Process for the production of molten pig iron or steel pre-produ

Details Process for the production of molten pig iron or steel pre-produ Process for the production of molten pig iron or steel pre-produ

1997-04-17

1999-09-07

Andrews, Melvyn

Specialized metallurgical processes, compositions for use therei

Processes

Producing or treating free metal

75445, 266172, 266182, C21B 1300

Patent

active

059481390

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for the production of molten pig iron or steel pre-products from fine-particulate iron-containing material, in particular reduced sponge iron, in a meltdown-gasifying zone of a melter gasifier, in which, under the supply of carbon-containing material and oxygen-containing gas at the simultaneous formation of a reducing gas, in a bed formed of solid carbon carriers, the iron-containing material is melted when passing the bed, optionally upon previous complete reduction, and a plant for carrying out the process.
EP-B-0 010 627 teaches a process for the production of molten pig iron or steel pre-products from particulate iron-containing material, particularly prereduced sponge iron, and for the production of reducing gas in a melter gasifier, wherein by the addition of coal and by blowing in an oxygen-containing gas a fluidized bed is formed of coke particles. Here, the oxygen-containing gas or pure oxygen respectively are injected into the lower region of the melter gasifier. The particulate iron-containing material, particularly prereduced sponge iron, and the lumpy coal are fed in from above, through charging openings arranged in the hood of the melter gasifier, the descending particles are slowed down in the fluidized bed and the iron-containing particles are reduced and melted while falling through the coke fluidized bed. The molten and slag-covered metal collects at the bottom of the melter gasifier. Metal and slag are drawn off through separate tap openings.
A process of this kind is, however, not suited for processing fine-particle sponge iron, as fine-particle sponge iron would be discharged from melter gasifier at once, due to the pronounced gas flow existing within the same. Discharging is further promoted by the temperature reigning in the upper region of the melter gasifier, since it is too low to ensure melting of the sponge iron at the charging site.
From U.S. application Ser. No. 5,082,251 it is known to directly reduce iron-containing fine ore in a fluidized bed operation by means of a reducing gas produced from natural gas. In this process the fine ore, which is rich in iron, is reduced by means of a reducing gas, at elevated pressure, in a system of fluidized bed reactors arranged in series. The sponge iron powder thus obtained is subsequently subjected to hot or cold briquetting. For further processing the sponge iron powder, separate melting facilities have to be provided.
From EP-A-0 217 331 it is known to directly prereduce fine ore in a fluidized bed operation and to feed the prereduced fine ore to a melter gasifier and to completely reduce it by means of a plasma burner under the supply of a carbon-containing reducing agent and to melt it. In the melter gasifier, a fluidized bed forms and thereabove a fluidized bed of coke. The prereduced fine ore or the sponge iron powder respectively are supplied to a plasma burner provided in a lower section of the melter gasifier. One disadvantage here is that by feeding the prereduced fine ore immediately in the lower melting region, i.e. in the region where the melt collects, complete reduction is no longer ensured and the chemical composition required for further processing of the pig iron cannot be achieved in any event. Moreover, charging of substantial amounts of prereduced fine ore is not feasible, due to the fluidized bed or fixed bed respectively forming from coal in the lower region of the melter gasifier, as it is not feasible to discharge a sufficient portion of the melting products from the high-temperature zone of the plasma burner. Charging of more substantial amounts of prereduced fine ore would instantly lead to thermal and mechanical failure of the plasma burner.
From EP-B-0 111 176 it is known to produce sponge iron particles and molten pig iron from lumpy iron ore, the iron ore being directly reduced in a direct-reduction aggregate and sponge iron particles discharged from the direct-reduction aggregate being fractionated into a coarse-and fine-grain fraction. The fine-grain fraction is suppli

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