Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Amorphous Silica Products and Methods of Producing Amorphous Silica Products
INVENTORS
Scott D. Trom
Bernard G. Pike
RELATED APPLICATION
[0001]. This application claims priority to US provisional patent
application No. 62/620,570 filed
on January 23, 2018 which is hereby incorporated by reference and as a
continuation-in-part to United
States Patent Application No. 16/255,302 filed on January 23, 2019.
TECHNICAL FIELD
[0002]. Embodiments of the method of invention comprise producing amorphous
silica glass
particles, sheets, fibers, articles, or other amorphous silicate products from
natural crystalline silica
sand, or glass cullet. Natural silica sand is comprised almost entirely of the
crystalline form of the
silica. However, airborne crystalline silica has been determined to be a
hazardous substance that has
been shown to cause silicosis if inhaled.
[0003]. Embodiments of a method include heating crystalline silica sand,
gravel, or other
particles, (as used herein "crystalline silica sand") glass cullet, recycled
glass, or other glass (as used
herein "glass cullet" or "cullet") or a combination thereof to a temperature
in which the crystalline
silica is converted into amorphous silica sand, gravel, or other particles,
sheets, or fibers. The
crystalline silica sand, gravel, or other particles, glass cullet, recycled
glass, or a combination thereof
may be mixed with other components to provide the desired properties to assist
in processing and/or
product properties such as, but not limited to, melting temperature, melt
viscosity, process efficiency,
density, toughness, hardness, or other desired properties. The amorphous
silica particles, gravel, or
other particles, sheets or fibers may be used as a safe replacement for
crystalline silica sand, gravel, or
particles, sheets or fibers in consumer and industrial applications wherein
dust may be produced
during use or installation, for example.
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[0004]. For example, the crystalline silica sand, glass cullet or a
combination thereof may be
heated in the presence of fluxing components, density increasing components,
hardness increasing
components and other property enhancing components. The density increasing
components may be
metal oxides, metal silicates, silicides, aluminum oxide, zirconium oxide,
clays comprising aluminum
oxide, zirconium oxide, or a combination of aluminum oxide, iron oxide, and
zirconium oxide. Other
density increasing components include titanium oxide and other transition
metal oxides.
[0005]. Thermal (fuse or melt) processing of crystalline-silica containing
minerals (comprising
quartz sands and heavy mineral sands) or recycled glass assures the conversion
of their crystalline silica
content into amorphous silica sands, gravel, or other particles, sheets, or
fibers, and, also, kills any
microbes present in the feed streams. Therefore, the amorphous silica products
are microbe free.
[0006]. Embodiments also include products produced from the amorphous
silica sand, gravel or
other particles, sheets, or fibers. For example, embodiments of the products
include crystalline silica
free sand, gravel, cullet, blasting abrasives, concrete mixes, grout,
manufactured stone, mortar, bricks,
concrete blocks, other concrete products, pavers, and other products that
would benefit and safer with
the replacement of crystalline silica with amorphous silica. The amorphous
silica products may be a
direct replacement for the crystalline silica products.
BACKGROUND
[0007]. Crystalline silica is the most abundant mineral on earth. Due to
its abundance and low
cost, crystalline silica sand, gravel, and rocks have been used for many
industrial and consumer
applications, including hydraulic fracturing sand, glass production, foundry
sand, building materials,
sand blasting, recreational sand, as well as other uses. Gravel or coarse
aggregate shall herein be
defined as any aggregate larger than about 3/16 of an inch. Sand or fine
aggregate is defined as any
aggregate less than about 3/16 of inch with silt being considered the smallest
particles.
[0008]. However, it has been found that respirable airborne particles of
crystalline silica sand
may enter the lungs of people in and around any area. Respirable crystalline
silica sand in the lungs
may result in the development of silicosis and a host of other illnesses.
Silicosis is one of the world's
oldest known occupational diseases, with reports of employees contracting the
disease dating back to
ancient Greece.
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[0009]. Airborne crystalline silica dust may be produced during the
manufacturing process of
the crystalline silica products and also during use or installation of the
crystalline silica products. For
example, respirable crystalline silica dust becomes airborne, such as during
blasting with sand and
cutting concrete or bricks, for example.
[0010]. Abrasive blasting uses compressed air or water to direct a high
velocity stream of an
abrasive material to clean an object or surface, remove burrs, apply a texture
or prepare a surface for
painting. Abrasive blasting is more commonly known as sandblasting since
silica sand is commonly
used as the abrasive, although not the only one always used. Industries that
rely on sandblasting on a
daily or regular basis include painter who work on large structures like
bridges, granite monument
makers, foundries and shipbuilders. Industries that rely on sandblasting on a
daily or regular basis
include any one doing surface preparation work or restoration on large
structures like bridges, tanks,
pipelines, heavy equipment, shipbuilders, or concrete restoration.
[0011]. The term "silica" broadly refers to the mineral compound silicon
dioxide (SiO2).
Although silica can be crystalline or amorphous in form, only the natural
crystalline form of silica (and
its polymorphs) is hazardous to users that may inhale crystalline silica dust.
Owing to its abundance,
unique physical and chemical properties, crystalline silica has many uses.
Common, commercially
produced silica products include quartzite, tripoli, gannister, chert, and
novaculite. Crystalline silica
also occurs in nature as agate, amethyst, chalcedony, cristobalite, flint,
quartz, tridymite, and, in its
most common form, silica sand.
[0012]. Silica sand has been used for many products throughout human
history, but one of its
most common use is in the production of glass. Table 1-1 summarizes other uses
for sand and gravel.
In some instances, grinding of sand, gravel, or products containing
crystalline silica sand or gravel is
required, producing and increasing levels of dust containing hazardous
respirable crystalline silica.
Product Major End Use
Sand
Glass Making Containers, flat (plate and window), specialty, fiberglass (un-
ground or ground)
Foundry Molding and core, molding and core facing (ground) refractory
Metallurgical Silicon carbide, flux for metal smelting
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Blasting, scouring cleansers (ground), sawing and sanding, chemicals (ground
and
Abrasives
un- ground)
Fillers Rubber, paints, putty, whole grain fillers/building products
Ceramic Pottery, brick, tile, and refractory ceramics
Filtration Water (municipal, county, local), swimming pool, others
Petroleum
Hydraulic fracturing, well packing, and cementing
industry
Golf courses, baseball, volleyball, play sands, beaches, traction (engine),
roofing
Recreational
granules and fillers, other (ground silica or whole grain)
Gravel Silica, ferrosilicon, filtration, nonmetallurgical flux, other
Table 1: Typical uses of silica sand and gravel
[0013]. In March 2016, the Occupational Safety and Health Administration
(OSHA) issued a final
rule to requiring companies to control exposure to respirable crystalline
silica. The rule is comprised of
two standards: one for Construction (29 Code of Federal Regulations (CFR)
1926.1153) and the other
for General Industry (29 CFR 1910.1053) and Maritime (29 CFR 1915.1053). The
Maritime and General
Industry standards are the similar, but differ from the Construction standard.
The General
Industry/Maritime Standard requires the employer to perform air monitoring to
determine the eight-
hour average exposure level for each affected job task. Employers governed by
the Construction
standard can either use a control method spelled out for common construction
work tasks or perform
air monitoring as detailed in the General Industry/Maritime standard.
[0014]. These requirements can be expensive to implement. To use
crystalline silica in the
workplace, worker protective measures need to be taken. Initially, airborne
crystalline silica sampling
needs to be conducted. Once collected, the samples are sent to a laboratory
for analysis. The results
of this analysis will determine if improved ventilation and/or a change in
work practices or respiratory
protection is needed.
[0015]. The new action limit and permissible exposure limit (PEL) for
crystalline silica for
General Industry, Construction and Maritime are all the same and can be found
in Construction (29 CFR
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1926.1153), General Industry (29 CFR 1910.1053) or Maritime (29 CFR
1915.1053). The action limit is
established at 25 micrograms per cubic meter (ug/m3) and the PEL is
established at 50 ug/m3.
[0016]. To help control the risk of respirable crystalline silica exposure,
OSHA's "three lines of
defense" philosophy is suggested. The first line of defense is to eliminate
and/or engineer the
crystalline silica exposure hazard out. This may be best performed by removing
the crystalline silica
from the workplace. When engineering/elimination controls are not feasible or
practical, the second
and third lines of defense can be used to help control the crystalline silica
exposure hazard. The second
line of defense is administrative controls, and the last line of defense to be
considered is personal
protective equipment (PPE).
[0017]. OSHA recommends the first engineering control to consider is
substitution of the
crystalline silica with a nonhazardous product. OSHA suggests using a less
toxic abrasive blasting media
that can be delivered with water to reduce dust generation. This creates the
need for a suitable
substitution for the crystalline silica.
[0018]. The advantages of using a silica substitute outweigh using silica
in abrasive sandblasting
due to the hazards and compliance with the regulations. The health issues and
healthcare costs
related to silica would be greatly reduced or eliminated. The time and cost of
implementing and
maintaining engineering controls would also be eliminated. The disadvantages
are that the existing
substitutes may not be as hard as a crystalline silica abrasive, nor as dense.
Therefore, more of the
substitute may need to be used to achieve the same result. It may also be more
expensive.
[0019]. There is a need for a safe substitute for crystalline silica
products that do not cause
silicosis and do not require strict engineering controls for safe use. There
is a further need for an
inexpensive, effective amorphous silica sand and amorphous silica gravel for
commercial and
residential products, including for use as a blasting medium. There is a
further need for a water-
soluble amorphous silica product.
SUMMARY
[0020]. Embodiments of the method may be used to produce amorphous silica
materials
including, but not limited to, glass, container glass, fiber glass, glass
bead, sheet or plate glass, glass
aggregate, glass sand, abrasives, proppants, foamed glass, and manufactured
glass articles. The initial
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processing steps include preparing a melt batch comprising at least one silica
containing component
and other processing or product enhancing components, melting the melt batch,
and cooling the
melted melt batch. All batches described herein may be thermally processed by
melting, fusing or
sintering. Sintering or fusing of the components of the batch should be
performed sufficiently to
convert a significant amount of the crystalline silica into amorphous silica
such as below toxicity levels
for applications that will result in airborne dust. Further processing steps
may be utilized to produce
the glass product or article. These finishing processing steps are known in
the art and may be applied
as known in the art during the cooling step or in addition to the method. Such
steps are used to
produce the glass, container glass, fiber glass, glass bead, sheet or plate
glass, glass aggregate, glass
sand, abrasives, proppants, foamed glass, and manufactured glass articles.
Therefore, an embodiment
described herein to produce an abrasive particle may be modified to change
quenching and crushing
steps with a molding, air cooling or floating process as known in the art, for
example.
[0021]. Embodiments of the amorphous silica products comprise higher
concentrations of metal
oxides, such as, but not limited to, iron oxide, alumina, and zirconia, for
example. The concentrations
of metal oxides result in an amorphous silica product with a density and
hardness above the density
and hardness of typical recycled glass. The amorphous silica product may be
substantially free of
deleterious levels of toxic or heavy metals. As used herein, the term
"substantially free of deleterious
levels of toxic or heavy metals" means that the environmental and industrial
hygiene organizations do
not consider the amorphous silica product toxic if used as intended.
[0022]. An embodiment of an amorphous silica product for use as an
abrasives, proppants, and
sand/sanded products such as, but not limited to, grouts, mortars and
concrete, for example, may
comprise silicon oxide in the range of 56 wt.% to 80 wt.%, iron oxides in the
range of 5 wt.% to 35
wt.%, aluminum oxides in the range of 0 wt.% to 8 wt.%, zirconium oxides in
the range of 0 wt.% to 5
wt.%, and modifiers in the range of 0 wt.% to 10 wt.%.
[0023]. Embodiments of the amorphous silica products including the
abrasives, proppants, and
sand/sanded products may require the amorphous silica products to be ground to
particles. Therefore,
embodiments of the amorphous silica products are particles that have been
classified into particle size
ranges. The embodiments include particles that have a bulk composition
consisting essentially of
silicon oxide in the range of 56 wt.% to 80 wt.%, iron oxides in the range of
15 wt.% to 35 wt.%,
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aluminum oxides in the range of 0 wt.% to 8 wt.%, zirconium oxides in the
range of 0 wt.% to 5 wt.%,
and modifiers in the range of 0 wt.% to 10 wt.%.
[0024]. The oxides may comprise oxides in multiple forms or valences such
as ferric and ferrous
oxides. The glass batches may be melted comprising various forms of the metals
such as alloys, ores,
oxides or silicates, for example, but the amorphous silica product is reported
as oxides.
[0025]. The density of embodiments of certain embodiments of the amorphous
silica products
is correlated with increasing concentrations of metal oxides in the amorphous
silica products including
but not limited to, iron oxides, zirconium oxides, aluminum oxides, and
combinations thereof, for
example. Embodiments of the amorphous silicate products may have a density in
the range of 2.5 g/cc
to 3.5g/cc. Embodiments with higher concentrations of iron oxide and/or other
metal oxides may have
a density in the range of 2.8 g/cc to 3.5 g/cc.
[0026]. .. An embodiment of an amorphous silica product for use as abrasives,
proppants, and
sand/sanded products such as, but not limited to, grouts, mortars and
concrete, for example, may
comprise silicon oxide in the range of 56 wt.% to 80 wt.%, iron oxides in the
range of 10 wt.% to 45
wt.%, aluminum oxides in the range of 0 wt.% to 8 wt.%, zirconium oxides in
the range of 0 wt.% to 5
wt.%, and modifiers in the range of 0 wt.% to 10 wt.%. The modifier may be
typical fluxes used in glass
manufacturing, for example. The embodiments of the amorphous silica product
for use as abrasives,
proppants, and sand/sanded products may be crushed and classified into
particle size ranges.
Abrasives, proppants and sands/sanded products are typically classified into
different particle size
ranges based upon the intended application.
[0027]. Further, the hardness of embodiments of the amorphous silica
product is correlated
with increasing iron oxides, zirconium oxides, aluminum oxides, calcium
oxides, and combinations
thereof. Embodiments of the amorphous silicate product have a Knoop hardness
in the range of 520
Hk to 800 Hk. Embodiments with higher concentrations of the metal oxides may
have a Knoop
hardness in the range of 750 Hk to 850 Hk.
[0028]. Certain embodiments of the method comprise converting sand, gravel,
other minerals
and rock naturally comprise converting crystalline or polycrystalline silica
(hereinafter, "crystalline
silica") to an amorphous glass sand or gravel. For example, the crystalline
silica sand, gravel, other
particles, and/or mineral include, but are not limited to, silica sand, silica
gravel, quartz sand, any type
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of heavy mineral sand including garnet, staurolite, and olivine, for example.
The amorphous glass sand
or gravel may be used in or converted to the commercial and residential
applications as described
herein.
[0029]. .. Embodiments of the method of producing amorphous silica sand or
other products
comprises converting material comprising crystalline silica into an amorphous
glass sand, gravel, or
other amorphous product. The conversion may be performed by heating the
crystalline silica to a
temperature above the temperature that results in the phase change to an
amorphous form of silica.
In certain embodiments, this temperature may be above the melting temperature
of crystalline silica.
The melting point of pure silica dioxide is approximately 3110 F (1710 C). The
melting point may vary
based upon the natural composition of the sand, gravel or other rock.
[0030]. As stated, the melting point of pure silica dioxide is high
relative to other materials and
processing may be difficult. The melting point of a glass batch comprising
crystalline silicas may be,
and typically is, lowered by addition of melting temperature reducing agents
(fluxes). Thus, in other
embodiments, a glass batch may be prepared by mixing the crystalline silica
with a melting point
reducing agent.
[0031]. .. Further, the density of pure amorphous silica may be too low for
some applications,
such as for an effective abrasive blasting medium. Abrasive blasting media may
generally be classified
by their specific gravity and hardness. Some properties of the media will
affect the efficiency of
abrasives in removing coatings or cleaning surfaces including hardness and
density, for example.
Generally, the greater the difference in hardness between the abrasive media
and the coating to be
removed or material to be cleaned, the more efficient the blasting process.
Higher density particles
may also result in a more efficient blasting process because higher density
particles with similar
contact velocity as lower density particles of approximately the same size
will generally have a greater
contact force and, therefore, result in a more efficient stripping or cleaning
process.
[0032]. .. Additionally, a method of producing a water-soluble amorphous
silica sand, gravel, or
other particles may comprise mixing at least one flux with the crystalline
silica dioxide containing
material. Embodiments of the method may comprise mixing a flux or fluxes with
the silica dioxide
containing material wherein at least one of the flux or fluxes mix with the
silica dioxide containing
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material to increase at least one of the density and the hardness of the
resulting amorphous silica
product relative to pure amorphous silica or container glass.
[0033]. Metals, and metal oxides may be used as fluxes for crystalline
silica dioxide that would
result in an amorphous glass product with increased density and/or increased
hardness. More
conventional glass fluxes may also be added such as, but not limited to, soda
ash and potash.
[0034]. Embodiments include abrasive blasting media and methods of
producing abrasive
blasting media. Embodiments of the method for producing amorphous silica
abrasive blasting
materials eliminate the step of collecting, cleaning, and classifying recycled
or waste glass. As such,
embodiments of the process comprise transforming crystalline or
polycrystalline sand, gravel, other
particles, or rock that comprise crystalline silica into amorphous sand,
gravel, other particles, or rock to
reduce the concentration of crystalline silica (a known carcinogen) to safer
levels when the amorphous
silica sand, gravel or other particle is manufactured or used. Thus,
embodiments of the method
comprise making these products into a more industrial hygiene friendly
substitution for naturally
occurring products containing various forms of crystalline silica.
[0035]. In another embodiment, the process for producing amorphous products
consists
essentially of heating sand and/or a mineral comprising crystalline silica
into an amorphous mass,
cooling the amorphous mass to a solid, and forming particles comprising
amorphous silica. The
particles of amorphous silica may be further crushed or otherwise comminuted
to reduce the size of
the particles or produce particles having a narrower particle size
distribution, for example.
[0036]. An embodiment of the amorphous silica product or abrasive blasting
media comprises
silicon oxide in the range of 50 wt. % to 75 wt. %, metals or metal oxides in
the range of 20 wt.% to 45
wt.%, and other fluxing compounds in the range of 0 to 10 wt. %. In some
embodiments, the other flux
compounds or fluxing compounds do not include the metal oxides. The metal
oxides include, but are
not limited to, iron oxides, aluminum oxides, zirconium oxides, titanium
oxides, manganese oxides,
magnesium oxides, and combinations thereof. The metal oxides may be added from
clays, rock,
and/or minerals containing silicates, oxides, or other forms of these metals.
[0037]. Metals may also be added in their pure metal form or as an alloy.
The metals include,
but are not limited to, iron, aluminum, titanium, zirconium, manganese,
magnesium, alloys and
combinations thereof. The metals may be melted in a furnace in the presence of
oxygen (air) to at
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least partially form oxides or in a furnace with an inert atmosphere to melt
directly into the amorphous
silica.
[0038]. For example, an embodiment of the amorphous silica product or
abrasive blasting
media comprises silicon oxide in the range of 50 wt. % to 75 wt. %, iron
oxides in the range of 15 wt.%
to 45 wt.%, and other fluxing compounds in the range of 0 to 10 wt. %. To
reduce the melting point,
the other fluxes may be in the range of 1 wt.% to 10 wt.%. This embodiment of
the amorphous silica
product may comprise either aluminum oxides in the range of 0.5 wt.% to 10 wt.
%, zirconium oxides in
the range of 0.5 wt.% to 10 wt. %, or a combination thereof.
[0039]. The fluxing compounds may include any fluxes typically used in
glass manufacturing and
may include, but are not limited to, those that result in sodium oxides,
calcium oxides, magnesium
oxides, potassium oxides, lithium oxides, boric oxides, and combinations
thereof in the glass.
[0040]. In some embodiments, the amorphous silica product or abrasive
blasting media may
comprise a ratio of Si to Fe in the amorphous silica product or abrasive
blasting media is in the range of
3:4 to 4:1. Other embodiments, the ratio of Si to Fe in the range of 3:4 to
3:1. In other embodiments,
the amorphous silica product may comprise a ratio of Si to the total of Fe and
Al in the range of 3:4 to
3:1. In another embodiments, the amorphous silica product may comprise a ratio
of Si to the total of
Fe and Zr in the range of 3:4 to 3:1. In another embodiments, the amorphous
silica product may
comprise a ratio of Si to the total of Fe, Zr, and Al in the range of 3:4 to
3:1.
[0041]. In a still further embodiment of the amorphous silica product or
abrasive blasting media
comprises silicon oxide in the range of 50 wt. % to 75 wt. %, iron oxides in
the range of 25 wt.% to 55
wt.%, and other fluxing compounds in the range of 0 to 10 wt. %. To further
reduce the melting point,
the other fluxes may be in the range of 1 wt.% to 10 wt.%. This embodiment of
the amorphous silica
product may comprise aluminum oxides in the range of 0.5 wt.% to 10 wt. %,
zirconium oxides in the
range of 0.5 wt.% to 10 wt. %, or a combination thereof to produce the desired
properties.
[0042]. In another embodiment of the amorphous silica product or abrasive
blasting media
comprises silicon oxide in the range of 50 wt. % to 75 wt. %, a combination of
iron oxides and one of
aluminum oxides, zirconium oxides, or a combination of aluminum oxides and
zirconium oxides in the
range of 25 wt.% to 60 wt.%, and other fluxing compounds in the range of 0 to
15 wt. %. To further
reduce the melting point, the other fluxes may be in the range of 1 wt.% to 15
wt.%.
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[0043]. Another embodiment is directed to an amorphous silica product or an
abrasive blasting
media consisting essentially of silicon oxide in the range of 50 wt. % to 75
wt. %, iron oxides in the
range of 20 wt.% to 40 wt.%; and fluxing compounds in the range of 0 to 15 wt.
%.
[0044]. Embodiments of the method are directed to a method of producing a
glass product
comprising preparing a melt batch, wherein the melt batch comprises silicon
oxide in the range of 55
wt. % to 75 wt. %, at least one of iron, iron silicates, and iron oxides in
the range of 18 wt.% to 45 wt.%,
and flux or fluxes in the range of 0 wt.% to 20 wt.%. The melt batch is heated
to melt the components
a glass melt and cooling the glass melt. Cooling the glass melt may comprise
quenching the glass melt,
air cooling the glass melt, annealing the glass melt or combinations thereof.
[0045]. In any embodiment, the melt batch consists essentially of silicon
oxide in the range of 55
wt. % to 75 wt. %, at least one of iron, iron silicates, and iron oxides in
the range of 18 wt.% to 45 wt.%,
and other flux components in the range of 0.5 wt.% to 10 wt.%.
[0046]. A still other embodiment of the amorphous silica product or the
abrasive blasting media
comprises silicon oxide in the range of 45 wt. % to 75 wt. %, iron oxides in
the range of 25 wt.% to 45
wt.%, and fluxing compounds in the range of 0 to 10 wt. %. In some
embodiments, the amorphous
silica product or abrasive blasting media consists essentially of silicon
oxide in the range of 45 wt. % to
75 wt. %, iron oxides in the range of 28 wt.% to 45 wt.%, and fluxing
compounds in the range of 0 to 10
wt. %.
[0047]. An abrasive blasting media comprising or, in some cases consisting
essentially of, silicon
oxide in the range of 50 wt. % to 75 wt. %, iron oxides and aluminum oxides,
wherein the iron oxides
and the aluminum oxides together are in in the range of 5 wt.% to 50 wt.%, and
fluxing compounds in
the range of 0 to 10 wt. %. For this embodiment, the abrasive blasting media
may comprise the
aluminum oxides in the range of 3 to 10 wt.%.
[0048]. An abrasive blasting media comprising or, in some cases consisting
essentially of, silicon
oxide in the range of 50 wt. % to 75 wt. %, iron oxides and aluminum oxides,
wherein the iron oxides
and the aluminum oxides together are in in the range of 25 wt.% to 50 wt.%,
and fluxing compounds in
the range of 0 to 10 wt. %. Also, for this embodiment, the abrasive blasting
media may comprise the
aluminum oxides in the range of 3 to 10 wt.%.
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[0049]. The amorphous silica product or the abrasive blasting media may
comprise, or consist
essentially of, silicon oxide in the range of 50 wt. % to 75 wt. %, iron
oxides and zirconium oxides,
wherein the iron oxides and the zirconium oxides together are in in the range
of 12 wt.% to 50 wt.%,
and fluxing compounds in the range of 0 to 10 wt. %. For this embodiment, the
zirconium oxides are in
the range of 2 to 10 wt.%.
[0050]. The amorphous silica product or the abrasive blasting media may
comprise, or consist
essentially of, silicon oxide in the range of 50 wt. % to 75 wt. %, iron
oxides and zirconium oxides,
wherein the iron oxides and the zirconium oxides together are in in the range
of 25 wt.% to 50 wt.%,
and fluxing compounds in the range of 0 to 10 wt. %. For this embodiment, the
zirconium oxides are in
the range of 2 to 14 wt.%.
[0051]. In a still other embodiment, an amorphous silica product or
abrasive blasting media
consists essentially of silicon oxide in the range of 50 wt. % to 75 wt. %,
iron oxides in the range of 20
wt.% to 45 wt.%, and fluxing compounds in the range of 4 to 20 wt. %.
[0052]. Embodiments also include methods of producing an amorphous silica
product or
abrasive media. The method may comprise preparing a melt composition. Melt
compositions of
various compositions may be prepared. One embodiment of the melt composition
comprises 50 wt.%
to 75 wt.% of silicon oxides, 12 wt.% to 40 wt.% of iron oxide, and 4 wt.% to
20 wt.% of at least one flux
component. The melt composition may be referred to as a "glass batch." The
term "glass batch" may
refer to the raw materials fed into a batch furnace or a continuous furnace.
[0053]. Another embodiment of the melt composition comprises 50 wt.% to 75
wt.% of silica, 12
wt.% to 40 wt.% of iron containing material, 4 wt.% to 20 wt.% of at least one
flux component. In
embodiments, the iron containing material may be at least one of iron oxides,
iron silicates, iron filings,
or iron containing minerals. In such embodiments, the melt composition
comprises 50 wt.% to 75
wt.% of silicon oxide, 10 wt.% to 40 wt.% of iron containing metal filings,
and 4 wt.% to 20 wt.% of at
least one flux component.
[0054]. In some embodiments, the melt composition comprises or consists
essentially of 40
wt.% to 80 wt.% of cullet and 8 wt.% to 60 wt.% of at least one metal oxide.
In these embodiments,
the metal oxide may be at least one of iron oxide, aluminum oxide, zirconium
oxide, titanium oxide,
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magnesium oxide. The metal oxides may be added individually, in alloys, or
minerals comprising these
metal oxides. As used herein, the term "cullet" includes both process cullet
and postconsumer cullet.
[0055]. Further embodiments of the method of forming an amorphous silica
product or abrasive
comprise preparing a melt composition, wherein the melt composition comprises
50 wt.% to 75 wt.%
of silica, 12 wt.% to 40 wt.% of a mix of metal oxides, and 2 wt.% to 20 wt.%
of at least one flux
component. In this embodiment, the silica may be amorphous silica (cullet,
obsidian) or crystalline
silica.
[0056]. The methods may further comprise other glass manufacturing or frit
manufacturing
process steps, such as, but not limited to, melting the melt composition in a
furnace to form a melt,
cooling the melt to form a solid product, crushing or otherwise comminuting
the amorphous product
to form particles and/or classifying the particles into particle size ranges.
[0057]. In any embodiment, the silicon oxides may include amorphous or
crystalline silicon
oxides in the melt composition. The silicon oxides may be cullet, sand, stone,
gravel, or other silica
containing minerals, for example.
[0058]. The basic and novel features of the invention are to prepare an
amorphous silica
product or abrasive blasting media that does not comprise significant
concentration of crystalline silica
or other toxic compounds for use in industrial, commercial, or residential
applications.
[0059]. In some embodiments, the amorphous silica product may comprise
significant amounts
of deleterious toxic compounds or heavy metals if they do not cause industrial
hygiene problems
during manufacture, transport or use.
[0060]. In another embodiment, the process for producing amorphous products
consists
essentially of heating sand and/or a mineral comprising crystalline silica
into at least one amorphous
mass, cooling or allowing the amorphous mass to cool, crushing or otherwise
comminuting the size of
the amorphous mass into gravel, sand, or silt sized particles, and classifying
the sand, gravel, or silt
sized particles into a desired particle size distribution for use as an
abrasive blasting media or in other
products.
[0061]. In another embodiment, the process for producing amorphous products
consists
essentially of heating sand and/or a mineral comprising crystalline silica to
a temperature between the
melting temperature and less than the gob temperature of the glass batch,
quenching, cooling or
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allowing the amorphous mass to cool, reducing the size of into gravel, sand,
or silt sized particles, and
grading the gravel, sand, or silt sized particles into a desired particle size
distribution for use as an
abrasive blasting media or in other products.
[0062]. Embodiments of the method of the present invention may not require
the post melt
processing steps of glass making such as forming and floating, for example.
[0063]. As such, embodiments of the method comprise preparing a glass batch
comprising
crystalline silica, heating the glass batch or melt composition to produce a
molten amorphous mass in
a furnace, cooling the furnace effluent such as by quenching the amorphous
mass in a water bath or
spray to produce amorphous silica mass or particles, optionally, further
crushing the amorphous silica
particles, and, optionally, annealing the amorphous silica particles.
[0064]. The iron oxides or iron silicates, aluminum oxide or silicates,
and/or the zirconium
oxides or silicates, for example, may be added to the melt composition or
glass batch in the form of
various sources including clays and minerals.
[0065]. The "amorphous sand" or other amorphous silica product could be
formed directly into
particles by fritting, for example, or formed into larger masses and crushed
depending on the preferred
method to obtain a commercially viable and advantageous product for various
applications.
[0066]. In certain embodiments, the properties of amorphous silica or sand
may be improved
for a specific application such as for use as a blasting media. Currently,
there is no tailoring of recycled
glass for blasting at this time. Since current amorphous silica blasting media
was originally produced
for a different purpose (container or plate glass), the properties have not
been tailored as a blasting
media. The amorphous silica blasting media could have the following
properties, for example, if
possible:
[0067]. 1) Specific gravity higher than crushed glass, for example, over
2.6 (crushed glass is
approximately 2.5, crystalline silica sand is approximately 2.6); and 2)
Hardness (mohs scale)
approaching 7.0 to 7.5 (crushed glass is 5.5 to 7, crystalline silica sand is
approximately 5 to 6) or a
Knoop hardness above 520 or in certain embodiments above 680, for example.
[0068]. At least one embodiment of the blasting media will be water
soluble, so stabilizers such
as calcium oxide, for example, are not required in certain embodiments as are
typically added to the
production of container glass and plate glass.
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[0069]. Typical particle sizes for blasting abrasives are in the range of
mesh size 20/30, 30/70,
and 50/100, for example. These mesh sizes may, typically, include 10% of the
particles above or below
the stated mesh size range.
[0070]. Proppants may also be used and sold in various particle size
ranges. The typically
coarsest standard product for proppant is 20/40. (20/40 particle size means
that 90 percent of the
proppant product is small enough to pass through the 20 mesh screen having an
opening of 0.85 mm)
and large enough for greater than 90% of the particles to be retained on the
40 mesh screen (0.425
mm). Each product allows for a distribution of grain sizes within the range.
Other standard proppant
sizes are 30/50, 40/70, and 50/140 and are similarly defined. Embodiments of
the proppants have
particle sizes in the range of 20 to 140 mesh, further embodiments, include
proppants having particles
in the following particle size ranges 20/40, 30/50, 40/70, and 50/140.
Further, embodiments of the
method comprise melting the glass batch, crushing the amorphous solid, and
classifying the particles in
particle size range appropriate for use as a proppant. The particle size
ranges appropriate for use as a
proppant include, but are not limited to, 20/24, 30/50, 40/70, and 50/140, for
example.
[0071]. In further embodiments, appearance and opacity would not matter as
much as in a
blasting material as in container or plate glass. Embodiments of the amorphous
silica products may
not have any transparency or clarity restrictions. Constituents added to the
batch to reach these
properties may make the glass opaque, ugly or unable to be formed by
traditional glass methods, for
example.
[0072]. Embodiments of the amorphous silica products should have no
significant amounts of
toxic components at sufficient quantities that would create inhalation hazards
if used where human
contact or inhalation is expected. Blasting media comprising iron oxides have
shown low toxicity in
testing. In contrast to the other abrasive blasting agents, for example, the
major component of
specular hematite is iron oxide and specular hematite produced no significant
alterations in BAL levels
of LDH, numbers of lung PMN, macrophage chemiluminescence, the amount of
pulmonary
hydroxyproline, or fibrotic score. (Barnes Environmental, Inc., 1996). These
findings are consistent
with the low toxicity of iron oxide in most rat studies (Stokinger, 1984). A
recent study in humans also
suggests that the initial inflammation associated with intrapulmonary
instillation of iron oxide resolves
rapidly after exposure (Lay et al., 1999).
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[0073]. The glass batch and/or crystalline silica sand or rock need only be
converted to an
amorphous silica, not fully melted. The cooling and crushing processes may be
designed for economy,
to deliver the desired properties, and to provide ease with the production of
sand sized particles in the
desired particle size ranges. Embodiments of the process to produce amorphous
glass products may
be summarized as an efficient method of producing crushed, recycled glass
particles with higher
density and improved hardness directly from crystalline silica materials for
the same cost as recycle
glass or from cullet to enhance the properties for specific applications.
[0074]. The production of a relatively high iron amorphous mineraloid can
be performed
without more rigorous processes such as found in the production of soda lime
glass. Embodiments of
the method of forming the amorphous silica product may not require
fining/viscosity reduction or
annealing of container or flat glass.
[0075]. As stated, the method may further comprise melting glass cullet in
combination with
property enhancing components. The property enhancing components may comprise
iron oxides, iron
silicates, iron, aluminum oxide, aluminum silicates, aluminum, zirconium
oxide, zirconium silicates
and/or other materials comprising zirconium to produce an enhanced amorphous
silica product. The
property enhancing components may provide an amorphous silica product with
higher hardness
and/or higher density that typical recycled glass or glass cullet.
[0076]. In a typical glass process, the silica does not melt but is
solubilized in the flux such as the
melted sodium carbonate. Embodiments of the process include replacing at least
a portion of the
calcium oxide (or calcium carbonate) and the sodium carbonate in container
glass with iron, aluminum
or similar materials as fluxes. The iron can come from clays or iron oxides
and the aluminum can come
from aluminum oxide which is abundant and cheap. There are aluminum silicates
that also include iron
that may be added.
[0077]. Embodiments of the method do not comprise or can eliminate the
fining process step of
container glass making and, further, may not need to completely melt the
components as iron or other
particles, bubbles, etc. are not detrimental to the product. Frit furnaces do
not include a fining
process, for example.
[0078]. Embodiments of the invention change soda lime glass composition by
changing fluxes to
enhance density and hardness. Replacing sodium carbonate and calcium carbonate
with oxides of iron
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and alumina, both of which make excellent fluxes, should make a glass oxide
product that exhibits
higher density and/or hardness than ordinary soda lime glass.
[0079]. The glass batch and amorphous silica products are defined by their
components.
However, zirconia (zirconium oxide) may be replaced with zirconia silicate,
for example, on a zirconia
equivalent substitution. The same molar amount of zirconium silicate may be
added to the glass batch
or be present in the amorphous silica product to maintain the weight
percentage of zirconium.
Similarly, aluminum oxide may be substituted for alumina silicate and iron
silicate may be substituted
for iron oxide.
[0080]. Components that may be added that do not materially affect the
basic and novel
characteristics of the claimed invention include, but are not limited to, do
not materially affect the
basic and novel characteristic(s)" of the claimed invention. The secondary,
additive materials may
include colorants, decolorants, fining agents, oxidizers, reducers, or any
other additive that does not
contribute to the main oxide content of the glass.
[0081]. Unless otherwise defined, all terms (including technical and
scientific terms) used herein
have the same meaning as commonly understood by one having ordinary skill in
the art to which this
invention belongs. It will be further understood that terms, such as those
defined in commonly used
dictionaries, should be interpreted as having a meaning that is consistent
with their meaning in the
context of the relevant art and the present disclosure and will not be
interpreted in an idealized or
overly formal sense unless expressly so defined herein.
[0082]. In describing the invention, it will be understood that a number of
components, parts,
techniques and steps are disclosed. Each of these has individual benefit and
each can also be used in
conjunction with one or more, or in some cases, all of the other disclosed
embodiments and
techniques. Accordingly, for the sake of clarity, this description will
refrain from repeating every
possible combination of the individual steps in an unnecessary fashion.
Nevertheless, the specification
and claims should be read with the understanding that such combinations are
entirely within the scope
of the invention and the claims.
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DESCRIPTION
[0083]. Embodiments of the invention include abrasive blasting media,
proppants, and other
amorphous silica products. The other amorphous silica products include, but
are not limited to,
amorphous silica sands, gravels, or other particles, containers, sheets, or
fibers, beads, spheres, and
manufactured articles. The abrasive blasting media, proppants, and amorphous
silica products may
comprise amorphous silica and other components that result in products with
properties that are
beneficial for the intended application or to improve the processing of the
material.
[0084]. An embodiment of the method comprises heating granules, grains, or
particles of sand,
minerals, or rock comprising crystalline silica (hereinafter, "crystalline
silica") to a temperature where
the crystalline silica loses its crystalline structure and is transformed into
an amorphous silica or
amorphous silicate. The amorphous silica is then cooled at a sufficient rate
to prevent recrystallization
and, therefore, produce an amorphous silica or silicate sand, gravel, or other
particle, sheets, or fibers,
beads, spheres, and manufactured articles.
[0085]. .. Embodiments of the method comprise heating any type of sand or
mineral comprising
crystalline silica to a temperature in which the crystalline silica converts
to amorphous silica form. The
crystalline silica may be mixed with other components prior to or during the
melting process such as,
but not limited to, at least one of melting point reducing agents (fluxes),
formers, stabilizers, density
increasing components, hardness increasing components, toughness increasing
components, or
combinations thereof.
[0086]. Another embodiment of the invention comprises adding additional
components to an
amorphous silica product, such as glass or cullet, to form a glass batch and
melting the glass batch to
incorporate the additional components into the amorphous silica. The
additional components include,
but are not limited to, at least one of a material comprising crystalline
silica, melting point reducing
agents (fluxes), formers, stabilizers, density increasing components, hardness
increasing components,
toughness increasing components, or combinations thereof. In one embodiment,
the method
comprises mixing recycled glass (cullet) to the crystalline silica sand or
mineral and additional
components to form the glass batch and melting the glass batch.
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[0087]. Embodiments of a method of producing an abrasive particle comprise
melting a glass forming
material with property improving components. Some of the property improving
components include, but are
not limited to, metals, metal oxides, metal silicates, fluxes, metal ores,
sources of these components, and
combinations thereof. These sources of the property improving components
include, but are not limited to,
ores such as, magnetite, lodestone, taconite, iron ores and products produced
from iron ore, other minerals
such as, but not limited to, limestone, garnet, furnace slags including, but
not limited to, coal slags, iron slags,
copper slags, nickel slags and other metal slags.
[0088]. The metal oxides include iron oxides, FeO, Fe02, mixed oxides
Fe(II, Ill), Fe304, Fe(III), and
Fe2O3, aluminum oxides, zirconium oxides, intermediate glass forming oxides
such as, but not limited to,
alumina, zirconia, titania, ferric iron, glass modifier oxides such as, but
not limited to, oxides of calcium,
magnesium, zinc, ferrous iron, alkali metals and other glass forming oxides,
intermediate glass forming oxides
and glass modifier oxides apparent to a person skilled in the art are
considered to be within the scope of the
present invention. One particular source of iron oxide that may be used in
embodiments of the invention is
magnetite and Fe(II, Ill). Therefore, in one embodiment, the metal oxides may
consist essentially of magnetite.
In such embodiments, the magnetite may be added to the batch in concentration
of 15 wt.% to 40 wt.% alone or
in combination with other metal oxides. The source of the iron oxides may be
iron ore.
[0089]. The embodiments below are exemplified primarily with iron oxides,
however, the iron oxides
may be replaced with at least one of at least one of a metal oxide, a metal
silicate, a metal, a metal silicide, or
combination thereof. For example, the iron oxides may be replaced with a
metal, metal oxides, or metal
silicates including, but not limited to, be iron, iron oxides, iron silicates,
aluminum oxides, aluminum silicates,
aluminum, zirconium oxides, zirconium silicates, or zirconium, titanium
oxides, combinations thereof, or ores or
other sources containing these components.
[0090]. Silicate glass precursors include raw materials such as, but not
limited to, silica sand, glass cullet,
recycled glass, siliceous materials and minerals, alumina, alumina silicate
materials, boron oxide, borosilicates,
calcium carbonates, calcium silicates, aluminates, alumina bearing materials,
lime, and magnesium bearing
materials, limestone, dolomite, and alkaline oxide bearing compounds and
minerals such as phosphates,
carbonates and hydroxides of alkali metals. The above list may not be
exhaustive and any other materials
apparent for the person skilled in the art are considered to be included
within the scope of the present
invention. For example, the limestone in the embodiments as described herein
that is added to cullet, silica
sand, concrete sand, or combination thereof may be substituted by or mixed
with dolomite, sea shells, oyster
shells, chalk, calcite, aragonite, glendonite, ikaite, calcium carbonate,
amorphous calcium carbonate, synthetic
calcium carbonate, or combinations thereof in the same concentration ranges.
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[0091]. Various embodiments of the methods produce abrasives, proppants or
other products
(amorphous silica particles) having a density greater than 2.5 g/ml or between
2.5g/m1 and 4.0 g/ml. In other
embodiments, the abrasives, proppants or other products having a density
between 2.5 g/ml and 3.5 g/ml.
Further embodiments of the methods produce the amorphous silica particles have
a density greater than 2.65
g/ml and 3.6 g/ml; a density greater than 2.80 g/ml and less than 4.0 g/ml;
and amorphous silica particles have a
density greater than 3.0 g/ml and less than 4.0 g/ml. Various applications of
the particles may have different
desired densities. The density of the particles may be tailored as desired by
modifying the composition of the
glass, the process parameters, or the post-production heat and pressure
treatment, for example.
CULLET 50 ¨ 75 / iron oxide
[0092]. Batches may be based upon melting amorphous silica products with
property enhancing
components. For example, embodiments of the method of producing an abrasive
particle may comprise
preparing a batch comprising glass cullet in a concentration range of 50 wt.%
to 75 wt.%; iron oxide in a
concentration range of 20 wt.% to 40 wt.%; and fluxes in a concentration range
of 5 wt.% to 40 wt.%. In any
embodiment, the batch may be fed into a batch furnace or a continuous furnace.
The batch materials may be
premixed and fed into the furnace, fed individually or some components may be
premixed, and some may be
fed into the furnace individually. In a further embodiment, preparing a batch
may consist essentially of glass
cullet in a concentration range of 50 wt.% to 75 wt.%; iron oxide in a
concentration range of 20 wt.% to 40 wt.%;
and fluxes in a concentration range of 5 wt.% to 40 wt.%.
[0093]. The batch may be melted in a furnace to produce furnace effluent or
melt effluent. Typically,
the batch components will be fed into the furnace as solids and flow out as a
molten liquid. The melt effluent is,
typically, a liquid melted glass that flows from the furnace exit. The melt
effluent may be cooled to form a solid
amorphous glass by any known means. The cooling means may include, but is not
limited to, water quenching,
oil quenching, air cooling, annealing, and controlled air cooling. Therefore,
in any embodiment, a quenching
step may be replaced with any other cooling step as described herein or known
in the art. The glass effluent is
merely cooled to form a solid. This may include floating or molding of the
glass.
[0094]. In one embodiment, the method comprises quenching the melt effluent
to form amorphous
silica particles or amorphous silica mass. The quenching may be performed by
directing the furnace effluent
into a water bath as known in the art.
[0095]. For some applications, it may be desirable to have the amorphous
silica particles or amorphous
silica mass in different particle sizes. The method may further comprise
crushing the amorphous silica particles
to form particles of the appropriate size for the desired application by
methods known in the art.
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[0096]. Additionally, The glass may undergo further densification process
such as, but not limited to,
heat treatments, cold compression, or hot compression. The densification may
occur after quenching or after
crushing the particles to the desired particle size range, particle size
average or other distribution. Silica glasses
may undergo reversible and irreversible amorphous-amorphous transitions under
pressure, leading to some
elastic softening upon initial compression and permanent densification under
high pressure. At room
temperatures (cold-compression), at pressures above 8-9 GPa, irreversible
polyamorphic transition takes place
and the recovered glass has an increased density. The same or even higher
amount of densification can be
achieved under much lower pressures (4-8 GPa) at high temperatures (hot-
compression). Under hot or cold
compression, the silica glass may densify up to about 25%.
[0097]. In some embodiments, the method may comprise adding a combustible
material to any of the
batches described herein. The combustible material may be any combustible
material that undergo combustion
at a temperature below the melt temperature of the batch or the processing
temperature. For example,
combustible materials include organic matter, cellulosic material, plastics,
paper, cloth, natural gas, oils, wood,
charcoal, coke, coal, fuels, and combinations thereof.
[0098]. The combustible material may be added separately or in combination
with other components of
the batch. For example, charcoal or coke particles or powders may be premixed
in the batch with the other
components or be present in one of the components of the batch. For example,
recycled glass products may
comprise combustible materials such as, but not limited to, paper, plastics,
cardboard, oils, food residues, for
example, and may, therefore, may be added to the batch with the recycled
glass.
[0099]. The combustible material may be added to the batch in any desired
concentration range, for
example, the combustible material may be in a concentration range of above 0
wt.% to 25 wt.%. The
combustible material in the batch appears to act to increase the density of
the amorphous silica particles. In
other embodiments, the combustible material may be added to the batch in a
concentration range of above 0.2
wt.% to 20 wt.%. In still further embodiments, the combustible material may be
added to the batch in a
concentration range of above 0.2 wt.% to 15 wt.%. In more specific
embodiments, the combustible material
may be added to the batch in a concentration range of above 0.5 wt.% to 8
wt.%.
[0100]. Limestone and its substitutes have been shown to increase the
density of some embodiments of
the amorphous silica products. Limestone additions to the batch have also
resulted in other improved
properties of the amorphous silica particles. Embodiments of the batch
comprise limestone in concentration of
1 wt.% to 50 wt.%. In further embodiments, the limestone may be added to the
batch in a concentration of 10
wt.% to 40 wt.%. In some embodiments, the batch may benefit from high
concentrations of limestone, thus in
such embodiments, the limestone may be incorporated in the batch in a
concentration of 25 wt.% to 40 wt.%.
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Limestone may be substituted with other sources of calcium equivalent
concentrations of calcium carbonate or
calcium oxides as described. In a particularly interesting embodiment, the
batch comprises limestone in a
concentration range of 25 wt.% to 40 wt.% and iron oxide, iron ore, or a
combination thereof in a concentration
range of 25 wt.% to 40 wt.%. The remainder of the batch includes cullet, sand
and a combination of fluxes.
[0101]. In a particular embodiment, the batch consists essentially of
cullet in a concentration range of
15 wt.% to 30 wt.%; limestone in a concentration range of 25 wt.% to 40 wt.%;
iron oxide, iron ore, or a
combination thereof in a concentration range of 25 wt.% to 40 wt.% and fluxes
in a range of 0 wt. % to 15 wt.%.
Such embodiments of the batch after melting and cooling may produce amorphous
silica particles have a density
greater than 2.65 g/ml and 3.6 g/ml and in some embodiments, a density greater
than 2.80 g/ml and less than
4.0 g/ml. In embodiments wherein the batch consists essentially of cullet in a
concentration range of 15 wt.% to
30 wt.%; limestone in a concentration range of 30 wt.% to 40 wt.%; iron oxide,
iron ore, or a combination
thereof in a concentration range of 30 wt.% to 40 wt.% and fluxes in a range
of 0 wt. % to 15 wt.%, the
amorphous silica particles produces after melting and cooling may have a
density greater than 3.0 g/ml and less
than 4.0 g/ml.
[0102]. .. Additionally, iron ores may be added to the batch as a source of
iron compounds to produce the
amorphous silica products. In a particular embodiment, a method of producing
an abrasive particle from iron
ore, the method comprises preparing a batch comprising of glass cullet in a
concentration of 50 wt.% to 70 wt.%,
iron ore in a concentration of 20 wt.% to 60 wt.%, and fluxes in a
concentration of 5 wt.% to 40 wt.%. The batch
may be melted to form a melt effluent and then be cooled to form an amorphous
silica particle. Additionally, the
method of producing an abrasive particle from iron ore, the method consists
essentially of preparing a batch
comprising of glass cullet in a concentration of 50 wt.% to 70 wt.%, iron ore
in a concentration of 20 wt.% to 60
wt.%, and fluxes in a concentration of 5 wt.% to 40 wt.%. The iron ore in the
batch may comprise taconite,
wherein the taconite in a concentration of 20 wt.% to 35 wt.%. In other
embodiments, the iron ore may consist
essentially of taconite.
[0103]. In some cases, other metal ores may be added into the glass batch
with either
crystalline silica, amorphous silica or a combination thereof. Ores such as,
but not limited to, iron ore,
taconite, or bauxite may be added, for example. The addition of bauxite to the
glass batch may
comprise adding a combination of the crystalline silica, iron oxides, and
additional metal oxides such as
aluminum oxide with the one component.
[0104]. The addition of the combustible material may further improve the
properties of the amorphous
silica particles. The mechanism is not fully understood at this time but the
results have been confirmed by
significant experimentation. Any of the embodiments described herein may also
comprise a combustible
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material in the batch in any concentration capable of improving the properties
of the amorphous silica
production. For example, a method of producing an abrasive particle comprising
preparing a batch comprising
glass cullet in a concentration range of 50 wt.% to 75 wt.%, iron oxide in a
concentration range of 20 wt.% to 40
wt.%, and a combustible material that ignites at a temperature less than the
melt temperature of the batch in a
concentration range of 0.5 wt.% to 25 wt.%. The method may further comprise
melting the batch in a furnace to
melt effluent, quenching the melt effluent to form amorphous silica particles
or mass, and crushing the
amorphous silica particles or mass to form abrasive particles. The combustible
materials may be any material
that may be intermixed with the other components of the batch. Examples have
been previously described.
[0105]. A further embodiment includes a batch that comprises a combustible
material and limestone.
The combination of a combustible material and limestone appears to provide a
synergism that results in a higher
density amorphous silica product than either component alone. For example, the
batch may comprise
combustible materials in the concentration range of 0.5 wt.% to 25 wt.%. and
limestone in a concentration
range of 10 wt.% to 40 wt.% with any other disclosed components including the
amorphous or crystalline silica
material.
[0106]. The limestone and the combustible material in combination at melt
temperatures contribute to
a produce amorphous silica particles and other products with an increased
density. Such embodiments of the
batch after melting and cooling may produce amorphous silica particles have a
density greater than 2.65 g/ml
and 3.6 g/ml and in some embodiments, a density greater than 2.80 g/ml and
less than 4.0 g/ml. In
embodiments wherein the batch consists essentially of cullet, sand or a
combination of cullet and sand in a
concentration of 5 wt. % to 20 wt. %, limestone in a concentration range of 25
wt.% to 40 wt.%; iron oxide, iron
ore, or a combination thereof in a concentration range of 30 wt.% to 40 wt.%,
combustible material in a
concentration of 2 wt. % to 12 wt.% and fluxes in a range of 0 wt. % to 15
wt.%, the amorphous silica particles
produces after melting and cooling may have a density greater than 3.0 g/ml
and less than 4.0 g/ml. In some
embodiments, the limestone may be in concentration range of 25 wt.% to 40
wt.%. The fluxes may comprise or,
in some embodiments, consist essentially of, at least one of sodium carbonate
and potassium carbonate.
[0107]. Further, embodiments of the method comprise adding a combination of
limestone and iron
oxide, iron ore or combination thereof to a glass cullet. The limestone and
iron oxides may be combined with
the amorphous and/or crystalline silica in any concentration that produces a
higher density amorphous silica
product after melting and cooling together. For example, an embodiment of the
method of producing an
abrasive particle comprises preparing a batch comprising glass cullet in a
concentration range of 20 wt.% to 55
wt.%, at least one of iron oxide and iron ore in a concentration range of 20
wt.% to 55 wt.%, and limestone in a
concentration range of 8.0 wt.% to 40 wt.%. The batch may be further processed
as described for other
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embodiment to produce an amorphous silica particle, abrasive particles or
other amorphous silica product as
described herein. Such batches may further comprise a combustible material.
The combustible material may be
in the concentration range of 1 wt.% to 15 wt.%, for example. It may be
advantages to add a recycled glass
cullet that includes other recycled combustible products. In such a case, the
recycled glass may not have to be
cleaned to a degree required by other uses of recycled glass cullet processes
such as, but not limited to,
container or float glass production.
[0108]. In such embodiments, limiting the limestone concentration to a
higher range may produce an
amorphous silica particle with improved properties for certain applications.
Therefore, an embodiment of the
method of producing an abrasive particle comprises preparing a batch
comprising glass cullet in a concentration
range of 20 wt.% to 55 wt.%, at least one of iron oxide and iron ore in a
concentration range of 20 wt.% to 55
wt.%, and limestone in a concentration range of 25 wt.% to 40 wt.%. In other
embodiments, the limestone may
in a concentration range from 25 wt.% to 35 wt.%. Further, to adjust melt
temperatures or viscosity of the melt
effluent (as in other embodiments) the batch may comprise fluxes in the range
of 0.5 wt.% to 20 wt.%. In such
embodiments, the fluxes may consist essentially of at least one of sodium
carbonate and potassium carbonate.
[0109]. In a still further embodiment, the method of producing an abrasive
particle, comprising
preparing a batch consisting essentially of glass cullet in a concentration
range of 20 wt.% to 55 wt.%, at least
one of iron oxide or iron ore in a concentration range of 20 wt.% to 55 wt.%;
and limestone in a concentration
range of 8.0 wt.% to 40 wt.%, melting the batch in a furnace to produce a melt
effluent. In a still further
embodiment of the method combining the glass cullet, limestone and iron, the
method consists essentially of
preparing a batch comprising glass cullet in a concentration range of 20 wt.%
to 55 wt.%, at least one of iron
oxide and iron ore in a concentration range of 20 wt.% to 55 wt.%, limestone
in a concentration range of 20
wt.% to 40 wt.%, and fluxes in a concentration range of 1 wt. % to 15 wt.%,
for example.
[0110]. In these embodiments, the glass cullet may be substitute either
completely or partially with
silica sand or other silica containing material on a molar equivalent amount
of silicon. If the glass cullet is either
partially or completely replaced with silica sand or other silica containing
material, the amount of flux may be
increased to compensate for the flux that was not added with the glass cullet.
In some embodiments, the upper
range of the flux concentration range may be increased to compensate for this
"missing" flux.
[0111]. Embodiments of the invention may comprise adding iron ore or other
material comprising iron
compounds into the batch prior to melting. Thus, further embodiments for a
method of producing an abrasive
product include preparing a batch from silica sand, at least one of iron
oxide, iron ore, and other iron containing
minerals or materials and limestone. The melt temperature and the viscosity of
the furnace effluent (melt
effluent) may be adjusted with the addition of fluxes as described herein.
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[0112]. In one embodiment, the method of producing an abrasive particle
comprises preparing a batch
comprising silica sand, a combination of iron oxides, iron ore or a
combination thereof in a range of 20 wt.% to
55 wt.%, and limestone in a concentration range of 25 wt.% to 45 wt.%. In some
embodiments, the combination
of iron oxide, iron ore or a combination thereof and limestone or other source
of calcium is in a range of from 40
wt.% to 80 wt.%.
[0113]. As such, methods of preparing a batch comprising silica sand in a
concentration range of 5 wt.%
to 25 wt.%, at least one of iron oxide or iron ore in a concentration range of
20 wt.% to 55 wt.%, and limestone
in a concentration range of 25 wt.% to 45 wt.%. The method further comprises
melting the batch in a furnace to
melt effluent and cooling the melt effluent to form amorphous silica particles
or mass and crushing the
amorphous silica particles or mass to form abrasive particles. In some more
specific embodiment, the silica sand
of this batch may be in a concentration range of 8 wt.% to 18 wt.%.
[0114]. In some embodiments, the batch comprising silica sand, a
combination of iron oxides, iron ore
or a combination thereof in a range of 20 wt.% to 55 wt.%, and limestone in a
concentration range of 25 wt.% to
45 wt.%. may additionally comprise glass cullet. For example, a batch in this
embodiment may comprise glass
cullet in a concentration range of 0.5 wt.% to 10 wt.% or in a more specific
embodiment, the batch comprises
glass cullet in a concentration range of 2.0 wt.% to 8.0 wt.%.
[0115]. Similar to all other embodiments, the batch may comprise iron oxide
in a concentration range of
20 wt.% to 40 wt.% and the iron oxide may consist essentially of magnetite.
[0116]. Also, the batch comprising silica sand, a combination of iron
oxides, iron ore or a combination
thereof in a range of 20 wt.% to 55 wt.%, and limestone in a concentration
range of 25 wt.% to 45 wt.%. may
additionally comprise glass cullet (as described above), fluxes, and/or a
combustible material. These
embodiments of the method may comprise combustible materials in a
concentration range of 1 wt.% to 15
wt.%.
[0117]. Mineral slags comprise silica compounds and other metal oxides and,
therefore, they may be
used in embodiments of the methods. Such slags may comprise components above
acceptable limits by
industrial hygiene organizations. In embodiments of the invention, glass
cullet, sand, and/or additional oxides
such as, iron oxide, aluminum oxide, titanium oxide and zirconium oxide, for
example, may be added to the
batch to produce an amorphous silica product having the potentially toxic
components below the acceptable
limits. Mineral slag including, but not limited to, iron slag, nickel slag,
copper slag, platinum slag, and coal slag,
may also be blended into a batch to produce an amorphous silica product. The
mineral slags may be combined
with any of the components as described herein including, but not limited to,
silica sand, glass cullet, iron ore or
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iron oxides, limestone, combustible materials, fluxes, and/or the substitutes
for these materials as described
herein.
[0118]. Thus, further embodiments of the method of producing an abrasive
particle may comprise
preparing a batch comprising at least one mineral slag in a concentration
range of 40 wt.% to 70 wt.%, glass
cullet in a concentration range of 5 wt.% to 25 wt.%, at least one of iron
oxide or iron ore in a concentration
range of 10 wt.% to 35 wt.%, and limestone in a concentration range of 0 wt.%
to 15 wt.%. The batch may be
melted and further processed as described herein. The glass cullet may be
added in different concentrations to
vary the manufacturing costs, density and hardness. As such, the glass cullet
may be in a concentration range of
8 wt.% to 18 wt.%. or the glass cullet may be in a concentration range of 10
wt.% to 20 wt.%. As in other
embodiments, the batch may comprise fluxes in the range of 0.5 wt.% to 20
wt.%. These embodiments may
produce amorphous glass products having a specific gravity of greater than 2.8
g/ml or a specific gravity of
greater than 3.0 g/ml and less than 4.0 g/ml. The batches comprising mineral
slags may also comprise the any of
the components described herein.
Preparing the Glass Batch, Batch, or Melt Composition
[0119]. .. Embodiments of the method comprise preparing a glass batch. There
are three general
composition classifications of the glass batches; glass batches based upon
crystalline silica primarily
such as sands and crystalline silica minerals, glass batches based upon
amorphous silica or cullet
primarily such as glass cullet or recycled glass, and glass batches based upon
a combination of
crystalline silica and amorphous silica. The crystalline silica may be
obtained from minerals and sands,
such as quartz, cristobalite and tridymite.
Crystalline Silica Glass Batches
[0120]. The crystalline silica may be mixed with additional components,
such as, but not limited
to, melting point reducing agents (fluxes), glass formers, stabilizers,
density increasing or decreasing
components, hardness increasing or decreasing components, toughness increasing
components, or
combinations thereof, for example.
[0121]. .. The melting point of crystalline silica is high, about 1710 C (3110
F). Without special
equipment such as induction furnaces and specialty materials, it is difficult
to directly convert
crystalline silica to amorphous silica. However, the melting point may be
reduced by addition of at
least one melting point reducing agent (flux). In some embodiments, preparing
a glass batch
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comprises mixing the crystalline silica containing material with at least one
melting point reducing
agent. Reducing the melting point of the glass batch may result in a more
efficient process that
requires less energy to convert the crystalline silica to amorphous silica.
Melting point reducing agents
are compounds or elements that lower the temperature or temperature range that
the crystalline silica
is converted to amorphous silica or melts first and solubilizes the
crystalline silica.
[0122]. In one embodiment, the glass batch may comprise, or consist
essentially, of crystalline
silica and at least one a metal, a metal oxide or a metal silicate. For
example, in one embodiment, the
glass batch may comprise, or consist essentially of, crystalline silica in the
range of 50 wt. % to 75 wt. %
and at least one of iron oxides or iron silicates in the range of 20 wt.% to
45 wt.%. The iron oxide acts
as both a flux for the glass batch and to increase the density of the
amorphous silica product above the
density of a pure amorphous silica or, in some embodiments, above the density
of container glass. To
further reduce the melting point of the glass batch, the glass batch may
comprise additional fluxes.
The additional fluxes may be in a range of 0 wt.% to 25 wt.%, for example, or
in the range of 0 wt.% to
12 wt.% in other embodiments.
[0123]. In an embodiment, the glass batch consists essentially of
crystalline silica in the range of
50 wt. % to 75 wt. %, at least one of iron oxides or iron silicates in the
range of 20 wt.% to 45 wt.%, and
additional fluxes may be in a range of 2 wt.% to 25 wt.%.
[0124]. A further embodiment of the method comprises preparing a glass
batch consisting
essentially of crystalline silica, a combination of iron oxides and calcium
compounds in a concentration
from 50 wt.% to 80 wt. % and fluxes in a concentration range of 2 wt.% to 20
wt.%. In such an
embodiment, individually the iron oxides and the calcium compounds may be in a
concentration range
of 25 wt. % to 40 wt. %. In such embodiments, the iron oxide may be magnetite
and the calcium
compounds may be limestone. A still further embodiment of the method comprises
preparing a glass
batch consisting essentially of crystalline silica, a combination of iron
oxides and calcium compounds in
a concentration from 50 wt.% to 80 wt. %; fluxes in a concentration range of 2
wt.% to 20 wt.%, and a
combustible material. The combustible material may be in a concentration range
of .5 wt.% to 15
wt.%.
[0125]. Other embodiments of the method consist essentially of preparing a
glass batch
consisting of mineral slags, sand, iron oxide, calcium compounds, and fluxes.
As in other
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embodiments, the fluxes may be in a concentration sufficient to lower the melt
temperature and lower
the viscosity of the melt effluent as desired, such as in a concentration
range of 0 wt.% to 15 wt.%, for
example. The mineral slags may be in a concentration range of from 30 wt.% to
60 wt. %, for example.
The concentration of mineral slag may be determined by the dilution factor
needed to lower the
concentration of any toxic components below hazardous levels as determined by
indu In some such
embodiments, a combination of iron oxides and calcium compounds in a
concentration from 50 wt.%
to 80 wt. % in total. In such an embodiment, individually the iron oxides and
the calcium compounds
may be in a concentration range of 25 wt. % to 40 wt. %. In such embodiments,
the iron oxide may be
magnetite and the calcium compounds may be limestone.
[0126]. For some applications, the glass batch may comprise higher
concentrations of iron
oxides. In another embodiment, the glass batch may comprise crystalline silica
in the range of 50 wt. %
to 70 wt. % and at least one of iron oxides and iron silicates in the range of
30 wt.% to 50 wt.%. Again,
to further reduce the melting point of the glass batch, the glass batch may
further comprise additional
fluxes. The additional fluxes may be in a range of 0 wt.% to 25 wt.%, for
example, or in the range of 0
wt.% to 10 wt.% in other embodiments. In an embodiment, the glass batch
consists essentially of
crystalline silica in the range of 50 wt. % to 70 wt. %, at least one of iron
oxides or iron silicates in the
range of 30 wt.% to 50 wt.%, and additional fluxes may be in a range of 2 wt.%
to 25 wt.%.
[0127]. The composition of the amorphous silica product will be directly
related to
concentrations of the glass batch except the crystalline silica will be in a
predominantly amorphous
state. The other components may also be amorphous and reported as oxides.
[0128]. In another embodiment, the glass batch may comprise crystalline
silica in the range of
50 wt. % to 70 wt. %, metal oxides or metal silicates in the range of 30 wt.%
to 50 wt.%, and additional
fluxes in the range of 0 wt.% to 25wt.%. In another embodiment, the glass
batch may comprise
crystalline silica in the range of 40 wt. % to 60 wt. %, metals or metal
oxides or metal silicates in the
range of 30 wt.% to 60 wt.%, and additional fluxes in the range of 2 wt.% to
25wt.%. In some cases,
the metal oxides may be a combination of iron oxides with other metals or
metal oxides to alter the
properties of the amorphous silica product. For example, the metal oxides may
be aluminum oxides,
zirconium oxides, a combination of aluminum oxides and iron oxides, a
combination of zirconium
oxides and iron oxides, or a combination of aluminum oxides, zirconium oxides,
and iron oxides.
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Similarly, in some cases, the metal silicates may be a combination of iron
silicates with other metals or
metal silicates to alter the properties of the amorphous silica products. In
some embodiments, the
aluminum oxides or aluminum silicates may be present in a range from 0.5 wt.%
to 10 wt.%. In some
embodiments, the zirconium oxides or silicates may be present in a range of
from 0.5 wt.% to 10 wt.%.
In some additional embodiments, a combination of aluminum oxides and/or
silicates and zirconium
oxides and/or silicates may be present in a range of from 0.5 wt.% to 10.
[0129]. .. In one embodiment, the glass batch may comprise silicon oxide
(amorphous or
crystalline) in the range of 50 wt. % to 70 wt. %, iron oxides or iron
silicates in the range of 27 wt.% to
47 wt.%; and fluxing compounds in the range of 2 to 15 wt. %. In a similar
embodiment, the glass
batch may consist essentially of silicon oxide in the range of 50 wt. % to 70
wt. %, iron oxides or iron
silicates in the range of 27 wt.% to 47 wt.%; and fluxing compounds in the
range of 2 to 15 wt. %.
[0130]. Such embodiments will result in an amorphous silica product
comprising silicon oxide in
the range of 50 wt. % to 70 wt. % and iron oxides in the range of 27 wt.% to
47 wt.%. Other
embodiments of the amorphous silica product or abrasive blasting media will
consist essentially of
silicon oxide in the range of 50 wt. % to 70 wt. %, iron oxides in the range
of 27 wt.% to 47 wt.%, and
fluxing compounds in the range of 2 to 15 wt. %.
Amorphous Silica Glass Batch
[0131]. In one embodiment, the glass batch may comprise or consist
essentially of amorphous
silica and at least one metal or at least one metal oxide. For example, in one
embodiment, the glass
batch may comprise amorphous silica in the range of 40 wt. % to 75 wt. % and
metal, metal silicates,
and/or metal oxides in the range of 20 wt.% to 45 wt.%. In some embodiments,
the metal, metal
silicates, or metal oxides may be iron oxides, iron silicates, zirconium
oxides, zirconium silicates,
aluminum oxides, aluminum silicates, or combinations thereof. The other metals
and metal oxides
described herein may be components of other embodiments of the glass batches.
[0132]. As in the crystalline silica glass batch, the iron oxide or iron
silicates acts as both a flux
for the glass batch and to increase the density of the amorphous silica
product above the density of a
pure amorphous silica. To further reduce the melting point of the glass batch,
the glass batch may
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further comprise additional fluxes. The additional fluxes may be in a range of
0 wt.% to 25 wt.%, for
example, or in the range of 0 wt.% to 10 wt.% in other embodiments.
[0133]. Amorphous silica may be added to the glass batch from various
sources. The sources of
the amorphous silica may be glass cullet, recycled glass, unprocessed glass
waste, partially processed
glass waste, diatomaceous earth, or combinations thereof. Glass cullet,
recycled glass and other glass
waste comprise amorphous silica and other components including fluxes,
stabilizers, formers, and
colorants, for example. Therefore, the glass batch composition may account for
the additional
components in the source of the amorphous silica. For example, cullet may
comprise fluxes in the
range of 10 wt.% to 20 wt.%. If the glass batch comprises 60% glass cullet,
the amount of flux added
into the glass batch with the cullet will be between 6 wt.% and 12wt%.
[0134]. For some applications, the glass batch may comprise higher
concentrations of metals,
metal silicates, or metal oxides. In another embodiment, the glass batch may
comprise amorphous
silica in the range of 40 wt. % to 70 wt. % and iron oxides in the range of 30
wt.% to 50 wt.%. Again, to
further reduce the melting point of the glass batch, the glass batch may
further comprise additional
fluxes. The additional fluxes may be in a range of 0 wt.% to 18 wt.%, for
example, or in the range of 0
wt.% to 10 wt.% in other embodiments. In an embodiment, the glass batch
consists essentially of
crystalline silica in the range of 50 wt. % to 70 wt. %, iron oxides in the
range of 30 wt.% to 50 wt.%,
and additional fluxes may be in a range of 2 wt.% to 20 wt.%.
[0135]. .. In another embodiment, the glass batch may comprise a silica in the
range of 50 wt. %
to 70 wt. %, metals, metal silicates, and/or metal oxides in the range of 30
wt.% to 50 wt.%, and
additional fluxes in the range of 0 wt.% to 25wt.%. In one embodiment, the
metals, metal silicates, or
metal oxides are iron, iron silicates, or iron oxides. In some additional
cases, the metal oxides may be a
combination of iron oxides with other metals or metal oxides to alter the
properties of the amorphous
silica product. For example, the metal oxides may be aluminum oxides,
zirconium oxides, a
combination of aluminum oxides and iron oxides, a combination of zirconium
oxides and iron oxides,
or a combination of aluminum oxides, zirconium oxides, and iron oxides. In
some embodiments, the
aluminum oxides may be present in a range from 0.5 wt.% to 12 wt.%. In some
embodiments, the
zirconium oxides may be present in a range of from 0.5 wt.% to 12 wt.%. In
some additional
embodiments, a combination of aluminum oxides and zirconium oxides may be
present in a range of
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from 0.5 wt.% to 10. At least a portion of the metal oxides may be substituted
with metal silicates, for
example.
[0136]. As such an embodiment of the amorphous silica product produced from
amorphous
sources of silica comprise amorphous silicon oxide in the range of 50 wt. % to
75 wt. %, a combination
of iron oxides and aluminum oxides, wherein the iron oxides and the aluminum
oxides together are in
in the range of 15 wt.% to 50 wt.%, wherein the aluminum oxides are in a range
of 0.5 wt.% to 10
wt.%., and fluxing compounds in the range of 0 to 10 wt. %. In a more specific
embodiment, the
aluminum oxides may be in the range of 3 to 10 wt.%.
[0137]. Similarly, an embodiment of the amorphous silica product comprises
amorphous silicon
oxide in the range of 50 wt. % to 75 wt. %, a combination of iron oxides and
zirconium oxides, wherein
the iron oxides and the zirconium oxides together are in in the range of 12
wt.% to 50 wt.%, wherein
the zirconium oxides are in a range of 0.5 wt.% to 10 wt.%., and fluxing
compounds in the range of 0 to
wt. %. In a more specific embodiment, the aluminum oxides may be in the range
of 0.5 wt.% to 5
wt.%.
[0138]. In either of the above embodiments, the zirconium oxides or the
aluminum oxides may
be substituted with a combination of aluminum oxides and zirconium oxides.
[0139]. Combinations of Amorphous Silica and Crystalline Silica
[0140]. In some embodiments, the silica in the glass batch may be a
combination of crystalline
silica and amorphous silica. In any of the above embodiments, the crystalline
silica or the amorphous
silica in the glass batch may be replaced with a combination of amorphous
silica and crystalline silica in
the stated compositional ranges. For example, the glass batch may comprise
sand and glass cullet. In
other cases, the crystalline silica may be from a crystalline silica mineral,
such as the addition of
bauxite to the glass batch comprising cullet, the mineral, bauxite for
example, may comprise a
combination of the crystalline silica, iron oxides, and additional fluxes such
as aluminum oxide.
[0141]. .. By processing the glass batches in either glass manufacturing
methods or frit
manufacturing methods, amorphous glass products will be produced. The
amorphous glass may be
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used for any purpose including, but not limited to, abrasive blasting media,
proppants, high density
amorphous glass product, and other products. Further embodiments of preparing
a glass batch may
include mixing the crystalline silica sand with recycled glass and/or cullet,
if desired.
Heating the Glass Batch to produce amorphous silica products
[0142]. Embodiments of the method comprise converting crystalline silica
into an amorphous
silica produce amorphous silica sand, gravel, or other particles, sheets, or
fibers. The method may
comprise heating the glass batch comprising crystalline silica to a
temperature above the temperature
that results in the phase change from the crystalline silica to an amorphous
form of silica. The furnace
may increase the temperature of the glass batch above the melting temperature
of crystalline silica.
The melting point of pure silica dioxide is 3110 F (1710 C) but may be lowered
by addition of fluxes as
described above.
[0143]. Embodiments of the heating the glass batch comprise feeding the
glass batch into a
glass melting furnace. The furnace may be a continuous or batch furnace. There
are various types of
glass melting furnaces including pot furnaces (for batch processing), day tank
furnaces, gas fired
furnaces, and electric furnaces.
[0144]. In an embodiment comprising a continuous furnace, the glass batch
may be heated to
and become molten at approximately 1100 C to 1700 C, more specifically a
temperature range 1300 C
to 1600 C, depending upon the composition of the glass batch. In some
embodiments of the method,
the glass batch may be heated to or above the melt temperature of the glass
batch. In another
embodiment, the glass batch may be heated to a temperature between the melt
temperature and the
temperature in which the crystalline silica converts to amorphous silica. As
previously described, the
melt temperature and the temperature at which the crystalline silica converts
to amorphous silica will
depend on the composition of the glass batch. In such embodiments, the glass
batch may be heated to
a temperature below the gob temperature. In certain batch embodiments, the
glass batch may be
heated to similar temperatures. In certain embodiments, the process does not
comprise refining the
molten glass batch to remove all gas bubbles. This process is necessary to
produce clear glass
containers or plate glass but may not be necessary to produce amorphous silica
sand, gravel, and other
particles, sheets, or fibers.
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[0145]. Alternatively, a further embodiment of the process comprises
heating granules, grains,
or particles of sand or rock comprising crystalline silica individually in
combination with the other steps
described herein. In further embodiments, the furnace may be a rotating kiln
furnace.
[0146]. The effluent of the furnace may be a ribbon of molten amorphous
silica.
Cooling the furnace effluent
[0147]. Embodiments of the method of the invention comprise cooling the
ribbon effluent from
the furnace. Therefore, a method may comprise cooling or allowing the
amorphous mass cool to a
hardened state. In some embodiments, the process may comprise rapidly cooling
or quenching the
ribbon of furnace effluent such as by fritting. Fritting of the molten glass
causes a thermal gradient and
violent fracturing of the solidifying amorphous material. The quenching of the
molten glass may be
performed by contact with a fluid such as water. The molten glass ribbon may
overflow the furnace
into a bath of fluid or the fluid may be spraying of the molten glass.
[0148]. The solidified solid is an amorphous silica product. The fracturing
of the glass results in
small particles that may be classified into particle size ranges. The various
particle size ranges may find
application in the products described herein.
[0149]. Embodiments of the method may further comprise crushing or
otherwise comminuting
at least a portion of the amorphous silica to particles to a smaller size or
to narrow the particle size
distribution. The desired particle size distribution may be the appropriate
particle size distribution for
abrasive blasting, use in mortar, plaster, concrete, and asphalt paving,
foundry sand, and/or the
production of bricks, for example.
[0150]. Optionally, an embodiment of the process may comprise annealing
fractured
amorphous silica particle or the crushed or otherwise comminuted amorphous
mass.
[0151]. The molten glass batch exits the refractory through a weir. The
weir is designed to
provide an evenly shaped flow of molten glass for quenching. The furnace may
have more than one
weir to ensure proper molten glass ribbon shape and size for efficient
quenching and fracturing of the
solidifying amorphous silica.
[0152]. In certain embodiments, quenching the molten amorphous mass should
be performed
properly to ensure fracturing of the amorphous solid upon rapid cooling.
Ideally, the quenched
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amorphous solid comprises a particulate product having a desired particle size
range, average particle
size, and/or particle size distribution. The furnace effluent flow rate and
shape may be controlled to
provide uniform quenching of the amorphous silica.
Applications and products
[0153]. An embodiment of a process consists essentially of transforming
crystalline or
polycrystalline sand, grains, particles, or rock into amorphous sand, gravel
or other particles for the
purpose of rendering the material substantially free of crystalline silica (a
known carcinogen) making it
a safe replacement for naturally occurring products containing various forms
of crystalline silica in
consumer and industrial applications through a process comprising heating the
crystalline or
polycrystalline sand, grains, particles or rock into an amorphous mass and
reducing the size of the
amorphous mass for use in the desired application.
[0154]. Still further embodiments of the process may comprise using
amorphous sand for
applications that currently of previously used crystalline or polycrystalline
sand products including, but
not limited to silica sand product applications and crushed rock products.
[0155]. The amorphous sand and articles produced by this process are
especially useful for
processes that produce airborne dust products such as for abrasive blasting or
products that will be cut
such as cement blocks, pavers, or bricks to avoid producing a potentially
dangerous dust if
crystalline silica sand was used, or are useful in recycling, repurposing, or
otherwise transforming
materials that might other wise be destined to landfills into products of
value..
[0156]. Products and applications for the amorphous silica particles
include but are not limited
to, crystalline silica free amorphous silica sand, crystalline silica free
amorphous silica gravel, crystalline
silica free amorphous cullet or feedstock, amorphous silica blasting material,
crystalline silica free
concrete, grout, manufactured stone, pavers, or mortar, concrete blocks made
from crystalline silica
free concrete, crystalline silica free bricks comprising crystalline free
amorphous silica, crystalline silica
free glass sheets, and crystalline silica free glass fibers. For example, the
bricks may comprise
crystalline silica free sand in a concentration from 50% to 60% by weight,
alumina in a concentration
from 20% to 30% by weight, and lime in a concentration from 2 to 5% by weight.
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[0157]. .. As such, an embodiment of the amorphous silica product comprises
amorphous silicon
oxide in the range of 50 wt. % to 75 wt. %, a combination of iron oxides and
aluminum oxides, wherein
the iron oxides and the aluminum oxides together are in in the range of 15
wt.% to 50 wt.%, wherein
the aluminum oxides are in a range of 0.5 wt.% to 10 wt.%., and fluxing
compounds in the range of 0 to
wt. %. In a more specific embodiment, the aluminum oxides may be in the range
of 3 to 10 wt.%.
[0158]. .. Similarly, an embodiment of the amorphous silica product comprises
amorphous silicon
oxide in the range of 50 wt. % to 75 wt. %, a combination of iron oxides and
zirconium oxides, wherein
the iron oxides and the zirconium oxides together are in in the range of 12
wt.% to 50 wt.%, wherein
the zirconium oxides are in a range of 0.5 wt.% to 10 wt.%., and fluxing
compounds in the range of 0 to
10 wt. %. In a more specific embodiment, the aluminum oxides may be in the
range of 0.5 wt.% to 5
wt.%. In either of the above embodiments, the zirconium oxides or the aluminum
oxides may be
substituted with a combination of aluminum oxides and zirconium oxides.
[0159]. .. Other embodiments of the amorphous silica product comprises
unusually low levels of
silicon in the form of amorphous silicon oxide in the range of 13 wt.% to 25
wt%, iron oxides in the
range of 0% wt.% to 40 wt.%, Aluminum oxides in the range of 0 wt.% to 12
wt.%, magnesium oxides in
the range of 0 wt.% to 3 wt.%, calcium oxides in the range of 8 wt.% to 25
wt%., alkali metals in the
range of 0 wt.% to 1 wt. %, and carbon in the range of 0 wt.% to 10 wt. %.
Such products exhibit
excellent levels of density, often above 3.0 g/cm3, and favorable hardness for
their applications, often
in excess of 640 Knoop Hardness.
[0160]. Limestone or other calcium glass formers may be added to the glass
batch. As such, an
embodiment of the amorphous silica product comprises amorphous silicon oxide
in the range of 10 wt.
% to 60 wt. %, a combination of iron oxides and calcium oxides, wherein the
iron oxides and the
calcium oxides together are in in the range of 15 wt.% to 85 wt.%, and fluxing
compounds in the range
of 0 to 20 wt. %. In a more specific embodiment, the iron oxides may be in the
range of 30 to 45 wt.%.
In such embodiments, the iron oxides may be in a concentration range of 10
wt.% to 60 wt. %. In
another embodiment, the iron oxides may be in a concentration range of 20 wt.%
to 50 wt. % and the
calcium oxides may be in a concentration range of 10 wt. % to 40 wt. %. In a
further embodiment, the
iron oxides may be in a concentration range of 20 wt. % to 40 wt.% and the
calcium oxides may be in a
range of 20 wt. % to 40 wt.%.
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[0161]. Further, an embodiment of the amorphous silica product consists
essentially of
amorphous silicon oxide in the range of 10 wt. % to 60 wt. %, a combination of
iron oxides and calcium
oxides, wherein the iron oxides and the calcium oxides together are in in the
range of 15 wt.% to 85
wt.%, and fluxing compounds in the range of 0 to 20 wt. %. In another such
embodiments, the iron
oxides may be in a concentration range of 10 wt.% to 60 wt. %. In another
embodiment, the iron
oxides may be in a concentration range of 20 wt.% to 50 wt. % and the calcium
oxides may be in a
concentration range of 10 wt. % to 45 wt. %. In a further embodiment, the iron
oxides may be in a
concentration range of 20 wt. % to 40 wt.% and the calcium oxides may be in a
range of 20 wt. % to 40
wt.%. The amorphous silica of the invention may be used as water insoluble or
water soluble sand and
blasting media. In a more specific embodiment, the iron oxides may be in the
range of 25 to 40 wt.%.
[0162]. Unlike recycled glass products, the amorphous silica sand produced
by the method of
the invention will comprise no non-glass residues (trash or contaminants) such
as trace fecal matter,
49 trace ferrous items or matter (unless intentionally added), 49 trace
nonferrous items or metals, 49
trace stone or ceramic items or matter, and/or 49 trace pathogens. These
substances are found in all
recycled glass cullet products.
[0163]. .. Another embodiment of the method of the present invention to
directly create a glass
cullet that is free from contaminants. Glass production facilities add crushed
recycled glass cullet into
the new glass production process to reduce the heat required to melt the
silica sand and the melt
temperature of the silica sand. The problem with this glass cullet is that it
may include contaminants
from the glass recycle process. An embodiment of the method of the present
invention is to produce
clean glass cullet directly from crystalline silica sand. This "pre-reacted"
batch material that can be
added to batch glass (much as glass cullet is used today) that will lower the
melt temperature of batch
glass.
[0164]. The amorphous silica sand, gravel, or other particles may be used
in the manufacture of
many products. For example, crystalline free silica foam glass and ceramics
may be produced. An
embodiment of the method for production of crystalline free foamed glass may
comprise blending fine
amorphous silica sand or ground amorphous silica sand with a blowing agent to
form a foam glass
precursor. The blowing agent may be any compound that produces an off-gas
during heating at
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furnace temperatures. The blowing agent may be, but is not limited to, carbon
or limestone, for
example.
[0165]. .. The method may further comprise heating the foam glass precursor in
the furnace to
cause the blowing agents to out-gas, thus expanding or foaming the molten
mass. The molten mass is
cooled and annealed to freeze the gas pockets creating a lightweight product.
Foamed glass in the
melted state can be formed into many products including insulation, blocks,
brick, or aggregate for
construction or agriculture.
[0166]. The new "virgin" amorphous silica glass cullet product would
compete directly with
recycled glass cullet. The advantage of the embodied "pre-reacted" batch
material would be it would
be 100% free of deleterious materials such as rock, ceramic, metals, or lead
that cullet producers go to
a lot of work to ensure don't get into their cullet in excessive quantities.
[0167]. As used herein, the term "no trace" means that the component is
below measurement
limits of instruments typically used to determine the concentration of the
component.
[0168]. As used herein, "amorphous silica sand" means a silica product
comprising less than 2
wt.% of crystalline silica in a primarily amorphous silica product, in a more
specific embodiment,
"amorphous silica sand" means a silica product comprising less than 1 wt.% of
crystalline silica in a
primarily amorphous silica product; and in an even more specific embodiment
for blasting products,
for example, "amorphous silica sand" means a silica product comprising less
than 0.5 wt.% of
crystalline silica in a primarily amorphous silica product.
[0169]. Stabilizers may be added to the glass batch to reduce the water
solubility of the
resultant amorphous silica products. Stabilizers include, but are not limited
to, calcium carbonate
(lime), for example. Other components that may be mixed with the crystalline
silica to produce the
glass batch include a number of metal oxides to produce desired properties in
the amorphous silica
products. For example, alumina (A1203) may be added to the glass batch to
provide increased
durability of the amorphous silica products produced from the glass batch.
Boron oxide (B203) may be
a glass former like silica and increases the chemical resistance of the glass.
[0170]. The melting point reducing agents may include, but is not limited
to, sodium carbonate,
sodium nitrate, iron oxide, iron silicates, potash, potassium carbonate,
calcium carbonate, colemanite,
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sodium oxide, calcium oxide, magnesia, alumina, aluminum oxides, alumina
silicates, lead oxide, alkali
metals, lithium, sodium, potassium, rubidium, cesium, francium, and
combinations thereof.
[0171]. Additional fluxes may include materials such as naturally occurring
products that
contain these reducing agents such as, but not limited to, feldspar, alumina
silicates comprising iron,
bauxite, clays, ball clays, Kentucky or Tennessee clay, and kaolin, for
example. Clay may be a finely-
grained natural rock or soil material that combines one or more clay minerals
with possible traces of
quartz (SiO2), metal oxides (A1203, MgO etc.) and organic matter. Ball clays
are typically kaolinitic
sedimentary clays that commonly consist of 20-80% kaolinite, 10-25% mica, 6-
65% quartz. Another
flux may be bauxite.
[0172]. For example, sodium carbonate and potassium carbonate may lower the
melting point
of crystalline silica to about 1,000 C (1830 F) in certain concentrations and
may be added to make the
melting process more efficient.
[0173]. Sodium carbonate increases the viscosity of the glass melt at a
given temperature but is
relatively expensive. Additionally, mixing sodium carbonate into the
crystalline silica glass batch
(and/or another melting point reducing agent), without the addition of a
stabilizing agent such as, but
not limited to lime, may cause the amorphous silica products to be at least
slightly water soluble.
Water soluble amorphous silica products may be more environmentally friendly
that insoluble
amorphous silica. Thus, a method of producing a water-soluble amorphous silica
sand, gravel, or other
particles comprises mixing a temperature reducing agent with crystalline
silica without the addition of
a stabilizer such as calcium carbonate and melting the batch glass to produce
an amorphous silica
product to be water soluble.
Density and Hardness affecting components
[0174]. Embodiment of the amorphous silica products may comprise metals or
metal oxides.
These metals and metal oxides include refractory metals, iron, titanium,
vanadium, chromium,
manganese, zirconium, zircon, niobium, molybdenum, ruthenium, rhodium,
hafnium, tantalum,
tungsten, rhenium, osmium, iridium, and oxides or silicates of these metals,
for example.
[0175]. Additional metals include aluminum, aluminum oxides, aluminum
silicates. The alumina
may be from clay and, in some embodiments, low alkali clay. Some clays are up
to 10% alumina
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[0176]. Embodiments of the amorphous silica products may comprise
components that change
the hardness of the resultant amorphous silica products. Alkalis and lead
oxides will decrease hardness
in the resultant amorphous product, whereas addition of CaO, MgO, ZnO, A1203,
B203, zirconium,
zircon, zirconium oxides, iron and iron oxides will result in amorphous silica
products with greater
hardness.
EXAMPLES
[0177]. CuIlet was obtained from a glass recycling facility. The
composition of the cullet was
approximately as follows:
[0178]. Typical CuIlet Composition
SiO2 74. wt.%
MgO 0.3 wt.%
CaO 11.3 wt.%
Na0 13 wt.%
K20 0.2 wt.%
A1203 0.7 wt.%
Fe2O3 0.01 wt.%
[0179]. In embodiments of the glass formulations, the silicon oxides may
be added in the form
of cullet, sand, other sources of silicon oxides, or combinations thereof.
[0180]. The melts were performed in a [Make and Model of Furnace] CF1700
muffle furnace
manufactured by Across International.
EXAMPLE 1
[0181]. A melt batch (Sample 2789) was prepared comprising the following
composition, silica
dioxide (5i02) at 85 wt.%, sodium oxide (Na0) at 14 wt.%, and iron oxide
(Fe2O3) at 1 wt.% in the melt
batch.
[0182]. The melt batch was melted in a crucible in a batch furnace at
approximately 1525 C.
The melted batch was then quenched in water. The solidified glass was sent for
analysis for specific
gravity and hardness. The specific gravity was determined to be 2.25. The
Knoop hardness was
determined to be 481.8.
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EXAMPLE 2
[0183]. A melt batch (Sample 2790) was prepared comprising the following
composition, silica
dioxide (5i02) at 84 wt.%, zirconium oxide (ZrO) at 13 wt. %, sodium oxide
(Na0) at 1 wt.%, and iron
oxide (Fe2O3) at 2 wt.% in the melt batch.
[0184]. The melt batch was melted in a crucible in a batch furnace at
approximately 1550 C.
The melted batch was then quenched in water. The solidified glass was sent for
analysis for specific
gravity and hardness. The specific gravity was determined to be 2.36. The
Knoop hardness was
determined to be 493.7.
EXAMPLE 3
[0185]. A melt batch (Sample 2791) was prepared comprising the following
composition, silica
dioxide (5i02) at 83 wt.%, zirconium oxide (ZrO) at 2 wt. %, sodium oxide
(Na0) at 10 wt.%, and iron
oxide (Fe2O3) at 5 wt.% in the melt batch.
[0186]. The melt batch was melted in a crucible in a batch furnace at
approximately 1575 C.
The melted batch was then quenched in water. The solidified glass was sent for
analysis for specific
gravity and hardness. The specific gravity was determined to be 2.35. The
Knoop hardness was
determined to be 540.6.
EXAMPLE 4
[0187]. A melt batch (Sample 2792) was prepared comprising the following
composition, silica
dioxide (5i02) at 80 wt.%, zirconium oxide (ZrO) at 5 wt. %, sodium oxide
(Na0) at 5 wt.%, and iron
oxide (Fe2O3) at 10 wt.% in the melt batch.
[0188]. The melt batch was melted in a crucible in a batch furnace at
approximately 1625 C.
The melted batch was then quenched in water. The solidified glass was sent for
analysis for specific
gravity and hardness. The specific gravity was determined to be 2.86. The
Knoop hardness was
determined to be 638.4.
EXAMPLE 5
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[0189]. A melt batch (Sample 2799) was prepared comprising the following
composition, silica
dioxide (5i02) at 70 wt.%, zirconium oxide (ZrO) at 2 wt. %, sodium oxide
(Na0) at 5 wt.%, aluminum
oxide (A1203) at 3 wt.%, and iron oxide (Fe2O3) at 20 wt.% in the melt batch.
[0190]. The melt batch was melted in a crucible in a batch furnace at
approximately 1600 to
1625 C. The melted batch was then quenched in water. The solidified glass was
sent for analysis for
specific gravity and hardness. The specific gravity was determined to be 2.5.
The Knoop hardness was
determined to be 615.4.
EXAMPLE 6
[0191]. A melt batch (Sample 2800) was prepared comprising the following
composition, silica
dioxide (5i02) at 65 wt.%, zirconium oxide (ZrO) at 2 wt. %, sodium oxide
(Na0) at 4 wt.%, aluminum
oxide (A1203) at 6 wt.%, and iron oxide (Fe2O3) at 23 wt.% in the melt batch.
[0192]. The melt batch was melted in a crucible in a batch furnace at
approximately 1600 to
1625 C. The melted batch was then quenched in water. The solidified glass was
sent for analysis for
specific gravity and hardness. The specific gravity was determined to be 2.69.
The Knoop hardness
was determined to be 668.7.
EXAMPLE 7: Melt batch from sand
[0193]. A melt batch (Sample 2801) was prepared comprising the following
composition, silica
dioxide (5i02) at 60 wt.%, zirconium oxide (ZrO) at 2 wt. %, sodium oxide
(Na0) at 3 wt.%, aluminum
oxide (A1203) at 8 wt.%, and iron oxide (Fe2O3) at 27 wt.% in the melt batch.
[0194]. The melt batch was melted in a crucible in a batch furnace at
approximately 1600 to
1625 C. The melted batch was then quenched in water. The solidified glass was
sent for analysis for
specific gravity and hardness. The specific gravity was determined to be 2.52.
The Knoop hardness
was determined to be 721.9.
EXAMPLE 8: Melt batch from cullet
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[0195]. A melt batch (Sample 2802) was prepared comprising the following
composition, cullet
(approximate composition above) at 90 wt.%, zirconium oxide (ZrO) at 2 wt. %,
aluminum oxide
(A1203) at 3 wt.%, and iron oxide (Fe2O3) at 5 wt.% in the melt batch.
[0196]. The melt batch was melted in a crucible in a batch furnace at
approximately 1600 to
1625 C. The melted batch was then quenched in water. The solidified glass was
sent for analysis for
specific gravity and hardness. The specific gravity was determined to be 2.50.
The Knoop hardness
was determined to be 622.
EXAMPLE 9: Melt batch from cullet
[0197]. A melt batch (Sample 2803) was prepared comprising the following
composition, cullet
(approximate composition above) at 80 wt.%, zirconium oxide (ZrO) at 3 wt. %,
aluminum oxide
(A1203) at 4.5 wt.%, and iron oxide (Fe2O3) at 12.5 wt.% in the melt batch.
[0198]. The melt batch was melted in a crucible in a batch furnace at
approximately 1600 to
1625 C. The melted batch was then quenched in water. The solidified glass was
sent for analysis for
specific gravity and hardness. The specific gravity was determined to be 2.54.
The Knoop hardness
was determined to be 651.9.
EXAMPLE 10: Melt batch from cullet
[0199]. A melt batch (Sample 2804) was prepared comprising the following
composition, cullet
(approximate composition above) at 70 wt.%, zirconium oxide (ZrO) at 4 wt. %,
aluminum oxide
(A1203) at 6 wt.%, and iron oxide (Fe2O3) at 20 wt.% in the melt batch.
[0200]. The melt batch was melted in a crucible in a batch furnace at
approximately 1600 to
1625 C. The melted batch was then quenched in water. The solidified glass was
sent for analysis for
specific gravity and hardness. The specific gravity was determined to be 2.71.
The Knoop hardness
was determined to be 654.8.
EXAMPLE 11: Melt batch from sand
[0201]. A melt batch (Sample 2809) was prepared comprising the following
composition, silica
dioxide (5i02) at 62.45 wt.%, magnesium oxide (MgO) at 0.3 wt. %, calcium
oxide (CaO) at 0.2 wt.%,
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sodium oxide (Na0) at 7 wt.%, potassium oxide (KO) at 0.05 wt.%, and iron
oxide (Fe2O3) at 30 wt.% in
the melt batch.
[0202]. The melt batch was melted in a crucible in a batch furnace at
approximately 1625 C. A
portion of the melted batch was then quenched in water (Sample 28090) and a
portion of the melted
batch was air cooled (Sample 2809A).
[0203]. The solidified glass was sent for analysis for specific gravity and
hardness. The specific
gravity for Sample 28090 was determined to be 2.534 and its Knoop hardness was
determined to be
552.1.
[0204]. The specific gravity for Sample 2809A was determined to be 2.864
and its Knoop
hardness was determined to be 570.6.
EXAMPLE 12: Melt batch from sand
[0205]. A melt batch (Sample 2810) was prepared comprising the following
composition, silica
dioxide (5i02) at 57.45 wt.%, magnesium oxide (MgO) at 0.3 wt. %, calcium
oxide (CaO) at 0.2 wt.%,
sodium oxide (Na0) at 6.14 wt.%, potassium oxide (KO) at 0.05 wt.%, and iron
oxide (Fe2O3) at 35
wt.% in the melt batch.
[0206]. The melt batch was melted in a crucible in a batch furnace at
approximately 1625 C. A
portion of the melted batch was then quenched in water (Sample 28100) and a
portion of the melted
batch was air cooled (Sample 2810A).
[0207]. The solidified glass was sent for analysis for specific gravity and
hardness. The specific
gravity for Sample 28100 was determined to be 2.858 and its Knoop hardness was
determined to be
580.8.
[0208]. The specific gravity for Sample 2810A was determined to be 2.826
and its Knoop
hardness was determined to be 586.4.
EXAMPLE 12
[0209]. A melt batch may be prepared comprising the following composition,
silica dioxide
(5i02) at 42.3 wt.%, magnesium oxide (MgO) at 0.3 wt. %, calcium oxide (CaO)
at 0.2 wt.%, sodium
oxide (Na0) at 6.14 wt.%, wt.%, and iron oxide (Fe2O3) at 50 wt.% in the melt
batch.
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FURTHER EXAMPLES
[0210]. Additional amorphous silica products were produced from batches as
described in the
tables below. The examples exemplify the methods used to produce the amorphous
silica products
from crystalline silica, amorphous silica and combinations of amorphous and
crystalline silica.
[0211]. The examples demonstrate the use of iron oxides and/or limestone
can cheaply increase
the density of these products over the silica sand and cullet.
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[0212]. Primary Network Former: Cullet
[0213]. Crucible: Alumina or Graphite
Melt Specific Knoop Iron (III) Iron Ore
Calcium Sodium Potassium
tl Gravity Hardness Temp. C Crucible Cullet Oxide
Fe2O3 Magnetite (Taconite) Carbonate Limestone Carbonate
Carbonate Charcoal
108 2.67 1200 Alumina 65.00% 30.00% 0.00%
5.00% 0.00% 0.00%
109 2.70 1200 Alumina 68.00% 32.00% 0.00%
0.00% 0.00% 0.00%
111 2.77 539.4 1200 Alumina 65.00% 30.00%
3.00% 0.00% 0.00% 2.00%
112 2.80 554.1 1290 Alumina 65.00% 30.00%
0.00% 5.00% 0.00% 0.00%
41 2.74 589.8 1290 Alumina 65.00% 30.00%
0.00% 0.00% 5.00% 0.00%
41 2.68 1200 Alumina 65.00% 30.00% 0.00%
0.00% 5.00% 0.00%
41 2.69 1290 Alumina 65.00% 30.00% 0.00%
0.00% 5.00% 0.00%
43 2.70 1280 Alumina 66.67% 28.57% 0.00%
0.00% 4.76% 0.00%
45 2.78 1290 Alumina 46.00% 30.00% 0.00%
12.00% 12.00% 0.00%
47 2.77 1290 Alumina 26.00% 29.00% 0.00%
36.40% 8.60% 0.00%
51 2.72 1290 Alumina 30.00% 30.00% 30.00%
0.00% 0.00% 10.00%
94 2.72 1290 Alumina 68.00% 32.00% 0.00%
0.00% 0.00% 0.00%
110 2.70 1200 Alumina 65.00% 0.00% 30.00%
3.00% 2.00%
95 2.78 1380 Alumina 63.00% 0.00% 32.00%
0.00% 5.00%
96 2.67 1290 Alumina 63.00% 32.00% 0.00%
0.00% 5.00%
103 2.78 1290 Alumina 63.00% 0.00% 32.00%
0.00% 5.00%
104 2.81 530.8 1290 Alumina 63.00% 0.00%
32.00% 3.00% 2.00%
113 2.81 1390 Alumina 63.00% 0.00% 31.00%
4.00% 2.00%
114 3.01 1390 Alumina 65.00% 0.00% 30.00%
3.00% 2.00%
85 2.64 1380 Alumina 20.08% 35.66% 0.00% 36.43%
0.00% 7.83% 0.00%
91 3.24 1390 Alumina 18.78% 0.00% 33.35% 34.07%
0.00% 7.32% 6.48%
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99 2.69 1480 Alumina 23.64% 0.00% 26.36% 33.09%
7.82% 0.00% 9.09%
105 3.18 473.2 1390 Alumina 24.64% 0.00% 30.45%
33.09% 7.82% 0.00% 4.00%
42 2.73 1380 Alumina 49.00% 33.00% 6.00%
0.00% 12.00% 0.00%
22 3.07 646.2 1380 Alumina 18.78% 33.35% 34.07%
0.00% 7.32% 6.48%
23 3.02 1380 Alumina 25.00% 50.00% 13.00%
0.00% 12.00% 0.00%
31 2.95 533.1 1430 Alumina 27.92% 26.34% 37.65%
0.00% 8.09% 0.00%
32 2.97 567.3 1380 Alumina 27.97% 26.27% 37.66%
0.00% 8.09% 0.00%
33 2.93 1380 Alumina 26.00% 29.00% 36.43%
0.00% 8.57% 0.00%
34 2.89 1380 Alumina 22.37% 29.01% 34.61%
0.00% 7.43% 6.58%
35 2.87 1380 Alumina 43.00% 26.00% 19.00%
12.00% 0.00% 0.00%
36 2.87 576.8 1380 Alumina 55.00% 40.00% 0.00%
0.00% 5.00% 0.00%
37 2.85 1290 Alumina 25.40% 30.30% 34.30%
0.00% 10.00% 0.00%
38 2.83 1380 Alumina 43.00% 26.00% 19.00%
0.00% 12.00% 0.00%
39 2.79 1380 Alumina 45.00% 30.00% 13.00%
0.00% 12.00% 0.00%
40 2.76 1380 Alumina 50.00% 38.00% 0.00%
0.00% 12.00% 0.00%
1 2.54 1409 Graphite 60.00% 40.00% 0.00%
2 2.44 1450 Graphite 70.00% 30.00% 0.00%
3 2.32 1450 Graphite 80.00% 20.00% 0.00%
4 2.45 1450 Graphite 90.00% 10.00% 0.00%
20 3.13 1380 Graphite 26.05% 0.00% 24.58% 35.14%
0.00% 7.55% 6.68%
21 3.13 1380 Graphite 27.92% 0.00% 26.34% 37.65%
0.00% 8.09% 0.00%
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[0214]. Primary Network Former: Silica Sand
[0215]. Crucible: Alumina
Specific Knoop Iron (III) Sodium Potassium
Melt # Gravity Hardness Temp. C Crucible Sand Oxide Fe2O3
Magnetite Limestone Carbonate Carbonate Charcoal
86 2.67 1480 Alumina 14.57% 34.52% 0.00% 33.31% .. 4.43% ..
7.16% 6,02%
87 3.10 1480 Alumina 14.57% 34.52% 0.00% 33.31% 4.43%
7.16% 6,02%
88 3.15 1480 Alumina 14.57% 0.00% 34.52% 33.31% 4.43%
7.16% 6,02%
89 3.23 585.5 1390 Alumina 14.57% 0.00% 34.52% 33.31% 4.43%
7.16% 6,02%
100 3.23 1390 Alumina 15.50% 0.00% 36.74% 3544% 4.71%
7.61% 0,00%
106 3.08 1390 Alumina 15.50% 0.00% 36.73% 35.45% 4.72%
7.61% 0,00%
90 3.35 617.6 1390 Alumina 10.20% 4.37% 34.52% 33.31% 4.43%
7.16% 6,02%
93 3.32 1390 Alumina 10.20% 4.37% 34.52% 33.31% 4.43%
7.16% 6,02%
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[0216]. Primary Network Former: Silica Sand or Cullet, and Mineral Slag
[0217]. Crucible: Alumina
Melt Specific Knoop Magnesium Calcium
# Gravity Hardness Temp. C Crucible Sand Cullet Coal
Slag Nickel Slag Magnetite Oxide Carbonate Limestone
58 2.82 1390 Alumina 20.00% 0.00% 60.00% 15.00%
0.00% 5.00% 0.00%
62 2.63 1480 Alumina 40.00% 50.00% 0.00% 5.00% 0.00%
5.00% 0.00%
64 2.87 1480 Alumina 10.00% 0.00% 50.00% 30.00%
0.00% 10.00% 0.00%
65 2.54 1480 Alumina 20.00% 50.00% 0.00% 5.00%
10.00% 0.00% 15.00%
73 2.84 1480 Alumina 19.05% 47.62% 0.00% 23.81%
0.00% 0.00% 9.52%
75 2.77 1390 Alumina 19.05% 57.14% 0.00% 14.29%
0.00% 0.00% 9.52%
117 2.98 1390 Alumina 11.00% 50.00% 0.00% 25.00% 0.00% 0.00% 14.00%
118 2.89 1390 Alumina 9.00% 60.00% 0.00% 22.00% 0.00% 0.00% 9.00%
119 3.01 1480 Alumina 12.00% 0.00% 50.00% 20.00% 0.00% 0.00% 18.00%
120 2.88 1480 Alumina 15.00% 0.00% 60.00% 15.00% 0.00% 0.00%
10.00%
121 2.95 725,8 1480 Alumina 11.00% 50.00% 25.00% 14.00%
122 2.88 1480 Alumina 12.00% 50.00% 20.00% 18.00%
[0218]. Primary Network Former: Silica Sand or Cullet and Recycled Concrete
[0219]. Crucible: Alumina
Melt Specific Knoop Temp. Recycled
# Gravity Hardness C Crucible Sand Cullet Concrete
Magnetite Limestone Charcoal
123 2.73 1480 Alumina 0.00% 10.00% 40.00% 35.00% 15.00% 0.00%
135 2.87 1480 Alumina 0.00% 9,50% 38.00% 33.25% 14.25%
5.00%
136 3.10 679.1 1390 Alumina 10.00% 0,00% 40.00%
35.00% 15.00% 0.00%
139 3.12 625.9 1390 Alumina 0.00% 0,00% 60.00%
30.00% 5.00% 5.00%
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[0220]. Primary Network Former: Cullet and Alumina
[0224 Crucible: Graphite or Alumina
Iron (III)
Melt Specific Oxide Recycled Calcium Potassium Sodium
# Gravity Temp. C Crucible Cullet Alumina Fe2O3
Iron/Steel Oxide Sulfate Carbonate Charcoal
7 2.73 1400 Graphite 60.70% 3.10% 30.10% 0.00% 0.00% 6.10% 0.00%
8 2.76 1400 Graphite 58.70% 5.10% 30.10% 0.00% 0.00% 6.10% 0.00%
9 2.79 1400 Graphite 53.70% 5.10% 30.10% 0.00% 5.00% 6.10% 0.00%
2.69 1380 Graphite 36.80% 3.10% 45.00% 0.00% 5.00% 6.10% 4.00%
11 2.64 1380 Graphite 53.70% 5.10% 22.00% 6.00% 7.10% 6.10% 0.00%
12 2.74 1380 Graphite 53.70% 5.10% 29.10% 1.00% 5.00% 6.10% 0.00%
13 2.69 1380 Graphite 53.70% 5.10% 30.10% 0.00% 5.00% 6.10% 0.00%
14 2.63 1380 Graphite 53.70% 5.10% 30.10% 0.00% 5.00% 0.00% 6.10%
2.71 1380 Graphite 53.70% 5.10% 29.10% 0.00% 5.00% 6.10% 0.00% 1.00%
16 2.71 1380 Graphite 53.70% 5.10% 29.10% 0.00% 5.00% 6.10% 0.00% 1.00%
17 2.76 1380 Graphite 53.70% 5.10% 29.10% 0.00% 5.00% 6.10% 0.00% 1.00%
18 2.75 1380 Graphite 53.70% 5.10% 29.10% 0.00% 5.00% 6.10% 0.00% 1.00%
19 2.79 1380 Graphite 53.70% 5.10% 29.10% 0.00% 5.00% 6.10% 0.00% 1.00%
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[0222]. Primary Network Former: Cullet and Iron-Alumina Silicate (Garnet)
[0223]. Crucible: Graphite or Alumina
Specific Knoop Iron (III) Sodium Potassium
Melt # Gravity Hardness Temp. C Crucible Cullet Garnet
Oxide Fe2O3 Carbonate Sulfate Charcoal
2.66 1400 Graphite 53.50% 13.13% 24.81% 0.00% 8.56%
0.00%
6 2.74 1400 Graphite 47.18% 22.86% 21.40% 0.00%
8.56% 0.00%
84 2.67 667.4 1480 Alumina 95.00% 5.00%
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[0224]. .. The embodiments of the described amorphous silica products and
method are not
limited to the particular embodiments, components, method steps, and materials
disclosed herein as
such components, process steps, and materials may vary. Moreover, the
terminology employed herein
is used for the purpose of describing exemplary embodiments only and the
terminology is not intended
to be limiting since the scope of the various embodiments of the present
invention will be limited only
by the appended claims and equivalents thereof.
[0225]. Therefore, while embodiments of the invention are described with
reference to
exemplary embodiments, those skilled in the art will understand that
variations and modifications can
be affected within the scope of the invention as defined in the appended
claims. Accordingly, the
scope of the various embodiments of the present invention should not be
limited to the above
discussed embodiments and should only be defined by the following claims and
all equivalents.
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