EP1115890A1 - Method for producing directly reduced metal in a multi-tiered furnace - Google Patents

Method for producing directly reduced metal in a multi-tiered furnace

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Publication number
EP1115890A1
EP1115890A1 EP99947270A EP99947270A EP1115890A1 EP 1115890 A1 EP1115890 A1 EP 1115890A1 EP 99947270 A EP99947270 A EP 99947270A EP 99947270 A EP99947270 A EP 99947270A EP 1115890 A1 EP1115890 A1 EP 1115890A1
Authority
EP
European Patent Office
Prior art keywords
deck oven
metal oxides
deck
furnace
oven
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99947270A
Other languages
German (de)
French (fr)
Inventor
Jean-Luc Roth
Thomas Hansmann
Romain Frieden
Marc Solvi
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.)
Paul Wurth SA
Original Assignee
Paul Wurth SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Paul Wurth SA filed Critical Paul Wurth SA
Publication of EP1115890A1 publication Critical patent/EP1115890A1/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in 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
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • C21B13/105—Rotary hearth-type furnaces
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/16—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a circular or arcuate path
    • F27B9/18—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a circular or arcuate path under the action of scrapers or pushers
    • F27B9/185—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a circular or arcuate path under the action of scrapers or pushers multiple hearth type furnaces
    • 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

Definitions

  • the present invention relates to a method for producing directly reduced metal in a deck oven.
  • Multi-deck furnaces are used to manufacture metals from the corresponding
  • Metal oxides are used, a metal oxide and a reducing agent being introduced into the deck oven and reacting with one another at high temperature.
  • the metal oxides and the reducing agent are introduced into the deck furnace and raked by rakes that protrude over the individual floors and conveyed to the edge of the floor, from where they fall through a number of openings provided on a lower level. From there, the metal oxides mixed with reducing agents are transported to the middle of the floor and then fall to the floor below. During the transport from top to bottom through the deck oven, the metal oxides and the reducing agents are gradually heated.
  • the deck oven is heated with gas burners or the like and part of the reducing agent - generally the volatile part of a carbon carrier such as coal - is burned in the deck oven by blowing in an oxygen-containing gas.
  • the process heat required is generated by burning the coal and the gas burners, and carbon dioxide is produced.
  • the carbon dioxide contained in the hot gases reacts with the carbon in the deck oven to form carbon monoxide according to the Boudoir equilibrium.
  • the carbon monoxide thus formed reduces the metal oxides to metal.
  • the carbon monoxide content of the gases in the stage furnace essentially determines the reduction potential.
  • a disadvantage of this method is that oxidized gases and oxygen are introduced into the deck oven where reduction is to take place. Furthermore, a large amount of exhaust gases falls to be treated.
  • This object is achieved according to the invention by a method for producing directly reduced metal! in a deck oven, characterized in that metal oxides and reducing agents are introduced into the deck oven and the process heat required to reduce the metal oxides is generated by indirectly heating individual floors of the egg oven.
  • the process heat is supplied to the deck oven by radiation energy and not by combustion of the reducing agent in situ or by gas burners as in the known methods.
  • a major advantage of the invention is that no oxygen or other oxidized gases have to be blown into the deck oven in order to generate the required process heat. This significantly reduces the amount of gases circulating in the deck oven. Only much smaller amounts of exhaust gas need to be post-treated, which makes the process cheaper.
  • the gas velocities on the individual floors are lower due to the lower gas quantities. Less dust is whirled up and removed from the deck oven. Since no oxygen or other oxidized gases are blown into the deck oven, the reduction potential of the gases within the deck oven is higher than with known deck ovens.
  • the individual floors are indirectly heated independently of one another.
  • this method allows the deck oven and its contents to be heated more evenly.
  • the process can be carried out under a pressure of 1 to 5 bar, which means that the deck oven can be made more compact. Electrical heating resistors are advantageously used for indirect heating of individual floors.
  • gaseous reducing agents are advantageously used! used.
  • the metal oxides are e.g. around iron ore, zinc ores, oil and iron oxide-containing wastes, and various problem wastes, e.g. iron oxide-containing dusts contaminated with zinc oxides and / or other heavy metal oxides.
  • the invention also relates to a deck oven, which comprises several superposed floors, for producing directly reduced metal.
  • the multi-level furnace according to the invention is characterized by means for indirect heating of individual levels which generate the process heat required to reduce the metal oxides
  • the deck oven can, for example, be brought to the required temperature and kept at this temperature by means of electrical heating resistors which are fitted inside the deck oven. It is therefore possible to specifically set the temperature on each floor without significantly influencing the conditions on the next floors. In contrast to the traditional deck oven, the conditions on the different floors can be influenced independently of each other. With the same capacity and gas velocities on the levels, the level furnace for producing directly reduced metal can be smaller than a conventional level furnace using the method according to the invention.
  • the indirect heating elements can be attached to the surface and / or below the individual floors. But they can also be attached to the side wall.
  • This process is particularly advantageous in the direct reduction of iron ore.
  • Fig.2 the schematic arrangement of the electrical heating resistors in the deck oven.
  • Fig. 1 shows a section through a deck oven 10, the several - in this
  • the cover 16 of the deck oven 10 there is a fume hood 20 through which the gases can be evacuated from the deck oven 10 and an opening 22 through which metal oxides and the reducing agent can be applied to the top floor.
  • the metal oxides can also be introduced further below in the deck furnace 10 separately from the reducing agents
  • a shaft 24 is attached, to which rakes 26 are attached, which protrude above the respective floors 12.
  • the shaft 24 and the rake 26 are air or water cooled.
  • the rakes 26 are designed in such a way that they roll the material from the outside inwards on one floor and then from the inside out on the floor below, in order to transport the material through the deck oven 10 from top to bottom.
  • the metal oxides are either mixed with solid reducing agents such as lignite coke, petroleum coke, or coal outside the deck furnace 10, and the mixture of metal oxides and reducing agent is then applied to the top floor.
  • the metal oxides can also be applied separately to the top floor and the solid reducing agents are introduced further down through an inlet opening 30 in the jacket 14 into the deck oven 10.
  • the metal oxides can possibly be pre-dried outside the deck oven 10 before or after they are mixed with the solid reducing agents.
  • the mixture of metal oxides and reducing agents After the mixture of metal oxides and reducing agents has been applied to the first floor of the deck furnace 10, it is circulated by the rakes 26 and conveyed to the edge of the deck, from where it falls through a plurality of openings 28 provided therefor onto the floor below. From there, the metal oxides mixed with reducing agents are transported to the middle of the floor and then fall to the floor below. The metal oxides and the reducing agents are gradually heated during transport.
  • inlet opening 30 In the side walls of the deck furnace 10 - usually in the upper third - at least one inlet opening 30 is provided, through which reducing agents are introduced in the case where they have not already been introduced into the deck furnace 10 together with the metal oxides. Through this inlet opening 30, either all or additional reducing agents can be introduced into the deck oven 10.
  • These reducing agents can be in gaseous form as well as in liquid or solid form.
  • These reducing agents are, for example, carbon monoxide, hydrogen, natural gas, petroleum and petroleum derivatives, or solid carbon carriers such as lignite coke, petroleum coke, blast furnace dust, coal, or the like.
  • the reducing agent, in this case coal, which is introduced to a floor further down in the deck furnace 10, is mixed there by the rakes 26 with the heated metal oxides. Due to the high temperature and the presence of reducing agent, the metal oxides are gradually reduced to metal during transport through the deck oven 10.
  • nozzles 30 are provided for blowing in hot (250 ° C. to 500 ° C.) oxygen-containing gases, through which air or another oxygen-containing gas can be introduced into the deck oven 10. Due to the high temperatures and the presence of oxygen, it is possible to burn the combustible gases in the upper floors 12 of the deck furnace 10 and to use the resulting energy to dry the metal oxides and the reducing agents.
  • a gaseous reducing agent e.g. Carbon monoxide or hydrogen is provided through special nozzles 44.
  • the reduction of the metal oxides can be completed in this atmosphere with an increased reduction potential.
  • the metal produced is then discharged through the outlet 46 in the bottom 18 of the deck furnace 10 together with the ash.
  • the metal discharged at the outlet 46 is cooled in a cooling device 48 with the ash and, if appropriate, still usable reducing agents.
  • the reduced metal is then separated from the ashes of the reducing agents and, if appropriate, further reducing agents 52 by a separating device 50.
  • the gas mixture from the deck furnace 10 passes through the exhaust 20 into an afterburner 54, where the combustible gases of the gas mixture are burned.
  • the gas mixture is then introduced into a cooling device 56 to which a cooling medium is applied and cooled.
  • the cooled gas mixture is then cleaned using a cyclone filter 58 before it is discharged to the outside.
  • pressure locks must of course be provided at the openings 22, 30 for the input of the metal oxides and the reducing agents as well as on the fume cupboard 20.
  • the bearings of the shaft 24 must also be sealed and the outlet 46 must be provided with a lock for discharging hot material.
  • the exhaust gases from the deck furnace 10 can also be used to drive a turbine that generates electrical power.
  • This deck furnace 10 allows iron ore, zinc ores, wastes containing oil and iron oxide, and various problem wastes, such as dusts contaminated with iron oxides and / or other heavy metal oxides, to be used.
  • iron oxide-containing dusts or sludges from electrical or converter steelworks which contain hardly any carbon, or dust from the exhaust gas cleaning of blast furnaces, can be introduced into the deck furnace 10 through a special opening 30.
  • solid, liquid and gaseous reducing agents at various points in the deck furnace 10 and through the possibility of suctioning off excess gases at critical points, it is possible to control the reduction of the residues precisely and to carry out the process under optimal conditions.
  • the small volume of gas with a relatively high content of heavy metals can then be cleaned separately. Due to the small amounts of exhaust gas, low gas velocities occur on the corresponding floors, and so little dust is discharged with this exhaust gas. This results in a very high concentration of heavy metals in the exhaust gas.
  • the combustible gases of the withdrawn gas mixture are burned in an afterburner 66.
  • the remaining part of the gas mixture is cooled in a cooling device 68 and then cleaned with the aid of a cyclone filter 70 before it gets outside.
  • the iron oxide contained in the dusts is reduced to iron with the waste containing oil and iron oxide.
  • All rising gases including the volatile constituents of the reducing agents, can be completely burned outside the deck oven in the drying plant for the residues containing heavy metal and iron oxide and, if applicable, for the reducing agents, and the residual heat of the exhaust gases from the deck oven can be optimally used.
  • FIG. 2 shows a schematic representation of a tier of the deck oven 10 in which heating resistors 72, 74 are attached to the side wall or jacket 14 and below a tier 12.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Manufacture Of Iron (AREA)
  • Furnace Charging Or Discharging (AREA)
  • Furnace Details (AREA)

Abstract

The invention relates to a method for producing directly reduced metal in a multi-tiered furnace, whereby metal oxides and a reducing agent are inserted into the furnace and the process heat required for the reduction of the metal oxides is generated by indirect heating of the individual tiers of said furnace.

Description

Verfahren zum Herstellen von direkt reduziertem Metall in einem Process for producing directly reduced metal in one
Etagenofen.Deck oven.
Die vorliegende Erfindung betrifft ein Verfahren zum Herstellen von direkt reduziertem Metall in einem Etagenofen.The present invention relates to a method for producing directly reduced metal in a deck oven.
Etagenofen werden zum Herstellen von Metallen aus den entsprechendenMulti-deck furnaces are used to manufacture metals from the corresponding
Metalloxiden eingesetzt, wobei ein Metalloxid und ein Reduktionsmittel in den Etagenofen eingebracht werden und bei hoher Temperatur miteinander reagieren.Metal oxides are used, a metal oxide and a reducing agent being introduced into the deck oven and reacting with one another at high temperature.
Die Metalloxide und das Reduktionsmittel werden in den Etagenofen eingebracht und von Rechen die über die einzelnen Etagen ragen, umgewälzt und zum Rand der Etage befördert, von wo sie durch mehrere hierfür vorgesehene Öffnungen auf eine tiefergelegene Etage fallen. Von dort werden die mit Reduktionsmitteln vermischten Metalloxide zur Mitte der Etage befördert und fallen dann auf die darunterliegende Etage. Während des Transports von oben nach unten durch den Etagenofen werden die Metalloxide sowie die Reduktionsmittel nach und nach erhitzt.The metal oxides and the reducing agent are introduced into the deck furnace and raked by rakes that protrude over the individual floors and conveyed to the edge of the floor, from where they fall through a number of openings provided on a lower level. From there, the metal oxides mixed with reducing agents are transported to the middle of the floor and then fall to the floor below. During the transport from top to bottom through the deck oven, the metal oxides and the reducing agents are gradually heated.
Da die Reduktion von Metalloxiden endotherm ist, muß eine relativ hohe Ener- giemenge aufgewendet werden um die Reaktionen auszulösen und in Gang zu halten. Um dies zu erreichen wird der Etagenofen mit Gasbrennern o.a. aufgeheizt und ein Teil des Reduktionsmittels - im allgemeinen der flüchtige Teil eines Kohlestoffträgers wie z.B. Kohle - wird durch Einblasen von einem sauerstoffhal- tigen Gas im Etagenofen verbrannt. Durch die Verbrennung der Kohle und die Gasbrenner wird die benötigte Prozesswärme erzeugt und es entsteht Kohlendioxid. Ab einer bestimmten Temperatur reagiert das in den heißen Gasen enthaltene Kohlendioxyd mit dem Kohlenstoff im Etagenofen um Kohlenmonoxid gemäß dem Boudoirschen Gleichgewicht zu bilden. Das so gebildete Kohlenmonoxid reduziert die Metalloxide zu Metall. Der Kohlenmonxidgehalt der Gase im Eta- genofen bestimmt im wesentlichen das Reduktionspotential. Ein Nachteil dieses Verfahrens besteht darin, daß oxidierte Gase und Sauerstoff in den Etagenofen eingeführt werden, wo eine Reduktion stattfinden soll. Weiterhin fällt eine hohe Menge von Abgasen an die behandelt werden muß.Since the reduction of metal oxides is endothermic, a relatively high amount of energy has to be used to trigger the reactions and keep them going. To achieve this, the deck oven is heated with gas burners or the like and part of the reducing agent - generally the volatile part of a carbon carrier such as coal - is burned in the deck oven by blowing in an oxygen-containing gas. The process heat required is generated by burning the coal and the gas burners, and carbon dioxide is produced. From a certain temperature, the carbon dioxide contained in the hot gases reacts with the carbon in the deck oven to form carbon monoxide according to the Boudoir equilibrium. The carbon monoxide thus formed reduces the metal oxides to metal. The carbon monoxide content of the gases in the stage furnace essentially determines the reduction potential. A disadvantage of this method is that oxidized gases and oxygen are introduced into the deck oven where reduction is to take place. Furthermore, a large amount of exhaust gases falls to be treated.
In dieser Art von Etagenofen, der mit Hilfe einer heißen Flamme auf Erdgasbasis aufgeheizt wird, ist es schwierig ein homogenes Temperaturprofil zu erzeugen und aufrecht zu erhalten. Da die verschiedenen Zonen bzw. Etagen miteinander verbunden sind, ist es schwierig die Bedingungen in den einzelnen Zonen unabhängig voneinander zu beeinflussen. Die Gase, die eine Etage verlassen beeinflussen nämlich die Bedingungen auf der nächsten, oberen Etage. Aufgabe der vorliegenden Erfindung ist es folglich, ein Verfahren zum Herstellen von direkt reduziertem Metall, das mit geringeren Gasmengen auskommt, vorzuschlagen.In this type of deck oven, which is heated with the help of a hot flame based on natural gas, it is difficult to generate and maintain a homogeneous temperature profile. Since the different zones or floors are connected to each other, it is difficult to influence the conditions in the individual zones independently of one another. The gases that leave one floor affect the conditions on the next upper floor. It is therefore an object of the present invention to propose a method for producing directly reduced metal which requires less gas.
Diese Aufgabe wird erfindungsgemäß gelöst durch ein Verfahren zum Herstehen von direkt reduzieriem Metal! in einem Etagenofen dadurch gekennzeichnet, daß Metalloxide und Reduktionsmittel in den Etagenofen eingeführt werden und die benötigte Prozesswärme zum Reduzieren der Metalloxide durch indirektes Beheizen einzelner Etagen des Eiagenofens erzeugt wird.This object is achieved according to the invention by a method for producing directly reduced metal! in a deck oven, characterized in that metal oxides and reducing agents are introduced into the deck oven and the process heat required to reduce the metal oxides is generated by indirectly heating individual floors of the egg oven.
Im erfindungsgemäßen Verfahren wird die Prozesswärme dem Etagenofen durch Strahlungsenergie zugeführt und nicht durch eine Verbrennung des Reduktions- mittels in situ oder durch Gasbrenner wie bei den bekannten Verfahren.In the method according to the invention, the process heat is supplied to the deck oven by radiation energy and not by combustion of the reducing agent in situ or by gas burners as in the known methods.
Ein wesentlicher Vorteil der Erfindung besteht darin, daß kein Sauerstoff oder andere oxidierte Gase in den Etagenofen eingeblasen werden müssen, um die benötigte Prozesswärme zu erzeugen. Die Menge der im Etagenofen zirkulierenden Gase wird dadurch wesentlich verringert. Es brauchen nur wesentlich kleinere Mengen an Abgas nachbehandelt zu werden, wodurch das Verfahren kostengünstiger wird.A major advantage of the invention is that no oxygen or other oxidized gases have to be blown into the deck oven in order to generate the required process heat. This significantly reduces the amount of gases circulating in the deck oven. Only much smaller amounts of exhaust gas need to be post-treated, which makes the process cheaper.
Weiterhin sind die Gasgeschwindigkeiten auf den einzelnen Etagen, bedingt durch die niedrigeren Gasmengen geringer. Weniger Staub wird aufgewirbelt und aus den Etagenofen ausgetragen. Da kein Sauerstoff oder andere oxidierte Gase in den Etagenofen eingeblasen werden, ist das Reduktionspotential der Gase innerhalb des Etagenofen höher als bei bekannten Etagenofen.Furthermore, the gas velocities on the individual floors are lower due to the lower gas quantities. Less dust is whirled up and removed from the deck oven. Since no oxygen or other oxidized gases are blown into the deck oven, the reduction potential of the gases within the deck oven is higher than with known deck ovens.
Gemäß einer ersten bevorzugten Ausführung werden die einzelnen Etagen unabhängig voneinander indirekt beheizt.According to a first preferred embodiment, the individual floors are indirectly heated independently of one another.
Weiterhin erlaubt es dieses Verfahren den Etagenofen und seinen Inhalt gleichmäßiger zu beheizen.Furthermore, this method allows the deck oven and its contents to be heated more evenly.
Das Verfahren kann unter einem Druck von 1 bis 5 bar ausgeführt werden wodurch der Etagenofen kompakter gestaltet werden kann. Zum indirekten Beheizen einzelner Etagen werden vorteilhaft elektrische Heizwiderstände verwendet werden.The process can be carried out under a pressure of 1 to 5 bar, which means that the deck oven can be made more compact. Electrical heating resistors are advantageously used for indirect heating of individual floors.
Zusätzlich zu den festen Reduktionsmitteln werden in einer Vorteilhaft Ausführung gasförmige Reduktionsmitte! eingesetzt.In addition to the solid reducing agents, gaseous reducing agents are advantageously used! used.
Bei den Metalioxiden handelt es sieh z.B. um Eisenerz, Zinkerze, öl- und eisen- oxidhaitige Abfälle, und verschiedene Problemabfälle, wie z.B. mit Zinkoxiden und/oder anderen Schwermetalioxiden kontaminierte, eisenoxidhaitige Stäube.The metal oxides are e.g. around iron ore, zinc ores, oil and iron oxide-containing wastes, and various problem wastes, e.g. iron oxide-containing dusts contaminated with zinc oxides and / or other heavy metal oxides.
Die Erfindung betrifft auch einen Etagenofen der mehrere übereinanderliegende Etagen umfaßt, zum Herstellen von direkt reduziertem Metall. Der erfindungsgemäße Etagenofen ist durch Mittel zum indirekten Beheizen einzelner Etagen die die benötigte Prozesswärme zum Reduzieren der Metalloxide erzeugen, gekennzeichnetThe invention also relates to a deck oven, which comprises several superposed floors, for producing directly reduced metal. The multi-level furnace according to the invention is characterized by means for indirect heating of individual levels which generate the process heat required to reduce the metal oxides
Der Etagenofen kann, zum Beispiel, durch elektrische Heizwiderstände, die innerhalb des Etagenofen angebracht sind auf die benötigte Temperatur gebracht und auf dieser Temperatur gehalten werden. Es ist demnach möglich die Temperatur auf jeder Etage gezielt einzustellen, ohne dadurch die Bedingungen auf den nächsten Etagen wesentlich zu beeinflussen. Im Gegensatz zu den traditionellen Etagenofen, können die Bedingungen auf den verschiedenen Etagen unabhängig von einander beeinflußt werden. Bei gleicher Kapazität und Gasgeschwindigkeiten auf den Etagen kann der Etagenofen zur Herstellung von direkt reduziertem Metall nach dem erfindungsgemäßen Verfahren kleiner sein als ein klassischer Etagenofen.The deck oven can, for example, be brought to the required temperature and kept at this temperature by means of electrical heating resistors which are fitted inside the deck oven. It is therefore possible to specifically set the temperature on each floor without significantly influencing the conditions on the next floors. In contrast to the traditional deck oven, the conditions on the different floors can be influenced independently of each other. With the same capacity and gas velocities on the levels, the level furnace for producing directly reduced metal can be smaller than a conventional level furnace using the method according to the invention.
Die indirekte Heizelemente können auf der Oberfläche und/oder unterhalb der einzelnen Etagen angebracht werden. Sie können aber auch an der Seitenwand angebracht werden.The indirect heating elements can be attached to the surface and / or below the individual floors. But they can also be attached to the side wall.
Besonders vorteilhaft ist dieses Verfahren bei der Direktreduktion von Eisenerz.This process is particularly advantageous in the direct reduction of iron ore.
Weitere vorteilhafte Ausgestaltungen sind in den Unteransprüchen aufgeführt.Further advantageous configurations are listed in the subclaims.
Im folgenden wird nun eine Ausgestaltung der Erfindung anhand der beiliegenden Figur beschrieben. Es zeigt:An embodiment of the invention will now be described with reference to the accompanying figure. It shows:
Fig.1 : einen Schnitt durch einen Etagenofen zum Herstellen von direkt reduziertem Metall,1: a section through a deck oven for producing directly reduced metal,
Fig.2: die schematische Anordnung der elektrischen Heizwiderstände in den Etagenofen. Die Fig. 1 zeigt einen Schnitt durch einen Etagenofen 10, der mehrere - in diesemFig.2: the schematic arrangement of the electrical heating resistors in the deck oven. Fig. 1 shows a section through a deck oven 10, the several - in this
Fall zwölf - übereinander liegende Etagen 12 aufweist. Diese freitragendenCase twelve - superimposed floors 12. These self-supporting
Etagen 12, sowie der Mantel 14, Deckel 16 und der Boden 18 des EtagenofensLevels 12, as well as the jacket 14, cover 16 and the bottom 18 of the deck oven
10 sind aus feuerfestem Material.10 are made of fireproof material.
Im Deckel 16 des Etagenofens 10 ist ein Abzug 20 vorgesehen, durch den die Gase aus dem Etagenofen 10 evakuiert werden können und eine Öffnung 22, durch die Metalloxide und das Reduktionsmitteln auf die oberste Etage aufgetragen werden kann. Die Metalloxide können aber auch getrennt von den Reduktionsmitteln weiter unten in Etagenofen 10 eingebracht werdenIn the cover 16 of the deck oven 10 there is a fume hood 20 through which the gases can be evacuated from the deck oven 10 and an opening 22 through which metal oxides and the reducing agent can be applied to the top floor. However, the metal oxides can also be introduced further below in the deck furnace 10 separately from the reducing agents
In der Mitte des Etagenofens ist eine Welle 24 angebracht, an der Rechen 26 befestigt sind, die über die jeweiligen Etagen 12 ragen. Die Welle 24 und die Rechen 26 sind luft- oder wassergekühlt.In the middle of the deck oven, a shaft 24 is attached, to which rakes 26 are attached, which protrude above the respective floors 12. The shaft 24 and the rake 26 are air or water cooled.
Die Rechen 26 sind so ausgelegt, daß sie das Material auf einer Etage von außen nach innen und dann auf der darunterliegenden Etage von innen nach außen wälzen, um so das Material von oben nach unten durch den Etagenofen 10 zu transportieren. Die Metalloxide werden entweder außerhalb des Etagenofens 10 mit festen Reduktionsmitteln wie z.B. Braunkohlekoks, Petrolkoks, oder Kohle vermischt und anschließend wird das Gemisch aus Metalloxiden und Reduktionsmittel auf die oberste Etage aufgetragen. Die Metalloxide können aber auch getrennt auf die oberste Etage aufgetragen und die festen Reduktionsmittel werden weiter unten durch eine Einlaßöffnung 30 im Mantel 14 in den Etagenofen 10 eingebracht.The rakes 26 are designed in such a way that they roll the material from the outside inwards on one floor and then from the inside out on the floor below, in order to transport the material through the deck oven 10 from top to bottom. The metal oxides are either mixed with solid reducing agents such as lignite coke, petroleum coke, or coal outside the deck furnace 10, and the mixture of metal oxides and reducing agent is then applied to the top floor. However, the metal oxides can also be applied separately to the top floor and the solid reducing agents are introduced further down through an inlet opening 30 in the jacket 14 into the deck oven 10.
Die Metalloxide können eventuell außerhalb des Etagenofens 10 vorgetrocknet werden bevor oder nachdem sie mit den festen Reduktionsmitteln vermischt werden.The metal oxides can possibly be pre-dried outside the deck oven 10 before or after they are mixed with the solid reducing agents.
Nachdem das Gemisch aus Metalloxiden und Reduktionsmitteln auf die erste Etage des Etagenofens 10 aufgetragen ist, wird es von den Rechen 26 umgewälzt und zum Rand der Etage befördert, von wo es durch mehrere hierfür vorgesehene Öffnungen 28 auf die darunterliegende Etage fällt. Von dort werden die mit Reduktionsmitteln vermischten Metalloxide zur Mitte der Etage befördert und fallen dann auf die darunterliegende Etage. Während des Transports werden die Metalloxide sowie die Reduktionsmittel nach und nach erhitzt.After the mixture of metal oxides and reducing agents has been applied to the first floor of the deck furnace 10, it is circulated by the rakes 26 and conveyed to the edge of the deck, from where it falls through a plurality of openings 28 provided therefor onto the floor below. From there, the metal oxides mixed with reducing agents are transported to the middle of the floor and then fall to the floor below. The metal oxides and the reducing agents are gradually heated during transport.
Während dieser Zeit werden den mit Reduktionsmitteln vermischten Metalloxide, durch den Kontakt mit der Etage 12 und den aufsteigenden warmen Gasen, Feuchtigkeit entzogen. Die obersten Etagen des Etagenofens 10 gehören somit zu der Trocknungs- und Vorwärmezone.During this time, moisture is removed from the metal oxides mixed with reducing agents through contact with the floor 12 and the rising warm gases. The top floors of the deck oven 10 thus belong to the drying and preheating zone.
In den Seitenwänden des Etagenofens 10 ist - normalerweise im oberen Drittel - mindestens eine Einlaßöffnung 30 angebracht, durch die Reduktionsmittel eingebracht werden im Fall wo sie nicht schon zusammen mit den Metalloxiden in den Etagenofen 10 eingebracht worden sind. Durch diese Einlaßöffnung 30 können entweder sämtliche oder aber zusätzliche Reduktionsmittel in den Etagenofen 10 eingetragen werden Diese Reduktionsmittel können sowohl gasförmig als auch in flüssiger oder fester Form vorliegen. Bei diesen Reduktionsmitteln handelt es sich beispielsweise um Kohlenmonoxid, Wasserstoff, Erdgas, Erdöl und Erdölderivate, oder um feste Kohlenstoffträger wie z.B. um Braunkohlekoks, Petrolkoks, Hochofenstaub, Kohle, o.a.. Das Reduktionsmittel, in diesem Fall Kohle, das auf eine weiter unten im Etagenofen 10 liegenden Etage eingebracht wird, wird dort durch die Rechen 26 mit den erhitzten Metalloxiden vermischt. Durch die hohe Temperatur und durch die Gegenwart von Reduktionsmittel werden die Metalloxide während des Transpor- tes durch den Etagenofen 10 nach und nach zu Metall reduziert.In the side walls of the deck furnace 10 - usually in the upper third - at least one inlet opening 30 is provided, through which reducing agents are introduced in the case where they have not already been introduced into the deck furnace 10 together with the metal oxides. Through this inlet opening 30, either all or additional reducing agents can be introduced into the deck oven 10. These reducing agents can be in gaseous form as well as in liquid or solid form. These reducing agents are, for example, carbon monoxide, hydrogen, natural gas, petroleum and petroleum derivatives, or solid carbon carriers such as lignite coke, petroleum coke, blast furnace dust, coal, or the like. The reducing agent, in this case coal, which is introduced to a floor further down in the deck furnace 10, is mixed there by the rakes 26 with the heated metal oxides. Due to the high temperature and the presence of reducing agent, the metal oxides are gradually reduced to metal during transport through the deck oven 10.
Durch die kontrollierte Eingabe von festen, flüssigen und gasförmigen Reduktionsmitteln an verschiedenen Stellen des Etagenofens 10 und durch die Möglichkeit, überschüssige Gase an kritischen Stellen abzusaugen, ist es möglich, die Reduktion der Metalloxide genau zu kontrollieren und das Verfahren unter optimalen Bedingungen durchzuführen.Through the controlled input of solid, liquid and gaseous reducing agents at various points in the deck furnace 10 and through the possibility of extracting excess gases at critical points, it is possible to control the reduction of the metal oxides precisely and to carry out the process under optimal conditions.
In der Seitenwand sind Düsen 30 zum Einblasen von heißen (250°C bis 500°C) sauerstoffhaltigen Gasen vorgesehen, durch die man Luft oder ein anderes sauerstoffhaltiges Gas in den Etagenofen 10 eingeben kann. Durch die hohen Temperaturen und durch die Gegenwart von Sauerstoff ist es möglich die brenn- baren Gase in den oberen Etagen 12 des Etagenofens 10 zu verbrennen und die daraus entstandene Energie zum Trocknen der Metalloxide und der Reduktionsmittel zu nutzen.In the side wall, nozzles 30 are provided for blowing in hot (250 ° C. to 500 ° C.) oxygen-containing gases, through which air or another oxygen-containing gas can be introduced into the deck oven 10. Due to the high temperatures and the presence of oxygen, it is possible to burn the combustible gases in the upper floors 12 of the deck furnace 10 and to use the resulting energy to dry the metal oxides and the reducing agents.
In der letzten oder in den beiden letzten Etagen ist die Zugabe eines gasförmigen Reduktionsmittels, z.B. Kohlenmonoxid oder Wasserstoff durch spezielle Düsen 44, vorgesehen. In dieser Atmosphäre mit erhöhtem Reduktionspotential kann die Reduktion der Metalloxide vervollständigt werden.The addition of a gaseous reducing agent, e.g. Carbon monoxide or hydrogen is provided through special nozzles 44. The reduction of the metal oxides can be completed in this atmosphere with an increased reduction potential.
Anschließend wird das erzeugte Metall durch den Auslaß 46 im Boden 18 des Etagenofens 10 zusammen mit der Asche ausgetragen.The metal produced is then discharged through the outlet 46 in the bottom 18 of the deck furnace 10 together with the ash.
Das am Auslaß 46 ausgetragene Metall wird mit der Asche und gegebenenfalls noch weiterverwertbaren Reduktionsmitteln in einer Abkühlvorrichtung 48 abgekühlt. Anschließend wird das reduzierte Metall über eine Abscheidevorrichtung 50 von der Asche der Reduktionsmittel und gegebenenfalls noch weiterverwertbaren Reduktionsmitteln 52 getrennt.The metal discharged at the outlet 46 is cooled in a cooling device 48 with the ash and, if appropriate, still usable reducing agents. The reduced metal is then separated from the ashes of the reducing agents and, if appropriate, further reducing agents 52 by a separating device 50.
Das Gasgemisch aus dem Etagenofen 10 gelangt durch den Abzug 20 in einen Nachbrenner 54, wo die brennbaren Gase des Gasgemischs verbrannt werden. Anschließend wird das Gasgemisch in eine mit einem Kühlmedium beaufschlagten Abkühlvorrichtung 56 eingetragen und abgekühlt. Das abgekühlte Gasgemisch wird anschließend mit Hilfe eines Zyklonfilters 58 gereinigt, bevor es nach außen abgeführt wird. Im Fall wo der Etagenofen 10 unter Überdruck gefahren wird, müssen natürlich Druckschleusen an den Öffnungen 22, 30 für die Eingabe von den Metalloxiden und den Reduktionsmittlen sowie am Abzug 20 vorgesehen sein. Die Lager der Welle 24 müssen auch abgedichtet und der Auslaß 46 mit einer Schleuse zu Austragen von heißem Material versehen sein. Die Abgase des Etagenofens 10 können aber auch dazu benutzt werden um eine Turbine die elektrische Strom erzeugt anzutreiben. In diesem Falle sollte auf eine Nachverbrennung innerhalb des Etagenofens 10 verzichtet werden und kein sauerstoffhaltiges Gas durch die Düsen 32 in den Etagenofen 10 eingebracht werden. Dieser Etagenofen 10 erlaubt es, Eisenerz, Zinkerze, öl- und eisenoxidhaltigen Abfälle, und verschiedene Problemabfälle, wie z.B. mit Zinkoxiden und/oder anderen Schwermetalloxiden kontaminierte, eisenoxidhaltige Stäube zu verwerten.The gas mixture from the deck furnace 10 passes through the exhaust 20 into an afterburner 54, where the combustible gases of the gas mixture are burned. The gas mixture is then introduced into a cooling device 56 to which a cooling medium is applied and cooled. The cooled gas mixture is then cleaned using a cyclone filter 58 before it is discharged to the outside. In the case where the deck furnace 10 is operated under excess pressure, pressure locks must of course be provided at the openings 22, 30 for the input of the metal oxides and the reducing agents as well as on the fume cupboard 20. The bearings of the shaft 24 must also be sealed and the outlet 46 must be provided with a lock for discharging hot material. The exhaust gases from the deck furnace 10 can also be used to drive a turbine that generates electrical power. In this case, post-combustion within the deck oven 10 should be avoided and no oxygen-containing gas should be introduced through the nozzles 32 into the deck oven 10. This deck furnace 10 allows iron ore, zinc ores, wastes containing oil and iron oxide, and various problem wastes, such as dusts contaminated with iron oxides and / or other heavy metal oxides, to be used.
So können eisenoxidhaltige Stäube oder Schlämme aus Elektro- oder Konverter- Stahlwerken, die ja kaum Kohlenstoff enthalten, oder Staub aus der Abgasreinigung von Hochöfen, durch eine spezielle Öffnung 30 in den Etagenofen 10 eingebracht werden. Durch die kontrollierte Eingabe von festen, flüssigen und gasförmigen Reduktionsmitteln an verschiedenen Stellen des Etagenofens 10 und durch die Möglichkeit, überschüssige Gase an kritischen Stellen abzusaugen, ist es möglich, die Reduktion der Reststoffe genau zu kontrollieren und das Verfahren unter optimalen Bedingungen durchzuführen.For example, iron oxide-containing dusts or sludges from electrical or converter steelworks, which contain hardly any carbon, or dust from the exhaust gas cleaning of blast furnaces, can be introduced into the deck furnace 10 through a special opening 30. Through the controlled input of solid, liquid and gaseous reducing agents at various points in the deck furnace 10 and through the possibility of suctioning off excess gases at critical points, it is possible to control the reduction of the residues precisely and to carry out the process under optimal conditions.
Da diese eisenoxidhaltigen Stäube oder Schlämme oft durch Schwermetalloxide verseucht sind, kann man einen Großteil der Gase, die im Etagenofen nach oben strömen unterhalb der Etage, auf die die schwermetalloxidhaltigen Stäube oder Schlämme aufgetragen werden, durch einen Absaugstutzen 60 in der Seitenwand aus dem Etagenofen 10 absaugen und oberhalb dieser Etage durch einen Einlaß 62 wieder in den Etagenofen 10 einblasen. Dadurch ist die auf den Etagen, auf die die schwermetalloxidhaltigen Stäube oder Schlämme eingebracht werden, vorhandene Gasmenge gering. Die Schwermetalloxide, die in den Stäuben oder Schlämme enthalten sind, werden nach ihrer Einbringung in den Etagenofen reduziert und die gebildeten Metalle verflüchtigen sich. Sie können dann in einer relativ geringen Gasmenge auf diesen Etage durch einen Auslaß 64 in der Seitenwand aus dem Etagenofen 10 abgesaugt werden.Since these iron oxide-containing dusts or sludges are often contaminated by heavy metal oxides, a large part of the gases that flow upwards in the deck oven below the floor to which the dusts or sludges containing heavy metal oxide are applied can be extracted from the deck oven 10 through a suction port 60 in the side wall vacuum and above this floor through an inlet Blow 62 back into the deck oven 10. As a result, the amount of gas present on the floors to which the heavy metal oxide-containing dusts or sludges are introduced is small. The heavy metal oxides that are contained in the dusts or sludges are reduced after their introduction into the deck oven and the metals formed evaporate. You can then be sucked out of the deck oven 10 in a relatively small amount of gas on this floor through an outlet 64 in the side wall.
Das geringe Volumen an Gas mit relativ hohem Gehalt an Schwermetallen kann dann getrennt gereinigt werden. Durch die geringen Abgasmengen ergeben sich auf den entsprechenden Etagen niedrige Gasgeschwindigkeiten und so wird wenig Staub mit diesem Abgas ausgetragen. Dadurch ergibt sich eine sehr hohe Schwermetallkonzentration im Abgas.The small volume of gas with a relatively high content of heavy metals can then be cleaned separately. Due to the small amounts of exhaust gas, low gas velocities occur on the corresponding floors, and so little dust is discharged with this exhaust gas. This results in a very high concentration of heavy metals in the exhaust gas.
Die brennbaren Gase des abgezogenen Gasgemischs werden in einem Nachbrenner 66 verbrannt. Der restliche Teil des Gasgemischs wird in einer Abkühlvor- richtung 68 abgekühlt und anschließend mit Hilfe eines Zyklonfilters 70 gereinigt, bevor es nach außen gelangt.The combustible gases of the withdrawn gas mixture are burned in an afterburner 66. The remaining part of the gas mixture is cooled in a cooling device 68 and then cleaned with the aid of a cyclone filter 70 before it gets outside.
Das in den Stäuben enthaltene Eisenoxid wird mit den eingegebenen öl- und eisenoxidhaltigen Abfälle zu Eisen reduziert.The iron oxide contained in the dusts is reduced to iron with the waste containing oil and iron oxide.
Alle aufsteigenden Gase, inklusive der flüchtigen Bestandteile der Reduktions- mittel, können außerhalb des Etagenofens in der Trocknungsanlage für die schwermetall- und eisenoxidhaltigen Reststoffe und gegebenenfalls für die Reduktionsmittel komplett verbrannt werden und die Restwärme der Abgase des Etagenofens kann hierdurch optimal genutzt werden.All rising gases, including the volatile constituents of the reducing agents, can be completely burned outside the deck oven in the drying plant for the residues containing heavy metal and iron oxide and, if applicable, for the reducing agents, and the residual heat of the exhaust gases from the deck oven can be optimally used.
Fig. 2 zeigt eine schematische Darstellung einer Etage des Etagenofen 10 in der Heizwiderstände 72, 74 an der Seitenwand bzw. dem Mantel 14 und unterhalb einer Etage 12 angebracht sind. FIG. 2 shows a schematic representation of a tier of the deck oven 10 in which heating resistors 72, 74 are attached to the side wall or jacket 14 and below a tier 12.

Claims

PATENTANSPRÜCHE PATENT CLAIMS
1 . Verfahren zum Herstellen von direkt reduziertem Metall in einem Etagenofen dadurch gekennzeichnet, daß Metalloxide und Reduktionsmittel in den Etagenofen eingeführt werden und die benötigte Prozesswärme zum Reduzieren der Metalloxide durch indirektes Beheizen einzelner Etagen des Etagenofens erzeugt wird.1 . A process for producing directly reduced metal in a deck oven, characterized in that metal oxides and reducing agents are introduced into the deck oven and the process heat required to reduce the metal oxides is generated by indirectly heating individual floors of the deck oven.
2. Verfahren nach Anspruch 1 dadurch gekennzeichnet, daß die einzelnen Etagen unabhängig voneinander indirekt beheizt werden.2. The method according to claim 1, characterized in that the individual floors are independently heated indirectly.
3. Verfahren nach Anspruch 1 oder 2 dadurch gekennzeichnet, daß das Verfahren unter einem Druck von 1 bis 5 bar ausgeführt wird. 3. The method according to claim 1 or 2, characterized in that the method is carried out under a pressure of 1 to 5 bar.
4. Verfahren nach einem der vorhergehenden Ansprüche dadurch gekennzeichnet, daß zum indirekten Beheizen einzelner Etagen elektrische Heizwiderstände verwendet werden.4. The method according to any one of the preceding claims, characterized in that electrical heating resistors are used for indirect heating of individual floors.
5. Verfahren nach einem der vorhergehenden Ansprüchen dadurch gekennzeichnet, daß gasförmige Reduktionsmittel eingesetzt werden. 5. The method according to any one of the preceding claims, characterized in that gaseous reducing agents are used.
6. Verfahren nach einem der vorhergehenden Ansprüche dadurch gekennzeichnet, daß es sich bei den Metalloxiden um Eisenerz, Zinkerze, öl- und eisenoxidhaltigen Abfälle, und verschiedene Problemabfälle, wie z.B. mit Zinkoxiden und/oder anderen Schwermetalloxiden kontaminierte, eisenoxidhaltige Stäube handelt. 6. The method according to any one of the preceding claims, characterized in that the metal oxides are iron ore, zinc ores, oil and iron oxide-containing wastes, and various problem wastes, such as e.g. dusts contaminated with zinc oxides and / or other heavy metal oxides.
7. Etagenofen der mehrere übereinanderliegende Etagen umfaßt, zum Herstellen von direkt reduziertem Metall gekennzeichnet durch Mittel zum indirekten Beheizen einzelner Etagen die die benötigte Prozesswärme zum Reduzieren der Metalloxide erzeugen.7. deck oven which comprises a plurality of superposed floors, for producing directly reduced metal, characterized by means for indirectly heating individual floors which generate the process heat required to reduce the metal oxides.
8. Etagenofen nach Anspruch 7 dadurch gekennzeichnet, daß elektrische Heizwiderstände innerhalb des Etagenofens angebracht sind.8. deck oven according to claim 7, characterized in that electrical heating resistors are attached within the deck oven.
9. Etagenofen nach Anspruch 7 oder 8 dadurch gekennzeichnet, daß elektrische Heizwiderstände unterhalb und/oder auf einzelnen Etagen angebracht sind. 9. deck oven according to claim 7 or 8, characterized in that electrical heating resistors are attached below and / or on individual floors.
10. Etagenofen nach einem der Ansprüche 8 oder 9 dadurch gekennzeichnet, daß die elektrischen Heizwiderstände an einer Seitenwand des Etagenofens angebracht sind.10. deck oven according to one of claims 8 or 9, characterized in that the electrical heating resistors are attached to a side wall of the deck oven.
11. Etagenofen nach einem der Ansprüche 8 bis 10 dadurch gekennzeichnet, daß die elektrischen Heizwiderstände eine Schutzummantelung aufweisen. 11. deck oven according to one of claims 8 to 10, characterized in that the electrical heating resistors have a protective jacket.
EP99947270A 1998-09-23 1999-08-30 Method for producing directly reduced metal in a multi-tiered furnace Withdrawn EP1115890A1 (en)

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LU90291A LU90291B1 (en) 1998-09-23 1998-09-23 Process for producing directly reduced metal in a deck oven
PCT/EP1999/006381 WO2000017404A1 (en) 1998-09-23 1999-08-30 Method for producing directly reduced metal in a multi-tiered furnace

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WO2004057038A1 (en) 2002-12-23 2004-07-08 Posco An apparatus for manufacturing moltens irons to improve operation of fluidized bed type reduction apparatus and manufacturing method using the same
EP1905853A1 (en) 2006-09-29 2008-04-02 Paul Wurth S.A. Heat treatment method of metal-containing waste materials contaminated with organics and apparatus therefor
LU91312B1 (en) * 2007-02-16 2008-08-18 Wurth Paul Sa Multiple hearth furnace
JP5601138B2 (en) * 2010-10-14 2014-10-08 新日鐵住金株式会社 Heating method for agglomerates
DE102016120833A1 (en) * 2016-11-02 2018-05-03 Thyssenkrupp Ag Multi-level oven and method for operating a multi-level oven

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FR717429A (en) * 1930-12-03 1932-01-08 Trent Process Corp Direct reduction process for iron ore
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DE2134977A1 (en) * 1971-07-13 1973-01-25 Atsukawa Masami Solid state iron prodn from powder or granule ore - by high intensity alternating current resistance heating
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