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
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/02—Working-up flue dust
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B13/00—Making spongy iron or liquid steel, by direct processes
  • C21B13/14—Multi-stage processes processes carried out in different vessels or furnaces
• • 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
  • 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
• • 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 invention relates to a method and a plant for the recycling of iron and heavy metal-containing residues and possibly iron ore.
• a major problem of the iron and steel producing industry lies in the constantly accumulating amounts of iron and heavy metal-containing residues, such as furnace dust, sludge, mill scale and the like, which are only accessible for recycling with great effort and are therefore usually landfilled without being dumped to take advantage of their valuable content.
• a method of the type described at the outset is the INMETCO method.
• iron-rich metallurgical residues are agglomerated with solid reducing agents to form unburned, so-called "green" pellets and reduced in a rotary hearth furnace, the heavy metals evaporating, extracted with the exhaust gas and then melted in a melting furnace or optionally hot briquetted.
• a problem with the production of pig iron is the presence of fine ore in relatively large quantities, which is difficult to handle in the reduction and melting process. So The fine ore is usually reduced in fluidized bed reactors, which involve a great technical outlay. The introduction of the reduced fine ore into a smelting furnace also requires apparatuses with complex equipment, the service life of which is extremely limited due to the wear caused by the reactivity of the sponge iron.
• EP-A-0735146 A device for reducing and smelting iron ore is described in EP-A-0735146.
• iron ore is reduced and melted in a melting cyclone and enters a metallurgical vessel immediately below the melting cyclone, in which the final reduction takes place with the formation of a process gas from coal and oxygen blown onto the slag / metal layer and the complete melting of the iron takes place.
• the reducing process gas is partially burned with oxygen and in this way provides the heat necessary for the melt and the reduction both in the melting vessel and in the melting cyclone.
• the exhaust gases are drawn off at the top opening of the melting cyclone.
• the melt To separate slag and pig iron, the melt must first be transferred to a settling vessel, since in these known devices only one tap opening is provided in the lower vessel.
• the invention aims at eliminating these disadvantages and has as its object to create a method and a system which make it possible to use iron and heavy metal-containing residues, in particular from the iron and steel producing industry, and optionally iron ore in an environmentally friendly manner - while avoiding landfilling - To be processed, whereby the iron can be recycled, ie steel production benefits. Furthermore, only a single exhaust gas stream is generated, which saves system costs and minimizes emissions and increases the possible efficiency of energy recovery.
• this object is achieved by the combination of the following features: the residues and, if appropriate, the iron ore are introduced into a melting cyclone with backflow, reducing agents and oxygen are additionally introduced and swirled into the melting cyclone,
• Iron is reduced to at least FeO in the melting cyclone
• Heavy metals are reduced to metals in the melting cyclone and converted into the gas phase by evaporation, the resulting gas, which may contain heavy metals, the partially reduced iron and the slag are transferred to a directly coupled furnace, energy is supplied to the furnace, and reducing agents are added to the furnace and brought in oxygen or oxygen-enriched air,
• iron iron-containing
• hetero metal metal-containing
• heterometal-containing each encompass both the respective metals in oxidized, for example oxidic, form and in reduced, ie metallic, form, both oxidized and reduced, as just one of the two, the exact meaning of which is clear from the context.
• Reduction to FeO always means a reduction from trivalent to divalent iron, for example from Fe 2 O to 2 FeO, but also from 3 Fe O 3 to 2 Fe 3 O 4 (ie to Fe 2 O 3 »FeO).
• Fine ore can also advantageously be used as an iron-containing residue, in particular with a proportion of very fine particles that originate from ore processing or from abrasion from a pelletizing device.
• reducing agents which are advantageously introduced in solid, liquid or gaseous form, and oxygen, preferably technical oxygen or oxygen-enriched air, takes place horizontally, preferably tangentially, in the vertically arranged melting cyclone, as a result of which the processes of mass and heat transfer take place very quickly.
• Reducing agents and oxygen are added in such controlled amounts that the heavy metals are converted into the gas phase by evaporation in a metallic state during the melting process and the iron is reduced at least to the divalent iron oxide FeO.
• the heavy metal-containing gas, the partially reduced iron and the slag are transferred from the melting cyclone into the furnace by means of a connecting line which is arranged between the bottom opening of the melting cyclone and a furnace immediately following the melting cyclone, preferably through the ceiling or through a side wall of the furnace, and optionally via a maximum of one intermediate chamber arranged on the wall of the furnace, which separates the melting zone from the Reduction zone allowed in the furnace.
• the intermediate chamber, into which the connecting line opens, can also be designed as a furnace exhaust line.
• solid reducing agent preferably coal or carbon-containing wastes (which are at least partly formed by fine particles)
• oxygen or oxygen-enriched air is blown into the melt with oxygen or oxygen-enriched air.
• These substances can be blown in using under-bath blowers or using lances that are immersed in the slag layer floating on the molten iron metal.
• the oven is provided with openings for the lances.
• the injection nozzles are expediently located in part below the metal bath level and are connected to supplies for reducing agents and / or oxygen.
• the lances can be arranged in the furnace in any manner known to those skilled in the art.
• the reduced metal droplets settle at the bottom of the furnace in the molten iron metal, which, like the slag, can advantageously be separated continuously or discontinuously from the furnace using its own tap hole.
• a portion of coarse fraction can be charged directly into the furnace, preferably via a suitable feed opening into the furnace, for example in the ceiling or in a side wall of the Oven.
• energy is supplied to the furnace, which also prevents premature separation of the heavy metals in the region of the furnace.
• the energy is preferably supplied to the melt in the form of electrical energy, for example via a direct arc.
• the supply of the electrical energy by means of at least one electrode protruding into the furnace has proven to be particularly advantageous, both direct current and alternating current being possible.
• the evaporated heavy metals are subjected to post-combustion together with the furnace exhaust gas directly at the gas outlet, as a result of which the heavy metals are converted into a solid oxidic form which, after separation from the remaining exhaust gas, can be further processed in a precipitation device. If the products originating from the melting cyclone, namely heavy metal-containing gas and melt, are first introduced into an intermediate chamber, the heavy metal-containing gas is introduced into the furnace exhaust gas, which is withdrawn from the furnace via the intermediate chamber, in this intermediate chamber, whereupon the further treatment of the gases done together.
• the melting cyclone, the furnace vessel above the metal mirror and, if applicable, the intermediate chamber are expediently equipped with evaporative cooling, as a result of which the radiant heat from the furnace and the melting cyclone are used to evaporate cooling water and can thus be obtained in the form of steam, which can be used in an iron and steel mill to save energy .
• Exhaust gas cooling carried out after the afterburning of the heavy metal-containing gas and the furnace exhaust gas serves the same purpose, preferably in a steam boiler.
• the heat inherent in the exhaust gas can also be used in whole or in part in a heat exchanger into which the exhaust pipe of the furnace opens, the heated air being able to be fed to a dryer which contains suitable iron and heavy metal-containing moist residues or, respectively, for use in the melting cyclone Sludge dries.
• FIGS. 1 to 4 showing preferred embodiments of the system according to the invention in a schematic representation.
• coal, oxygen and iron- and heavy metal-containing residues and possibly iron ore in the form of dust are introduced into a vertically arranged melting cyclone 1.
• the introduction takes place in such a way that the swirling and the associated mass and heat transfers take place very quickly according to the invention, as a result of which the melting and pre-reduction process as a whole has a high space-time yield.
• the controlled delivery of the substances to be introduced into the melting cyclone 1 is carried out by a metering device (not shown) known to the person skilled in the art.
• the substances are blown horizontally, preferably tangentially, into the melting cyclone 1 via a plurality of openings, which can be distributed over the entire melting cyclone jacket.
• the melting cyclone 1 In the interior 2 of the melting cyclone 1 there is a reduction of the iron and heavy metal-containing residues and possibly of the iron ore, with iron being reduced at least to FeO and the heavy metals to the metal. Furthermore, a melting of the reduced iron-containing material and a transfer of the heavy metals into the gas phase is effected quickly and efficiently due to a cyclone-specific backflow.
• An opening 3 in the bottom 4 of the melting cyclone 1 is formed by a constriction, which causes the backflow in the interior 2 of the melting cyclone 1 and thus enables a minimal degree of dusting.
• the melting cyclone 1 is in direct connection with a furnace 5 arranged below the melting cyclone 1.
• the melt products and the heavy metal-containing gas enter the furnace 5 from above via a connecting line 6.
• the furnace 5 there are a metal bath 7 (iron bath) and a slag layer 8 floating on the metal bath 7, which are separated from the furnace 5 via tap openings 9 and 10. Furthermore, the furnace 5 according to this embodiment has three electrodes 11, 11 ', 11 ", which dip into the slag layer 8 from above and which supply the energy required for maintaining a liquid slag 8 and a metal bath 7 in the form of arcs For example, the electrodes 11, 11 ', 11 "are operated with alternating current, but operation with direct current would also be possible, the furnace 5 having only one electrode 11.
• Reducing agent and / or oxygen is introduced into the furnace 5 via under-bath injection nozzles 12 in a side wall 13 of the furnace 5 or in the base 14.
• the injection nozzles 12 are preferably arranged in part below the metal bath level.
• a lance 15 for blowing in coal and oxygen is provided in the embodiment according to FIG. 1, which projects obliquely into the furnace 5 through the side wall 13 of the furnace 5 and dips into the slag layer 8 with its lower end.
• a feed 16 opens into the furnace 5 for a coarse fraction of a reducing agent or a residue that can be introduced.
• the iron-containing melt introduced into the furnace 5 from the melting cyclone 1 is completely reduced in the slag layer 8 with the aid of the reducing agent and oxygen, and the liquid iron is separated into the metal bath 7.
• air is supplied to the exhaust gas and afterburning 21 is initiated.
• a part of the increased energy content of the exhaust gas is transferred to water in a waste heat boiler 17, the heat content of the exhaust gas being used to generate steam.
• a turbine generator 18 is used as an example for the further use of the steam, which is used to generate electricity.
• other possible uses of the steam generated are also conceivable, for example use in a metallurgical plant for cooling purposes, etc.
• the cooled exhaust gas is fed to a filter 19, in which the condensed heavy metals which accumulate as dust are separated from the remaining exhaust gas.
• the preferred embodiment shown in FIG. 2 differs from the one illustrated in FIG. 1 by the manner in which the heavy metal-containing gas and the melting material from the melting cyclone 1 are introduced into the furnace 5.
• the connecting line 6 opens into the side wall 13 of the furnace 5.
• the reducing agent and the oxygen are introduced into the furnace 5 exclusively via under-bath injection nozzles 12.
• the further treatment of the exhaust gas after it has left the furnace 5 is not shown further; it can also be carried out as shown in FIG. 1.
• the connecting line 6 opens into an intermediate chamber 20, which is optionally widened (shown in dashed lines), so that the heavy metal-containing gas from the melting cyclone 1 does not have to flow through the furnace 5 and the melting material is already on the way through the reducing furnace exhaust gas the furnace 5 is further reduced.
• the lance 15 used to blow in the reducing agent and oxygen projects into the furnace 5 from above. However, it can also protrude over a side wall 13 in the furnace 5.
• FIG. 4 shows the arrangement of melting cyclone 1 and furnace 5 described in FIG. 1, but the heat inherent in the exhaust gas is only partially used in the waste heat boiler 17.
• the still hot exhaust gas is heat exchanged in a recuperator 22 and then passed in a cooled state into the filter 19, where the described separation of the heavy metals takes place.
• the air heated in the recuperator 22 is fed to a dryer 23 which serves to dry moist residues and sludges for use in the melting cyclone 1.
• the process sequence according to the invention is set out in the examples 1, 2 and 3 below.
• the quantities given below relate to a ton of feed mix without coal or surcharges (lime).
• the partially reduced iron was then completely reduced in the reduction furnace with 182 kg / t coal and 36 NmVt oxygen and melted.
• the conveying air volume for the solids blown through lances or nozzles was 45 NmVt.
• the electricity requirement of the furnace was 320 kWh / t.
• the amount of reducing agent (coal) introduced into the furnace was 151 kg / t, 30 NmVt in oxygen and 38 NmVt in conveying air.
• the electricity requirement was 268 kWh / t.
• the products produced were 625 kg / t molten metal, 139 kg / t slag, 15760 NmVt dedusted exhaust gas and 22 kg / t dust. 945 kWh / t of electricity were generated.

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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)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Manufacture And Refinement Of Metals (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

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Citations (4)

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• 1999
  • 1999-05-14 AT AT0086599A patent/AT407878B/de not_active IP Right Cessation
• 2000
  • 2000-03-28 BR BR0010527A patent/BR0010527A/pt not_active Application Discontinuation
  • 2000-03-28 CA CA 2372809 patent/CA2372809A1/en not_active Abandoned
  • 2000-03-28 EP EP00920595A patent/EP1194596A1/de not_active Withdrawn
  • 2000-03-28 WO PCT/EP2000/002702 patent/WO2000070101A1/de not_active Application Discontinuation

Patent Citations (4)

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