RU1786094C - Steelmaking process - Google Patents

Abstract

Usage: in the field of metallurgy and, in particular, in methods for producing steel in oxygen converters. The goal is to increase the yield and decrease the consumption of ferroalloys. SUMMARY OF THE INVENTION: a part of the steel melt from the previous melting is left in the converter, cast iron is poured, oxygen is blown into it, scrap metal is introduced and melted by heat of steel overheating, the amount of steel left is determined from the Ois / C ratio (twaicc-ti ™), where MF - the amount of cast iron in the heat, kg, Oiz - specific excess bath heat, kcal / kg of cast iron, C - heat capacity of the melt, kcal / kg deg .; Tmax -1 maximum permissible melt temperature after purging, ° C; 1 mp melt outlet temperature, ° C.

Description

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The invention relates to the field of metallurgy, in particular to methods for producing steel by the oxygen-converter method.

A technical solution is known, according to which cast iron is poured into the converter, scrap is piled up, slag-forming agents are introduced, oxygen is blown, steel is released and slag is downloaded.

The disadvantages of this method are the significant oxidation of scrap during oxygen blowing, the greater consumption of ferroalloys for slag deoxidation, and the short service life of refractories.

A technical solution is also known, characterized in that part of the melt of the previous melting is left in the bathtub, the scrap is filled up, cast iron is poured, oxygen blowing, slag guidance, melt discharge and downloading are carried out

slag. Its disadvantage is a decrease in converter performance.

The aim of the invention is to increase the yield and durability of the lining, while reducing the consumption of ferroalloys.

This goal is achieved in that according to the method of steel production, which includes leaving the previous melt part of the melt in the bath, filling the scrap metal, casting iron, blowing with oxygen, slag inducing, releasing the melt and downloading slag, dump the scrap into the bath and melt after the melt has been purged with oxygen at a temperature exceeding the temperature of the outlet of the heat and the amount of melt left of the previous heat is determined by the expression

iVj 00

CN

ABOUT

Yu

N

Cst

Q,

C (Tmax - tn / i)

(1)

where GCT is the amount of melt left, kg;

G4 - the amount of cast iron in the heat, kg;

Oiz - specific excess heat of the bath, kcal / kg of cast iron;

C is the heat capacity of the melt, kcal / kg-deg;

tMaKc — maximum permissible melt temperature after purging, ° С;

t, pl - the temperature of the release of the heat

The method is carried out as follows:

In an oxygen converter, the metal melt GCT is left from the previous melt. The calculated mass of cast iron MF is poured into it in accordance with equation (1), slag-forming substances are introduced and purged with oxygen, while mixing the melt: with an inert gas using gas blowing. As a result, impurities are oxidized and the temperature of the system rises to Gmax. After that, the calculated portion of scrap metal preheated outside the furnace is loaded into the converter. The excess heat of the Oiz bath melts the scrap metal, and the resulting melt temperature decreases to Tm. At this temperature, the steel is discharged into the ladle, left in the GCT converter, and the process is repeated.

An example implementation of the method.

In a converter designed for a cage of 400 tons, 257 tons of steel with a temperature of 1610 ° C are left from the previous smelting. Then, 44 tons of cast iron, determined by the formula (1), are introduced into it, with the following initial data: gMax 1700 ° C; t ™ 1610 ° C; 879 kcal / kg deg; kcal / kg of cast iron.

The melt is purged with oxygen at a flow rate of 900-1500 m / min, and as a result of the oxidation of impurities, the mass of steel is set at 299 tons, and the temperature of the system rises to 1700 ° C. Then 83.3 tons of scrap, heated outside the furnace to 1350 ° C, are dumped into the converter. Within 3 minutes, the scrap metal is melted and the temperature of the melt decreases to 1610 ° C. At this temperature, 125 tons of steel are poured into the ladle through the bottom outlet, then 12 tons of slag are downloaded from the converter. After the described operations, the converter is ready for further melting, and the previously listed processes are repeated.

The advantages of the invention are due to the following;

1. The yield is increased by 0.5-0.8%, since scrap metal is not melted by oxygen, but by the heat of overheating of the bath.

, 2. Due to the lower oxidation of the slag, the consumption of ferroalloys will decrease by 1.5 kg / t of steel.

3. Melting in the proposed mode narrows the range of temperature fluctuations of the lining from 500-600 to 230 ° C, respectively, the consumption of refractories is reduced.

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Claims (1)

The claims Method of steel production, including leaving the previous melt part of the melt in the bathtub, scrap metal filling, cast iron pouring, oxygen blowing, slag induction, melt discharge, slag charging, characterized in that, in order to increase the yield and durability of the lining, reduce the consumption of ferroalloys, scrap metal heaped into the bath and after the melt is purged with oxygen, the melt is melted at a temperature exceeding the temperature of the melt outlet, and the amount of the remaining melt of the previous melt is determined as follows expression: SST-Oiz MF / S max pl), where GCT is the amount of melt left, kg; MF the amount of cast iron in the heat, kg; Oiz-specific excess heat bath, kcal / kg of cast iron; . C is the heat capacity of the melt, kcal / kg deg; tMaKc — maximum permissible melt temperature after purging, ° С; 1pl melt discharge temperature, ° С.