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WO2010028459A1 - Réduction directe - Google Patents

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Publication number
WO2010028459A1
WO2010028459A1 PCT/AU2009/001217 AU2009001217W WO2010028459A1 WO 2010028459 A1 WO2010028459 A1 WO 2010028459A1 AU 2009001217 W AU2009001217 W AU 2009001217W WO 2010028459 A1 WO2010028459 A1 WO 2010028459A1
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WO
WIPO (PCT)
Prior art keywords
gas
fluidised bed
process according
feed
metal oxide
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/AU2009/001217
Other languages
English (en)
Inventor
John David Winter
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.)
Austpac Resources NL
Original Assignee
Austpac Resources 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
Priority claimed from AU2008904808A external-priority patent/AU2008904808A0/en
Application filed by Austpac Resources NL filed Critical Austpac Resources NL
Publication of WO2010028459A1 publication Critical patent/WO2010028459A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/12—Dry methods smelting of sulfides or formation of mattes by gases
    • C22B5/14—Dry methods smelting of sulfides or formation of mattes by gases fluidised material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B11/00—Making pig-iron other than in blast furnaces
    • C21B11/02—Making pig-iron other than in blast furnaces in low shaft furnaces or shaft furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0046—Making spongy iron or liquid steel, by direct processes making metallised agglomerates or iron oxide
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/02—Making spongy iron or liquid steel, by direct processes in shaft furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B15/00—Other processes for the manufacture of iron from iron compounds
    • C21B15/006—By a chloride process
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
    • F27B15/02—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B15/10—Arrangements of air or gas supply devices
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
    • C21B2100/20—Increasing the gas reduction potential of recycled exhaust gases
    • C21B2100/28—Increasing the gas reduction potential of recycled exhaust gases by separation
    • C21B2100/282—Increasing the gas reduction potential of recycled exhaust gases by separation of carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
    • C21B2100/40—Gas purification of exhaust gases to be recirculated or used in other metallurgical processes
    • C21B2100/44—Removing particles, e.g. by scrubbing, dedusting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
    • C21B2100/60—Process control or energy utilisation in the manufacture of iron or steel
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
    • C21B2100/60—Process control or energy utilisation in the manufacture of iron or steel
    • C21B2100/64—Controlling the physical properties of the gas, e.g. pressure or temperature
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B2200/00—Recycling of non-gaseous waste material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C2100/00—Exhaust gas
    • C21C2100/06—Energy from waste gas used in other processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
    • Y02P10/122—Reduction of greenhouse gas [GHG] emissions by capturing or storing CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
    • Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a method and apparatus for the direct reduction of metal oxides to metals and in particular the direct reduction of iron (DRI).
  • DRI direct reduction of iron
  • the present invention aims to provide an alternative direct reduction arrangement which overcomes or ameliorates the disadvantages of the prior art, or at least provides a useful choice.
  • the invention provides a process for the direct reduction of a metal oxide to a metal within a single stage fluidised bed reactor.
  • the process includes the steps of: feeding to a single stage fluidised bed the metal oxide and reactants for production of a reductant gas, then production of the reductant gas, contacting the metal oxide with the reductant gas to reduce it to a metal.
  • the process includes controlling a rate of reaction of the gasification and/or reduction by control of one or more of a CO 2 concentration or a H 2 O concentration of the reactor where tHe CO 2 and/or H 2 O concentrations may be controlled in a feed gas to the fluidised bed reactor.
  • the feed gas for CO 2 and/or H 2 O concentration control or adjustment is derived from a recycled off-gas discharged from the fluidised bed.
  • a gasification rate of reaction may be controlled by introduction of a controlled amount of steam.
  • further control may be had with the delivery to the fluidised bed of reactants such as fuel, air and oxygen.
  • the reactants for production of a reductant gas include a carbonaceous fuel and a reactant gas.
  • the carbonaceous fuel may be selected from the group consisting of coal, oil, natural gas and hydrocarbon fuels, whilst the reactant gas may be air and/or oxygen.
  • the metal is iron or is predominantly iron and the metal oxide an iron oxide.
  • the metal oxides may be obtained from iron ore, metallic oxide wastes or metal chloride wastes.
  • the metal oxide may be obtained from wastes such as mill scales, baghouse dusts, blast furnaces, electric arc furnaces, galvanising processes or zinc contaminated iron processes.
  • the production of the reductant gas is conducted in a base region of the fluidised bed with the reduction of the metal oxide being conducted in an intermediate region of the fluidised bed. Furthermore incompletely reduced metal oxide is retained in the intermediate region of the fluidised bed until reduced due to the reduced metal having a lower density than the metal oxide and any incompletely reduced metal oxide. Once the metal oxide is reduced to the metal product it is transported to an overflow region of the fluidised bed.
  • the present invention provides a single stage fluid bed apparatus and method for direct reduction of a metal oxide to metal, said single stage including production of a reductant gas, and reduction of the metal oxide by the reductant gas.
  • Preferred aspects of the invention include:
  • the recycled off-gas is treated to reduce the CO 2 and/or H 2 O concentrations; • Controlling or modifying the reaction kinetics by adjusting the CO 2 and/or H 2 O concentrations of the recycled off- gas.
  • the fluid bed apparatus configuration includes a fluid bed reaction chamber which increases in transverse cross-section from a feed end to a discharge end;
  • the invention provides a single stage fluidised bed reactor for direct reduction of a metal oxide to a metal product.
  • the reactor comprises: a support for a fluidised bed, a metal oxide feed to the fluidised bed, one or more reactant feeds for feeding reactants for production of a reductant gas within the fluidised bed.
  • the production and presentation of reductant gas to the metal oxide produces the metal product within the fluidised bed.
  • Metal product may then be discharged from an upper portion of the fluidised bed.
  • the fluidised bed in the fluidised bed reactor increases in cross-sectional area from the base portion to the upper portion by 20% to 40%.
  • a taper angle of a wall of the fluidised bed reactor, between the base portion and the upper portion of the fluidised bed is in the range of 1° to 15°.
  • the reactor includes a distributor for the feeding of the reactant gases to the fluidised bed and for supporting and maintaining the fluidisation.
  • the distributor feeds a recycled off-gas feed and a reactant gas feed.
  • the reactor also includes a CO 2 removal apparatus for at least partial CO 2 removal from the off-gas being recycled.
  • the reactor may also include a H 2 O removal apparatus for at least partial H 2 O removal from the off-gas being recycled.
  • the reactant gas feed is introduced to the fluidised bed above the level of the recycled off-gas feed into the fluidised bed.
  • the reactant gas feed is directed generally downwardly toward the off-gas feed which is directed generally horizontally.
  • the distributor may comprises: a reactant gas feed with a conical protuberance that at its apex has a reactant gas aperture formed with a corresponding conical cap to the conical protuberance and an off-gas feed comprising one or more tuyeres (other suitable feed syn-gas apertures) located in an annular arrangement about the base of the conical protuberance.
  • FIG. 1 is a flowchart of a process according to one embodiment of the invention.
  • FIG. 2 is a schematic cross-section elevation of a fluid bed reactor according to a further embodiment of the invention.
  • FIG. 3 is a detailed schematic of the bottom of the fluidised bed reactor of FIG 2.
  • FIG 4 is an alternate embodiment of FIG 1.
  • FIG 5 is an alternate embodiment of FIG 3.
  • FIG 6 is a plan view of the transverse section along the lines 6-6 of FIG 5.
  • FIG 1 is a flowchart of a continuous process to directly reduce a metal oxide to a metal, according to a first embodiment. While the process is shown here as a stand-alone process, it may also be combined with other operations as part of another process, for example a steel making facility, or processing of metal chloride solutions such as described in the Applicant's patent application WO 06/133500 "Processing of Metal Chloride Solutions and Method and Apparatus for Producing Direct Reduced Iron", the contents of which are incorporated herein by reference.
  • FIG. 1 a gasification and metallisation vessel ("G&M vessel")
  • fluidised bed 112 contains a single, continuous fluidised bed 112. Within the fluidised bed 112 gasification to produce a reductant gas with direct reduction metallisation of the metal oxide by the reductant gas are both undertaken.
  • Gasification to produce a reductant gas may be achieved within the G&M vessel 110 using a feed of either a solid, liquid or gaseous carbonaceous or hydrocarbon fuel as appropriate to local availability and cost structures.
  • Suitable fuels that may be converted to a reducing gas include coal, oil or natural gas.
  • Common terms that may be used for reductant gases of this general type include synthetic gas (“syn gas”), water gas, producer gas and the like. The term "syn gas" is used herein.
  • the oxygen for these reactions may be supplied either as ambient or preheated air and with or without oxygen enrichment.
  • the aim is to ensure that only sufficient oxygen is used to provide enough heat of combustion to maintain the endothermic reactions that generate the CO and H 2 components necessary for the metal oxide reduction reactions occurring simultaneously. For example, it has been found that satisfactory results may be obtained with a substoichiometric oxygen supply of between 30% to 50% of the full stoichiometric combustion requirement.
  • the reactants for gasification are added to the single stage fluidised bed 112 as coal 114 in a preferred particle size range of 2 to 12 mm, air 116 pre-heated to less than 950 0 C or more preferably to a temperature range of 300° to 700 0 C or 400° to 700 0 C and recycled, modified syn gas 122 in a preferred temperature range of 800° to 1000 0 C.
  • the reductant gas formed by the gasification reaction is supplemented with a feed of modified, recycled off-gas from the reactor discharge, as will be described in more detail later.
  • the metal oxide 118 for reduction is introduced into the single stage fluidised bed 112.
  • a Fe 2 O 3 particulate feedstock 118 of a preferred particle size range of 0.5 to 4 mm - preferably pre-heated using waste heat to between 800 and 1000 0 C, and more preferably approximately 900 0 C, may be used.
  • the Fe 2 O 3 feedstock 118 may be iron ore, metallic oxide wastes such as mill scales and baghouse dusts, waste from zinc contaminated iron processes, wastes from blast and electric arc furnaces or derived from part of another process such as described in patent application WO 06/133500 "Processing of Metal Chloride Solutions and Method and Apparatus for Producing Direct Reduced Iron".
  • the metal oxide 118 is fluidised by the gases and initially reduced by contact with the reductant gases, in the case of the present example iron (III) oxide, into an oxide of lower valence, Fe(II), without metallising. It is important that the initial reduction takes place rapidly so that the formation of FeO is predominant and the formation of the intermediate oxide Fe 3 O 4 is minimised; as too high a proportion OfFe 3 O 4 may lead to incipient fusion and/or a critical amount of accretion resulting in a consequent collapse of the fluidised bed 112 and/or the accretion OfFe 3 O 4 onto the reactor vessel 110 internal surfaces.
  • the design and construction to minimise incipient fusion and accretion within the G&M vessel 110 and the fluidised bed 112 is described below with respect to FIG 2.
  • the inventor has further noted that within the fluidised bed 112 that the presence of the FeO may also act as a catalyst for the gasification reactions described here.
  • the fluidised bed 112 for the reduction and gasification steps is maintained in a temperature range of 750° to 105O 0 C or in a preferred temperature range of 870 ° to 92O 0 C with a most preferred temperature of approximately 900 0 C.
  • the pressure within the G&M vessel 110 may be approximately atmospheric or just above as required to sustain process flows, for example nominally about 20-40 kPa above the atmospheric pressure.
  • HBI hot briquetted iron
  • the Fe(s) product may be indirectly cooled under such conditions as to exclude air and so avoid any reoxidation of the product which could occur whilst the material is at an elevated temperature. Nominally, the metallised pellets will be cooled to less than 200° C or lower before contact with air is allowed.
  • reaction rate of the reductions described here may be controlled by adjusting the rates and composition of the fuel 114, air 116 and/or syn gas 122 feeds to the reactor such that the off gas 120 composition from the fluidised bed 112 is according to the equation:
  • K>0.7 is preferred in order for the reduction reactions to proceed at an appropriate speed within the fluidised bed 112.
  • K is approximately 0.9, to obtain a relatively rapid reduction of the metal oxide and hence a low mean residence time in the order 20 minutes, up to 60 minutes at lower K ⁇ 0.7, for completion of the reduction reaction.
  • the rate of reaction may thus be controlled by modifying the concentrations of CO 2 and H 2 O, with the rate of reaction increasing as the concentrations of CO 2 and/or H 2 O decrease.
  • these concentrations may be controlled by adjustment of the composition of the modified off-gas recycled back to the reactor as syn gas, and/or the amount of the recycled syn gas relative to the fuel and air feed.
  • FIG 1 illustrates one method for treatment of the off-gas 120 CO 2 and/or H 2 O concentrations to produce a modified syn gas 122 for recycle feed back to the fluidised bed 112, in order to achieve the desired reaction rate for the reductions.
  • a part 121 of the off-gas 120 discharge from the top of the fluidised bed 112 is split off and fed through a heat exchanger 124 that is used to preheat the modified syn gas 122 that is supplied to the fluidised bed 112.
  • the remaining or excess portion 136 of the off gas 120 is fed to an afterburner 140 where it is combusted with combustion air 138.
  • the hot combustion gases 142 then being fed to a heat exchanger 144 for further heating of the syn gas feed 122.
  • the spent waste gases 146 from heat exchanger 144 may then be piped away for waste heat recovery.
  • the cooled off-gas 123 is fed into a H 2 O removal system 126 to adjust the concentration of H 2 O in the off-gas 128.
  • the H 2 O removal apparatus 126 may be of a type known per se, for example the use of cooling water 133 to condense (or quench) H 2 O as a condensate 134 from the off gas 128 or other appropriate system or arrangement for dehumidifying the off-gas 120.
  • the H 2 O removal apparatus is operated so as to lower the H 2 O content from about 7 % in the off gas 120, 123 to about 1% v/v (volume / volume) in the syn gas feed 128, 122, such that preferably about 85% of the moisture present in the off-gas 120 is removed.
  • a removal system (not shown) for sulphur compounds.
  • the sulphur removal system may be of a type known per se, for example a caustic (NaOH) scrubber, or other appropriate system or arrangement for removing sulphur from the off-gas.
  • the dehumidified off-gas 128 may then be fed into CO 2 removal apparatus 130 to reduce the concentration of CO 2 in the off-gas 128.
  • the CO 2 removal apparatus 130 may be of a type known per se, for example a monoethanolamine (MEA) scrubber or other appropriate system or arrangement for reducing the CO 2 of the off-gas.
  • MEA monoethanolamine
  • the CO 2 removal apparatus is operated so as to lower the CO 2 content from about 8% down to about 1% v/v, such that preferably about 90%, of the CO 2 present in the off-gas 120 is removed 131.
  • the CO 2 and H 2 O concentrations of the reactor feed gases may be controlled so as to control the reaction rate/s described above.
  • Means for controlling the CO 2 and H 2 O concentrations include (i) varying the operation of the CO 2 and H 2 O removal apparatuses 130,126 to modify the amount of CO 2 and H 2 O removed, (ii) treating a variable proportion of the off-gas 120 using the CO 2 and H 2 O removal apparatus, and then optionally blending the treated and untreated off-gases prior to or at the feed to the reactor; or (iii) varying the amount of recycled off-gas fed back to the reactor 110.
  • FIG 1 also illustrates an example of how the heat balance within the fluidised bed 112 varies in conjunction with (iii) above. As the proportion of off- gas 120 bled off to the recycle stream 121 is varied, the remaining or excess off gas 136 combusted with combustion air 138 in the afterburner 140 to produce hot combustion gases 142 also varies, and thus the amount of the hot combustion gases 142 to the second heat exchanger 144.
  • the relative proportions of the various reactants, with air and syn gas expressed in m 3 /h at standard temperature and pressure (STP) and coal 114 and iron oxide feed are in units of kg/h, all per kg/h of coal feed, may be approximately: air 116 : recycled, modified off gas 122 : coal 114 : Fe 2 O 3 feed 118
  • iron oxide is derived from the pyrohydrolysis step of WO 06/133500 as described earlier:
  • FIG. 2 illustrates a fluid bed reactor arrangement 110 according to a second embodiment of the invention.
  • the reactor 110 is upright and generally cylindrical, with a refractory lining 214 forming a generally frusto-conical reaction chamber defined by tapered side walls 210, which contain the fluidised bed 112.
  • the feed apparatus for the respective reactants feed to the bottom of the fluidised bed - the metal oxide feedstock 118 via a metal oxide inlet tube 216, coal or other fuel 114 via a fuel inlet tube 218, and air 116 and recycled and modified syn gas 122 via a distributor arrangement 222 which will be described in more detail later with reference to FIG. 3.
  • the reactor 110 further includes a bed drain discharge 224 communicating with the reaction chamber at the base of the fluid bed 112, for removal of large particles and purging of the reactor 110. There may also be an overflow removal port / metal product discharge 226 for removal of the DRI product 132, and an off-gas discharge 120 at the top of the reactor vessel 110.
  • the inlet tubes 216 and 218 for the solid reactants are preferably angled down through the side wall of the reaction chamber 110 to a location near the base of the fluidised bed 112, just above the distributor 222.
  • the metal oxide 118 and coal 114 feeds may be fed by gravity or pneumatically assisted into the reaction chamber, or by any other suitable means.
  • the solid material feeds enter the reaction chamber adjacent the gas inlets via the distributor, in a manner to facilitate initial mixing of the reactants.
  • the recycled, modified syn gas 122 and air 116 are fed via the distributor 222 into the bottom of the fluidised bed, causing fluidisation of the bed 112.
  • the gaseous and solid reactants both move upwards through the reactor, although there will at any time be a proportion of particles within the fluidised bed which are moving counter to this.
  • the gasification and initial stage reduction reactions occur predominantly at the bottom / base portion of the fluidised bed, any transient formation OfFe 3 O 4 occurring at an intermediate height within the bed, and the reduction of FeO to Fe metal occurring mostly in the upper portion of the bed.
  • the outward taper 212 of the reaction chamber side walls 210 is designed to provide an increase in the transverse (in the example of FIG. 2, horizontal) cross sectional area of the fluidised bed 112 between the bottom of the fluidised bed 112 adjacent the feeds 114, 118, 222 and the top of the chamber adjacent the metal discharge 132.
  • the increase in transverse cross-sectional area being in the order of 20- 40%, preferably about 30%, to accommodate a reduction in particle density of the metal oxide feedstock as it is reduced to the metal.
  • the taper angle 212 of the side wall may be dependent for example on the bulk flow rate up through the reactor and desired residence time, but may for example be in the range of 1-15 degrees, more preferably about 5-10 degrees.
  • the process achieves faster gas velocities at the base of the fluidised bed where the reactants are being fed and mixed initially, and then a lowering in mean gas velocity reduces as the reaction progresses and travels up through the fluidised bed, due to the increasing reactor cross-sectional area of the fluidised bed.
  • the appropriate fluidising velocities, varying with bed depth, for the various stages of the reactions corresponding to changes in particle density are maintained through the depth of the fluidised bed.
  • Waste heat from the process for example from cooling of the
  • FIG. 3 is a detail of the bottom / base region of the fluidised bed reactor 112, showing the air 116 and recycled syn gas 122 inlets via distributor 222.
  • the distributor 222 is situated adjacent the bottom of the reactor
  • the distributor 222 is itself constructed so as to form an internal air plenum 318 which receives and distributes air 116 from an air or oxygen supply tube 220 to a series of air flow passages 310 in a top refractory layer 314 of the plate.
  • This construction allows the modified off gas / syn gas 122 and the air 116 feeds to be kept separate and contacted only within the fluidised bed, where they are contacted with the coal 114 and metal oxide 118 particles.
  • the alternating rings or other patterns of the air apertures 310 and syn gas apertures 312 and relatively high gas inlet velocities facilitate mixing at the bottom of the fluidised bed 112 as well as the fluidising of the bed 112.
  • the number arrangement and size of the air and syn gas inlets in the distributor 222 may be varied according to geometry and feed materials of the particular reactor.
  • FIG 4 is an alternate embodiment of the continuous metal reduction process of FIG 1.
  • the alternate G&M vessel 410 features an adaption to mix oxygen 417 with the air 116 for injection 415 into the base region of the fluidized bed 412 as described in detail with respect to FIG 5.
  • Oxygen 417 may be mixed with the air 116 to enrich the oxygen content delivered to the fluidized bed up to approximately 30%, or more preferably in the range of 25% to 50% v/v (volume/volume).
  • the enrichment of the oxygen content has the benefit of lowering the nitrogen content in the process as well as improved reaction and fuel values with the fuel 114 and metal oxide 118.
  • 50% to 100% oxygen 417 concentration may be mixed with the air 116.
  • the fluidised bed 412 At 100% oxygen concentration therefore, no air is fed to the fluidised bed..
  • steam water vapour
  • the addition of the steam 419 is to compensate for the increased temperatures that may result from the use of high oxygen 417 concentrations, the consequences of which are described below with respect to FIGs 5 and 6 below.
  • the steam 419 may quench or otherwise reduce temperatures at the base of the fluidised bed 412 by the thermal mass of the steam and/or the steam (H 2 O) entering into endothermic gasification reactions (e.g. the water shift reaction, given earlier) with the additional advantage of extra H 2 being generated within the fluidised bed 412.
  • the oxygen 417 and air 116 gas mix may be delivered with no preheating, that is an ambient temperature gas in contrast to the preheating used with respect to the embodiment of FIG 1.
  • the steam 419 may be mixed into the gas injection stream 415 as appropriate to maintain the vapour phase of the steam. It will be readily appreciated that the gas mix injection 415 is as appropriate to maintain the fluidisation of the fluidised bed 412.
  • the process of FIG 4 also features a single heat exchanger and a bag house filter as well as other differences which are described in the following.
  • Off- gas 120 from the alternate G&M vessel 410 is fed into a heat exchanger 424 which is used to pre-heat the modified off-gas / syn gas 422 prior to its injection into the fluidised bed 412.
  • the cooled off-gas 423 from the heat exchanger 424 may then be temperature controlled to a constant temperature between 120° to 200 0 C by suitable direct injection of water 448 into the gas stream of the off-gas 423.
  • the level of water injection 448 is always below water saturation for the off-gas 423 together with the temperature of the off-gas 423 being always above the dew point prior to entry into the bag house filter 450.
  • the bag house filter 450 may be used to remove fine particulates 451 from the off-gas 423
  • the bag house 450 may be substituted with any other suitable filter as selected by a person skilled in the art, for example micro-pore ceramic filters.
  • the fine particulates removed 451 may include carbon complexes and volatile metal oxides.
  • the particulate metal oxides may result from volatile metals liberated in the fluidised bed 412 which are then oxidised in some manner to result in fine particulates within the off-gas 120.
  • Zinc may be an example of one such volatile metal which may be generated when a feedstock 118 derived from zinc-iron-chloride solutions is used.
  • Zinc-iron-chloride solutions may be typically associated with galvanising processes,
  • the filtered off-gas 452 may then be fed to the respective H 2 O
  • H 2 O and/or CO 2 modified off-gas / syn gas 422 may then be pre-heated by heat exchanger 424 as described above and then injected into the fluidised bed 412.
  • Excess off-gas 436 may be dealt with in a similar manner to that of FIG 1.
  • the excess off-gas 436 may be removed from the recycled off-gas stream after the bag house filtration 450.
  • the excess off-gas 436 may then be combusted with combustion air 138 in an afterburner 140, the hot waste gas 142, 146 being then utilised in waste heat recovery as required.
  • the relative proportions of the various reactants, with air, oxygen and syn gas expressed in m 3 /h at standard temperature and pressure (STP) and coal 114 and iron oxide feed are in units of kg/h, all per kg/h of coal feed, may be approximately:
  • FIG 5 is a distributor 522 in an alternate embodiment of that shown in FIGs 2 and 3. Like numbers have been used to denote like features between FIG 5 and those of FIGs 2 and 3. Air 116 and/or oxygen 417 are supplied by the tube 220 that emerges from an apex of a cone 554 of the alternate distributor 522. A cone cap 556 at the apex of the cone 554 redirects the air 116 and/or oxygen 417 gas streams in the formed aperture 310 mostly downwards, as shown by the undulating arrows, into the base region of the fluidised bed and towards the syn gas tuyeres 558.
  • the syngas tuyeres 558 contain apertures 312 which are orientated so as to project the syn gas / modified, recycled off-gas 122, 422 mostly horizontally, as shown by the respective undulating arrows.
  • the syngas tuyeres 558 are attached to an annular plate 560 of the alternate distributor 522. Items such as the refractory layer 314 have been omitted for clarity.
  • FIG 6 is a plan view of the alternate distributor 522 along the sectional line of 6-6 in FIG 5.
  • FIG 6 in particular illustrates the flow of the air 116, oxygen 417 and syn gas 122, 422 gas streams from the top of the distributor 522 and into the bottom or base region of the fluidised bed 112, 412, as shown by the respective undulating arrows.
  • the configuration of the alternate distributor 522 allows any agglomerates / accretions which may form in the vicinity of the air/oxygen apertures 310 to sink in the fluidised bed, due to their higher specific gravity, to the base of the fluidised bed where conditions are not favourable to further agglomeration / accretion and where reactions to reduction of the metal oxide may proceed more favourably.
  • One example of the start-up of the above process may be by: (i) Initial heating of a bed of iron ore within the G&M vessel 110, 410 by gas burner, then feeding in coal 114 and air 116 under full oxidative conditions to reach a desired high bed temperature.
  • the present invention in its preferred forms thus provides a continuous, single stage process for direct reduction of iron or other metals, which it is believed will overcome or ameliorate at least some of the problems of the prior art, such as complexity and capital cost, and operational problems such as those caused by the formation of a 'sticky' Fe 3 O 4 phase (or other agglomerating / accretion prone contaminants or metal oxide phases), higher pressures for operation, multiple stages and their inherent multiple material transfer systems.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Dispersion Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
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Abstract

La présente invention concerne un procédé et un appareil permettant de réduire directement en métaux des oxydes de métaux. Ce procédé met en œuvre une gazéification et métallisation (410) à l'intérieur d'un lit fluidisé à étage unique (412). Du combustible carboné (114) et une masse d'oxyde de métal (118) peuvent être fluidisés, avec, à la base du lit fluidisé (412), de l'air (116), un enrichissement en oxygène (417), et de la vapeur (419). En outre, le dégagement gazeux (120) provenant de la gazéification et de la métallisation peut subir un ajustement portant sur la teneur en H2O et CO2, avant d'être introduit dans le lit fluidisé (412) sous forme de gaz de synthèse (422) destiné à la régulation du traitement de gazéification et de métallisation. Le produit métallique résultant est recueilli (132) sur le dessus du lit fluidisé (412). L'invention concerne également des appareils et des moyens permettant d'obtenir et d'entretenir la fluidisation pour que la gazéification et la métallisation (410) puissent intervenir.
PCT/AU2009/001217 2008-09-15 2009-09-15 Réduction directe Ceased WO2010028459A1 (fr)

Applications Claiming Priority (2)

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AU2008904808A AU2008904808A0 (en) 2008-09-15 Direct Reduction
AU2008904808 2008-09-15

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WO2010028459A1 true WO2010028459A1 (fr) 2010-03-18

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023194194A1 (fr) * 2022-04-08 2023-10-12 thyssenkrupp Polysius GmbH Système et procédé de traitement thermique d'un matériau minéral
BE1030435B1 (de) * 2022-04-08 2023-11-14 Thyssenkrupp Ind Solutions Ag Anlage und ein Verfahren zur Wärmebehandlung von mineralischem Material

Citations (7)

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Publication number Priority date Publication date Assignee Title
US4082545A (en) * 1975-08-05 1978-04-04 Istituto Di Ricerca Finsider Per La Riduzione Diretta S.P.A. Reduction of iron ore in fluidized bed reactors
US4260412A (en) * 1980-01-16 1981-04-07 Midrex Corporation Method of producing direct reduced iron with fluid bed coal gasification
US5064467A (en) * 1987-11-02 1991-11-12 C.V.G. Siderurgica Del Orinoco, C.A. Method and apparatus for the direct reduction of iron
US5527379A (en) * 1993-06-19 1996-06-18 Metallgesellschaft Aktiengesellschaft Process for a direct reduction of iron oxide containing materials to form Fe3 C
US5858057A (en) * 1996-09-25 1999-01-12 Hylsa S.A. De C.V. Method for producing direct reduced iron with a controlled amount of carbon
US6027545A (en) * 1998-02-20 2000-02-22 Hylsa, S.A. De C.V. Method and apparatus for producing direct reduced iron with improved reducing gas utilization
US6039916A (en) * 1996-09-25 2000-03-21 Hylsa S.A. De C.V. Apparatus for producing direct reduced iron with a controlled amount of carbon

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4082545A (en) * 1975-08-05 1978-04-04 Istituto Di Ricerca Finsider Per La Riduzione Diretta S.P.A. Reduction of iron ore in fluidized bed reactors
US4260412A (en) * 1980-01-16 1981-04-07 Midrex Corporation Method of producing direct reduced iron with fluid bed coal gasification
US5064467A (en) * 1987-11-02 1991-11-12 C.V.G. Siderurgica Del Orinoco, C.A. Method and apparatus for the direct reduction of iron
US5527379A (en) * 1993-06-19 1996-06-18 Metallgesellschaft Aktiengesellschaft Process for a direct reduction of iron oxide containing materials to form Fe3 C
US5858057A (en) * 1996-09-25 1999-01-12 Hylsa S.A. De C.V. Method for producing direct reduced iron with a controlled amount of carbon
US6039916A (en) * 1996-09-25 2000-03-21 Hylsa S.A. De C.V. Apparatus for producing direct reduced iron with a controlled amount of carbon
US6027545A (en) * 1998-02-20 2000-02-22 Hylsa, S.A. De C.V. Method and apparatus for producing direct reduced iron with improved reducing gas utilization

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023194194A1 (fr) * 2022-04-08 2023-10-12 thyssenkrupp Polysius GmbH Système et procédé de traitement thermique d'un matériau minéral
BE1030435B1 (de) * 2022-04-08 2023-11-14 Thyssenkrupp Ind Solutions Ag Anlage und ein Verfahren zur Wärmebehandlung von mineralischem Material

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