CA1194305A - Coal-oil mixtures and process - Google Patents
Coal-oil mixtures and processInfo
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- CA1194305A CA1194305A CA000469670A CA469670A CA1194305A CA 1194305 A CA1194305 A CA 1194305A CA 000469670 A CA000469670 A CA 000469670A CA 469670 A CA469670 A CA 469670A CA 1194305 A CA1194305 A CA 1194305A
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Abstract
ABSTRACT OF THE DISCLOSURE
A process for forming coal-oil mixtures comprising admixing pulverized coal with a poplymerizable monomer and a polymerization catalyst in the presence of fuel oil. The mixture may then be stabilized by the introduction of a hydroxide.
A process for forming coal-oil mixtures comprising admixing pulverized coal with a poplymerizable monomer and a polymerization catalyst in the presence of fuel oil. The mixture may then be stabilized by the introduction of a hydroxide.
Description
COAL-OIL MIXTVRES AND PROCESS
:, This application is a divisional o~ A~plication Serial No~ 399,826, fil~d March 30, 1982.
This invention relates t~ a process for the ~ormation of coal-oil mixtures and beneficiated and stabili~ed coal-oil mixtures.
Known resources of coal and other solid carbon-aceous fuel materials in the world are far greater than lOthe known resources oE 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, 15cleaner burning, more easily retrievable and transportable fuels, such as petroleum and natural gas, has in the past, cast coal to a laraely supporting role in the ener~y field.
Current world events, however, have forced a new awareness of global energy requirements and of the avail-20ability of those resources which wil] adequately meet theseneeds. 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 25quantities of these resources, has sparked a new interest in t~e utilization of solid carbonaceous materials, particularly coal, as primary energy sources.
As a result, enormous efforts are being extended to make coal and related solid carbonaceous materials 30equivalent or better sources of energy, than pe-troleum or natural gas. In the case of coal, for example, much of ., ~$
lthis 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 5with 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.
Gasification and liquefaction of coal are two 10such known techniques. Detailed descriptions of various coal gasifaction and liquefaction processes may be found, for example, in the ~ncyclopedia of Chemical Technology, ~ . . . _ . _ Kirk-Othmer, Third Edition (1980) Volumne 11, pages 410~42~
and g49-~73. Typically, these techniques, however, require 15high energy input, as well as the utilization of hish temperature and high pressure equipment, thereby reducing their widespread feasibility and value.
Processes to make coal more readily liquefiable have also been developed. One such process is disclosed 20in U.S. Patent No. ~,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 25a liquefiable viscous product by extraction.
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 cf coal-oil and coal-aqueous mixtures are 30 described in the literature. Such liquid coal mixtures offer considerable advantages. In addition to being more 1 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 5 apparatus used for burning fuel oil. Such a capability can greatl~ facilitate the transition from fuel oil to coal as a primary energy sourceO Typical coa]-oil and coal-a~ueous mixtures and their preparation are disclosed in U.S. Patent No. 3,762,887, U.S. Patent No. 3,617,~95, 10 U.S. Patent No. 4,217,10g, U.S. Patent No. 4,101,293 and British Patent No. 1,523~193.
Regardlessl however, of the form in which the coal is ult`imately employed, the coal or coalcombustion products must be cleaned becausethey contain substantial amounts of 15sulfur, nitrogen compounds and mineral matter, including significant-quantities of meta-l impurities. During com-bustion 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 20must be cleaned to prevent pollution of the environment either by cleaning thecombustion products of the coal or the coal prior to burning.
Accordingly, physical as well as chemical coal eleaning (beneficiation) processes have been explored.
25In 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 30with the amount of fines to be treated, there is an economic optimum in size reduction. Moreover, grinding eoal even to extremely fine sizes may not be effective in removing all 1 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 electri-5 cal methods. In contrast to physical coal cleanin~, chemicalcoal cleaning techni~ues are in a very early stage of development. Known chemical coal cleaning techniques include/ for example, oxidative desulfurization of coal (sulfur is ronverted to a water-soluble form by air oxidation), 10 ferric salt leaching ~oxidation of pyritic sulfu~ with ferric sulfate), and hydrogen peroxide-sulfuric acid leaching.
Other-methods are also disclosed in the above-noted refer-ence to the Encyc]opedia of Chemical Technolo~y, Volume ~, pages 31~-322.
While it is obvious from the foregoing that enormous ef-forts 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 20 a wide scale as primary sources of energy.
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
:, This application is a divisional o~ A~plication Serial No~ 399,826, fil~d March 30, 1982.
This invention relates t~ a process for the ~ormation of coal-oil mixtures and beneficiated and stabili~ed coal-oil mixtures.
Known resources of coal and other solid carbon-aceous fuel materials in the world are far greater than lOthe known resources oE 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, 15cleaner burning, more easily retrievable and transportable fuels, such as petroleum and natural gas, has in the past, cast coal to a laraely supporting role in the ener~y field.
Current world events, however, have forced a new awareness of global energy requirements and of the avail-20ability of those resources which wil] adequately meet theseneeds. 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 25quantities of these resources, has sparked a new interest in t~e utilization of solid carbonaceous materials, particularly coal, as primary energy sources.
As a result, enormous efforts are being extended to make coal and related solid carbonaceous materials 30equivalent or better sources of energy, than pe-troleum or natural gas. In the case of coal, for example, much of ., ~$
lthis 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 5with 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.
Gasification and liquefaction of coal are two 10such known techniques. Detailed descriptions of various coal gasifaction and liquefaction processes may be found, for example, in the ~ncyclopedia of Chemical Technology, ~ . . . _ . _ Kirk-Othmer, Third Edition (1980) Volumne 11, pages 410~42~
and g49-~73. Typically, these techniques, however, require 15high energy input, as well as the utilization of hish temperature and high pressure equipment, thereby reducing their widespread feasibility and value.
Processes to make coal more readily liquefiable have also been developed. One such process is disclosed 20in U.S. Patent No. ~,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 25a liquefiable viscous product by extraction.
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 cf coal-oil and coal-aqueous mixtures are 30 described in the literature. Such liquid coal mixtures offer considerable advantages. In addition to being more 1 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 5 apparatus used for burning fuel oil. Such a capability can greatl~ facilitate the transition from fuel oil to coal as a primary energy sourceO Typical coa]-oil and coal-a~ueous mixtures and their preparation are disclosed in U.S. Patent No. 3,762,887, U.S. Patent No. 3,617,~95, 10 U.S. Patent No. 4,217,10g, U.S. Patent No. 4,101,293 and British Patent No. 1,523~193.
Regardlessl however, of the form in which the coal is ult`imately employed, the coal or coalcombustion products must be cleaned becausethey contain substantial amounts of 15sulfur, nitrogen compounds and mineral matter, including significant-quantities of meta-l impurities. During com-bustion 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 20must be cleaned to prevent pollution of the environment either by cleaning thecombustion products of the coal or the coal prior to burning.
Accordingly, physical as well as chemical coal eleaning (beneficiation) processes have been explored.
25In 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 30with the amount of fines to be treated, there is an economic optimum in size reduction. Moreover, grinding eoal even to extremely fine sizes may not be effective in removing all 1 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 electri-5 cal methods. In contrast to physical coal cleanin~, chemicalcoal cleaning techni~ues are in a very early stage of development. Known chemical coal cleaning techniques include/ for example, oxidative desulfurization of coal (sulfur is ronverted to a water-soluble form by air oxidation), 10 ferric salt leaching ~oxidation of pyritic sulfu~ with ferric sulfate), and hydrogen peroxide-sulfuric acid leaching.
Other-methods are also disclosed in the above-noted refer-ence to the Encyc]opedia of Chemical Technolo~y, Volume ~, pages 31~-322.
While it is obvious from the foregoing that enormous ef-forts 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 20 a wide scale as primary sources of energy.
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
2~ carrier, thereby providing a hydrophobic and oleophilic coal product adapted to the removal of further ash and sulfur by water separation techniques. The resultant pro-duct is highl~v suitable for the formation of beneficiated coal slurries and/or cleaned particulate coal.
Moreover, in a further embodiment of the present invention an improved process for beneficiating coal is L3~
1 provided which comprlses chemically surface treating coal in an aqueous n,edium to render said coal hydrophobic and oleophilic, thereafter separating the hydrophobic and oleophilic coal phase from the ash containiny water phase 5 and recovering the hydrophobic and oleophilic coal phase/
the particular improvement comprising sub~ecting the chem-ically s~lrface treated hydrophobic and oleophilic coal to high shear intermixing with an aqueous wash medi~lm whereby additional ash and other hydrophilic impurities are 10 released into the aqueous medium and a hydrophobic coal phase floats upon and separates from a water phase.
In the accompanying figures, Fig. 1 is a flow diagram illustrating the process of the present invention whereby solid carbonaceous material, such as coal 9 is 15 beneficiated.
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.
Pig. 3 is a further flow diagram depicting another 20 preferred mode hy which the present invention is performed.
Fig. 4 is an illustration of a typical vessel which ma~ be utilized in the practice of the present invention.
In accordance with the present invention, a highly beneficiated coal product is produced by a process 25 which involves surface treating particles of coal in an aqueous medium with a surface treating admixture com-prising a polymerizable monomer, a polymerization catalyst and a liquid organic carrier, thereby rendering said coal particles hydrophobic and oleophilic. Thus, the process 30 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
Moreover, in a further embodiment of the present invention an improved process for beneficiating coal is L3~
1 provided which comprlses chemically surface treating coal in an aqueous n,edium to render said coal hydrophobic and oleophilic, thereafter separating the hydrophobic and oleophilic coal phase from the ash containiny water phase 5 and recovering the hydrophobic and oleophilic coal phase/
the particular improvement comprising sub~ecting the chem-ically s~lrface treated hydrophobic and oleophilic coal to high shear intermixing with an aqueous wash medi~lm whereby additional ash and other hydrophilic impurities are 10 released into the aqueous medium and a hydrophobic coal phase floats upon and separates from a water phase.
In the accompanying figures, Fig. 1 is a flow diagram illustrating the process of the present invention whereby solid carbonaceous material, such as coal 9 is 15 beneficiated.
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.
Pig. 3 is a further flow diagram depicting another 20 preferred mode hy which the present invention is performed.
Fig. 4 is an illustration of a typical vessel which ma~ be utilized in the practice of the present invention.
In accordance with the present invention, a highly beneficiated coal product is produced by a process 25 which involves surface treating particles of coal in an aqueous medium with a surface treating admixture com-prising a polymerizable monomer, a polymerization catalyst and a liquid organic carrier, thereby rendering said coal particles hydrophobic and oleophilic. Thus, the process 30 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
3~
1 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 con-tent and can be burned 5as 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.
As used herein, the term "beneficiation" is intended to include methods for cleaning or otherwise removing impurities lOfrom 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 con-centration or dewatering of coal streams or slurries such as, for example, by the removal of water in, for example, coal 15slurry pipelines.
In one ernbodiment-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 car~onaceous material to a fine ~0 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 cl-eaned, usuallv in the presence of water, wherein the-coal is suspended and/or sufficiently wetted to permit fluid flow. The coal 25is pulverized employing conventional equipment such as, for e~ample, ball or rod ~nills, breakers and the like.
It is generally desirable, although not necessary to the present process, to employ certain water conditioning (treating) additives in the pulverization operation. Such 30 additives assist in rendering the ash more hydrophilic, which facilitates the separation thereof/in a manner that will be discussed hereinafter. Typical additives ~hich are useful for purposes of this invention include conventional inorganic and organic dispersants, surfactants, 5 and~or wetting agents~ Preferred additives for this purpose include sodium carbonate/ sodium pyrophosphate, and the like.
The coal-a~ueous slurry formed in the pulverization operation is typically one having a coal to water ratio of from about 0.5:1 to about 1:~ and preferably about 1:3 lO 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 15 size of tke coal is reduced, the law of diminishing returns applies in that there is an economic optimum which governs the degree of pulveri~ation. 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 20 than 325 mesh, preferably ahout ~0% of the particles being of about a 200 mesh size (Tyler Standard Screen Size).
~ ny type coal can be employed-in the proces-s of---the present invention. Typically, these include, for example, bituminous coal, sub-bituminous coal, anthracite, lignite 25 and the like. Other solid carbonaceous fuel materials, such as oil shale, tar sands, coke, graphite, mine tailings, coal from refuse pi]es, coal processing fines, coal fines from mine-ponds or tailings, carbonaceous fecal matter and the like are also contemplated for treatment by the 30process herein. Thus, for the purposes of this invention, the term "coal" is also intenAed to include these kinds of other solid carbonaceous fuel materials or streams.
~.19~3~ L
1 In caxrying out the beneficiation process herein, .
the coal~aqueous slurry, containing the pulverized coal, is contacted and admixed with a suxface treating mixture comprised o~ a polymerizahle monomer, polymeriz~tion catalyst 5 and a small amount of a liquid organic carrier, such as fuel oil.
Any polymerizable monomer can be employed in the sur-face treating polymerization reaction medium. While it is more convenient`to utilize monomers whic:h are liquid at ~mbient tem-10 perature a.nd pressure, gaseous monomers which contain olefinicunsaturation permitting polymerization with the same or dif-ferent 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 o~ a 15 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, 20 acrylonitrile, methacrylonitrile, acrylamide, methacrylamide,N-methylolacrylamide, acrolein, maleic acid, maleic anhydride, fumaric acid, abietic acid-and the like.
A preferred class of monomers:for the purposes of the present invention are unsaturated carboxylic acids, esters, 25 annydrides or salts thereof, particularly those included within the formula ~1 wherein R is an olefinically RC-OR' unsaturated organic radical, preferably containing from about 2 to about 30 carbon atoms, and R' is hydroyen, a salt-30 forming cation such as alkali metal, alkaline earth metalor ammonium cation, o.r a saturated or ethylenically un-l saturated hydrocarbyl radical, preferably containin~ from l to about 30 carbon atoms, either unsubstituted or sub- ;
stituted with one or more halogen atoms, carboxylic acid groups and/or hydroxyl groups in which the hydroxyl hydrogens 5 may 4e 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 fore-going structural formula include unsaturated fatty acids such as oleic acid, linoleic acid, linolenic, ricinoleic, lO mono-, di- and tri-glycerides, and other esters of unsat-urated fatty acids, acrylic acid, meth~crylic acld, methyl-acrylate, ethyacrylate, ethylhexylacrylate, tertiarybutyl-acrylate, oleylacrylate, methylmethacrylate, oleylmeth-acrylate, stearylacrylate, stearylmethacrylate J laurylmeth-15 acrylate, 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 20 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, ~or example, saturated fatty acids such as palmitic, stearic, etc. are 25 also contemplated herein. Also contemplated herein as monomers are aliphatic andjor polymeric petroleum materials.
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 3o 0.1%, by weight, o~f the dry coal are used.
L3~ii The catalysts employed in the coal surface treatir.g beneficiation reaction of the present invention are any such materials commonly used in polyrnerization reactions. These include, for example, anionic~ cationic or free radical catal~sts.
5 ~ree radical catalysts or catalyst systems (also referred to as addition poly~eri ation 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-butyl-hydroperoxide, hydrogen peroxide, ammonium Persulfate, di-tert-butylp~roxi*e, tert-butyl-perbenzoate, peracetic acid and in-cluding such non-peroxy ree-radical initiators as the diazo compounds such as l,l'-bisazoisobutyronitrile and the like.
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.
Moreover, free radical polymerization systems cornmonly employ free radical initiators which function 20 to help i~itiate the free radical reaction. For the purposes herein, any of those disclosed in the prior art, such as those disclosed, for example, in U.S. Patent No. 4,033,852, may be used. Specifically~
sorne of these initiators include, for example, water 25 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 30 chromium, copper, mercury, aluminum, cobalt, manganese, zinc, arsenic, antimony, tin, cadmium, and the like.
1 Particularly preferred initiators herein are the water soluble copper salts, i.e. cuprous and c~pric salts, such as copper acetate, copper sulfate and copper nitrate. Most advantageous results have been obtained herein with cupric 5 nitrate, Cu(N03)2. Further initiators contemplated herein include metal salts of organic moities, typically metal salts of organic acids or compositions containing 10 organic acids, such as naphthenates, tallates, octanoates, etc. and other organic soluble metal salt-s, 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 15 sa~ts of such metals. The combination of copper and cobalt s_lts, particularly cu ric nitrate and cobalt naphthenate, have been found to provide particularly good and synergistic results.
The amounts of free radical initiator con-templatea 20 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 10-2D0 ppm,based on the amount of dry coal.
The surface treating reaction mixture of the 25 present invention also includes a liquid organic carrier.
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, 3o for exam~le, fuel oil, such as No. 2 or No. ~ fuel oils, non-fuel oil li~uid organic caxriers, such as hydro-carbons including, ~or example, benzene, toluene, -12~
1 xylene~ hydrocarbons fractions, such as naphtha and medium boiling petroleum fractions (boiling point 100-180C~;
dimethylformamide, tetrahydrofuran, tetrahydrofurfuryl aleohol, dimethylsulfoxide, methanol, ethanol, isopropyl 5 alcohol, acetone, ~ethylethyl ketone, ethyl acetate and the like and mixtures thereof.
The amounts of liquid organie carrier, such as fuel oil, utilized in the surEace treatment reaction herein are generally in the range of from abQutO.25 -to about 5~ by lO weight,based on the weight of dry coal~
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 15 slurry.
The surface treating reaction-conditions wi-ll, of eourse, vary, depending upon the speeifie reactants ~employed and results desired. Generally, however, any ~polymerization eonditions whieh result in the formation 20 of a hydrophobic or oleophilie surface on the coal ean be utilized. More speeifieally, typieal reaction conditions inelude, for example, temperatures in the range of from about 10C to about 90C, atmospherie to nearly atmospherie pressure eonditions and a eontact time, i.e. reaetion time, 25 of from about 1 seeond to about 30 minutes, preferably from about 1 seeond to about 3 minutes. Preferably, ~he surfaee treatment reaction is carried out at a temperature of from about 15C to about 80C and atmospherie pressure for about 2 minutes. In general, however, the longer the 3O reaction time, the more enhanced are the results.
1 In the practice of the present invention, the coal can ~e contacted with the surface treating ingredients by employin~ various techniques. For example, one technique is to feed the aqueous pulverized coal slurry through a 5 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 10 beneficiation vessel. In a prefer:red 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.
~5 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 20aqueous 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 25the mixture to the vessel through at least one of said spraying means.
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 30 remaining hydrophilic, tends to settle and is removed to the water phase. Thus, the coal which results from reac-1 tion with the hereinbefore described polymeriza~le surfacetreating mixture is extremely hydrophobic and oleophilic and consequently readily Eloats and separates from the aqueous phase, providing a ready water washing and for high 5 recoveries of co~l. The floating hydrophobic coal is also readily seperablefrom the aqueous phase (for example, a skim-ming screen may be used for the separation), which contains ash, sulfur and o-~her impurities which have been removed from the coal. While it is not completely understood and while 10 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.
In the practice of the present invention, the surface-*reated 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, 20 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.
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 30 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.
l U.S. Patents 4,347,126 and 4 347,127 both issued on August 31, 1982, describe and claim a particularly effective method and apparatus for sepa-rating the treated coal particles from unwanted ash and 5 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 lO 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 15 these particles to float to the water surface for skimming off.
The foregoing described washings may be carried out with thé treated coal slurry in the presence of simply water at temperatues of, for example, about 10 to about 20 90C, ~referably about 30~C, employing from about 99 to about 6~5 weight percent water,based on the weight of dry coal feed. Alternatively, additional amounts of any or all of the heretofore described surface treating ingredients i.e. poly-merizable monomer, catalyst, initiator, li.quid organi.c 25 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 30 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.
3~
1 AEter washing and/or addi~ional 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 5 costly thermal energy to remove residual water.j 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 10 about 4% by weight, preferably about-0.3 to about-2P6,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.
~t this point, the beneficiated coal can be used as 15 a high energy contentl 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 20 as a coal-oil mixture (CO~). 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.
Pre.erably a 1:1 weight ratio is employed.
It is al:so to be understood herein that the solid beneficiated coal product of the present invention can also be redispersed in aqueous systems for pumping ~hrough pipe-lines. If desired, to-provide-improved stability, selected metal ions, by way of their hydroxide or oxide, can be added 30 to the aqueous dispersion to preferably adjust the pH of the slurry to above 7. Thus, for this purpose, alkali and/or alkaline earth me-tals, each as, sodium, potassium, calcium, magnesium, etc., hydroxide or oxides,can be used.
1 Sodium hydroxide is preferred.
It has also been discovered herein that a stabil-ized coal-oil mixture can be provided by the presence therein of the alkali or alkaline earth metal,e.g. (sodium, potas-5 sium, calcium, magnesium, etc.) salt of a ~atty acid of the formula 11 wherein R" is a saturated or an olefinicallyR"C-OH
unsaturated organic radical. Thus, the hereinbefore described unsaturated fatty acids, i.e., O r wherein RCOR' 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 15 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, ~inc, aluminum and the like.
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 util-ized to form the gel will be sufficient to neutralize a sub-25stantial portion of the fatty acid and thus generally variesfrom 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.
An alternative practice herein to form stable co~l-oil mixtures is to subject the coal-oil mixture to an -18- ~ 3~ ~
additional surface treating xeaction where additional amounts of polymer.izable monomer and polymerization catalyst are added to a mix-ture o~ 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 we.ight of the mixture. The polymerization catalyst can be any of those described hereinbefo:re and is preferably cupric nitrate, used in amounts of 2.0 to lO ppm (paxts 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 stir:ring. 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.
Another process which is suitable herein for prepar~
ing stable beneficiated coal-oil mixtures involves admixing 20 beneficiated coal with a fatty acid ester, such as triglyceride, preferably tallow, and a base, such a sodium hydroxide. A
further process is described and claimed in U.S. Patent
1 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 con-tent and can be burned 5as 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.
As used herein, the term "beneficiation" is intended to include methods for cleaning or otherwise removing impurities lOfrom 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 con-centration or dewatering of coal streams or slurries such as, for example, by the removal of water in, for example, coal 15slurry pipelines.
In one ernbodiment-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 car~onaceous material to a fine ~0 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 cl-eaned, usuallv in the presence of water, wherein the-coal is suspended and/or sufficiently wetted to permit fluid flow. The coal 25is pulverized employing conventional equipment such as, for e~ample, ball or rod ~nills, breakers and the like.
It is generally desirable, although not necessary to the present process, to employ certain water conditioning (treating) additives in the pulverization operation. Such 30 additives assist in rendering the ash more hydrophilic, which facilitates the separation thereof/in a manner that will be discussed hereinafter. Typical additives ~hich are useful for purposes of this invention include conventional inorganic and organic dispersants, surfactants, 5 and~or wetting agents~ Preferred additives for this purpose include sodium carbonate/ sodium pyrophosphate, and the like.
The coal-a~ueous slurry formed in the pulverization operation is typically one having a coal to water ratio of from about 0.5:1 to about 1:~ and preferably about 1:3 lO 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 15 size of tke coal is reduced, the law of diminishing returns applies in that there is an economic optimum which governs the degree of pulveri~ation. 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 20 than 325 mesh, preferably ahout ~0% of the particles being of about a 200 mesh size (Tyler Standard Screen Size).
~ ny type coal can be employed-in the proces-s of---the present invention. Typically, these include, for example, bituminous coal, sub-bituminous coal, anthracite, lignite 25 and the like. Other solid carbonaceous fuel materials, such as oil shale, tar sands, coke, graphite, mine tailings, coal from refuse pi]es, coal processing fines, coal fines from mine-ponds or tailings, carbonaceous fecal matter and the like are also contemplated for treatment by the 30process herein. Thus, for the purposes of this invention, the term "coal" is also intenAed to include these kinds of other solid carbonaceous fuel materials or streams.
~.19~3~ L
1 In caxrying out the beneficiation process herein, .
the coal~aqueous slurry, containing the pulverized coal, is contacted and admixed with a suxface treating mixture comprised o~ a polymerizahle monomer, polymeriz~tion catalyst 5 and a small amount of a liquid organic carrier, such as fuel oil.
Any polymerizable monomer can be employed in the sur-face treating polymerization reaction medium. While it is more convenient`to utilize monomers whic:h are liquid at ~mbient tem-10 perature a.nd pressure, gaseous monomers which contain olefinicunsaturation permitting polymerization with the same or dif-ferent 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 o~ a 15 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, 20 acrylonitrile, methacrylonitrile, acrylamide, methacrylamide,N-methylolacrylamide, acrolein, maleic acid, maleic anhydride, fumaric acid, abietic acid-and the like.
A preferred class of monomers:for the purposes of the present invention are unsaturated carboxylic acids, esters, 25 annydrides or salts thereof, particularly those included within the formula ~1 wherein R is an olefinically RC-OR' unsaturated organic radical, preferably containing from about 2 to about 30 carbon atoms, and R' is hydroyen, a salt-30 forming cation such as alkali metal, alkaline earth metalor ammonium cation, o.r a saturated or ethylenically un-l saturated hydrocarbyl radical, preferably containin~ from l to about 30 carbon atoms, either unsubstituted or sub- ;
stituted with one or more halogen atoms, carboxylic acid groups and/or hydroxyl groups in which the hydroxyl hydrogens 5 may 4e 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 fore-going structural formula include unsaturated fatty acids such as oleic acid, linoleic acid, linolenic, ricinoleic, lO mono-, di- and tri-glycerides, and other esters of unsat-urated fatty acids, acrylic acid, meth~crylic acld, methyl-acrylate, ethyacrylate, ethylhexylacrylate, tertiarybutyl-acrylate, oleylacrylate, methylmethacrylate, oleylmeth-acrylate, stearylacrylate, stearylmethacrylate J laurylmeth-15 acrylate, 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 20 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, ~or example, saturated fatty acids such as palmitic, stearic, etc. are 25 also contemplated herein. Also contemplated herein as monomers are aliphatic andjor polymeric petroleum materials.
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 3o 0.1%, by weight, o~f the dry coal are used.
L3~ii The catalysts employed in the coal surface treatir.g beneficiation reaction of the present invention are any such materials commonly used in polyrnerization reactions. These include, for example, anionic~ cationic or free radical catal~sts.
5 ~ree radical catalysts or catalyst systems (also referred to as addition poly~eri ation 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-butyl-hydroperoxide, hydrogen peroxide, ammonium Persulfate, di-tert-butylp~roxi*e, tert-butyl-perbenzoate, peracetic acid and in-cluding such non-peroxy ree-radical initiators as the diazo compounds such as l,l'-bisazoisobutyronitrile and the like.
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.
Moreover, free radical polymerization systems cornmonly employ free radical initiators which function 20 to help i~itiate the free radical reaction. For the purposes herein, any of those disclosed in the prior art, such as those disclosed, for example, in U.S. Patent No. 4,033,852, may be used. Specifically~
sorne of these initiators include, for example, water 25 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 30 chromium, copper, mercury, aluminum, cobalt, manganese, zinc, arsenic, antimony, tin, cadmium, and the like.
1 Particularly preferred initiators herein are the water soluble copper salts, i.e. cuprous and c~pric salts, such as copper acetate, copper sulfate and copper nitrate. Most advantageous results have been obtained herein with cupric 5 nitrate, Cu(N03)2. Further initiators contemplated herein include metal salts of organic moities, typically metal salts of organic acids or compositions containing 10 organic acids, such as naphthenates, tallates, octanoates, etc. and other organic soluble metal salt-s, 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 15 sa~ts of such metals. The combination of copper and cobalt s_lts, particularly cu ric nitrate and cobalt naphthenate, have been found to provide particularly good and synergistic results.
The amounts of free radical initiator con-templatea 20 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 10-2D0 ppm,based on the amount of dry coal.
The surface treating reaction mixture of the 25 present invention also includes a liquid organic carrier.
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, 3o for exam~le, fuel oil, such as No. 2 or No. ~ fuel oils, non-fuel oil li~uid organic caxriers, such as hydro-carbons including, ~or example, benzene, toluene, -12~
1 xylene~ hydrocarbons fractions, such as naphtha and medium boiling petroleum fractions (boiling point 100-180C~;
dimethylformamide, tetrahydrofuran, tetrahydrofurfuryl aleohol, dimethylsulfoxide, methanol, ethanol, isopropyl 5 alcohol, acetone, ~ethylethyl ketone, ethyl acetate and the like and mixtures thereof.
The amounts of liquid organie carrier, such as fuel oil, utilized in the surEace treatment reaction herein are generally in the range of from abQutO.25 -to about 5~ by lO weight,based on the weight of dry coal~
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 15 slurry.
The surface treating reaction-conditions wi-ll, of eourse, vary, depending upon the speeifie reactants ~employed and results desired. Generally, however, any ~polymerization eonditions whieh result in the formation 20 of a hydrophobic or oleophilie surface on the coal ean be utilized. More speeifieally, typieal reaction conditions inelude, for example, temperatures in the range of from about 10C to about 90C, atmospherie to nearly atmospherie pressure eonditions and a eontact time, i.e. reaetion time, 25 of from about 1 seeond to about 30 minutes, preferably from about 1 seeond to about 3 minutes. Preferably, ~he surfaee treatment reaction is carried out at a temperature of from about 15C to about 80C and atmospherie pressure for about 2 minutes. In general, however, the longer the 3O reaction time, the more enhanced are the results.
1 In the practice of the present invention, the coal can ~e contacted with the surface treating ingredients by employin~ various techniques. For example, one technique is to feed the aqueous pulverized coal slurry through a 5 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 10 beneficiation vessel. In a prefer:red 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.
~5 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 20aqueous 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 25the mixture to the vessel through at least one of said spraying means.
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 30 remaining hydrophilic, tends to settle and is removed to the water phase. Thus, the coal which results from reac-1 tion with the hereinbefore described polymeriza~le surfacetreating mixture is extremely hydrophobic and oleophilic and consequently readily Eloats and separates from the aqueous phase, providing a ready water washing and for high 5 recoveries of co~l. The floating hydrophobic coal is also readily seperablefrom the aqueous phase (for example, a skim-ming screen may be used for the separation), which contains ash, sulfur and o-~her impurities which have been removed from the coal. While it is not completely understood and while 10 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.
In the practice of the present invention, the surface-*reated 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, 20 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.
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 30 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.
l U.S. Patents 4,347,126 and 4 347,127 both issued on August 31, 1982, describe and claim a particularly effective method and apparatus for sepa-rating the treated coal particles from unwanted ash and 5 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 lO 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 15 these particles to float to the water surface for skimming off.
The foregoing described washings may be carried out with thé treated coal slurry in the presence of simply water at temperatues of, for example, about 10 to about 20 90C, ~referably about 30~C, employing from about 99 to about 6~5 weight percent water,based on the weight of dry coal feed. Alternatively, additional amounts of any or all of the heretofore described surface treating ingredients i.e. poly-merizable monomer, catalyst, initiator, li.quid organi.c 25 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 30 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.
3~
1 AEter washing and/or addi~ional 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 5 costly thermal energy to remove residual water.j 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 10 about 4% by weight, preferably about-0.3 to about-2P6,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.
~t this point, the beneficiated coal can be used as 15 a high energy contentl 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 20 as a coal-oil mixture (CO~). 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.
Pre.erably a 1:1 weight ratio is employed.
It is al:so to be understood herein that the solid beneficiated coal product of the present invention can also be redispersed in aqueous systems for pumping ~hrough pipe-lines. If desired, to-provide-improved stability, selected metal ions, by way of their hydroxide or oxide, can be added 30 to the aqueous dispersion to preferably adjust the pH of the slurry to above 7. Thus, for this purpose, alkali and/or alkaline earth me-tals, each as, sodium, potassium, calcium, magnesium, etc., hydroxide or oxides,can be used.
1 Sodium hydroxide is preferred.
It has also been discovered herein that a stabil-ized coal-oil mixture can be provided by the presence therein of the alkali or alkaline earth metal,e.g. (sodium, potas-5 sium, calcium, magnesium, etc.) salt of a ~atty acid of the formula 11 wherein R" is a saturated or an olefinicallyR"C-OH
unsaturated organic radical. Thus, the hereinbefore described unsaturated fatty acids, i.e., O r wherein RCOR' 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 15 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, ~inc, aluminum and the like.
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 util-ized to form the gel will be sufficient to neutralize a sub-25stantial portion of the fatty acid and thus generally variesfrom 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.
An alternative practice herein to form stable co~l-oil mixtures is to subject the coal-oil mixture to an -18- ~ 3~ ~
additional surface treating xeaction where additional amounts of polymer.izable monomer and polymerization catalyst are added to a mix-ture o~ 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 we.ight of the mixture. The polymerization catalyst can be any of those described hereinbefo:re and is preferably cupric nitrate, used in amounts of 2.0 to lO ppm (paxts 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 stir:ring. 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.
Another process which is suitable herein for prepar~
ing stable beneficiated coal-oil mixtures involves admixing 20 beneficiated coal with a fatty acid ester, such as triglyceride, preferably tallow, and a base, such a sodium hydroxide. A
further process is described and claimed in U.S. Patent
4,306,883 granted December 22, 1981, which describes a process for Porming 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 condi-tion 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 bene-ficiated coal-oil mixture which is in the form of a gel or thixotropic mixture.
The coal fuel oil products, i.e. coal-oil mixtures, of the present invention have unique properties.
For exmaple, 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 expanding market for coal as a fluid level thereby assisting in the conservation of petroleum.
With specific reference to the drawings herein, and particularly to Fig. 1, the process of thsi invention is illustratively carried out, for example, by initially pulverizing a 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 treated 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 benification zone 12, as shown. Tanks 1, 2, 3 and 4 con-tain, for example, polymerizable monomer, free radical cat-alyst, free radical initiator and liquid ortganic 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.
Water is generally the principal ingredient in benification zone 12. Thus, the treated coal-slurry 3f~i lbeing fed to zone 12 via line 6 is now h~drophobic and oleo~hilic and after admi~ture with the wash wa~er in zone 12, for example, by high speed mixer or spray atomizer, readily floats on the surface of the water, thereby 5forming a coal froth phase and an aqueous phase in zone 12.
The coal froth phase in zone 12 is readily removed ~rom 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 watex lOCntent. 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.
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 20via line 31 (monomer), 33 (free radical catalyst), 35 (Eree radical initiator) 37 (water), 39 (li~uid 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 25be added to the coal spray coming from line 6.
With specific reference to ~ig. 2, the process of this invention is illustratively continuously carried out beginning with raw mined coal and ending with a coal-oil mi~.ure, although as indicated above other ~eedstocks and 30Droducts, such as beneficiated particulate coal and coal-water mii:tures are also contemplated herein. Thus, referring to Pig. 2, raw coal is initially pulverized in pulverization zone lOA in the presence of water and, if desired, water conditioning addit:ives, to form an a~ueous coa] slurry. This -21~
1 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 lA, 2A, 3A and
The resultant coal-oil mixture is then treated with a gelling agent, such as a hydroxide, like sodium hydroxide, to form a stable bene-ficiated coal-oil mixture which is in the form of a gel or thixotropic mixture.
The coal fuel oil products, i.e. coal-oil mixtures, of the present invention have unique properties.
For exmaple, 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 expanding market for coal as a fluid level thereby assisting in the conservation of petroleum.
With specific reference to the drawings herein, and particularly to Fig. 1, the process of thsi invention is illustratively carried out, for example, by initially pulverizing a 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 treated 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 benification zone 12, as shown. Tanks 1, 2, 3 and 4 con-tain, for example, polymerizable monomer, free radical cat-alyst, free radical initiator and liquid ortganic 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.
Water is generally the principal ingredient in benification zone 12. Thus, the treated coal-slurry 3f~i lbeing fed to zone 12 via line 6 is now h~drophobic and oleo~hilic and after admi~ture with the wash wa~er in zone 12, for example, by high speed mixer or spray atomizer, readily floats on the surface of the water, thereby 5forming a coal froth phase and an aqueous phase in zone 12.
The coal froth phase in zone 12 is readily removed ~rom 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 watex lOCntent. 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.
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 20via line 31 (monomer), 33 (free radical catalyst), 35 (Eree radical initiator) 37 (water), 39 (li~uid 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 25be added to the coal spray coming from line 6.
With specific reference to ~ig. 2, the process of this invention is illustratively continuously carried out beginning with raw mined coal and ending with a coal-oil mi~.ure, although as indicated above other ~eedstocks and 30Droducts, such as beneficiated particulate coal and coal-water mii:tures are also contemplated herein. Thus, referring to Pig. 2, raw coal is initially pulverized in pulverization zone lOA in the presence of water and, if desired, water conditioning addit:ives, to form an a~ueous coa] slurry. This -21~
1 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 lA, 2A, 3A and
5 4A contain, for example, polymerizable monomer, free radical catalyst, free radical initiator and liquld organic carrier, respectively. Raw mined coal is fed to zone lOA through line 23A, water is fed through line 21A and water condi-tioning additives may be introduced -to zone lOA via line 10 25A. ~he resultant admixture in mix zone 11 which contains the initial chemically treated hydrophobic and 0120philic coal, is then-introduced to a first beneficiation zone --12A through line 29.
Alternatively, surface treating additives (or addi-15 tional 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), 20 39A (liquid organic carrier), or they can be admixed before-hand 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 lOA may be 25 added directly to zone 12A via lines 9A and 29. In addition, as descrihed before,the coal slurry in the benefication vessel can be recycled within each particular vessel to achiev greater mixing and separation.
The coal in zone 12A is extremely hydrophobic and 3 oleophilic and after good agitation with, for example, a high 1 speed mixer or spray atomizer, a coal froth phase ensues which is recoveled. 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 5 47 and 49 to a further sequence of wash steps, (e.g. zones 14 and 16) wherein with ~urther agitation of the recovered hyArophobic 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.
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 ~he process as shown-in Fig. 2.
Alternatively, as indicated above, additional ash 15 and sulfur is removed from the beneficated coal ~roth 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 aiso ilustrated in Fig. 2.
As indicated hereinbefore, in addition to water, zones 12A, 20 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~l6 via line 57 can be dried to a very low water level by, for example, centri-fugation. The water which is taken off in the centrifuge 25 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. `:
In the preparation of the coal-oil mixture, Fig. 2 3~
1 illustrates that the dry beneficiated surface treated coal is fed to a coal-oil dispersion mixer, wherein, preferabl~
hereinbefore identified O acid, such as tall oil R"C-OH
5 or naphthenic acid, may be add~d along with alkali metal hydroxide, such as sodium or calcium hydro~ide, to form a stable dispersion. If desired, ~urther surface treatment of the coal ma~ be carried out in the coal-oil dispersion mixer by adding a polymerizable monomer and polymerization cata-10 lyst to ~he admixture, as described above, with or without sub-sequent addition of alkali or alkaline earth hydrox1de.
Illustratively, coal-fuel dispersion can be carried out, eithe~ continuously or batchwise, in, for e~ample, con-ventional paint grinding equipment, wherein heavy, small 15 grinding media are used to shear the dispersion into a non-settling flowable-coal-fuel product of thixotropic nature. --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, 20 coal beneficiated b~ 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.
FigO 3 illustrates a further preferred mode by which the present invention may be performed. With specific 25 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, dis-30 persant or the like which enhances the e~fectiveness of thewater. Typical organic surfactants (such as Triton X-100) * Trade mark -2~-l include anionic, cationic and nonionic materials. Sodium pyrophospha~e 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 5 in zone 70 is sent to mix zone ~2 via line 81 and admixed therein with reagents/additives from tanks lB, 2B, 3B and 4B containing polymerizable monomer, free radical catalyst, free radical initiator and liquid organic carrier, respectively, for example.
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 1-07 and through high shear nozzle D, whereby the velocity of the stream and the shearin~ forces are believed to break up the coal 15 ~hase 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 addi-20 tives, hereinbefore identified, may be added to zone 72,(and/or zones 74 and 76), for example~ through lines ~09 (polymerizable monomer), 111 (free radical catalyst), 113 (free radical initiator), 115 (water), 117 ~liquid organic carrier). The hydrophobic and oleophilic coal phase, which 25 ensues in zone 72, is then preferably, as shown, fed to a further sequence of wash zones, via line 47.
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 30 results achieved by the process herein. Thus, the high shear-ing forces created inmixing, such as in nozzleD, are believed 1 to assist in breaking up the coal-oil water flocs as the dis~
persed particles forcefully enter the surface of the water in the tank, thereby water~wetting and releasing ash ana other irnpurities from the interstices between the coal ~locs.
5 The coal flocs are thereby broken up so that the trappea ash and other impurities are freed and introduced to the a~ueous phase and thus separated from the coal particles~ The finely divided c~al particles, whose surfaces are now believea surrounded by polymer and liquid organic carrier, such 25 10 fuel oil, also now contain (occluded~ air sorbed in t~
atomize~ 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, 15 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.
By the foregoing technique, not only is ash 20 substantially removed from the treated coal product, but the entrapped air and the more hydrophobic and oleophilic coal surfaces provide for a marked increase in the yield of total beneficiated treated coal, which is ultimately recovered.
The still hydrophilic ash remains in the bulk 25 aqueous phase and tends to settle downward in the tank by ~ravity and is withdrawn ~rom zone 72 in an ash-wat~r streàm 119 from the base of the vessel. Some small amount of fine coal which may not be separated completely can be transrerred with the aqueous phase (withdrawn ash-water stream) to a fine 30 coal recovery zone 1~1~ as shown in Fig. 3. Recovered coal lfines can be recycled via line 123 to the aqueous coal slurry in zone 70.
The wash process carried out in zone 72 can be repeated, employing a counter-current wash system, whereby the 5coal progresses to a cleaner state through sequential intro-duction to beneficiation zones 74 and 76, via lines 47 and 49, as illustrated in Fig. 3~ Concomitantly, clean was~
water becomes progressively loaded with water soluble a~ld water wetted solid impurities extracted by the wash water.
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 15 the fine coal is recycled, as shown. The wash water can be furt~er 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 ~alance material 20 flow As shown in Fiy. 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 25 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 3o top of the respective tanks.
The final coal froth phase in zone 76 is fed to a centrifuge, via line 57, for drying. The beneficiated, clear.
1 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 5 dry coal recovered from the mechanical drying step.
The dry hydrophobic cleaned coal can be used advantageously at this point as a higher energy content, ash and sulf~r reduc2d solid fuel, which is referred to herein as Product I. 'hi5 solid fuel can be utili~ed in direct firing 10 or to ~orm beneficiated coal slurries as described above.
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
15 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 20 pumping processes or by heatin~.
In the practice of this inver.tion, 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 25 instances wherein the ~uel oil is of a heavy viscosity grade) in a mix tank to provide a pumpable f]uid mixture.
Alternatively, the fuel oil coal mixture in the mix z~ne may be subjected to an additional surface treatment step, in line with the general reaction procedure 3o employed in the initia]. surface treatment beneficiation, hereinbefore described. For this purpose,any of the herein-~3~
1 before 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 polymer-ization catalysts and/or initiators. Moreover, the saturated 5 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.
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 a~ove to form a stable coal-oil mixture.
15 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.
Alternatively, the beneficiated coal product I can be slurried with water to provide coal-aqueous slurries or 20 mixtures.
Fig. 4 illustrates a unit 55 which is suitable as a froth Elotation 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, 25 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 30 coal froth is skimmed off from the main portion of the lvessel into a collector compartment and can be introduced to the next zone vla llne 147, for example. The aqueous-ash phase in the main portion of the vessel is removed through line 41, for example.
It is to be unders-tood 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.
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.
3o 1 EXP~IPLE 1 200 srams 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 5 200 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 Z.Occ. of a cupric nitrate solu-10 tion in water. The mixture is stirred and heated to about30~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 phasel is skimmed from the water surface. The water phase containing large amounts of hydro-15 philic ash and sulfur is discarded.
The cleaning procedure is repeated two furthertimes 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, 20 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%.
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
5 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.
3o ` -32 ~3~
~XAMPLF 3 . .
The process of Example 1 is repeated using (a) ~ittanning seam coal; (b) Illinois #6 seam coal; and (c) lower Freeport seam coal in lieu of the Pittsburg seam 5 co~l. A cleaned coal product having an ash content of about 3.0~ and a moisture concentrcltion of 15~, based on the weight of the dry coal,is provided.
3o -33~
1 ~XAMPI.E 4 200 grams, Illinois ~6 coal reduced to about 1/4"
size lumps and having an ash content of 19.9~, is crushed 5 to a particle size of about 28 mesh and then pulverized to 200 mesh in a laboratory ball mill iIl the presence of water to form a coal-a~ueous liquid slurry. The liquid phase of the slurry contains about 65~ watex based on the total weight of the slurry.
50 mg. tall oil, 10 gms. of fuel oil, 250 milligrams sodium pryrophosphate, 100 milligrams of cupric nitrate and 1.0 gms. H2O2 (5~ solution in ~ater) are added to the above coal-aqueous slurry at about 30-40C. The hydropho~ic/ sur-face treated coal phase which ensues is recovered by removing 15 it from the surface of the aqueous phase on which it floats.
The aqueous phase contains the hydrophilic ash and is dis-carded.
Subsequent to several re-dispersions in clean soft water, containing sodium pyrophosphate, at about 3QC, the 20 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).
The recovered, mechanically dried, treated, beneficiaterl 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 85C, caustic soda, er~uivalent to the acid value of the admixture, 30 is added thereto and further admixed therewith.
After standing for several months, no settling of the coal-lirluid fuel mixture is observed.
-3~-1 EXAMPL~ 5 The process of Example 4 is repeated, except that gram equivalent amounts of the following polymerizable mono-5 mers are substituted for the tall oil used in Example 4:
(a) coker gasoline and ~b) oleic acid.
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, 10 the same amount of tall oil is admixed with the recovered heneficiated 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 15 originally added. No settling is observed over several weeks observation, independent of the monomer used in the surface treatment reaction.
3o ,3~i 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 5 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 wit~ lime. The ash con-tent of the treated coal is reducecl from about 19.9~ to about 4.7~ after five separate washings, wherein the water also 10 contains Triton-X-100 and sodium pyrophosphate. The tall oil-used in the surface treatment reaction and the tall oil employed in th~-formation of the stable coal-oil mixture, is neutralized first with caustic soda and sub-sequently treated with an equivalent amount of calcium 15 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.
3~i 235 grams of beneficiated coal having a 15%
moisture content prepared in accordance with Example 5 1 is placed in a vessel in which a stabilized coal-fuel oil mixture is formed by the addit:ion to said coal of 200 gms of #2 fuel oil, 6.0 gms. tall oil; 1.0 gms. of a 0.1% solution of H2O2 ( or benzoyl peroxide) in water (toluene), and 2.0 gms. of a 0.1% aqueous solution of lO cupric nitrate. The mixture is st:irred for about 1.0 minute at about 85C. 1.5 gms.-of sodium hydroxide is added thereto and stirred for 5.0 rninu-tes at about 65Co T~e resultant coal-oil mixture is a stabilized gel and remains so indefinitely.
3~
1 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 swhich arewithin the full intended scope of the invention as defined by the appended claims.
Alternatively, surface treating additives (or addi-15 tional 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), 20 39A (liquid organic carrier), or they can be admixed before-hand 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 lOA may be 25 added directly to zone 12A via lines 9A and 29. In addition, as descrihed before,the coal slurry in the benefication vessel can be recycled within each particular vessel to achiev greater mixing and separation.
The coal in zone 12A is extremely hydrophobic and 3 oleophilic and after good agitation with, for example, a high 1 speed mixer or spray atomizer, a coal froth phase ensues which is recoveled. 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 5 47 and 49 to a further sequence of wash steps, (e.g. zones 14 and 16) wherein with ~urther agitation of the recovered hyArophobic 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.
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 ~he process as shown-in Fig. 2.
Alternatively, as indicated above, additional ash 15 and sulfur is removed from the beneficated coal ~roth 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 aiso ilustrated in Fig. 2.
As indicated hereinbefore, in addition to water, zones 12A, 20 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~l6 via line 57 can be dried to a very low water level by, for example, centri-fugation. The water which is taken off in the centrifuge 25 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. `:
In the preparation of the coal-oil mixture, Fig. 2 3~
1 illustrates that the dry beneficiated surface treated coal is fed to a coal-oil dispersion mixer, wherein, preferabl~
hereinbefore identified O acid, such as tall oil R"C-OH
5 or naphthenic acid, may be add~d along with alkali metal hydroxide, such as sodium or calcium hydro~ide, to form a stable dispersion. If desired, ~urther surface treatment of the coal ma~ be carried out in the coal-oil dispersion mixer by adding a polymerizable monomer and polymerization cata-10 lyst to ~he admixture, as described above, with or without sub-sequent addition of alkali or alkaline earth hydrox1de.
Illustratively, coal-fuel dispersion can be carried out, eithe~ continuously or batchwise, in, for e~ample, con-ventional paint grinding equipment, wherein heavy, small 15 grinding media are used to shear the dispersion into a non-settling flowable-coal-fuel product of thixotropic nature. --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, 20 coal beneficiated b~ 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.
FigO 3 illustrates a further preferred mode by which the present invention may be performed. With specific 25 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, dis-30 persant or the like which enhances the e~fectiveness of thewater. Typical organic surfactants (such as Triton X-100) * Trade mark -2~-l include anionic, cationic and nonionic materials. Sodium pyrophospha~e 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 5 in zone 70 is sent to mix zone ~2 via line 81 and admixed therein with reagents/additives from tanks lB, 2B, 3B and 4B containing polymerizable monomer, free radical catalyst, free radical initiator and liquid organic carrier, respectively, for example.
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 1-07 and through high shear nozzle D, whereby the velocity of the stream and the shearin~ forces are believed to break up the coal 15 ~hase 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 addi-20 tives, hereinbefore identified, may be added to zone 72,(and/or zones 74 and 76), for example~ through lines ~09 (polymerizable monomer), 111 (free radical catalyst), 113 (free radical initiator), 115 (water), 117 ~liquid organic carrier). The hydrophobic and oleophilic coal phase, which 25 ensues in zone 72, is then preferably, as shown, fed to a further sequence of wash zones, via line 47.
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 30 results achieved by the process herein. Thus, the high shear-ing forces created inmixing, such as in nozzleD, are believed 1 to assist in breaking up the coal-oil water flocs as the dis~
persed particles forcefully enter the surface of the water in the tank, thereby water~wetting and releasing ash ana other irnpurities from the interstices between the coal ~locs.
5 The coal flocs are thereby broken up so that the trappea ash and other impurities are freed and introduced to the a~ueous phase and thus separated from the coal particles~ The finely divided c~al particles, whose surfaces are now believea surrounded by polymer and liquid organic carrier, such 25 10 fuel oil, also now contain (occluded~ air sorbed in t~
atomize~ 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, 15 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.
By the foregoing technique, not only is ash 20 substantially removed from the treated coal product, but the entrapped air and the more hydrophobic and oleophilic coal surfaces provide for a marked increase in the yield of total beneficiated treated coal, which is ultimately recovered.
The still hydrophilic ash remains in the bulk 25 aqueous phase and tends to settle downward in the tank by ~ravity and is withdrawn ~rom zone 72 in an ash-wat~r streàm 119 from the base of the vessel. Some small amount of fine coal which may not be separated completely can be transrerred with the aqueous phase (withdrawn ash-water stream) to a fine 30 coal recovery zone 1~1~ as shown in Fig. 3. Recovered coal lfines can be recycled via line 123 to the aqueous coal slurry in zone 70.
The wash process carried out in zone 72 can be repeated, employing a counter-current wash system, whereby the 5coal progresses to a cleaner state through sequential intro-duction to beneficiation zones 74 and 76, via lines 47 and 49, as illustrated in Fig. 3~ Concomitantly, clean was~
water becomes progressively loaded with water soluble a~ld water wetted solid impurities extracted by the wash water.
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 15 the fine coal is recycled, as shown. The wash water can be furt~er 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 ~alance material 20 flow As shown in Fiy. 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 25 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 3o top of the respective tanks.
The final coal froth phase in zone 76 is fed to a centrifuge, via line 57, for drying. The beneficiated, clear.
1 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 5 dry coal recovered from the mechanical drying step.
The dry hydrophobic cleaned coal can be used advantageously at this point as a higher energy content, ash and sulf~r reduc2d solid fuel, which is referred to herein as Product I. 'hi5 solid fuel can be utili~ed in direct firing 10 or to ~orm beneficiated coal slurries as described above.
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
15 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 20 pumping processes or by heatin~.
In the practice of this inver.tion, 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 25 instances wherein the ~uel oil is of a heavy viscosity grade) in a mix tank to provide a pumpable f]uid mixture.
Alternatively, the fuel oil coal mixture in the mix z~ne may be subjected to an additional surface treatment step, in line with the general reaction procedure 3o employed in the initia]. surface treatment beneficiation, hereinbefore described. For this purpose,any of the herein-~3~
1 before 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 polymer-ization catalysts and/or initiators. Moreover, the saturated 5 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.
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 a~ove to form a stable coal-oil mixture.
15 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.
Alternatively, the beneficiated coal product I can be slurried with water to provide coal-aqueous slurries or 20 mixtures.
Fig. 4 illustrates a unit 55 which is suitable as a froth Elotation 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, 25 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 30 coal froth is skimmed off from the main portion of the lvessel into a collector compartment and can be introduced to the next zone vla llne 147, for example. The aqueous-ash phase in the main portion of the vessel is removed through line 41, for example.
It is to be unders-tood 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.
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.
3o 1 EXP~IPLE 1 200 srams 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 5 200 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 Z.Occ. of a cupric nitrate solu-10 tion in water. The mixture is stirred and heated to about30~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 phasel is skimmed from the water surface. The water phase containing large amounts of hydro-15 philic ash and sulfur is discarded.
The cleaning procedure is repeated two furthertimes 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, 20 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%.
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
5 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.
3o ` -32 ~3~
~XAMPLF 3 . .
The process of Example 1 is repeated using (a) ~ittanning seam coal; (b) Illinois #6 seam coal; and (c) lower Freeport seam coal in lieu of the Pittsburg seam 5 co~l. A cleaned coal product having an ash content of about 3.0~ and a moisture concentrcltion of 15~, based on the weight of the dry coal,is provided.
3o -33~
1 ~XAMPI.E 4 200 grams, Illinois ~6 coal reduced to about 1/4"
size lumps and having an ash content of 19.9~, is crushed 5 to a particle size of about 28 mesh and then pulverized to 200 mesh in a laboratory ball mill iIl the presence of water to form a coal-a~ueous liquid slurry. The liquid phase of the slurry contains about 65~ watex based on the total weight of the slurry.
50 mg. tall oil, 10 gms. of fuel oil, 250 milligrams sodium pryrophosphate, 100 milligrams of cupric nitrate and 1.0 gms. H2O2 (5~ solution in ~ater) are added to the above coal-aqueous slurry at about 30-40C. The hydropho~ic/ sur-face treated coal phase which ensues is recovered by removing 15 it from the surface of the aqueous phase on which it floats.
The aqueous phase contains the hydrophilic ash and is dis-carded.
Subsequent to several re-dispersions in clean soft water, containing sodium pyrophosphate, at about 3QC, the 20 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).
The recovered, mechanically dried, treated, beneficiaterl 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 85C, caustic soda, er~uivalent to the acid value of the admixture, 30 is added thereto and further admixed therewith.
After standing for several months, no settling of the coal-lirluid fuel mixture is observed.
-3~-1 EXAMPL~ 5 The process of Example 4 is repeated, except that gram equivalent amounts of the following polymerizable mono-5 mers are substituted for the tall oil used in Example 4:
(a) coker gasoline and ~b) oleic acid.
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, 10 the same amount of tall oil is admixed with the recovered heneficiated 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 15 originally added. No settling is observed over several weeks observation, independent of the monomer used in the surface treatment reaction.
3o ,3~i 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 5 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 wit~ lime. The ash con-tent of the treated coal is reducecl from about 19.9~ to about 4.7~ after five separate washings, wherein the water also 10 contains Triton-X-100 and sodium pyrophosphate. The tall oil-used in the surface treatment reaction and the tall oil employed in th~-formation of the stable coal-oil mixture, is neutralized first with caustic soda and sub-sequently treated with an equivalent amount of calcium 15 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.
3~i 235 grams of beneficiated coal having a 15%
moisture content prepared in accordance with Example 5 1 is placed in a vessel in which a stabilized coal-fuel oil mixture is formed by the addit:ion to said coal of 200 gms of #2 fuel oil, 6.0 gms. tall oil; 1.0 gms. of a 0.1% solution of H2O2 ( or benzoyl peroxide) in water (toluene), and 2.0 gms. of a 0.1% aqueous solution of lO cupric nitrate. The mixture is st:irred for about 1.0 minute at about 85C. 1.5 gms.-of sodium hydroxide is added thereto and stirred for 5.0 rninu-tes at about 65Co T~e resultant coal-oil mixture is a stabilized gel and remains so indefinitely.
3~
1 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 swhich arewithin the full intended scope of the invention as defined by the appended claims.
Claims (7)
1. A process for forming coal-oil mixture compris-ing 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.
2. The process of claim 1, wherein said polymer-izable monomer is tall oil and said hydroxide is selected from the group consisting of sodium hydroxide and calcium hydroxide.
3. A process for forming coal-oil mixtures compris-ing admixing pulverized coal with a polymerizable monomer and a polymerization catalyst in the presence of fuel oil.
4. A process for forming coal-oil mixtures compris-ing 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 introducing a hydroxide to said coal-oil mixture to form a stabilized coal-oil mixture.
5. The process of claim 4 wherein said polymer-izable 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.
6. The process of claim 5 wherein said free radical catalyst is hydrogen peroxide and said free radical initiator is cupric nitrate.
7. The process of claim 3, wherein said polymer-ization catalyst is selected from the group consisting of an anionic catalyst and a cationic catalyst.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US267,773 | 1981-05-28 | ||
| US267,777 | 1981-05-28 | ||
| US06/267,777 US4406664A (en) | 1980-01-22 | 1981-05-28 | Process for the enhanced separation of impurities from coal and coal products produced therefrom |
| US06/267,773 US4412843A (en) | 1980-01-22 | 1981-05-28 | Beneficiated coal, coal mixtures and processes for the production thereof |
| CA000399826A CA1194304A (en) | 1981-05-28 | 1982-03-30 | Beneficiated coal, coal mixtures and processes for the production thereof |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000399826A Division CA1194304A (en) | 1981-05-28 | 1982-03-30 | Beneficiated coal, coal mixtures and processes for the production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1194305A true CA1194305A (en) | 1985-10-01 |
Family
ID=27167231
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000454876A Expired CA1231689A (en) | 1981-05-28 | 1984-05-22 | Apparatus for the beneficiation of coal |
| CA000469670A Expired CA1194305A (en) | 1981-05-28 | 1984-12-07 | Coal-oil mixtures and process |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000454876A Expired CA1231689A (en) | 1981-05-28 | 1984-05-22 | Apparatus for the beneficiation of coal |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA1231689A (en) |
-
1984
- 1984-05-22 CA CA000454876A patent/CA1231689A/en not_active Expired
- 1984-12-07 CA CA000469670A patent/CA1194305A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CA1231689A (en) | 1988-01-19 |
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