7,913,939 Method to transform bulk material

Patent Number/Link:

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

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

::,:

f'- 23

i,,,,,,,,,

:,,,,

$ ,

4D~9 i

)' , ______________ ~~ __1 l

,- --1- ------ -- -,- ---,

i,,,:i,,,,,f

-------- -I- ----- ---, -------- - --+

221,,,,,,i,,:,

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

Figure 1

f.-<f-- 13

Figure 2

Figure 3

12~

u.s. Patent Mar. 29,2011 Sheet 2 of2 US 7,913,939 B2

IIIIII

!'-- 23

----,

IIIIII 42

--27

29-

r-- 24 21 \

r--+----------~----l

I11IIII

III

IIII

~-------- ---------~------------

III

22~

35----.100 00 ....I--L:....,....:::~

-----I~)

Figure 4

US 7,913,939 B2

METHOD TO TRANSFORM BULK

MATERIAL

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.

FIG. 3 shows an elevation at section B-B ofthe roll ofFIG.

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.

US 7,913,939 B2

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

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

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

EXAMPLES

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

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