RU2347819C2 - Method of steel production in oxygen converter - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to iron and steel industry, particularly to methods of steel production in oxygen converters. The method consists in charging metal scrap and iron containing product of final slag processing containing metal and slag ingredients, in charging lime, in pouring iron, and in blasting pool with gaseous oxidiser. In the process of charging magnesia flux is additionally introduced at ratio of weight of magnesia flux, lime and iron containing product of final slag processing equal to 1:(8-11):(5-35) correspondingly; also the latter is charged at amount of 10-50% from the weight of solid metal charge.

EFFECT: improvement of process of slag forming, increase of resistance of lining and reduced consumption of slag forming materials and metal charge.

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Description

The invention relates to ferrous metallurgy, in particular to methods for the production of steel in converters using various types of scrap in a metal mill.

There is a known method of producing steel in a converter, including feeding the slag of the previous melting and scrap metal into the converter, casting iron, introducing slag-forming materials, purging with oxygen, and before feeding the slag into the converter, they are pre-frozen on the surface of the scrap metal (SU No. 1832725, C21C 5/28, publ. 1989 )

The disadvantages of this method include the low productivity of the technology of freezing slag on scrap, the need to use a mixer to store liquid slag, the inability to accurately dispense scrap and slag, which leads to the formation of a large amount of slag, slag and metal emissions from the converter during purging, to prevent which intermediate loading of slag is required, while the loss of metal with slag and the consumption of metal charge increase.

Closest to the claimed technical essence is a method of steel production in an oxygen converter, including loading scrap metal, lime, cast iron casting, blowing a bath with a gaseous oxidizing agent, and additionally loading an iron-containing product for processing waste slag consisting of metal - 60% and slag - 40% components, and the slag component contains oxides of calcium, silicon, magnesium, aluminum, manganese and iron, while the consumption of lime is determined depending on the content of belt in cast iron, its consumption, the necessary basicity of slag and the consumption of iron-containing product for processing waste slag (RU No. 2169197, C21C 5/28, publ. 1999).

The disadvantage of this method is that it does not provide highly magnesian converter slag, since only the iron-containing waste slag processing product containing up to 6% MgO in the slag component is used, and the harmful effect of slag on the converter lining is not achieved. To increase the MgO content in the slag, it is necessary to load a large amount of iron-containing product for the processing of waste slag due to the insufficient MgO content in its slag component, which leads to the formation of an increased volume of slag in the converter, metal and slag emissions during the purge purge, the need to stop the purge, intermediate download slag, blowing and guidance of new slag, while increasing the loss of metal with slag, the consumption of metal charge and slag-forming materials.

The objective of the invention is to improve the process of slag formation, increase the durability of the lining, reduce the consumption of slag-forming and metal charge.

To solve this problem, in a method involving loading a solid metal charge, including scrap metal and an iron-containing product for processing waste slag, consisting of metal and slag components, loading lime, pouring cast iron, blowing the bath with a gaseous oxidizing agent, according to the invention, magnesia flux is additionally introduced during loading, when the mass ratio of magnesia flux, lime and iron-containing product for the processing of waste slag is 1: (8-11) :( 5-35), respectively, with the latter s is charged in an amount of 10-50% by weight of the solid metal charge.

The technical result that can be obtained using the proposed method is to obtain a high content of magnesium oxides in the converter slag at its optimum amount, which prevents the emission of metal and slag during purging, reduces metal loss, consumption of metal charge and slag-forming materials.

The technical result is achieved with the specified set of features in the claims.

An additional loading of magnesia flux increases the content of magnesium oxides in the slag to the required level of at least 10%, at which the slag is non-aggressive and its harmful effect on the refractory lining of the converter is reduced.

Additives of magnesium-containing material, lime and iron-containing product for processing waste slag with a quantitative ratio of 1: (8-11) :( 5-35), taking into account the content of MgO and CaO in the slag component of the iron-containing product, provide the formation of an optimal amount of highly basic slag, reducing metal emissions and slag during purging and reducing metal loss with low consumption of slag-forming materials.

With a ratio of less than 1: 8: 5, for the guidance of highly basic slag with an MgO content of ≥10%, the consumption of lime and magnesium-containing material increases, which leads to an increase in costs in the production of steel.

When the ratio is more than 1:11:35, a large amount of slag is formed, which is accompanied by emissions of metal and slag during the purge, the loss of metal with slag and the consumption of metal charge increase.

The loading of the iron-containing product for processing slag waste in an amount of 10-50% by weight of the solid metal charge allows us to improve the process of slag formation by using calcium and magnesium oxides contained in the slag component of the iron-containing product, reduce the consumption of materials for melting, and optimize the amount of slag generated in the converter.

Download iron product of processing waste slag in an amount of more than 50% by weight of the solid metal charge leads to the formation of a larger amount of slag, which contributes to an increase in metal and slag emissions during purging and an increase in the consumption of metal charge.

When loading an iron-containing product in an amount of less than 10% by weight of a solid metal charge, the consumption of lime and magnesium-containing material increases.

Using the method of steel production in an oxygen converter is as follows.

Example (option 3, table). When 3ps grade steel was smelted in 160 tons of the converter of the oxygen converter shop No. 1 of ZSMK OJSC, 44 tons of solid metal charge were loaded into the converter, including 31 tons of scrap metal and 13 tons (30% of 44 tons) of the iron-containing waste slag processing product fractions up to 500 mm containing 25% slag component with a content of 42% CaO and 14% MgO. Then, lime in an amount of 7.2 tons and magnesia flux with a content of 70% MgO in an amount of 0.8 tons were loaded and 107.2 tons of cast iron with a content of 0.40% Si were poured; 0.42% Mn; 0.025% S, 0.0096% P. The bath was purged with gaseous oxygen using conventional technology. The purge took place without emissions of metal and slag. During the conversion of the converter, the metal temperature was 1630 ° С, the chemical composition of the metal: С - 0.06%, Mn - 0.10%, S - 0.019%, Р - 0.020%; slag: CaO - 49%, MgO - 12%, SiO ₂ - 15%, MnO - 3%, FeO - 19%, basicity - 3.3. The consumption of lime was 51.4 kg / t, magnesia flux 5.7 kg / t, metal charge 1108 kg / t. The mass ratio of magnesia flux, lime and iron-containing product for processing waste slag was 1: 9: 16.

The results obtained using the proposed method for the production of steel in an oxygen converter are shown in the table.

Table Option Magnesia flux consumption, kg / t steel Lime consumption, kg / t steel The amount of iron-containing product The ratio of the masses of flux, lime and iron-containing product Metal charge consumption, kg / t steel The MgO content in the slag,% % of solid metal charge kg / t steel one 7.1 55.0 10 32.1 1: 8: 5 1110 10 2 6.4 52.8 twenty 64.3 1: 8: 10 1109 eleven 3 5.7 51,4 thirty 92.9 1: 9: 16 1108 12 four 5,0 49.3, 40 121,4 1:10:24 1110 13 5 4.3 47.5 fifty 150.0 1:11:35 1111 fourteen

The results shown in the table show that the use of the proposed method for the production of steel in an oxygen converter, with the claimed limits of quantitative characteristics, allows to obtain a low consumption of lime 47.5-55.0 kg / t, magnesia flux 4.3-7.1 kg / t, metal charges 1108-1111 kg / t and provide a high MgO content in the converter slag at the level of 10-14%.

The proposed method is industrially applicable and can be used in steelmaking in the smelting of steel in an oxygen converter.

Claims (1)

Method for the production of steel in an oxygen converter, including loading a solid metal charge, in the form of scrap metal and an iron-containing product for processing waste slag, consisting of metal and slag components, loading lime, casting iron, blowing the bath with a gaseous oxidizing agent, characterized in that the lime is additionally introduced during the loading process magnesia flux when the mass ratio of magnesia flux, lime and iron-containing product of waste slag processing is 1: (8-11) :( 5-35), respectively, at this last load in the amount of 10-50% by weight of solid metal charge.