Method and apparatus for producing molten iron

Abstract

A system for producing molten iron from iron ores, including a direct reduction shaft furnace, a melting zone in a melting furnace having a coke bed in its lower portion and a charging and preheating chamber in its upper portion, and at least one reducing gas generation zone in communication with said melting zone.

Description

RELATED APPLICATIONS / PATENTS & INCORPORATION BY REFERENCE [0001] A claim of priority is made to U.S. Provisional Application No. 60 / 507,160, filed Sep. 30, 2003.[0002] Each of the applications and patents cited in this text, as well as each document or reference cited in each of the applications and patents (including during the prosecution of each issued patent; “application cited documents”), and each of the PCT and foreign applications or patents corresponding to and / or claiming priority from any of these applications and patents, and each of the documents cited or referenced in each of the application cited documents, are hereby expressly incorporated herein by reference. More generally, documents or references are cited in this text, either in a Reference List before the claims, or in the text itself; and, each of these documents or references (“herein-cited references”), as well as each document or reference cited in each of the herein-cited references (including any manufactu...

AI Technical Summary

Benefits of technology

[0018] It is a further object of the invention to provide an improved system for producing molten iron adapted for its installation in conjunction with existing direct reduction plants, in order to substitute and efficiently utilize fuels having a lower cost that natural gas and therewith produce high quality pig-iron.

[0019] It is still another object of the invention to provide an improved system for producing molten iron adapted for its installation in electric furnace steel-making facilities, in order to charge molten metal to said electric furnaces and reduce electricity consumption as well as increasing their productivity.

Problems solved by technology

Blast furnaces, however, require costly coke.

This has several drawbacks, not the least of which is that coking coal is not found throughout the world.

Thus, in many instances it must be imported at great cost to the iron producer.

Along with the cost associated with transforming coal into coke, coking plants are not considered environmentally friendly under new pollution regulations in many countries.

But to date, these processes have failed to provide an operational plant capable of producing molten iron at competitive prices when compared with blast furnaces or with combined direct reduction and electric furnace facilities.

Hot reducing gases and powdered carbon are introduced toward a molten iron bath in the melting portion of the furnace, Stift's process however requires additional heat to be provided to the hot gases besides the heat produced by the partial combustion, and the integration of the reduction shaft with the melting furnace does not allow for providing the optimal conditions for the three main processes involved, namely: reduction of ores, melting of reduced ores and production of reducing gases.

For example, since the oxidation reactions of the fuel take place inside the melting furnace, some of the reactants may react with the bed of coke and consume the coke.

Coke consumption causes an increase in operation costs both because of cost and because replenishment of the consumed coke requires special openings or operations in the use of the melting furnace.

However, this process does not separate the gas generation zone and equipment from the melting furnace.

This patent presents a separate chamber for partial combustion but presents a significant disadvantage because said chamber is located inside the melting furnace with considerable cost for special materials and design so that the structure withstands the high-temperature environment within said furnace.

Yet another process, which has been in operation for years, separates the reduction shaft furnace from the melting furnace but presents the disadvantage of forming a reaction chamber above the molten iron bath for combusting coal and producing heat and reducing gases which are utilized in the reduction furnace.

Although this process is successful in not using coke, it however presents a great disadvantage of producing an excess of reducing gases that must be used for some other purposes, for example, electricity generation or for heating purposes.

This process considered alone is not competitive and therefore its use has not spread as originally expected.

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