111111111111111111111111111111111111111111111111111111111111111111111111111
US007913939B2
(12) United States Patent
French et al.
(10) Patent No.:
(45) Date of Patent:
US 7,913,939 B2
Mar. 29,2011
(73) Assignee: GTL Energy, Ltd., Unley SA (AU)
(54) METHOD TO TRANSFORM BULK
MATERIAL
(75) Inventors: Robert R. French, Wellington, CO
(US); RobertA. Reeves, Arvada, CO
(US)
12/1976 Cole et al.
9/1977 Cole et al.
11/1977 Cole et al.
8/1978 Cole et al.
9/1979 Slater et al.
7/1980 LaDelfa et al.
9/1980 Bodle et al.
9/1980 Perch et al.
12/1981 Wiese et al.
1/1982 Blodgett et al.
1/1982 Baron et al.
2/1983 Nielsen
(Continued)
3,996,026 A
4,047,898 A
4,057,399 A
4,104,035 A
4,166,802 A
4,212,112 A
4,223,449 A
4,225,391 A
4,304,572 A
4,309,109 A
4,309,190 A
4,372,749 A
FOREIGN PATENT DOCUMENTS
W02005028977 3/2005
OTHER PUBLICATIONS
WO
Apr. 28, 2006
( *) Notice: Subject to any disclaimer, the term ofthis
patent is extended or adjusted under 35
U.S.c. 154(b) by 291 days.
(21) Appl. No.: 11/380,884
(22) Filed:
(65) Prior Publication Data
US 2007/0023549 Al Feb. 1,2007
U.S. Appl. No. 12/185,025, filed Aug. 1, 2008, French, et al.
(Continued)
15 Claims, 2 Drawing Sheets
Primary Examiner - Mark Rosenbaum
(74) Attorney, Agent, or Firm - Sheridan Ross, P.c.
The invention provides low-cost, non-thennal methods to
transfonn and beneficiate bulk materials, including low rank
coals such as peat, lignite, brown coal, subbituminous coal,
other carbonaceous solids or derived feedstock. High pressure
compaction and comminution processes are linked to
transfonn the solid materials by eliminating interstitial, capillary,
pores, or other voids that are present in the materials
and that may contain liquid, air or gases that are detrimental
to the quality and perfonnance ofthe bulk materials, thereby
beneficiating the bulk products to provide premium feedstock
for industrial or commercial uses, such as electric power
generation, gasification, liquefaction, and carbon activation.
The handling characteristics, dust mitigation aspects and
combustion emissions ofthe products may also be improved.
Related U.S. Application Data
(60) Provisional application No. 60/676,621, filed on Apr.
29,2005.
(51) Int. Cl.
B02e 19/00 (2006.01)
(52) U.S. Cl. 241/3; 241/19; 241/29; 241/101.4
(58) Field of Classification Search 241/3, 101.4,
241/29, 19
See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
286,520 A 10/1883 Andrus
2,610,115 A 9/1952 Lykken
3,114,930 A * 12/1963 Oldham et al. 241/68
3,619,376 A 11/1971 Pateletal.
3,643,873 A * 2/1972 George 241/3
3,822,827 A * 7/1974 Clark 241/3
(57) ABSTRACT
44
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US 7,913,939 B2
Page 2
OTHER PUBLICATIONS
* cited by examiner
International Search Report for International (PCT) Patent Application
No. PCTIUS06/16319, mailed Aug. 12,2008.
Written Opinion for International (PCT) Patent Application No.
PCTIUS06/16319, mailed Aug. 12, 200S.
International Preliminary Report on Patentability for International
(PCT) Patent Application No. PCTIUS06/16319, mailed Mar. 19,
2009.
Examiner's First Report for Australian Patent Application No. 2006242458,
mailed Dec. 11,2009.
Examination Report for New Zealand Patent Application No.
562623, mailed Sep. 7, 2009.
Examiner's First Report for Canadian Patent Application No.
2606023, mailed Apr. 29, 2010.
u.s. PATENT DOCUMENTS
4,533,460 A 8/1985 Ho
4,726,531 A 2/1988 Stasser
4,782,747 A 11/1988 Unger et al.
5,005,770 A * 4/1991 Suessegger 241/19
5,067,968 A * 11/1991 Davidson et 31 44/550
5,251,824 A * 10/1993 Adelmann 241/3
5,361,513 A 11/1994 Woessner
5,462,425 A 10/1995 Kuss et al.
5,509,612 A * 4/1996 Gerteis 241/101.4
5,658,357 A 8/1997 Liu et al.
5,667,642 A 9/1997 Luthi
5,862,746 A 1/1999 Bielfeldt
5,876,648 A 3/1999 Strasser et al.
5,902,456 A 5/1999 Sundqvist et al.
6,054,074 A 4/2000 Wu et al.
6,148,599 A * 11/2000 McIntosh et al. 60/781
6,311,849 Bl 11/2001 Sbaschnigg et al.
6,338,305 Bl 1/2002 McHenry et al.
6,461,505 Bl 10/2002 Danielsson et 31.
6,889,923 B2 * 5/2005 Gutierrez et al. 241/3
7,128,767 B2 10/2006 French et al.
2006/0112617 Al
2006/0180525 Al
2008/0222947 Al
6/2006 Clark et al.
8/2006 Watters et al.
9/2008 French et al.
u.s. Patent Mar. 29,2011 Sheet 1 of2 US 7,913,939 B2
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u.s. Patent Mar. 29,2011 Sheet 2 of2 US 7,913,939 B2
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US 7,913,939 B2
1
METHOD TO TRANSFORM BULK
MATERIAL
2
economic disincentives and production hazards associated
with thermal drying techniques.
SUMMARY OF THE INVENTION
This invention provides new beneficiation methods that
can be applied to transform a wide range ofbulk materials and
that does not use thermal energy or adversely alter the chemical
nature of these materials. This methodology takes advan-
10 tage of the fact that most of the gas and water is held in
microscopic voids in the structure of the bulk materials and
especially in low rank coals (LRCs). Comminution and high
compaction forces are applied to transform the structure of
these bulk materials by destroying most ofthe internal voids
15 to release the air, gas, and liquids and preventing their recapture
by sorption. By reducing or destroying these voids, this
methodology produces a dense, compact, solid material. In
the case of coal transformation this methodology produces a
fuel with higher energy and fewer deleterious components.
20 The end products ofthese techniques may be customized for
the mining, transportation and consumer industries.
The methods and apparatus disclosed herein exert extreme
compaction forces on prepared LRC feedstocks in order to
destroy the interstitial, capillary, pores and other voids, thus
25 transforming the physical characteristics of LRC and other
similar bulk materials. Air and gas are expelled and water is
transferred to the surfaces of the LRC particles where it is
removed by mechanical means or during pneumatic transfer
to produce clean and compact final products.
Unlike many expensive batch processes that use thermal
energy and low compaction forces to heat and squeeze the
coal, the present invention uses no thermal energy and operates
in a continuous mode. These continuous processes result
in higher throughputs than batch processing, significantly
35 lower operating costs as no thermal energy is required, and
greater safety as no external heat is applied. Additionally, the
products formed are more stable as minimal rehydration of
the dried products takes place and therefore less dust and fines
are generated compared to thermal drying techniques. The
40 environmental impact ofhigh temperature drying techniques
are substantially reduced by the processes disclosed herein
because the organic rich effluents that are produced by thermal
drying are minimized or eliminated by the techniques of
the present invention.
These inventive processes include compaction and comminution
of the bulk coal feed material, and multiple stages of
compaction and comminution can be used to achieve the
desired heat content for either existing or new coal-fired
projects. The products can then be agglomerated to a suitable
50 top size for transportation or alternate uses.
In one preferred configuration, the bulk starting material is
comminuted then compacted between counter-rotating rolls.
In this process gases may be dissipated as internal voids
within the material are destroyed, and expelled liquids are
55 separated from the solids by mechanical removal in liquid
phase from the rolls, and in gas phase during transport to a
subsequent processing that may include additional cycles of
comminution and compaction.
One embodiment is a method of transforming a bulk start-
60 ing material including compacting a bulk material and then
comminuting the compacted bulk material to form a comminuted
material. The comminuted material may have fewer
void spaces than the bulk starting material. The bulk material
useful in these methods is composed of particles that hold
65 gases or liquids within void spaces within the solid particles.
Typically, the bulk material is a carbonaceous material such
as bituminous coal, peat, low-rank coals, brown coal, lignite
FIELD OF THE INVENTION
CROSS REFERENCE TO RELATED
APPLICATION
BACKGROUND OF THE INVENTION
This invention provides low-cost, non-thermal methods to
transform and beneficiate bulk materials, including low rank
coals, to provide premium feedstock for industrial or commercial
uses.
Low Rank Coals (LRC) comprise almost 50% oftotal coal
production in the United States, and about one-third of the
coal produced worldwide. LRCs are characterized by their
high levels of porosity and their water content which is
retained in three basic forms: interstitial, capillary and
bonded. Removal of the voids in which air, gas, and water
reside in these coals requires primary comminution followed
by compaction and higher energy inputs as transformation
becomes more rigorous. The excess constituents, including 30
air, gas, and water that would otherwise dilute the combustible
material, are progressively expelled as interstitial voids
between particles, and pores contained in the particles are
eliminated.
The utility and gasification industries have long recognized
the benefits ofreducing these constituents in coal. Numerous
beneficiation systems of varied technical complexity have
been designed, but almost all use some form of thermal
energy such as flue gas, steam, hot oil, hot water or the like, to
remove water and some organic material (see, Davy-McKee,
Inc. Comparision of Technologies for Brown Coal Drying,
Coal Corporation ofVictoria, Melbourne Australia (1984)).
The technical, economic and environmental benefits realized
by the use ofthese thermal drying procedures have been well
documented and include increased power plant efficiency, 45
increased generating efficiency, reduced greenhouse gas
emissions, reduced dependence on carbon dioxide disposal
systems, increased value of the LRC resources and reduced
parasitic power consumption. But while these thermal beneficiation
systems are technically effective, they are also
expensive to build, costly to operate, site restricted, and must
compete with other market opportunities for the energy they
consume.
Additionally, thermal drying can produce coal dust that
leads to unacceptably dangerous fuel products. High temperature
thermal drying of coal, especially LRCs, largely
alters the chemical characteristics ofthe fuel. The dried product
is more reactive to air and may rapidly rehydrate, thus
providing greater opportunity for spontaneous combustion
and catastrophic fires. High volumes of coal fines and dust
associated with thermally dried LRC create handling problems
and product losses during rail transportation and handling,
and some thermal drying systems are unable to process
LRC fines ofless than one-quarter inch and require alternative
processing or result in substantial waste.
Thus, new coal benefication techniques are needed that can
realize the substantial benefits of drying LRCs without the
This application claims priority under 35 U.S.c. §119(e) to
U.S. Provisional Patent Application Ser. No. 60/676,621 filed
Apr. 29, 2005, which is incorporated herein in its entirety by
this reference.
US 7,913,939 B2
3 4
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION OF THE INVENTION
FIG.! shows a schematic drawing ofa plan view ofa single
absorber roll useful in an absorptive counter-rotating roll
assembly.
FIG. 2 shows an elevation at sectionA-A ofthe roll ofFIG.
2.
FIG. 3 shows an elevation at section B-B ofthe roll ofFIG.
2.
FIG. 4 shows a schematic diagram of processing procedures
of the present invention.
The present invention is drawn to a process that efficiently
transfonns bulk materials such as low rank coal (LRC) into
economically useful feedstocks with lower environmental
impact and hazards production than has previously been possible.
Additionally, apparatuses useful for carrying out these
transfonnative processes on bulk materials are described
herein.
Bulk materials contain interstitial spaces between the particles
of bulk material as well as capillary or pore spaces that
exist within each individual bulk particle. For the purposes of
this disclosure, these interstitial, capillary and pore spaces are
referred to collectively as "void" space within the bulk material.
The transfonnation processes ofthe present invention are
perfonned by applying compaction and comminution forces
to a bulk material sufficient to collapse and destroy these void
spaces that exist within the bulk materials. These processes
expel substances, including gases and liquids that reside in
In another embodiment, the comminuted bulk material is
subjected to another compression step. This second compression
may be designed to specifically remove liquids from the
surfaces of the materials. In this embodiment, comminuted
material is compressed using compaction machinery that
absorbs liquids present on the transfonned materials. This
compaction is prefonned at a compaction pressure between
about 3,000 psi and about 15,000 psi. This compaction to
remove additional liquids present is conducted by contacting
10 the comminuted material with a porous compaction surface.
This porous compaction surface may absorb liquids from the
comminuted materials. The separated liquids may be carried
away from the materials. Preferably, this compacting is performed
using counter-rotating rolls composed of porous
15 materials. These porous counter-rotating rolls may absorb
liquid into the porous material to be pulled away from the
comminuted materials and collected or discharged to the
environment. Liquids may be removed from the surface ofthe
porous counter-rotating rolls with a scraper blade. Bulk mate-
20 rial exiting the porous counter-rotating rolls may have a lower
liquid content than the comminuted feed material.
Another embodiment described herein is an absorptive roll
assembly that can be used in the compaction between two
counter-rotating rolls to remove liquids from a bulk material.
25 These rolls are composed of a central shaft supported by
bearings at each end ofthe central shaft and endpieces affixed
around the central shaft between the bearings. Liquid receptors
are affixed around the central shaft between the end
pieces. The liquid receptors contain an absorptive porous
30 material that canwick liquid from a bulk material compressed
against the porous material. The end pieces preferably contain
weep holes that direct liquids absorbed in the porous rolls
towards the ends of the central shaft and away from the bulk
materials. Preferably, liquid receptors can be independently
35 detached and replaced on the central shaft.
and subbituminous coal or carbonaceous materials that have
been pre-processed using beneficiation procedures such as
thennal drying, washing, biological and chemical beneficiation,
dry screening or wet screening. The bulk material may
also be gypsum, coke, expandable shales, oil shale, clays,
montmorillonite, and other naturally-occurring salts including
trona, nacolite, borite, and phosphates. When undergoing
compaction at high pressures, gases and/or liquids are forced
from void spaces in the bulk material.
In one embodiment, the bulk material is first crushed or
broken to an average particle top size between about 0.006
inch and about 1 inch prior to moving the bulk material to the
compacting machinery. If needed, the bulk material is stored
in a collection vessel, such as a surge bin, after crushing and
prior to compacting, and this allows the bulk material to be
fed at a controlled rate to compacting machinery. The bulk
material may be frozen, chilled or heated ifdesired. However,
the bulk material is preferably processed and stored at ambient
temperature to minimize energy expenditure and processing
costs and to maintain liquids and gasses in the bulk materials
in a liquid or gaseous state to facilitate their removal
from the bulk materials during processing.
The bulk material is subjected to a compaction pressure of
at least about 3000 psi, and typically at a pressure as high as
about 80,000 psi. Preferably, the bulk material is subjected to
a pressure between about 20,000 psi and about 60,000 psi
during compaction, and more preferably, the bulk material is
subjected to a pressure of about 40,000 psi during compaction.
The compaction pressure is applied for short time periods
of between about 0.001 seconds and about 10 seconds.
In one embodiment, the compacting is performed by feeding
the bulk material between two counter-rotating rolls
aligned in proximity to one another. The compaction pressure
is applied to the bulk material as the material is fed between
the rolls. In this embodiment, the void spaces within the bulk
materials may be crushed and eliminated from the materials
as the material passes between the counter-rotating rolls forcing
liquids and gases from the bulk material. These counterrotating
rolls may be cleaned with companion rollers, squeegees
or blades. The counter-rotating rolls may be driven by a 40
reducer and an electric motor at a speed that provides a bulk
material residence time within the compression zone of the
rollers ofbetween about 0.001 seconds and about 10 seconds.
The bulk materials ofthis embodiment are compressed into a
ribbon that exits the rollers and breaks or fractures into large 45
compacts.
Compressed materials are comminuted to reduce the particle
size of compacts that have been produced by the high
compaction pressures described above. The comminuting
may include cutting, chopping, grinding, crushing, milling, 50
micronizing and triturating the compressed materials. Preferably,
the comminuting methods used can accept and process
compressed materials at a rate equal to the rate at which
the compacts exit the compacting machinery. If this is not
convenient, the compressed materials can be collected and 55
stored or held briefly until they are introduced to the comminuting
machinery at a controlled rate. The compressed material
is comminuted to an average particle top size between
about 0.006 inch and about 1 inch. The comminuted material
may then be dried, packaged, stored, pneumatically trans- 60
ferred to another facility for additional processing such as
separation of solids and gases, and the like.
These processes of compacting and comminuting the bulk
material may then be repeated as many times as desired to
continue the transformation of the material, further eliminat- 65
ing void spaces and the liquids or gases therein with each
successive round of compaction and comminution.
US 7,913,939 B2
5 6
The bulk materials are preferably compacted at ambient
temperature although cold or even partially frozen materials
may be successfully processed. If there is a liquid absorbed
within or adsorbed to the bulk materials, the materials should
be warm enough to drive the liquid from void spaces in the
material and this is most efficient if the temperature of the
compacted materials is sufficiently high to keep the liquids
from freezing. Similarly, the products may be wanned or hot
at the time ofcompaction although little transformative effect
10 is gained by providing heated materials to the compaction
step. Most preferably, the bulk materials are compacted at an
ambient temperature at which any liquids present in the void
spaces remain in a liquid or gaseous state thereby facilitating
their removal from the bulk materials.
The compaction pressure is applied to the bulk materials
for the time necessary to transfonn the feed. Typically, the
compaction pressure is applied for a period of at least 0.001
seconds. The compaction pressure may be applied to the bulk
material for as long as about 10 seconds or longer. Preferably
20 the compaction pressure is applied for a time period between
about 0.1 seconds and about 1 second.
In one embodiment, the compaction is carried out by feeding
the bulk material through two counter-rotating rolls in
proximity to one another so as to provide the appropriate
25 compaction pressure to the bulk material. The two counterrotating
rolls apply mechanical compaction forces to the bulk
feed material by compacting the material between a specified
gap between the rolls with a force that is sufficient to transform
the feed material, while allowing liquids and/or gases
30 within the feed material to be separated from the compacted
product as void spaces occurring in the material are eliminated.
The counter rotating rolls used preferably provide a
compaction pressure to the bulk material of at least 3000 psi
and more preferably the rolls are adjustable within the range
35 ofabout 3000 psi and about 80,000 psi as described above. As
the bulk materials are compacted between the counter-rotating
rolls, the rolls may be cleaned with companion rollers,
squeegees, blades or the like to draw away liquids or debris
such as roll scrapings separated from the bulk materials by the
40 application of the compacting pressure. The two counterrotating
rolls providing the compaction pressure to the bulk
materials may be driven by a suitable reducer and electric
motor at a circumferential speed that provides the desired
process capacity and material residence time within the com-
45 pression zone. In one embodiment, the relative rotation rate of
the compaction rolls may be unity. Alternatively, the compaction
rolls may be rotated asynchronously to provide a shearing
force as well as compaction force to the bulk material. In
this instance, the additional shearing force combined with the
50 high pressure compaction forces may further reduce the void
spaces in the bulk material.
The compacted materials, or compacts, exit the first compaction
step in a compressed form that has fewer or lower
void space compared to the bulk material applied to the com-
55 paction step. In the instance in which the compaction processes
is performed using two counter-rotating rolls, the compacts
exit the compacting rolls as a ribbon that will
subsequently break into compacted pieces of bulk material
that typically have a top size between about 0.5 inch and about
60 10 inches.
The compacted products exiting the compaction process
are then comminuted. Preferably, the comminution is sufficient
to reduce the particle size of the material. Any suitable
means of breaking up or crushing the compacted products to
65 reduce the particle size is useful at this stage of the transformation
process. Comminution in its broadest sense is the
mechanical process ofreducing the size ofparticles or aggrethe
void spaces from the bulk material. In these transfonnation
processes, the substances are separated from the bulk
material.
These processes include compaction and comminution of
the bulk materials followed by sorption of liquids from the
comminuted products. The comminuted products may then
be subjected to further evaporative drying steps to complete
the initial transformation of the bulk products. The transformed
products may optionally be subjected to subsequent
rounds of these transfonnation steps.
Bulk materials suitable for transfonnation in the processing
procedures ofthe present inventionmay include any solid
feed materials that hold gases or liquids within void space or
on the surface ofthe solids. These materials may be naturally
occurring carbonaceous materials including bituminous coal, 15
peat and low-rank coals (LRCs), which include brown coal,
lignite and subbituminous coal. The bulk feed material may
similarly contain carbonaceous materials that have undergone
prior processing such as bituminous coal, peat, and
LRCs that have undergone pre-processing using thermal drying
methods, washing processes, biological beneficiation
methods, or other pre-treatment processes, or dry or wet
screening operations. Additionally, the bulk material may be
gypsum, coke, expandable shales, oil shale, clays, montmorillonite,
and other naturally-occurring salts including trona,
nacolite, borite and phosphates.
Liquids or gasses commonly reside in the void spaces of
these bulk materials or are adsorbed on the surfaces of the
materials or absorbed within the pores or capillary spaces of
these bulk materials. Any liquids present are typically water
or organic chemicals associated with the bulk materials. The
transfonnative processing disclosed herein forces these gas
and liquid materials from the bulk materials as the interstitial
or porous spaces in the materials are destroyed.
The bulk materials may optionally be prepared for the
initial compaction stage by processes designed to size the
bulk particles to a size acceptable as a feed to the compaction
machinery. Typically, the bulk materials are reduced in size
by processes such as pulverization, crushing, comminution or
the like to a suitable feed size and passed to a collection device
or vessel where they can be stored or fed at a controlled rate
to the compaction machinery.A similar rate control apparatus
may be used to house the bulk materials before they are fed to
an initial comminution device to produce the desired average
feed particle top size. This bulk material may then be subjected
to the first compaction step of the transfonnation processes
of the invention. In a preferred embodiment, the bulk
materials are comminuted to a particle size distribution of a
top size ofat least about 0.006 inch, but less than about 1 inch.
Preferably, the average particle top size ofthe bulk material is
reduced to about 0.04 inch prior to passing the bulk material
to a holding or rate control apparatus and before passing the
bulk material to the first stage compaction step.
The initial process in the transformation of the bulk materials
is compaction of the materials at high pressure. The
compaction preferably removes void spaces within the particles
of the bulk material. The compaction pressure applied
must be sufficient to reduce or destroy at least a portion ofany
void spaces present in the bulk materials. Typically, the bulk
material is compacted under a pressure of at least about 3000
psi. The bulk materials may be compacted at much higher
pressures including as high as 80,000 psi or higher. Preferably,
the compaction pressures are between about 20,000 psi
and about 60,000 psi. More preferably, the compaction pressures
are between about 30,000 psi and about 50,000 psi.
Even more preferably, the compaction pressure applied to the
bulk materials is about 40,000 psi.
7
US 7,913,939 B2
8
gates and embraces a wide variety of operations including
cutting, chopping, grinding, crushing, milling, micronizing
and trituration. For the purposes of the present disclosure,
comminution may be either a single or multistage process by
which material particles are reduced through mechanical
means from random sizes to a desired size required for the
intended purpose. Materials are often comminuted to
improve flow properties and compressibility as the flow properties
and compressibility ofmaterials are influenced significantly
by particle size or surface area ofthe particle.
Preferably, a comminutiontechnique is used that is capable
ofprocessing the compacted products at a feed capacity equal
to, or greater than, the rate at which compacted materials are
being continuously produced from the compactor. If comminuting
machinery incapable ofthis processing speed is used,
a suitable means of collecting the compacted products and
regulating their feed rate into the comminuting machinery
may be used. It should be noted that if counter-rotating rolls
are used to compact the bulk materials as described above, the
rate of compaction can be modified by adjusting the rotation
rate ofthe rolls. Preferably, the type ofcomminution process
used is chosen to produce a product of a particle size distribution
best suited for compaction and transformation.
The compacted bulk materials are comminuted to an average
particle top size ofat least about 0.066 inch. The average
particle top size is preferably less than about 1 inch. The
average particle top size of the bulk material is more preferably
reduced to about 0.04 inch in this comminution step prior
to passing the bulk material onto further processing. The bulk
materials that have been compacted and comminuted in the
processes ofthe present invention have more desirable physical
characteristics than the starting materials including,
greater particle density, lower equilibrium moisture content,
lower water permeability, lower gas permeability, lower
porosity, lower friability index and lower gas content than the
bulk starting materials. In the instance in which low rank
coals are subjected to the transformation processes of the
present invention, in addition to the desirable physical characteristics
listed above, the compacted and comminuted coal
products may also have a higher heating value, lower carbon
dioxide content, lower soluble ash content and lower sulfur
content than the LRC feed material. Additionally, the compacted
and comminuted coal products may be added to water
to form a slurry that has a greater heating value than a similar
slurry formed from the LRC feed material.
Following comminution the comminuted products may be
stored, subject to air or evaporative drying, pneumatically
transferred to a cyclone, bag house, or similar gas/solids
separator for further separation of gasses and vapors, subjected
to additional compaction designed to remove liquids
that may remain in the comminuted products or further processed
for specialized commercial uses. The comminuted
products may also be subject to additional cycles ofcompaction
and comminution. Each succeeding round ofcompaction
and comminution further transforms the bulk materials by
removing more void space from the transformed materials.
In one embodiment, the comminuted products are subjected
to further compaction configured to reduce the presence
ofliquids remaining in the comminuted products. Considerable
liquid may reside on or near the surface of the
comminuted material following a cycle of compaction and
comminution. The use of additional absorptive machinery
further separates this liquid from the solids using high pressures.
This optional absorptive step may be performed using
a second, absorptive compaction step in which the transformed
bulk materials are compacted again using machinery
designed to absorb liquids present in the transformed materials.
This is preformed by applying a compaction pressure of
at least about 3,000 psi. Preferably, the comminuted products
undergoing this absorptive compaction are subjected to compaction
pressures between about 5,000 psi and about 15,000
psi. Preferably, some or all of the liquids residing in the
comminuted products are removed through the use ofporous
compaction machinery that will absorb liquids from the compacted
materials and carry the liquids away from the materials.
For example, another set of counter-rotating rolls com-
10 posed of porous materials that allow liquids residing on the
surface of the feed material to be separated from the solids
may be used in this optional absorptive compaction step. The
porous material of these rolls may contain a sintered metal
that has low permeability and a mean pore size of less than
15 about 2 microns. Alternatively, the porous material of these
pores may be porous ceramic having a low permeability and
a mean pore size ofless than about 2 microns. Liquids present
in the transformed materials are forced from the materials and
driven into the pores ofthe rolls at a rate sufficient to produce
20 a satisfactory product.
FIG. 1 shows a schematic drawing ofa plan view ofa single
preferred absorber roll used in the absorptive counter-rotating
roll assembly that may optionally be applied to the transformed
products to pull liquids away from these materials.
25 FIGS. 2 and 3 show two sectional elevations taken at sections
A-A and B-B ofthe roll of FIG. 1, respectively. Referring to
FIG. 1, the absorber roll unit consists ofa central shaft (2) that
is supported by bearings (3), end pieces (4) and liquid receptors
(5). The receptors (5) are thin, ring-shaped pieces of
30 material such as porous sintered metal or ceramic of a small
pore opening and low permeability to provide a durable item
that can withstand great mechanical stress, yet allow liquid/
solid separation to take place under high pressure. These rings
can be readily placed on the central shaft (2) to provide a
35 unique roll configuration that suits the absorptive application
of these compaction rolls. Damaged rings may therefore be
removed and replaced without overhauling the entire roll
assembly.
Referring to FIGS. 2 and 3, the comminuted feed material
40 (6) is diagrammatically shown entering under mechanical
pressure from the left and exiting the right side of the horizontal
roll assembly. Other orientations of feed entry are
possible without consequence to the liquid/solid separation
phenomena.
45 Companion rolls (7) identical in configuration to the roll
assembly (1) described above are held in proximity to these
rolls along a plane parallel to the axis ofrotation. The rolls are
propelled by a mechanical drive system of standard design to
provide counter rotating motion. Mechanical means exert a
50 specified force on the bearings (3) to maintain the gap
between the rolls, thus providing the pressure to force liquid
held on the comminuted feed material into the receptors.
Liquid contained on the surface of the comminuted feed
material (6) is compacted between the roll assembly (1) and
55 companion roll (7). A portion ofthe liquid is absorbed under
pressure by the receptors (5) as the comminuted feed is
engaged by the rolls. Liquid absorbed by the receptors (5)
migrates from the surface (8) ofthe receptors (5) and, after the
receptors become saturated, flows (9) through numerous
60 weep holes (10) in either ofthe end pieces (4). Liquid remaining
on the surface (8) of the receptors (5) is collected and
removed (11) from the roll assembly (1) by scraper blade
(12). The collected and removed liquid (11) may be collected
in a container (13) for disposal or further processing. In the
65 instance in which LRCs are processed through the transformation
methods ofthe present invention, the liquid recovered
from this absorptive compaction processing will be primarily
US 7,913,939 B2
9
water and the water collected and recovered will be sufficiently
clean for use in further industrial processes without
additional purification. Unlike low-pressure roll devices, reabsorption
ofliquid into the product material is not ofsignificance
because the interstitial, capillary, pores, and other voids
are largely absent due to the previous compaction. Compressed
material (14) having a reduced liquid content exits
this absorptive roll assembly for further processing.
Similar to the compacted products exiting the first, highpressure
compaction step, the compacts exiting this absorptive
compaction step have a pressed fonn that has lower void
space compared to the bulk material applied to this absorptive
compaction step. Particularly, these compacts have a lower
liquid and/or gas content than the bulk materials applied to the
absorptive rollers. These compacts also exit the absorptive
rollers in a compacted ribbon that subsequently breaks into
compacts.
Similar to the post-compaction and comminution processing
procedures described above, transformed materials processed
through this optional absorptive compaction step may
undergo additional processing including storage, air or
evaporative drying, transfer to a bag house for further separation
of gasses or further processed in preparation for specialized
commercial uses. These bulk materials may also be
fed to additional cycles of compaction and comminution to
more extensively remove void space from the materials.
FIG. 4 shows a schematic representation of a preferred
embodiment of these transformation processes applied to
bulk materials, as well as machinery used in these processes.
Referring to FIG. 4, the feed preparation unit (21) accepts a
bulk feed material (24) in a surge bin and feeder (25). A
measured rate ofmaterial is reclaimed from the surge bin and
crushed in comminution machinery (26) to the desired top
size. Comminuted material (27) passes from the feed preparation
unit to the first-stage compaction/crushing unit (22).
In the first-stage compaction/crushing unit (22), comminuted
feed (27) is stored in a surge bin (28) and fed by a
gravimetric feeder (29) at a controlled rate to the primary
double-roll compaction machine (30). The machine produces
primary compacted feed (31) and roll scrapings (32). The
primary compacted product is crushed in comminution
machinery (33). Comminuted product (34) is fed to an
optional secondary double-roll absorption machine (35). The
machine produces first-stage compacted product (36) and
liquids (37) absorbed from the comminuted product (34). The
first-stage compacted product (36) is collected in surge bin
(38) where it is prepared for pneumatic transport. Atmospheric
air (40) is pressurized by fan (39) to engage the
prepared first-stage product to form a mixture (41) suitable
for transport to a baghouse (42).
Fabric filters included in the baghouse (42) separate solids
from vapor. An induced-draft fan (43) draws vapors (44) from
the baghouse and discharges the gas to the atmosphere. Solids
reclaimed by the baghouse (45) may optionally be directed to
bypass further processing (46), or to additional processing
(47) in a second compaction/crushing stage unit (23).
The second-stage compaction/crushing unit (23) is essentially
identical to the first-stage compaction/crushing unit
(22). Similar equipment includes the primary double-roll
compaction machine, comminution machinery, optional secondary
double-roll absorption machine, surge bin, and fan.
Finished product (48) can pass to a final product collection
device or to additional compaction/crushing stages. Additional
rounds of compaction and comminution may be
applied to the products (48) depending on the desired characteristics
of final product. Deployment of the equipment
needed to effect the transformative changes disclosed herein
10
may be carried out rapidly and efficiently through the assembly
and modification of commercially available equipment.
Further processing may also include agglomeration and
preparation for specific commercial uses.
Post-processing procedures may be applied to the transformed
materials. These post-processing procedures are for
the benefit of the mining, transportation or consumer industries.
Any of these industries may benefit from the transformation
ofthe bulk materials by realizing lower costs as esti-
10 mated capital and operating costs may be less than 20% of
bulk materials subjected to alternative thermal drying systems.
Similarly, electricity inputs are estimated to be less than
20% of flue gas, steam, hot oil, and the like, used in some
15 thennal processing options. With respect to the processing of
LRCs using the processing technologies of the present disclosure,
the heat value of the transfonned products may
exceed 10,000 Btu/lb, while the removal ofsome ofthe sulfur,
sodium, oxygen, carbon dioxide and nitrogen emissions from
20 the burning ofthe transformed coal may mitigate the production
of greenhouse gas emissions. Additionally, with respect
to dust control measures, the compaction procedures disclosed
herein will mitigate most windage losses during handling
and transportation of the transfonned materials. Also,
25 the potential for spontaneous combustion resulting from
rehydration is minimized when internal voids are destroyed
by compaction.
Another embodiment is the compacted product resulting
from the application ofthe methods disclosed herein to bulk
30 materials. These compacted materials can have many desirable
physical characteristics for industrial use including a low
equilibrium moisture content (EMQ). Thus, these compacted
materials can have a very low level of rehydration. Typically,
35 the EMQ of these compacted materials is less than about
26%. Preferably, the EMQ of these compacted materials is
less than about 20% and more preferably less than about 15%
and more preferably, less than about 10%. Typically, the
EMQ of the compacted materials is between about 10% and
40 about 25%. For some compacted materials, an EMQ of less
than about 25% represents a significant and advantageous
decrease in the EMQ of the starting bulk material, prior to
processing according to the methodology of the present
invention. Thus, using the techniques described herein, it is
45 possible to reduce the EMQ ofthe starting material by at least
about 5%. Typically, the EMQ ofthe starting bulk material is
reduced by between about 5% to about 70% with successive
rounds of compaction and comminution as disclosed herein.
Preferably, the EMQ ofthe compacted material is reduced by
50 about 10% compared to the EMQ of the non-compacted,
starting materials. More preferably, the EMQ of the compacted
material is reduced by about 20% compared to the
EMQ of the starting (non-compacted) materials, and more
55 preferably, the EMQ ofthe compacted material is reduced by
about 30% compared to the EMQ of the starting materials,
and more preferably, the EMQ of the compacted material is
reduced by about 40% compared to the EMQ of the starting
materials, and more preferably, the EMQ of the compacted
60 material is reduced by about 50% compared to the EMQ of
the starting materials and more preferably, the EMQ of the
compacted material is reduced by about 60% compared to the
EMQ of the starting materials.
Additional objects, advantages, and novel features of this
65 invention will become apparent to those skilled in the art upon
examination ofthe following examples thereof, which are not
intended to be limiting.
US 7,913,939 B2
11
EXAMPLES
12
TABLE 1
Example 1
Eguilibrium Moisture Contents of Raw Feed and Compacted Products
Lignite
Subbituminous Coal (Nortb
(Powder River Basin) Dakota)
27.0% 32.4%
16.4% 26.2%
15.7% 23.6%
14.3% 21.9%
12.9% 20.0%
11.9% 18.6%
Material
Unprocessed Feed
1sf Stage Compaction/Comminution
Product
2nd-Stage Compaction/Comminution
Product
3rd-Stage Compaction/Comminution
Product
4th-Stage Compaction/Comminution
Product
5th-Stage Compaction/Comminution
Product
These data show that compaction and comminution of
LRC bulk materials using the processes ofthe present invention
can significantly reduce the EQM of the bulk materials
and that, with each successive round ofcompaction and comminution,
the EQM is reduced. Additionally, these data demonstrate
the ability to reduce the EQM of bulk materials by
20-40% after only one round of compaction and comminution,
while theEQMcanbe loweredby 40-60%, or more, with
subsequent rounds of compaction and comminution.
The foregoing description ofthe 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 ofthe relevant art, are within the scope
of the present invention. The embodiment described hereinabove
is further intended to explain the best mode known for
35 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 ofthe present invention. It is intended that the
appended claims be construed to include alternative embodi-
40 ments to the extent permitted by the prior art.
What is claimed is:
1. A method of removing void spaces present in a carbonaceous
material comprising:
comminuting a carbonaceous material to form a crushed
material;
compacting the crushed material in a counter-rotating roll
compaction machine to produce a compacted material;
comminuting the compacted material to form a compacted
comminuted material;
compacting the compacted comminuted material in porous
counter-rotating rolls to produce a granular product;
pneumatically-transporting the granular product to a gas/
solids separator using pressurized air; and,
separating vapors from the granular product to form a dried
granular product.
2. The method of claim 1, further comprising:
compacting the dried granular product in a counter-rotating
roll compaction machine to produce a dried compacted
material;
comminuting the dried compacted material to form a dried
comminuted material;
compacting the dried comminuted material in porous
counter-rotating rolls to produce a final product.
3. The method ofclaim 1, wherein the carbonaceous mate65
rial is a coal selected from the group consisting ofbituminous
coal, peat, low-rank coal, brown coal, lignite and subbituminous
coal.
Example 2
Various LRC samples were processed using the procedures
and equipment diagramed in FIG. 1 and described above. The
effects ofthese mechanical transformation processes and the 45
quality of the finished compacted products were evaluated.
To evaluate the transformative effects and the quality ofthe
finished products, the equilibrium moisture content (EQM) of
LRC feeds and products was measured. The EQM is defined
by the American Society of Testing and Materials (ASTM) 50
procedureASTM D-14l2. The EQM is the moisture content
held by coal stored at a prescribed temperature of 30° C.
under an atmosphere maintained at between 96% and 97%
relative humidity. Under these conditions, moisture is not
visible on the surface of the coal, but is held in the capillary, 55
pores, or other voids. Coals with low EQM contain less capillary,
pores, or other void volume to hold water. These coals
have typically more useful thermal energy than coals with
higher EQM, and are subsequently more valuable as feedstock
for energy generation processes. Table 1 shows the 60
results ofEQM testing conducted on samples ofsubbituminous
coal supplied from the Power River Basin, Wyo., USA
and lignite from North Dakota, USA, prior to, and after five
successive stages of compaction/comminution. In each cycle
ofcompaction/comminution, a compaction pressure ofabout
30,000 psi was applied at ambient temperature for less than 1
second.
A detailed study oftwo bulk materials (high-moisture lignite
from SouthAustralia and brown coal from Victoria, Australia)
was undertaken to assess the effects of particle size,
washing and leaching, additives, agglomeration, briquetting,
slurrying, rehydration, autoclaving, and the application of 10
thermal energy and pressure, as effective methods of transforming
or beneficiating low rank coal (LRC) to provide a
more useful, cost effective, clean fuel. The test program
revealed comminution to a specific particle size range and 15
compaction, configured in the continuous mode ofthe present
invention to be the most beneficial factors in the mechanical
transformation of LRC into a high quality fuel.
Published reports (Anagnostolpoulos, A., Compressibility
Behaviour ofSoft Lignite, J. Geotechnical Engineering 108 20
(12): (1982); and Durie, R. Science ofVictorian Brown Coal:
Structure, Properties and Consequences of Utilisation,
CSIRO, Sydney, Australia (1991)) dealing with similar LRCs
showed that some moisture can be removed when low pressures
in the range of 1400 psi to 2300 psi are applied to the 25
material over several days at ambient temperatures. Similarly,
low pressures ofabout 500 psi have been used in combination
with thermal processing in several prototype beneficiation
systems (McIntosh, M. Pre-drying ofHigh Moisture Content 30
Australian Brown Coalfor Power Generation, 22nd Annual
International Coal reparation Conference, Lexington, Ky.
(2005); and Van Zyl, R. History and Description ofthe KFx
Pre-Combustion Coal Process, 22nd Annual International
Coal Preparation Conference, Lexington, Ky. (2005)).
The present inventors' research shows that low-pressure
compaction does not permanently transform the physical
characteristics of these bulk materials.
US 7,913,939 B2
13 14
25
15
30
20
coal, brown coal, lignite, subbituminous coal, coke and
combinations thereof, to form a crushed material of
reduced particle size;
compacting the crushed material in a counter-rotating roll
compaction machine at a compressive force between
about 20,000 psi and about 40,000 psi to produce a
compact in which internal void spaces have been
destroyed to release gas and liquids to the surface ofthe
compact; and,
separating vapors from the compact in a gas/solids separator
to form a dried carbonaceous product.
11. A method ofremoving void spaces and vapors present
in carbonaceous materials comprising:
comminuting a carbonaceous material selected from the
group consisting of bituminous coal, peat, low-rank
coal, brown coal, lignite, subbituminous coal, coke and
combinations thereof, to form a crushed material of
reduced particle size;
compacting the crushed material in a counter-rotating roll
compaction machine at a compressive force between
about 20,000 psi and about 40,000 psi to produce a
compact in which internal void spaces have been
destroyed to release gas and liquids to the surface ofthe
compact;
transferring the compact into a gas/solids separator; and,
separating vapors from the compact in the gas/solids separator
to form a dried carbonaceous product.
12. The method of anyone of claims 8-11, further comprising:
compacting the dried carbonaceous product in a counterrotating
roll compaction machine to produce a dried
compact.
13. A method ofremoving void spaces and vapors present
in carbonaceous materials comprising:
comminuting a carbonaceous material to form a crushed
material of reduced particle size;
compacting the crushed material in a counter-rotating roll
compaction machine to produce a compact having
reduced interstitial voids and gases; and,
separating vapors from the compact in a gas/solids separator
to form a dried carbonaceous product.
14. The method of claims 13, further comprising:
compacting the dried carbonaceous product in a counterrotating
roll compaction machine to produce a dried
compact.
15. The method of claim 13, wherein the carbonaceous
material is selected from the group consisting of bituminous
coal, peat, low-rank coal, brown coal, lignite, subbituminous
coal, coke, and combinations thereof.
* * * * *
4. The method ofclaim 1, wherein the carbonaceous material
is selected from the group consisting of bituminous coal,
peat, low-rank coal, brown coal, lignite, subbituminous coal,
coke, and combinations thereof.
5.A method ofremoving void spaces and vapors present in
carbonaceous materials comprising:
comminuting a carbonaceous material to form a crushed
material ofreduced particle size;
compacting the crushed material in a counter-rotating roll
compaction machine to produce a compact having 10
reduced interstitial voids and gases;
transferring the compact into a gas/solids separator; and,
separating vapors from the compact in the gas/solids separator
to form a dried carbonaceous product.
6. The method ofclaim 5, wherein the carbonaceous material
is selected from the group consisting of bituminous coal,
peat, low-rank coal, brown coal, lignite, subbituminous coal,
coke, and combinations thereof.
7. The method of claim 5, further comprising:
compacting the dried carbonaceous product in a counterrotating
roll compaction machine to produce a dried
compact.
8.A method ofremoving void spaces and vapors present in
carbonaceous materials comprising:
comminuting a carbonaceous material selected from the
group consisting of bituminous coal, peat, low-rank
coal, brown coal, lignite, subbituminous coal, coke and
combinations thereof, to form a crushed material of
reduced particle size;
compacting the crushed material in a counter-rotating roll
compaction machine to produce a compact; and,
separating vapors from the compact in a gas/solids separator
to form a dried carbonaceous product.
9. A method ofremoving void spaces and vapors present in 35
carbonaceous materials comprising:
comminuting a carbonaceous material to form a crushed
material ofreduced particle size;
compacting the crushed material in a counter-rotating roll
compaction machine at a compressive force between 40
about 20,000 psi and about 40,000 psi to produce a
compact in which internal void spaces have been
destroyed to release gas and liquids to the surface ofthe
compact; and,
separating vapors from the compact in a gas/solids separa- 45
tor to form a dried carbonaceous product.
10. A method of removing void spaces and vapors present
in carbonaceous materials comprising:
comminuting a carbonaceous material selected from the
group consisting of bituminous coal, peat, low-rank