SU865922A1 - Method of smelting steel and alloys - Google Patents

Description

(54) METHOD FOR MELTING STEEL AND ALLOYS

The invention relates to ferrous metallurgy, namely, to the technique of producing steel and joints in main electric furnaces by fusing under one slag. There is a known method for smelting steel and alloys in arc furnaces, the conclusion being that melting and oxidizing steam (}} dosing is carried out under lime (after-slag earth slag, and after downloading it, lime or lime-slag ij is induced). unstable slag regime during the period of smelting, carburization, lawn, metal shrinkage and, moreover, increase of the charge of the metal charge due to the download of lime-alumina slag. There is also a method of smelting alloys by fusing one lime-alumina slag, concludes with the use of a mechanical mixture of lime and technical alumina to 1OO kg each to obtain an approximate calculated slag composition of 50% Av. CaO. 5-7 minutes after turning on the furnace, the additive of this mixture is started in the furnace under the electrodes The entire slag mixture must be set into the furnace at the beginning of the melting period. The slag mixture is not sitting on the hearth and into the basket — it does not sit down kgg 2. The disadvantage of this method of smelting is that the efficiency of the early (5-7 min after turning on the furnace) mechanization is low ical slag mixture under the electrodes. It is known that (HCO-alumina slag of composition 5О% СаСН-50% АВ О is made up of a mechanical mixture of lime with a fraction size of about 30 mm (the use of powder is prohibited) and technical alumina using T-OO powder fractions. Introduction of slag mixture under electrodes, when there are no boilers yet, leads to the flow of alumina, due to its low flowability, to bring the furnace and the slopes of the settling furnace to charge on top of the charge. After the wells are melted, the lime-alumina slag of the composition far from the 50% CaCN-50% Le 02, therefore, of a refractory, heterogeneous slag. Uneven burning of arcs in such a slag mode leads to gas saturation, carburization, and increased sludge of the charge stock. The ingress of a significant amount of high-flowing alumina of the mechanical slag mixture under electrodes, but on the slopes and bottom of the furnace leads to yus overgrowth due to the formation of refractory aluminomagnesian spindles with a melting point and lengthening of the melting time due to the laborious cleaning of overgrown slopes in the furnace bottom. The purpose of the invention is to reduce the carbon content, gas saturation, metal charge fines, improve the quality of the metal being produced and the technical and economic indicators of smelting. The goal is achieved by the fact that 2O-6O% of the slag mixture is introduced into the basket with the mixture and (or) on the furnace bottom before charging the mixture as a pre-alloyed mixture, and the remaining part of the slag mixture is introduced into the furnace after melting 52 kg / ton of filling in each well, and after the main mass is melted, the decomposition of electrodes is started, and it is stopped 10–30 minutes before the end of the melting period. During the smelting process, wells are melted and pools of liquid metal are formed. From a pre-alloyed slag slag of 5O% CaCH-50% ® poured into a basket with the charge and (or) on the side of the charge, a lime-alumina slag similar in composition to the slag of 5O CaO + 5O% ABO having a low temperature is formed melting (l / 1390 C). This is very important, since slight deviation from the above composition towards a higher content of one of the constituents leads to heterogeneous slag, due to its significant increase in the melting temperature, as a result, to unstable arc burning, carbonization of the metal, high saturation and increase of the metal charge. From the moment of the heating of the wells, the wells are determined by the steady burning of the arcs and the stopping of the movement of the electrodes down into each colo or disintegration of the electrodes after melting the bulk of the filling mass and introducing the mechanically mixed mineral fiber mixture. The introduction of slag mixture into the melted well contributes to the complete assimilation of the mixture, especially the bath's linozem, to the preservation of the composition of the slag, which is very close to the composition of 50% CaO + O%, to prevent overgrowth of bottom and slope. The amount of fused slag introduced into the basket with the charge and (or) on the furnace bottom before charging the charge is determined by the chemical composition of the charge, its overall size, condition of the furnace lining p is within 20% -60% of the total amount of slag introduced into the furnace during the melting period. When less than 20% of the slag mixture is introduced into the furnace, the amount of slag is not enough to form a slag cover at the beginning of the melting period, preventing the liquid metal from carburization, gas saturation and increased carbon loss. In addition, with a small amount of slag, the arc is unstable, which increases the melting time of the metal. When the amount of fused slag introduced into the basket with the charge and (or) on the furnace hearth before charging the charge is more than 6O%, great difficulties are encountered in early production of liquid slag during the initial melting period, and the melting period increases due to the heat exchange disturbance in the furnace. The addition of the remaining part of the slag mixture during the period of melting of the wells after melting is dictated by the necessity of introducing slag into the wells on the liquid metal to obtain slag, which is very similar in composition to 5O% CaO + 5O%, and excluding the flow of alumina to the furnace and the furnace slopes, and, as a result, their zarapshvani. The psfo of the slag mixture, which is located after the wells are completed, are determined by the conditions of the period of completion that are determined experimentally in industrial smelting. When small pieces of charge are mixed into the process, the process proceeds forcefully, in this case the portions of the sitting down mixture should not exceed 2 kg / ton of filling introduced into each well or into the disintegration of the electrodes. With a large size and a long melting period, the amount of the slag mixture is not less than O, 5 kg / ton of Zbalki. From the moment of the penetration of the wells, both the mechanically mixed slag mixture and the previously fused slag can be applied onto the metal mirror.

The limitation of the final time of the addition of the slag mixture is due to the formation of a liquid, homogeneous slag by the end of the melting period (the beginning of refining).

The time of the last addition of the slag mixture is up to the end of the melting time of 1030 minutes. When portions of the slurry mixture are introduced into the furnace, 0.5 kg / ton of filling in each well, and after the bulk of the bulk material is melted into the decomposition of the electrons, less than 10 min With the introduction into the furnace of portions of the slag mixture of 2 kg / ton of filling no more than 30 minutes.

The method was tested in the production of a chromium-nickel metal with a carbon content of up to 0.10% in a 5-t arc furnace with the main lining using 5O% of its own waste in the charge.

Example. In the furnace basket, one kilogram of slag mixture, which is 2% of the total amount of this mixture, introduced during the period of smelting, previously melted slag mixture of 50% AK / 0. After the wells are pored, and after the main mass is melted fillings in the decomposition of electrodes, portions of 2 kg / ton each of the fillings injected mechanical and alumina-alumina slag mixture in the amount of 128 kg per smelting. The mechanical slag mixture is ceased to be introduced into the furnace for 30 minutes before the end of the melting period. Then the metal is refined and released from the furnace according to the existing technology at the plant.

PRI mme R 2. Melting is carried out in the same manner as in Example 1, except that 96 kg / ton of filling (6O%) of the previously pre-calcified lime-alumina-ized mixture is introduced into the basket. Then, after the wells were melted down, a mechanical lime-alumina mixture was introduced into the furnace in portions of O, 5 kg / ton of filling in the amount of 64 kg per smelting. The mechanical slag mixture is ceased to be introduced into the furnace 10 minutes before the end of the melting period.

PRI me R 3. Melting is carried out in the same manner as in Example 1, only the pre-fused limestone mixture is introduced into the basket in an amount of 64 kg (4O%), after the wells are melted, the furnace is introduced into the furnace.

forged-alumina mixture in portions of 1.25 kg / ton of filling in the amount of 96 kg per smelting.

PRI me R 4, Melting are the same as in example 3, only the pre-fused lime-alumina mixture is given to the furnace.

For comparison, melts of the same metal were carried out on the same charge using the existing technology at the plant. After charging the charge, after 5–7 minutes of switching on the furnace, the additive of a mechanical lime-alumina slag mixture, consisting of 80 kg of technical alumina and 80 kg of lime, is started in the furnace under the electrodes. The entire slag mixture is introduced into the furnace at the beginning of the smelting period. No slag mixture is added to the basket and the bottom. Next, the metal is refined and released from the furnace.

The table shows the averaged data on the proposed and well-known smelting technologies of the EP-199 alloy, from which it can be seen that the proposed method allows to reduce carbon content, gas-richness and waste of the metal charge, to improve the quality of the metal and technical and economic indicators of smelting.

Improving the assimilation of the metal charge and stabilizing the markings make it possible to work at the lower limits by means of scarce, expensive elements, which significantly improves the technical and economic indicators of smelting.

The calculation shows that smelting, such as alloy, EP-1O9 by increasing the assimilation of the charge from 6.5 to 3.75 kg / ton of metal on average will save nickel 2.4 kg / ton, chromium O, 7O kg / ton, tungsten 0.35 kg / t, which will amount to, at a price of 21 kg, nickel H-19, 3.92 rubles, chromium X-1-1, O7 rubles, and tungsten of metal, 14.45 rubles, 15.2 rubles. / ton of metal.

The stability of marking in the smelting process of the proposed method will reduce the calculated chromium and tungsten content from 19.7O to 19.50%, from 10.0 to 9.7O%, respectively, which will save 45.5 rubles / ton.

In sum, this will provide an economic effect of about 60 rubles / ton of alloy.

The proposed method of smelting steel and alloys can be carried out in the production of high-frequency steels and alloys in factories of high-quality metallurgy.

Offered technology 0,01194,5

0.050

0,01134,5 0,052

0, О1О83.0 0, О45

0, O1153, O 0.040

I know technicals 0,01246.5

Claims (1)

0.06-0.10 Notes Formula of Invention A method of smelting steel and alloys, including smelting metal under calc-alumina slag with an additive of mechanical slag mixture during the period of melting into a furnace, characterized in that, in order to reduce carbon content, gas saturation and coal of charge , improving the quality of the metal and the technical and economic indicators of melting, 2O-60% of the slag mixture is introduced into the basket with the charge and (or) on the bottom of the furnace before filling the charge in the form of a pre-alloyed mixture, the rest 13.5 36.8 180 e: When carbon is obtained from the melt, 0.07 metal is rejected due to the subsequent poor plasticity of the slag mixture is introduced into the furnace after the smelting of the wells with a powder of 0.5-2 kg / ton of filling in each well, and after the main mass of the filling is melted electrodes, and stop for 1OZO minutes before the end of the melting period. Sources of information taken into account during the examination 1. USSR author's certificate No. 52О406, cl. C 21 C 5/52, 1976. 2, Sbartt technological instructions for the smelting of steel and alloys in the main electric arc furnaces. Plant Elekgrostal /, 1973, s, 348.