et al disclose the fabrication
of a granular
abrasive material produced from a dispersion of raw materials containing
alumina,
coumpounds containing silica and other additives. A similar approach can be
exploited
with abrasives from biological sources.
The use of soft abrasive material, such as calcium carbonate powder, is
disclosed in U.S.
Patent No. 5,531,634. However, Schott claims a material that is between 4.00
to 4.50011
the moh's scale when its weight composition is at least 96 %. Egg shells have
an average
hardess of 3.00 and a maximum content of 94% in calcium carbonate.
Nervertheless. egg
shells as a blasting material to remove organic coatings is very efficient.
That what makes
a difference between this latter patent and the present claimed invention.
A method and apparatus for separating a protein membrane and shell material in
waste
egg shells is disclosed in U.S. Patent No. 6,176,376. No mention is given
concerning the
use of egg shells as abrasive material, aside from its disposal.
Finally. U.S. Patent No. 6,824,578 from Uchino et al, discloses a polishing
material made
from abrasive materials mixed with other chemical compounds to increase its
efficiency
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as so. It is possible to mixed abrasive material from biological sources with
other
chemicals as well in order to achieve other abrasive or polishing effects.
In conclusion, nothing was found in the prior art, disclosing the application
of powder
materials from biological sources, as abrasives, materials being bones, egg
shells,
shellfishes shells, oysters. lobsters and other similar sea animals.
Therefore, this
invention has never been claimed prior to this one.
SUMMARY OF THE INVENTION
The present invention relates to the use of powders produced from biological
sources
such as non-living animals, coming from land or sea, once transformed through
various
thermal, crushing and grinding processes. These non-living animals comprise,
for
example, bones from incinerated dead animals, egg shells, oyster shells,
mussels and
other species of shellfishes, corals and fishbones. Dead animals, once
thermally treated to
extract organic matter from inorganic matter, are transformed into clusters,
flakes or
chunks then crushed and grinded into powders. These tatters shall be exempted
of
bacteria, such as salmonella, E-coli, and shall not contain heaver metals or
other toxic
compounds beyond limits that are not considered acceptable depending upon the
targeted
application, country rules and regulation and/or analysed and evaluated such
that is can
be proven not being harmful to environment or toxic toward human exposure,
prior to
their use as abrasive materials.
Powders can be chemically considered as ceramic particles, having altered
structure
caused by thermo-mechanical transformation during their treatment. The
chemistry of the
altered structure of the powders is also altered simultaneously, for instance,
an increase in
bonded oxygen and/or a decrease in water or carbone dioxide content. Both
physical and
chemical properties are different from the raw materials they come from, prior
to
transformation. Once heated, crushed and/or grinded at various sizes,
preferably between
0,1 mm and 4,0 mm, powders, as is or mixed with other powder types and/or
other
compounds, may be used as abrasive material, as jet blasting media or as
sandpaper
media. They may also be used in composite abrasive material, as mixed with
other
materials such as ceramics, metals or polymers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention is now explained in more details with descriptions of preferred
applications
and examples.
Abrasive particles draw their applications as such from their intrinsic
physical properties.
These tatters include hardness, resilience, density, structural geometry and
other factors.
For example, bones from animals having an average hardness of 5 on the moh
scale but
are less resilient than aluminum oxide, or corundum. The chemical composition
of bones
is basically a mixture of calcium phosphate, calcium carbonate, calcium
fluoride and
magnesium phosphate. Once exposed to heat above 250 degrees celcius, a bone
loses its
water content, and its initial cristalline structure is therefore altered.
This latter is even
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more altered after crushing and grinding. however, its average harness is high
enough to
bc used as an abrasive media, thus, representing a part of this claimed
invention, namely
the use of such material for application as an abrasive material.
Eggs. from hens, quails, turkeys and other laying animals, are described, in
this
invention, under the same considerations than animal bones. The chemical
composition
of eggs is moreless similar to bones, namely, a mixture of calcium carbonate,
magnesium
carbonate and calcium phosphate. However, the hardness of egg shells is lower
than
bones, about 3 on the moh scale. Hence, its properties as abrasive material
are different
since it is softer and less resilient than bone powder. It makes it more
appropriate to be
used to remove organic coatings such as paint or varnish on softer substrates.
Shells from
shellfishes, such as lobsters, crabs, shrimps, mussels, oysters and other
similar animals
are chemically closer to eggs than bones. The main compound encountered in
these types
of shells is calcium carbonate. Shells from shellfishes are more resilient
than eggs.
Once freed from their organic matter content by an appropriate thermal
treatment, bones,
eggs or shells can be considered as inorganic compounds, similar to ceramics.
However,
thermal treatments, depending upon the process being used, alter the structure
of the
initial solid raw material. Furthermore, subsequent mechanical treatments such
as
crushing and grinding, alter even more the structure of the solid matter. In
consequence,
processed powders obtained from biological sources are different in structure,
composition and properties than original solid raw material. Nevertheless, the
obtained
powders can be used as abrasive materials although they are not exactly of the
same
composition and structure than the original matter.
The use of all powders issued from non-living animals remains such as bones,
or eggs
and shells, thermally and mechanically treated, as abrasive materials
represents an
innovative application of such matter, justifying this disclosed invention.
EXAMPLE NO.1
Domestic or farm animals are incinerated for 4 hours at 250 degrees celcius
into a
furnace, to eliminate organic matter and water molecules, thereafter, only
bones from
these animals remain. The bones are subsequently collected from furnace once
temperature allows their manipulation and they are crushed and grinded until
an average
2,0 mm particle size is obtained. Particles of powder are then put into a
sandblasting
equipment settled to propel particles at a pressure of 60 psi. Target being a
rusted steel
parts, the particles are jet blasted at a distance of 12 inches with an angle
of 90 degrees
between the target and the nozzle of the blasting machine. Jot blasting is
maintained until
all the rust at the surface of the target is gone.
EXAMPLE NO.2
Hens egg shells are heated at 150 degrees ecicius for 2 hours, after an
extraction from the
liquidous substance they bear. The heat destroys all remaining organic matter
that covers
the shell flakes, including bacterial load, and dehydrates the egg shell
structure. Egg shell
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flakes are subsequently collected from furnace once temperature allows
manipulation and
then crushed until an average 1,5 mm particle size is obtained. Particles are
then put into
a sandblasting equipment settled to propel particles at a pressure of 80 psi.
Target being a
painted aluminum part, the particles are jet blasted at a distance of 9 inches
with an angle
of 70 degrees between the target and the nozzle of the blasting machine. Jet
blasting is
maintained until all the paint at the surface of the target is gone.
EXAMPLE NO.3
An abrasive powder made from animal bones, said powder being crushed and
grinded to
an average particle size of 2,0 ram is projected on steel parts to remove heat
scale prior to
machining, at a jet pressure of 90 psi, with a jet-target distance of 5 inches
at a 60-degree
angle until scale is completely removed.
EXAMPLE NO.4
An abrasive powder made from egg shells, said powder being crushed to an
average
particle size of 1,0 mm is projected on aluminum sheets of aircraft to remove
old paint
prior to chemical conversion coating followed by painting, at a jet pressure
of 50 psi,
with a jet-target distance of 4 inches at a 45-degree angle until old paint is
totally
removed.
EXAMPLE NO.5
An abrasive powder made from shellfishes, crab shells and mussels, said powder
being
crushed and grinded to an average particle size of 1,5 mm is projected on
concrete blocks
to remove staining prior to sealing followed by painting, at a jet pressure of
40 psi, with a
jet-target distance of 5 inches at a 80-degree angle until stains and dirt are
totally
removed.
EXAMPLE NO.6
An abrasive powder made from egg shells, said powder being crushed to an
average
particle size of 1,0 mm is glued on a 144 square inches sheet of paper, hence
creating a
standard sand paper, to remove roughness and small defects on wood planks,
such as oak
or pine, prior to varnishing.
EXAMPLE NO.7
An abrasive powder made from a mixture of bones and shellfishes, said powder
being
crushed to an average particle size of 0,8 mm is glued on a 144 square inches
sheet of
paper, hence creating a standard sand paper, to remove oxidation and small
defects on
steel parts, prior to surface finishing, such as plating or HVOF.
