EP0197164A1 - Process for beneficiating coal employing low amounts of additives - Google Patents

Process for beneficiating coal employing low amounts of additives Download PDF

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Publication number
EP0197164A1
EP0197164A1 EP85103961A EP85103961A EP0197164A1 EP 0197164 A1 EP0197164 A1 EP 0197164A1 EP 85103961 A EP85103961 A EP 85103961A EP 85103961 A EP85103961 A EP 85103961A EP 0197164 A1 EP0197164 A1 EP 0197164A1
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EP
European Patent Office
Prior art keywords
coal
polymerizable monomer
weight
water
fluid organic
Prior art date
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.)
Withdrawn
Application number
EP85103961A
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German (de)
English (en)
French (fr)
Inventor
Philipp E. Mcgarry
David E . Herman
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Standard Oil Co
Original Assignee
Standard Oil Co
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Filing date
Publication date
Priority to ZA852350A priority Critical patent/ZA852350B/xx
Application filed by Standard Oil Co filed Critical Standard Oil Co
Priority to EP85103961A priority patent/EP0197164A1/en
Publication of EP0197164A1 publication Critical patent/EP0197164A1/en
Withdrawn legal-status Critical Current

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    • 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
    • B03D1/001—Flotation agents
    • B03D1/004—Organic compounds
    • B03D1/016—Macromolecular compounds
    • 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
    • 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 OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
    • 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
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/001—Flotation agents
    • B03D1/004—Organic compounds
    • B03D1/008—Organic compounds containing oxygen
    • 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
    • B03D2201/00—Specified effects produced by the flotation agents
    • B03D2201/04—Frothers
    • 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
    • B03D2203/00—Specified materials treated by the flotation agents; Specified applications
    • B03D2203/02—Ores
    • B03D2203/04—Non-sulfide ores
    • B03D2203/08—Coal ores, fly ash or soot

Definitions

  • coal Regardless, however, of the form in which the coal is ultimately employed, the coal must be cleaned because it contains substantial amounts of sulfur and nitrogen compounds and mineral matter, including significant quantities of metal impurities. During combustion, these materials enter the environment as sulfur dioxides, nitrogen oxides and compounds of metal impurities. If coal is to be accepted as a primary energy source, it must be cleaned to prevent pollution of the environment, either by cleaning the combustion products or the coal prior to burning.
  • chemical coal cleaning techniques are in a very early stage of development.
  • Known chemical coal cleaning techniques include, for example, oxidative desulfurization of coal (sulfur is converted to a water-soluble form by air oxidation), ferric salt leaching (oxidation of pyritic sulfur with ferric sulfate), and hydrogen peroxide sulfuric acid leaching.
  • Other methods are also disclosed in the above- noted reference to the Encyclopedia of Chemical Technology, Volume 6, pages 314-322.
  • raw coal is first cleaned of rock and/or other extraneous materials as may be required and then pulverized, preferably in the presence of water, to a relatively fine average particle size.
  • An aqueous slurry of the finely pulverized coal is contacted with a polymerization reaction medium comprising a polymerizable monomer and polymerization catalyst therefor, and a fluid organic medium such as a distillate fuel for dispersing the coal and the polymerization reaction medium.
  • a polymerization reaction medium comprising a polymerizable monomer and polymerization catalyst therefor
  • a fluid organic medium such as a distillate fuel for dispersing the coal and the polymerization reaction medium.
  • the surface-treated coal particles are readily separated from unwanted ash and sulfur-containing components which are present in the aqueous component of the slurry. Moreover, the hydrophobic coal can be readily further dehydrated to very low water levels without employing costly thermal energy.
  • the clean, very low moisture content coal resulting from this process can theh be employed as is, i.e., as a dry solid product, or further processed to advantageous coal-oil or coal-aqueous mixtures.
  • the present invention provides a process for beneficiating coal which comprises:
  • the sole figure is a flow diagram of a coal beneficiating process according to an embodiment of the invention herein.
  • coal in pulverized form is combined with water, polymerization reaction medium and a fluid organic medium which facilitates contact of the surface of the coal particles with the reaction medium.
  • the average particle size of the coal can vary widely with finer particle sizes rendering the impurities present in the coal more accessible to removal.
  • the advantage of conducting the process upon very fine particle size coal can, however, be offset by the cost of the additional energy required to achieve such particle size.
  • a particle size of from about 48 to about 200 mesh (Tyler Standard screen size) or greater will provide acceptable results with a reasonable expenditure of energy. So far as is known, there is no objection if a larger percentage of the coal is smaller than 200 mesh but it is preferred if no large percentage is much above the 48 mesh size.
  • the coal After leaving the size reduction operation, the coal can be screened to remove particles exceeding 48 mesh which are then returned for further size reduction.
  • Reduction of the raw coal can be carried out in the absence of added liquid but for convenience is preferably carried out in the presence of water.
  • a water treating agent include dispersants, surfactants, wetting agents and the like.
  • Preferred water conditioning additives are sodium carbonate, sodium pyrophosphate and the like. It may also be further advantageous to employ water which has previously been treated in an ion exchange technique.
  • the quantity of water in admixture with the coal can vary over wide limits provided a sufficient amount is ultimately present to result in an apparent aqueous phase and an apparent flocculent phase containing surface-treated coal particles as more fully described hereinafter. It is generally preferred to employ only as much water as is necessary to provide the aforesaid phases in order to minimize the overall amount of water which must be processed. In contrast to prior art beneficiation processes which typically are carried out upon coal slurries containing from about 90% to about 95% water by weight, the present process works very well with slurries containing from about 65% to about 95% water by weight.
  • such monomers include ethylene, propylene, butylene, tetrapropylene, isoprene, 1,3-butadiene, pentadiene, dicyclopentadiene, octadiene, olefinic petroleum fractions, styrene, vinyltoluene, vinylchloride, vinylbromide, 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, or salts thereof, particularly those included within the formula wherein R is an olefinically unsaturated organic radical, preferably containing from about 2 to about 30 carbon atoms, and R' is hydrogen, a salt-forming cation such as an alkali metal, alkaline earth metal or ammonium cation, or a saturated or ethylenically unsaturated hydrocarbyl radical, preferably containing from 1 to about 30 carbon atoms, either unsubstituted or substituted with one or more halogen atoms, carboxylic acid groups, hydroxyl groups and/or hydroxyl groups in which the hydroxyl hydrogens may be replaced with saturated and/or unsaturated acyl groups, the latter preferably containing from about 8 to about 30 carbon atoms.
  • R is an olefinically unsaturated organic radical, preferably containing from about 2 to about 30 carbon atoms
  • R' is hydrogen
  • Specific monomers conforming to the foregoing structural formula include unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, rincinoleic acid, mono-, di- and tri-glycerides of one or more unsaturated fatty acids, and other esters of unsaturated fatty acids, acrylic acid, methacrylic acid, methylacrylate, ethylacrylate, ethylhexylacrylate, tertiary-butylacrylate, oleylacrylate, methylmethacrylate, oleylmethacrylate, stearylacrylate, stearylmethacrylate, laurylmethacrylate, vinylstearate, vinylmyristate, vinyl- laurate, soybean oil, cottonseed oil, palm oil, dehydrated castor oils, tall oil, corn oil, and the like. For the purpose of this invention tall oil and corn oil have been found to provide particularly advantageous results. Corn oil is especially preferred.
  • the monomer can be used at a level of from about .005% to about .10%, and preferably, 0.1% to about .05%,by weight of dry coal.
  • the catalyst employed in the polymerization reaction medium can be selected from among any such materials commonly used to effect polymerization of ethylenically unsaturated monomers. Typically, for the purposes of this invention, a catalytic amount of those catalysts of the so-called free radical type are preferred. Their amounts include from about 10-1000 ppm of catalyst, preferably 10-200 p pm (parts per million) based on the amount of dry coal.
  • catalysts contemplated herein include benzoyl peroxide, methylethyl ketone peroxide, tertbutylhydroperoxide, hydrogen peroxide, ammonium persulfate, di-tert-butylperoxide, tert-butyl- perbenzoate, peracetic acid, and including such non- peroxy free radical initiators as the diazo compounds, such as 1-1-bis-azo-isobutyro nitrile and the like. Hydrogen peroxide is especially preferred for use herein.
  • free radical polymerization systems commonly employ free radical initiators which function to initiate the formation of free radicals.
  • any of the initiators disclosed in the prior art can be used.
  • some of these initiators include, for example, sodium perchlorate and perborate, sodium persulfate, potassium persulfate, ammonium persulfate, silver nitrate, water soluble salts of noble metals such as platinum and gold, water soluble salts of iron, zinc, arsenic, antimony, tin and cadmium.
  • Particularly preferred initiators herein are the water soluble copper salts, i..e., cuprous and cupric salts, such as copper acetate, copper sulfate and copper nitrate.
  • initiators contemplated herein are also disclosed in U.S. Patent Application Serial No. 230,063 filed January 29, 1981. These initiators include metal salts of naphthenates, tallates, octanoates, etc., said metals including copper, cobalt, chromium, mercury, manganese, nickel, tin, lead, zinc, iron, rare earth metals and mixed rare earths. Amounts of initiator contemplated for use herein are generally in the range from about 10-1000 ppm (parts per million) of the metal portion and preferably 10-200 ppm, based on the amount of dry coal.
  • the catalyst shall be present in any catalytically effective amount.
  • Optimum quantities employed will depend upon such factors as the nature and concentration'of the monomer, the pressure and temperature under which polymerization occurs, the reaction rate desired, and so forth, and can be determined for a particular beneficiation process employing simple procedures as is evident to those skilled in the art.
  • Ambient pressure will ordinarily be used for reasons of process economy and simplicity and for the same reasons, ambient temperatures or slightly higher will also be favored although it is, of course, recognized that polymerization will readily occur within a broad temperature range, e.g. from about 0°C to about 200°C.
  • hydrogen peroxide can be used as catalyst at a level of from about 0.01% to about 0.1% by weight of dry coal with good results,
  • Fluid organic media included within the scope of this invention are for example, fuel oil, such as No. 2 or No. 6 fuel oils, other hydrocarbons including benzene, toluene, xylene, hydrocarbons-fractions such as naphtha and medium boiling petroleum fractions (boiling point 100°-180°C), dimethylformamide, tetrahydrofuran, tetrahydrofurfuryl alcohol, dimethylsulfoxide, methanol, ethanol, isopropyl alcohol, acetone, methylethylketone, ethylacetate, and the like, and mixtures thereof.
  • fuel oil such as No. 2 or No. 6 fuel oils
  • other hydrocarbons including benzene, toluene, xylene hydrocarbons-fractions such as naphtha and medium boiling petroleum fractions (boiling point 100°-180°C)
  • dimethylformamide tetrahydrofuran
  • tetrahydrofurfuryl alcohol dimethyl
  • fuel oil is a preferred fluid organic medium.
  • the maximum amount of fluid organic medium which can be used herein represents a critical aspect of the present invention and, in combination with polymerizable monomer, must not exceed 2.0% by weight of the coal being processed. By itself, it is preferred to use from about 0.10 % to about 1.0%, and more preferred, from about 0.20% to about 0.50% fluid organic medium by weight of coal.
  • the frothing agents which are optionally intended for use herein can be selected from among any of the known and conventional materials used to effect frothing in coal which are suitable for use herein include aliphatic alcohols such as methylisobutyl carbinol (MIBC) which is a preferred frothing agent herein, the cresylic acids, eucalptus oils, camphor oils and pine oils, all of which are slightly soluble in water.
  • MIBC methylisobutyl carbinol
  • Water soluble frothers which can be used herein include alkyl ethers and phenyl ethers of propylene and polypropylene glycols.
  • the amount of optional frothing agent employed will depend in large measure upon the volume of slurry undergoing treatment and the coal content thereof and is related to other process parameters as will be readily understood by those skilled in the art. Amounts of frothing agent ranging from about 0.005% to about 0.5% or higher, and preferably from about 0.01% to abo ⁇ t 0.1%, by weight of dry coal being treated generally provide good results. The point of addition is not critical; however, to avoid the possibility that frothing might interfere with the surface treating phase of the coal cleaning process, it is preferred to add the frothing agent to the slurry only after significant polymerization has taken place, i.e., from about 1 minute to about 2 hours following contact of the coal with the polymerization reaction medium.
  • the process herein contemplates conventional flotation recovery techniques, intermittent or continuous skimming of the surface-treated coal from the surface of the slurry being an entirely suitable technique.
  • the recovered coal flocculate can, if desired, be subjected to one or more further cycles of chemical surface treatment and/or washing to effect still greater separation of impurities and/or recovery of treated pulverized coal.
  • a particularly effective technique for separating the treated coal particles from unwanted ash and sulfur in the water phase is an aeration spray technique wherein a coal froth phase is formed by spraying or injecting the treated coal-water slurry into the surface of cleaning water as is described and claimed in U.S. Patent Nos. 4,347,126 and 4,347,127 incorporated herein by reference.
  • the coal slurry is injected through at least one spray nozzle at pressures for example at from about 15-20 psi to a spaced-apart distance above the water surface into the water surface producing aeration and a frothing or foaming of the coal particles, causing these particles to float to the water surface for skimming off.
  • raw coal entering through line 16 is cleaned of unwanted rock, heavy ash and the like and is crushed in the presence of water,added through line 18, in pulverization zone 10 to provide an aqueous coal slurry.
  • the rock and ash leave pulverization zone 10 through line 20.
  • the particulate coal in the slurry is ground to particle sizes of about 48 to 300 mesh, preferably about 80% of the particles being of about a 200 mesh size.
  • a water conditioning agent such as described hereinbefore may also be added through line 22 to assist in the separation of impurities.
  • the aqueous coal slurry is fed to a chemical and separation zone 12 through line 24 where it is admixed with fuel oil and polymerizable monomer such as corn oil introduced through line 26.
  • the fuel oil can act as a diluent for the monomer.
  • Polymerization catalyst such as hydrogen peroxide and free radical initiator such as cupric nitrate are also added to zone 12 via line 28 and admixed therein.
  • the reactants, coal- aqueous slurry and carrier oil are sprayed into at least one froth flotation vessel (not shown) in zone 12 wherein a coal froth phase and an aqueous impurity containing phase ensue.
  • frothing agent is also added to the slurry in zone 12 through line 30 to induce frothing.
  • the aqueous impurity containing phase containing ash and sulfur is removed through line 32 and may be sent to, e.g., waste disposal treatment.
  • the coal froth phase containing cleaned coal. particles, is removed such as by skimming or otherwise and recovered through line 34.
  • the recovered coal which may be dried can be used as is, such as for example in the formation of coal-oil or coal-aqueous mixtures or may be used as a particulate coal for burning.
  • a series of coal beneficiating runs were carried out upon Pittsburgh Seam coal at varying levels of polymerizable monomer (i.e., corn oil) and fluid organic medium (i.e., No. 2 fuel oil) to demonstrate the improved levels of ash reduction and moisture reduction obtained at relatively low levels of combined monomer and fluid organic medium.
  • polymerizable monomer i.e., corn oil
  • fluid organic medium i.e., No. 2 fuel oil

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Liquid Carbonaceous Fuels (AREA)
EP85103961A 1985-03-28 1985-04-02 Process for beneficiating coal employing low amounts of additives Withdrawn EP0197164A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
ZA852350A ZA852350B (enrdf_load_stackoverflow) 1985-03-28 1985-03-28
EP85103961A EP0197164A1 (en) 1985-03-28 1985-04-02 Process for beneficiating coal employing low amounts of additives

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA852350A ZA852350B (enrdf_load_stackoverflow) 1985-03-28 1985-03-28
EP85103961A EP0197164A1 (en) 1985-03-28 1985-04-02 Process for beneficiating coal employing low amounts of additives

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EP0197164A1 true EP0197164A1 (en) 1986-10-15

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EP85103961A Withdrawn EP0197164A1 (en) 1985-03-28 1985-04-02 Process for beneficiating coal employing low amounts of additives

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ZA (1) ZA852350B (enrdf_load_stackoverflow)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0057577A2 (en) * 1981-01-29 1982-08-11 The Standard Oil Company Method for the beneficiation, liquefaction and recovery of coal and other solid carbonaceous materials and beneficiated coal products
EP0066066A2 (en) * 1981-05-28 1982-12-08 The Standard Oil Company Beneficiated coal, coal mixtures and processes for the production thereof and an arrangement for producing a beneficiated coal product
US4450070A (en) * 1981-11-13 1984-05-22 The Dow Chemical Company Imidazoline conditioner for the flotation of oxidized coal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0057577A2 (en) * 1981-01-29 1982-08-11 The Standard Oil Company Method for the beneficiation, liquefaction and recovery of coal and other solid carbonaceous materials and beneficiated coal products
EP0066066A2 (en) * 1981-05-28 1982-12-08 The Standard Oil Company Beneficiated coal, coal mixtures and processes for the production thereof and an arrangement for producing a beneficiated coal product
US4450070A (en) * 1981-11-13 1984-05-22 The Dow Chemical Company Imidazoline conditioner for the flotation of oxidized coal

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Publication number Publication date
ZA852350B (enrdf_load_stackoverflow) 1985-11-26

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