Specialized metallurgical processes – compositions for use therei – Processes – Electrothermic processes
Patent
1984-07-19
1985-12-10
Rosenberg, Peter D.
Specialized metallurgical processes, compositions for use therei
Processes
Electrothermic processes
75 515, C21C 700
Patent
active
045577587
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to metallurgy and more in particular to a steelmaking process.
BACKGROUND ART
This invention is applicable to the manufacture of steel from solid iron-bearing charge materials in an oxygen steel-making converter. The iron-bearing charge material may include scrap (metal scrap, rolling crop shear, metal waste from the steelmaking industry, etc.) metallized pellets, sponge iron.
There is known a process of making steel in a converter with the use of a metal charge.
According to this process, the converter is to be equipped with bottom and side tuyeres in the form of a pipe-inside-pipe construction in which the central duct is used for the supply of oxygen and the external one for the delivery of a liquid or gaseous hydrocarbon. The process is carried out as follows.
First, the converter is charged with scrap, sponge iron, solid pig iron and the solid iron-bearing materials. The solid charge is preheated to a temperature of 1000.degree.-1200.degree. C. due to complete burning of a liquid or gaseous hydrocarbonaceous material in an oxidizing gas in accordance with the following reactions: ##STR1##
The following reactions proceed in the oxidizing atmosphere: ##STR2##
The products of combustion are mainly CO.sub.2 and H.sub.2 O, as well as iron oxide.
Once molten metal is formed in the region of tuyeres, powdered hydrocarbonaceous materials (such as coke and coal) are fed into the converter to permit carbonization of the melt formed in the course of heating. As this happens, the consumption of the hydrocarbonaceous material is gradually reduced to a level at which the tuyeres are protected from damage, that is, down to 10-12% of the oxygen consumption. The entire metal charge is melted down toward the end of this period.
Next, the melt is refined in accordance with common practice such as performed during blowing of molten pig iron. The heating of the bath is effected by means of the heat resultant from the last-mentioned reaction, with CO prevailing in the flue gases. At the same time, powdered lime is introduced into the bath together with oxygen to form a slag bath.
On reaching a required temperature, the heat is poured into a ladle in which the metal undergoes deoxidation and alloying, and, if necessary, is subjected to further treatment.
The method described above is disadvantageous in that it requires blowing of powdered hydrocarbonaceous materials into the converter, the preparation and transportation of which necessitate installation of auxiliary equipment (mills, pipes for feeding coal-dust fuel) and, consequently, extra capital costs. Another deficiency of the above method is a substantial waste of iron due to its oxidation at the stage of preheating the scrap charged into the converter. The iron oxides make up the base of the first slag, which subsequently interact with the hydrocarbon of the powdered coke or coal injected into the bath, according to the reaction of direct reduction: increase the time period required for feeding powdered hydrocarbonaceous materials due to lack of heat needed to ensure complete melting-down of the metal scrap. At the same time iron oxide continue to get into the slag since oxidation of iron takes place mainly during oxygen blowing.
The above disadvantages are partly obviated by using lump hydrocarbonaceous fuel (coke or coal). The solid fuel charged with metal scrap ensures, along with the heat released according to the reactions (1)- (4), the heating of the charge due to the heat resultant from the following reaction:
In addition, the presence of solid hydrocarbonaceous fuel in contact with the metal scrap promotes its quicker melting due to decreasing melting temperature of the charge because of its carbonization. Nevertheless, it has been observed that the time period of the stage at which the charge is completely melted in the course of direct reducing reaction (8) is likewise prolonged even though the heats are operated on a solid fuel. This is established by the fact that on consuming from 40-50 to 70-80 m.
REFERENCES:
patent: 4178173 (1979-12-01), Gorges
patent: 4198230 (1980-04-01), Brotzmann
patent: 4334921 (1982-06-01), Hirai
Blinov Konstantin A.
Ivashina Evgeny N.
Jugov Petr I.
Kolganov Gennady S.
Mizin Vladimir G.
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