RU1836438C - Procedure of iron-carbon melt converting - Google Patents

Abstract

Usage: in ferrous metallurgy, in particular, with methods for processing iron-carbon melts (cast irons) with a low concentration of silicon and manganese in an oxygen converter. Summary of the invention: lot and lime are salted into the converter, an intermediate product of the liquid-phase reduction (ППЖВ) is poured as an iron-carbon melt and slag a liquid phase reduction process (SHLV) in an amount of 0.5-2.0% by weight of a metal charge. ШПЖВ is used as a slag-forming material and can be poured together with ППЖВ. 1 s.p. f-ly, 4 ave.

Description

FIELD OF THE INVENTION The invention relates to ferrous metallurgy, in particular, to a method for processing iron-carbon melts (cast irons) with a low concentration of silicon and manganese in an oxygen converter. , The aim of the proposed method is to improve the conditions of slag formation, reduce metal loss with spray mist and brown smoke and reduce heat costs for the process of slag formation.

This object is achieved in that in a method for converting an iron-carbon melt, including filling the scrap, lime pouring the iron-carbon melt and the additive of slag-forming materials, purging with oxygen according to the invention, the slag of the process is filled together with the latter after filling the scrap and pouring the melt, or together with the latter (ПЖВ) in an amount of 0.5 - СО 2.0% of the weight of the metal charge. and as the CO of the iron-carbon melt, the semi-product of the liquid-phase recovery process is | S laziness. л d}

Pouring liquid slag of the ПЖВ into the QQ converter improves the conditions of slag formation by increasing the dissolution rate of the adhering lime lime, especially in the initial SLW purge period, reduces metal loss with spray mist and brown smoke, introduces additional heat from the slurry. slag formation, in turn, leads to an increase in converter performance and creates more favorable kinetic conditions for the removal of phosphorus and sulfur from the metal.

The proposed method for converting an iron-carbon melt can be implemented as follows. The chemical composition of the intermediate ПЖВ,%: carbon - 4.0, silicon g 0.1. manganese - 0.1, phosphorus - b; f, sulfur - 0.06; ПЖВ slag,%: CaO - 35.0; SlOiz - 40.0, MfnO - 2.0, FeO - 3.5, Fe203 - 1.65, MgO - 7.5, P.0s - 0.25, A1gO3 - 10.0 S - 0.10. Steel before deoxidation contains,%: carbon - 0.06, manganese - 0.05, phosphorus - 0.015, sulfur - 0.030.

Kuskova lime is supplied in three doses: 1/3 before the start of the purge and the rest during the purge of the iv.

Example 1. A converter with a capacity of 350 tons is used for filling 55 tons of steel scrap, pouring 315 tons of semi-finished products ПЖВ and 7 tons, (2%) of slag, ПЖВ, followed by purging the melt with oxygen. The amount of lime to be added, up to a basic value of sh / such 3.0, is 9.45 tons (27 kg / ton of steel).

Compared with the option of converting iron-carbon melt without the use of slag ПЖВ, the method of converting using 2% slag ПЖВ leads to an increase in the total amount of the final converter slag from 36 kg / t of steel to 60 kg / t of steel, the total content of iron oxides in the slag (in terms of ferrous oxide) is reduced from 29.5 to 17.7%.

An increase in the amount of final slag does not lead to an increase in iron loss c. final slag, and the heat loss associated with an increase in the total amount of slag is compensated by the introduction of heat with slag ПЖВ, Due to the presence of liquid slag ПЖВ, able to actively assimilate lime, the amount of undigested lime in the final slag decreased from 10 to 2.1%, metal loss with spray mud and brown smoke decreased from 1.7 to 1.0%, and the duration of the purge period decreased from 17 minutes to 16.4 minutes.

Example 2. A converter with a capacity of 350 tons is used for filling 55 tons of steel scrap, pouring 315 tons of semi-finished product ПЖВ and 9.25 tons (2.5%) of ПЖВ slag, and the melt is purged with oxygen. The number of people to sit is 10t.

In this embodiment, all considered process indicators remain at the level of indicators in example 1: the amount of undigested lime was 2.0%, the loss of metal with spray nozzle and brown smoke

0

5

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5

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1.0%, purge duration 16.4 min. However, an increase in the total amount of final slag from 36 to 71 kg / t of steel with a total iron oxide content of 17.7% leads to an increase in iron and final slag losses compared to Option 1 by 1.5% (15 kg / t of steel) . The specific consumption of lime also increases from 27 to 29 kg / t of steel.

Example 3. A converter with a capacity of 350 tons is used for filling 55 tons of steel scrap, pouring 315 tons of semi-finished product ПЖВ and 1.8 tons (0.5%) of ПЖВ slag, followed by purging the melt with oxygen. The total amount of lime sown is 7 tons (20 kg / g of steel). The amount of the final converter slag according to this option increases from 36 to 38 kg / t of steel, which, with a decrease in the concentration of iron oxides and slag from 28.9 to 20.5%, leads to a decrease in iron loss with downloadable slag by 0.2% (2.0 kg / t of steel). Loss of metal with spray mist and brown smoke is also reduced by 0.2% (2 kg / t of steel). The amount of undigested lime in the slag was 8%. The total purge time was 16.75 minutes.

Example 4. A converter with a capacity of 350 tons is used for filling 55 tons of steel scrap, pouring 315 tons of the intermediate ПЖВ and 1.1 tons (0.3%) of the slag ПЖВ, followed by purging the melt with oxygen. The amount of lime adhered is 6.5 tons (18.6 kg / t of steel). With a total increase in the amount of final converter slag from 36 to 37.2 kg / t of steel and a decrease in the total content of iron oxides in the slag from 29.5 to 22.3%, the loss of metal with slag decreases by 0.16% and the amount of undigested lime in the slag was 9 ,5%. Loss of metal with spray mist and brown smoke remains at 1.7%, i.e. the same as in the melting option without the use of slag ПЖВ. The purge duration also remained at 17 minutes.

Thus, we can conclude that a decrease in the amount of PZHV slag poured into the converter less than 0.5% becomes ineffective, and an increase in the portion of the PZHV slag over 2.0% leads to a significant increase in the amount of final slag and the associated increased iron and heat losses, and also an increase in the specific consumption of lime.

Using the proposed method for converting iron-carbon melt provides:

improvement (acceleration) of the slag formation process and related increase in converter productivity

an increase in the yield of liquid metal by reducing the loss of metal with spray mist and brown smoke.

Claims (2)

SUMMARY OF THE INVENTION 1. A method for converting an iron-carbon melt, including loading scrap and lime into a converter, pouring an iron-carbon melt, an additive for slag-forming materials, an oxygen purge, characterized in that, in order to improve slagging conditions, reduce metal losses with spray mist and brown smoke, slag-forming material using slag of the liquid-phase reduction process in an amount of 0.5-2.0% by weight of frozen melt. 2. The method of pop, 1, characterized in that the slag is a liquid phase process. reductions are used in the molten state and poured simultaneously with the iron-carbon melt.