Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-07-22
1999-12-07
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75450, 75492, 75505, 266156, 266160, 266172, C21B 1100
Patent
active
05997608&
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the production of molten pig iron or molten steel pre-products and sponge iron from charging materials consisting of iron ore, preferably lumpy and/or pelletized iron ore, and, if desired, fluxes, wherein direct reduction of the charging materials to sponge iron is carried out in a first reduction zone, the sponge iron is melted in a meltdown gasifying zone under supply of carbon carriers as well as an oxygen-containing gas and a CO- and H.sub.2 -containing reducing gas is produced which is fed to the first reduction zone, is reacted there and is drawn off as an export gas, and wherein the drawn-off export gas is subjected to CO.sub.2 elimination and for the production of sponge iron is along with part of the reducing gas formed in the meltdown gasifying zone as an at least largely CO.sub.2 free reducing gas conveyed exclusively to a further reduction zone for the direct reduction of iron ore, and a plant for carrying out the process.
A process of this type is known from AT-B - 396.255. There, the portion of the reducing gas produced in the meltdown gasifying zone that forms as an excess gas and is supplied to the additional reduction zone is washed in a scrubber, is subsequently mixed with the export gas and is finally subjected to CO.sub.2 stripping along with the export gas. Thus, this portion of the reducing gas is added to the export gas before the CO.sub.2 stripping is effected, so that the two reduction processes--each of them individually embodying a system that is subject to oscillations--are connected with each other at a point which--if viewed from the gas stream--is situated closely after the first reduction process and far away from the second process. Thereby it becomes feasible to minimize or avoid possible effects of oscillation transfers between the systems, resonances and feedback with regard to gas throughputs, gas compositions and gas temperatures, namely by homogenizing or cushioning the various deviations from the designated desired values. For example, fluctuations in gas volume and flow arise from the demand to maintain a constant system pressure of the melter gasifier for the purpose of producing a reducing gas of a steady quality. As soon as the pressure in the melter gasifier becomes too high, a relaxation is effected by increasing the supply of reducing gas to the export gas duct.
The dimensions of a CO.sub.2 stripping means are, alongside other criteria, largely a function of the flow volume which is to be supplied to the plant, and in this connection, in accordance with AT-B - 396.255, the maximum reduction gas flow to be expected has to be taken into account. Since the CO.sub.2 stripping means accounts for an essential part of the overall investment incurring in connection with a plant for carrying out a process of the initially described kind, the investment costs for a plant according to AT-B - 396.255 are very high.
The invention has as its object to develop further the process known from AT-B - 396.255 as well as the plant known from the said document in such a way as to enable substantial savings in terms of investment costs. In particular, it is to be feasible to decrease the amount of energy required for producing the product.
With a process of the initially defined kind, this object of the invention is achieved in that from the part of the reducing gas produced in the meltdown gasifying zone and conveyed exclusively to the further reduction zone a portion is branched off and fed to the further reduction zone hile avoiding CO.sub.2 elimination and that the export gas subjected to CO.sub.2 elimination is heated.
Consequently it is feasible according to the invention to dimension a plant for CO.sub.2 elimination for a substantially lower capacity, whereby investment costs are lowered substantially. Surprisingly, it emerged that moving the linkage point of the two reduction processes closer to the further reduction zone entails no negative effects on the overall process. In the event that substantial fluctuations in terms of gas volu
REFERENCES:
patent: 5238487 (1993-08-01), Hauk et al.
patent: 5676732 (1997-10-01), Viramontes-Brown et al.
Diehl Jorg
Kepplinger Leopold Werner
Milionis Konstantin
Rosenfellner Gerald
Siuka Dieter
Andrews Melvyn
Voest-Alpine Industriean-lagenbau GmbH
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