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WO1998027186A1 - Procede de traitement de charbon - Google Patents

Procede de traitement de charbon Download PDF

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Publication number
WO1998027186A1
WO1998027186A1 PCT/AU1997/000838 AU9700838W WO9827186A1 WO 1998027186 A1 WO1998027186 A1 WO 1998027186A1 AU 9700838 W AU9700838 W AU 9700838W WO 9827186 A1 WO9827186 A1 WO 9827186A1
Authority
WO
WIPO (PCT)
Prior art keywords
coal
coal particles
treatment
particles
tailings
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.)
Ceased
Application number
PCT/AU1997/000838
Other languages
English (en)
Inventor
Jeremey James Lees
Murray Howard Pryor
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Minpro Australia NL
Original Assignee
Minpro Australia NL
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Minpro Australia NL filed Critical Minpro Australia NL
Priority to AU53945/98A priority Critical patent/AU5394598A/en
Publication of WO1998027186A1 publication Critical patent/WO1998027186A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • 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
    • C10L5/00—Solid fuels
    • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
    • C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
    • C10L5/08—Methods of shaping, e.g. pelletizing or briquetting without the aid of extraneous binders

Definitions

  • the present invention relates generally to the recovery of clean coal from coal tailings and in particular to the production of useful coal product from coal fines.
  • Solid carbonaceous materials such as coal
  • coal have long been employed as a fuel source whether it be by simple combustion or conversion into a gaseous or liquid fuel.
  • Certain coals when suitably processed into coke also provide an essential raw material in iron making.
  • coals contain mineral particulates to some degree. Excessive levels of such mineral particulates are undesirable as they interfere with the combustion of the coal and the formation of coke. The particulates also lead to undesirable increases in ash levels during processing and combustion.
  • Prior to utilisation most coals have traditionally undergone a washing treatment. During such a treatment, finely divided coal or coal fines of varying sizes are washed into the waste water together with the mineral particulates and other gangue materials. These coal tailings are typically held in settling ponds on the mine site. In addition to representing a loss of coal, the disposal of the waste water can represent an environmental hazard.
  • the present invention consists in a process for the treatment of coal tailings containing coal particles, comprising the steps of:
  • the present invention consists in a process for the treatment of coal tailings containing coal particles, comprising the steps of: (i) forming a slurry containing the coal particles;
  • the present invention consists in a process for the treatment of coal tailings containing coal particles, comprising the steps of:
  • the coal particles undergo a heat treatment process.
  • the heat treatment may be undertaken in any suitable vessel or retort adapted for the purpose including a tube, pipe, cyclone, or rotary furnace or reactor.
  • the coal particles Prior to undergoing the heat treatment, the coal particles are preferably dried in a predryer to remove any water present after the earlier processing steps.
  • the heat treatment vessel is preferably hermetically connected to the predryer to allow the dried coal particles to be moved into the vessel following drying without exposure to water vapour in the atmosphere.
  • the coal particles are preferably heated to a plastic state with the minimum temperature being about 350°C. Any volatile liquids or combustible gases liberated from the coal during the heat treatment process can be recycled and used to heat the coal particles in the heat treatment process.
  • the agglomerating step preferably comprises a mechanical means of agglomerating the plasticised coal particles.
  • the agglomeration can comprise extruding the plasticised coal particles, for example, by using a pellet mill.
  • Other possible agglomerating techniques include forming agglomerates by tumbling, vibrating, shaking or paddle mixing the plasticised coal particles.
  • a pelletising pan, rotary drum agglomerator, or fluidised bed can also be utilised in the agglomerating step.
  • the coal particles are preferably cooled in a cooling device that would be typically hermetically connected to the agglomerating means.
  • the cooler would preferably bring the temperature of the agglomerated coal product below the temperature at which the product would ignite on exposure to air, and recover waste heat.
  • the further heat treatments can include a multi-stage heat treatment process.
  • This multistage process can include an initial heat treatment at a temperature of at least 200 C to recover semi-coke products and further heat treatments at higher temperatures to recover coke product.
  • the further heat treatment steps could occur at temperatures up to around 1200°C.
  • the step of treating the coal slurry to obtain the coal particles that will then undergo the heat treatment step can be undertaken by any suitable means.
  • the coal particles can be separated and recovered from gangue materials on the basis of the size, specific gravity, electrical behaviour, magnetic behaviour or chemical behaviour of the coal particles in comparison to the remaining constituents of the tailings.
  • the separation of the coal particles that will undergo the heat treatment step from the remaining coal particles can also be undertaken by any suitable means including separation on the basis of size and specific gravity of the particles.
  • the treatment step can include a specific gravity separation step.
  • This step is preferably adapted to recover coal particles having dimensions between around 1.7mm to around 75 microns.
  • This step may be performed by one or more spiral separators or classifiers.
  • the spiral separators may be replaced by teeter bed separators or similar suitable gravity separation devices.
  • a spiral separator a number of helical sluices are mounted about a single vertical column below a slurry feed box. The slurry in its descent on each sluice tends to stratify with the denser fraction of the minerals moving towards the axis of the separator and the less dense materials being carried to the outer part of the sluice.
  • the separated fractions are recovered in separate outlets at the lower end of the separator.
  • the treatment step further includes at least one sieve screen deck over which is passed the slurry of coal particles.
  • the sieve screen deck can be rapped or vibrated as needs dictate.
  • the slot aperture of the deck will be set to a size as required by the application and could vary between individual sieve screen decks in the treatment process.
  • the treatment step can include a screening drum mounted substantially vertically as described in International Patent Application No PCT/AU97/00003, the contents of which are incorporated herein by reference.
  • Another means of treating the coal tailings could comprise or include a cyclone separation zone comprising, preferably, at least two cyclone stages in series.
  • the cyclone separation zone would preferably be used as a treatment step of the coal slurry prior to it entering a froth flotation process described below.
  • the treatment step could include a froth flotation process where a coal slurry is aerated in an aeration vessel in which the coal particles attach to the air bubbles and rise while the gangue particles fall towards the bottom of the vessel.
  • the rising air bubbles with the coal particles attached produce a froth product that may overflow the aeration vessel and be recovered or may be separated by conventional means such as froth scrapers or paddles.
  • the froth flotation step when combined with a cyclone separation zone having two cyclone separation zones in series as described above, would preferably substantially remove from the slurry coal particles having dimensions in the range less than about 150-200 microns to 75-100 microns.
  • two or more aeration vessels may be utilised in series to ensure good recovery of the coal particles from the slurry.
  • Fig. 1 is a flow chart of one embodiment of the invention.
  • Fig. 2 is a flow diagram of one preferred embodiment of the tailings treatment step in the process depicted in Fig. 1.
  • Preferred Mode of Carrying out the Invention A flow chart of one embodiment of the process according to the present invention is generally depicted as 10 in Figvire 1.
  • a coal slurry which may have been dredged from a coal tailings pond, is fed through an initial treatment step 11 to remove coal particles of sizes greater than around 75 microns from the slurry.
  • an initial treatment step 11 One possible embodiment of the processes that may be performed at step 11 is depicted in Fig. 2.
  • the coal slurry in treatment step 11 is firstly fed over a screen 100 to remove all particles greater than 1.7mm that are recovered and processed as required.
  • the water and particles of less than 1.7mm are fed into a sump 101 where the slurry pulp density is adjusted to between 10-30% by weight solids, preferably 24%, and pumped by pump 102 into a hydrocyclone 103 that has an included cone angle of 15°.
  • Oversized particles and smaller dense particles form the underflow having a pulp density of from 40-60% while the generally smaller particles and larger less dense particles form the overflow which is fed to a s ⁇ mp 104 forming part of a secondary treatment circuit.
  • the underflow from the hydrocyclone 103 is repulped to a density of 20-50%, preferably 25%, and fed over a rapped or vibrated sieve screen deck 105 that has a radius of about 1.9 metres, an arc angle of about 35° and a slot aperture of about 380 microns.
  • the water and fines tend to flow throLigh the screen 105 to produce an underflow that flows into sump 104.
  • the particles having a size above about 250 microns will form an overflow from the sieve screen 105 having a pulp density of about 40-60%.
  • the underflow from the hydrocyclone 103 is generally of larger particles, it is contaminated with a proportion of smaller and denser particles that would normally end up in the final coal product stream and raise its gangue content.
  • the overflow stream from the sieve screen deck 105 thus comprises coal particles and gangue having a particle size from approximately 250 microns to 1.7mm.
  • the overflow stream from the sieve screen deck 105 is repulped in sump 106 to a pulp density of 20% and pumped by pump 107 to a bank of spiral separators 108 where the particles are separated by density into a product stream and a reject stream.
  • the product stream is fed to a further bank of spiral separators 109 to clean the product stream and to produce a final product stream and a reject stream.
  • the reject streams from spiral separators 108 and 109 are combined and then conveyed by sump 110 and pump 111 to the froth flotation vessel 12 (see Fig. 1).
  • the final product stream from spiral separators 109 is dewatered on a sieve screen deck 112 similar to sieve screen deck 105 and the overflow is fed either directly or indirectly to product storage for later processing.
  • the underflows from sieve screen deck 112 are directed to sump 104 where they join the underflows from the hydrocyclone 103 and the sieve screen deck 105.
  • the sump 104 feeds a fine particle separation circuit through pump
  • the pump 113 feeds a slurry of pulp density of about 25% to a hydrocyclone 114 of a smaller included cone angle than hydrocyclone 103.
  • the overflow from hydrocyclone 114 is fed to sump 110 while the underflow having a pulp density of about 50% is repulped to 20% and fed over sieve screen deck 114a similar to sieve screen deck 105 except that the gap width is about 100 microns.
  • the underflow from sieve screen deck 114a is fed to sump 110 while the overflow containing particles of greater than about 75 microns is fed to a sump 115 where it is repulped and fed by pump 116 to a bank of spiral separators 117.
  • the product stream from spiral separators 117 is fed to cleaning spiral separator 118.
  • the reject stream from each of these separators is fed to sump 110 while the final product stream from spiral separator 118, which has a majority of coal particles having sizes between about 75 microns and 250 microns, is fed to a dewatering sieve screen deck similar to deck 114 where the coal particles of greater than about 75 microns are recovered and further processed as required.
  • a hydrocyclone similar to the hydrocyclones 103 and 114 may precede each of the dewatering sieve screen decks.
  • the slurry from sump 110 which predominantly should contain particles less than 75 microns in size is then fed via a feed pipe into a second treatment step 12.
  • the treatment step 12 comprises a froth flotation vessel in which air and coal particles are fed into the vessel.
  • the coal particles preferentially attach to the air bubbles that rise upwardly in the flotation agent in the vessel, normally an aqueous solution, to form a froth product that is scaped from the top of the vessel using a scraper blade.
  • the coal particles are then washed and filtered from the froth product ready for further processing.
  • the gangue particles introduced into the vessel settle downwardly in the vessel and can be recovered from the bottom of the vessel as desired.
  • the slurry of coal particles recovered from the treatment step 12 are then mixed in a mixer, generally depicted as 13, with the coal particles recovered from the final product stream of spiral separator 118 in treatment step 11.
  • the mixture of particles is then fed into a predryer unit 14 which sufficiently heats the unit to vaporise any water.
  • Hermetically connected to the predryer unit 14 is a heat treatment vessel 15 into which the coal particles are moved following drying in the predryer unit 14.
  • the coal particles are heated to a temperature sufficient to plasticise the coal, namely at least 350°C. Any volatiles liberated from the coal during this heat treatment process can be recycled and used to provide energy for the heating of the coal made in vessel 15.
  • the plasticised coal is then processed in a pellet mill 16 that agglomerates the plasticised coal and extrudes it into agglomerates conveniently sized for further handling.
  • agglomerators could be employed including a pLig mill, a pelletising pan, a rotary drum agglomerator or a fluidised bed.
  • the agglomerates are then passed through a cooler unit 17 that is also hermetically connected to the pellet mill 16.
  • the cooler unit 17 brings the temperature of the coal product below a temperature at which it would ignite if exposed to air.
  • the cooled coal agglomerates 18 produced by the process 10 can be further processed as required, the further processing including further heat treatment steps.
  • the process 10 provides a means of removing coal particles having a range of dimensions in an efficient manner from a slurry of coal tailings and converting the recovered coal particles into a commercially useful and more easily handled product.
  • the heat treatment step also desirably produces a chemical change in the coal, with the coal product 18 having a lower level of volatiles, an increase in fixed carbon, and an increase in specific heat value in comparison to the coal fines present in the tailings dam.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)

Abstract

L'invention concerne un procédé destiné à la récupération de particules de charbon à partir de résidus de charbon, qui consiste à traiter tout d'abord les résidus de charbon afin de séparer une partie des particules de charbon présentant des dimensions comprises dans une gamme spécifiée; et à soumettre ensuite les particules de charbon à un traitement thermique, puis à une agglomération en vue de produire un produit de charbon. Le procédé prévoit un moyen supplémentaire de récupération de particules de charbon de petites dimensions à partir de boues.
PCT/AU1997/000838 1996-12-18 1997-12-09 Procede de traitement de charbon Ceased WO1998027186A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU53945/98A AU5394598A (en) 1996-12-18 1997-12-09 Coal processing method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPO4297A AUPO429796A0 (en) 1996-12-18 1996-12-18 Coal processing method
AUPO4297 1996-12-18

Publications (1)

Publication Number Publication Date
WO1998027186A1 true WO1998027186A1 (fr) 1998-06-25

Family

ID=3798605

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1997/000838 Ceased WO1998027186A1 (fr) 1996-12-18 1997-12-09 Procede de traitement de charbon

Country Status (2)

Country Link
AU (1) AUPO429796A0 (fr)
WO (1) WO1998027186A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3073751A (en) * 1960-08-01 1963-01-15 Consolidation Coal Co Method of making formcoke
US3401089A (en) * 1965-03-03 1968-09-10 Consolidation Coal Co Process for agglomerating carbonaceous materials
US3562783A (en) * 1966-03-28 1971-02-09 Consolidation Coal Co Process for making agglomerates from coal using coal extract as binder
US4133718A (en) * 1976-05-17 1979-01-09 Dravo Corporation Method for agglomerating finely divided agglomerative materials in a rotary drum assembly
EP0082470A2 (fr) * 1981-12-18 1983-06-29 Hitachi, Ltd. Procédé pour l'amélioration de charbon de qualité inférieure
WO1991011502A1 (fr) * 1990-01-24 1991-08-08 Alberta Research Council Valorisation du charbon et du petrole par un procede de microagglomeration et de bouletage thermique (procede 'comat')

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3073751A (en) * 1960-08-01 1963-01-15 Consolidation Coal Co Method of making formcoke
US3401089A (en) * 1965-03-03 1968-09-10 Consolidation Coal Co Process for agglomerating carbonaceous materials
US3562783A (en) * 1966-03-28 1971-02-09 Consolidation Coal Co Process for making agglomerates from coal using coal extract as binder
US4133718A (en) * 1976-05-17 1979-01-09 Dravo Corporation Method for agglomerating finely divided agglomerative materials in a rotary drum assembly
EP0082470A2 (fr) * 1981-12-18 1983-06-29 Hitachi, Ltd. Procédé pour l'amélioration de charbon de qualité inférieure
WO1991011502A1 (fr) * 1990-01-24 1991-08-08 Alberta Research Council Valorisation du charbon et du petrole par un procede de microagglomeration et de bouletage thermique (procede 'comat')

Also Published As

Publication number Publication date
AUPO429796A0 (en) 1997-01-23

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