SU1544813A1 - Method of melting low- and medium-carbon steel in double-bath steel-melting unit - Google Patents

Abstract

The invention relates to ferrous metallurgy, and more specifically to methods for smelting steel in double-bath furnaces. The aim of the invention is to reduce the consumption of ferroalloys and increase the yield of metal. The method of smelting low- and medium-carbon steel in a two-bath steel-making unit, including charging and heating the charge followed by pouring iron in one bath and simultaneously blowing oxygen in the other bath. Heating of the melt with an oxygen-oxygen torch begins when the carbon content in the melt reaches 1.3-1.5% with a simultaneous decrease in the initial intensity of oxygen blowing by 1.5-2 times. In steelmaking using this method, the heat of chemical reactions and the fuel-oxygen torch is sufficient to provide the required metal temperature at a given carbon content. There is no need to heat the melt due to the oxidation of iron at the finishing stage, which leads to a reduction in the consumption of ferroalloys and an increase in the yield of the good. 1 tab.

Description

The invention relates to ferrous metallurgy and can be used in the smelting of steel in two-bath furnaces.

The purpose of the invention is to reduce the consumption of ferroalloys and increase the yield of suitable metal.

Heating the melt with the introduction of a fuel-oxygen torch with a carbon content of 1.3–1.5% with a simultaneous decrease in the initial intensity of the oxygen purge by 1.5–2.0 times ensures high heating rates of the melt, corresponding to the oxidation rates of carbon. carbon oxidation and fuel torch reactions are sufficient to provide the required melt temperature for a given carbon content in the finished metal, and there is no need to heat the melt by oxidizing iron and purging bath in the final stages of finishing, as imesl

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In the well-known methods of melting, steel DTO leads to a decrease in the gara of iron and the oxidation of the metal, which increases the yield of the suitable material and reduces the cost of ferroalloys to deactivate the metal.

The optimality of the indicated limits of carbon content in the melt (1.3-1.5%), at which the heating of the Q melt is started with the introduction of a total oxygen torch with a simultaneous decrease in the initial heatwave intensity: and oxygen by 1.5-2.0 times , established in the process of research carried out on a two-bath steelmaking unit of the Orsk-Khalilovsk Metallurgical Plant (OXV1I () 0) In an aggregate of capacity t, Grade 17G1SU steel produced (carbon content in jo (finished metal 0.17- 0.19%).

The unit was equipped with six Oxygen tuyeres and six mobile vaulted fuel-oxygen-And-torches, which were switched on by one and all 25 with a decrease in the intensity of the melt purge with oxygen. The blowdown was followed by continuous measurement of the steel temperature and metal and slag samples were taken. Initially, Q At the intensity of the purging of the bath with Oxygen, it was maintained at 32 m5 / h T, the metal was deacidified beforehand in a furnace (silico-margayts) and finally in a scoop at the outlet (ferrosilicon, ferg rotitan aluminum). The research results are shown in table

When smelting steel in a known way (test 9, tables), the required temperature (1600–1620 s) and the specified carbon content (0.17–0s 19%) in the metal at the outlet were not reached, therefore an additional it is heated by burning iron when purging with oxygen before release, and the production of a given carbon content is ensured by supplying coke to the ladle. All that led to an increase in iron loss and metal oxidation and, consequently, to an increased consumption of ferroalloys and a decrease in the yield of the metal

When smelting steel on the proposed55

a method of heating the melt with the introduction of an oxygen-oxygen torch with a simultaneous decrease in the intensity of oxygen purge by 1.5 5, o

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2.0 times when the carbon content in the melt reaches 1.3-1.5%, the metal temperature is not necessary (1605-1620 ° C) at a given carbon content (0.17-0.19%). At the same time, a low content of iron oxides in the slag is reached (13–15%), which indicates a slight erosion of iron and a low oxidation of the metal. This provides increased yield and reduced consumption of ferroalloys for deoxidation. In the case when the heating of the melt with the introduction of an oxygen-oxygen torch with a simultaneous decrease in the intensity of purging with oxygen by 1.5-2S0 times begins when the carbon content in the melt is less than 1.3%, the required melt temperature (1600 - 1620 s) and the specified content carbon (experiment 1 table). At the same time, the content of iron oxides in the slag increases, which ultimately leads to an increased consumption of ferroalloys for steelmaking and a decrease in the yield of good. If you start heating the melt with the introduction of the Aakel fuel-oxygen with a carbon content of more than 1.5%, then the metal is not fully melted when the specified carbon content is reached due to the reduction in the duration of the oxygen purge with maximum mixing of the bath. It also does not provide the necessary heating of the melt (experiment 4 of the table), which increases the oxidation of iron and leads to an increase in the consumption of ferroalloys and a decrease in the yield of good.

A decrease in the intensity of the purge of the melt with oxygen by oxygen by a carbon content of 1.3–1.5% less than 1.5 times (experiment 5 of the table) leads to the fact that under conditions of a decrease in oxygen absorption to the oxidation of carbon during the finishing process, the increased oxygen supply significantly oxidizes iron (the content of iron oxides in the slag increases to 24%), which requires an increased consumption of ferroalloys to deoxidize the metal and reduces the yield. By reducing the intensity of the purge with oxygen | more than 2.0 times (table 8) the melt mixing intensity decreases and deteriorates due to

This heating of the melt (t 1580 ° C), which leads to an additional loss of iron, and ultimately increases the consumption of ferroalloys and reduces the yield of suitable metal.

Example, When smelting in a two-, 17g1SU medium carbon steel grade furnace furnace, the average carbon content of 0.18%) in one bath was filling and heating the charge, pouring iron and simultaneously melting oxygen in the other bath with an intensity of 32 m / t, h “With carbon content in the melt of 1.4%, the heating of the melt began with the introduction of an oxy-fuel torch with a total capacity of 30 MW at 0.45 MW / m and at the same time reduced the intensity of the oxygen purge by 1.8 times. When the carbon content reached 0.58% (0.4% higher than what was specified in the finished metal), the melt was purged with oxygen and the process of refining was carried out with the fuel-oxygen burners turned on until the metal was released. In this case, decarburization to the desired carbon concentration (0.18%) occurs due to the reduction of iron oxide accumulated during purging. After reaching a temperature of 1610 ° C and a carbon content of 0418%, the metal was preliminarily deoxidized with silicon manganese and the final deoxidation in the ladle by ferrosilicon, ferrotitanium and aluminum.

Studies have shown that with a total specific power of the torches of 0.3-0.6 MW / m2, the metal is effectively heated to the required temperature at a given carbon content without additional oxidation of iron. This is evidenced by the reduced content of iron oxides in the slag (J4-15%). This provides, compared with the known method, a reduction in the consumption of ferroalloys by 3.9-, 4.1 kg / t and an increase in the yield of suitable by 1.3-1.4%. When the total specific heat output of the torches of the burners is less than 0.3 MW / m, the amount of heat from the burners fuel introduced into the melt is insufficient and the required heating of the melt

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VA is not provided. The temperature of the metal at the output of 1600–1620 ° C is achieved by additional burning of iron, the metal oxidation increases the content of iron oxides in the slag to 22–24%), which leads to an increase in the consumption of ferroalloys by 2.0–2.5 kg / t and a decrease in yield of 1.0-1.2%. When the specific total heat power of the torches of the burners is more than 0.6 MW / m, the temperature of the roof lining increases to

1650-1750 ° C, which adversely affects the durability of the unit. Reducing the durability of the unit increases repair costs and reduces the performance of the unit.

The application of the proposed method of smelting low- and medium-carbon steel in comparison with the known method / experience 9 of the table) reduces the consumption of ferroalloys for steelmaking by an average of 4 kg / t and increases the yield of 1.3-1.4%. The reduction of metal oxidation provides an improvement in the quality of the metal due to a decrease in non-metallic inclusions.

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Claims (1)

Invention Formula The method of smelting low- and medium-carbon steel in a two-bath steel-smelting unit entails charging and heating the charge followed by pouring iron in one bath and simultaneously blowing the melt with oxygen in the other bath to the carbon content 0.3-0.5% higher than its content the finished metal, heating of the melt with an oxy-fuel torch and deoxidation of the metal, which means that with the aim of reducing. consumption of ferroalloys and increasing the yield of metal, melt heating with an oxyfuel torch is carried out during the purge period, while heating begins when the carbon in the melt reaches 1.3-1.5% with a simultaneous decrease in the purge rate of oxygen by 1.5-2 times from the original. five 0 0.09 1570 26 35.1 88,8