EP0032811B1 - Procédé d'amélioration du charbon et charbon ainsi amélioré - Google Patents

Procédé d'amélioration du charbon et charbon ainsi amélioré Download PDF

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Publication number
EP0032811B1
EP0032811B1 EP19810300152 EP81300152A EP0032811B1 EP 0032811 B1 EP0032811 B1 EP 0032811B1 EP 19810300152 EP19810300152 EP 19810300152 EP 81300152 A EP81300152 A EP 81300152A EP 0032811 B1 EP0032811 B1 EP 0032811B1
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European Patent Office
Prior art keywords
coal
water
particles
hydrophobic
oil
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP19810300152
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German (de)
English (en)
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EP0032811A2 (fr
EP0032811A3 (en
Inventor
Lester E. Burgess
Karl M. Fox
Phillip E. Mcgarry
David E. Herman
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Standard Oil Co
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Gulf and Western Industries Inc
Standard Oil Co
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Priority claimed from US06/114,357 external-priority patent/US4332593A/en
Priority claimed from US06/114,414 external-priority patent/US4304573A/en
Application filed by Gulf and Western Industries Inc, Standard Oil Co filed Critical Gulf and Western Industries Inc
Priority to AT81300152T priority Critical patent/ATE12790T1/de
Publication of EP0032811A2 publication Critical patent/EP0032811A2/fr
Publication of EP0032811A3 publication Critical patent/EP0032811A3/en
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Publication of EP0032811B1 publication Critical patent/EP0032811B1/fr
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L9/00—Treating solid fuels to improve their combustion
    • C10L9/10—Treating solid fuels to improve their combustion by using additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B9/00—General arrangement of separating plant, e.g. flow sheets
    • B03B9/005—General arrangement of separating plant, e.g. flow sheets specially adapted for coal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D3/00—Differential sedimentation
    • B03D3/06—Flocculation
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L1/00—Liquid carbonaceous fuels
    • C10L1/32—Liquid carbonaceous fuels consisting of coal-oil suspensions or aqueous emulsions or oil emulsions
    • C10L1/322—Coal-oil suspensions

Definitions

  • This invention relates to the art of beneficiating coal to reduce the amount of ash and sulfur in the coal and to improve the transportation characteristics of coal-oil mixtures. More particularly, this invention relates to an improved process for beneficiating coal and the products produced thereby.
  • Chemical grafting is made to occur in the presence of minor amounts of additive chemicals, generally a polymerizable unsaturated vinyl monomer is included used in amounts constituting from 0.5 to 10% by weight of the coal to be treated. Also included is a free radical catalyst system employed in amounts ranging from 0.001 to 0.10 wt percent of the monomer.
  • the free radical catalyst initiator disclosed in the patent consists of an organic peroxide catalyst added to the reaction in an amount between 0.05 to 2.5 wt percent of the monomer.
  • a quantity of free radical initiator metal ions, usually noble metals, are present in the free radical catalyst system, disclosed in that patent.
  • Monomers said to be used for chemical grafting to the coal included vinyl oleate, vinyl laurate stearate and other known monomers, unsaturated natural or synthztic organic compounds.
  • the metal ion catalyst initiator disclosed in the Horowitz patent is silver presented in the form of silver salts such as silver nitrate, silver perchlorate and silver acetate.
  • United States Letters Patent No 3,376,168 discloses that other metal ions, such as platinum, gold nickel or copper can be used when chemically grafting the polymerizable monomers onto the backbone of preformed polymers, illustratively, cellophane and dinitrated nitrocellulose. This patent does not relate to beneficiating coal.
  • coal is converted into a liquid fuel by pulverizing the coal and dispersing the coal powder in water with the aid of a polyelectrolyte and polyphosphate dispersants which undergo selective adsorption by the coal and impurity particles and thereby bring about differential charging of the coal and impurity particles.
  • the differentially charged particles can then be separated, for example, by virtue of their different settling rates in aqueous media, or different migration rates in an applied electric field, or even by virtue of the magnetic properties of coal particles containing magnetic impurities such as pyritic sulfur.
  • the beneficiated coal product of that process is therefore essentially hydrophilic and dispersible in water, in contrast to the beneficiated coal product of the present invention which is essentially hydrophobic and oleophilic.
  • the present invention is directed to the production of beneficiated coal product comprised of a particulate coal having a hydrophobic, oleophilic surface and being characterised by having low ash and sulfur content. Besides being suitable for direct use as a low-ash, low-sulfur fuel, the beneficiated coal product of this invention is also readily dispersible in heavy fuel oils to provide a readily transportable, stable liquid fuel product.
  • the present invention resides in a process for the beneficiation of raw coal by the removal of sulfur and ash-forming impurities therefrom, characterised by the steps of
  • a beneficiated coal-oil mixture comprising beneficiated coal particles produced as above dispersed in a hydrocarbon oil as the continuous phase. If desired this coal-oil mixture can be treated with a salt forming compound reactive with acidic groups on the surface of the disperse particles to provide a resultant mixture which is stable, gel like and thixotropic.
  • Such coal-oil mixtures may contain about 50 wt percent coal based on the total weight of the mixture.
  • free radical polymerization catalyst employed in the process of the present invention both organic or inorganic peroxides such as hydrogen peroxide, benzoyl peroxide, oxygen and air can be used.
  • Suitable free radical catalyst initiators comprise active metal ions such as ions of copper, iron, zinc, arsenic, antimony, tin and cadmium.
  • the organic unsaturated monomers which may be used in this invention are preferably liquid at room temperature and include oleic acid, vegetable seed oil fatty acid, unsaturated fatty acid, methyl and ethyl methacrylate, methyl and ethyl acrylate, acrylonitrite, vinylacetate, styrene, dicyclopentadiene, soybean oil, castor oil, tall oil and corn oil.
  • the monomers in this invention are water-insoluble organic acids having the general structure RCOOH wherein R is an ethylenically unsaturated group of at least 8 carbon atoms in size.
  • the process of this invention provides a beneficiated hydrophobic and oleophilic coal product of relatively low water content which can be further dehydrated to a remarkable degree without use of thermal energy.
  • the ash content of the coal is reduced to very low levels and mineral sulfur compounds present are removed.
  • the final coal product has enhanced BTU content, and can be burned as such or, as already indicated, combined with fuel oil to produce a mixture of coal and fuel oil as a burnable fuel.
  • Alkali metal and alkaline earth metal ions can thereafter be employed to convert the coal-oil mixture to a thixotropic gel-like fuel having excellent dispersion stability.
  • the thixotropic flowable fuels are useful as sources of thermal energy.
  • the dry coal product can, if desired, alternatively be redispersed in aqueous systems for pumping of the fluid aqueous coal slurry thus formed through pipelines and the like.
  • the process of the invention may be applied to the beneficiation of raw coal from a variety of sources, e.g., mine run, refuse piles, coal processing fines and the like.
  • the liquid hydrocarbon fuel oil present in minor amounts in the aqueous suspension medium during the graft polymerisation step is preferably a No. 2 fuel oil.
  • the above-identified components of the polymerisable mixture i.e. the monomer, the catalyst and the initiator, can be added at the initial process stages, e.g. during pulverization of the raw coal, and in the presence of the aqueous/ hydrocarbon suspension medium.
  • the chemical grafting reaction occurs in an aqueous medium in the presence of the above- described reactants.
  • the peroxide catalyst organic peroxide, oxygen, air, hydrogen peroxide
  • the peroxide catalyst is added to the described water insoluble unsaturated organic acid and the metal initiator of the free radical forming catalyst.
  • the organic unsaturated monomer becomes coated onto the coal particles. Without intending to be limited by any theory or mechanism, titration and extraction tests have indicated that the organic unsaturated monomer is believed chemically attached or grafted onto the coal surface. Further polymerization of the monomer is believed to result in the coal being coated with the polymer of the unsaturated monomer. By virtue of proper selection of monomer, the coal is rendered hydrophobic and oleophilic and can be immediately cleaned and recovered. The hydrophobic finely divided particles flocculate and float on the surface of the water.
  • the larger percentage of ash present in the original coal remains hydrophilic in surface character, it settles and tends to remain dispersed in the water and can be pumped off below the flocculated coal for further separation and disposal of ash and recovery of the water.
  • Lime can be used, if desired, to aid ash removal from the water phase.
  • the flocculated hydrophobic coal is washed, preferably by redispersal as a slurry in fresh wash water with good agitation.
  • a first product of the invention i.e. a particulate, beneficiated coal product having essentially hydrophobic and oleophilic surface characteristics.
  • This first product may be used as such as a "dry” fuel or subjected to further treatments hereinafter identified.
  • the dry first product can be used to prepare a fluid coal-oil-mixture (C.O.M.) by blending a further quantity of fuel oil with the treated "dry" coal at any desired ratio.
  • a preferred ratio is about 1:1 by weight.
  • the quality of thixotropy which gives structure of gel-like viscosity increase to the fuel oil extended coal.
  • the gel structure is unbroken.
  • the structure in the product is broken down, and the liquid flows normally but is non-Newtonian in nature.
  • the "drop point” temperature is influenced in particular by the selection of the metal ion.
  • the first product of the invention i.e. the mechanically dried, hydrophobic, oleophilic beneficiated coal particles
  • the first product of the invention can be dispersed in water to provide an aqueous coal dispersion suitable for pumping through pipelines for long distances, particularly those beneficiated coal products derived from carboxylic acid containing monomers and in which the acidic hydrogen atoms have subsequently been replaced by alkali metal atoms, especially sodium.
  • a further desirable, but optional, further treatment of the first product of the invention comprises subjecting the mechanically dried beneficiated coal particles to a second graft polymerization treatment carried out in precisely the same way as before, and using the same materials, that is to say by contacting the recovered particles in suspension in an aqueous medium containing a minor amount of water-insoluble liquid hydrocarbon fuel with a further quantity of the polymerization mixture comprising an organic monomer capable of undergoing free radial polymerization in the presence of a free radical catalyst and initiator, a free radical catalyst and a free radical catalyst initiator.
  • the monomer, the catalyst and the initiator the same materials as hereinbefore listed may be used, and as before, -COOH groups appearing in the final polymer can optionally be neutralized with alkali, alkaline earth or other metal containing neutralizing agents.
  • raw coal from the mine is reduced by conventional mine operations to relatively uniform top size particles as indicated, recovered fines from mine ponds or tailings can be equally used. If the larger 1" ⁇ size (2.5 cm) is used as a starting point a hydro roll crusher reduces the coal to about a 1/4" (6 mm) particle size coarse aqueous slurry.
  • a composite chemical grafting reagent mixture which may, or may not, contain the free radical polymerization catalyst. It has been found that hydrogen peroxide, H 2 0 2 , is satisfactory for this purpose.
  • the other components to be added are: the polymerizable water insoluble monomer, preferably an RCOOH acid where R is an ethylenically unsaturated group of at least 8 carbon atoms; a reactive metal ion site catalyst initiator salt; a minor amount of selected fuel oil, e.g. a No. 2 fuel oil.
  • the coarse coal slurry, now in the presence of the above chemical grafting reagent mixture, is further reduced in size to about 48 to 200 mesh (Tyler: 74 to 295 ⁇ m) or better.
  • the peroxide catalyst is added at this point, i.e., in the fine milling stage.
  • the coal becomes extremely hydrophobic as the chemical grafting occurs.
  • milling ceases the now hydrophobic coal flocculates and separates from the aqueous phase and thus from the remainder of the mill charge.
  • Considerable ash separates out in the water phase at this point.
  • the floating flocculated hydrophobic coal is recovered (a screen may be advantageously used for separation and recovery of the flocculated coal) and is passed through a plurality of wash steps wherein good agitation with high speed mixers and high shear of the hydrophobic coal-water wash dispersion as indicated above causes release of additional ash to the water phase, which ash is removed in the water phase.
  • the water-wetted ash suspension is recovered in further settling tanks and is sent to waste. The process water is recycled and re-used. Additional ash and sulfur can be removed from the grafted coal-oil conglomerate by a series of counter-current water-wash steps.
  • the chemically grafted pulverized coal (with most of the ash originally present in the raw removed) is dewatered to a very low water level by centrifuging.
  • the water content of the coal is in the order of 22 to 28%.
  • the water content of the grafted washed product can be in the order of 6-20% more usually 6-12% by weight.
  • the recovered "dry” beneficiation treated coal mass can be used directly as a "dry coal” product as a fuel without further addition of fuel oil.
  • a sufficient quantity of fuel oil is admixed with the beneficiated coal to produce a coal-oil mixture.
  • the mechanically dewatered coal (“dry" beneficiated treated coal is transferred to a coal- oil dispersion premixer; additional RCOOH acid is added along with additional initiator, catalyst and fuel oil.
  • the added acid can be the same as the unsaturated acid used in the chemical grafting step.
  • the acid used at this stage need not be unsaturated and saturated RCOOH acids such as stearic acid and the series of both crude and refined naphthenic acids recovered from refining of crude oils, etc. can be used.
  • water soluble alkali hydroxide metal can be added to the coal-oil mixture to neutralize free fatty acid hydrogen atoms and about the hydrophobic coal particles.
  • coal-oil mixture can be carried on continuously or batchwise, in, e.g., paint grinding equipment where heavy small grinding media are used to shear the dispersion into a non-settling fuel product of thixotropic nature by further metal ion source addition, such as calcium hydroxide to form an alkaline earth metal salt or soap.
  • metal ion source addition such as calcium hydroxide to form an alkaline earth metal salt or soap.
  • Other metal soaps are also useful as indicated herein.
  • the coal is introduced into a ball or rod mill, or other pulverizing and size reduction equipment.
  • the water is preferably treated with sodium pyrophosphate and/or other organic and inorganic water treatment materials. These materials operate as dispersants.
  • the aqueous slurry leaving the rod mill is put through a classifier and all particles more than about 48 mesh (Tyler: 295 p m) are returned for further size reduction.
  • the material leaving the classifier is passed to a surge tank where the density of the coal slurry is adjusted. Fine coal recovered from later processing can be introduced here.
  • the graft polymerization reaction generally occurs prior to the first of three water-wash steps where the chemical grafting reactants are added.
  • An aqueous chemical grafting reagent mixture when complete and useful for the initial graft initiating purposes herein contains about 1/2 Ibs (0.2 kg) tall oil fatty acids, 100 Ibs (45 kg) liquid water insoluble hydrocarbon (usually a selected grade of fuel oil), 1 Ib (.45 kg) of, illustratively, copper nitrate. (Other metal ions are also known to be useful to provide metal ion initiator sites.
  • the free radical processing peroxide catalyst which may be any of the known organic peroxides or inorganic peroxides (H 2 0 2 ) added directly or produced, in situ, with air or oxygen, but which is here preferentially hydrogen peroxide constitutes about 1-5/8 Ibs (.74 kg) of H 2 0 2 in solution of 30% H 2 0 2 -70% water strength.
  • the amount of chemical grafting catalyst polymerization mixture is exemplary of that required for treating about 2000 Ibs (908 kg) of the described, high pulverized coal product (by dry weight) in aqueous slurry.
  • Chemical grafting takes place very rapidly as the finely ground aqueous coal slurry leaves the surge tank and is intimately admixed with the chemical grafting or polymerization mixture described above.
  • This mixture of reactants 11 is pumped into the coal slurry discharge line 12, and is passed through an in-line mixer 13 under some pressure. Reaction takes place rapidly.
  • the coal surfaces now treated become more strongly oleophilic and hydrophobic than heretofore and are no longer wetted by the aqueous phase.
  • the stream of treated hydrophobic coal, wetted with polymer and fuel oil under pressure along with the accompanying water phase, is fed through a high shear nozzle D where the velocity of the stream and the shearing forces break up the coal flocculant-wash-water slurry into fine droplets which pass through an air interface within the wash tank (1) and impinge downwardly upon and forcefully jetted into the mass of the continuous water phase collected in the first wash tank (1).
  • the combined effects on the treated coal including the chemical grafting and fuel oil plus sorbed air, cause the flocculated coal to decrease in apparent density and to float on the surface of the water, separating the flocculated coal upwardly from the major water mass in wash tank (1) and then to overflow into the side collector (1A).
  • the still hydrophobic ash remains in the bulk water phase, tends to settle downward in wash tank (1) by gravity, and is withdrawn in an ash-water stream 14 from the base of the vessel.
  • Some small amount of fine coal which may not be separated completely is transferred with the water phase (withdrawn ash-water component) to a fine coal recovery station 15 (see Figure 2B).
  • the coal floc itself is of lesser density than coal itself due to the chemically polymerized organic layer on its surface which is less dense than water, the fuel oil present which is sorbed on the oleophilic-hydrophobic coal particle and sorbed air present in the floc.
  • the coal floc thereby assumes a density less than water and as it repels water by its increased hydrophobic quality quickly floats to the surface of the water present.
  • the ash on the other hand, remains hydrophilic and is, in effect, repelled by the treated coal surfaces, preferentially into the water phase. The density of the ash is greater than water and tends to settle out downwardly through the water mass.
  • the wash process of the first wash is repeated in essence through a counter-current wash system, the coal progressing to a cleaner state through sequential overflow and recovery in wash tanks (1), (2), and (3), while clean wash water becomes progressively loaded with water soluble and water wetted solid impurities extracted in the wash water as the cleaned water is recycled from water recycle line A into the second washed floc recovery tank (1B) through recycle water line 16.
  • Fresh or recycled treated wash water into tank (1 B) is dispersed into the floc and the resultant slurry removed by pump 17 from its base with the second washed overflow floc from tank (1 B) through an in-line mixer 18 into wash tank (3) through shear nozzle means F.
  • the separated ash-water wash water from wash tank (3) is removed from the base of wash tank (3) and is pumped counter-currently into the first washed floc tank (1A) where it is, in turn, pumped with the overflow floc collected in tank (1A) through an in-line mixer and nozzle E into wash tank (2).
  • the ash-water wash water containing any coal particles which did not floc and overflow into (1B) are removed by line 19 from the bottom section of wash tank (2) and are forced into a fine coal recovery line B-1 through which recovered coal is collected in a series of tanks at coal recovery 15 where fine coal otherwise lost is recovered.
  • the intimately admixed ash-water suspension containing some small amounts of particulate coal is separated in the wash water recovery system by passing it through settling and classifier apparatus and finally through a centrifuge where high ash-low water solids are recovered and expelled for removal from the process.
  • Suspended solids-free wash water is further treated at 20 to control the condition of the recovered water before recycle.
  • the clean treated process water is recycled to produce the original aqueous coal slurry and such other water make- up as the overall process may require when material flow is in balance.
  • the washed coal flocculate enters the final wash step from (1 B). From the in-line mixer 18 the floc-water slurry under pressure passes through shear nozzle F. The water-coal particle admixture is again atomized and collected in wash tank (3). Velocity and high shear through the nozzles D, E, and F allow wash water contact with any ash previously retained in the interstices of the coal floc, thereby assisting ash removal in each wash step.
  • the massive water phase created in the wash tanks (1), (2) and (3) floats the flocculated coal-oil-air mass to the top of the series of wash tanks (1), (2) and (3) and overflows the coal floc sequentially into collector tanks (lA), (lB) and (1 C). Fine floc overflow from tank (3) into tank (1 C) carries the washed floc in an aqueous stream to a mechanical de-watering means through line C.
  • the beneficiated, grafted, clean coal slurry is thereupon de-watered remarkably completely without requiring thermal energy. Illustrated here is a centrifuge, one advantageous mechanical means for the purpose. Note also, the 'dry' recovered coal product at this point in the process requires no thermal evaporation of water due to the reduced attraction for water between the large coal-oil surfaces and the water physically occluded therebetween in the flocculated 'dry' coal recovered from the mechanical drying step.
  • the dry hydrophobic cleaned coal can be used advantageously at this point as a higher energy content- sulfur reduced fuel which may be referred to as Product I. This fuel can be utilized in direct firing.
  • the principal practical purpose of this invention is to provide a liquid fuel which is easily pumped as a liquid, but which is of such rheological quality as to form a thixotropic liquid.
  • a thixotropic liquid is one that has 'structure' or tends to become viscous and gel-like upon standing quiescent but which loses viscosity and the 'structure' or gel decreases markedly and rapidly upon subjecting the thixotropic liquid to shearing stresses, as by agitation through mixing and pumping processes or by heating above the 'drop point'.
  • the dry, beneficiated, coal Product I coming from the conveyor, following mechanical water removal is mixed with a quantity of fuel oil (illustratively 1:1 by weight), preferably heated to reduce viscosity in cases where the fuel oil is of a heavy viscosity grade, in pre-mix tanks to again provide a pumpable fluid mixture.
  • fuel oil illustrated as 1:1 by weight
  • a preferred, but alternative practice is to subject the fuel-oil-coal mixture in the pre-mix tanks to an additional graft polymerization step, following the general reaction procedure as in the first graft polymerization.
  • the RCOOH acids are employed, as illustrated by tall oil fatty acids, oleic acid, etc.
  • Naphthenic acids are illustrative.
  • the non-fluid admixture of polymer surface grafted coal, fuel oil and RCOOH acid is substantially neutralized with a water soluble alkali metal and the fluidized particulate containing fuel oil-coal is pumped through an in-line mixer.
  • Alkaline earth metal ions from, for example, a calcium hydroxide solution are incorporated in the stream in an amount to react, at least in part, by double decomposition reactions to form the alkaline earth metal soaps or salts of the acid moiety previously neutralized with the alkali mete:.
  • Other metal ions may also be selected at this point to modify the 'drop point' of the final Product II, liquefied coal-oil mixture (C.O.M.).
  • the fluid coal-oil mass is then subjected to further high shear processing in a high shear milling device, such as is used in dispersing pigments in oils to produce paint products.
  • a high shear milling device such as is used in dispersing pigments in oils to produce paint products.
  • a liquid clean coal-oil-fuel mixture having no tendency to settle out, is storably recovered to provide a flowable high energy source for a wide variety of end uses.
  • a chemical graft polymerization mixture consisting of 500 mg tall oil, 100 g of fuel oil, 2-1/2 g sodium pyrophosphate and 1 g of copper nitrate were incorporated into the above mill batch in the initial mill loading. Before the mill was discharged 1-1/2 g of H 2 0 2 in solution (30% H 2 0 2 in water) was incorporated and graft polymerization of polymer on the coal surface was completed. The aqueous slurry was removed shortly thereafter from the mill, transferred to a settling vessel and the hydrophobic grafted coal was recovered by removing it from the surface of the water phase on which it floated. The water phase contained the hydrophobic ash which was discarded. Water used was between 30° and 40°C for all processing steps.
  • the agglomerated grafted coal was recovered. After filtering on a Buchner funnel the water content was about 15%. Coal normally processed without the grafting step will retain from 20-50% water when ground to the same mesh size. Washing can be effective at as low as 20°C but it is preferred to use at least 30°C water temperature.
  • the water preferably contains a phosphate conditioning agent.
  • the recovered, mechanically dried cleaned treated coal aggregate was admixed with oil and an additional 60 gm of tall oil. After thorough intermixing, caustic soda equivalent to the acid value of the mix was reacted with the free carboxyl groups of the tall oil.
  • Example II As in Example I, except 2 grams of butyl peroxide were used in the graft polymerization step in place of H 2 0 2 .
  • the water was treated with 2 grams of Triton X-100 (Registered Trade Mark) and 25 g of sodium pyrophosphate present in the originally slurry water.
  • the ash in the water phase was filtered out after treating with lime.
  • the ash content was reduced from about 4.28% to about 1.9% after five separate washings where the water was also treated with the same conditioning agents.
  • the tall oil (acids) used in the graft polymerization plus the tall oil added after processing were neutralized, first with caustic soda, and later treated with an equivalent amount of a water soluble alkaline earth metal (calcium hydroxide).
  • the recovered mechanically dried clean coal-oil product was further reduced with fuel oil to a flowable viscosity.
  • the viscosity quality, or rheology, of the system indicated it was of thixotropic gel-like nature, indicating no settling was to be expected upon standing.
  • the coal is reduced to about 200 mesh (Tyler: 74 pm) in a conditioned water (sodium tetra- phyrophosphate) slurry. 2000 grams of coal are in the mill. To the mill contents an'! added 1/2 gram tall oil acids, 100 grams fuel oil and 1 gram of metal initiator (Cu as copper nitrate). The batch is held at 30°C. Just as the milling is to be discontinued, there is added 1.64 grams of H 2 0 2 . The mill contents are pumped by a high shear centrifugal pump into a receiving vessel equipped with a high speed agitator.
  • the coal-water slurry is maintained in dispersed state in the receiving vessel for about ten minutes and is then pumped at high pressures through a fine spray nozzle where high shearing stresses atomize the slurry into fine droplets.
  • the air atomized droplets are directed onto and into the surface of a conditioned wash water containing vessel where the ash separates into the water and the now aerated coal particles rise and float on the surface and are recovered and vacuum filtered or centrifuged.
  • Initial ash content was 4.45 and the ash content of the treated clean coal product was 1.50%. It was also found that 1905 g clean coal was recovered or in excess of about 95% coal recovery.
  • Monomers previously used in chemical grafting and polymerization procedures in the main require pressure as they are gaseous. However, for the purposes of this invention where total economics of the process are extremely critical only monomers that are liquid at room temperature are used. Additionally, some of the prior art monomers are capable of producing a hydrophobic surface on the high surface areas of the pulverized coal, but are not as oleophilic in character as others. For the purposes of this invention and in the chemical grafting and polymerization step methyl and ethyl methacrylate, methyl and ethyl acrylate, acrylonitrile, vinylacetate, and styrene are useful as illustrative.
  • an unsaturated monomer which is a liquid at room temperatures and not having the polar carboxyl radical.
  • monomers found effective in chemical grafting of coal include: styrene, cracker gasoline, dicyclopentadiene, coker gasoline, polymer gasoline all of which are available from various refinery processes.
  • an unsaturated water insoluble monomeric organic acid having the general structure RCOOH where R is unsaturated and has at least 8 carbon atoms in the hydrocarbon moiety.
  • RCOOH unsaturated water insoluble monomeric organic acid
  • Economically attractive and extremely efficient is tall oil, a well known byproduct in paper manufacture which is available in various grades of purity. One grade is generally in excess of 95% oleic acid, most of the remainder being rosin acids. All of the unsaturated fatty acids available from vegetable seed oils, illustratively soyapean oil, fatty acids are useful. Dehydrated castor oil fatty acids are relatively expensive, but are useful.
  • RCOOH is advantageous. All of the above illustrated class of unsaturated long chain organic acids can be used.
  • R is saturated and this class is especially opened to include both highly refined naphthenic acid as well as a variety of fairly unique sources of naphthenic acid, illustratively Venezuelan crudes and certain bunker fuels known to contain many naphthenic acid fractions. Rosin acids are also useful.
  • Naphthenic acid may also be reactive through a resonance phenomena and be substantially equivalent in reactivity to the unsaturated RCOOH acids in the grafting step. While initial trials indicate some reactivity despite the fact that naphthenic acids are saturated, these latter acids have not yet been established as fully useful for the chemical grafting step. '
  • metal ion catalyst initiator tentatively includes all the catalytically active metal salts which can be used to provide polymerizably active metal ion sites on the pulverized coal surfaces.
  • Process water used is preferably between 30° and 40°C. If the temperature exceeds this generally optimum range it has been observed while there is no coal loss, ash removal drops off. If the temperature is below this range, not only does ash removal become less complete, but coal recovery drops off in the process. Washing can be carried out at lower temperatures but at about 30° overall improvement has been noted. Coal recovery of about 95% has been obtained with water content by vacuum filtration reduced to about 12% by weight. Water conditioning has been found useful.
  • Soxhlet extraction of our chemically grafted coal indicates very little free oil is removed (excluding the fuel oil process additions).
  • the acid value of the Product I coal was found substantially equivalent to the RCOOH acid used both in the grafting step or steps and the later RCOOH additions, whether saturated or unsaturated in the R group.
  • Zeolite water treatment may be advantageous in some instances.
  • Other methods of water conditioning is a specialized art, and may provide advantages over and beyond mere treatment with the known phosphate additives, illustratively tetra sodium pyrophosphate.
  • Minor additives of organic surfactants of the anionic, non-ionic and cationic classes may be valuable additions in some instances. Again, economics of their use weighed against advantages in ash removal and coal recovery may be quite specific to the coal being treated and the source of process water.
  • Coal recovery may be improved by a two stage addition of the chemical grafting additives.
  • two complete and separate graft polymerization reaction mixture additions and reactions may be carried out on the fine particle coal during the processing, if desired.
  • Ash reduction of the order of 66% (1.5% residual ash in coal products) has been recovered in some of the trial runs.
  • the percentages of coal and water will be variable, again depending on pulverising methods used as well as sources of coal and water. These ratios can be readily determined for a given set of conditions by one skilled in the coal- grinding arts.
  • Fuel oil used for production of fluidized coal is possible with all grades of fuel oil, even including #6 fuel oil, which is of extremely variable composition.
  • Coal loss during the washing steps has been of the order of 10%. Experience thus far indicates refinements of the present process will improve (reduce) losses of raw material.
  • Product II contains not more than about 6% water and the dry clean coal Product I is generally not more than about 12% water.

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Claims (19)

1. Procédé pour l'enrichissement de charbon brut par élimination du soufre et des impuretés génératrices de cendres qu'il contient, caractérisé par les opérations de
(a) broyage du charbon brut,
(b) mise en contact des particules de charbon brut broyé en suspension dans un milieu de suspension aqueux contenant de l'eau et 1 à 10 % en poids, rapporté au poids de particules de charbon brut broyé, d'un hydrocarbure combustible liquide, insoluble dans l'eau, avec un mélange polymérisable comprenant: i) un ou plusieurs monomères organiques susceptibles de subir une polymérisation en la présence d'un catalyseur et d'un promoteur de radicaux libres, ii) un catalyseur de radicaux libres et iii) un promoteur de radicaux libres, de façon à rendre préférentiellement les particules de charbon à la fois hydrophobes et oléophiles par la greffe- polymérisation dudit ou desdits monomères dans ledit milieu en présence desdites particules de charbon brut tout en laissant le soufre et les impuretés génératrices de cendres à l'état essentiellement hydrophile;
(c) séparation sélective des particules de charbon hydrophobes et oléophiles d'avec le milieu de suspension aqueux, en vue de laisser dans ledit milieu le soufre et lesdites impuretés gené- ratrices de cendres essentiellement hydrophiles;
(d) lavage à l'eau des particules de charbon hydrophobes et oléophiles séparées pour en éliminer plus complètement les impuretés hydrophiles; et
(e) séparation mécanique des particules de charbon hydrophobes et oléophiles lavées d'avec l'agent de lavage, afin de récupérer un produit charbon enrichi/huile comportant lesdites particules de charbon hydrophobes et oléophiles et de l'hydrocarbure liquide absorbé, ledit produit huile/charbon contenant moins d'environ 20 % en poids d'eau.
2. Procédé selon la revendication 1, caractérisé en ce qu'on ajoute les constituants i) et ii) du mélange polymérisable et le composant aqueux et hydrocarbure du milieu de suspension aux particules de charbon brut pendant le broyage, et l'on ajoute ultérieurement le constituant ii) du mélange de polymérisation.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que le catalyseur de radicaux libres est l'eau oxygénée.
4. Procédé selon la revendication 1, 2 ou 3, caractérisé en ce que le constituant monomère dudit mélange polymérisable est constitué par un ou plusieurs acides insaturés insolubles dans l'eau de formule RCOOH, où R est un groupe éthylénique insaturé comptant au moins 8 atomes de carbone.
5. Procédé selon la revendication 1, 2 ou 3, caractérisé en ce que le constituant monomère dudit mélange polymérisable comporte l'un ou plusieurs des corps suivants: acide oléique, acide gras d'huile de graines végétales, méthacrylate de méthyle ou d'éthyle, acrylate de méthyle ou d'éthyle, acrylonitrile, acétate de vinyle, styrène, dicyclopentadiène, huile de soja, huile de ricin, huile de blé ou tallôl.
6. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que dans l'opération d) on sépare les particules de charbon hydrophobes et oléophiles d'avec le milieu aqueux par flotation.
7. Procédé selon l'une quelconque des revendications 1 à 6, caractérisé en ce que dans l'opération d), on met les particules de charbon hydrophobes et oléophiles séparées en contact avec ladite eau de lavage dans des conditions de forte agitation, pour former par là de la mousse contenant lesdites particules, la mousse contenant ces particules étant ensuite récupérée en envoyée subir l'opération e) pour l'élimination mécanique de l'eau qu'elle contient.
8. Procédé selon la revendication 7, caractérisé en ce que l'opération de lavage d) comprend l'éjection d'un fluide aqueux à travers une buse à haut cisaillement sur la surface d'une masse d'eau de lavage de façon qu'il frappe à force celle-ci, amenant par là les particules de cendres hydrophiles restantes à se séparer en la phase aqueuse et les particules de charbon hydrophobes et oléophiles à floconner sous forme de phase huile/ charbon sur la surface de l'eau de lavage et la récupération des particules de charbon floconnées à partir de la surface de l'eau de lavage.
9. Procédé selon la revendication 7 ou 8, caractérisé en ce que dans l'opération d) on soumet les particules de charbon hydrophobe et oléophiles à une pluralité d'opérations de lavage-flotation successives.
10. Procédé selon l'une quelconque des revendications 1 à 9, caractérisé en ce qu'on soumet les particules de charbon hydrophobe et oléophile enrichi récupérées en tant que produit dans l'opération e) en suspension dans un milieu aqueux contenant une quantité mineure d'hydrocarbure combustible liquide insoluble dans l'eau avec un mélange polymérisable comprenant un monomère organique susceptible de subir une polymérisation de radicaux libres et la présence d'un promoteur et d'un catalyseur de radicaux libres à un traitement supplémentaire, pour former ainsi une nouvelle couche organique hydrophobe et oléophile greffée et polymérisée sur les particules de charbon enrichi, et l'on récupère les particules ayant subi le traitement supplémentaire à partir du milieu de suspension aqueux.
11. Procédé selon la revendication 10, caractérisé en ce que le monomère organique utilisé dans ledit traitement supplémentaire est un monomère tel que défini dans la revendication 4 ou 5.
12. Procédé selon l'une quelconque des revendications 1 à 11, caractérisé en ce que le monomère utilisé dans l'opération b), et/ou dans le traitement supplémentaire selon la revendication 10 ou 11, est un monomère contenant un ou plusieurs groupes acide carboxylique libre (-CO-OH), et après récupération des particules de charbon enrichi dans l'opération e), ou après récupération des particules ayant subi le traitement supplémentaire selon la revendication 10 ou 11, on neutralise les groupes acides carboxylique de la couche greffée-polymérisée après polymérisation par réaction avec un métal alcalin ou alcalino-terreux ou autre agent neutralisant contenant un métal.
13. Procédé selon l'une quelconque des revendications 1 à 12, caractérisé en ce que ledit hydrocarbure liquide insoluble dans l'eau présent dans la suspension aqueuse pendant mise en contact des particules de charbon avec ledit mélange polymérisable est du mazout n° 2.
14. Procédé selon l'une quelconque des revendications 1 à 9, caractérisé en ce qu'on soumet les particules de charbon enrichi récupérées en tant que produit dans l'opération e) à un traitement supplémentaire dans un milieu aqueux avec un acide gras saturé et on les neutralise éventuellement avec un métal alcalin ou alcalino-terreux, ou autre agent de neutralisation contenant un métal.
15. Procédé selon la revendication 14, caractérisé en ce que l'acide saturé est de l'acide naphténique.
16. Mélange charbon-huile transportable constitué par des particules d'un produit de charbon hydrophobe et oléophile enrichi obtenu par un procédé selon l'une quelconque des revendications 1 à 15 dispersé dans un hydrocarbure liquide porteur.
17. Mélange charbon-huile selon la revendication 16 contenant des particules de charbon enrichi obtenues par le procédé selon la revendication 12, c'est-à-dire par neutralisation de groupes acide carboxylique présents sur la surface des particules de charbon et résultant de l'utilisation d'un monomère contenant un acide carboxylique, caractérisé en ce qu'on opère la neutralisation après dispersion des particules de charbon enrichi dans l'hydrocarbure porteur.
18. Mélange charbon-eau transportable constitué par des particules d'un charbon hydrophobe et oléophile enrichi obtenues par un procédé selon l'une quelconque des revendications 1 à 13 dispersées dans un liquide aqueux porteur.
19. Mélange charbon-eau selon la revendication 18, caractérisé en ce que les particules enrichies ont été obtenues en utilisant un monomère contenant un acide carboxylique, les groupes carboxyliques présents sur la surface des particules enrichies ayant été ultérieurement neutralisées par un métal alcalin.
EP19810300152 1980-01-22 1981-01-14 Procédé d'amélioration du charbon et charbon ainsi amélioré Expired EP0032811B1 (fr)

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AT81300152T ATE12790T1 (de) 1980-01-22 1981-01-14 Verfahren zur aufbereitung von kohle und aufbereitetes kohleprodukt.

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US06/114,357 US4332593A (en) 1980-01-22 1980-01-22 Process for beneficiating coal
US114357 1980-01-22
US114414 1980-01-22
US06/114,414 US4304573A (en) 1980-01-22 1980-01-22 Process of beneficiating coal and product

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EP0032811B1 true EP0032811B1 (fr) 1985-04-17

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1668097A2 (fr) * 2003-08-29 2006-06-14 Richard C. Holmes Systeme et procede pour superviser la production de combustible synthetique

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US4306883A (en) * 1981-01-29 1981-12-22 Gulf & Western Manufacturing Company Process for forming coal-oil mixtures under selected conditions of temperature and shear
AU551442B2 (en) * 1981-01-29 1986-05-01 Gulf & Western Industries Inc. Benefication of coal
DE3562627D1 (en) * 1985-10-23 1988-06-16 Standard Oil Co Ohio Method for the beneficiation of low rank coal and products obtained thereby
SE509025C2 (sv) * 1995-01-23 1998-11-30 Bycosin Ab Ämne för tillsättning till fasta biobränslen
WO2009115933A1 (fr) * 2008-03-17 2009-09-24 Chuluun Enkhbold Procédé de valorisation et de transport de matières minérales
WO2015128923A1 (fr) 2014-02-25 2015-09-03 株式会社アクト Procédé de fabrication d'une substance combustible séchée et substance combustible séchée ainsi obtenue
CN112973952A (zh) * 2021-03-30 2021-06-18 中国矿业大学 一种井下煤炭液固流态化分选系统及工艺
CN113372973B (zh) * 2021-07-26 2024-06-04 重庆四季金标科技有限公司 燃煤火电厂用防水煤粉及其利用系统以及深度调峰方法

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US2913349A (en) * 1956-12-18 1959-11-17 Standard Oil Co Coal spray composition
US4033852A (en) * 1975-06-26 1977-07-05 Polygulf Associates Process for treating coal and products produced thereby
US4101293A (en) * 1977-03-30 1978-07-18 Reichhold Chemicals, Inc. Stabilizing emulsifiers
AT370763B (de) * 1977-05-31 1983-05-10 Scaniainventor Ab Kohlensuspension, enthaltend pulverisierte kohle, wasser und dispergierungsmittel, sowie verfahren zur herstellung derselben

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1668097A2 (fr) * 2003-08-29 2006-06-14 Richard C. Holmes Systeme et procede pour superviser la production de combustible synthetique
EP1668097A4 (fr) * 2003-08-29 2008-08-20 Richard C Holmes Systeme et procede pour superviser la production de combustible synthetique

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DE3169930D1 (en) 1985-05-23
PL136658B1 (en) 1986-03-31
GB2068410A (en) 1981-08-12
EP0032811A2 (fr) 1981-07-29
PL142354B1 (en) 1987-10-31
EP0032811A3 (en) 1981-10-14
PL229301A1 (fr) 1981-09-18

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