6,086,647
Jui. 11,2000
[11]
[45]
111111111111111111111111111111111111111111111111111111111111111111111111111
US006086647A
Patent Number:
Date of Patent:
United States Patent [19]
Rahm et ai.
[73] Assignee: RAG Coal West, Inc., Gillette, Wyo.
[54] MOLASSES/OIL COAL TREATMENT FLUID
AND METHOD
[75] Inventors: Randall L. Rahm; Kevin B. Avery,
both of Gillette, Wyo.; Mark H.
Berggren, Golden, Colo.
References Cited
ABSTRACT
5/1981 Anderson 44/282
5/1982 Burns . 44/608
6/1983 Pike 44/530
12/1983 Matthews 44/501
2/1985 Paersch et al. 44/564
4/1986 Siddoway et al. 44/577
11/1990 Wen et al. 44/568
5/1994 Bennett 252/88.1
4,265,637
4,331,445
4,389,218
4,421,520
4,501,593
4,582,511
4,969,928
5,310,494
A composition and method for applying to a coal product for
dust suppression, water repellency, and spontaneous combustion
potential reduction. The composition includes
molasses and a hydrocarbon-based solution, such as an
oil-containing solution. The oil-containing solution is substantially
free of water and may comprise about 20%
asphalt. Both the molasses and the oil-containing solution
may comprise at least about 40% of the total composition by
weight. The method of applying the composition includes
reducing a moisture content of a plurality of pieces of coal,
cooling the plurality of pieces of coal after said reducing step
and treating the plurality of pieces of coal after the reducing
step, with a composition comprising an oil and molasses.
18 Claims, 4 Drawing Sheets
[57]
Primary Examiner-Alan Diamond
Attorney, Agent, or Firm-Bruce E. Dahl, Esq.; Dahl &
Osterloth LLP
11/1932 Broeman 44/545
11/1937 Fife .... ... 44/602
11/1940 Groll et al. 44/600
1/1973 Trechock et al. 44/602
10/1976 Johnson et al. 44/501
10/1976 Johnson 44/501
5/1980 Anderson et al. 208/23
U.S. PATENT DOCUMENTS
Appl. No.: 08/235,542
Filed: Apr. 29, 1994
Int. CI? C10L 5/04; ClOL 5/24
U.S. Cl. 44/620; 44/572; 44/602;
252/88.1
Field of Search 44/620, 602, 572;
252/88, 88.1
1,886,633
2,098,232
2,222,945
3,711,318
3,985,516
3,985,517
4,201,657
[21]
[22]
[51]
[52]
[58]
[56]
RAW COAL SOURCE
ill
,,1
DRYER
20
1
COOLER
30
.,.L
TREATMENT FLUID
ApPLICATOR
40
EFFECT OF MOLASSES: OIL RATIO ON VISCOSITY
(BEET MOLASSES AND CONoeo COAL TREATING Oil CONTAINING 20% ASPHALT)
800 i I
700 I l'
w 600 I ['\,
C/)
oa..
I-- en 500 I ~,~ L.."l I
zO
w Z
u<{
_ ~ 400 I "-,~ L.."l I
>-0
I--I
~ I- 300 I ~,~ l'..~ I
u
C/)
> 200 I ~'"'" L.'-" I
100 I h..'-~'-~ l"\..~ I
a ,P<2Q'!t'-'~ I psX.?9 i psX.?9 i IS'3 i t")I)('i."1 I ~'" i t")(")<j i '"V'V'" i~,
d•
'JJ.
•
~
~.....
~=.....
~
~
'""'"
~'""'"
N
CCC
'JJ. =~
~....
o.'"."..'",
~
a 10 25 40 50 60 75
WEIGHT PERCENT MOLASSES IN MIXTURE
90 100
FIG I
BROOKFIELD RV VISCOMETER; 1.0 RPM; AMBIENT TEMPERATURE
#5 SPINDLE FOR HOLLY MOLASSES MIXTURES; #7 SPINDLE FOR WESTERN MOLASSES MIXTURES
~HOllY MOLASSES ~ WESTERN MOLASSES
...0. \ =00
...0. \
0\
~
......::I
o
o
EFFECT OF SHEAR ON VISCOSITY
(WESTERN SUGAR MOLASSES AND CONOCO COAL TREATING OIL CONTAINING 20% ASPHALT)
~- ,•... - .--.------------+---- - •
~ '"' ,...
ill
(/)
o
a.. (/)
~o z Z
ill <l
u(/)
~ :::>
>- 0
~ ::I:
(/)1o
u
(/)
>
1000
800
600
400
200
\,
\
\
~
~ \
i .\\-..\", I " --- \
\ ,
~~'"n~"""'"
'" - -
. ----~---~
~~~
5
- 0: 100 MOLASSES:OIL
--8- 60:40 MOLASSES:OIL
BROOKFIELD RV VISCOMETER
#7 SPINDLE (AMBIENT TEMPERATURE)
10
VISCOMETER SPEED, RPM
--+-- 40:60 MOLASSES:OIL
----e-- 0: 100 MOLASSES:OIL
FIG 2
._--_._~--_._-----
15
-A- 50:50 MOLASSES:OIL
~
't
20
d•
'JJ.
•
~
~.....
~=.....
~
~
'""'"
~'""'"
N
CCC
'JJ =~
~....
N
o....,
~
...0. '\ =00
...0. '\
0'\
~
......::I
UJ
(/)
o
a....
rzw
U
r>-(/)
o
u
(/)
>
EFFECT OF TEMPERATURE ON VISCOSITY
(HOllY SUGAR MOLASSES AND CONoeo COAL TREATING Oil CONTAINING 20% ASPHALT)
1,000,000 I ;
100,000 I =----__: I
10,000 I 'V>- --= --... co::::: >.::::::-- --= --... I
d•
'JJ.
•
~
~.....
~=.....
~
~
'""'"
~'""'"
N
CCC
'JJ. =~
~....
~
o....,
~
80 100 120 140 160
1001 I I I I I
60
I,oooi ~~ ==---=--~ I
___ 0:100 MOLASSES:OIL
-B- 75:25 MOLASSES:OIL
BROOKFIELD RV VISCOMETER
#5 SPINDLE (20 TO 100 RPM)
TEMPERATURE, F
-+-- 25:75 MOLASSES:OIL
~ 0: 100 MOLASSES:OIL
FIG 3
--6-- 50:50 MOLASSES:OIL
...0. \ =00
...0. \
0\
~
......::I
u.s. Patent Jui. 11,2000 Sheet 4 of 4 6,086,647
RAW COAL SOURCE
ill
1-
DRYER
20
1-
COOLER
30
,J/
TREATMENT FLUID
ApPLICATOR
40
FIG 4
6,086,647
2
DETAILED DESCRIPTION
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is based upon the properties and
performance characteristics of molasses and oil compositions
applied to an upgraded coal product for dust
suppression, moisture repellency, and/or spontaneous combustion
potential reduction. It has been discovered that,
when mixed in the proper ratios, molasses and oil compo-
60 sitions exhibit particularly desirable ambient viscosity, shear
viscosity and high temperature viscosity characteristics
which provide enhanced dust suppression and moisture
repellency over the use of either molasses or oil alone, and
which provide enhanced application capabilities.
Typical properties of the individual components utilized
for developing the composition of the present invention are
summarized in Table 1 below.
65
FIG. 1 is a chart illustrating the change in composition
viscosity with changing weight percent molasses.
FIG. 2 is a graph illustrating the effect of shear on the
viscosity of various compositions.
FIG. 3 is a graph illustrating the effect of temperature on
the viscosity of various compositions.
FIG. 4 is a block diagram of a general coal drying process
50 in accordance with principles of the present invention.
ses and the hydrocarbon portion of the hydrocarbon-based
solution each make up between about 40% and about 60%
of the composition by weight. In another embodiment, the
hydrocarbon-based solution comprises an oil-containing
5 solution which is substantially free of water. The oilcontaining
solution may comprise asphalt (e.g., up to about
50% of the solution by weight) to increase the viscosity of
the composition. The oil-containing solution may advantageously
be substantially free of volatile fractions so that
10 hydrocarbon gases are not emitted during handling,
transportation, or utilization. In order to inhibit run-off, the
composition of the present invention preferably has a viscosity
of at least about 50,000 cp at 70° F. In order to
improve sprayability at elevated temperatures, the compo-
15 sition of the present invention preferably has a viscosity of
less than about 3,000 cp at 150° F. The composition of the
present invention may also exhibit significant shear thinning
to facilitate application thereof to the coal product by
high-shear application methods, such as spraying.
A method for applying the above-described composition
is also disclosed. The method generally comprises the steps
of reducing the moisture content of a plurality of pieces of
coal by heating the same, cooling the plurality of pieces of
coal, and treating the plurality of pieces of coal after the
25 reducing step with a composition comprising molasses and
an oil-containing solution. The reducing step occurs before
the cooling step and preferably reduces the moisture content
of the coal to less than about 10% by weight. The cooling
step preferably reduces the temperature of the coal to less
30 than about 125° F. The treating step may be performed
before or after the cooling step, but nonetheless is performed
after the reducing step. When treating the coal, the composition
may be heated to at least about 120° F. to reduce the
viscosity thereof and facilitate application of the composi-
35 tion to the coal (e.g., by spraying). The treating step advantageously
may form a coating of the composition on the coal
and maintains a substantially uniform concentration of the
molasses and oil throughout the coating.
SUMMARY OF THE INVENTION
BACKGROUND OF THE INVENTION
1
MOLASSES/OIL COAL TREATMENT FLUID
AND METHOD
FIELD OF THE INVENTION
The present invention achieves the above-stated requirements
by providing a novel method and composition for
treating coal products.
The composition generally comprises molasses and a
hydrocarbon-based solution. In one embodiment, the molas-
In the processing of raw coal, it is generally considered
beneficial to reduce the moisture content of low-rank coals
(e.g., lignite and subbituminous coals) prior to shipment to
the customer. Such reduced moisture content upgrades the 20
low-rank coal to enhance the coal product heating value and
decreases the weight of the coal to decrease transportation
costs.
Removal of surface moisture and interstitial moisture
from low-rank coals has the undesirable effect of increasing
particle friability and dustiness during handling. Some dustiness
also occurs due to loss of surface moisture by natural
means during mining, preparation and storage. The presence
of dust is undesirable in that it impairs visibility, is harmful
if inhaled for long periods of time, and can result in loss of
coal product. More significantly, dustiness can also result in
spontaneous combustion during shipment and/or storage of
the coal product.
Dust suppressants have been developed for reducing the
dustiness of coals and thereby reducing the incidence of
spontaneous combustion. Some dust suppressants are also
designed to provide a relatively moisture repellant coating
on the coal product, thereby inhibiting moisture reabsorption
into the dry coal product which would reduce the product 40
heating value. For example, petroleum-based fluids have
been applied to coal particles (i.e., sprayed or immersed) to
reduce the dustiness of and provide a moisture repellant
coating to the coal product. However, petroleum-based
fluids can be expensive, typically have high sulfur content, 45
and can have low viscosities resulting in run-off. Molasses
has also been utilized as a dust suppressant. Molasses is
readily available and is low in cost, but lacks sufficient
moisture repellency to be considered alone as a high-grade
coal dust suppressant.
Based upon the foregoing, there is a need for an improved
dust suppressant which can be economically applied to coal
products to inhibit dust formation and improve moisture
repellency of the coal product. The composition should have
a high static viscosity at ambient temperature to inhibit 55
run-off of the composition during long-term storage of the
coal product. Further, the viscosity of the composition
should substantially decrease with increasing temperature
and increasing shear rate to facilitate application of the
composition to the coal product.
The present invention generally relates to the processing
of carbonaceous materials. More particularly, the present
invention relates to a composition which can be applied to
the surface of a carbonaceous material, such as coal, to
suppress the formation of dust, improve moisture repellency,
and/or reduce air flow therethrough to reduce the potential
for spontaneous combustion of the coal product during the
processing and/or storage thereof The present invention also
relates to a method for applying the composition to the
carbonaceous material.
6,086,647
3 4
The same shear-thinning behavior leads to relatively high
viscosity at low shear (i.e., when the treatment composition
is at rest on the surface of the coal). As a result, the treatment
remains near the particle surfaces after application and is
5 available to capture additional dust which may be generated
during subsequent handling. In addition, the high viscosity
at low shear inhibits loss of treatment composition due to
run-off during storage. However, as can be seen in FIG. 2
and as noted above, the viscosity of the composition of the
present invention is significantly reduced by the shear forces
10 imparted thereon during spraying. In one embodiment, the
viscosity of the composition is reduced by at least 25
percent, and preferably by more than about 75 percent,
during spraying by the noted shear-thinning effect which
facilitates the application of compositions of the present
15 invention onto the coal product.
The viscosities of molasses, oil, and blends of molasses
and oil all decrease with increasing temperature as illustrated
in FIG. 3. However, the rate of viscosity decrease with
an increase in temperature is greater for compositions in
accordance with principles of the present invention. This
20 desirable feature allows the treatment composition of the
present invention to be heated and thereby thinned during
spraying for improved atomization and product coverage.
FIG. 3 specifically illustrates an example of viscosity
decrease as a function of increasing temperature exhibited
25 by blends of Holly beet molasses and Conoco oil containing
20 percent asphalt. Viscosity decreased by roughly two
orders of magnitude when temperature increased from 70° F.
to 150° F. for all molasses:oil blend ratios tested For
example, the 50:50 ratio sample decreased in viscosity from
30 about 300,000 cp at 70° F. to about 2,000 cp at 150° F. The
optimum spraying temperature can be resolved for any
particular treatment application by experimentation.
However, in one embodiment, the temperature of the composition
when sprayed ranges from about 150° F. to about
1700° F.
Thickeners and additives may be added to increase viscosity
of the composition. For example, in the examples
noted above, Conoco 85100 asphalt was added to the
Conoco oil at a concentration of about 20 percent prior to
blending with molasses. The oil exhibited a viscosity
40 increase of about a factor of three as a result of the asphalt
addition. Both the Conoco oil and the Conoco oil with
asphalt exhibit nearly Newtonian rheological behavior (no
shear thinning).
Similarly, sugar may be added to the oil to increase
45 viscosity. In one example, sugar was added to Conoco oils
with and without asphalt at a concentration of about 30
percent by weight. In each case, viscosity increased by a
factor of about two. Nearly Newtonian rheological behavior
was observed in each case after sugar addition. Other
50 additives including, but not limited to, waxes and polymers
may be included to tailor viscosity and tackiness to a
particular application.
Surprisingly, the blending of molasses and oil results in a
stable mixture which exhibits the desirable property of little
55 or no separation during storage and handling. That is, the
mixture is substantially homogeneous and remains so even
when on the coal product. Molasses blended with oil across
all ratios tested in the examples noted above exhibited no
apparent separation. By contrast, a mixture of sugar and
water (1:1 ratio by weight) was prepared and then blended
60 with Conoco oil at a ratio of one part sugar water to one part
oil. The resulting mixture exhibited rapid separation of the
water and oil components. Additives including, but not
limited to, surfactants and emulsifiers may be added to
optimize mixture characteristics for particular types of syr-
65 ups and oils. However, in the case of the oil and molasses
composition, no emulsifiers are needed for mixing the oil
and molasses into a substantially homogenous mixture.
o
3-5
5,000-25,000
8-9
Coal Treating Oil
20-30
0.3-0.8
2,000-30,000
10-12
Beet Molasses
TABLE 1
Typical Properties of Molasses and Coal Treating Oil
Moisture, %
Sulfur, %
Viscosity at 70° E, cp
Density, lb/gal
In the described embodiment, the molasses component
comprises beet molasses supplied by either the Holly Sugar
Corporation or the Western Sugar Company. The molasses
generally comprises about 50 percent sugar, about 25 percent
moisture, and about 25 percent proteins and dissolved
salts. It should be appreciated that the molasses component
of the present invention is not limited to beet molasses, and
may instead include cane molasses or other syrups or sugars.
However, as will be discussed below, the use of sugar alone
in combination with oil has problems with separation.
The oil component of the present invention is a
hydrocarbon-based solution. Preferably, the oil exhibits little
or no volatility at ambient temperature so that hydrocarbon
gases are not emitted during handling, transportation or
utilization. In the described embodiment, the oil comprises
a petroleum-derived coal treating oil supplied by Conoco,
Inc. (Product Code 1060). The Conoco oil comprises an
aromatic hydrocarbon oil, such as decant oil, mixed with
about 20 percent asphalt material, such as a 100 penetration
asphalt obtained during conventional petroleum refining.
The Conoco oil is described in more detail in u.S. Pat. No.
4,201,657 to Anderson et aI., which is incorporated herein
by reference. Other oils may be used, including coalderived,
plant-derived, and animal-derived oils.
It has been discovered that blends of beet molasses and oil
produce a thick liquid which is of greater viscosity than 35
either component individually. FIG. 1 illustrates the effect of
the molasses:oil ratio on composition viscosity. Compositions
containing between 40 percent and 60 percent molasses
and oil exhibit significantly greater viscosities than the
individual components alone. More specifically, such compositions
have viscosities well in excess of 100,000 cp at 70°
F., while the individual components have maximum viscosities
on the order of about 30,000 cp at 700° F. Equal parts
of the two components result in substantially greater viscosity
than other mixtures tested (i.e., on the order of about
700,000 cp at 70° F. for a 50:50 mixture of Western molasses
and Conoco coal treating oil containing 20 percent asphalt).
Without being limited to a particular theory, it is believed
that the unexpected extreme increase in viscosity may be
due in part to hydrogen-bonding interactions between the oil
and molasses. It is this increased viscosity of the molasses
and oil compositions which constitutes one of the desirable
aspects of the present invention.
The Conoco oil and Holly and Western molasses components
each individually exhibit nearly Newtonian rheological
behavior. This characteristic is reflected in the observation
that viscosity remains nearly constant as a function of
shear rate, as illustrated in FIG. 2. Blends of molasses and
oil containing greater than about 40 percent and less than
about 60 percent molasses, however, exhibit significant
shear thinning, or pseudoplastic rheological behavior. This
desirable characteristic leads to relatively low viscosity (i.e.,
compared to the viscosity at low shear) under the high shear
conditions which are encountered in spray nozzles. As a
result, good atomization and coverage of the treatment
composition onto coal is possible. The characteristic of
decreasing viscosity as a function of increasing rotational
speed of the viscometer spindle, as illustrated in FIG. 2, is
indicative of shear thinning.
6,086,647
5 6
100.0
83.7
97.6
99.2
After Tumblingb
98.4
95.2
97.1
98.6
As Produced
Opacity Test Result, % Light
Transmittance, 15 Seconds After
Dropping Samplea
9.9
9.9
10.0
9.5
Product
TABLE 3
Effect of Treatment on Dry Subbituminous Coal Dustiness
(6 Gallons Per Ton Application Rate for Each Treatment)
Treatment Type
'100% ~ No dust.
bUsing ASTM 0-441 tumbler apparatus.
Conoco Coal Treating Oil
Beet Molasses
10:1 Molasses:Water
1:1 Oil:Molasses
Table 4 below summarizes results obtained from coal and
upgraded products following treatment with oil, molasses,
and a blend of oil and molasses on an industrial scale.
Results are shown for products as-produced and after stockpiling.
The coals shown in Table 4 were stockpiled for a few
weeks prior to sampling. The tests were conducted during
different industrial scale test operations. In general, stockpiling
of coal or products results in degradation due to
moisture changes and oxidation. Temperatures monitored in
the stockpiles showed that all products exhibited some self
heating. Previous experience has shown that many untreated
45 upgraded products cannot be stockpiled without sealing
surfaces to block airflow. Untreated products will often
produce heat from oxidation and will eventually exhibit
spontaneous combustion in locations where heat is generated
at a rate greater than it is dissipated. Treated products
50 in these examples exhibit heating but at a much lower rate
due to physical and chemical effects of product pore blockage
by the treatments.
described above. A similar upgraded coal produced was
treated with Conoco coal treating oil using an application
rate of six gallons per ton with the result that dustiness was
nearly eliminated.
Table 3 compares laboratory dustiness data using various
potential alternative dust suppressants. Industrially produced
upgraded coal was treated in the laboratory at a rate
of six gallons treatment composition per ton of product.
These test results show that beet molasses alone did not
10 perform as well as Conoco oil alone for suppression of dust
at a comparable application rate. Slight dilution of the
molasses resulted in a significant improvement of results;
however, performance was still noticeably poorer than oil
alone. A freshly prepared product treated with a 1:1 oil:mo-
15 lasses mixture provided dustiness results which nearly
matched those of the oil alone.
After Tumblingb
Opacity Test Result, % Light
Transmittance, 15 Seconds After
Dropping Samplea
As Produced
TABLE 2
Product
Effect of Drying and Treatment on Subbituminous Coal Dustiness
As may be evident from the above description of the
composition, the preferred method of application of the
composition to the coal product is spraying. For example,
the composition may be heated to between about 500 F. and
2500 F. to decrease the viscosity of the composition and 5
sprayed through a known spray nozzle. As noted, in one
embodiment, the composition is heated to a temperature of
about 1500 F. to about 1700 F. before spraying. However, it
should be appreciated that other methods of application may
be utilized. For example, the coal product may be immersed
in a bath of the composition and subsequently removed
therefrom to provide composition coverage over the surface
of the coal product. Moreover the composition may be
applied in a blender such as the PK Zig-Zag® Continuous
Blender by Patterson-Kelley Co. of East Stroudsbury, Pa.
Furthermore, the coal product may be treated in coal transfer
chutes or at the discharge of conveyors.
The effectiveness of a particular dust suppressant can be
measured utilizing an opacity meter. The opacity meter is
based on the principle of light transmittance through a cloud
of dust created when approximately 200 grams of sample are 20
dropped into a vertical cylinder chamber of approximately 4
inches in diameter and 32 inches in length. A laser provides
a beam of light which is passed through the dust cloud to a
photo detector. Light transmittance at a period of time after
dropping a test sample into the chamber is used as a relative 25
indicator of sample dustiness. Samples may be tested
as-produced and also after tumbling in an apparatus and
procedure as described in ASTM D-441, Friability Test for
Coal. Experience has shown that the tumbling procedure
provides conditions which a raw coal or upgraded coal 30
product must endure in the laboratory without significant
dust production in order to be handled and transported
industrially.
Table 2 below shows results of laboratory tests performed
35 to illustrate the relative dustiness of raw coal ("as is" from
the mine), upgraded (dried) coal product, and upgraded
(dried) coal product treated with a commercial petroleumbased
spray agent. The raw coal and products shown in
Table 2 were produced at a nominal minus %-inch particle
size containing significant fractions of fine material (less 40
than Y4 inch). The table provides the moisture content of
each freshly prepared coal or coal product and the dustiness
based on opacity reader meetings taken as described above.
Raw Coal
Dry, Untreated Coal
Dry, Oiled Coate
30.8
9.4
9.9
100.0
82.9
98.4
100.0
26.7
100.0 55
TABLE 4
Effect of Treatment Type and Stockpiling on Dry Coal Dustiness
'100% ~ No dust.
bUsing ASTM 0-441 tumbler apparatus.
"Treated with 6 gallons Conoco coal treating oil per ton of product.
As can be seen in Table 2, the raw coal sample exhibited 60
no dustiness. This is a result of the saturation of internal coal
pores with moisture and the presence of surface moisture,
which acts to adhere coal fines. During industrial-scale
drying of a similar raw coal, total moisture was reduced
from approximately 30 percent to less than 10 percent. The 65
untreated, upgraded coal product exhibited significant
dustiness, particularly following the tumbling procedure
Coal
and Treatment
Type
Raw Coal,
Untreated
Dry, Oil
Treated
As Produced After Stockpiling
Opacity Test Opacity Test
Result, % Light Result, % Light
Transmittance, Transmittance, 15
Product 15 Seconds After Product Seconds After
% H20 Droppingb % H20 Droppingb
29.5 99.9 23.8 21.6
9.9 100.0 12.1 90.3
6,086,647
7 8
coal may be directed to a treatment fluid applicator 40 which
applies a composition in accordance with principles of the
present thereto to the coal. However, as noted above this
composition may be applied in a variety of manners.
5 Moreover, it should be noted that although the composition
is illustrated as being applied after exiting the cooler 30,
broadly the present invention includes applying the composition
at any time after "drying" the coal to the desired
degree. A more detailed discussion of a coal drying process
is disclosed in u.s. Pat. No. 4,354,825 to Fisher et aI., the
entire disclosure of which is incorporated by reference
herein.
The foregoing description of the present invention has
been presented for purposes of illustration and description.
Furthermore, the description is not intended to limit the
invention to the form disclosed herein. Consequently, variations
and modifications commensurate with the above
teachings, and the skill or knowledge of the relevant art, are
within the scope of the present invention. The embodiments
20 described hereinabove are further intended to explain best
modes known for practicing the invention and to enable
others skilled in the art to utilize the invention in such, or
other, embodiments and with various modifications required
by the particular applications or uses of the present inven-
25 tion. It is intended that the appended claims be construed to
include alternative embodiments to the extent permitted by
the prior art.
What is claimed is:
1. A method for producing a coal product from raw coal,
30 comprising the steps of:
heating the raw coal in a coal dryer;
reducing a moisture content of the raw coal using said
heating step to produce dried coal;
cooling the dried coal after said reducing step; and
treating the dried coal after said reducing step and all
heating steps involved in producing the coal product
from the raw coal with a liquid comprising oil and
molasses to produce the coal product, wherein said oil
and molasses are mixed together before said treating
step to provide said liquid used by said treating step.
2. A method for producing a coal product as set forth in
claim 1, wherein said reducing step comprises reducing the
moisture content of the raw coal to less than about 10% by
45 weight.
3. A method for producing a coal product as set forth in
claim 1, wherein said cooling step comprises cooling the
dried coal to less than about 125° F.
4. A method for producing a coal product as set forth in
50 claim 1, further comprising the step of:
heating the liquid to a temperature between about 50° F.
and about 250° F. before said treating step.
5. A method for producing a coal product as set forth in
claim 4, wherein said step of heating the liquid increases the
55 temperature of the liquid to a temperature between about
150° F. and about 170° F.
6. A method for producing a coal product as set forth in
claim 1, wherein said treating step comprises forming a
coating on the dried coal and maintaining a substantially
60 uniform concentration of the oil and molasses throughout
the coating.
7. A method for producing a coal product as set forth in
claim 1, wherein said treating step comprises spraying the
liquid into the dried coal.
8. A method for producing a coal product as set forth in
claim 1, wherein said treating step comprises immersing the
dried coal into the liquid.
As Produced After Stockpiling
TABLE 4-continued
Effect of Treatment Type and Stockpiling on Dry Coal Dustiness
'All treated coals received an application of about 6 gallons per ton.
b100% ~ No dust.
The results in Table 4 show that the raw coal became very
dusty after stockpiling due to loss of moisture. Removal of
surface moisture liberated fines which had been adhering to
the particle surfaces. The oil-treated upgraded product also
exhibited an increase in dustiness (i.e., light transmittance
decreased from 100.0 to 90.3 percent) during stockpiling
while exhibiting an increase in moisture content from 9.9 to
12.1 percent. It is thought that oxidation of the product rather
than moisture changes are responsible for the increased
dustiness of this product.
A similar product treated with molasses was not sampled
as-produced for dustiness testing but was initially produced
at about 10 to 11 percent moisture and contained very little
dust based on visual observation. After stockpiling, a significant
dustiness was measured (i.e., light transmittance
value of 63.2 percent) even though moisture content
increased somewhat.
35
A similar upgraded product, which was treated with a
blend of molasses and oil, exhibited the smallest increase in
dustiness of all coals or products tested following stockpiling.
Even though this product lost moisture during stockpiling
(i.e., decreased from 10.8 to 5.3 percent), dustiness 40
showed only a slight drop from the as-produced value.
A treatment application rate of 6 gallons per ton was
selected for the series of tests described above. Depending
on the particular nature of the coal or product, the application
rate can be adjusted to provide the desired degree of
dust control. An additional consideration in the overall
application rate is the oil addition requirement to impart
moisture repellency to the product. For example, moisture
repellency can be induced in molasses and oil mixtures at an
oil concentration lower than that required to induce favorable
shear-thinning flow properties. In some applications,
treatments containing low concentrations of oil will perform
satisfactorily and may constitute an optimum formulation.
The general methodology of producing a coal product in
accordance with principles of the present invention is schematically
illustrated in FIG. 4. Generally, a stream of raw
coal (e.g., having a moisture content of about 30% by
weight) is provided from a source 10 (e.g., a crusher or
grinder) to a dryer 20 (e.g., a fluidized bed reactor). In the
dryer 20, the moisture content of the raw coal therein is
reduced to the desired degree (e.g., by passing a heated gas
through the bed of coal). Thereafter, coal is removed from
the dryer 20 and directed to a cooler 30 (e.g., another
fluidized bed reactor) where the temperature of the "dried"
coal is reduced to the desire degree (e.g., 125° F. and by, for 65
instance, passing ambient temperature air through the coal in
the cooler 30). After the desired temperature is achieved, the
6,086,647
9
9. A method for producing a coal product as set forth in
claim 1, wherein the liquid has a viscosity before said
treating step, and wherein said treating step comprises
spraying the liquid, shearing the liquid during said spraying
step, and reducing the viscosity of the liquid by more than
about 25 percent during said shearing step.
10. A liquid for treating a coal product, comprising:
a mixture of molasses and a hydrocarbon-based solution,
wherein:
said molasses is present in the amount of at least about
40% of said liquid by weight; and
said hydrocarbon-based solution comprises a hydrocarbon
portion wherein said hydrocarbon portion comprises
at least about 40% of said liquid by weight,
and wherein said molasses and said hydrocarbonbased
solution are mixed before being used in the
treatment of the coal product.
11. A liquid for treating a coal product as set forth in 10,
wherein said hydrocarbon-based solution is substantially
free of water.
12. A liquid for treating a coal product as set forth in 10,
wherein said hydrocarbon-based solution comprises asphalt.
10
13. A liquid for treating a coal product as set forth in claim
12, wherein said asphalt makes up about 20% of said
hydrocarbon-based solution by weight.
14. A liquid for treating a coal product as set forth in 10,
5 wherein said hydrocarbon-based solution is substantially
free of volatile fractions.
15. A liquid for treating a coal product as set forth in 10,
wherein said liquid has a viscosity of at least about 50,000
10 centipoise at 70° F.
16. A liquid for treating a coal product as set forth in claim
15, wherein said liquid has a viscosity of less than about
3,000 centipoise at 150° F.
17. A liquid for treating a coal product as set forth in claim
15 10, wherein said liquid has a viscosity of at least 300,000
centipoise at about 700° F.
18. A liquid for treating a coal product as set forth in claim
10, wherein said molasses and said hydrocarbon-based solution
each comprise about 50% of said liquid on a weight
20 percentage basis.
* * * * *
UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION
PATENT NO : 6,086,647
DATED : July 11,2000
INVENTOR(S): Randall L. Rahm; Kevin B. Avery, Mark H. Berggren
It is certified that error appears in the above-identified patent and that said Letters Patent
are hereby corrected as shown below:
IN THE CLAIMS:
In Column 10, line 16, change "700 F." to --70 F.--
Signed and Sealed this
Twenty-second Day of l\1ay, 2001
Attest:
Attesting Officer
NICHOLAS P. GOmCI
Acting Director (~r the United Stares Patent and Trademark Office