Process and device for direct production of steel from iron-containing materials

Inactive Publication Date: 2006-01-19
BOUROVOI ISSAAK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0050] Oxygen-containing gas flows supplied to the upper zone provide for bubbling of the melt with the aim of intensifying the process of heat- and mass-transfer during melting and reduction.
[0056] The application covers two structures of R-subspace organization with one-stage and two-stage refining and two regimes for both structures: first, when oxygen enters with Fe oxides and in the form of directed jets at the level of intermediate layer lower boundary (variant with upper blast) and the second, when bottom supply of oxygen and / or CO2 and / or air, and / or inert gases, and / or their different mixtures (variant with combined blast). Combined blast permits to realize technological regimes with higher specific productivity and lower fuel consumption. During one-stage refining, the steel obtained is mainly discharged from the lower zone and in case of necessity goes to out-of-furnace processing and refining according to the given regulations before casting.
[0061] As the result of the decarburization reaction carbon oxide isolation takes place which increases agitation in emulsion layer; coefficient of turbulent-diffusion transfer and interphase surface in emulsion layer are growing, thus leading to increase in the speed of occurring chemical reactions and increase in oxygen delivery. Speed of decarburization processes increases and metal “boils”. Metal refining from admixtures is also intensified.

Problems solved by technology

As for the second stage, converting is a periodic process requiring separate equipment, thus characterizing the first essential drawback of this stage.
The other drawback of the converting process consists in the fact that the oxygen flow delivered into the melt, reacts with carbon and simultaneously partially oxidizes iron turning it into slag.
Implementation of the modern technology for steel production as two subsequent operations (stages) in two independent metallurgical plants possesses one more rather important drawback—an economical one: steel production cost is sharply increased due to application of two independent devices.
Such mating of Romelt furnace with refining installations somehow shortens the time of additional metal heating, but doesn't exclude the necessity of this operation: refining is carried out in semi-continuous regime, necessitates separate maintenance and, hence, additional expenditures.
However, with the reaction chambers layout applied it seems doubtful to obtain effective mass- and heat-transfer between reacting masses “slag-metal” in larger and smaller reaction chambers and to get sufficiently high carbon oxidation in metal produced.
It is known that Romelt furnace productivity is limited due to rectangular cross-section accepted.
Romelt technology as well as Hismelt, Dios and others known in the world, doesn't permit to decrease carbon content in metal obtained lower than ˜3.5.-4.0% and produce steel.

Method used

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  • Process and device for direct production of steel from iron-containing materials
  • Process and device for direct production of steel from iron-containing materials
  • Process and device for direct production of steel from iron-containing materials

Examples

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Effect test

example 1

[0278] When refining carbon iron product obtained in the upper zone, it is very important to carry out intensive agitation of the melt in the lower zone. Gas flows entering the refining subspace from intermediate emulsion layer and bottom blast provide for melt agitation by bubbling. However, upper and bottom blasts possess several balance limitations.

[0279] The present application studies agitation of metal in the lower refining zone by means of short pulse interruptions in solid carbonic fuel supplied to the furnace as one of the operational methods of attaining the goal.

[0280]FIG. 7a shows diagrams of state variables and flows of charge processed, oxygen-air blast and pulse interrupted solid carbonic fuel supplied to the furnace. Interruption is carried out with one hour interval, pulse amplitude equals to ˜0.9 from supplied flow Fpy, and length of pulse is only ˜0.05 h.

[0281] As diagrams show, such short interruptions in the fuel supply are sufficient for exciting considerabl...

example 2

[0284] Approach to applying the proposed method to direct steel production has been studied above in detail, the main attention having been paid to the technology of attaining direct steel production.

[0285] The present example studies the technology of temporary, rather long furnace shut-down and its further start-up for the previous regime of direct steel production. In this case we discuss not the complete shut-down for capital repairs, but shut down for the period of 6 hours for conducting current repairs.

[0286]FIG. 8a presents changes in state variables and flows of charge, oxygen-air gas and fuel supplied to the furnace in the process of carbon iron product production (from 0 to 1 hour), starting steel production (from 1 to 5 hours), steel production (from 5 to 6 hours), 6 hour shut-down with termination of loading the charge processed and decrease for 50% in fuel supply and oxygen-containing gas (from 6 to 12 hours); then, subsequent furnace start-up for stationary regime of...

example 3

[0293] This example studies the problem of effective organization at the start-up process when the furnace carries out transition from carbon iron product production for steel production. Attentive studying of the start of the process in FIG. 2b for both examples given above, shows that the start of the transition process in refining zone lags behind from the moment of first pulse application: with two pulse start-up for 0.45 h, with three pulse start-up for 0.6 h, in some cases the time lag was more than 1 h (FIG. 9a). Time lag described prolongs starting time and, what is more important, highly complicates operative control for start-up operations and process control under conditions of normal exploitation.

[0294] Due to that, the application for the patent provides for the variant of additional oxygen supply for the time of all the furnace operation during furnace transition for steel production by means of bottom blow-down in case it has not been installed beforehand.

[0295]FIG....

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Abstract

Process and device for direct continuous steel production out of iron-containing materials using usual power coals as fuel and reducer. It is provided to carry out the process in a single reaction space comprising a layer of liquid refining metal present under a layer of liquid slag comprising iron-containing materials to be processed and droplets of reduces metal so that an intermediate emulsion layer “slag-gas-metal” is designated in between the said layers. In an upper slag layer fuel is burnt and finely grained iron-containing materials are reduced according to coke-free technology of cast-iron production with carbon content at the level of ˜4.5-4.8%; iron oxides and reduced metal droplets are transferred from slag layer into intermediate emulsion layer; iron oxides are decomposed and oxygen is isolated together with oxygen-containing gas supplied to emulsion layer. Refining process proliferates to lower refining layer and carbon oxide isolated during refining stimulates reduction processes in slag layer. Basic structure of the device with single reaction space can be adapted to different technological problems and peculiarities of properties in iron-containing materials processed. The solution proposed permits to obtain steel with carbon content within the limits of 0.2-2.0% and with permissible content of admixtures having specific productivity of the device up to 2.0-2.5 t / m2 of bottom per hour and productivity of a single unit equal to 50,000-5000 000 t / year.

Description

FIELD OF INVENTION [0001] The present invention related to the field of metallurgy, to ferrous metallurgy in particular, and is destined for direct continuous steel production from non-agglomerated iron ore, iron ore concentrates, iron containing waste and other iron-containing materials. BACKGROUND OF THE INVENTION [0002] Steel production is usually based on two main production stages: [0003] (1) iron reduction from iron containing materials and production of iron-carbon product—cast iron with relatively high carbon content. [0004] (2) refining of the iron-carbon product—cast iron obtained with the aim of decreasing carbon content and admixtures up to the determined limits and producing steel. [0005] Previously, the first stage was usually performed by melting in the blast furnace where high quality metallurgical coke is used for iron reduction from oxides. The invention proposed relates to performing this process in the bubbled slag melt using elements of modern coke-free reductio...

Claims

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Application Information

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IPC IPC(8): C21B5/00
CPCC21B13/0013C21C2300/02C21C5/567Y02P10/134
InventorBOUROVOI, ISSAAK
OwnerBOUROVOI ISSAAK