U.S. patent application number 12/899511 was filed with the patent office on 2011-05-12 for binder material.
This patent application is currently assigned to The Penn State Research Foundation. Invention is credited to Nicole Robitaille Brown, Frederick Scott Cannon, James A. Devenne, JR., John T. Fox, James C. Furness, He Huang, Allura Marie Jiles, Sridhar Komarneni, Matthew Robert Lumadue, Paul Jonathan Munson, Paul D. Paulsen, Gregory Sanders, Robert C. Voigt.
Application Number | 20110108232 12/899511 |
Document ID | / |
Family ID | 43973269 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110108232 |
Kind Code |
A1 |
Cannon; Frederick Scott ; et
al. |
May 12, 2011 |
BINDER MATERIAL
Abstract
A binder material for binding a plurality of particles together
to form a conglomerate such as a carbon-containing briquette, a
sand casting core and the like is provided. The binder material can
include a collagen and/or lignin and a plurality of inorganic
particles. In some instances, the binder material can be used to
make a composite material. The composite material can include a
plurality of particles and the binder material that contains the
collagen and/or lignin. The binder material affords for the
plurality of particles to be bound together into a desired shape,
the desired shape having desirable properties.
Inventors: |
Cannon; Frederick Scott;
(State Park, PA) ; Fox; John T.; (Sellersville,
PA) ; Huang; He; (Ambler, PA) ; Voigt; Robert
C.; (State College, PA) ; Furness; James C.;
(Versailles, KY) ; Paulsen; Paul D.; (Lexington,
KY) ; Sanders; Gregory; (Canton, MI) ;
Lumadue; Matthew Robert; (Hollidaysburg, PA) ; Jiles;
Allura Marie; (State College, PA) ; Munson; Paul
Jonathan; (State College, PA) ; Komarneni;
Sridhar; (Port Matilda, PA) ; Brown; Nicole
Robitaille; (Port Matilda, PA) ; Devenne, JR.; James
A.; (Berea, OH) |
Assignee: |
The Penn State Research
Foundation
University Park
PA
|
Family ID: |
43973269 |
Appl. No.: |
12/899511 |
Filed: |
October 6, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61249037 |
Oct 6, 2009 |
|
|
|
61308115 |
Feb 25, 2010 |
|
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Current U.S.
Class: |
164/526 ;
106/38.4; 164/369 |
Current CPC
Class: |
B22C 1/188 20130101;
B22C 1/26 20130101 |
Class at
Publication: |
164/526 ;
164/369; 106/38.4 |
International
Class: |
B22C 9/10 20060101
B22C009/10 |
Claims
1. A binder material for binding a plurality of particles together
in order to make a conglomerate, said binder material comprising: a
first component containing an organic material selected from a
group consisting of a collagen and a lignin; and a second component
containing an inorganic material selected from a group consisting
of an element and an inorganic compound.
2. The binder material of claim 1, wherein said second component is
a plurality of inorganic materials.
3. The binder material of claim 1, wherein said inorganic material
is selected from a group consisting of a silicate, a ferrosilicon
and silicon.
4. The binder material of claim 3, wherein said silicate is
selected from a group consisting of an alkaline metal silicate,
alkaline earth metal silicate, an amorphous silica-rich ash and
combinations thereof.
5. The binder material of claim 4, wherein said amorphous
silica-rich ash is an amorphous silica-rich ash of rice hulls and
rice stalks.
6. The binder material of claim 3, wherein said silicon is a zero
valence silicon.
7. The binder material of claim 1, further comprising a
saccharide.
8. The binder material of claim 7, wherein said saccharide is a
monosaccharide selected from a group consisting glucose, fructose,
galactose, xylose and ribose.
9. A composite material comprising said plurality of particles and
said binder material of claim 1.
10. The composite material of claim 9, wherein said binder material
has a heat flow between -0.5 and -2.5 Watts per gram for
temperatures between 50 to 450.degree. C. as measured by a
differential scanning calorimetry protocol.
11. A conglomerate comprising said plurality of particles and said
binder material of claim 9, said plurality of particles bound
together into a desired shape by said binder material.
12. The conglomerate of claim 11, wherein said plurality of
particles are selected from a group consisting of a plurality of
coal particles, a plurality of anthracite particles, a plurality of
sand particles, a plurality of lignocellulosic particles, a
plurality of lignin particles, a plurality of carbonaceous
particles, a plurality of silicon dioxide particles, and a
plurality of aluminosilicate particles.
13. The conglomerate of claim 11, wherein 50% by mass of said
plurality of component particles have an average mean diameter of
less than 0.25 inches.
14. The conglomerate of claim 11, wherein said plurality of
particles are sand particles having an AFS grain fineness number
between 25 and 150, inclusive.
15. The conglomerate of claim 12, wherein said desired shape is a
fuel pellet.
16. The conglomerate of claim 15, wherein said fuel pellet is a
pyrolyzed fuel pellet having a plurality of silicon carbide
nanowires.
17. The conglomerate of claim 12, wherein said desired shape is a
sand casting core.
18. The conglomerate of claim 12, wherein said desired shape has an
unconfined compressive strength of greater than 1000 kPa before a
pyrolysis treatment when measured by an unconfined strength test
protocol.
19. The conglomerate of claim 12, wherein said desired shape has an
unconfined compressive strength of greater than 1000 kPa after a
pyrolysis treatment at 900.degree. C. when pyrolyzed per a vertical
furnace pyrolysis protocol and measured by an unconfined
compressive strength protocol.
20. The conglomerate of claim 12, wherein said desired shape has an
unconfined compressive strength of greater than 500 kPa after a
pyrolysis treatment at 1400.degree. C. when pyrolyzed per a
horizontal furnace pyrolysis protocol and measured by an unconfined
compressive strength protocol.
21. The conglomerate of claim 12, wherein said desired shape has
75% remaining weight after drop testing per a drop testing
protocol.
22. The conglomerate of claim 12, wherein said desired shape has a
storage modulus greater than 150 MPa at 450.degree. C. when
measured in accordance with a dynamic mechanical analysis
protocol.
23. The conglomerate of claim 12, wherein said desired shape
distorts at least 14 mm before failure when measured by a hot
distortion test protocol.
24. The conglomerate of claim 12, wherein said desired shape
distorts less than 4 mm in 20 seconds when measured by a hot
distortion test protocol.
25. The conglomerate of claim 12, wherein said desired shape erodes
less than 0.02 cm per kg molten iron poured when measured by a
molten iron erosion test protocol.
26. A conglomerate comprising: silica sand and a binder material;
said binder material having an organic component, said organic
component being less than about 1% by dry mass of said
conglomerate; wherein said conglomerate distorts less than 10 mm in
100 seconds and distorts at least 14 mm before failure when
measured by a hot distortion test protocol.
27. A conglomerate comprising: a plurality of coal particles and a
binder material; said binder material having a biomass component,
said biomass component being between 1 and 10% by dry mass of said
conglomerate; wherein said conglomerate has an unconfined
compressive strength greater than 3000 kPa after pyrolysis at
900.degree. C. when measure by an unconfined compressive strength
protocol and pyrolyzed by a vertical furnace pryrolysis
protocol.
28. A conglomerate comprising: silica sand and a binder material,
said binder material having an organic component, said organic
component being about 1% by dry mass of said conglomerate; wherein
said conglomerate distorts less than 10 mm in 50 seconds and
distorts at least 14 mm before failure when measured by a hot
distortion test protocol; and wherein within a temperature range
between 50.degree. C. and 900.degree. C. said conglomerate releases
less than about 0.00008 nA response attributed to benzene when
compared to a 50-900.degree. C. benzene baseline value, or said
conglomerate releases less than about 0.000015 nA response
attributed to xylene when compared to a 50-900.degree. C. xylene
baseline value, or said conglomerate releases less than about
0.000008 nA response attributed to phenol when compared to a
50-900.degree. C. phenol baseline value when measured by a TGA-MS
protocol.
29. A conglomerate comprising: silica sand and a binder material,
said binder material having an organic component, said organic
component being about 1% by dry mass of said conglomerate; wherein
said conglomerate distorts less than 10 mm in 50 seconds and
distorts at least 14 mm before failure when measured by a hot
distortion test protocol; and wherein said conglomerate has a
reduction in benzene of at least 60%, a reduction in xylene of at
least 60% and/or a reduction in phenol of at least 50% compared to
benzene, xylene and/or phenol emissions from a silica sand and
phenolic urethane binder material when measured using a TGA-MS
protocol.
30. A process for making a conglomerate from a composite material,
the process comprising: providing a plurality of particles;
providing a binder material having a first component and a second
component, the first component containing an organic substance
selected from a group consisting of a collagen and a lignin, and
the second component containing an inorganic substance selected
from a group consisting of an element and an inorganic compound.
mixing the plurality of particles with the binder material to make
a conglomerate mixture; forming the conglomerate mixture into a
desired shape; and drying the desired shape.
31. The process of claim 30, wherein the binder material includes
an aqueous liquid.
32. The process of claim 31, further including pre-heating the
binder material before mixing with the plurality of particles.
33. The process of claim 30, wherein the binder includes a
saccharide.
34. The process of claim 30, further including exposing the desired
shape to ultraviolet radiation.
35. The process of claim 30, wherein the plurality of particles are
silica sand particles and the desired shape is a sand casting
core.
36. The process of claim 30, wherein the plurality of particles are
anthracite fines particles and the desired shape is fuel
pellet.
37. The process of claim 30, wherein the desired shape has a
plurality of silicon nanowires when pyrolyzed above 1200.degree. C.
per a horizontal furnace pyrolysis protocol.
38. The process of claim 30, wherein the desired shape has an
unconfined compressive strength of greater than 1000 kPa before
pyrolysis when measured by an unconfined compressive strength test
protocol.
39. The process of claim 30, wherein the desired shape has an
unconfined compressive strength of greater than 1000 kPa after
pyrolysis at 900.degree. C. using a vertical tube furnace protocol
and when measured by an unconfined compressive strength test
protocol.
40. The process of claim 30, wherein the desired shape has an
unconfined compressive strength of greater than about 500 kPa after
pyrolysis at 1400.degree. C. using a horizontal tube furnace
protocol and when measured by an unconfined compressive strength
test protocol.
41. The process of claim 30, wherein the desired shape before
pyrolyis has 75% remaining weight after drop testing per a drop
testing protocol.
42. The process of claim 30, wherein the desired shape has a
storage modulus greater than 150 MPa at 450.degree. C. when
measured by a dynamic mechanical analysis protocol.
43. The process of claim 30, wherein the binder material has a heat
flow between -0.5 and -2.5 Watts per gram for temperatures between
50 to 450.degree. C. as measured by a differential scanning
calorimetry protocol.
44. The process of claim 30, wherein the desired shape distorts at
least 14 mm before failure when measured by a hot distortion test
protocol.
45. The process of claim 30, wherein the desired shape distorts
less than 4 mm in 20 seconds when measured by a hot distortion test
protocol.
46. The process of claim 30, wherein the desired shape erodes less
than 0.02 cm per kg molten iron poured when measured by a molten
iron erosion test protocol.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a binder system for binding
particles together, and in particular, to binding system containing
a collagen or lignin and an inorganic material.
BACKGROUND OF THE INVENTION
[0002] The price increase of energy sources and raw materials in
recent years is known. For example, iron foundries with cupola
furnaces use foundry coke as a conventional fuel and the price of
the foundry coke increased by about 450% from the year 2002 to
2008. FIG. 1 illustrates a simplified scheme of a typical cupola
furnace used to continuously melt/make cast iron. At the start of a
production run, the cupola is filled with layers of coke and
ignited. After the coke is ignited, a strong air flow is introduced
to the coke bed through tuyeres and solid pieces of metal, e.g.
scrap iron, are charged into the furnace through a charging door
once a desired temperature is achieved. The solid pieces of metal
are alternated with additional layers of fresh coke, and limestone
is added as a flux. Silicon is also added and reacts with carbon to
form silicon carbide which can improve cast iron quality.
[0003] In typical iron cupola furnaces, for every 1000 pounds of
scrap iron charged into the furnace, approximately 100 pounds of
coke, 1 pound of silicon, 20 pounds of limestone, along with other
additives, are added or charged into the furnace[1]. The overall
dwell time for charged materials is typically 40-80 minutes which
avails about 20-40 minutes in a preheat zone where the material
experiences temperatures in the range of 1200-1400.degree. C. in a
reducing/starved-air (pyrolysis) environment.
[0004] Before coke is provided to the cupola furnace, it is
produced by pyrolysis of special coking bituminous coals [2-4].
Once produced, the coke has desirable chemical and physical
properties suitable for burning in the cupola furnace. For example,
the coke has a fused porous carbon structure that affords for a
fast burning fuel bed to be developed above the molten iron within
the cupola furnace[4].
[0005] One draw back from using foundry coke is the fact that only
a small fraction of mineable coal resources offer desirable coking
properties. In addition, the manufacture of coke consumes large
amounts of energy. As such, research on a coking replacement has
been conducted, but as of yet achieved limited success, and coke is
still the most used fuel in cupola furnaces.
[0006] It is of interest to note that before the development of
coke, anthracite was widely used as a fuel source in cupola
furnaces. Anthracite offers similar chemical properties as coke,
however, the combustion rate of chunks or pellets of anthracite is
relatively slow due to the materials condensed structure. The
combustion rate of anthracite chunks can be increased by reducing
chunk size[1], however if anthracite pieces become too small, they
can be blown out of the furnace via the strong tuyere air flow
before adequate or complete combustion can occur. Indeed, there are
minimum size specifications for solid fuels used in iron cupola
furnaces.
[0007] As such, anthracite fines represent a heretofor unusable
residue from anthracite mining processes and are often left as
waste in collection ponds, valleys, etc., of coal mining regions.
Although organic binders have been used to bind anthracite fines
into bricks, heretofor developed or employed organic binders have
not been able to survive the high temperature conditions in the
cupola furnace. Therefore, there is a need for a binder to bind
particles such as anthracite fines, to make pellets, bricks, and
the like such that the pellets, bricks, etc., can withstand high
temperatures and mechanical forces experienced in cupola
furnaces.
[0008] In addition to the need for a foundry coke alternative, the
metal casting industry extensively uses sand molds and sand cores
made from silica sand and organic binders, with conventional
binders used for the manufacture of sand cores emitting up to 70%
of a foundry's Volatile Organic Compound (VOC) emissions[5].
[0009] A sand core can containing between 1 to 3% of a binder with
the remaining portion being sand. The binder must provide a core
with adequate strength at room temperature and structural integrity
when exposed to molten metal. Paradoxically, after withstanding
molten metal thermal exposure and subsequent cooling, the binder
must then breakdown during shake-out so that the sand can be easily
removed from cavities of a cast product.
[0010] Several petroleum based binder systems in use today, such as
phenolic urethanes and furans, provide the desired structural
integrity, shakeout propensity and casting quality. However, the
phenolic urethane and furan binders breakdown after metal
solidification and can emit between 30 to 70% of a foundry's VOC's
and Hazardous Air Pollutants (HAP's) [5,6]. Furthermore, VOC and
HAP emissions increase proportionately with an increase in
core-loading[5,7,8].
[0011] Researchers have shown that VOC emissions for a collagen
core binder are 70-95% less than for a phenolic urethane
binder[6,9]. Collagen, which is available in large quantities as a
by-product of the meat-packing industry, is a fibrous triple
helical protein that strengthens skin, tendon and bones, and has a
tensile strength greater than steel. However, despite significant
emission reductions enabled by collagen, the material has been
marginally employed in foundries due to its inability to withstand
high temperatures imparted by molten iron (1290.degree.
C.-1510.degree. C.) at the molten metal/sand interface.
Specifically, breakdown of collagen at high temperatures results in
erosion of the core and costly casting defects. As such, there is
also a need for a binder for sand cores that can withstand the
harsh environment of metal casting and yet has lower VOC emission
in comparison to phenolic urethanes and furans.
SUMMARY OF THE INVENTION
[0012] The present invention discloses a binder material for
binding a plurality of particles together to form a conglomerate
such as a carbon-containing briquette, a sand casting core and the
like. The binder material can include a first component that can
contain a collagen and/or lignin and a second component that can
contain a metal, a metalloid and/or an inorganic compound. In some
instances, the binder material can be used to make a composite
material. The composite material can include the plurality of
particles and the binder material. The binder material affords for
the plurality of particles to be bound together into a desired
shape, the desired shape having desirable properties for a
particular use of the composite material.
[0013] The plurality of particles can be a plurality of sand
particles, i.e. grains of sand, or in the alternative, a plurality
of carbon-containing particles such as coal particles, coke
particles, anthracite fines, anthracite fines that have been ground
into a powder, and the like. The plurality of sand particles can be
bound together to form a casting component, for example a sand
casting core, a sand casting mold, etc. The plurality of
carbon-containing particles can be bound together to form a fuel
pellet which may or may not have a plurality of silicon carbide
nanowires as part of the fuel pellet structure/morphology. In some
instances, silicon carbide nanowires nucleate and grow when the
fuel pellet is heated above 1200.degree. C. in a reducing and/or
pyrolysis gaseous atmosphere.
[0014] The first component can contain denatured collagen and the
second component can contain inorganic particles such as particles
of an amorphous silica-rich ash, silicate, ferrosilicon, silicon,
combinations thereof and the like. In the event that the particles
include a silicate, the silicate can be an alkaline metal silicate,
alkaline earth metal silicate, combinations thereof, etc. In some
instances, the second component provides a source of silicon which
can react with the carbon-containing particles to form silicon
carbide, which may or may not be in the form of nanowires. In
addition, the nanowires can assist in binding of the plurality of
component particles together to form the component. The binder
material can also include an organic component, e.g. a biomatieral
and/or a carbohydrate. The carbohydrate can be a saccharide which
may or may not include a monosaccharide such as glucose, fructose,
galactose, xylose, ribose, etc.
[0015] A process for making a conglomerate using the binder system
can include mixing the plurality of particles with the binder
material and forming or molding the mixture into a desired shape.
In some instances, the binder material is pre-heated before mixing
with the plurality of particles. Thereafter, the desired shape can
be dried and may or may not be exposed to ultraviolet radiation
that can assist in curing of the shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic illustration of a cupola furnace;
[0017] FIG. 2 is graph of unconfined compressive strengths for
briquettes pyrolyzed at 900.degree. C. for 30 minutes and made from
100 g anthracite, 2 g collagen, 0 or 10 g silicon metal powder and
0 to 10 g lignin (plus water); Lignin A=hardwood lignin
precipitated from Kraft black liquor via sulfuric acid addition;
Lignin B=hardwood lignin extracted via Lignoboost.TM. process; and
Lignin C=Sigma Aldrich low sulfonate lignin;
[0018] FIG. 3 is a plurality of x-ray diffraction (XRD) plots for
various anthracite pellet materials before and after being subject
to a pyrolysis treatment at 1400.degree. C.;
[0019] FIG. 4 is a plurality of scanning electron microscopy (SEM)
images for: (a,b) collagen+kaolinite bindered anthracite fines;
(c,d) collagen+sodium silicate bindered anthracite fines; and (e,f)
collagen+silicon powder bindered anthracite fines;
[0020] FIG. 5 is a transmission electron microscopy (TEM) image of
a silicon carbide nanowire;
[0021] FIG. 6 is a graphical representation of unconfined
compressive strength for anthracite pellets as a function of pellet
composition;
[0022] FIG. 7 is a plurality of SEM images for collagen+silicon
powder bindered anthracite pellets made with: (a,c) original
anthracite fines; and (b,c) anthracite powder;
[0023] FIG. 8 is a schematic illustration of the cupola furnace in
FIG. 1 illustrating full scale testing of anthracite pellets made
according to an embodiment of the present invention;
[0024] FIG. 9 is graphical representation of percent mass retained
as a function of temperature for different binders subjected to
thermal gravimetric analysis (TGA) testing;
[0025] FIG. 10 is a graphical representation of TGA-mass
spectroscopy (TGA-MS) data for the detection of NO.sub.2 as a
function of temperature for three different binder materials:
collagen; phenolic urethane; and collagen+Li/K silicate;
[0026] FIG. 11 is a graphical representation of TGA-MS data for the
detection of benzene as a function of temperature for three
different binder materials: collagen; phenolic urethane; and
collagen+Li/K silicate;
[0027] FIG. 12 is a graphical representation of TGA-MS data for the
detection of phenol as a function of temperature for three
different binder materials: collagen; phenolic urethane; and
collagen+Li/K silicate;
[0028] FIG. 13 is a graphical representation of TGA-MS data for the
detection of xylene as a function of temperature for three
different binder materials: collagen; phenolic urethane; and
collagen+Li/K silicate;
[0029] FIG. 14 is a graphical representation of storage modulus as
a function of temperature for various binder materials;
[0030] FIG. 15 is a graphical representation of tan delta as a
function of temperature for various binder materials; and
[0031] FIG. 16 is a graphical representation of deflection as a
function of temperature for different bindered silica sand cores
subjected to hot distortion testing.
DETAILED DESCRIPTION OF THE INVENTION
[0032] The present invention discloses a binder system, also
referred to as a binder material or simply as a binder, for binding
together particles such as anthracite fines, silica sand grains,
and the like. As such, the present invention has utility for making
a conglomerate such as a carbon-base briquette or a sand casting
core. For the purposes of the present invention, the term
conglomerate is defined as shape, part, tool and the like made from
at least two different materials, wherein the materials adhere to
one another. The carbon-containing pellet can be used as a fuel
source in a cupola foundry furnace, a steel making blast furnace
and the like, or in the alternative, the sand casting core can be
used in a molten metal casting process. For the purposes of the
present invention, conglomerate and composite material are used
interchangeably. In addition, conglomerates include cores, sand
casting cores, carbon-containing briquettes, briquettes, pellets,
and bricks. The terms cores and sand casting cores are used
interchangeably, as are the terms carbon-containing briquettes,
briquettes, pellets, and bricks.
[0033] The binder material can include a first component that can
contain collagen and/or lignin and a second component that can
contain a metal, a metalloid and/or an inorganic compound. The
collagen may or may not be denatured and can be mixed with an
aqueous solution that can further be mixed with the second
component and/or a plurality of component particles. Other
additives can be included in the binder material, for example and
for illustrative purposes only, organic compounds that include
biomass, biomass derived material, carbohydrates such as
saccharides, monosaccharides and the like. For the purposes of the
present invention, the term biomass is defined as living or dead
vegetation or vegetation derived matter, animal, and/or animal
derived material, excluding petroleum and petroleum products.
[0034] The binder material can be mixed with a plurality of
particles to make a composite material that can be formed and/or
molded together into a conglomerate having a desired shape, the
conglomerate having desirable properties. For example and for
illustrative purposes only, the conglomerate can be a fuel
briquette or brick, also referred to as a fuel pellet herein, that
can be used in a cupola furnace. The fuel pellet can be made from a
mixture of the binder material and waste anthracite fines, and the
pellet can replace at least part of the foundry coke used by the
cupola furnace. The fuel pellet can also exhibit mechanical
properties that afford for the pellet to be stored, shipped and/or
fed into an industrial cupola furnace without excessive breakage
and/or burning.
[0035] The plurality of particles used to make the conglomerate can
have different shapes, sizes, chemical compositions, mechanical
properties and the like. In some instances, 50% by weight or mass
of the plurality of particles bindered by the binding material in
order to make a conglomerate have an average mean diameter of less
than 0.25 inches. In other instances, the plurality of particles
are sand particles that have an American Foundry Society (AFS)
grain fineness number between 25 and 150, inclusive.
[0036] The conglomerate can also be a sand casting core made from
the binder material and a plurality of sand grains/particles. The
sand core can exhibit adequate and/or desired high temperature
strength, liquid metal erosion resistance and shake-out qualities.
In addition, the sand core can exhibit or provide a significant
reduction in volatile organic compounds (VOC) emissions and
hazardous air pollutants (HAP) when compared to traditional binders
such as a phenolic urethane, furan, etc.
[0037] The second component can contain a silicate, ferrosilicon,
silicon, combinations thereof and the like. In the event that the
second component contains a silicate, the silicate can be an
alkaline metal silicate, alkaline earth metal silicate, an
amorphous silica-rich ash and combinations thereof. For example and
illustrative purposes only, the silicate can be sodium silicate,
potassium silicate, lithium silicate, magnesium silicate, calcium
silicate, kaolinite, and combinations thereof. In addition, the
amorphous silica-rich ash as can be an ash derived from rice hulls
and rice stalks. In some instances, the second component provides a
source of silicon which can react with carbon-containing particles
and form silicon carbide, which may or may not be in the form of
nanowires. In addition, the nanowires can assist in binding of the
plurality of particles together to form the conglomerate and
provide desirable mechanical properties thereto.
[0038] A process for making a conglomerate using the binder system
can include mixing the plurality of particles with the binder
material and forming or molding the mixture into a conglomerate
having a desired shape. In some instances, the binder material is
pre-heated before mixing with the plurality of particles.
Thereafter, the conglomerate can be dried and may or may not be
exposed to ultraviolet radiation that may assist in curing of the
conglomerate.
[0039] In order to better teach and/or disclose the present
invention, and yet in no way limit the scope thereof, examples of
at least two embodiments are provided below.
Manufacture and Testing of Fuel Pellets
[0040] Number 5 (#5) anthracite fines (hereafter referred to simply
as "anthracite fines") were obtained from Jeddo Coal Company
located in Wilkes-Barre, Pa. A sieve analysis of the anthracite
fines illustrated a particle size between US mesh # 10-80 (2000 to
177 .mu.m). In some instances, the anthracite fines were crushed
into powders that could pass through a U.S. mesh #100 (150 .mu.m)
sieve (hereafter referred to as "anthracite powder").
[0041] Chemical analysis and heat content of the anthracite fines
were compared with a typical foundry coke used by Ward
Manufacturing in Blossburg, Pa., with results shown in Table 1
below. As shown in the table, the dry heat content of the
anthracite fines was approximately the same as for foundry
coke.
TABLE-US-00001 TABLE 1 Proximate analysis % Heat Volatile Fixed
Ultimate analysis % (ash free) content Name matter Carbon Ash C H N
S O (mJ/kg) Anthracite 4.99 82.3 12.8 94.3 2.25 0.89 0.38 2.59
29.88 Coke 1.30 90.81 7.89 96.1 0.75 1.61 0.68 0.95 30.74
[0042] A dry granular collagen-based binder was provided by
Entelechy, representing Hormel Foods Company in Austin, Minn.
Fructose (98%-102%) was obtained from Mallinckrodt Baker, Inc., in
Phillipsburg, N.J.
[0043] Three different lignins were acquired and tested. The first
lignin was low sulfonate alkali lignin purchased from
Sigma-Aldrich, the second was a hardwood lignin extracted from
Kraft black liquor via sulfuric acid precipitation, and the third
was a hardwood lignin extracted via the Lignoboost.TM. process
which extracts lignin from black liquor in part by lowering the pH
of the liquor with CO.sub.2.
[0044] Three forms of silicon having three different redox levels
were obtained and tested. Metallic silicon (Si) having zero valence
and in the form of 10 cm or less lumps was purchased from Alfa
Aesar in Ward Hill, Mass. The lumps were crushed into powders of
less than #100 mesh before being mixed with the anthracite fines
and/or anthracite powder. Amorphous Si having +4 valence and in the
form of a sodium silicate (Na.sub.2SiO.sub.3) solution containing
42.5% by weight of dry solids was provided by J.B. DeVenne Inc., in
Berea, Ohio. And crystallized Si having +4 valence in the form of
kaolinite powder (KGa-1, Al.sub.2Si.sub.2O.sub.5(OH).sub.4) was
obtained from Washington County, Ga.
[0045] The anthracite fines were dried at 105.degree. C. overnight
to remove moisture and 1 g of collagen binder was dissolved in 12 g
of water at 70.degree. C. to form a gelatin solution. In some
instances, fructose was added and dissolved in the water plus
collagen binder solution. A Si source, either the metallic Si or
the kaolinite powder, was mixed with the anthracite fines, or in
the alternative, the Si-containing liquid solution (sodium
silicate) was added to the gelatin solution. Thereafter, the
anthracite fines, with or without the Si source depending on which
form of Si was being used, were mixed with the gelatin solution
without or with the Si-containing liquid solution, respectively.
The final mixture of anthracite fines and gelatin solution was then
packed into a cylindrical mold (2.86 cm diameter.times.4.76 cm
long) with 275 kPa (40 psi) pressure applied on both ends. Finally,
a conglomerate in the form of a pellet was extruded from the mold
and cured under ambient conditions with at least three anthracite
pellets produced from a single batch or final mixture. During
curing, evaporation released approximately 10 g of the initial 12 g
of water.
[0046] Mechanical strength of the pellets at room temperature was
determined using unconfined compressive strength testing and drop
shatter testing[10]. The unconfined compressive strength of
anthracite pellets was determined using a Simpson-Gerosa electronic
universal sand strength machine. A horizontally moving arm applied
pressure on a pellet until failure. Final compressive force was
calculated based on the diameter of the original pellet sample,
assuming negligible shape change during the test. The sample
preparation and unconfined compressive strength procedure disclosed
herein are defined as an unconfined compressive strength test
protocol.
[0047] The drop shatter test was a standard breakage test used for
foundry coke with results often referred to as an anti-breakage
strength. The anthracite pellets were dropped onto a steel plate
through a 1.83 meter (m) long polyvinylchloride (PVC) tube that had
an inner diameter of 3.8 cm. A total of 10 drops for each pellet
was performed with a first end of the pellet pointing in the down
direction for a given drop, followed by a second end of the pellet
pointing in the down direction for the next drop. After the tenth
and final drop, the weight of the largest remaining piece of the
pellet was obtained. In addition, if no single piece having a mass
larger than 50% of the original weight of the pellet remained after
a drop, the test was stopped and 0% was recorded for the test. The
sample preparation and drop testing procedure disclosed herein are
defined as a drop test protocol.
[0048] Pyrolysis of the anthracite pellets was conducted in a
horizontal tube furnace or a vertical tube furnace. When using the
horizontal tube furnace, a pellet was placed in an alumina tube
extending through the furnace and a slow nitrogen gas flow of
approximately 2 standard cubic centimeters per minute was used to
prevent the anthracite from burning. In addition, a three-step
pyrolysis procedure was employed with the furnace ramped at
3.degree. C./min up to 1400.degree. C., holding at 1400.degree. C.
for 2 hours, and then furnace cooling to room temperature at
3.degree. C./min. The pyrolyzed anthracite pellets were then
removed from the tube-furnace for further tests. Unless otherwise
identified, the prescribed maximum temperature was 1400.degree. C.,
which is generally close to preheating zone temperatures of a
cupola furnace. This pyrolysis procedure is defined as a horizontal
furnace pyrolysis protocol.
[0049] For pyrolysis in the vertical tube furnace, the furnace was
heated to a predefined temperature with a laminar flow of nitrogen
gas provided up through a vertical alumina tube extending through
the furnace. Thereafter, a 5 g sample was placed in a basket and
descended into the heated tube. A thermocouple was used to record
the temperature of the region where the sample was located and it
was determined that the sample region increased from 30-40.degree.
C. to 800.degree. C. within about 2-3 minutes, where the
temperature remained for the prescribed time. This pyrolysis
procedure is defined as a vertical furnace pyrolysis protocol.
[0050] Burning rates for the anthracite fines and foundry coke were
determined by measuring the time required for complete combustion
of approximate 5 g pieces of anthracite pellets and foundry coke.
Specifically, a piece of an anthracite pellet or foundry coke was
placed in a 5 cm diameter quartz tube furnace and heated to
1050.degree. C. under an inert and/or reducing atmosphere.
Thereafter, the piece was held at 1050.degree. C. within the tube
for between 2-3 minutes and then air at about 2 L/s was passed up
through the tube and into contact with the material. The air thus
provided oxygen for burning of the piece and a time was recorded
for when combustion was no longer observed.
[0051] Scanning electron microscopy (SEM) analysis was performed
using a FEI Quanta 200 Environmental SEM with a Gaseous SE
detector, a voltage of 20 kV and an electron beam spot size of 4
nm. A transmission electron microscope (TEM, Model 2010, JEOL,
Tokyo, Japan) was also used to determine material morphology,
particle size and electron diffraction.
[0052] Ambient temperature XRD patterns were obtained using a
PANalytical X'Pert Pro MPD diffractometer and powders of the
anthracite pellets were obtained by crushing a pellet with a ball
mill. It is appreciated that the XRD patterns provided a bulk
measurement of the material.
[0053] Anthracite pellets were prepared with an array of
compositions and protocols. For example, anthracite pellet
compositions included 100 g of anthracite fines, 1 g of collagen, 0
to 1 g of fructose, 0 to 10 g lignin and 0 to 10 g of silicon,
kaolinite or sodium silicate. Results of unconfined compressive
strength tests as described above for anthracite pellets having
different compositions, excluding lignin, are shown in Table 2
below. As shown by the data in the table, the use of collagen
and/or fructose as a binder material provides strength to the
pellets before pyrolysis and as such can provide strength at lower
temperatures that would be experienced by anthracite pellets during
shipping, storage and/or initially entering a cupola furnace. The
data also show that pellets made with 10 g silicon metal powder
achieved the most favorable unconfined compressive strengths: 1300
kPa before pyrolysis and 690 kPa after pyrolysis. In addition, 1%
fructose increased the strength of 10 g silicon powder pellets even
more. In contrast, the 10 g sodium silicate addition offered
considerable unconfined compressive strength (2344 kPa) before
pyrolysis, but only 28 kPa after pyrolysis. Pellets made with
kaolinite exhibited negligible strength after pyrolysis. It is of
interest to note that for all three Si sources, less Si
corresponded to lower strengths.
TABLE-US-00002 TABLE 2 Unconfined Drop shatter Unconfined
compressive remaining compressive Carbon strength before before
strength after Source Other additives pyrolysis (kPa) pyrolysis (%)
pyrolysis (kPa) 100 g No other additives 1234 76 0 anthracite 1 g
fructose 1095 99 0 fines + 1 g 3 g sodium silicate N/D 90 0
collagen (0.7 g as silicon) 6 g sodium silicate 2455 99 0 (1.4 g as
silicon) 10 g sodium silicate 2342 98 ~28 (2.3 g as silicon) 1 g
kaolinite N/D 91 0 (0.22 g as silicon) 10 g kaolinite 1340 93 ~7
(2.2 g as silicon) 2 g silicon 1230 77 69 5 g silicon N/D 80 345 10
g silicon 1250 91 690 1 g fructose, 1300 99 720 10 g silicon
Foundry No additives 2758 93 2758 Coke
[0054] Regarding the addition of lignin to the binder material,
FIG. 2 is a graph of unconfined compressive strengths determined by
the unconfined compressive strength protocol for briquettes
pyrolyzed at 900.degree. C. for 30 minutes and made from 100 g
anthracite, 2 g collagen, 0 or 10 g silicon metal powder and 0 to
10 g lignin (plus water). Regarding the legend in FIG. 2, Lignin A
was the hardwood lignin extracted from Kraft black liquor via
sulfuric acid precipitation, Lignin B was the hardwood lignin
extracted via the Lignoboost.TM. process and Lignin C was the low
sulfonate alkali lignin purchased from Sigma-Aldrich. The figure
illustrates that higher lignin amounts yield higher unconfined
compressive strengths, even without the presence of silicon, in an
intermediate temperature range that would be experienced for
anthracite pellets fed into a cupola furnace. It is appreciated
that foundry coke has an unconfined compressive strength of about
300 psi, thus further illustrating improved binding with the use or
addition of lignin.
[0055] Looking now at FIG. 3, XRD patterns illustrate a crystal
structure change within the anthracite pellets induced by pyrolysis
at 1400.degree. C. The raw anthracite fines, i.e. before pyrolysis,
contained muscovite [KAl.sub.2(AlSi.sub.3O.sub.10)(F,OH).sub.2],
kaolinite, and quartz (SiO.sub.2) (FIG. 3a). The presence of
crystallized Si (+4 valence) was also detected. After pyrolysis,
muscovite and kaolinite were converted into mullite
(Al.sub.6Si.sub.2O.sub.13), and the carbon became more crystallized
as evidenced by a sharper hump or peak between 2 theta of
20.degree. and 30.degree.. Pyrolysis of the anthracite fines alone
yielded no silicon carbide.
[0056] When 10 g of kaolinite powder was bindered to 100 g
anthracite fines with 1 g of collagen, the kaolinite XRD peaks that
appeared before pyrolysis were converted mostly to mullite. This
kaolinite-anthracite combination also did not yield silicon
carbide.
[0057] In contrast, when collagen bindered anthracite fines
included sodium silicate as the Si source, pyrolysis of the
material yielded beta silicon carbide (3C--SiC) (FIG. 3f). In
addition, the pyrolysis resulted in a net-reduction of Si (+4)
valence and a net increase of Si (0) valence. It is appreciated
that the amorphous structure of the sodium silicate may have
enhanced the kinetics of this redox reaction.
[0058] The formation of SiC increased when 10 g of silicon metal
powder was bindered to 100 g anthracite fines with 1 g of collagen
and pyrolyzed (FIGS. 3g & 3h). In particular, after pyrolysis
the silicon metal XRD peaks were significantly reduced while very
strong diffraction peaks for the cubic crystal structure of 3C--SiC
were observed. As such, zero valence silicon and carbon reacted
with each other to form silicon carbide during pyrolysis of the
material.
[0059] Turning now to FIG. 4, SEM images of anthracite pellet
morphology after pyrolyis at 1400.degree. C. and as a function of
the different Si-containing additives are shown. For the
kaolinite-anthracite system (FIG. 4a), the kaolinite powders were
sintered into larger ceramic features that spanned across
neighboring anthracite particles. A higher magnification of the
anthracite pellet surface (FIG. 4b) illustrates numerous spheres
were generated from the transformation of kaolinite to mullite plus
silica. In addition, the spherical shapes indicated that the
transformed kaolinite to mullite plus silica was liquid and
exhibited a low adhesive force with the anthracite surface.
[0060] When sodium silicate was the additive, the pyrolyzed
products exhibited sponge-like ceramic structures (FIGS. 4c &
4d) that were similar to the sodium silicate precursor structure.
The ceramic structure was not composed of silicon carbide, as
indicated by the EDS spectrum inset in FIG. 4d, although some SiC
was present within the pyrolyzed anthracite-sodium silicate. The
presence of silicon carbide nanowires (SCNWs) was not observed.
[0061] In contrast, the 10 g silicon powder additive resulted in a
labyrinth of SCNWs. The nanowires were generally 20 .mu.m in length
with lengths up to 100 .mu.m observed. Per visual inspection, the
nanowires altered the color of the pellets from the black of
anthracite to the light green of the nanowires. In addition, the
SCNWs were observed to have formed after heating of the anthracite
pellet above 1200.degree. C. for times as low as 6 minutes and as
such can provide improved strength at higher temperatures that
would experienced by anthracite pellets fed into a cupola furnace.
As such, the SCNWs were formed and/or present when the anthracite
pellets were pyrolized above 500.degree. C., e.g. above 900.degree.
C., 1000.degree. C., 1100.degree. C. and/or 1200.degree. C.
[0062] The nanowires were typically 20-50 nm in diameter and were
coated by an amorphous thin layer (about 2 nm thick) of silicon
oxide as shown in the high resolution TEM (HRTEM) image in FIG. 5.
The SCNWs were also highly crystallized and per the XRD pattern in
FIG. 3h, the silicon carbide was 3C--SiC which has a face centered
cubic structure. The space between two planes in FIG. 5 was about
0.25 nm which is concurrent with the calculated value for a 3C--SiC
crystal structure (0.251 nm). The stacking faults in FIG. 5
confirmed that the nanowires were grown by stacking of the (111)
lattice plane in the [111] direction.
[0063] The effect of anthracite particle size on anthracite pellet
binding strength was also examined. With a smaller particle size,
e.g. using anthracite powder to make a pellet, gaps between
anthracite particles were reduced and SiC nanowires were able span
between adjacent anthracite particles. FIG. 6 provides a graph
showing post-pyrolysis strength of anthracite pellets as a function
of pellet composition for pellets made with silicon powder and/or
anthracite powder. As shown in the graph, for a given silicon
content, anthracite pellets made from 100% anthracite powder
(<#100 mesh) could be as much as 5 times stronger than
anthracite pellets made from 100% anthracite fines (#10 to 80
mesh). In addition, post-pyrolysis strength of anthracite pellets
was enhanced by using a mixture of anthracite powder and anthracite
fines. For example, pellets made from 50% anthracite powder and 50%
anthracite fines were only slightly weaker than pellets made from
100% anthracite powder. The positive effect of using silicon powder
is also shown in FIG. 6.
[0064] SEM images in FIG. 7 illustrate the differences between
anthracite particle size. In particular, for anthracite pellets
made from 100% anthracite fines, relatively large void spaces
between the anthracite particles were observed (FIG. 7a) and the
SCNWs were not long enough to span from one anthracite grain to
another. As such, SCNWs could bind the anthracite particles only in
regions at or near touching points between adjacent particles
(FIGS. 7a & 7c). In contrast, pellets made from 100% anthracite
powder exhibited relatively small void spaces (FIG. 7b) and the
SCNWs spanned between adjacent particles (FIG. 7d). In addition,
even when anthracite pellets were made from 50% fines and 50%
powder, the smaller particles could fit within voids between the
larger particles and thereby reduce void space and afford for SCNWs
to span and/or bind adjacent particles.
[0065] Turning now to Table 3, a comparison of burning rates for
different compostion anthracite pellets and foundry coke at
1050.degree. C. is shown. It is appreciated from the data that
pieces of anthracite pellets had burn rates generally equivalent to
pieces of coke. In contrast, unbound anthracite fines burned
considerably faster.
TABLE-US-00003 TABLE 3 Sample Time for fully burn (min) Coke pieces
18.75, 19.5 Anthracite pellet pieces (100 g powdered 18.5, 17.5
anthracite, 4 g silicon, 1 collagen) Anthracite pellet pieces 22.3
(25 g powdered anthracite, 75 g anthracite fines, 10 g silicon, 1 g
collagen) Unbound anthracite fines (#10 .times. 80) 5.25, 4.5
[0066] Full scale testing of anthracite fine bricks made from
anthracite fines, collagen binder, fructose additive, and silicon
powders was performed by feeding the bricks into an industrial
foundry cupola. In total, 500 pounds of anthracite bricks generally
measuring 5.75 inches (14.6 cm) in diameter, 2.25 inches (5.7 cm)
in height and weighing 1.8 pounds (0.82 kg) were prepared.
[0067] The testing included feeding the bricks into the cupola for
about one hour at a rate that replaced 10% of the coke that would
have otherwise been used (FIG. 8). The anthracite bricks were
dropped about 10 feet into a hopper bucket along with scrap metal,
coke, silicon bricks, limestone, etc., and the hopper afforded for
the materials to be fed into the cupola. In addition, the feeding
rate of the silicon bricks was diminished by about 5-8% in order to
account for the silicon in the anthracite bricks.
[0068] When the anthracite bricks were dropped into the bucket, no
breakage was observed as per visual inspection. Breakage was also
not observed, as per remote video camera, when the bricks were
conveyed into the top of the cupola. As the anthracite bricks
descended through the cupola melt zone and past the tuyere windows,
10 to 12 shapes that exhibited a tell-tale smooth curvature of a 14
cm circle were observed and it appeared that a number of these
shapes were anthracite bricks. None of the bricks had broken into
pieces by the time they passed the tuyere windows and the bricks
appeared to be burning throughout their structure while in the melt
zone, as were chunks of coke.
[0069] The product or resulting metal quality and chemical
composition produced by the cupola furnace, along with cupola
temperatures and pressures, were analyzed during the full-scale
demonstration. The metal product quality and chemistry parameters
were within experimental error, although back pressure and
temperature (represented by the upper-stack temperature) of the
cupola increased slightly during the addition of the anthracite
bricks. It is appreciated that the increase in back pressure and
temperature could have resulted from the anthracite-silicon bricks
burning faster than the coke. However, it is also appreciated that
cupola operation is complicated and affected by many factors, and
as such, no conclusions could be drawn relating the changes in
temperature and back pressure to the addition of the anthracite
bricks.
Manufacture and Testing of Sand Casting Cores
[0070] Samples of binder material and sand casting cores made with
the binder material were prepared for thermogravimetric analysis
(TGA), dynamic mechanical analysis (DMA), differential scanning
calorimetry (DSC) and hot distortion testing (HDT). In general, TGA
and DSC samples contained no sand and were prepared with only the
binder components listed in Table 4. DMA and HDT samples were
prepared with sand and binder. DMA samples were molded into
gum-stick sized core samples generally measuring 12 mm.times.5
mm.times.35 mm and HDT samples were molded into candy bar sized
samples generally measuring 15.24 cm.times.2.54 cm.times.1.27
cm.
TABLE-US-00004 TABLE 4 Composition for Composition for Name TGA and
DSC Samples DMA and HDT Samples Sodium 10 g Modified Sodium 3 g
Solution, 100 g Sand Silicate Silicate Collagen 10 g Collagen, 30
mL Water 1 g Collagen, 100 g Sand C + K/Li 10 g Collagen, 8.7 g
K/Li 1 g Collagen, 0.87 g K/Li Silicate Silicate (solids content)
Silicate (solids), 100 g Sand C + Na 10 g Collagen, 8.5 g Na- 1 g
Collage, 0.85 g Na- Silicate Silicate (solids content) Silicate
(solids), 100 g Sand Phenolic 0.55 parts A, 0.45 parts B 1 g
Phenolic Urethane, Urethane 100 g Sand
[0071] A modified sodium silicate solution containing 42.5% by
weight of dry solids was provided by J.B. DeVenne and Associates in
Berea, Ohio. Collagen in the form of dry powder was provided by
Entelechy in Canton, Mich. A phenolic urethane binder that was heat
was provided by Ashland Chemical Company in Columbus, Ohio. The
phenolic urethane binder came as a two-part binder (Part A and Part
B) that cured when mixed and heated. Potassium silicate was
provided by PQ Corporation in Malvern, Pa. and came as a liquid
with 29% by weight solids content. Silica sand having a specified
American Foundry Society (AFS) AFS grain fineness number ranging
from 67-73 was provided by Wedron Silica Company in Wedron,
Ill.
[0072] In one embodiment of a binder material/system, 10 g of
collagen was added into 20 mL of modified sodium silicate with 5
grams of triglycerides, and the entire mixture was heated to
70.degree. C. and vigorously stirred for 5 minutes. The hybrid
mixture was then poured into an aluminum pan and dried at
110.degree. C. for 12 hours. Phenolic urethane samples were
prepared with 55 parts A to 45 parts B, as is common in industry
practice, and then dried at 110.degree. C. for 24 hours. Another
hybrid binder material was prepared by mixing 10 g collagen with
2.9 grams of K/Li silicate solids, the mixture also dried at
110.degree. C. for 12 hours.
[0073] For TGA tests, a small portion of dried binder (10 to 20 mg)
was removed with a scalpel and placed in a TA instruments SDT
2960--Simultaneous DSC-TGA instrument. The test commenced at room
temperature under an argon atmosphere and was heated at 10.degree.
C./min to 600.degree. C. Trials were tested in duplicate with an
average between the duplicates taken/used as final TGA results. The
sample preparation and TGA procedure disclosed herein are defined
as a TGA test protocol.
[0074] For DSC tests, binder samples were shaved and finely
powderized with a razor blade. DSC analyses used a 2.0 mg sample
and employed a TA Instruments TA-Q100 DSC instrument. A hermetic
pan was used to hold samples with the pan lid punctured with an 8
penny finish nail to prevent the pan from `jumping` from the
heating element during analysis. Samples were purged with nitrogen
gas at 50 mL/min. Two tests were performed using a temperature ramp
of 10.degree. C./min to 510.degree. C. A third test was performed
using a temperature ramp of 10.degree. C./min to 510.degree. C.,
followed by cooling at 20.degree. C./min to 50.degree. C. and then
ramping at 10.degree. C./min to 510.degree. C. a second time. The
sample preparation and DSC procedure disclosed herein are defined
as a DSC test protocol.
[0075] For DMA and HDT experiments, bindered cores were made by
mixing 1 to 3% binder material with 99 to 97% silica sand (Table
4). Bindered core samples were prepared by mixing 1.0 kg of washed
foundry silica sand with a given binder material for 90 seconds at
Level `2` Solid State Speed Control, in a Commercial Kitchen Aid
Mixer, Model Number KSMC50S.
[0076] For DMA analyses, the mixed material was hand packed into an
8-part wooden core mold that produced samples sizes described
above. Samples were then cured at 110.degree. C. for one hour, with
the exception of heat cured phenolic urethane bindered samples
which cured for 24 hours. The samples were then removed from the
core mold and placed in a dessicator for overnight storage.
[0077] TEA-cured phenolic urethane samples were provided by the
Penn State University HMAC foundry and were produced using 1.1%
phenolic urethane cured with TEA gas in a full-scale/industrial
operation. The cores of the samples had a 3 inch.times.1 inch
diameter rod protruding from a main core, which was removed and
manually filed down to a size that could be used for DMA
testing.
[0078] For DMA analyses, samples were analyzed using a TA
Instruments DMA q800 unit with a dual cantilever clamp. The samples
were heated at 10.degree. C./min to 500.degree. C., while a middle
support oscillated at a frequency of 20 Hz and a 5 .mu.m amplitude.
During testing, the samples were maintained under a nitrogen gas
atmosphere flowing at 2 L/min. The sample preparation and DMA
procedure disclosed herein are defined as a DMA test protocol.
[0079] For HDT analyses, samples were formed into hand packed cores
in a 16 sample wooden core box. The bindered cores were cured in
the core box at 110.degree. C. for 1 hour, with the exception of
phenolic urethane bindered cores which were cured for 24 hours.
[0080] The HDT was performed using a custom HDT device that clamped
2.54 cm of a first end portion of the sample onto an iron ledge.
The samples were then heated in the center of the exposed 12.7 cm
of the sample using a natural gas flame from a 2.54 cm perforated
Bunsen burner having an adiabatic flame temperature of 1960.degree.
C. and a micrometer detected deformation of the sample at a
location 1.27 cm from a second end of the sample. In addition, the
micrometer transmitted deformation readings every second to a
computer which logged the data. For each binder composition, 10 to
15 samples were analyzed. It is appreciated that the results
exhibited inherent variability in both time to given deflection and
deflection at failure. The sample preparation and HDT procedure
disclosed herein are defined as an HDT protocol.
[0081] Molten metal erosion testing was also performed on sand core
samples. The sand cores were produced with collagen, sodium
silicate, sodium silicate plus collagen, lithium silicate plus
collagen (two variations), heat cured phenolic urethane and TEA
cured phenolic urethane. The cores were hand packed and had a
general final size of 5 in. long.times.5 in. wide.times.2 in.
thick--with the exception of TEA cured phenolic urethane cores
which were 3 in. wide.times.2.75 in. thick. The cores were placed
on a stand leaning at a 45.degree. angle and molten iron at
2620-2720.degree. F. was poured onto the surface of the core from a
height of about 8 inches using a constant head core. After pouring
the molten metal over a core sample, the metal was captured in a
ladle and weighed. The sand cores were then removed and evaluated
for erosion and surface characterization.
[0082] Core evaluation was performed using core scratch hardness
and a micrometer to measure erosion depth. In addition, sand was
used to fill any eroded away region in order to quantify erosion
volume. The cores were evaluated for core hardness before and after
the pour with hardness measured one inch from where molten metal
flowed off the core. The erosion depth was measured using Mitutoyo
calipers and sand was poured into an erosion cavity, if present,
and scraped off using a metal bar. The quantity of sand required to
fill the cavity was then measured in order to quantify sand volume
eroded during metal pouring. The sample preparation and molten
metal erosion testing procedure disclosed herein is defined as an
molten metal erosion testing protocol.
[0083] Turning now to FIG. 9, core binder TGA data show the mass
retained by the tested binder material at high temperatures. The
inorganic sodium silicate retained the most mass up to the highest
temperatures (80% at 500.degree. C.) whereas collagen retained the
least mass (50% at 328.degree. C.) and phenolic urethane (heat
cured) retained 50% mass at 438.degree. C. It is appreciated that
the collagen+sodium silicate (50% mass loss at 646.degree. C.) and
collagen+K/Li silicate (50% mass loss at 600.degree. C.) binders
best reproduced or were closest to the mass loss exhibited by the
heat cured phenolic urethane.
[0084] In addition to mass retained, FIGS. 10-13 provide TGA-mass
spectrometry (TGA-MS) semi-quantitative NO.sub.2, benzene, phenol,
and xylene emission data, respectively, for three sand core
samples: one bindered with 1% Collagen; one bindered with 1%
phenolic urethane (TEA cured); and one bindered with 1%
Collagen+0.87% Li/K silicate.
[0085] The TGA-MS testing utilized a TA Instruments TGA 2050
coupled to a mass spectrometer (ThermoStar.TM. 301T, Pfeiffer
Vacuum) which measured the gaseous effluent. In addition, an
Ashland Isocure Focus(R) WTC Binder having 0.55 g of part 1 and
0.45 g part II per gram of binder was used as the phenolic urethane
binder. Conglomerate samples weighing 400 mg were used for the
TGA-MS testing and the samples contained approximately 1% organic
binder, dry mass basis. The samples were cured by conventional
processing technology and were not exposed to temperatures higher
than curing conditions. Once cured, a sample was placed in an
alumina pan which was subsequently placed in the TGA-MS furnace and
heated from room temperature to 1000.degree. C. at a rate of
10.degree. C./min. The furnace, and thus the sample, were purged
with 100% ultra-high purity argon gas for a minimum of one hour
prior to analysis and for the duration of analysis using a gas flow
rate of 90 mL/min.
[0086] The MS provided a response measured in nanoamps (nA) as a
function of temperature for each atomic mass unit (AMU) analyzed.
From the measured nA as a function of temperature data, a plot as
shown in FIG. 10-13 can be constructed. Thereafter, a straight line
is drawn between nA data corresponding to 50.degree. C. and
900.degree. C. This straight line is taken, and hereafter referred
to, as the baseline. A maximum response is generally visible from
the plot and measured and/or determined as the maximum nA value
less the baseline nA value at the temperature corresponding to the
maximum nA value.
[0087] The AMU responses for benzene were taken for an AMU of 78,
for phenol an AMU of 94 and for xylene an AMU of 106. As shown in
FIGS. 11-13, TGA-MS analysis of a collagen+K/Li silicate sample
provided a maximum response of 0.000007 nA for benzene, 0.000003 nA
for xylene and 0.000004 nA for phenol. In comparison TGA-MS
analysis of a TEA cured phenolic urethane sample provided a maximum
response of 0.000113 nA for benzene, 0.000031 nA for xylene and
0.000010 nA for phenol. As such, within a temperature range between
50.degree. C. and 900.degree. C. the collagen+K/Li silicate sample
and/or an inventive binder material disclosed herein mixed with
silica sand to produce a conglomerate can release less than about a
0.00008 nA response attributed to benzene when compared to a
50-900.degree. C. benzene baseline value, and/or less than about a
0.000015 nA response attributed to xylene when compared to a
50-900.degree. C. xylene baseline value, and/or less than about a
0.000008 nA response attributed to phenol when compared to a
50-900.degree. C. phenol baseline value.
[0088] As such, an inventive binder disclosed herein can provide a
reduction in benzene of at least 60%, a reduction in xylene of at
least 60% and/or a reduction in phenol of at least 50% compared to
the phenolic urethane tested herein. In the alternative, an
inventive binder can provide a reduction in benzene of at least
70%, a reduction in xylene of at least 70% and/or a reduction in
phenol of at least 60% compared to the phenolic urethane tested
herein. In still another alternative, an inventive binder can
provide a reduction in benzene of at least 80%, a reduction in
xylene of at least 80% and/or a reduction in phenol of at least 65%
compared to the phenolic urethane tested herein. In still yet
another alternative, an inventive binder can provide a reduction in
benzene of at least 90%, a reduction in xylene of at least 90%
and/or a reduction in phenol of at least 67.5% compared to the
phenolic urethane tested herein.
[0089] When conducting these analyses, the TGA-MS responses were
normalized by analyzing a standard sample of 27.9 mg calcium
oxalate. For this standard calcium oxalate sample, the maximum
response for AMU 44, attributed to CO.sub.2, was about 5 nA total
when compared to a baseline of 0 nA at about 800.degree. C. When
the nA response for calcium oxalate is different than this, the
test samples could be normalized accordingly. In addition, the
sample preparation and TGA-MS procedure disclosed herein are
defined as a TGA-MS protocol.
[0090] Each sample was heated in 100% argon at 10.degree. C./min to
1000.degree. C. with air emissions monitored via mass spectrometry.
As shown in the figures, collagen emits significantly less VOCs
than phenolic urethane. For example, FIG. 11 illustrates that
phenolic urethane emits over 35% more benzene than collagen at
temperatures around 580 to 600.degree. C. A significant reduction
in phenol and xylene emissions by collagen when compared to
phenolic urethane is also shown in FIGS. 12 and 13.
[0091] Regarding DMA testing, FIG. 14 illustrates that all the
binder systems have similar storage moduli at room temperature
(approximately 1500-2250 MPa). However, significant changes occur
with increased temperatures with phenolic urethane and sodium
silicate losing their stiffness at temperatures around 150 to
200.degree. C. In addition, collagen rapidly lost its stiffness at
250.degree. C. which corresponds to the temperature that Collagen
experiences significant mass loss (see FIG. 9).
[0092] Not being bound by theory, it is postulated that bindered
core DMA performance in the 300 to 500.degree. C. range correlates
to a bindered core's resistance to cracking-type failure which can
lead to erosion. As such, a higher storage modulus in this
temperature range corresponds to less failure. In that perspective,
collagen alone was the lowest performing material since it offered
the lowest storage modulus of 10-100 MPa in this range. Sodium
silicate was the highest performer at 400-900 MPa and phenolic
urethane (heat cured) was 50-100 MPa. The collagen+silicate binders
performed well with values between 50-300 MPa in the stated
temperature range. It is appreciated that the low storage modulus
for collagen in the temperature range of 275.degree. C. to
400.degree. C. may contribute to core erosion when the collagen is
exposed to molten metal.
[0093] Referring now to FIG. 15, a graph of DMA tan delta as a
function of temperature is shown. Tan delta is a unitless parameter
that corresponds with the tangent of the phase lag of material
response. This phase lag is defined as the ratio of modulus loss
(E.quadrature..quadrature.--the component of the modulus that has a
time-dependent or viscous response) to storage modulus
(E.quadrature.; which represents the elastic or instantaneous
response). As such, peaks in the tan delta versus temperature data
represent a sudden change in the time-dependent nature of response.
For polymers, this is typically interpreted as a glass
transition.
[0094] As shown in FIG. 15, the first peak temperature for collagen
was 262.degree. C., whereas the first peak for phenolic urethane
was 201.degree. C. The collagen's glass transition temperature was
262.degree. C. and it exhibited a very narrow tan delta peak which
would correspond to brittle behavior above this temperature.
Brittleness was in fact observed for all the samples after the DMA
testing. The phenolic urethane exhibited a glass transition at
201.degree. C. and both the collagen+silicate hybrids exhibited
glass transitions at approximately 260-270.degree. C. (FIG. 15 and
Table 3). It is appreciated that the collagen+silicate binder peaks
were relatively broad, and as such, the hybrid binders could offer
a more favorable thermal response when compared with phenolic
urethane.
TABLE-US-00005 TABLE 5 T(.degree. C.) for Storage Modulus Tan Delta
Storage System 300.degree. C. 450.degree. C. Peak T(.degree. C.)
Modulus <1400 MPa Collagen 21.62 98.63 0.75 263 250 Phenolic
188.9 70.21 0.38 201 100 Urethane (Heat Cured) Phenolic 52.8 45.5
0.31 230 X Urethane (TEA Cured) Sodium 362.4 682.6 0.63 273 180
Silicate Collagen + 71.7 163.9 0.36 262 n/a Sodium Silicate
Collagen + 54.3 163.9 0.47 258 n/a Li/K Silicate
[0095] HDT core samples distorted while being heated by the natural
gas flame with results shown by the graph in FIG. 16. The phenolic
urethane, sodium silicate and both collagen+silicate bindered cores
distorted to a maximum degree measurable with the instrument which
was 13.5 mm. In addition, the collagen bindered core was the only
core that did not reach the maximum distortion, but rather broke at
approximately 4 mm of distortion. It is appreciated that the
collagen+sodium silicate and collagen+lithium/potassium silicate
bindered cores required the longest time to reach maximum
distortion as shown in FIG. 16 and Table 6 below. It is also
appreciated that rapid distortion at high temperatures provides
unwanted core behavior, for example yielding casting defects. Thus
the ability of the collagen+sodium silicate and
collagen+lithium/potassium silicate bindered cores to withstand
thermal stress for the longest amount of time can be favorable.
TABLE-US-00006 Average Time Average Average Final to 1 mm
Distortion at Distortion Binder System Distortion (sec) Breaking
(mm) Time (sec) 1% Collagen 65.4 4.2 71.3 1% Heat Cured 50.1 13.5
84.5 Phenolic Urethane 1.28% Sodium 21.7 No break 30.3 Silicate
Collagen + Sodium 29.0 No break 197.4 Silicate Collagen + Li/K 83.4
No break 152.1 Silicate
[0096] Looking now at Table 7, when molten iron was poured onto the
cores, the sodium silicate and both collagen+silicate cores did not
exhibit measurable erosion as shown by the zero readings in the
table. In contrast, the phenolic urethane (P-U) cores exhibited
slight erosion and the collagen cores exhibited significant
erosion. The phenolic urethane cores lost only 0.02 cm of core
depth and 0.42 to 0.72 grams of sand per kilogram of iron poured.
The collagen core exhibited the greatest erosion, while
experiencing the least molten iron. For example, the collagen core
erosion depth and sand erosion were approximately 20 times greater
and over 10 times greater, respectively, per kilogram of molten
iron when compared with the phenolic urethane core samples.
[0097] The sodium silicate core decreased slightly in hardness
whereas the collagen and collagen+silicate cores exhibited more
significant decreases in hardness when experiencing a similar
amount of molten iron. Also, the hardness of the phenolic urethane
core decreased significantly when experiencing molten iron, to less
than half the sodium silicate core hardness.
TABLE-US-00007 TABLE 7 Sample 0.85% 0.87% P-U.sup.1 P-U 1.28% Na
Sil, Li/K Sil, Parameter Collagen (HC).sup.2 (TEA).sup.3 Na
Sil.sup.4 1% Col.sup.5 1% Col Iron Kg 8.50 16.98 18.81 17.03 17.61
19.01 Poured Hardness Pre- 77.5 73.5 85.5 76.0 78.5 85.0 Pour Post-
33.3 24.7 29.8 64.0 44.2 45.5 Pour Erosion Total 3.08 0.36 0.33 0 0
0 Depth (cm) cm/kg 0.362 0.021 0.018 0 0 0 Iron Sand Total (g)
44.19 12.30 7.92 0 0 0 Erosion g/kg 5.20 0.72 0.42 0 0 0 Iron
.sup.1Phenolic urethane .sup.2Heat cured phenolic urethane
.sup.3TEA cured phenolic urethane .sup.4silicate .sup.5collagen
[0098] In view of the teaching presented herein, it is to be
understood that numerous modifications and variations of the
present invention will be readily apparent to those of skill in the
art. As such, the foregoing is illustrative of specific embodiments
of the invention but is not meant to be a limitation upon the
practice thereof. It is the following claims, including all
equivalents, which define the scope of the invention.
REFERENCES
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