[0001] This invention relates to the beneficiation of coal and more particularly to an improved
process for the beneficiation of coal and separation of impurities therefrom and the
formation of stable beneficiated coal mixtures, such as coal oil. mixtures.
[0002] Known resources of coal and other solid carbonaceous fuel materials in the world
are far greater than the known resources of petroleum and natural gas combined. Despite
this enormous abundance of coal and related solid carbonaceous materials, reliance
on these resources, particularly coal, as primary sources of energy, has been for
the most part discouraged. The availability of cheaper, cleaner burning, more easily
retrievable and transportable fuels, such as petroleum and natural gas, has in the
past, cast coal to a largely supporting role in the energy field.
[0003] Current world events, however, have forced a new awareness of global energy requirements
and of the availability of those resources which will adequately meet these needs.
The realization that reserves of petroleum and natural gas are being rapidly depleted
in conjunction with skyrocketing petroleum and natural gas prices and the unrest in
the regions of the world which contain the largest quantities of these resources,
has sparked a new interest in the utilization of solid carbonaceous materials, particularly
coal, as primary energy sources.
[0004] As a result, enormous efforts are being extended to make coal and related solid carbonaceous
materials equivalent or better sources of energy, than petroleum or natural gas. In
the case of coal, for example, much of this effort is directed to overcoming the environmental
problems associated with its production, transportation and combustion. For example,
health and safety hazards associated with coal mining have been significantly reduced
with the onset of new legislation governing coal mining. Furthermore, numerous techniques
have been explored and developed to make coal cleaner burning, more suitable for burning
and more readily transportable.
[0005] Gasification and liquefaction of coal are two such known techniques. Detailed descriptions
of various coal gasifaction and liquefaction processes may be found, for example,
in the Encyclopedia of Chemical Technology, Kirk-Othmer, Third Edition (1980) Volumne
11, pages 410-422 and 449-473. Typically, these techniques, however, require high
energy input, as well as the utilization of high temperature and high pressure equipment,
thereby reducing their widespread feasibility and value.
[0006] Processes to make coal more readily liquefiable have also been developed. One such
process is disclosed in U.S. Patent No. 4,033,852 (Horowitz, et al.). This process
involves chemically modifying a portion of the surface of the coal in a solvent media,
the effect of which renders the coal more readily liquefiable in a solvent than natural
forms of coal, thereby permitting recovery of a liquefiable viscous product by extraction.
[0007] In addition to gasification and liquefaction, other methods for converting coal'to
more convenient forms for burning and transporting are also known. For example, the
preparation of coal-oil and coal-aqueous mixtures are described in the literature.
Such liquid coal mixtures offer considerable advantages. In addition to being more
readily transportable than dry solid coal, they are more easily storable, and less
subject to the risks of explosion by spontaneous ignition. Moreover, providing coal
in a fluid form makes it feasible for burning in conventional apparatus used for burning
fuel oil. Such a capability can greatly facilitate the transition from fuel oil to
coal as a primary energy source. Typical coal-oil and coal-aqueous mixtures and their
preparation are disclosed in U.S. Patent No. 3,762,887, U.S. Patent No. 3,617,095,
U.S. Patent No. 4,217,109, U.S. Patent No. 4,101,293 and British Patent No. 1,523,193.
[0008] Regardless, however, of the form in which the coal is ultimately employed, the coal
or coal combustion products must be cleaned because they contain substantial amounts
of sulfur, nitrogen compounds and mineral matter, including significant quantities
of metal impurities. During combustion these materials enter the environment as sulfur
dioxides, nitrogen oxides and compounds of metal impurities. If coal is to be accepted
as a primary energy source, it must be cleaned to prevent pollution of the environment
either by cleaning the combustion products of the coal or the coal prior to burning.
[0009] Accordingly, physical as well as chemical coal cleaning (beneficiation) processes
have been explored. In general, physical coal cleaning processes involve pulverizing
the coal to release the impurities, wherein the fineness of the coal generally governs
the degree to which.the impurities are released. However, because the costs of preparing
the coal rise exponentially with the amount of fines to be treated, there is an economic
optimum in size reduction. Moreover, grinding coal even to extremely fine sizes may
not be effective in removing all the impurities. Based on the physical properties
that effect the separation of the coal from the impurities, physical coal cleaning
methods are generally divided into four categories: gravity, flotation, magnetic and
electrical methods. In contrast to physical coal cleaning, chemical coal cleaning
techniques are in a very early stage of development. Known chemical coal cleaning
techniques include, for example, oxidative desulfurization of coal (sulfur is converted
to a water-soluble form by air oxidation), ferric salt leaching (oxidation of pyritic
sulfur with ferric sulfate), and hydrogen peroxide-sulfuric acid leaching. Other methods
are also disclosed in the above-noted reference to the Encyclopedia of Chemical Technology,
Volume 6, pages 314-322.
[0010] While it is obvious from the foregoing that enormous efforts have been made to make
coal a more utilizable.source of energy, further work and improvements are still necessary
and desirable before coal, coal mixtures and other solid carbonaceous fuel sources
are accepted on a wide scale as primary sources of energy.
[0011] Thus, the present invention relates to a process which comprises contacting coal
in an aqueous medium with a surface treating mixture comprising a polymerizable monomer,
a polymerization catalyst and a liquid organic carrier, thereby providing a hydrophobic
and oleophilic coal product adapted to the removal of further ash and sulfur by water
separation techniques. The resultant product is highly suitable for the formation
of beneficiated coal slurries and/or cleaned particulate coal.
[0012] Moreover, in a further embodiment of the present invention an improved process for
beneficiating coal is provided which comprises chemically surface treating coal in
an aqueous medium to render said coal hydrophobic and oleophilic, thereafter separating
the hydrophobic and oleophilic coal phase from the ash containing water phase and
recovering the hydrophobic and oleophilic coal phase, the particular improvement comprisinq
subjecting the chemically surface treated hydrophobic and oleophilic coal to high
shear intermixing with an aqueous wash medium whereby additional ash and other hydrophilic
impurities are released into the aqueous medium and a hydrophobic coal phase floats
upon and separates from a water phase.
[0013] In the accompanying figures, Fig. 1 is a flow diagram illustrating the process of
the present invention whereby solid carbonaceous material, such as coal, is beneficiated.
[0014] Fig. 2 is a flow diagram illustrating a preferred manner by which solid carbonaceous
materials, such as coal, are beneficiated according to the present invention.
[0015] Fig. 3 is a further flow diagram depicting another preferred mode by which the present
invention is performed.
[0016] Fig. 4 is an illustration of a typical vessel which may be utilized in the practice
of the present invention.
[0017] In accordance with the present invention, a highly beneficiated coal product is produced
by a process which involves surface treating particles of coal in an aqueous medium
with a surface treating admixture comprising a polymerizable monomer, a polymerization
catalyst and a liquid organic carrier, thereby rendering said coal particles hydrophobic
and oleophilic. Thus, the process of this invention provides a highly beneficiated
coal product of relatively low water content which can be even further dehydrated
(dried) to a remarkable degree without the use of thermal energy. The ash content
of the coal prepared by the present process is reduced to low levels and mineral sulfur
compounds present are also removed. Moreover, the final coal product has enhanced
BTU content and can be burned as a solid or combined with fuel oil or water to produce
highly desirable beneficiated coal mixtures or slurries which are readily transportable
and cleanly burned.
[0018] As used herein, the term "beneficiation" is intended to include methods for cleaning
or otherwise removing impurities from a substrate, such as coal and to the recovery
of coal from coal streams, such as, for example, the recovery of coal from waste streams
in coal processing operations and the concentration or dewatering of coal streams
or slurries such as, for example, by the removal of water in, for example, coal slurry
pipelines.
[0019] In one embodiment for carrying out the present invention, wherein raw-mined coal
is employed as the feedstock, it is initially preferred to reduce raw mined coal or
other solid carbonaceous material to a fine diameter size and to remove unwanted rock,
heavy ash and the like materials collected in the mining operation. Thus, the coal
is pulverized and initially cleaned, usually in the presence of water, wherein the
coal is suspended and/or sufficiently wetted to permit fluid flow. The coal is pulverized
employing conventional equipment such as, for example, ball or rod mills, breakers
and the like.
[0020] It is generally desirable, although not necessary to the present process, to employ
certain water conditioning (treating) additives in the pulverization operation. Such
additives assist in rendering the ash more hydrophilic, which facilitates the separation
thereof, in a manner that will be discussed hereinafter. Typical additives which are
useful for purposes of this invention include conventional inorganic and organic dispersants,
surfactants, and/or wetting agents. Preferred additives for this purpose include sodium
carbonate, sodium pyrophosphate, and the like.
[0021] The coal-aqueous slurry formed in the pulverization operation is typically one having
a coal to water ratio of from about 0.5:1 to about 1:5 and preferably about 1:3 parts
by weight, respectively. If utilized, the water treating additives, hereinbefore described,
are employed in small amounts, usually, for example, from about 0.25 to about 5%,
based on the weight of dry coal. While it is generally recognized that more impurities
are liberated as the size of the coal is reduced, the law of diminishing returns applies
in that there is an economic optimum which governs the degree of pulverization. In
any event, for the purposes of this invention, it is generally desirable to crush
the coal to a particle size of from about 48 to about less than 325 mesh, preferably
about 80% of the particles being of about a 200 mesh size (Tyler Standard Screen Size).
[0022] Any type coal can be employed in the process of the present invention. Typically,
these include, for example, bituminous coal, sub-bituminous coal, anthracite, lignite
and the like. Other solid carbonaceous fuel materials, such as oil shale, tar sands,
coke, graphite, mine tailings, coal from refuse piles, coal processing fines, coal
fines from mine ponds or tailings, carbonaceous fecal matter and the like are also
contemplated for treatment by the process herein. Thus, for the purposes of this invention,
the term "coal" is also intended to include these kinds of other solid carbonaceous
fuel materials or streams.
[0023] In carrying out the beneficiation process herein, the coal-aqueous slurry, containing
the pulverized coal, is contacted and admixed with a surface treating mixture comprised
of a polymerizable monomer, polymerization catalyst and a small amount of a liquid
organic carrier, such as fuel oil.
[0024] Any polymerizable monomer can be employed in the surface treating polymerization
reaction medium. While it is more convenient to utilize monomers which are liquid
at ambient temperature and pressure, gaseous monomers which contain olefinic unsaturation
permitting polymerization with the same or different molecules can also be used. Thus,
monomers intended to be employed herein may be characterized by the formula XHC=CHX'
wherein X and X' each may be hydrogen or any of a wide variety of organic radicals
or inorganic substituents. Illustratively, such monomers include ethylene, propylene,
butylene, tetrapropylene, isoprene, butadiene, such as 1,4-butadiene, pentadiene,
dicyclopentadiene, octadiene, olefinic petroleum fractions, styrene, vinyltoluene,
vinylchloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide,
acrolein, maleic acid, maleic anhydride, fumaric acid, abietic acid and the like.
[0025] A preferred class of monomers for the purposes of the present invention are unsaturated
carboxylic acids, esters, anhydrides or salts thereof, particularly those included
within the formula O wherein R is an olefinically RC-OR' unsaturated organic radical,
preferably containing from about 2 to about 30 carbon atoms, and R' is hydrogen, a
salt- forming cation such as alkali metal, alkaline earth metal or ammonium cation,
or a saturated or ethylenically unsaturated hydrocarbyl radical, preferably containing
from 1 to about 30 carbon atoms, either unsubstituted or substituted with one or more
halogen atoms, carboxylic acid groups and/or hydroxyl groups in which the hydroxyl
hydrogens may be replaced with saturated and/or unsaturated acyl groups, the latter
preferably containing from about 8 to about 30 carbon atoms. Specific monomers conforming
to the foregoing structural formula include unsaturated fatty acids such as oleic
acid, linoleic acid, linolenic, ricinoleic, mono-, di- and tri-glycerides, and other
esters of unsaturated fatty acids, acrylic acid, methacrylic acid, methylacrylate,
ethyacrylate, ethylhexylacrylate, tertiarybutyl- acrylate, oleylacrylate, methylmethacrylate,
oleylmeth- acrylate, stearylacrylate, stearylmethacrylate, laurylmethacrylate, vinylacetate,
vinylstearate, vinylmyristate, vinyllaurate, unsaturated vegetable seed oil, soybean
oil, rosin acids, dehydrated castor oil, linseed oil, olive oil, peanut oil, tall
oil, corn oil and the like. For the purposes of this invention, tall oil and corn
oil have been found to provide particularly advantageous results. Corn oil is especially
preferred. Moreover, it is to be clearly understood that compositions containing compounds
within the foregoing formula and in addition containing, for example, saturated fatty
acids such as palmitic, stearic, etc. are also contemplated herein. Also contemplated
herein as monomers are aliphatic and/or polymeric petroleum materials.
[0026] The amount of polymerizable monomer will vary depending upon the degree of surface
treatment desired. In general, however, monomer amounts of from about 0.005 to about
0.1%, by weight, of the dry coal are used.
[0027] The catalysts employed in the coal surface treating beneficiation reaction of the
present invention are any such materials commonly used in polymerisation reactions.
These include, for example, anionic, cationic or free radical catalysts. Free radical
catalysts or catalyst systems (also referred to as addition polymerization catalysts,
vinyl polymerization catalysts or polymerization initiators) are preferred herein.
Thus, illustratively, free radical catalysts contemplated herein include, for example,
inorganic and organic peroxides such as benzoyl peroxide, methylethyl ketone peroxide,
tert-butylhydroperoxide, hydrogen peroxide, ammonium persulfate, di-tert-butylperoxide,
tert-butyl-perbenzoate, peracetic acid and including such non-peroxy free-radical
initiators as the diazo compounds such as l,l'-bisazoisobutyronitrile and the like.
[0028] Typically, for the purposes of this invention, any catalytic amount (e.g. 1 pound
per ton of dry coal feed) of the foregoing described catalysts can be used.
[0029] Moreover, free radical polymerization systems commonly employ free radical initiators
which function to help initiate the free radical reaction. For the purposes herein,
any of those disclosed in the prior art, such as those disclosed, fpr example, in
U.S. Patent No. 4,033,852, incorporated by reference herein, may be used. Specifically
some of these initiators include, for example, water soluble salts, such as sodium
perchlorate and perborate, sodium persulfate, potassium persulfate, ammonium persulfate,
silver nitrate, water soluble salts of noble metals such as platinum and gold, sulfites,
nitrites and other compounds containing the like oxidizing anions, and water soluble
salts of iron, nickel chromium, copper, mercury, aluminum, cobalt, manganese, zinc,
arsenic, antimony, tin, cadmium, and the like.
[0030] particularly preferred initiators herein are the water soluble copper salts, i.e.
cuprous and cupric salts, such as copper acetate, copper sulfate and copper nitrate.
Most advantageous results have been obtained herein with cupric nitrate, Cu(NO
3)
2. Further initiators contemplated herein are disclosed in copending U.S. patent application
Serial No. 230,063 filed January 29, 1981. Among others, these initiators include
metal salts of organic moities
; typically metal salts of organic acids or compositions containing organic acids,
such as naphthenates, tallates, octanoates, etc. and other organic soluble metal salts,
said metals including copper, chromium, mercury, aluminum, antimony, arsenic, cobalt,
manganese, nickel, tin, lead, zinc, rare earths, mixed rare earths, and mixtures thereof
and double salts of such metals. The combination of copper and cobalt salts, particularly
cupric nitrate and cobalt naphthenate, have been found to provide particularly good
and synergistic results.
[0031] The amounts of free radical initiator contemplated herein are any catalytic amount
and generally are within the range of from about 10-1000 ppm (parts per million) of
the metal portion of the initiator, preferably 10-200 ppm,based on the amount of dry
coal.
[0032] . The surface treating reaction mixture of the present invention also includes a
liquid organic carrier.
[0033] This liquid organic carrier is utilized to facilitate contact of the surface of the
coal particles with the polymerization reaction medium. Thus, liquid organic carriers
included within the scope of this invention are, for example, fuel oil, such as No.
2 or No. 6 fuel oils, non-fuel oil liquid organic carriers, such as hydrocarbons including,
for example, benzene, toluene, xylene, hydrocarbons fractions, such as naphtha and
medium boiling petroleum fractions (boiling point 100°-180°C); dimethylformamide,
tetrahydrofuran, tetrahydrofurfuryl alcohol, dimethylsulfoxide, methanol, ethanol,
isopropyl alcohol, acetone, methylethyl ketone, ethyl acetate and the like and mixtures
thereof.
[0034] The amounts of liquid organic carrier, such as fuel oil, utilized in the surface
treatment reaction herein are generally in the range of from about 0.25 to about 5%
by weight,based on the weight of dry coal.
[0035] The surface treatment reaction of the present process is carried out in an aqueous
medium. The amount of water employed for this purpose is generally from about 65%
to about 95%, by weight, based on the weight of coal slurry.
[0036] The surface treating reaction conditions will, of course, vary, depending upon the
specific reactants employed and results desired. Generally, however, any polymerization
conditions which result in the formation of a hydrophobic or oleophilic surface on
the coal can be utilized. More specifically, typical reaction conditions include,
for example, temperatures in the range of from about 10°C to about 90°C, atmospheric
to nearly atmospheric pressure conditions and a contact time, i.e. reaction time,
of from about 1 second to about 30 minutes, preferably from about 1 second to about
3 minutes. Preferably, the surface treatment reaction is carried out at a temperature
of from about 15°C to about 80°C and atmospheric pressure for about 2 minutes. In
general, however, the longer the reaction time, the more enhanced are the results.
[0037] In the practice of the present invention, the coal can be contacted with the surface
treating ingredients by employing various techniques. For example, one technique is
to feed the aqueous pulverized coal slurry through a spraying means, e.g. nozzle,
and add the surface treating ingredients, i.e. polymerizable monomer, polymerization
catalyst, initiator and liquid organic carrier to the aqueous coal spray. The resultant
total spray mixture is then introduced to an aqueous medium contained in a beneficiation
vessel. In a preferred embodiment when this technique is used, the surface treated
aqueous coal mixture now in the vessel is recycled to the same vessel by re-feeding
the mixture to the vessel through at least one of said spraying means.
[0038] In a second technique, the aqueous coal slurry and surface treating ingredients,
i.e. polymerizable monomer, polymerization catalyst, initiator and liquid organic
carrier, are admixed in a premix tank and the resultant admixture is sprayed, e.g.
through a nozzle, into an aqueous medium contained in a beneficiation vessel. In another
and third technique, the resultant surface treated aqueous coal mixture, formed in
the beneficiation vessel in accordance with the foregoing described second technique,
is recycled to the same vessel by re-feeding the mixture to the vessel through at
least one of said spraying means.
[0039] As the surface treating reaction is completed, the hydrophobic and oleophilic beneficiated
coal particles float to the surface of the liquid mass. The ash, still remaining hydrophilic,
tends to settle and is removed to the water phase. Thus, the coal which results from
reaction with the hereinbefore described polymerizable surface treating mixture is
extremely hydrophobic and oleophilic and consequently readily floats and separates
from the aqueous phase, providing a ready water washing and for high recoveries of
coal. The floating hydrophobic coal is also readily seperablefrom the aqueous phase
(for example, a skimming screen may be used for the separation), which contains ash,
sulfur and other impurities which have been removed from the coal. While it is not
completely understood and while not wishing to be bound to any theory, it is believed
that the surface treatment polymerization reaction involves the formation of a polymeric
organic coating on the surface of the coal by molecular grafting of polymeric side
chains on the coal molecules.
[0040] In the practice of the present invention, the surface treated coal is preferably
subjected to at least one further wash step wherein the coal phase or phases are redispersed,
with good agitation, e.g. employing high speed mixers, as a slurry in fresh wash water.
Preferably, the initially surface treated coal is added to the wash water under atomizing
pressure through a spray nozzle thus forming minute droplets in air which are directed
with force onto and into the surface of the fresh water mass. In this manner, some
air is incorporated into the system.
[0041] By spraying, the wash water and the treated coal phase are intimately admixed under
high speed agitation and/or shear produced by the spray nozzle under super atmospheric
pressures. In this manner, the hydrophobic coal particles are jetted into intimate
contact with the wash water through one or more orifices of the spray nozzle thereby
inducing air inclusion, both in the passage through the nozzle as well as upon impingement
upon and into the air-water interface of the wash water bath.
[0042] U.S. Serial No. 230,058 and U.S. Serial No. 230,059 both filed on January 29, 1981
describe and claim a particularly effective method and apparatus for separating the
treated coal particles from unwanted ash and sulfur in the water phase utilizing an
aeration spray technique, wherein a coal froth phase is formed by spraying or injecting
the treated coal-water slurry into the surface of the cleaning water. Briefly, according
to the method and apparatus there described, the coal slurry is injected through at
least one selected spray nozzle, preferably of the hollow cone type, at pressures,
for example, at from about 15-20 psig, at a spaced-apart distance above the water
surface, into the water surface producing aeration and a frothing or foaming of the
coal particles, causing these particles to float to the water surface for skimming
off.
[0043] The foregoing described washings may be carried out with the treated coal slurry
in the presence of simply water at temperatues of, for example, about 10° to about
90°C, preferably about 30°C, employing from about 99 to about 65 weight percent water,based
on the weight of dry coal feed. Alternatively, additional amounts of any or all of
rhe heretofore described surface treating ingredients i.e. polymerizable monomer,
catalyst, initiator, liquid organic carrier, may also be added to the wash water.
Moreover, the washing conditions e.g. temperature, contact time, etc., utilized when
these ingredients are employed can be the same as if only water is present or the
washing conditions can be the same as those described heretofore with respect to surface
treatment of the coal with the surface treating mixture. Of course, water conditioning
additives may also be utilized during the washing steps, if desired.
[0044] After washing and/or additional surface treatment, the beneficiated coal may be dried
to low water levels simply by mechanical means, such as by centrifugation, pressure
or vacuum filtration etc., thus avoiding the necessity for costly thermal energy to
remove residual water. The beneficiated coal prepared by the process of this invention,
as hereinbefore described, generally contains from about 0.5% to about 10.0% by weight
ash,based on the weight of dry coal. Moreover, the sulfur content is from about 0.1%
to about 4% by weight, preferably about 0.3 to about 2%,based on the weight of dry
coal and the water content is from about 2% to about 25%, preferably from about 2%
to about 15%, by weight, based on the weight of dry coal.
[0045] At this point, the beneficiated coal can be used as a high energy content, ash and
sulfur reduced, fuel product. This beneficiated fuel product can be utilized in a
direct firing burner apparatus. Alternatively, the beneficiated particulate coal can
be blended with a carrier such as oil to provide a highly stable and beneficiated
coal slurry, such as a coal-oil mixture (COM). Oil, preferably fuel oil, such as No.
2, or No. 6, is blended with the beneficiated coal at any desired ratio- These ratios
typically include from about 0.5 to about 1.5 parts by weight coal to 1 part oil.
Preferably a 1:1 weight ratio is employed.
[0046] .It is also to be understood herein that the solid beneficiated coal product of the
present invention can also be redispersed in aqueous systems for pumping through pipelines.
If desired, to provide improved stability, selected metal ions, by way of their hydroxide
or oxide, can be added to the aqueous dispersion to preferably adjust the pH of the
slurry to above 7. Thus, for this purpose, alkali and/or alkaline earth metals, each
as, sodium, potassium, calcium, magnesium, etc., hydroxide or oxides,can be used.
Sodium hydroxide is preferred.
[0047] It has also been discovered herein that a stabilized coal-oil mixture can be provided
by the presence therein of the alkali or alkaline earth metal, e.g. (sodium, potassium.
calcium, magnesium, etc.) salt of a fatty acid of the formula
wherein R" is a saturated or an olefinically unsaturated organic radical. Thus, the
hereinbefore described unsaturated fatty acids, i.e.,
, wherein
[0048] R' is hydrogen and R is as defined before, are also intended for use herein. The
presence of these fatty acid salts in the beneficiated coal-oil mixtures of this invention
permits the ready dispersion of the coal in the fuel oil to produce a gel or other
structure which retards settling almost indefinitely. Other metal ions, in addition
to alkali or alkaline earth metals, are also useful to form stabilizing fatty acid
salts. These other metals include, for example, iron, zinc, aluminum and the like.
[0049] Generally, the amount of fatty acid utilized in forming the stable coal-oil mixture
will be from 3.0 to 0.5% by weight, based on the total weight of the mixture. The
amount of alkali or alkaline earth containing compound utilized to form the gel will
be sufficient to neutralize a substantial portion of the fatty acid and thus generally
varies from about 0.1 to 1.0% and usually 0.1% to 0.6% by weight, based on the total
weight of the coal-oil mixture. Preferably for a 50:50 coal-oil mixture, 1.5% by weight
acid and 0.3% by weight of neutralizing compound are added to the mixture.
[0050] An alternative practice herein to form stable coal-oil mixtures is to subject the
coal-oil mixture to an additional surface treating reaction where additional amounts
of polymerizable monomer and polymerization catalyst are added to a mixture of the
beneficiated coal in oil. In this case, the polymerizable monomer is again an unsaturated
carboxylic acid as described above, preferably tall oil, used in amounts of 3.0 to
0.5% by weight, preferably 1.5%, based on the total weight of the mixture. The polymerization
catalyst can be any of those described hereinbefore and is preferably cupric nitrate,
used in amountsof 2.0 to 10 ppm (parts per million), preferably 5 ppm, based on the
total weight of the mixture. The polymerizable monomer and polymerization catalyst
are added to the coal-oil mixture with stirring. Thereafter, alkali or alkaline earth
metal compound, such as sodium hydroxide, in an amount of 0.6 to 0.1%, by weight,
preferably 0.3%, based on the total weight of the mixture is added to the mixture.
The resulting product is a preferred stabilized coal-oil mixture.
[0051] Other processes which are suitable herein for preparing stable beneficiated coal-oil
mixtures are disclosed and claimed in U.S. Serial No. 230,055 and
U.S. Serial No. 230,064 both filed January 29, 1981. More particularly, U.S. Serial
No. 230,055 discloses and claims a process for forming stable coal-oil mixtures by
admixing beneficiated coal with a fatty acid ester, such as triglyceride, preferably
tallow, and a base, such as sodium hydroxide. Briefly, U.S. Serial No. 230,064 discloses
and claims a process for forming stabilized coal-oil mixtures by initially admixing,
under low shear conditions and at an elevated temperature, coal,oil, polymerizable
monomer and polymerization catalyst, and immediately thereafter subjecting the mixture
to a condition of high shear agitation at the same elevated temperature. The resultant
coal-oil mixture is then treated with a gelling agent, such as a hydroxide, like sodium
hydroxide, to form a stable beneficiated coal-oil mixture which is in the form of
a gel or thixotropic mixture.
[0052] The coal fuel oil products, i.e. coal-oil mixtures, of the present invention have
unique properties. For example, the present coal-oil mixtures are thixotropic, have
increased energy content, can utilize coal having low ash, low sulfur and low moisture
content and a wide variety of coals and can provide the potential for a widely expanded
market for coal as a fluid fuel thereby assisting in the conservation of petroleum.
[0053] With specific reference to the drawings herein, and particularly to Fig. 1, the process
of this invention is illustratively carried out, for example, by initially pulverizing
raw mined coal in pulverization zone 10 in the presence of water, and if desired,
water conditioning additives, to form an aqueous coal slurry. This aqueous coal slurry
is mixed in line 6 with surface treating reagents and/or additives, fed to line 6
from tanks 1, 2, 3, and 4 via line 5, and the thusly treated coal-slurry is introduced
to beneficiation zone 12, as shown. Tanks 1, 2, 3 and 4 contain, for example, polymerizable
monomer, free radical catalyst, free radical initiator and liquid organic carrier,
respectively. Raw mined coal is fed to zone 10 through line 23; water is fed through
line 21 and water conditioning additives may be introduced via line 25. Unwanted materials,
such as rock, are removed via line 27.
[0054] Water is generally the principal ingredient in beneficiation zone 12. Thus, the treated
coal-slurry being fed to zone 12 via line 6 is now hydrophobic and oleophilic and
after admixture with the wash water in zone 12, for example, by high speed mixer or
spray atomizer, readily floats on the surface of the water, thereby forcing a coal
froth phase and an aqueous phase in zone 12. The coal froth phase in zone 12 is readily
removed from zone 12 (for example, by skimming) through line 47 to provide a beneficiated,
i.e. clean, coal product according to the present invention having a reduced ash,
sulfur and water content. If desired, the clean coal from line 47 may be further dried
to remove additional water. The aqueous phase, remaining in zone 12, contains ash,
sulfur and other hydrophilic impurities and can be removed therefrom through line
11.
[0055] Alternatively, in carrying out the process of the present invention, in accordance
with Fig. 1, the surface treating reagents and/or additives may be admixed with the
aqueous coal slurry directly in beneficiation zone 12. Thus, these reagents and/or
additives can be introduced to zone 12 via line 31 (monomer), 33 (free radical catalyst),
35 (free radical initiator) 37 (water), 39 (liquid organic carrier). The coal slurry
is fed to zone 12 through line 6 and thusly admixed with the reagents in zone 12.
In another manner, as described hereinbefore, the surface treating additives can be
added to the coal spray coming from line 6.
[0056] With specific reference to Fig. 2, the process of this invention is illustratively
continuously carried out beginning with raw mined coal and ending with a coal-oil
mixture, although as indicated above other feedstocks and products, such as beneficiated
particulate coal and coal-water mixtures are also contemplated herein. Thus, referring
to Fi
g. 2, raw coal is initially pulverized in pulverization zone 10A in the presence of
water and, if desired, water conditioning additives, to form an aqueous coal slurry.
This aqueous coal slurry is fed to mix zone 11, through line 9, and admixed in zone
11 with surface treating reagents/ additives transported from reagent and/or additive
tanks lA, 2A and 3A and 4A, via line 8. Tanks 1A, 2A, 3A and 4A contain, for example,
polymerizable monomer, free radical catalyst, free radical initiator and liquid organic
carrier, respectively. Raw mined coal is fed to zone 10A through line 23A; water is
fed through line 21A and water conditioning additives may be introduced to zone 10A
via line 25A. The resultant admixture in mix zone 11 which contains the initial chemically
treated hydrophobic and oleophilic coal, is then introduced to a first beneficiation
zone 12A through line 29.
[0057] Alternatively, surface treating additives (or additional surface treating additives)
i.e., polymerizable monomer, polymerization catalyst, liquid organic carrier, hereinbefore
described, may be added directly to zone 12A (or zones 14 and 16), for example, through
line 31A (monomer), 33A (free radical catalyst), 35A (free radical initiator), 37A(water),
39A (liquid organic carrier), or they can be admixed beforehand along with the pulverized
coal slurry in lines leading to the beneficiation zones or vessels in the zones. In
the case where the surface treating reagents/additives are added directly to zone
12A, the coal slurry from zone 10A may be added directly to zone 12A via lines 9A
and 29. In addition, as described before, the coal slurry in the benefication vessel
can be recycled within each particular vessel to achieve greater mixing and separation.
[0058] The coal in zone 12A is extremely hydrophobic and oleophilic and after good agitation
with, for example, a high speed mixer or spray atomizer, a coal froth phase ensues
which is recovered. A screen may be advantageously used for the separation and recovery
of the flocculated coal. If desired, the recovered coal can be introduced, via lines
47 and 49 to a further sequence of wash steps, (e.g. zones 14 and 16) wherein with
further agitation of the recovered hydrophobic coal froth from zone 12A, provided
by high speed mixers, or other means, such as a spray atomizer, additional ash is
released to the water phase.
[0059] The water-wetted ash suspension phase, which is also formed in zone 12A, can be recovered
and can be sent to waste and water recovery, after which the water can be recycled
for reuse in the process as shown in Fig. 2. '
[0060] Alternatively, as indicated above, additional ash and sulfur is removed from the
beneficated coal froth phase by a series of counter-current water-wash steps, i.e.
the water phase in the wash zones 14 and 16 can be recycled to a previous wash zone,
as also ilustrated in Fig. 2. As indicated hereinbefore, in addition to water, zones
12A, 14 and 16 may also contain any or all of the foregoing chemical surface treatment
additives. The finally washed and surface treated coal exiting zone 16 via line 57
can be dried to a very low water level by, for example, centrifugation. The water
which is taken off in the centrifuge may also be recycled in the process as shown.
The recovered dry beneficiated coal product can be used directly as such as a solid
fuel or can be blended with a carrier to form a highly desirable beneficiated coal
slurry,such as a coal-oil-liquid fuel mixture.
[0061] In the preparation of the coal-oil mixture, Fig. 2 illustrates that the cry beneficiated
surface treated coal in fed to a coal-oil dispersion mixer, wherein, preferably hereinbefore
identified
acid, such as tall oil or naphthenic acid, may be added along with alkali metal hydroxide,
such as sodium or calcium hydroxide, to form a stable dispersion. If desired, further
surface treatment of the coal may be carried out in the coal-oil dispersion mixer
by adding a polymerizable monomer and polymerization catalyst to the admixture, as
described above, with or without subsequent addition of alkali or alkaline earth hydroxide.
Illustratively, coal-fuel dispersion can be carried out, either continuously or batchwise,
in, for example, conventional paint grinding equipment, wherein heavy, small grinding
media are used to shear the dispersion into a non- settling flowable coal-fuel product
of thixotropic nature.
[0062] It is to be understood herein that while the coal-oil admixture process illustrated
herein utilizes coals beneficiated as described herein, any coal, e.g. raw coal, coal
beneficiated by processes not herein described and the like, can also be employed
to form stable coal-oil mixtures in accordance with the process of the present invention.
[0063] Fig. 3 illustrates a further preferred mode by which the present invention may be
performed. With specific reference thereto, raw mined coal is introduced to pulverization
zone 70, through line 103 and pulverized therein in the presence of water which is
added via line 101. The water preferably contains a conditioning or treating additive
such as an inorganic or organic surfactant, wetting agent, dispersant or the like
which enhances the effectiveness of the water. Typical organic surfactants (such as
Triton X-100) include anionic, cationic and nonionic materials. Sodium pyrophosphate
is a preferred additive for the purposes of this invention. Conditioning ingredients
can be fed to zone 70 through line 105, for example. The aqueous coal slurry in zone
70 is sent to mix zone 82 via line 81 and admixed therein with reagents/additives
from tanks lB, 2B, 3
B and 4B containing polymerizable monomer, free radical catalyst, free radical initiator
and liquid organic carrier, respectively, for example.
[0064] The aqueous chemically treated hydrophobic and oleophilic coal slurry admixture formed
in zone 82 is fed to a first water wash zone 72 through line 107 and through high
shear nozzle D, whereby the velocity of the stream and the shearing forces are believed
to break up the coal phase stream into fine droplets which in turn can pass through
an air interface within wash zone 72 and impinge downwardly upon and forcefully jet
into the mass of the . continuous water in, e.g. a tank or tanks, contained therein.
If desired, further surface treating reagents, and/or additives, hereinbefore identified,
may be added to zone 72, (and/or zones 74 and 76), for example, through lines 109
(polymerizable monomer), 111 (free radical catalyst), 113 (free radical initiator),
115 (water), 117 (liquid organic carrier). The hydrophobic and oleophilic coal phase,
which ensues in zone 72, is then preferably, as shown, fed to a further sequence of
wash zones, via line 47.
[0065] Without intending to be limited to any theory or reaction mechanism, it is believed
to be helpful to discuss the phenomena thought to provide some of the advantageous
results achieved by the process herein. Thus, the high shearing forces created in
mixing, such as in nozzle D, are believed to assist in breaking up the coal-oil water
flocs as the dispersed particles forcefully enter the surface of the water in the
tank, thereby water-wetting and releasing ash and other impurities from the interstices
between the coal flocs. The coal flocs are thereby broken up so that the trapped ash
and other impurities are freed and introduced to the aqueous phase and thus separated
from the coal particles. The finely divided coal particles, whose surfaces are now
believed surrounded by polymer and liquid organic carrier, such as fuel oil, also
now contain (occluded) air sorbed in the atomized particles as a result of the shearing
effects of the nozzle. The combination of surface treatment and sorbed air causes
the flocculated coal to decrease in apparent density and to float on the surface of
the water, as a distinct coal froth phase. Thus, the coal particles assume a density
less than water, repel water by virtue of their increased hydrophobicity and quickly
float to the surface of the water.
[0066] By the foregoing technique, not only is ash substantially removed from the treated
coal product, but the entrapped air and the more hydrophobia and oleophilic coal surfaces
provide for a marked increase in the yield of total beneficiated treated coal, which
is ultimately recovered.
[0067] The still hydrophilic ash remains in the bulk aqueous phase and tends to settle downward
in the tank by gravity and is withdrawn from zone 72 in an ash-water stream 119 from
the base of the vessel. Some small amount of fine coal which may not be separated
completely can be transferred with the aqueous phase (withdrawn ash-water stream)
to a fine coal recovery zone 121, as shown in Fig. 3. Recovered coal fines can be
recycled via line 123 to the aqueous coal slurry in zone 70.
[0068] The wash process carried out in zone 72 can be repeated, employing a counter-current
wash system, whereby the coal progresses to a cleaner state through sequential introduction
to beneficiation zones 74 and 76, via lines 47 and 49, as illustrated in Fig. 3. Concomitantly,
clean wash water becomes progressively loaded with water soluble and water wetted
solid impurities extracted by the wash water.
[0069] As described before, the intimately admixed ash-water suspension coming from zone
72, containing some small amounts of particulate coal, is forwarded to fine coal recovery
zone 121 where high ash-low water solids are recovered and expelled for removal from
the process and the fine coal is recycled, as shown. The wash water can be further
treated,at 125,to control the condition of the recovered water prior to recycle. The
cleaned water is recycled to the original aqueous coal slurry or such other make-up
as the overall process may require to balance material flow.
[0070] As shown in Fig. 3, the coal froth phases resulting in zones 72 and 74 can be introduced
for further washings via nozzles E and F, respectively. In this manner, the coal particles
are again atomized. The velocity and high shear created by nozzles E and F once again
permit wash water contact with any ash still retained in the interstices of the coal
flocs, thereby assisting, in each wash step, to release ash to the aqueous phase.
The aqueous phases in zones 72, 74 and 76 float the flocculated coal-oil-air mass
to the top of the respective tanks.
[0071] The final coal froth phase in zone 76 is fed to a centrifuge, via line 57, for drying.
The beneficiated, clean coal phase is thereby remarkably dried without the necessity
for thermal energy, which is believed due to the reduced attraction for water between
the large coal-oil surfaces and the water physically occluded therebetween in the
flocculated dry coal recovered from the mechanical drying step.
[0072] The dry hydrophobic cleaned coal can be used advantageously at this point as a higher
energy content, ash and sulfur reduced solid fuel, which is referred to herein as
Product I. This solid fuel can be utilized in direct firing or to form beneficiated
coal slurries as described above.
[0073] As indicated above in another embodiment of this invention, a liquid fuel mixture,
which is easily pumped as a liquid, but which is of such rheological quality as to
form a thixotropic liquid, can also be provided. A thixotropic liquid is one that
has "structure" or tends to become viscous and gel-like upon standing quiescently,
but which loses viscosity and the "structure" or gel decreases markedly and rapidly
upon subjecting the thixotropic liquid to shearing stresses, as by agitation through
mixing and pumping processes or by heating.
[0074] In the practice of this invention, as illustrated by Fig. 3, the dry, beneficiated
coal Product I is mixed with a quantity of fuel oil (illustratively 1:1 by weight
and preferably heated to reduce viscosity especially in instances wherein the fuel
oil is of a heavy viscosity grade) in a mix tank to provide a pumpable fluid mixture.
[0075] Alternatively, the fuel-oil coal mixture in the mix zone may be subjected to an additional
surface treatment step, in line with the general reaction procedure employed in the
initial surface treatment beneficiation, hereinbefore described. For this purpose,any
of the hereinbefore identified polymerizable monomers, such as tall oil, corn oil,
and the like may be used and added to the mix zone along with any of the hereinbefore
identified polymerization catalysts and/or initiators. Moreover, the saturated carboxylic
acids hereinbefore described may be used alone or in combination with the unsaturated
acids, if desired. In the case wherein saturated acids are used alone, initiators
and catalysts need not be employed. Naphthenic acids are illustrative of saturated
acids which may be used.
[0076] . The admixture of surface treated coal, fuel oil and carboxylic acid can then be
substantially neutralized, with a water soluble alkali metal, such as from a hydroxide,
like sodium hydroxide, calcium hydroxide or mixtures thereof as indicated above to
form a stable coal-oil mixture. A liquid cleam coal-oil fuel mixture (Product II),
having no tendency to settle out, is storably recovered to provide a flowable high
energy source for a wide variety of end uses.
[0077] Alternatively, the beneficiated coal product I can be slurried with water to provide
coal-aqueous slurries or mixtures;
[0078] Fig. 4 illustrates a unit 55 which is suitable as a froth flotation vessel useful
in any of the wash and/or beneficiation zones employed in the present process. In
this unit, the aqueous coal slurry i.e. admixture of coal, water and preferably surface
treating reagents/additives, is sprayed into the vessel through lines 29 and through
spray nozzles 61. Additional surface treating reagents/ additives or any other desired
ingredients may also be added via lines 31, 33, 35, 37 and 39. In this vessel the
coal froth is skimmed off from the main portion of the vessel into a collector compartment
and can be introduced to the next zone via line 147, for example. The agueous-ash
phase in the main portion of the vessel is removed through line 41, for example.
[0079] It is to be understood herein that any of the zones illustrated in Figures 1-3 may
comprise a single vessel or zone or any number of vessels or zones arranged in a manner
suitable and in accordance with carrying out the invention as described herein.
[0080] In order that those skilled in the art may better understand how the present invention
may be practiced, the following examples are given by way of illustration and not
by way of limitation.
EXAMPLE 1
[0081] 200 grams of Pittsburgh seam coal having an initial ash content of 6.2% and initial
sulfur content of 1.5% is pulverized in the presence of 400 grams of water to a 200
mesh size using a ball mill grinding unit. The coal is transferred to a mixing vessel.
Into this vessel containing the coal is also introduced 0.05 grams of corn oil, 2.0
grams of #2 fuel oil, l.Occ. of a 5.0% solution of hydrogen peroxide in water and
2.0cc. of a cupric nitrate solution in water. The mixture is stirred and heated to
about 30°C for about 2 minutes. The resultant mixture is sprayed into a vessel containing
clean water and a frothing ensues. The coal, in the coal froth phase, is skimmed from
the water surface. The water phase containing large amounts of hydrophilic ash and
sulfur is discarded.
[0082] The cleaning procedure is repeated two further times using clean water and skimming
the frothed coal from the water surface. The particulate coal is then dried to a water
content of 15%, based on the weight of dry coal, using a laboratory Buchner funnel.
The ash content of the final particulate product is reduced to 1.5% and the sulfur
content is reduced to 0.8%.
EXAMPLE 2
[0083] The procedure of Example 1 is repeated using equivalent amounts of (a) coker gasoline;
(b) oleic acid; and (c) tall oil, each substituted for the corn oil. A cleaned coal
particulate product is produced having an ash content of about 3% and a moisture content
of about 15%, based on the weight of the dry coal.
EXAMPLE 3
[0084] The process of Example 1 is repeated using (a) Kittanning seam coal; (b) Illinois
#6 seam coal; and (c) lower Freeport seam coal in lieu of the Pittsburg seam coal.
A cleaned coal product having an ash content of about 3.0% and a moisture concentration
of 15%, based on the weight of the dry coal, is provided.
EXAMPLE 4
[0085] 200 grams, Illinois #6 coal reduced to about 1/4" size lumps and having an ash content
of 19.9%, is crushed to a particle size of about 28 mesh and then pulverized to 200
mesh in a laboratory ball mill in the presence of water to form-a coal-aqueous liquid
slurry. The liquid phase of the slurry contains about 65% water based on the total
weight of the slurry.
[0086] 50 mg. tall oil, 10 gms. of fuel oil, 250 milligrams sodium pryrophosphate, 100 milligrams
of cupric nitrate and 1.0 gms. H
20
2 (5% solution in water) are added to the above coal-aqueous slurry at about 30-40°C.
The hydrophobic, surface treated coal phase which ensues is recovered by removing
it from the surface of the aqueous phase on which it floats. The aqueous phase contains
the hydrophilic ash and is discarded.
[0087] Subsequent to several re-dispersions in clean soft water, containing sodium pyrophosphate,
at about 30°C, the surface treated coal is recovered. After filtering through a Buchner
funnel, the water content of the coal is about 15%. (Conventionally processed coal,
i.e., without chemical surface treatment, customarily retains from about 20-50
# water when ground to the same mesh size).
[0088] The recovered, mechanically dried, treated, beneficiated coal is admixed with 160
grams of fuel oil and an additional 5.0 gms. of tall oil is added thereto. After thorough
admixing at 85°C, caustic soda, equivalent to the acid value of the admixture, is
added thereto and further admixed therewith.
[0089] After standing for several months, no settling of the coal-liquid fuel mixture is
observed.
EXAMPLE 5
[0090] The process of Example 4 is repeated, except that gram equivalent amounts of the
following polymerizable monomers are substituted for the tall oil used in Example
4: (a) coker gasoline and (b) oleic acid.
[0091] The surface of the pulverized coal is similarly altered to result in strongly hydrophobic
coal particles which are processed similar to Example 4. In each case, the same amount
of tall oil is admixed with the recovered beneficiated coal, after drying. Acidity
is neutralized with caustic and similar coal-oil liquid suspensions are prepared,
which-all exhibit thixotropic quality depending upon the metal ion selected to displace
the sodium ion of the sodium hydroxide originally added. No settling is observed over
several weeks observation, independent of the monomer used in the surface treatment
reaction.
EXAMPLE 6
[0092] The process of Example 4 is repeated except that
2 grams of benzoyl peroxide are used in place of the hydrogen peroxide. Moreover, 2
grams of Triton-X-100 surfactant and 25 grams of sodium pyrophosphate are present
in the original slurry water. The ash in the resulting aqueous phase is filtered out
after treating with lime. The ash content.of the treated coal is reduced from about
19.9% to about 4.7% after five separate washings, wherein the water also contains
Triton-X-100 and sodium pyrophosphate. The tall oil used in the surface treatment
reaction and the tall oil employed in the formation of the stable coal-oil mixture,
is neutralized first with caustic soda and subsequently treated with an equivalent
amount of calcium hydroxide. The viscosity of the' coal-oil mixture is of a thixotropic
gel-like nature, indicating no settling is to be expected upon extended standing.
EXAMPLE 7
[0093] 235 grams of beneficiated coal having a 15% moisture content prepared in accordance
with Example 1 is placed in a vessel in which a stabilized coal-fuel oil mixture is
formed by the addition to said coal of 200 gms of #2 fuel oil, 6.0 gms. tall oil,
1.0 gms. of a 0.1% solution of H
2O
2 ( or benzoyl peroxide) in water (toluene), and 2.0 gms. of a 0.1% aqueous solution
of cupric nitrate. The mixture is stirred for about 1.0 minute at about 85°C. 1.5
gms. of sodium hydroxide is added tnereto and stirred for 5.0 minutes at about 65°C.
The resultant coal-oil mixture is a stabilized gel and remains so indefinitely.
[0094] Obviously, other modifications and variations of the present invention are possible
in the light of the above teachings. It is, therefore, to be understood that changes
may be made in the particular embodiments of this invention which arewithin the full
intended scope of the invention as defined by the appended claims.
1. A process for beneficiating coal comprising admixing coal in an aqueous medium with
a surface treating mixture comprising a polymerizable monomer, a polymerization catalyst
and a liquid organic carrier, thereby rendering said coal hydrophobic and oleophilic.
2. The process according to claim 1 further comprising subjecting the surface treated
hydrophobic and oleophilic coal to at least one water washing to remove quantities
of selected impurities and recovering the resultant beneficiated coal product.
3. The process according to claim 1 or 2 wherein said liquid organic carrier is a
non-fuel oil liquid organic carrier.
4. The process according to any of claims 1 to 3 wherein said liquid organic carrier
is selected from the group consisting of benzene, toluene, xylene, naptha and medium
boiling petroleum fractions, dimethylformamide, tetrahydrofuran, tetrahydrofurfuryl
alcohol, dimethylsulfoxide, methanol, ethanol, isopropyl alcohol, acetone, methylethyl
ketone, ethyl acetate and mixtures thereof.
5. The process according to any of claims 2 to 4 wherein said surface treated hydrophobic
and oleophilic coal is subjected to said at least one water washing by subjecting
said chemically treated coal to high shear intermixing with at least one aqueous wash
medium.
6. The process according to claim 5 wherein said high shear intermixing of said chemically
treated coal with said aqueous wash medium is carried out by jetting said coal into
said aqueous wash medium under atomizing pressure through a spray nozzle.
7. The process according to any of claims 1 to 6 wherein the polymerizable monomer
is selected from tall oil, corn oil or mixtures thereof and said polymerization catalyst
is comprised of a free radical catalyst and a free radical initiator selected from
inorganic water soluble metal salts, organic metal salts or mixtures thereof, wherein
the metal is selected from iron, zinc, antimony, arsenic, copper, tin, cadmium, silver,
gold, platinum, chromium, mercury, aluminum, cobalt, nickel or lead.
8. The process according to any of claims 1 to 7 wherein the polymerizable monomer
is corn oil, the catalyst is hydrogen peroxide and the free radical initiator is cupric
nitrate.
9. The process according to any of claims 2 to 8 wherein at least one of the water
washings is carried out in the presence of a member selected from a polymerizable
monomer, a polymerization catalyst, a liquid organic carrier or mixtures thereof.
'10. The process according to claims 1 or 2 wherein said polymerization catalyst is
selected from the group consisting of an anionic catalyst and a cationic catalyst.
11. A beneficiated coal product comprising surface treated, hydrophobic and oleophilic
coal having a reduced ash content within the range of from about 0.5 to about 10%
by weight based on the weight of dry coal.
12. A coal oil mixture comprised of an intimate blend of the beneficiated coal product
of any of the preceding claims and fuel oil.
13. A coal slurry comprising a mixture of the beneficiated coal product of any of
the preceding claims and a carrier.
14. The coal slurry according to claim 13 wherein the carrier is water.
15. A process for forming coal-oil mixture comprising admixing pulverized coal with
a member selected from a polymerizable monomer, a saturated fatty carboxylic acid
or mixtures thereof, and an alkali or alkaline earth hydroxide in the presence of
fuel oil.
16. The process of claim 15 wherein said polymerizable monomer is tall oil and said
hydroxide is selected from the group consisting of sodium hydroxide and calcium hydroxide.
17. A process for forming coal-oil mixtures comprising admixing pulverized coal with
a polymerizable monomer and a polymerization catalyst in the presence of fuel oil.
18. A process for forming coal-oil mixtures comprising admixing pulverized coal with
a polymerizable monomer and a polymerization catalyst in the presence of a fuel oil
to form a coal-oil mixture and thereafter intro- .ducing a hydroxide to said coal-oil
mixture to form a stabilized coal-oil mixture.
19. The process of claim 18 wherein said polymerizable monomer is tall oil, said polymerization
catalyst is comprised of a mixture of a free radical catalyst and free radical initiator,
and said hydroxide is sodium hydroxide.
20. The process of claim 19 wherein said free radical catalyst is hydrogen peroxide
and said free radical initiator is cupric nitrate.
21. A stabilized aqueous coal mixture comprised of an intimate admixture of the beneficiated
coal product of claim 11, water and a sufficient amount of an alkali or alkaline earth
metal hydroxide or oxide to provide said aqueous coal mixture with a pH of above 7.
22. The stabilized aqueous coal mixture of claim 21 wherein said alkali hydroxide is sodium hydroxide.
23. The process of claim 17 wherein said polymerization catalyst is selected from the
group consisting of an anionic catalyst and a cationic catalyst.
24. An arrangement for producing a beneficiated coal product, said arrangement comprising
in sequential combination:
coal pulverization means;
means for feeding pulverized coal from said coal pulverization means to a surface
treatment reaction zone;
a surface treatment reaction zone having means for introducing measured amounts of
chemical reactants for providing surface treatment of said coal in an aqueous medium;
means for introducing surface treated coal from said surface treatment reaction zone
to a water wash zone; and
at least one water wash zone having means for admixing ingredients introduced or contained
therein under high shear agitation.