CA1305608C - Composition and process for agglomerating coal particles - Google Patents
Composition and process for agglomerating coal particlesInfo
- Publication number
- CA1305608C CA1305608C CA 508993 CA508993A CA1305608C CA 1305608 C CA1305608 C CA 1305608C CA 508993 CA508993 CA 508993 CA 508993 A CA508993 A CA 508993A CA 1305608 C CA1305608 C CA 1305608C
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- Prior art keywords
- coal
- binder
- fiber
- weight
- composition
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
- C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
- C10L5/10—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE INVENTION
An improved coal composition and process for agglomerating coal particles is disclosed. Between three and twelve percent by weight of a hydrophobic binder and between one and five percent by weight of a fiber is mixed with fine coal particles. The coal particles, binder, and fiber are then formed into an agglomerate which resists breakage and moisture sorption. In another embodiment of the invention, coal particles exceeding 590 microns in diameter can be mixed with the coal, binder, and fiber before the agglomerate is formed.
An improved coal composition and process for agglomerating coal particles is disclosed. Between three and twelve percent by weight of a hydrophobic binder and between one and five percent by weight of a fiber is mixed with fine coal particles. The coal particles, binder, and fiber are then formed into an agglomerate which resists breakage and moisture sorption. In another embodiment of the invention, coal particles exceeding 590 microns in diameter can be mixed with the coal, binder, and fiber before the agglomerate is formed.
Description
~3~
IMPROVED COMPOSITION AND PROCESS
FOR AGGLOMERATING COAL PARTICLES
Field of the Invention The present invention relates to an improved composition and process for agglomerating coal particles. More particularly, the present invention relates to a process of selectively adding fiber and hydrophobic binder to coal particles to increase the strength and Moisture repellency of agglomerates formed from the coal particles.
Background of the Invention In the mining and processing of coal, small particles of coal known as "coal fines" are randomly produced as the coal is handled. Coal fines are usually defined as coal particles having a diameter less than 590 microns. In addition to randomly produced coal fines, coal is often beneficiated to a small particle size`to permit the separation of minerals and inorganic sulphur from the coal.
Coal fines are difficult to handle and to transport because of lack of cohesion among the coal particles. Because coal is ireq~ently transported by open conveyors or by rail ~ , , , ~ I
~3~3~
cars, coal fines are difficult to transport without loss of coal due to "dusting efEects." The coal loss increases as the partlcle size of the coal decreases. To lessen the amount of coal lost during transportation, the particle size of the coal may be increased by various manufacturlng processes such as briquetting, extruding, or by pressurizlng the coal into pellets or pucks. Preferably, the agglomerated coal particles formed by such processes should be sufficiently strong to resist breaking into fine coal as the particles are handled. In addition, the agglomerated coal particles should resist moisture sorption9 due to rain or high humidity, which would decrease the combust~bility of the coal.
Various techniques have been developed for increasing the size and strength of coal particles. In U. S. Patent Number 181,003 to Reinold (1913), a large quantity of moisture and dry paper pulp was added to fine coal before the coal was pressed into brlquets. In U. S. Patent Number 2,066,457 to Decker (1935), water was added to waste paper to form a pulp.
Subsequently, 67 parts of pulverized coal were added to 21 parts of the pulp, excess water was removed from the mixture, and 12 parts of asphalt wëre added as a binder before the mixture was compressed into a briquet. Because these processes add a large amount of papër and other organic matter to the coal, the amount of moisture absorbed by the coal significantly increases. The ,' .~ ,, ,~ ' I
. I
~3~
additional moisture reduces the combustlbility of the coal and increases the amount of residual ash created during the combustion of the coal.
Other techniques have been developed to agglomerate coal particles without increasing the moisture sorption of the particles into an agglomerated particle. For e~ample, asphalt pitch, residual oil; coal tar, and starch have been used to bind coal particles. In U. S. Patent Number 4,126,426 to Verschuur (1978), a slurry of coal particles was divided~into a first fraction of small particles and a second fractlon of large particles. 10 parts of a liquid hydrocarbon binder was added to 90 parts of the first fraction, and the first fraction was recombined with the second fraction. The resulting agglomerate formed by this process reduces the amo~mt of moisture absorbed by the coal after the excess water has been removed. However, the resulting agglomerate is susceptible to breakage and to abrasive wear which degrades the shape of the agglomerate during transportation of the coal.
' ~0 Currently available processes for agglomerating coal ¦
particles are not commercially practical due to several factors. Processes which use large amounts of organic fiber to agglomerate coal particles are subject to moisture sorption, and processes which combine a hydrocarbon binder with coal particles are subject to breakage. Other processes which combine large quantities of organic fiber with large quanti-i&s of a ,.
3L3~
hydro~arbon binder are expensive to use and may not adequately reduce moisture sorption to desirable levels. Therefore, a need exists for an improved composition and process which agglomerates fine coal particles while ma~imi2ing the strength and moisture repellency of the agglomerated particles.
SUMMARY OF THE IN~ENTION
The present invention furnishes an improved composition lU and process for agglomerating fine coal particles which improves the strength of the agglomerated particles while preventing the sorption of an undesirable amount of moisture. The composition comprises between one and five percent fiber by weight of coal combined with between three and twelve percent hydrophobic binder by weight of coal. In a preferred embodiment of the invention, the fiber is organic.
The improved process is practiced by dispersing on the coal a hydrophic binder of between three and twelve percent by weight - 20 o~ coal. Subsequently, between one and five percent of fiber by weight of coal is mixed with the coal and binder, and the coal, .. . .
binder, and fiber are formed into an agglomerate. In an alternative embodiment of the invention, moisture is removed ~
from the coal particles until the moisture con;tent i5 less than .
tweLve percent. In another embodiment of the invention, the coal, binder, and fiber are nli~ed with additional coal particles having a diameter greater than 590 microns before the agglomerate is formed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As set forth above, known processes do not permit the economic manufacture of a coal agglomerate which has acceptable mechanical strength and moisture repellency. The present .
invention accomplishes these objectives by adding between three and twelve percent by weight of a hydrophobic binder and between one and five percent by weight of organic fiber to the coal.
To practice the invention, the moisture content of fine coal is modified to a selected amount which is preferably between t~o and twelve percent by wei~ht. Moisture can be added by spraying water onto the coal or can be removed by f~Ltration or thermal drying techniques well-known in the art.
29 Subsequently, a hydrophobic binder such as fatty acid residues, sulphite lignin, asphalt, pitch, tar or other hydrocarbon is added to the coal. Preferably, the hydrophobic binder is between two and twelve percent by weight of the coal In one embodiment of the invention, the binder can be:added to the coal before the moisture is removed from or added to the coal. The binder should be adequately mixed with the coal to obtain uniform distribution of the binder. The mixing can be .~ , . . . .
I
I
6~)~
accomplished by techniques well-known in the art which include auger mixing or ribbon blending. If the binder is a petroleum distillation residue such as pitch~ the binder can be heated and sprayed onto the coal with an atomizing nozzle.
Following the addition of the binder to the coal, a fiber having a weight between one and five percent of the coal is mixed with the coal and binder. The fiber can be one of many materials and may be organic or inorganic in nature. Examples of organic fiber include shredded paper, pulverized bark, or wood was~e produced from a sawmill or lumber dressing plant.
Scrap newsprint is useful because it contains a lov amount of mineral flller. In addition, scrap cra~t or sulphite paper may also be used if the combustion of such paper does not result in an unacceptable amount of ash. The waste fiber can be milled by a blade mill or by beaters to separate individual fibers and fiber bundles. During the milling process, the comminuted fibers may be separated by well-known pneumatic classification techniques. Waste fiber having an excessively high mois-ture 20 content may ~e partially dried before the fiber is milled. ~ ;
:, , . . .
Following the addition of the fiber to the coal and binder, the mixture is formed into an agglomerate by techniques well-known in the art. For example, the mixture may be Eormed or compressed into briquets, pellets, or may be extruded into other shapes. Preferablys the agglomerate forming pressure should exceed 8000 psi. In a puck-forming process disclosed in ~35~5~
U. S. Patent Number 4,420,404 to Dravo, a flotation concentrate slurry is thickened and then is loaded into an enclosed compression chamber. A compressive force expresses fluid from the chamber until a coarse puck is formed.
The following three examples are presented to illustrate tests which demonstrate the advantages of the current invention.
Exc~mple 1 In this test, fine coal flotation concentrate (85%
passing a 200 mesh screen) was filtered,.air dried to 4%
moisture, and mechanically mixed with a commercial asphalt emulsion (65% asphalt, 35% water) irl an amount equal to 670 asphalt by weight. To this mixture was added 5% by weight of commercial shredded newsprint, and the whole mixture was dispersed with an auger mixer. Portions of the mixture were then formed at 10,000 psi pressure in a 1/2" diameter cylindrical die. Similar mixtures were prepared without fiber and according to the methods disclosed by the U~ S.
Patents issued to Decker and Reinold tsee above). The results of the tests may be summarized as follows:
., .
.. ..
~L31~
--8~
COMPOSITION PRODUCT MOISTURE COMPRESSIVE
_ SORPTION, WT.%STRENGTH (lb) 1. 6% asphalt, 5% fiber 2.1 174 2. 6% asphalt 14.6 68 3. Method of Decker 41.7 462 4. Method of Reinold 28.9 207 (5% fiber) As demonstrated by these results, Composition I shows an improvement oE L50% over Composition 2 in strength due to the added fiber and also shows a large reduction in moisture sorption (14.6% sorption for asphalt binder ODly, VS. 2.1 sorption for the ~lethod of the present invention). ~he extremely low water sorption in this test is considered due to action of the dry fiber in "blotting" residual moisture from coal surfaces, thereby allowing very effective wetting of the naturally hydrophobic coal surface by the asphalt binder. :
Composition 3 showed very high initial strength (462 lb load to failure vs. 174 lb for Composition 1~, but water sorption is considered to be unacceptably high at 41%.
Composition 3 also contains large amounts of additive materials (20% fiber, 12% asphalt) which are expensive when compared to the market value of the final coal product.
Composition 4 showed a compressive strength which was 18% greater than that of Composition 1. ~owever, the water sorption of Composition 4 was significantly greater than for ' ~L3~
_9_ Composition 1. Therefore, Composition 1 demonstrated the most favorable combination of co~pressive strength and resistance to moisture sorption.
Example 2 Agglomerates were prepared from a coal slurry pursuant 10 to the method disclosed by Dravo (see above). Samples were prepared with no additive, with asphaltic pitch binder as an additive, and with three different amounts of fiber combined with pitch binder. Test results were as follows:
:
, ....
SAMPI.E ~ FORMING AS FORMED MOISTURE DROP FILTRATE
PARTICLE SIZE ADDITIVES -PRESSURE MOISTURE RESORPTION TEST LOSS
(kpsi) (%) (%) (%<1/4") (%:-of :
~ coal) (Scavenger Concentrate 100 mesh x 0, 20 60% - 325 mesh~ 1. none 16 14.2 9.4 10.1 20.1 2. Pitch, S~ 16 10.1 6.1 7.8 22.0 3. P,itch, 5% 14 11.3 6.8 8.1 ~21.4 4. Pitch, 5% 14 13.3 6.~ 7.4 1.2 Fiber, 1%
- -- - f 5. Pitch, 5% 14 13.3 7.3 4.2 2.1 Fiber, 2%
~
IMPROVED COMPOSITION AND PROCESS
FOR AGGLOMERATING COAL PARTICLES
Field of the Invention The present invention relates to an improved composition and process for agglomerating coal particles. More particularly, the present invention relates to a process of selectively adding fiber and hydrophobic binder to coal particles to increase the strength and Moisture repellency of agglomerates formed from the coal particles.
Background of the Invention In the mining and processing of coal, small particles of coal known as "coal fines" are randomly produced as the coal is handled. Coal fines are usually defined as coal particles having a diameter less than 590 microns. In addition to randomly produced coal fines, coal is often beneficiated to a small particle size`to permit the separation of minerals and inorganic sulphur from the coal.
Coal fines are difficult to handle and to transport because of lack of cohesion among the coal particles. Because coal is ireq~ently transported by open conveyors or by rail ~ , , , ~ I
~3~3~
cars, coal fines are difficult to transport without loss of coal due to "dusting efEects." The coal loss increases as the partlcle size of the coal decreases. To lessen the amount of coal lost during transportation, the particle size of the coal may be increased by various manufacturlng processes such as briquetting, extruding, or by pressurizlng the coal into pellets or pucks. Preferably, the agglomerated coal particles formed by such processes should be sufficiently strong to resist breaking into fine coal as the particles are handled. In addition, the agglomerated coal particles should resist moisture sorption9 due to rain or high humidity, which would decrease the combust~bility of the coal.
Various techniques have been developed for increasing the size and strength of coal particles. In U. S. Patent Number 181,003 to Reinold (1913), a large quantity of moisture and dry paper pulp was added to fine coal before the coal was pressed into brlquets. In U. S. Patent Number 2,066,457 to Decker (1935), water was added to waste paper to form a pulp.
Subsequently, 67 parts of pulverized coal were added to 21 parts of the pulp, excess water was removed from the mixture, and 12 parts of asphalt wëre added as a binder before the mixture was compressed into a briquet. Because these processes add a large amount of papër and other organic matter to the coal, the amount of moisture absorbed by the coal significantly increases. The ,' .~ ,, ,~ ' I
. I
~3~
additional moisture reduces the combustlbility of the coal and increases the amount of residual ash created during the combustion of the coal.
Other techniques have been developed to agglomerate coal particles without increasing the moisture sorption of the particles into an agglomerated particle. For e~ample, asphalt pitch, residual oil; coal tar, and starch have been used to bind coal particles. In U. S. Patent Number 4,126,426 to Verschuur (1978), a slurry of coal particles was divided~into a first fraction of small particles and a second fractlon of large particles. 10 parts of a liquid hydrocarbon binder was added to 90 parts of the first fraction, and the first fraction was recombined with the second fraction. The resulting agglomerate formed by this process reduces the amo~mt of moisture absorbed by the coal after the excess water has been removed. However, the resulting agglomerate is susceptible to breakage and to abrasive wear which degrades the shape of the agglomerate during transportation of the coal.
' ~0 Currently available processes for agglomerating coal ¦
particles are not commercially practical due to several factors. Processes which use large amounts of organic fiber to agglomerate coal particles are subject to moisture sorption, and processes which combine a hydrocarbon binder with coal particles are subject to breakage. Other processes which combine large quantities of organic fiber with large quanti-i&s of a ,.
3L3~
hydro~arbon binder are expensive to use and may not adequately reduce moisture sorption to desirable levels. Therefore, a need exists for an improved composition and process which agglomerates fine coal particles while ma~imi2ing the strength and moisture repellency of the agglomerated particles.
SUMMARY OF THE IN~ENTION
The present invention furnishes an improved composition lU and process for agglomerating fine coal particles which improves the strength of the agglomerated particles while preventing the sorption of an undesirable amount of moisture. The composition comprises between one and five percent fiber by weight of coal combined with between three and twelve percent hydrophobic binder by weight of coal. In a preferred embodiment of the invention, the fiber is organic.
The improved process is practiced by dispersing on the coal a hydrophic binder of between three and twelve percent by weight - 20 o~ coal. Subsequently, between one and five percent of fiber by weight of coal is mixed with the coal and binder, and the coal, .. . .
binder, and fiber are formed into an agglomerate. In an alternative embodiment of the invention, moisture is removed ~
from the coal particles until the moisture con;tent i5 less than .
tweLve percent. In another embodiment of the invention, the coal, binder, and fiber are nli~ed with additional coal particles having a diameter greater than 590 microns before the agglomerate is formed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As set forth above, known processes do not permit the economic manufacture of a coal agglomerate which has acceptable mechanical strength and moisture repellency. The present .
invention accomplishes these objectives by adding between three and twelve percent by weight of a hydrophobic binder and between one and five percent by weight of organic fiber to the coal.
To practice the invention, the moisture content of fine coal is modified to a selected amount which is preferably between t~o and twelve percent by wei~ht. Moisture can be added by spraying water onto the coal or can be removed by f~Ltration or thermal drying techniques well-known in the art.
29 Subsequently, a hydrophobic binder such as fatty acid residues, sulphite lignin, asphalt, pitch, tar or other hydrocarbon is added to the coal. Preferably, the hydrophobic binder is between two and twelve percent by weight of the coal In one embodiment of the invention, the binder can be:added to the coal before the moisture is removed from or added to the coal. The binder should be adequately mixed with the coal to obtain uniform distribution of the binder. The mixing can be .~ , . . . .
I
I
6~)~
accomplished by techniques well-known in the art which include auger mixing or ribbon blending. If the binder is a petroleum distillation residue such as pitch~ the binder can be heated and sprayed onto the coal with an atomizing nozzle.
Following the addition of the binder to the coal, a fiber having a weight between one and five percent of the coal is mixed with the coal and binder. The fiber can be one of many materials and may be organic or inorganic in nature. Examples of organic fiber include shredded paper, pulverized bark, or wood was~e produced from a sawmill or lumber dressing plant.
Scrap newsprint is useful because it contains a lov amount of mineral flller. In addition, scrap cra~t or sulphite paper may also be used if the combustion of such paper does not result in an unacceptable amount of ash. The waste fiber can be milled by a blade mill or by beaters to separate individual fibers and fiber bundles. During the milling process, the comminuted fibers may be separated by well-known pneumatic classification techniques. Waste fiber having an excessively high mois-ture 20 content may ~e partially dried before the fiber is milled. ~ ;
:, , . . .
Following the addition of the fiber to the coal and binder, the mixture is formed into an agglomerate by techniques well-known in the art. For example, the mixture may be Eormed or compressed into briquets, pellets, or may be extruded into other shapes. Preferablys the agglomerate forming pressure should exceed 8000 psi. In a puck-forming process disclosed in ~35~5~
U. S. Patent Number 4,420,404 to Dravo, a flotation concentrate slurry is thickened and then is loaded into an enclosed compression chamber. A compressive force expresses fluid from the chamber until a coarse puck is formed.
The following three examples are presented to illustrate tests which demonstrate the advantages of the current invention.
Exc~mple 1 In this test, fine coal flotation concentrate (85%
passing a 200 mesh screen) was filtered,.air dried to 4%
moisture, and mechanically mixed with a commercial asphalt emulsion (65% asphalt, 35% water) irl an amount equal to 670 asphalt by weight. To this mixture was added 5% by weight of commercial shredded newsprint, and the whole mixture was dispersed with an auger mixer. Portions of the mixture were then formed at 10,000 psi pressure in a 1/2" diameter cylindrical die. Similar mixtures were prepared without fiber and according to the methods disclosed by the U~ S.
Patents issued to Decker and Reinold tsee above). The results of the tests may be summarized as follows:
., .
.. ..
~L31~
--8~
COMPOSITION PRODUCT MOISTURE COMPRESSIVE
_ SORPTION, WT.%STRENGTH (lb) 1. 6% asphalt, 5% fiber 2.1 174 2. 6% asphalt 14.6 68 3. Method of Decker 41.7 462 4. Method of Reinold 28.9 207 (5% fiber) As demonstrated by these results, Composition I shows an improvement oE L50% over Composition 2 in strength due to the added fiber and also shows a large reduction in moisture sorption (14.6% sorption for asphalt binder ODly, VS. 2.1 sorption for the ~lethod of the present invention). ~he extremely low water sorption in this test is considered due to action of the dry fiber in "blotting" residual moisture from coal surfaces, thereby allowing very effective wetting of the naturally hydrophobic coal surface by the asphalt binder. :
Composition 3 showed very high initial strength (462 lb load to failure vs. 174 lb for Composition 1~, but water sorption is considered to be unacceptably high at 41%.
Composition 3 also contains large amounts of additive materials (20% fiber, 12% asphalt) which are expensive when compared to the market value of the final coal product.
Composition 4 showed a compressive strength which was 18% greater than that of Composition 1. ~owever, the water sorption of Composition 4 was significantly greater than for ' ~L3~
_9_ Composition 1. Therefore, Composition 1 demonstrated the most favorable combination of co~pressive strength and resistance to moisture sorption.
Example 2 Agglomerates were prepared from a coal slurry pursuant 10 to the method disclosed by Dravo (see above). Samples were prepared with no additive, with asphaltic pitch binder as an additive, and with three different amounts of fiber combined with pitch binder. Test results were as follows:
:
, ....
SAMPI.E ~ FORMING AS FORMED MOISTURE DROP FILTRATE
PARTICLE SIZE ADDITIVES -PRESSURE MOISTURE RESORPTION TEST LOSS
(kpsi) (%) (%) (%<1/4") (%:-of :
~ coal) (Scavenger Concentrate 100 mesh x 0, 20 60% - 325 mesh~ 1. none 16 14.2 9.4 10.1 20.1 2. Pitch, S~ 16 10.1 6.1 7.8 22.0 3. P,itch, 5% 14 11.3 6.8 8.1 ~21.4 4. Pitch, 5% 14 13.3 6.~ 7.4 1.2 Fiber, 1%
- -- - f 5. Pitch, 5% 14 13.3 7.3 4.2 2.1 Fiber, 2%
~
6. ~itch, S% 14 14.6 7.8 1.4 2.7 Fiber~ 3 ~ , .
i With respect to agglomerate strength, a modified ASTM
drop/shatter test was used in this case (increasing strength :
i ~3~
--10-- .
is indicated by decreasing amounts of 1/4" material). As demonstrated by Compositions 4 - 6, increasing levels of fiber additive in the 1-3% range progressively improved the strength of the agglomerate as compared to the strength of agglomerate formed without binder or with pitch as a binder.
, ~-: .
, :
In Composition 29 the reduced moisture sorption due to fiber is not observed as in Example 1. Rather, the tests - .
indicate an increase in moisture sorption associated with increasing levels of fiber additive. ~owever, the amount of filtrate loss during formation oE the agglomerate was significantly reduced with the addition of between one and three percent of fiber to the composition. ~Therefore, the tests demonstrate that the addition of fiber and binder in .
Compositions 4 - 6 improved the strength of the agglomerate, reabsorbed less moisture than an agglomerate formed without any additives, and signlficantly lessened the percentage of ~ ;
coal lost due to filtration during agglomerate formation.
Example 3 Coarse (1/4" x Z8 mesh) coal was blended with the flotation product slurry used in Example 2 to model a consolidated product consisting of coarse and fine coal.
The consolidated coal was then agglomerated by the same method used in Example 2. Test results were as follows:
5~
S~MPLE & FORMING AS FORMED MOISTURE DROP FILTRATE
PARTICLE SIZE ADDITIVES PRESSURE MOISTURE RESORPTION TEST LOSS
(~psi) (~) (%) (%<1~4") (% of coal) Blended Gravity Pitch, 5% 14 8.1 5.2 6.0 3.9 & Flotation Fiber, 1%
Product Fiber t 1% 1/4" x 0, 2870 - 325 Mesh ~.
Compared with test 4 of Example 2, the amount of mo;sture resorbed was reduced from 6.9 to 5.2%. The strength ;mproved from 7.4 to 6.0 (%<1/4"), although filtrate loss increased from 1.2% to 3.9%. This data demonstrates that satisfactory agglomerates can be formed from a combination of coarse coal, such as coal having a particle si~e greater than 590 microns, together with a mixture of fine coal, binder, and fiber.
The present invention discloses a unique composition and process for agglomerating coal partlcles such as coal fines. The composition is sufficiently strong to resist breakage while resisting unacceptable molsture sorption which would require drying of the coal. The composltion can be ~ ~
25 compressed or otherwise formed into agglomerates by techniques ¦
well-known in the art. Because the cost of fiber and~
.
~3~560~
hydrophobic binder often e~ceeds the cost of coal~ the invention improves the economics of agglomerating coal particles by significantly reducing the amount of fiber and binder added to tne coal.
It should be apparent from the foregoing that many other variations of the composition and process described herein may be made without departing from the scope of the present invention. Accordingly, it should be understood that the -~
10 embodiments set forth herein are illustrative and should not :
limit the scope of the invention.
.': ;: -~; :
i With respect to agglomerate strength, a modified ASTM
drop/shatter test was used in this case (increasing strength :
i ~3~
--10-- .
is indicated by decreasing amounts of 1/4" material). As demonstrated by Compositions 4 - 6, increasing levels of fiber additive in the 1-3% range progressively improved the strength of the agglomerate as compared to the strength of agglomerate formed without binder or with pitch as a binder.
, ~-: .
, :
In Composition 29 the reduced moisture sorption due to fiber is not observed as in Example 1. Rather, the tests - .
indicate an increase in moisture sorption associated with increasing levels of fiber additive. ~owever, the amount of filtrate loss during formation oE the agglomerate was significantly reduced with the addition of between one and three percent of fiber to the composition. ~Therefore, the tests demonstrate that the addition of fiber and binder in .
Compositions 4 - 6 improved the strength of the agglomerate, reabsorbed less moisture than an agglomerate formed without any additives, and signlficantly lessened the percentage of ~ ;
coal lost due to filtration during agglomerate formation.
Example 3 Coarse (1/4" x Z8 mesh) coal was blended with the flotation product slurry used in Example 2 to model a consolidated product consisting of coarse and fine coal.
The consolidated coal was then agglomerated by the same method used in Example 2. Test results were as follows:
5~
S~MPLE & FORMING AS FORMED MOISTURE DROP FILTRATE
PARTICLE SIZE ADDITIVES PRESSURE MOISTURE RESORPTION TEST LOSS
(~psi) (~) (%) (%<1~4") (% of coal) Blended Gravity Pitch, 5% 14 8.1 5.2 6.0 3.9 & Flotation Fiber, 1%
Product Fiber t 1% 1/4" x 0, 2870 - 325 Mesh ~.
Compared with test 4 of Example 2, the amount of mo;sture resorbed was reduced from 6.9 to 5.2%. The strength ;mproved from 7.4 to 6.0 (%<1/4"), although filtrate loss increased from 1.2% to 3.9%. This data demonstrates that satisfactory agglomerates can be formed from a combination of coarse coal, such as coal having a particle si~e greater than 590 microns, together with a mixture of fine coal, binder, and fiber.
The present invention discloses a unique composition and process for agglomerating coal partlcles such as coal fines. The composition is sufficiently strong to resist breakage while resisting unacceptable molsture sorption which would require drying of the coal. The composltion can be ~ ~
25 compressed or otherwise formed into agglomerates by techniques ¦
well-known in the art. Because the cost of fiber and~
.
~3~560~
hydrophobic binder often e~ceeds the cost of coal~ the invention improves the economics of agglomerating coal particles by significantly reducing the amount of fiber and binder added to tne coal.
It should be apparent from the foregoing that many other variations of the composition and process described herein may be made without departing from the scope of the present invention. Accordingly, it should be understood that the -~
10 embodiments set forth herein are illustrative and should not :
limit the scope of the invention.
.': ;: -~; :
Claims (17)
1. An improved coal composition, comprising:
a quantity of fine coal particles having a known weight;
fiber in the range of 1.0 and 5.0 percent by weight of the coal; and hydrophobic binder in the range of 3.0 and 12.0 percent by weight of the coal.
a quantity of fine coal particles having a known weight;
fiber in the range of 1.0 and 5.0 percent by weight of the coal; and hydrophobic binder in the range of 3.0 and 12.0 percent by weight of the coal.
2. A composition as recited in Claim 1, wherein the weight of the binder exceeds the weight of the fiber.
3. A composition as recited in Claim 1, wherein the fiber is organic.
4. A composition as recited in Claim 1, wherein the average diameter of the coal particles is less than 590 microns.
5. An improved coal composition resistant to breakage and moisture sorption, comprising:
fine coal particles having a known weight and having a moisture content less than 12.0 percent;
organic fiber in the range of 1.0 and 5.0 percent by weight of the coal; and hydrophobic binder in the range of 3.0 and 12.0 percent by weight of the coal.
fine coal particles having a known weight and having a moisture content less than 12.0 percent;
organic fiber in the range of 1.0 and 5.0 percent by weight of the coal; and hydrophobic binder in the range of 3.0 and 12.0 percent by weight of the coal.
6. A composition as recited in Claim 5, wherein the weight of the fiber is less than the weight of the binder.
7. A composition as recited in Claim 6, wherein the combined weight of the fiber and binder is less than 12.0 percent of the weight of the coal.
8. A composition as recited in Claim 5, wherein the average diameter of the coal particles is less than 590 microns.
9. A process for forming an improved coal composition from a quantity of fine coal particles having a known weight, comprising the steps of:
dispersing on the coal particles hydrophobic binder of an amount between 3.0 and 12.0 percent by weight of the coal;
mixing fiber, of an amount between 1.0 and 5.0 percent by weight of the coal, with the coal and binder;
and forming the coal, binder, and fiber into an agglomerate.
dispersing on the coal particles hydrophobic binder of an amount between 3.0 and 12.0 percent by weight of the coal;
mixing fiber, of an amount between 1.0 and 5.0 percent by weight of the coal, with the coal and binder;
and forming the coal, binder, and fiber into an agglomerate.
10. A process as defined in Claim 9, wherein said agglomerate is formed by a force exceeding 8000 psi.
11. A process as defined in Claim 9, wherein the fiber is mixed with the coal particles before the binder is added.
12. A process as defined in Claim 9, wherein the coal particles generally have a diameter less than 590 microns.
13. A process as defined in Claim 9, further comprising the step of adding coal particles having a diameter greater than or equal to 590 microns to the initial coal particles, binder, and fiber before the agglomerate is formed.
14. A process for forming an improved coal composition resistant to breakage and to moisture sorption, comprising the steps of:
dispersing, on a quantity of coal particles having a known weight and having an average diameter less than 590 microns, hydrophobic binder of an amount between 3.0 and 12.0 percent by weight of the coal;
mixing fiber, of an amount between 1.0 and 5.0 percent by weight of the coal, with the coal and binder;
adding coal particles of an average diameter greater than or equal to 590 microns to the composition;
and forming the coal particles, binder, and fiber into an agglomerate by a force which exceeds 8000 psi.
dispersing, on a quantity of coal particles having a known weight and having an average diameter less than 590 microns, hydrophobic binder of an amount between 3.0 and 12.0 percent by weight of the coal;
mixing fiber, of an amount between 1.0 and 5.0 percent by weight of the coal, with the coal and binder;
adding coal particles of an average diameter greater than or equal to 590 microns to the composition;
and forming the coal particles, binder, and fiber into an agglomerate by a force which exceeds 8000 psi.
15. A process for forming an improved coal composition resistant to breakage and to moisture sorption from a coal slurry containing coal particles suspended in water, comprising the steps of:
removing water from the coal slurry until the coal has a moisture content less than 12.0 percent;
dispersing on the coal a hydrophobic binder of an amount between 3.0 and 12.0 percent by weight of the coal;
mixing fiber, of an amount between 1.0 and 5.0 percent by weight of the coal, with the coal and binder;
and forming the coal, binder, and fiber into an agglomerate having a selected shape.
removing water from the coal slurry until the coal has a moisture content less than 12.0 percent;
dispersing on the coal a hydrophobic binder of an amount between 3.0 and 12.0 percent by weight of the coal;
mixing fiber, of an amount between 1.0 and 5.0 percent by weight of the coal, with the coal and binder;
and forming the coal, binder, and fiber into an agglomerate having a selected shape.
16. A process as recited in Claim 15, further comprising the step of mixing coal particles having a diameter greater than or equal to 590 microns to the coal particles, binder, and fiber before the agglomerate is formed.
17. A process as recited in Claim 15, wherein the coal particles, binder, and fiber are compressed into an agglomerate by a force which exceeds 8000 psi.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US76128385A | 1985-08-01 | 1985-08-01 | |
| US761,283 | 1985-08-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1305608C true CA1305608C (en) | 1992-07-28 |
Family
ID=25061769
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 508993 Expired CA1305608C (en) | 1985-08-01 | 1986-05-13 | Composition and process for agglomerating coal particles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1305608C (en) |
-
1986
- 1986-05-13 CA CA 508993 patent/CA1305608C/en not_active Expired
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