SU834151A1 - Steel manufacture method - Google Patents

Description

(54) METHOD OF GETTING STEEL

I

The invention relates to ferrous metallurgy and can be used in the production of high quality steel.

A known method for producing steel with a low sulfur concentration is by treating the steel in the ladle with the release of synthetic slag, which is prepared in a separate slag-melting unit il.

The closest to the proposed technical essence and the effect achieved is the method of steel production, including smelting in a steel-smelting unit, subsequent melt evacuation, oxidation of impurities with gas, treatment with neutral gas and desulfation, with desulfurization in the amount of 1.0-15, 0 kg / t is introduced into the melt in the process evacuated simultaneously with the processing of neutral gas 2 ..

However, the known method does not provide a high speed and degree of desulfation and requires a large consumption of desulfator. o due to the fact that the removal of sulfur in steelmaking processes proceeds mainly by the reaction

(CaO) 4 IS} (CaS) h Oj (I)

From the expression of the equilibrium constant

reaction follows

.r / oS) (/ oO, (21

K-ChSad 1

where K is the equilibrium reaction constant;

0 - ir, .d-activity of slag components;

ift n f d -equality coefficients

cops metal.

Thus, to achieve a high degree of desulfurization, a low concentration of oxygen in the melt is required, and the known method maintains a relatively high concentration of oxygen, since, along with the operation of desulfurization, oxidation of impurities is oxidized with an oxidizing gas. In addition, in a known method, desulfurization proceeds at a low speed, since it involves the use of a solid desulfurizer. In this case, the magnitude of the interfacial surface of the metal desulfurizer, i.e., practically, the degree of grinding of the material, acquires great importance. In the known method, a relatively coarse fraction material is used, since under the conditions of a working vacuum pump, the powder materials are removed from the vacuum chamber. Mixing the metal by purging with argon does not eliminate this drawback, therefore, to achieve a high degree of sulfur removal, a high desulfurizer consumption is required (up to 15 kg / ton). .. The purpose of the invention is to increase the speed and extent of sulfur removal and reduce the consumption of desulphurization when desulphurizing steel in the after-furnace vacuum process. This goal is achieved by the fact that a desulphurizer in an amount of 0.5-2.0 kg / t is introduced into the deoxidized metal simultaneously with coke or a desulphurizer is applied to the surface of coke, which is introduced into the vacuum chamber during vacuuming. An increase in the degree of desulfurization is provided by introducing a desulfurizer into the deoxidized metal simultaneously with coke. Increasing the carbon concentration in the catalyst leads to an increase in the activity of sulfur, which contributes to a decrease in its concentration in the metal. In the zone of coke dissolution under vacuum conditions, a high concentration of carbon, a low concentration of oxygen, a high concentration of calcium oxide, and also intensive mixing due to the release of gaseous carbon monoxide directly in the reaction zone is achieved. All these factors contribute to the achievement of low sulfur concentrations. Since coke is a porous material, the deposition of a desulphurizer on its surface at the same time increases the reaction surface and the contact of reacting substances, which significantly increases the sulfur removal rate and requires a lower desulfurizer consumption (0.5-2.0 kg / t). Less than 0.5 kg / ton of desulphurizer is undesirable, since with a small amount of input material, the relative value increases.

Offered with the application of the annotations to the surface of coke

Known using lump lime

Classic open-hearth open-hearth open-hearth furnaces with a synthetic slag

Oh, O18

0.027 0.033

0, O14 its losses, for example during transportation, loading and other technological operations. An increase in the desulfurizer consumption of more than 2.0 kg / t is also undesirable, since at additional costs this practically does not lead to an increase in the degree of sulfur removal. The method is most expedient to carry out at circulating vacuuming of steel, since the raw materials are introduced directly into the metal (there is no slag phase in the vacuum chamber), and high CaO activity is achieved, close to unity, which according to equation (II) increases the degree of removal sulfur. In this vacuuming method, it is possible to remove the reaction products from the vacuum chamber into the slag phase in the ladle. Due to the passage of material through a high metal column, the interfacial contact surface with the metal increases substantially, contributing to an increase in the degree and speed of sulfur removal. Example. It conducts two steel melts St40H. The steel is smelted in a 120-ton open-hearth furnace, followed by a vacuum using a fully deoxidized metal circulation method and a carbon content of 0.10% below the target. In the vacuum process, coke in the amount of 1.5 kg / t is introduced into the metal from the bins of the vacuum chamber and lime in the amount of 1.5 kg / t is introduced into the metal desulfurator. In one smelting, lumpy lime is introduced, in the second smelting lime is applied to the surface of the coke. For this, a solution of a measured amount of lime is poured over coke and calcined in a drying oven at a temperature of 700 -. The results obtained in comparison with the classical open-hearth method of steel production and with steel processing in the ladle with the release of synthetic slag are presented in the table.

As can be seen from the table, the proposed method with a significant reduction in the flow of the desulfurizer provides a high degree of sulfur removal and can compete on this indicator with the treatment of steel in a ladle with synthetic slag.

Using the proposed method for producing stainless steel instead of the currently used method including processing of synthetic; with a cinder slag followed by vacuuming, significantly simplifies the technological flow of production, since it eliminates the use of a slag-smelting unit and significantly reduces the freight flows in the workshop, especially during the production of smelting. The economic efficiency comes from the difference in the cost of steel processing with synthetic slag (6-7 rubles / ton) and the cost of preparing coke and lime (I-2 rub / ton) and is 4.0-5.0 rubles. on I t steel.

Claims (2)

1. A method of producing steel, including smelting it in a steelmaking unit, subsequent evacuation, desulfurization during the evacuation process, characterized in that, in order to increase the speed and extent of sulfur removal, reduce the desulfurizer consumption, the desulfurizer is introduced into the deoxidized steel simultaneously with 0 coke , 5 - 2.0 kg / t. 2. A method according to claim 1, characterized in that the desulfurizer is applied to the surface of the coke, which is introduced into the vacuum chamber during the evacuation process. Information sources, taken into consideration pri.expertise .one. Voinov S.G., Shalimov A.G., KalinickiK. E.S. and Kosov L.F. Refining became synthetic slags. M., “Me-g Tallurgy, 1970, p. 464. 2. USSR author's certificate number 551374, cl. C 21 C 5/52, 1977.