Metallurgical apparatus – With means treating or handling gases exhausted by treating...
Reexamination Certificate
1999-06-15
2001-11-13
Andrews, Melvyn (Department: 1742)
Metallurgical apparatus
With means treating or handling gases exhausted by treating...
C266S182000
Reexamination Certificate
active
06315943
ABSTRACT:
The invention relates to a method of producing molten metal, in particular pig iron or steel pre-products, from at least partially fine-particulate metal carriers, in particular partially reduced or reduced sponge iron, in a melter gasifier in which under supply of carbon-containing material and oxygen or an oxygen-containing gas under simultaneous formation of a reducing gas in a bed formed of solid carbon carriers the metal carriers are melted, optionally upon previous complete reduction, as well as to a melter gasifier for carrying out the method.
From EP-B-0 010 627 it is known to feed in particulate iron-containing material, such as pre-reduced sponge iron, through a centrally arranged charging opening in the hood of the melter gasifier from above, with the particles dropping into the melter gasifier by the effect of gravity and being slowed down in the fluidized bed existing within the melter gasifier. Coal in lumpy form is charged through a charging opening arranged laterally in the hood of the melter gasifier or in the dome terminating the melter gasifier toward the top, also under the influence of gravity. The reducing gas formed in the melter gasifier is withdrawn through the centrally arranged charging opening for the iron-containing material.
A process of this kind is not suitable for processing fine-particle metal carriers, in particular fine-particle sponge iron, since the fine-particle metal carriers due to the pronounced gas flow of the reducing gas formed in the gasification zone and withdrawn through the central charging opening arranged in the hood or in the dome of the melter gasifier would be instantly carried out of the melter gasifier. Such a discharge of the fine-particle metal carriers is further favored by the temperature reigning in the upper region of the melter gasifier, i.e. in the region above the gasification zone, which is too low to ensure a melt-down, i.e. agglomeration of the fine particles at the charging site to form bigger particles which in spite of the ascending gas stream could sink down into the gasification zone.
From EP-A-0 217 331 it is known to introduce pre-reduced fine ore into a melter gasifier and to completely reduce and melt it by means of a plasma burner while supplying a carbon-containing reducing agent. The pre-reduced fine ore or the sponge-iron powder respectively is fed to a plasma burner provided in the lower section of the melter gasifier. A disadvantage of this method is that by supplying the pre-reduced fine ore directly in the lower meltdown region, i.e. in the region where the melt collects, complete reduction can no longer be ensured and the chemical composition necessary for further processing the pig iron cannot be achieved by any means. Moreover, the charging of major amounts of pre-reduced fine ore is not feasible due to fluidized bed or the fixed bed forming from coal in the lower region of the melter gasifier, as it is not possible to carry off a sufficient quantity of the melting products from the high-temperature zone of the plasma burner. The charging of major amounts of pre-reduced fine ore would lead to instant thermal and mechanical failure of the plasma burner.
From EP-B-0 11 1 176 it is known to feed a fine grain fraction of sponge iron particles into the melter gasifier through a downpipe projecting from the head of the melter gasifier into the proximity of the coal fluidized bed. At the end of the downpipe a baffle plate is provided for minimizing the velocity of the fine grain fraction, resulting in a very low exit velocity of the fine grain fraction from the downpipe. At the charging site, the temperature reigning in the melter gasifier is very low, whereby immediate melting of the supplied fine grain fraction is prevented. This and the low exit velocity from the downpipe cause a substantial portion of the supplied fine grain fraction to be carried out of the melter gasifier again together with the reducing gas generated in the same. The charging of a major amount of sponge iron particles containing a fine portion or of only a fine grain fraction is not feasible in accordance with this method.
From EP-A-0 594 557 it is known to charge a fine grain fraction of sponge iron by means of a conveying gas directly into the fluidized bed formed by the gasification zone in the melter gasifier. However, this is disadvantageous, since hereby the gas circulation of the fluidized bed may be disturbed because obstructions of the fluidized bed, which acts like a filter, may ensue as a consequence of the fine grain fraction that is blown directly into the fluidized bed. As a result, eruptive outbreaks of gas may occur which will break up the clogged fluidized bed. Hereby, the gasification process for the carbon carriers and also the melt-down process for the reduced iron ore are markedly disturbed.
From EP-A-0 576 414 it is known to feed fine-particle metal carriers into the gasification zone via dust burners. This method exhibits a poor melt-in performance, which is due to a short dwelling time of the particles in the hot flame.
The invention aims at avoiding these disadvantages and difficulties and has as its object to provide a method of the kind initially described as well as a melter gasifier for carrying out the method, allowing the processing of fine-particulate metal carriers without the need for briquetting and, in doing so, on the one hand to reliably avoid discharging of the supplied fine-particulate metal carriers, optionally in pre-reduced or in completely reduced condition, by the reducing gas produced in the melter gasifier, and on the other hand to ensure complete reduction, which may optionally be required, of the fine particles. It is a particular object of the invention to provide a method enabling the processing of a charge the greatest part, preferably 100%, of which is/are made up of fine-particulate iron-containing material to pig iron and/or steel prematerial utilizing a melter gasifier.
With a method of the initially described kind, this object is achieved in that the fine-particulate metal carriers are charged to a high-temperature combustion zone maintained by a combustion process and there, optionally upon complete reduction, are melted at least for the most part or completely, wherein the high-temperature combustion zone is spatially isolated from the freeboard of the melter gasifier located above the bed and extends into the bed, wherein the offgases formed in the high-temperature combustion zone exit the same passing through at least a portion of the bed and wherein furthermore the offgases are cooled in the bed and are withdrawn from the melter gasifier along with the reducing gas formed within the bed.
A melter gasifier for carrying out the method, having feed ducts for oxygen-containing gases, carbon carriers and metal carriers running into it and having at least one gas discharge duct for a reducing gas produced in a bed of the melter gasifier formed of solid carbon carriers departing from it, and with a tap for the metal melt and for slag is characterized in that at least one feed duct for feeding fine-particulate metal carriers opens into at least one high-temperature combustion chamber that is spatially isolated from the interior of the melter gasifier and, by a mouth, in turn projects into the bed formed of solid carbon carriers and is provided with a burner.
To assure easy access to the high-temperature combustion chamber as well as a long service life of the same, the high-temperature combustion chamber is advantageously constructed as a wall that departs from the dome of the melter gasifier, is open at the bottom, cylindrical in shape and provided with a refractory material.
A simple construction is characterized in that only a single high-temperature combustion chamber is provided which is arranged centrally and with its longitudinal axis lying in the vertical longitudinal axis of the melter gasifier.
Advantageously, the high-temperature combustion chamber by its upper end projects outward through the dome of the melter gasifier and at this exterior end the feed duct
Andrews Melvyn
Ostrolenk Faber Gerb & Soffen, LLP
Voest-Alpine Industriean-lagenbau GmbH
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