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WO2004007775A2 - Production directe de metaux et d'alliages affines - Google Patents

Production directe de metaux et d'alliages affines Download PDF

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Publication number
WO2004007775A2
WO2004007775A2 PCT/GB2003/003065 GB0303065W WO2004007775A2 WO 2004007775 A2 WO2004007775 A2 WO 2004007775A2 GB 0303065 W GB0303065 W GB 0303065W WO 2004007775 A2 WO2004007775 A2 WO 2004007775A2
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WO
WIPO (PCT)
Prior art keywords
hearth
carrier material
loop
zone
refining
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/GB2003/003065
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English (en)
Other versions
WO2004007775A3 (fr
Inventor
Noel Alfred Warner
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Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to EP03764006A priority Critical patent/EP1521851A2/fr
Priority to AU2003254456A priority patent/AU2003254456A1/en
Priority to US10/521,306 priority patent/US20060162498A1/en
Publication of WO2004007775A2 publication Critical patent/WO2004007775A2/fr
Publication of WO2004007775A3 publication Critical patent/WO2004007775A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces
    • F27B3/04—Hearth-type furnaces, e.g. of reverberatory type; Electric arc furnaces ; Tank furnaces of multiple-hearth type; of multiple-chamber type; Combinations of hearth-type 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
    • C21B13/0006—Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0073—Selection or treatment of the reducing gases
    • 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • 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
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/56—Manufacture of steel by other methods
    • C21C5/567—Manufacture of steel by other methods operating in a continuous way
    • 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
    • C22B23/00—Obtaining nickel or cobalt
    • C22B23/02—Obtaining nickel or cobalt by dry processes
    • C22B23/021—Obtaining nickel or cobalt by dry processes by reduction in solid state, e.g. by segregation processes
    • 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
    • C22B23/00—Obtaining nickel or cobalt
    • C22B23/06—Refining
    • 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
    • C22B34/00—Obtaining refractory metals
    • C22B34/30—Obtaining chromium, molybdenum or tungsten
    • C22B34/32—Obtaining chromium
    • 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
    • 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
    • C21B2100/62—Energy conversion other than by heat exchange, e.g. by use of exhaust gas in energy production
    • 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
    • C21B2100/66—Heat exchange
    • 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
    • Y02P10/25—Process efficiency

Definitions

  • This invention relates to thermal reduction of metal oxide materials, for example iron oxide ores such as haematite, metal oxide ores, e.g. nickel -laterite and chromite ores, and deepsea manganese nodules, for the purpose of recovering metallic values therefrom in a refined condition on a continuous basis.
  • metal oxide materials for example iron oxide ores such as haematite, metal oxide ores, e.g. nickel -laterite and chromite ores, and deepsea manganese nodules.
  • the present invention is also concerned with the treatment of steel plant fines, in-plant fines and other secondary materials generated during metallurgical and waste incineration operations.
  • a method for recovery of metals from oxide materials is disclosed in EP 0266975 and US 4701217, in which smelting reduction of metallic oxide materials, e.g. pelletised iron oxide ore or iron ore fines is effected by contacting such material with a circulating molten carrier material, e.g. molten iron in the case of iron oxide smelting, in a furnace, and by introducing a carbonaceous reductant e.g. coal into the carrier material.
  • the reductant converts the metal oxide to metal, which is assimilated immediately into the molten carrier material in a smelting reduction zone.
  • Carbon monoxide thereby produced is combusted in a heating zone through which the carrier material passes to effect heat recovery. Slag is removed from the carrier material before entering the heating zone.
  • a protective layer of molten material, e.g. lead, which is substantially stationary is maintained below the circulating carrier material to inhibit erosion of the furnace hearth.
  • EP 0266975 and US 4701217 also make reference to laboratory testwork in which cylindrical compacts of mixed pulverised coal and haematite ore fines were immersed in a liquid metal heat transfer medium (lead) for two minutes. Below 900°C very little reaction occurred, whereas at 1300°C metallisations as measured by bromine-methanol dissolution were in the range 85-90%. It was suggested that if the composite pellets were immersed in hot metal (molten iron containing dissolved carbon) even faster rates could be expected. These observations were not actually made use of in the processes discussed in these former patents but now they are germane to the present invention.
  • a circulating molten carrier can be advantageous not only in an improved method for reduction of oxide of certain metal oxides but also to recover on a continuous basis refined metal or alloy therefrom in preparation for continuous casting or other downstream finishing operations, e.g. ingot casting, fragmentation, globulation, granulation or if a powered product is required, atomisation.
  • a method of reducing metal oxide material to metal comprising the steps of forcibly circulating molten carrier material in a closed loop path serially through a charge reduction zone on one arm of the loop, a combined melt desulphurisation zone and post combustion or heating zone on the other; reducing said metal oxide to solid metal by the carbonaceous material contained within a mixed composite charge of the metal oxide, carbonaceous reductant and flux in said reduction zone, the metal oxide and carbonaceous reductant being utilised in proportions such that the carbon from the carbonaceous reductant is converted to carbon monoxide; reacting the carbon monoxide with oxygen in the refining loops downstream from the reduction loop before being combusted to completion in the heating zone at the surface of the molten carrier material so that heat generated by the reaction is transferred to the molten carrier material which is circulated to the reduction zone; separating a metallised raft from said molten carrier material by projecting said metallised raft along into the first refining loop by virtue of the drag force
  • the molten carrier material is not involved chemically to a major extent in the reduction process but is there to transport the charge and reaction product materials in the solid state at elevated temperature through an extended path in contact with the molten carrier material which provides the endothermic heat requirements for chemical reactions to take place within a layer of composite charge material, deposited across the width of the molten carrier material near to one end of the charge arm.
  • a chemical reaction front moves through the layer commencing with solid material submerged in the molten carrier material on the underneath side of the deposited layer, possibly involving an initial formation of solidified crust of the molten carrier material when the charge materials are first deposited at the feed end and then as heat is conducted into the layer, the reaction front progressively moves upward through the layer as it floats away along the arm on the molten carrier material, all the time releasing coal volatiles and gaseous products of reduction into the gas space above the layer which is enclosed by walls and a roof of thermal insulating material.
  • Conduction within agglomerated materials is the principal heat transfer means even at very high temperatures and in the present case this is enhanced by metal not originally in the charge materials infiltrating into the charge layer as production progresses to enhance that produced by reduction. Also sintering phenomena which result ultimately in the formation of a metallised raft emerging from the far end of the arm cause a progressive increase in thermal conductivity the longer the material stays floating down the metallisation arm of the reduction loop. Direct contact with liquid metal eliminates the need for radiative heat transfer in the metallisation arm so there is no special requirement to provide geometric arrangements that ensure access to direct thermal radiation as this is no longer an issue as it is with current technology.
  • the capillary rise effect occurs as a consequence of hot metal wetting the newly-formed solid metal as a result of gas phase reactions and being drawn into the porous structure by surface tension. From capillary theory, the rise is directly proportional to the surface tension and inversely proportional to the density of the liquid, so this means that for molten iron the propensity for capillary rise is more than twice as great as that for water entering a porous solid material, assuming that the degree of wetting as measured by the so-called contact angle is the same in both cases.
  • the infiltration of hot metal by the capillary rise phenomenon as reduction proceeds effectively reduces the thermal resistance between the molten carrier material and the progressively upwards moving reduction zone to such an extent that heat transfer influences are very considerably reduced so that the kinetics of the chemical reactions become all important, a situation under the control of the process designer in so far as the chemical kinetics can be regulated by specifying particle size of the reacting solids. This means that the most cost-effective solution can be identified for a particular case.
  • the gas freeboard distance above the solids may be arranged so that local gas velocities are consistent with the propensity for solids entrainment.
  • the gas velocity has to be relatively low in the charging region with progressive increase permissible as the solids sinter or agglomerate partially, a condition achieved, for example, by profiling the cross-section of the furnace gas space.
  • the metallised raft projected out of the reduction loop is comprised of residual solid metal formed by gaseous reduction, which has not yet had the opportunity to be assimilated into the molten carrier material, in association with slag constituents and excess coke coal all forming an agglomerated solid structure.
  • an increased amount of molten carrier material clearly has to be overflown along with the metallised raft to the steelmaking loop in order to balance any new metal being added to the molten carrier material in the reduction loop itself.
  • the mixed charge to the charge arm of the reducing loop is comprised principally of carbonaceous material, metal oxide material and usually a suitable flux, e.g. lime, limestone or dolomite with particle size requirements determined by preliminary laboratory testing.
  • a suitable flux e.g. lime, limestone or dolomite with particle size requirements determined by preliminary laboratory testing.
  • simple mechanical mixing of the constituents will be all that is required.
  • the method of the present invention is usually performed with a very large proportion of molten carrier material circulation to metal produced.
  • a circulation ratio of 100:1 to 500:1 can be employed in the ironmaking loop, the actual ratio depending upon the nature of the feed and the energy requirements thereof.
  • a circulation ratio of 315:1 is employed, namely for every unit of iron produced, 315 units of molten iron as carrier are circulated between the reduction zone and the heating zone in the closed loop path.
  • the rate of circulation depends upon the size of the equipment and the required reduction rate.
  • the metal oxide material incorporated within the composite mixed charge, which forms the layer floating on the molten carrier material, is subjected to reduction to produce the metal, and carbon monoxide is evolved above the surface of the molten carrier material and is preferably passed to the other treatment stages which may optionally include liquid metal based hot gas clean-up or other means of desulphurisation; boosting in pressure; staged partial combustion with oxygen to facilitate melting of the metallised raft and combustion of excess carbon therein; liquid slag formation; and decarburisation of the molten carrier material in at least one (preferably two) downstream melt circulation loops by top blowing and direct flame impingement mechanisms, before being passed to the heating zone of the reduction loop where combustion to carbon dioxide is finally completed.
  • the other treatment stages which may optionally include liquid metal based hot gas clean-up or other means of desulphurisation; boosting in pressure; staged partial combustion with oxygen to facilitate melting of the metallised raft and combustion of excess carbon therein; liquid slag formation; and decarburisation of the molten carrier material
  • the temperature of the molten carrier material depends upon the type of metal oxide being reduced and is chosen to ensure that the carrier material is prevented from solidifying.
  • the temperature is typically about 1300°C, which is high enough to promote reduction but not high enough to cause melting of the solids in the floating charge layer.
  • the proportions of metal oxide to carbonaceous reductant depend again upon the metal oxide being reduced and also open the nature of the carbonaceous reductant. However, the proportions employed will be such as to given carbon monoxide. Thus, it will be usual to operate the process with stoichiometric excess of carbon relative to the amount of oxide to be reduced.
  • overflows or is siphoned into at least one further melt circulation loop to effect additional refining and composition adjustment after which the molten metal continuously discharges either by overflowing or by siphonic removal so that it either becomes the product refined metal or alloy or optionally continues on for further refining eg. in a packed tower for countercurrent contacting with argon or other suitable gas under reduced pressure to reduce impurities to ultra-low levels.
  • the metallised raft comprised of solid metal, unreacted carbon, gangue oxide constituents possibly already reacted to form solid slag compounds and solid fluxes to further aid liquid slag formation and metal refining, is propelled out of the charge arm of the reduction loop into the metallised raft melting and slag formation/separation arm of .the first in-line refining loops, utilising the resultant drag force exerted on the raft by the molten carrier material in the charge arm of the reduction loop and possibly assisted by maintaining a shallow depth of molten carrier material on the cross-over interconnecting the two said melt circulation loops to ensure unimpeded continuous transference of the metallised raft onto the surface of a second molten carrier material being circulated in a closed loop path serially through a top blown/flame impingement zone in order to melt the metallised raft, burn excess carbon on one arm of the loop and a second arm on which heating and additional refining processes such as desulphurisation and decarburisation
  • Separation of slag and metal occurs by the solid metal in the metallised raft being assimilated into the molten carrier material and the slag forming a continuous molten layer floating on the molten carrier material down to the far end from the feed input where it either overflows with the molten carrier material into a downstream zone where slag can accumulate for intermittent tapping while the molten carrier material is removed from beneath the accumulated slag for continuous circulation to the other arm of the melt circulation loop using a gas-lift mechanism or siphon, whichever is the more appropriate.
  • the overflow weir can be dispensed with and use made of an electromagnetic dam as developed for continuous strip casting and the like to keep the molten metal back whilst accumulating a pool of molten slag which can be removed either continuously or intermittently by tapping.
  • the molten carrier materials in the refining loops are involved chemically in the process because the metal being produced is dissolved therein and impurities such as carbon, silicon, sulphur and phosphorus interact thermodynamically with each other in ways that can influence the choice and effectiveness of refining processes to which the molten carrier materials are subjected, it being appreciated that because of the large melt circulation ratios established in the refining loops and already referred to for the reduction loop, the molten product overflowing from these loops is virtually the same as the molten carrier and the melt composition throughout a particular loop is effectively constant and temperature differences in the bulk of the molten carrier throughout are relatively minor.
  • An optional final step in the process for producing molten refined metal or alloy is to cause the molten metal, either overflowing or being siphoned out from the last of the melt circulation refining loops, to irrigate solid packing elements within a packed tower with molten metal flowing by gravity downwards in the form of droplets and rivulets with a rising gas flow such that true countercurrent contact is maintained between the gas and liquid phases with longitudinal or backmixing reduced to an absolute minimum.
  • a preferred way of achieving this true counterflow is to operate the tower under reduced pressure so that the downward velocity of the liquid metal droplets and rivulets is less than the upwards velocity of the gas.
  • any suitable relatively large packing elements may be used with 100-150 mm MgO or MgO/Al 2 O 3 spinel being a preferred choice.
  • the diameter of the ULC Tower it is important to keep below the so-called flooding condition and also the gas phase pressure drop should only be a minor fraction of the total pressure.
  • an elaborate vacuum system is not required and all that is needed is a water ring pump to exhaust the purge gas and its associated carbon monoxide at a pressure in the region of lOOmbar.
  • the method of this aspect of the present invention is suitable for direct coal-based continuous steelmaking from fine coal and iron ore fines.
  • the molten carrier material in the reduction loop is not formed directly from the charge material, it is convenient to use hot metal (hot molten iron, impure in the as- smelted state) as the molten carrier material and to add or remove hot metal from the first loop as the on-going process demands.
  • the iron produced by reduction forms the carrier material, which is removed, preferably continuously, at a rate which substantially balances the rate of iron production.
  • Oxygen should be used for post combustion of carbon monoxide generated during reduction, but first the carbon monoxide should be partially combusted with oxygen in a step-wise fashion to provide the gaseous oxidant for top blowing along with water vapour derived from hydrogen in the reductant for steelmaking rather than using oxygen directly.
  • Sequential combustion of the carbon monoxide also permits heat to be generated for melting the metallised raft in the first of the steelmaking loops, whilst maintaining iron as the thermodynamically stable phase so iron oxide is not formed at unit activity and the problem of refractory attack is greatly reduced.
  • processes of the future except for uncontaminated nitrogen from air separation, processes of the future must move ideally towards zero gas emission after sequestration of the carbon dioxide.
  • oxygen processing is needed but not in the way it is used in current steelmaking practice.
  • the gas phase will be principally hydrogen diluted with nitrogen or just hydrogen.
  • the gaseous mixture required for primary and secondary steel making will be N 2 /H 2 O again ensuring that no free oxygen comes into direct contact with carbon containing molten iron anywhere in the process.
  • this is secured by adapting the processing conditions so that the supply of carbon to the melt surface by liquid phase mass transfer throughout all of the steelmaking loops is always adequate to prevent oxygen atoms from diffusing into the molten metal to such an extent that concentrations of both oxygen and carbon in the bulk molten iron reach supersaturation levels sufficient to induce the decarburisation reaction to occur spontaneously beneath the surface.
  • Fig. 1 is a schematic general arrangement in plan view of the plant for direct coal-based continuous steelmaking, when steel scrap, hot briquetted iron (HBI), or direct reduced iron (DRI) are readily available and their use is economical.
  • HBI hot briquetted iron
  • DI direct reduced iron
  • Fig. 2 is a schematic general arrangement in plan view for direct coal-based continuous steelmaking for a stand-alone plant based on virgin ore as the only source of iron units.
  • the plant comprises six furnace hearths 1, 2, 3, 4, 5 and 6, which are arranged in pairs to form three inter-linked melt circulation loops A (a charge reduction loop), B and C (first and second refining loops) formed by interconnecting the first and second hearths 1 and 2 (constituting a charge reduction and a desulphurisation/heating zone respectively), the third and fourth hearths 3 and 4 (constituting a melting zone and a desulphurisation/decarburisation zone) and the fifth and sixth hearths 5 and 6 respectively.
  • A a charge reduction loop
  • B and C first and second refining loops
  • the third and fourth hearths 3 and 4 constituting a melting zone and a desulphurisation/decarburisation zone
  • fifth and sixth hearths 5 and 6 respectively.
  • molten metal is caused to overflow or be otherwise taken out of the second and third loops B and C by conductively heated siphons 7 and 8 so that molten metal issuing from these is equivalent to the metal in the composite charge initially added to the top surface of the molten carrier material at the upstream end of the first hearth 1, together with any scrap or pre-reduced material added to the circuit and shown in Fig. 1 as 12.
  • a channel or ramp 8 is provided to permit solid material (metallised raft) floating on the surface of the molten carrier material in the first hearth 1 to be propelled or projected into the third hearth 3 onto the surface of the molten carrier material in the first refining loop B, along with a lesser amount of molten carrier material from the reduction loop A, corresponding to new metal assimilated into the carrier material in reduction loop A, resulting from any smelting reduction taking place between the floating charge layer, ultimately becoming an agglomerated solid structure referred to as the metallised raft as it progresses downstream in the first hearth 1.
  • R-H type snorkels 9 connected to vertical bodies 10 linked to each other by horizontal members 11 to form vacuum-tight refractory-lined vessels, which can function either as gas-lift pumps or siphons depending on whether or not an inert gas is injected into the upleg snorkels.
  • melt is drawn up into both snorkels 9 and the lower regions of the vertical bodies 10 and the horizontal members 11 in each unit to form a channel through which the melt traverses as it flows from one hearth to another along the horizontal member 11.
  • These vessels can be either lowered so that the snorkels 9 are immersed in the molten carrier materials or raised for stand-by or replacement with preheated units on a scheduled maintenance basis.
  • the very much smaller siphons 7 and 8 have similar features to the units described above, but because the melt flow rates in these siphons correspond to the actual metal production rate, steps may need to be taken to independently heat the flowing metal by direct resistance heating or so-called conductive heating.
  • the composite charge 12, comprised of well-mixed iron ore fines, fine coal and preferably burnt lime flux, is distributed uniformly onto the surface of the molten carrier material towards the upstream end of the first hearth 1 to form a floating charge layer 5 to 10 cm in thickness, whilst being heated from beneath by the molten carrier material.
  • Coal volatiles and reaction product gases are discharged from the gas space above the floating solid charge into a refractory-lined gas header duct 13, which forms the manifold for an array of top blowing lances with concentric controlled oxygen admission so that the metallised raft floating in the third hearth 3 is melted to form a liquid slag layer, whilst the metallics are assimilated into the molten carrier material.
  • Slag is removed at the downstream end of the third hearth 14 either continuously or intermittently from a pool of molten slag formed when the molten metal is held back by an electromagnetic device or dam similar to that being developed for continuous casting applications.
  • the gases flow from the third hearth 3 into a hot gas clean-up (HGCU) facility, which incorporates a combined liquid-metal quench and desulphurisation tower 15, a turbo-booster 16 and a liquid-metal based gas reheater 17.
  • HGCU hot gas clean-up
  • the gases are arranged to flow into the HGCU facility from the first hearth.
  • the hot gas from the HCGU flows into a refractory-lined header duct 18, which forms the manifold for an array of top blowing lances with further controlled concentric oxygen addition so that carbon dioxide and water vapour become the oxidant gases rather than oxygen itself for primary or major decarburisation of the molten carrier metal in the fourth hearth 4 using direct flame impingement to provide both the thermal requirements and the gaseous reactant for the endothermic decarburisation reaction.
  • the fourth hearth 4 is used to effect flux-based desulphurisation, whilst the dissolved oxygen content of the iron is relatively low and the carbon level sufficiently high to sustain this requirement. Accordingly, desulphurisation flux is added at the upstream end of the fourth hearth 19 and removed at its downstream end 20.
  • the hot gases from the fourth hearth 4 discharge into a refractory-lined header duct, which forms the manifold for an array of top blowing lances 21 with further concentric controlled oxygen addition to effect melting of preheated steel scrap or prereduced material in a pool of molten metal 22, which overflows liquid scrap into the fifth hearth 5 where the melt is flowing at an accelerated rate in the end in which open-channel decarburisation of the melt siphoned from the fourth hearth 4 is effected by contacting the melt in the fifth hearth 5 with the oxidising gases leaving the pool melter 22 under turbulent flow conditions.
  • the sensible heat of the gases leaving the pool melter 22 is more than adequate to provide the endothermic requirements of secondary decarburisation before the gas flows into the sixth hearth 6 via the refractory-lined cross-over gas duct 23. Because the carbon level throughout the second refining loop C is low, the melt is effectively steel for general purpose applications and the dissolved oxygen level is high enough to conduct flux-based dephosphorisation by adding powdered flux at the upstream end 24 of the sixth hearth and removing flux at the downstream end 25.
  • the hot gases discharge into a refractory-lined transfer duct 26, which becomes the manifold 27 for an array of top blowing lances with major concentric oxygen addition (or other suitable configuration such as mutually opposed jets) to effect combustion to completion of the gases emitted initially from the reduction loop A via the off-take 13 into the first of the refining (steelmaking) loops B.
  • This major combustion ultilises direct flame impingement onto the molten carrier material in the second hearth 2 to contribute towards the post combustion energy needed to sustain ironmakmg in the first hearth 1.
  • a small amount of a desulphurisation flux which wets the melt surface and spreads across it to form a continuous thin film on the surface of the molten carrier material, is added at the upstream end 28 of the second hearth 2 and taken away at its downstream end 29. This contributes to desulphurisation in the circuit, but most importantly raises the emissivity of the molten carrier material and so considerably enhances heat transfer by radiation.
  • the very hot combustion gases are discharged into a refractory-lined off-take 30, possibly with stave cooling within the refractory lining, directly into a countercurrent radiant scrap preheater 31, in which a sloping hearth plus a mechanical device is used to contact selected steel scrap 39 to effect major scrap preheating and possible partial melting, before the scrap or other reduced material passes into the pool melter 22.
  • the off-gas from the scrap preheater leaves the plant at 32 and can be used in a heat recovery steam generator (HRSG) for advanced power generation.
  • HRSG heat recovery steam generator
  • Vacuum degassing of steel using the RH process is established practice throughout the world. By injecting argon into a single upleg, molten steel circulation at rates up to about 200 tonne per minute can be obtained and this is now regarded as state of the art in the steel industry.
  • elaborate vacuum plant as used in RH degassing is not needed for the melt circulation systems in the present invention.
  • Argon can be used as the lift gas but it may be preferable to use the desulphurised gas arising from ironmaking whilst it is still not oxidising iron, because argon is needed elsewhere in the circuit, particularly if ultra-low carbon steel (ULC) is to be produced continuously using the molten steel discharging from 8 as the feed into the Tower Refiner described previously.
  • ULC ultra-low carbon steel
  • the gases emitted from the ironmaking loop A need to be utilized together in both of the steelmaking loops B and C.
  • the smelting reduction gases in total need to be passed directly to the metallised raft melting arm (hearth 3) of the primary steelmaking loop A and partially combusted with oxygen with direct flame impingement using an array of top blow lances to effect iron melting and liquid slag formation as the metallised raft floats along with the circulating iron carbon melt with phase disengagement completed when a molten slag layer free from of associated iron is established towards the downstream end of the arm in question, in advance of slag removal from the circuit.
  • metallic iron is maintained as the thermodynamically stable phase by controlling the oxygen addition in both the smelting reduction arm (hearth l)of the ironmaking loop A and the metallised raft melting arm (hearth 3) of the primary steelmaking loop B.
  • Direct flame impingement was selected so that metallic iron at unit activity can be melted directly without relying on dissolution in the Fe-C melt. Similarly, the processes involved in slag formation are accelerated by this approach.
  • the hot gases undergo hot gas cleanup (HGCU) involving a liquid metal quench, which incorporates sulphur removal to a very high level as well as removal of particulate solids, before being boosted in pressure to around 0.5 to 1 bar gauge and reheating again by liquid metal direct heat exchange.
  • the gases are returned to the steelmaking loop B at about 1350°C for partial combustion with oxygen to provide the chemical and thermal requirements for major decarburisation of Fe-C melt by direct flame impingement under non-splashing top blow conditions on the desulphurisation flux arm (hearth 3) of the primary steelmaking loop B.
  • the momentum of the jets clears the flux away and mixes it to assist desulphurisation, whilst promoting liquid phase mass transfer of dissolved carbon from the bulk of the liquid metal to the interface, where the endothermic reactions with CO and H 2 O take place.
  • the top blow lances are designed so that the supply of gaseous oxidant to the liquid metal interface at steady state is balanced by the supply of carbon by liquid phase mass transfer. Allowance is also made for the kinetics of the dissociative adsorption of both CO 2 and H 2 O, including the inhibiting effects of sulphur. The resulting steady state conditions are such that sub-surface CO bubble formation cannot take place. Laboratory experiments using the electromagnetic levitation technique have established that sparking or copious fume generation will not occur under these relatively mild conditions.
  • the gases during decarburisation may gain enough CO by reaction that they may leave the primary steelmaking loop A with metallic iron again as the stable thermodynamic phase. Further controlled addition of oxygen is made to these gases in another top-blow flame impingement arrangement, this time directed at a pool of molten iron , which is essentially a cul-de-sac off the second refining loop C for what is termed open-channel decarburisation.
  • This pool receives partially melted steel scrap from a radiant heater in the form of a sloping hearth, leading directly into the pool and fired by the very hot gases from the second hearth.
  • the overflow from the pool is liquid scrap, which joins the main melt circulation flow, any non-metallic residues being incorporated into the dephosphorisation flux layer as it floats down this arm (hearth 5) of the open-channel decarburisation loop C.
  • the hot gas mixture then transverses the length of the open-channel decarburisation arm (hearth 5), where a clean metal surface permits further decarburisation to a low level without sparking or fume emission and then the hot gases are ducted to the heating arm 2 of the ironmaking loop A where further oxygen is added for full combustion before exiting to the sloping hearth radiant heater for partial melting of steel scrap at a temperature at between 1700-1800°C at the inlet with countercurrent contacting of the incoming scrap feed.
  • HRSG heat recovery steam generator
  • a stand-alone plant retains the principal features of having six furnace hearths, which are arranged in pairs to form three inter-linked melt circulation loops. Except for the changes discussed above in relation to the non-availability of steel scrap at the right price and assuming that using HBI or DRI is also not economic, the other features in Fig. 2 are essentially the same as those shown in Fig. 1 and corresponding reference numerals are used accordingly. For the stand-alone plant, however, since excess thermal energy is available, it may be desirable to incorporate calcination of limestone 33 to burnt lime 34 into the circuit. This is shown schematically in Fig.
  • the method according to the present invention is not solely applicable to iron oxide ores such as haematite, but is also applicable for example, to the production of refined metal or alloy from the following:

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacture Of Iron (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

L'invention concerne un procédé de réduction de matériau d'oxyde métallique en métal consistant à réaliser une circulation forcée de matériau support fondu dans une boucle fermée comprenant à la suite une zone de réduction de charge sur un bras de la boucle, une combinaison de zone de désulfuration à l'état fondu et d'une zone de postcombustion ou de chauffage sur l'autre bras, à réduire l'oxyde métallique en métal solide grâce au matériau carboné contenu dans une charge composite mélangée d'oxyde métallique, de réducteur carboné et de fondant dans la zone de réduction, l'oxyde métallique et le réducteur carboné étant utilisés en proportions telles que le carbone du réducteur carboné est transformé en monoxyde de carbone, à faire réagir le monoxyde de carbone avec de l'oxygène en aval de la boucle d'affinage avant sa combustion complète dans la zone de chauffage à la surface du matériau support fondu de façon que la chaleur produite par la réaction soit transférée au matériau support fondu circulant vers la zone de réduction, à séparer un flottant métallisé du matériau support fondu par projection de ce fondant dans la première boucle d'affinage en vertu de la force de traînée exercée sur le fondant par le matériau support fondu avant que ce matériau ne circule vers la zone de chauffage de façon que la surface du matériau support fondu, dirigée vers la zone de chauffage, ne contienne sensiblement plus de matériau solide.
PCT/GB2003/003065 2002-07-15 2003-07-15 Production directe de metaux et d'alliages affines Ceased WO2004007775A2 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP03764006A EP1521851A2 (fr) 2002-07-15 2003-07-15 Production directe de metaux et d'alliages affines
AU2003254456A AU2003254456A1 (en) 2002-07-15 2003-07-15 Direct melting and refining of metal oxide material
US10/521,306 US20060162498A1 (en) 2002-07-15 2003-07-15 Direct production of refined metals and alloys

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0216484.6 2002-07-15
GBGB0216484.6A GB0216484D0 (en) 2002-07-15 2002-07-15 Direct production of refined metals and alloys

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WO2004007775A2 true WO2004007775A2 (fr) 2004-01-22
WO2004007775A3 WO2004007775A3 (fr) 2004-04-29

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GB (1) GB0216484D0 (fr)
WO (1) WO2004007775A2 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005118890A3 (fr) * 2004-05-29 2006-04-27 Noel Warner Recuperation d'acier dans de la ferraille a trier
WO2008017797A1 (fr) * 2006-08-11 2008-02-14 Noel Warner Post-combustion avec radiation
JPWO2006038443A1 (ja) * 2004-10-04 2008-05-15 チッソ石油化学株式会社 液晶組成物および液晶表示素子
CN112850645A (zh) * 2021-02-08 2021-05-28 赛鼎工程有限公司 焦炉煤气深度净化制合成氨的系统及方法

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US10099868B1 (en) * 2017-04-20 2018-10-16 Otto Kierulff Da Costa Set of water pipes with capsules for heavy cargo and irrigation transportation system
CN113528821B (zh) * 2019-07-29 2023-05-02 孙旭阳 利用单原子碳还原制备单质材料的方法
CN114574651B (zh) * 2022-01-24 2023-05-05 山东大学 一种旋流铁壁熔融冶炼装置及方法

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GB1046675A (en) * 1964-10-16 1966-10-26 Air Liquide Improvements in or relating to the production of steel
US4741770A (en) * 1985-04-03 1988-05-03 Cra Services Limited Zinc smelting process using oxidation zone and reduction zone
US4701217A (en) * 1986-11-06 1987-10-20 University Of Birmingham Smelting reduction
US5060913A (en) * 1989-08-30 1991-10-29 Regents Of The University Of Minnesota Integrated metallurgical reactor
GB9211052D0 (en) * 1992-05-23 1992-07-08 Univ Birmingham Synthetic rutile production
GB9305560D0 (en) * 1993-03-18 1993-05-05 Univ Birmingham Method of recovering zine
LU90273B1 (de) * 1998-08-11 2000-02-14 Wurth Paul Sa Verfahren zur thermischen Behandlung schwermetall-und eisenoxidhaltiger Reststoffe

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005118890A3 (fr) * 2004-05-29 2006-04-27 Noel Warner Recuperation d'acier dans de la ferraille a trier
GB2437374A (en) * 2004-05-29 2007-10-24 Noel Alfred Warner Recovery of steel from contaminated scrap
GB2437374B (en) * 2004-05-29 2010-03-24 Noel Alfred Warner Recovery of steel from contaminated scrap
JPWO2006038443A1 (ja) * 2004-10-04 2008-05-15 チッソ石油化学株式会社 液晶組成物および液晶表示素子
JP4957247B2 (ja) * 2004-10-04 2012-06-20 Ｊｎｃ石油化学株式会社 液晶組成物および液晶表示素子
WO2008017797A1 (fr) * 2006-08-11 2008-02-14 Noel Warner Post-combustion avec radiation
CN112850645A (zh) * 2021-02-08 2021-05-28 赛鼎工程有限公司 焦炉煤气深度净化制合成氨的系统及方法
CN112850645B (zh) * 2021-02-08 2022-09-06 赛鼎工程有限公司 焦炉煤气深度净化制合成氨的系统及方法

Also Published As

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GB0216484D0 (en) 2002-08-21
WO2004007775A3 (fr) 2004-04-29
AU2003254456A8 (en) 2004-02-02
EP1521851A2 (fr) 2005-04-13
AU2003254456A1 (en) 2004-02-02
US20060162498A1 (en) 2006-07-27

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