Note: Descriptions are shown in the official language in which they were submitted.
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Desc_ ption
PRODUCTIOM OF SOLID FUEL SHAPES FROM COAL FINES
Technical Field
The present invention relates to an inexpen3ive solid
5 fuPl produced from waste coal dust or fines and a
concen~rated liquor by-product of the sulfite paper making
process, and to a method of manufacturing such solid fuel.
Back~round _
The patent li-t~rature contains a large number of
10patents relating to various methods of casting mixtures oE
coal particles and various binder materials into solid fuel
shapeR. With but one exception, a common denominator of
these prior patents is the belief that it was not possible
to use a sulfite liquor by-product of the sulEite paper
15 making process alone as a binder.
U.S. Patent 1,678,387, granted July 24, 1928, to Robert
M. Hale, suggests obtaining a good bond by using coal fine~
which have been oil-coated before being mixed with th~
lignin material. U.S. Patent No. 585,001, granted June 22,
20 1897, to Nicoll MacDonald, discloses adding lirne water to a
mixture which include~ coal particles and "pulped paper",
coal-tar and crude petroleum. U.S. Patent No. 782,991,
granted February 21, 1905, to Sarnuel P. Sadtler, discloses
adding sodium carbonate to a mixture of "fine coke-powder"
25 and "concentrated waste liquor of the sulPite wood-pulp
process". U.S. Patent No. 969,504, granted September 6,
1910, to Ernst Trainer, discloses the addition of a
chromium compound to obtain a good bond. U.S. Patent No.
1,084,479, granted January 13, 1914, to Max Platsch,
30 disclo~e~ the addition oE sulfuric acid. U.S. Patent No.
1,507,676, granted September 9, 1924, to Theodore Nagel,
discloses the addi.tion of phosphoric acid. V.S. Patent No.
1,576,248, gran-ted March 9, 1929 to Jacob S. Robeson,
discloses adding "crude rnolasses" and "wood tar". U.S.
Patent No. 1,596,239~ gran-ted August 17, 1926, to John P.
Delzeit, discloses adding "sulfur" and "sulfuric acid".
U.S. Patent ~o. 1,615,463, granted January 25, 1927, -to
Michael E'. Maginnis, discloses adding "starch", "glue" and
"alum". U.S. Patent No. 1,618,24g, granted February 22,
1927, to Samuel F. Walton, discloses adding a "cellulose
solution". It is stated in this patent that the cellulose
10 apparently forms a physical union with the sulite liquor.
It is said that the cellulose protects the briquettes from
the effects of water or moisture until they are generally
carbonized by combustion in use. The patentee states that
"unless carbonized or otherwise chemically treated, sul~ite
15 liquor by itself would be unsatisfac~ory as a binder,
because it i8 hygroscopic and absorbs moi~ture; so that
afte~ mere drawing briquette bonded with ~ulfite liquor
alone would absorb moisture from the atmosphere and
disintegrate". The patentee further states "cellulose used
20 alone as a binder, on the other hand, would disintegrate in
burning".
U.S. Patent No. 1,623t764, granted April 5, 1927, to
Srinivas R. Wagel, discloses adding "clay and asphalt".
U.S. Patent No. 1,752,838, granted April 1, 1930, to
25 Francis M. Crossman, discloses adding "raw starch or any
farinaceous material containing starch and gluten", and a
small percentage of "sodium nitrate". U.S. Patent No.
1,908,862, granted May 16, 1933, to Charles H. Reese,
discloses adding "lirne" and "a coagulant such as gellatin
30 or glue". U.S. Patent No. 2,567,136, gran-ted September 4,
1951, to Antoine Vloeberghs, discloses the addition of a
"phenolormaldehycle resin". U.S. Patent No. ~329,042,
granted August 21, 1906, to Bernhard Wagner, teaches
manufacturing briquettes by (1) heating "anthracite" up to
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about 140 degrees centigrade; (2) heating waste lyes from
cellulose-factories up to about 60 degrees centigrade; ~3)
mixing the two substances together in a mixing apparatus
while maintaining a -temperature of the mi~ture of about 100
5 degrees centigrade; and (4) -feeding the mixture into a
press at about 100 degrees centigrade. The patentee states
that for the purpose of maintaining the mass at the pro,per
degree of temperature in a mixing apparatus, and of
enabling anthracite or other material used and the binding
10 medium to be intimately mingled as possible, super heated
steam may advantageously be conducted directly into, the
mixture.
The single patent which discloses using waste sulfite
liquor alone is U.S. Patent No. 1,667,304, granted April
15 24, 1928, to Ernst W. Bowen. Bowen states that he is able
to obtain proper bonding by first separating the fine dust
or flour from the granular portion of the anthracite or
other coal. The granular portion of the coal is mixed with
a waste sulphite liquor obtained from wood~pulp mills, and
20 then the dust or flour is added to the mixture "in definite
proportions". The patentee suggests separating the flour
from the granular parts by a two stage screening process.
The yranular coal is dried and is then mixed with sulphite
liquor at about 150 degreeq Fahrenheit in a suitable
25 machinP which ensures a thorough distribution of the liquor
throughout the granular material. This mixture consists of
86 percent by weight of granular to 9 percent by weight of
sulphite liquor. A~ter these constituants have been
thoroughly mixed, approximately 5 percent dust or flour is
30 added and the mixing operation i9 repeated until the mass
becomes truly pla~tic. The plastic mass is molded into
briquetkes which are baked at a tempera-ture of abou~ 630
degrees Fahrenheit for approximately twenty minutes and are
then cooled.
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U.S. Patent No. 3,684,465, granted August 15, 1972, to
Harry L. Hsu, discloses the use of a~monium lignin
sulfonate liquor as a binder material in the manufacture of
fuel briquets. SpeciEically, this patent discloses that
the amount of binder employed should be be-tween about 3 and
about 10 parts by weight per 100 parts of the carbon
aggregate employed. It also sta-tes that in all cases the
total amount o water employed in any given mixture should
be bet~een about 5.0 and about 8.0 parts per weight per 100
10 parts of the carbon aggregate and the parts oE water used
is inclusive of the water or moisture contained in the
carbon aggregate materials and in the bindex. The mixture
is formed into the desired shape in a roll briquetting
operation employing a pressure force of at least 1.0 metric
15 ton per centimeter of face con-tact.
The above described patents, and the additional patents
listed below, all should be carefully considered for the
purpose of putting the present invention into proper
perspective: U.S. Patent No. 478,229, granted July 5,
1892, to Jerome W. Frank; U.S. Patent No. 257,985, granted
May 16, 1882, to William C. Siffken U.S. Patent No.
829,072, granted August 21, 1906, to Henry Hill; U.S.
Patent No. 1,780,205, grantsd November 4, 1930r to Henry F.
Maurel; U.S. Patent No. 3,297,419, granted January 10,
1967, to Edward E. Eyre, Jr.; U.S. Patent No. 3,635,684,
granted January 18, 1972, to Donald E. Seymour; U.S. Patent
No. 3,829,297, granted August 13, 1974, to Chester C.
Crawford; U.S. Patent No. 3,883,317, granted May 13, 1975,
to Fuhad A. Neme; U.S. Patent No. 4,152,119, granted May 1,
1979, to Helmut W. Schulz; [J.S. Patent No. 4,230,459,
granted october 28, 1980, to Jean R. Mareau, Martin P.
Pelletier and Gerard B. Tremblay; and U.S. Patent No.
4,243,393, granted January 6, 1981, to Mi]es W. Christian.
~escription of the Inventlon
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In accordance with the present invention, waste coal
fines are combined with ammonium lignin sulfonate liquor,
or an equi~alent by-product oE a paper manufacturing
process, -to produce relatively large size fuel shapes, viz.
logs or bricks.
In accordance with an aspect of the invention,
substantially dry coal fines are combined with only enough
concentrated liquor to wet surface portions oE the fines.
The coal fines, wekted in this manner, are placed into
10 molds and are tightly compressed together to form the fuel
shapes. The fuel shapes are then removed from the molds
and are dried.
According to an aspect of the invention, the liquor is
thinned by heating prior to its being combined with the
15 coal fines. Thinning in this manner facilitates an even
distribution of the liquor throughout -the coal fines.
In accordance with another aspect of the invention,
coal fines which when obtained have a moisture content of
more -than 5~ by weight are dried before combining them with
20 the liquor un-til the ~oisture in them is no more than about
5% by weight. Preferably, the coal fines are dried by
fluLdizing them with heated air. The heated air may be air
obtained from a dryer used for drying the compressed fuel
shapes~
Preferably, the by-product liquor is ammonium lignin
sulfate liquor. Preferably also, a liquor is used which
includes between 40-60~ solids by weight~
In accoxdance with another aspect of the invention, the
by-product liquor is used in a quantity and concentration
30 such that the ratio of wet coal fines to liquor solids i5
between 13:1 and 20:L by weight, and the total moisture i~
between 3~ and 7% by weight.
PreEerably, the by-product liquor is heated to a
temperature oE about 180 degrees F. to about 220 degrees F'.
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prior to combining it with coal fines.
In accordance with an aspect of the invention, the
liquor wetted coal fines are placed into log forming
cavities and are compressed by hydraulically moving a
piston in through one end of the cavity, against the liquor
wetted coal fines, while closing the opposite end of the
cavity.
In accordance with yet another aspect of the invention,
the shapes are removed from their molds and are dried. Air
drying will work. However, the preferred practice is to
place the shapes into ovens and heat them in such ovens to
no more than about 200 degrees F. until they are
sufficiently hardened so that they will hold together
during normal handling and during the burning process.
Normally, this requries heat for about 2 to about 6
hours.
In accordance with another aspect of the invention,
after drying the soild fuel shapes are coated with a wax
substance, e.g. slack wax, parafin etc.
Additional objects, features and advantages of the
invention will be appareht form the following description
of a preferred embodiment of the invention.
Brief Description o fhte Drawing Figures
Referring to the drawing:
Fig. 1 is a flow diagram of an embidoment of the
process of the invention;
Fig. 2 is a side elevational view of a first embodiment
of a fuel log forming machine;
Fig. 3 is a top paln view of the machine shown by Fig.
2;
Fig. 4 is a pictorial view of a second machine for
casting cylindrical fuel shapes or logs;
Fig. 5 is a cross-sectional view taken substantially
along line 5-5 of Fig. 4;
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Fig. 6 is a longitudianl sectional view taken through
the feed station;
Fig. 7 is a longitudinal sectional view taken through
the compact station; andact station; and
Fig. 8 is a longitudinal sectional view taken through
the eject section.
Description of the Preferred Embodiment
Referring to Fig. 1, dry coal fines, one quarter minus,
and a suitable liquor by-product of a paper making process
are combined together in such a manner that the liquor is
substantially evenly disbursed or distributed amongst the
coal fines.
Preferably, mine run coal fines are used because they
are a waste product. At the present time ther is an
abundant supply of one quarter minus mine run coal fines.
However, under some circumstances, it might be desirable to
crush larger coal particles to produce the coal fines.
The coal fines may come from the mines or storage in a
dry enough condition that drying is not necessary before
combining them with the by-product liquor. This would be
particularly true whne the coal fines are obtained from
mining operations conducted during the warm months of the
year. However, when the coal fines are obtained with the
mositure content greater than about 5% by weight, it is
necessary to dry them before use. Preferably, the coal
fines are dried by fluidizing them with heated air. Heated
air may be obtained from a dryer or oven used to dry the
fuel shapes. For example, a fan or pump may be used to
remove air from the interior of the dryer to the inlet of a
fluidized bed through which the coal particles must pass
before being combined with the by-product liquor.
In accordance with the invention, a concentrated liquor
is used so that it will add very little moisture which must
later be removed. The concentrated liquor is heated,
preferably to a temperature of about 180 degrees F. to
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about 220 degrees F., beEore being combined with -the coal
fines. When cold, the concentrated liquor has the
consistency of a thick molasses. The heating thins the
liquor to a water like consistency, so that it can be
substantially uniformly disbursed throughout the coal
fines.
By-product liquor is used in only an amount sufficient
to wet the coal finesO In other words, it all becomes a
thin coating on surface portions of the coal fines and does
lO not exist in a liquid form, droplet or otherwise, between
the coal fines.
Preferably, the by-product liquor used includes between
40-60~ solids by weight. By way of example, the by-product
liquor may be the liquid form of an ammonium lignin
15 sulfonate liquor which is sold by The Scott Paper Company,
a Pennsylvania Corporation, under the trademark TREX ~ LTA.
This material is a liquid form of ammonium lignin
sulfonate and wood sugars. It is manufactured by the
sulfite paper making process as a co-product with wood
20 pulp. Prior to digestion, wood consists of bundles of
cellulose ibers cemented together by lignin and
hemicellulose. In the sulfite pulping process, ammonium
lignin sulfonates and wood pulp are produced simultaneously
by a series of chemical reactions when wood chips are
cooked under controlled conditions of heat and pressure in
an aqueous solution of ammonium bisulfite and sulphur
dioxide. This is accomplished in a tall cylindrical
pressure vessel known as a "digester". The ammonium
bisulfite and sulphur dioxide react with lignin to form
30 water soluable lignin su]phona-te~ The hemicelluloses
(carbohydrates) are broken down into water soluable 5-
carbon and 6- carbon reducing sugars, such as
glucose, glactose, mannose, ylose, and arabinose. Simple
filtration separa-tes the wood pulp, which is to be made
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into paper, from the ]ignin sulfonates and other
components, which are available as chemical raw materials.
This coffee colored liquid or liquor is collected as a
solution of about 10~ solids, and is then concentrated by
the removal of water to the 50-55~ solids level in an all
stainless evaporator. This concentrate is sold by Scott as
TREX ~ LTA and is a mixture of ammonium liynin sulphonates,
wood sugars and other chemicals dissolved in water.
Additional information with respect to TREX ~ LTA is
10 contained in a Scott Paper Company brochure, entitled TREX
lignin sulfonates. The contents of this brochure are
hereby expressly incorporated by reference into this
application. A copy of the brochure is in the patent file.
Fuel shapes constructed in accordance with the present
15 invention typically fall within the size range oE about 40
to about 300 cubic inches. By way of typical and therefore
nonlimitive example, cylindrical logs may be manufactured
which measure about 3-5 inches in diameter and about 6-15
inches in length. A preferre~ size of log measures about 4
20 inches in diameter by about 12 inches in length.
Rectangular bricks, such as shown in Fig. 1 may measure
about 2-3 inches in depth, by about 2-6 inches in width, by
about 6-15 inches in length.
Whether the shapes be bricks or logs, in either case
25 the liquor wetted coal fines are introduced into a mold and
are subjected while in -the mold to a pressure of at least
2000 psi. In a typical log manufacturing process, the
pressure applied is preferably about 3000 psi, for a high
quality product.
The liquor wetted coal fines are much like damp beach
sand when they are placed in the mold. For example, a
common cup could be hand packed with the liquor wetted coal
fine~ and then turned upside down and emptied onto a
surface and the coal fines would assume a shape
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corresponding to the inside shape of the cup, in the same
manner as if damp beach sand were used.
When the pressurized shapes are removed from the molds,
they are relatively firm. The pressure compacting causes
the liquor -to bind the coal fines together. Af-ter they
havë been dried, the fuel shapes have the ability to hold
toyether during shipping and other handling, and during the
burning process.
The fuel shapes may be air dried. However, in
10 preferred practice, drying is excellerated by placing the
shapes within an oven and heating them to about 180 degrees
F. to about 220 degrees F., for about 2 to about 6 hours.
The oven temperature and heating time are so chosen that
the fuel shape will solidify withou-t excessive swelling or
15 distortion. A very good product was obtained by heating
the shapes in an oven at a temperature of about 200 degrees
F. for about 2 hours. The particular shapes were in log
forrn and they measured about 4 inches in diameter by about
12 inches in length.
Preferably, the fuel shape is dipped or spray coated
with a suitable wax substance, such as "slack wax" or
parafin. j
"Slack wax" sometimes referred to as "grease wax", is a
by-product of the petroleum refining processO
The wax coating has two distinct advantages. It seals
the fuel shape, making it relatively clean to handle. That
is, it prevents surface coal fines from coming off in the
form of dust. Secondly, the wax coating helps the fuel
shape become ignited, particularly if parafin is used.
A fuel log manufacturing operation will now be
describecl, wi~h reference to Figs. 2-4.
The apparatus shown in Figs. 2 and 3 compxises a main
frame 10 which mounts a double acting hydraulic linear
motor 12. I,inear motor l2 comprises a cylinder 14, having
a fluid line ]6, 18 at each of it's ends. In usual
fashion, the lines, 16, 18 convey hydraulic fluid into and
outfrom chambers formed on opposite sides of a pis-ton head
tnot shown). A piston rod 20 extends outwardly from one
end of the cylinder l4 and includes a pressure ram 22 at
it's outer end.
A cylindrical mold cavity is formed in line with the
piston rod 20. An upper sidewall opening 27 in a firs-t end
portion of the cylindrical mold cavity 23 is in coal fine
receiving communication with a hopper 26. The liquor
wetted coal -Eines are introduced into the hopper 26 and are
fed by the hopper 26 into the mold cavity 24. Preferably,
a shaft 28 carrying a plurality of paddles 30 is mounted
Eor rotation within the hopper 26, and is rotated by a
motor 3~, mounted on the frame lO outside of the hopper 26.
The paddles 30 keep the liquor wetted coal fines mass
loose, allowing it to drop by gravity into the top opening
27 of the mold cavity 24.
The second end o the mold cavity 24 is opened and
closed by means o retraction and extension of a second
linear hydraulic motor 34. In the illustrated embodiment,
motor 34 is set at an incline. Motor 34 concludes a
cylinder 36, shown anchored to a frame member 38, and a
piston 40. Piston 40 includes a piston head 42 at it's
inner end and a ~losure pad 44 at it's outer end. When the
piston 40 is extended, as shown in Fig. 3, the closure pad
44 is moved into a position whereat it closes an end
opening provided in the mold cavity 24. Retraction of the
piston 40 moves the closure pad 44 both away from the end
opening and above the level of the end opening.
In opera-tion, after a sufficient amount of the liquor
wetted coal Eines mass has been allowed to enter the mold
cavity, the piston rod 20 is extended by operation of
c~linder 14 while closure pad 44 is held against the
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opposite end of the mold cavity 24, by operation of linear
motor 24. The pressure pad 22 is hydraulically moved
against the liquor wetted coal fines within cavity 24, to
in that manner, compress them tightly together. In the
illustrated embodiment, the mold cavity 24 measures about 4
inches in diameter. The applied pressure was about 30,000
psi. When this pressure level was reached, the length of
the pressurized mass within the cavity 24 was about 12
inches.
Following sufficient pressurization, the pressure is
removed, piston 40 is retracted until the closure pad 44 is
above the elevation of the end opening, and the piston 20
is again extended, this time for the purpose of moving the
compressed fuel shape endwise outfrom the mold cavity 24.
A conveyor (not shown) may be positioned at the outlet of
the mold cavity, for conveying the fuel shapes onto the
drying station.
A sliding gate (not shown) may be mounted on an upper
portion of the mold cavity, to be adjustably movable
endwise for the purpose of adjusting the length of the
opening 27.
Figs. 4-8 relate to a second embodiment of a mechanized
mold for casting cylindrical fuel logs. This embodiment is
characterized by a rotating turret 49, mounted for rotation
about an axis 50. Turret 48 comprises three chambers 52,
54, 56.
A hopper fed screw feed mechanism 58 is provided for
delivered liquor wetted coal fines into the chambers 52,
54, 56, one at a time. An end wall 60 provides a reaction
surface at the second end of the particular chamber 52, 54,
56 which is in alignment with the feed mechanism 58. When
a given cavity 52, 54, 56 is full, the turret 48 is rotated
to palce such cavity in line with the pressure pad 58 of a
compaction device. The compaction device is a double
acting linear hydraulic motor 60, having a pair of fluid
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1ines 62, 64 leading to opposite ends o:E a cylinder chamber
from a sw.itching valve 66. When fluid is introduceq into
line 62 and removed from line 64, the piston 68 is extended
and the pad 56 is moved into pressure applying contact with
the liquor wetted coal fines wit'hin the mold cavity. At
this s-tation, the second end of the mold cavity is also
closed by the wall 60.
Following sufEicient compression, -the switching valve
66 is reversed, directing fluid into line 64 and outfrom
line 62, resulting in a retraction of the pressure pad 58
outfrom the mold cavity. ~he turre-t is once again rotated,
the mold cavity into alignment with both an outlet opening
70 in the wall 60 and the head 72 of an ejector piston 74.
Switching valve 76 is operated to cause the flow of
'hydraulic fluid into line 78 and the flow of hydraulic
fluid outfrom line 80. The extending pis-ton 74 moves
against the end of the compressed fuel log L and moves it
outfrom the mold cavity, through the opening 70 in wall 60~
Following such removal, the position of valve 76 is
reversed. This causes the delivery of hydraulic fluid into
line 80 and outfrom line 78, and a retraction of the piston
74. The log L is then moved onto the drying station.
As should be evident, the provi~ion of three mold
cavities 52, 54, 56, enables one of the mold cavities to be
at each of the three operational station3 at each cycle of
the operation. That is, while liquor wetted coal fines are
being introduced into one of the cavities, the piston 68 is
being extended to compress the liquor wetted coal fines in
a second cavity and the pi.qton 74 is being extended to
eject a log L outErom the third cavity.
Rectangular shape ~ue'L pieces were successively
manufactured in a conventional brick forming machine of the
type used Eor casting structural bricks. The bricXs were
cast to include through openings 82, provided for the
purpo3e of enllancing gasification during the burning
proces3.
