6,086,647 Molasses/oil coal treatment fluid and method

Patent Number/Link:

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

COOLER

.,.L

TREATMENT FLUID

ApPLICATOR

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

w Z

u<{

_ ~ 400 I "-,~ L.."l I

>-0

I--I

~ I- 300 I ~,~ l'..~ I

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.

•

~.....

~=.....

'""'"

~'""'"

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. \

......::I

EFFECT OF SHEAR ON VISCOSITY

(WESTERN SUGAR MOLASSES AND CONOCO COAL TREATING OIL CONTAINING 20% ASPHALT)

~- ,•... - .--.------------+---- - •

~ '"' ,...

ill

(/)

a.. (/)

~o z Z

ill <l

u(/)

~ :::>

>- 0

~ ::I:

(/)1o

(/)

1000

800

600

400

200

~ \

i .\\-..\", I " --- \

\ ,

~~'"n~"""'"

'" - -

. ----~---~

~~~

- 0: 100 MOLASSES:OIL

--8- 60:40 MOLASSES:OIL

BROOKFIELD RV VISCOMETER

#7 SPINDLE (AMBIENT TEMPERATURE)

VISCOMETER SPEED, RPM

--+-- 40:60 MOLASSES:OIL

----e-- 0: 100 MOLASSES:OIL

FIG 2

._--_._~--_._-----

-A- 50:50 MOLASSES:OIL

d•

'JJ.

•

~.....

~=.....

'""'"

~'""'"

CCC

'JJ =~

~....

o....,

...0. '\ =00

...0. '\

0'\

......::I

(/)

a....

rzw

r>-(/)

(/)

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.

•

~.....

~=.....

'""'"

~'""'"

CCC

'JJ. =~

~....

o....,

80 100 120 140 160

1001 I I I I I

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. \

......::I

u.s. Patent Jui. 11,2000 Sheet 4 of 4 6,086,647

RAW COAL SOURCE

ill

DRYER

COOLER

,J/

TREATMENT FLUID

ApPLICATOR

FIG 4

6,086,647

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.

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

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.

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

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.

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. 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.

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