Plant and process for the production of pig iron and/or sponge i

Details Plant and process for the production of pig iron and/or sponge i Plant and process for the production of pig iron and/or sponge i

1997-04-17

1999-11-23

Andrews, Melvyn

Specialized metallurgical processes, compositions for use therei

Processes

Producing or treating free metal

75446, 266160, 266172, C21B 1314

Patent

active

059893087

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a plant for the production of pig iron and/or sponge iron, comprising a direct-reduction shaft furnace for lumpy iron ore, a melter gasifier, a feed duct for a reducing gas connecting the melter gasifier with the shaft furnace, a conveying duct for the reduction product formed in the shaft furnace connecting the shaft furnace with the melter gasifier, a top-gas discharge duct departing from the shaft furnace, feed ducts for oxygen-containing gases and carbon carriers running into the melter gasifier and a tap for pig iron and slag provided at the melting vessel. Furthermore, the invention relates to a process for producing pig iron and/or sponge iron using this plant.
A plant of this type is known, for instance, from AT-B - 376.241 as well as from DE-C - 40 37 977. There, lumpy iron ore is reduced to sponge iron in a shaft furnace in a fixed-bed direct reduction zone. The sponge iron subsequently is melted in the melter gasifier in a meltdown gasifying zone under supply of carbon carriers and oxygen-containing gas. In the melter gasifier, a CO and H.sub.2 -containing reducing gas is produced, which is fed to the direct reduction zone of the shaft furnace via the feed duct connecting the melter gasifier with the shaft furnace, is reacted there and is drawn off as a top gas. In practice, that plant and process have proved successful for processing lumpy iron ore, by which ore having a grain size of above 3 mm, preferably above 6 mm, is understood.
The invention is based on the object to provide a plant as well as a process, by which not only lumpy ore, but also fine ore can be processed, in particular fine ore having a grain size of between 0 and 8 mm, preferably between 0 and 4 mm. In particular, it is to be feasible to widely vary the charging amount of lumpy ore and fine ore in proportion to the overall charging amount of ore while being able to operate the plant in a manner optimized in terms of energy and product over a wide range of the ratio of lumpy ore to fine ore amounts. This means that the product produced, i.e., pig iron and/or sponge iron, complies with a high quality standard at a minimum energy input, in particular exhibits a high degree of metallization and purity, such that further processing will be ensured without any problems.
With a plant of the initially defined kind, this object is achieved by at least one fluidized bed reactor intended to receive fine ore, a reducing-gas feed duct leading to said fluidized bed reactor, an offgas discharge duct departing from the fluidized bed reactor and a discharge means, preferably a briquetting means, provided for the reduction product formed in the fluidized bed reactor, wherein the top-gas discharge duct of the shaft furnace and the offgas discharge duct of the fluidized bed reactor run into a purification means, such as a scrubber, and subsequently into a heating means from which the reducing-gas feed duct of the fluidized bed reactor departs.
The processing of fine ore to sponge iron in a fluidized bed reactor, in principle, is known from U.S. Pat. No. 5,082,251. There, the reducing gas is produced by catalytic reformation of desulphurized and preheated natural gas with overheated water vapor in a reformer furnace. That process allows for the production of high-quality sponge iron, yet exclusively from fine ore.
By the combination according to the invention, of a shaft furnace plant as initially described with a fluidized bed reactor thereby forming a portion of the reducing gas fed to the fluidized bed reactor by the reducing gas produced in the melter gasifier and reacted to top gas in the shaft furnace, it is feasible to operate the plant at an optimum utilization of the energy from the energy carriers supplied, wherein the quantitative portion of fine ore or lumpy ore in the overall charging amount is variable within wide ranges even with an operation using exclusively fine ore being conceivable. Thus, according to the invention the amount of the ore type available in each respective case, i.e., fine ore or lumpy o

REFERENCES:
patent: 5082251 (1992-01-01), Whipp
patent: 5185032 (1993-02-01), Whipp
patent: 5238487 (1993-08-01), Hauk et al.
patent: 5534046 (1996-07-01), Kepplinger et al.
patent: 5535991 (1996-07-01), Kepplinger et al.
patent: 5676732 (1997-10-01), Viramontes-Brown et al.

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