Specialized metallurgical processes – compositions for use therei – Processes – Electrothermic processes
Patent
1987-03-23
1989-05-30
Kastler, S.
Specialized metallurgical processes, compositions for use therei
Processes
Electrothermic processes
75 29, 266142, C21B 1314
Patent
active
048347914
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for producing raw iron from iron concentrates and for the manufacture of gas.
The invention also relates to plant apparatus for carrying out the method.
A reactor for producing gas and also a certain amount of raw iron in conjunction therewith is known from Swedish Patent Specification No. 7706876-5. In this Swedish patent specification there is described a method for producing a gaseous mixture of primarily carbon monoxide (CO) and hydrogen gas (H.sub.2) from coal which contains a certain amount of water. When practising this known method, coal is injected into a molten metal bath in quantities which are stoichiometrically excessive in relation to the oxygen injected into the bath in the form or iron oxides, at the same time as gaseous oxygen is injected so as to oxidize the coal excess. Thus, although the method relates to the manufacture of gas a significant quantity of iron is also produced.
The Swedish Patent Specification No. 8103201-3 also describes a method for the gasification of coal, in which a reactor is used. According to this patent specification coal, oxygen gas and iron oxides are also charged to the reactor vessel, the iron oxides constituting a cooling medium. Coal is introduced into the molten bath in stoichiometric quantities in relation to the oxygen gas injected thereinto. The invention according to this patent resides in placing the reactor under an overpressure, thereby enabling a far greater quantity of gas to be produced, since a greater amount of coal an oxygen gas in relation to the size of the bath can be introduced thereinto than when atmospheric pressure prevails. According to this patent specification, the prime object of the invention is to increase the production of gas.
Thus, th aforementioned patent specification relate to gas manufacturing processes, where the object is to produce as much gas as possible. The fact that iron-bearing materials are also injected into the bath is simply because it is desired to convert the molten iron bath in a manner to prevent it becoming excessively contaminated with impurities introduced in the coal.
The Swedish Patent Specicication No. 8301159-3 describes a method for the manufacture of raw iron, in which the energy content of the coal is utilized to the maximum. When the coal is used to a maximum it means, in principle, that solely carbon dioxide (CO.sub.2) and steam (H.sub.2 O) leave the process, while charging as little coal as possible to the process. The patent specification discribes herewith a method for producing raw iron from iron concentrates, in which iron concentrate, coal, oxygen gas, and slag-forming flux are injected into a reactor beneath the surface of a molten iron bath present therein, and in which the ratio of CO.sub.2 to CO present in the gas is caused to increase to a value greater than that which corresponds to the state of equilibrium at aatmospheric pressure, thereby causing more heat to be generated in the bath for a given amount of coal, and in which method the amount of coal charged to the system in relation to the amount of concentrate present is predetermined to a sufficiency for finally reducing in the reactor pre-reduced iron concentrate, and in which CO and H.sub. 2 in the waste gases are passed to a pre-reduction stage in which non-reduced iron concentrate is pre-reduced, whereafter, this concentrate is charged to the reactor. Iron concentrates are partially reduced in a pre-reduction stage to a degree considered optimal for final reduction in a reactor.
When applying the iron manufacturing technique disclosed in the Swedish Patent Specification No. 8301159-3 it is necessary to create a balance between the reactor conditions so that raw iron and gas can be produced. The conditions, such as temperature and starting materials, however, are not the optimal conditions, either with respect to the manufacture of iron or to the production of gas, but are the result of a compromise. Thus, serious problems are created with respect to heat balance and the use of reductio
REFERENCES:
patent: 4566904 (1986-01-01), von Bogdandy et al.
patent: 4591381 (1986-05-01), Axelsson et al.
Axelsson Carl L.
Brunner Mikael
Kaufmann Dan
Torsell Krister
IPS Interproject Service AB
Kastler S.
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