Process and device for heating and melting lumps of sponge iron

Details Process and device for heating and melting lumps of sponge iron Process and device for heating and melting lumps of sponge iron

1994-03-18

1995-09-19

Andrews, Melvyn

Specialized metallurgical processes, compositions for use therei

Processes

Process control responsive to sensed condition

75381, 75384, 75385, 75523, 266 78, 266 81, 266 87, 266144, 266217, C21B 1100

Patent

active

054512468

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF INVENTION

The invention relates to a process and an apparatus for heating and melting lumps of sponge ion.
In a known process of the specified kind, metallic iron carriers are heated in a charging material preheater arranged above a melting furnace, and then fed to the furnace. In that case, an economical mode of operation is only possible if the iron carriers used are materials which do not involve excessive reactivity in relation to oxygen, as it is only then that the energy content of the waste gases from the melting furnace can be economically used for the preheating effect, by virtue of post-combustion of the waste gases. If directly reduced material in lump form, that is to say sponge iron in lump form, is to be preheated, then its high level of reactivity, in particular at temperatures above 500.degree. C., requires a reducing atmosphere in order to prevent major oxidation losses when the sponge iron is heated. For that purpose, the sponge iron has been heated, mixed with coke, in a preheater. However such a process necessitates a considerable surplus of energy-rich waste gases and presupposes gas consumers in the vicinity of the installation.
The invention is based on the problem of permitting preheating of the highly reactive sponge iron to temperatures of about 850.degree. C. without substantial oxidation losses, and at the same time avoiding a surplus of energy-rich waste gases. The invention also seeks to provide an apparatus for carrying out that process.


SUMMARY OF THE INVENTION

The process according to the invention is characterised by the features of claim 1. Advantageous configurations of the process are set forth in claims 2 to 9. The apparatus according to the invention is characterised by the features of claim 10. Advantageous embodiments of that apparatus are described in the remaining claims.
In the case of the process according to the invention, the different level of reactivity of sponge iron at temperatures of different levels is utilised by virtue of the fact that the operation of preheating the sponge iron is carried out in a plurality of stages and a given temperature and a given gas atmosphere is associated with each of the preheating stages. While the sponge iron can only be heated with reducing gases at high temperatures of 800.degree. to 900.degree. C., it is possible to heat the sponge iron in a neutral atmosphere in preheating stages at a lower temperature such as 250.degree. C. or 500.degree. C. A substantial increase in the level of economy of the process can be achieved by suitable individual control of the temperature and the gas atmosphere in the individual preheating stages. By means of the apparatus according to the invention, subdivision into different preheating stages and control of the temperature and the gas atmosphere in those preheating stages can be achieved in a fashion which is particularly simple from the structural point of view.


BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a diagrammatic view of the individual steps in the process of an embodiment of the invention.


DETAILED DESCRIPTION

FIG. 1 diagrammatically shows a process for melting sponge iron 10, with four preheating chambers 11 to 14 which are arranged one above the other and which are lined with refractory material, a transportably designed cupola furnace 15 arranged beneath the fourth preheating chamber 14, a coke store 16 with a feed conduit 17 to the cupola furnace 15, a recuperator 18, a gas cleaning installation 19 and a coal store 20.
The first preheating chamber 11 is of a rectangular configuration and has a gas outlet 21 which is connected by way of a conduit 22 to the gas cleaning installation 19, and a charging opening 23 through which sponge iron 10 and limestone 24 can be introduced into the first preheating chamber 11. The floor of the first preheating chamber 11 is mounted slidably and is in the form of a slider 25 for opening and closing of the preheating chamber 11 in order to pass predetermined amounts of sponge iron 10 and limestone 24 directly into the

REFERENCES:
patent: 3702242 (1972-11-01), Fernandes

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