RU2255982C1 - Method of making steel in oxygen converter - Google Patents

Abstract

FIELD: ferrous metallurgy; melting steel in converter.

SUBSTANCE: proposed method includes loading metal scrap, pouring cast iron and slag-forming component containing lime and ferruginous dolomite whose consumption is found from the following expression: G_{fer ir}=0.053*Si_ir+G_ir+0.22*N^0.4, where G_fer.ir is mass of ferruginous dolomite, t/melting: Si_ir is content of silicon in iron, %; G_ir is mass of iron, t; N is ordinal number of melting in converter campaign; 0.053 and 0.22 are empirical coefficients. Since required content of MgO in slag is maintained in converter campaign due to determination of mass of ferruginous dolomite, smooth wear of working layer of converter lining is obtained.

EFFECT: enhanced resistance of converter lining; increased yield of steel.

1 tbl, 1 ex

Description

The invention relates to ferrous metallurgy, and more particularly to methods of steel smelting in a converter.

A known method of steelmaking in an oxygen converter using ferrous lime-magnesia flux as slag-forming materials. The flux consumption is 10–11 tons for smelting (“Steel No. 11, 2000, pp. 46–48,“ Use of iron-calcined lime-magnesia flux in converter smelting ”, K. N. Demidov and others).

The disadvantage of this method is the constant consumption of ferruginous lime-magnesia flux throughout the company, which at the beginning of the company leads to a decrease in the capacity of the converter due to the greater thickness of the lining, reduces the performance of the unit. At the end of the company leads to low stability of the melt purge process by increasing the capacity of the Converter.

Closest to the claimed is a method of steel production in an oxygen converter comprising loading scrap metal, cast iron casting and a slag-forming component consisting of a mixture of lime and iron dolomite, and purging the bath with a gaseous oxidizing agent when the consumption of iron dolomite is set depending on the silicon content in the cast iron and the mass of cast iron , the required basicity of the slag, the content of CaO in the slag (RF patent for the invention No. 22003329, IPC ⁷ C 21 C 5/28).

Signs of the closest analogue that coincide with the essential features of the claimed invention: loading of scrap metal, cast iron casting, introduction of a slag-forming component, consisting of a mixture of lime and iron dolomite, blowing the bath with a gaseous oxidizing agent.

The known method does not provide the desired technical result.

The introduction of ferruginous dolomite with a constant consumption of slag-forming materials leads to a decrease in the thickness of the lining of the converter at the end of the company, and due to shotcrete, it is possible to achieve the required thickness of the lining, respectively, of the durability of the converter, which leads to a decrease in steel production.

The basis of the invention is the task of improving the method of steelmaking in an oxygen converter, in which by choosing the optimal consumption of ferruginous dolomite, high resistance of the refractory lining of the converter is achieved and steel production is increased.

The problem is solved in that in the method of steelmaking in an oxygen converter, which includes loading scrap metal, casting iron, introducing a slag-forming component, consisting of a mixture of lime and iron dolomite, and blowing the bath with a gaseous oxidizer, when the flow rate of iron dolomite is determined from the expression:

G _O.D. = 0.053 * Si _{cast iron} * G _{cast iron} + 0.22 * N0.4,

where G _O.D. - mass of ferruginous dolomite, t / smelting;

Si _PIG - silicon content in cast iron,%;

G _PUR - mass of cast iron, t;

N - serial number of the heat in the converter campaign;

0.053 and 0.22 are empirical coefficients.

The essence of the proposed technical solution lies in the consumption of ferruginous dolomite, taking into account the serial number of the heat in the converter company.

Upon reaching the resistance of the lining of the converter above 1000 heats, wear of the working layer in individual sections of the cylindrical part and the upper cone is up to 100%. Very high wear of the converter lining in the loading area due to destruction and abrasion by scrap metal and in the area of the steel outlet due to the longer residence of the metal and its erosive effect on the lining during production.

In the course of the company, the carbon component of the refractory burns out, due to which the thickness of the working lining of the converter decreases and its slag resistance decreases, therefore, the consumption of ironed dolomite depending on the serial number of the smelter in the converter company allows maintaining a uniform thickness of the working layer of the converter lining, increasing the converter durability and steel production . This method is illustrated by the following example.

Smelted steel grade 08ps in accordance with GOST 9045-93. The lining resistance of the converter 1138 heats. The consumption of liquid pig iron is 301 tons. The content of silicon is 0.58% silicon, 0.017% sulfur and 0.063% phosphorus. The estimated amount of ferruginous dolomite for melting is 12.9 tons.

Ironized dolomite in the amount of 8.6 tons was transferred to the converter before casting iron together with 4 tons of lime. Then they poured liquid iron and filled up 97 tons of scrap metal.

Purge was conducted through a six-nozzle lance with an oxygen flow rate of 1150 m ³ / min. During the purge, two servings of lime were added: 2.1 and 2 tons at 4 and 11 minutes and two servings of fermented dolomite 2.2 and 2 tons at 7 and 9 minutes. The purge duration was 18 minutes, the oxygen consumption was 20848 m ³ .

After the purge was completed, the temperature of the metal was measured, which amounted to 1665 ° C, and samples of metal and slag were taken. The chemical composition of the metal was determined by the spectral method, and slag was determined by the X-ray spectral method. The metal contained: carbon 0.04%, manganese 0.049%, sulfur 0.017%, phosphorus 0.005%, slag 37.4% CaO, 10.3% SiO ₂ , 27.8% FeO, 12.8% MgO, 3, 3% MnO, 0.06% S and 0.7% P ₂ O ₅ .

After that, the metal was released into the steel pouring ladle. In the course of metal production, 896 kg of ferromanganese FMN 88, 600 kg of aluminum, 458 kg of fluorspar and 2 tons of lime were added to it.

Further processing of the smelting was carried out on a steel finishing unit. To adjust the chemical composition, 176 kg of ferromanganese FMN 70 and 367 kg of aluminum wire rod were added to the metal.

Casting was carried out on slab caster. Finished steel contained 0.044% carbon, 0.02% silicon, 0.24% manganese, 0.008% phosphorus, 0.012% sulfur.

Some examples of heats are given in the table.

Providing the required MgO content in the slag, depending on the smelting serial number in the converter company, by calculating the weight of the ironed dolomite, it is possible to achieve uniform wear of the working layer of the converter lining and increase production.

Claims (1)

A method of producing steel in an oxygen converter, including loading scrap metal, casting iron, introducing a slag-forming component consisting of a mixture of lime and iron dolomite, and blowing the bath with a gaseous oxidizing agent, characterized in that the consumption of iron dolomite is determined from the expression G _O.D. = 0.053 Si Si _CH · G _CHG + 0.22 · N ^0.4 , where G _O.D. - mass of ferruginous dolomite, t / smelting; Si _PIG - silicon content in cast iron,%; G _PUR - mass of cast iron, t; N is the sequence number of the heat in the converter campaign; 0.053 and 0.22 are empirical coefficients.