SU954431A1 - Method for melting steel - Google Patents

Description

The invention relates to ferrous metallurgy, more specifically to methods for smelting vanadium-containing steels in electric arc furnaces.

There is a known method of steelmaking using vanadium from converter vanadium slag, in which vanadium slag is introduced into the filling or during the period of melting. Together with lime and reducing agent in a ratio of 1: (O, 5-1, 5): (O, 1-0 5) 1.

The disadvantage of this method is the increased content in the slag of melting vanadium and manganese oxides, in connection with which it becomes difficult to download oxidizing slag.

In addition, the resources of vanadium slag in the country are limited and do not provide for the production of the required volume of vanadium-containing steel of increased strength.

The closest to the present invention is a method of steel smelting, including melting of the charge, doping with vanadium due to vanadium-containing materials, including vanadium scrap metal, fine-tuning and release 2.

The disadvantages of this method are the relatively low absorption of vanadium — 89.5%, increased manganese loss when smelting high-manganese steel by fusing or remelting — up to 15%; the increased content in the slag melting of vanadium and manganese oxides is up to 1.9% and 36%, respectively, due to which it becomes

10 impossible download of melting slag.

The purpose of the invention is to increase the recovery of vanadium and manganese from the melting slag.

15

The goal is achieved by the fact that according to the method of steelmaking, including the straightening of the charge, doping with vanadium due to vanadium-containing materials, including

20 vanadium metal extractor, finishing and production according to the invention, vanadium metal extracting, lime or limestone and ground coke in the ratio 10: (4-7): (O, 4-0.7U

25 in the amount of 1-15% of the weight of the metal filling machine, in equal portions at the beginning and in the middle of the filling.

This ratio of the components of the mixture (vanadium metal outgrowth, iz30 Vest and molten coke) ensures a sufficiently high slag basicity, a low amount of oxides in it, a decrease in manganese losses, an increase in the absorption of vanadium and a decrease in the content of harmful impurities in the finished metal. At a decrease in the concentration of one of the components of the mixture, the maximum effect is not achieved in the recovery of vanadium from slag and obtaining high-quality metal, an increase in concentration leads to an unnecessary consumption of materials and an increase in the cost of steel. The effect of the mixture on the assimilation of alloying elements is given in Table. 1. The carbon contained in the metal phase of the vanadium metallootsev, due to the close contact with iron oxides and vanadium from the slag phase, contributes to their recovery and transition into the metal, burning out to rather low values. However, this carbon is not enough to completely reduce oxides, therefore, according to the proposed method, ground coke should be introduced into the furnace during the filling period. The advantage of using coke and the quality of the reducing agent is that the gaseous products of the reduction reaction do not create an additional amount of slag. In addition, the basis of the slag does not decrease. The content of carbon in the metal after the charge is melted is within the brand composition. The content of vanadium and manganese oxides in the slag melting is reduced to 0.2-0.42 and 18-23%, respectively, due to which it is possible to partially download this slag without significant loss of manganese and vanadium. Downloading part of the slag helps to reduce the content of sulfur and phosphorus impurities in the metal, which, in turn, allows the use of less expensive FMN78K carbon ferromanganese with increased phosphorus content (up to 0.45%) for doping. The optimal amount of the mixture is established from the following conditions. The introduction of the mixture in the amount of 1.0% provides the concentration in the steel of vanadium (0.05%), which creates a noticeable effect of improving the quality characteristics of the metal. When the mixture is introduced in an amount of 15%, an excessive amount of slag is formed in the furnace, which increases the loss of alloying elements impedes process control and increases power consumption and melting time. As for the introduction of the mixture in equal portions at the beginning and in the middle of the filling, the efficiency and feasibility of this technique are determined by the conditions of slag formation and technology; filling period gichnostyu. In this case, the formation of slag is ensured since the formation of the first portions of the liquid metal and the gradual increase in the amount of slag with an increase in the volume of molten metal. Early and consistent slagging creates favorable conditions for the rapid passage of reduction reactions and more complete assimilation by the metal: manganese and vanadium. Example. In the 6-tonne main electric arc; the furnace produced 110113FL steel. In the first two swimming trunks, according to a known method, metal extractors are loaded into the furnace in the middle of the filling in the amount of 800 kg mixed with lime. Steel scrap and cast iron - by 6000 kg, ferromanganese FMN1.5 by 1000 kg. The vanadium content in the metal extractor is 2.6%, the slagging is 26%. In the next 4 heats, 800 kg of a metal extractor mixed with 400 kg of lime and 40 kg of ground coke are loaded in equal portions per day. Furnaces and in the middle of the filling, consisting of 6000 kg of scrap and 1060 kg of ferromanganese, of which 500 kg of Fin78K. Technological parameters of the melting process are given in table. 2. From table. 2, it can be seen that the content of vanadium and manganese oxides in the slags obtained during the smelting of high-grade steel using the proposed method is lower than the known. The basicity of the slag according to the proposed method is higher, and the content of phosphorus and finished steel is lower than in the known method. Vanadium metal absorption reaches 97% versus 89% by a known method, while the production of high-quality vanadium-containing steels is expanded. The average absorption of manganese is 91% versus 85% in the known process, thereby saving this valuable alloying element. .J Production of a vanadium-containing flock by the proposed method will provide a significant economic effect by saving vanadium and manganese.

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Claims (2)

1. USSR author's certificate number 358374, cl. C 21 C 5/52, 1977. 2. USSR Author's Certificate No. 665003, cl. C 21 C 5/52, 1977.