SU1110807A1 - Slag forming mix for producing alloyed cast iron - Google Patents

Abstract

SLAGING MIXTURE FOR PREPARING LEGNED IRON, including vanadium slag, carbon containing material, which, in order to increase the metallurgical activity of the slag, as well as reduce the cost of the mixture, it additionally contains cupola slag and fluorspar, and as carbon-containing material silicon in the following ratio of ingredients, May.%: Vanadium slag 35-50 Cupola slag 30-40 Silicon carbide 10-20 Fluorspar 5-10

Description

00 s | The invention relates to the metallurgy of ferrous metals, namely to the compositions of spacoobrazuntsih mixtures used in the smelting of low- and medium-alloyed iron with the extraction of alloying elements from slag. A known flux for doping a metal with vanadium, containing calcium fluoride and vanadium pentoxide tl. Conducting an electroslag conversion under the flux of this composition contributes to the recovery of vanadium from slag. By varying the concentration of vanadium pentoxide in the flux, it is possible to regulate the concentration of reduced vanadium in the metal. However, the presence of an increased amount of calcium fluoride in the flux makes it very expensive, and the absence of a reducing agent makes the treatment process ineffective. Closest to the proposed is the slag-forming mixture used in the repartition of vanadium slag 2, containing, in wt%; Vanadium slag 55-65 Dolomite unburned 27-33 Coke is thrashing 8–12 The disadvantages of the mixture are its n as reducing ability with respect to vanadium at low temperatures (and for cast iron they are typical), since the carbon in the mixture is an effective reducing agent only at temperatures above 1400 ° C and, as a consequence, a slight increase in the content of the alloying element in the melted metal. The aim of the invention is to increase the metallurgical activity of the slag, as well as reduce the cost of the mixture. The goal is achieved by the fact that a slag-forming mixture to produce doped iron, including vanadium shpak, carbon-containing material, additionally contains cupola slag and fluorspar, and as a carbon-containing material - silicon carbide in the following ratio of ingredients, wt.%: Vanadium slag 35- 50 Spac cupola 30-40 Silicon carbide 10-20 Fluorspar, 5-10 The presence in the composition of the slag-forming mixture of a specified number of components contributes to the flow of recovery processes and ensuring is to obtain high quality without the use of iron-carbon alloys in the charge expensive ferroalloys. The positive effect of the introduction of the composition of the slag-forming mixture of silicon carbide lies in the fact that it ensures the effective course of the reduction reaction of vanadium, titanium, chromium, iron, silicon and manganese from the oxides forming the slag melt. Moreover, if the reducing ability of silicon to higher than that for carbon, then in the temperature range above 1400 ° C, the carbon activity significantly exceeds the silicon activity, thus ensuring the task of intensive reduction reactions in the entire temperature range of the melt. The combined use of carbon and silicon will compensate for their shortcomings as reducing agents in continuously changing conditions. When the content of the silicon carbide slag-forming mixture is less than 10 wt%, the conditions for reducing the alloying elements from their oxides are not provided. The increase in the content of silicon carbide more than 20% is impractical because it leads to the content in the slag fluxing and refining components and increases the cost of the mixture. The reduction products of the oxides contained in the slags are Me, SiOj and SP, resulting in a decrease in the melt of metal oxides. slag is formed with an increasing concentration of SiOj. STo leads to an increase in the viscosity of the slag and deterioration of the kinematics of the reduction of elements from their oxides. To compensate for the effect of the resulting silica on the viscosity of the slag, fluorspar was introduced into the mixture. Calcium oxide in the composition of the slag composition of the mixture also has a positive effect on reducing the viscosity of the slag. Fluorspar promotes the active course of the desulfurization process. The content of fluorspar in a mixture of less than 15% does not provide a sufficient degree of desulfurization, an increase in the content above 20% leads to an increased release of fluoride compounds into the atmosphere and makes the mixture more expensive,

In the composition of the proposed slaughtering composition use vanadium slag containing, in wt.%: UgOu 21-25; Si02 14-18, RvoBsch 32-36, TiOj 7-10, MpO 8-10, 3-4, CaO 0.8-1.4; MgO 2-4; 1.2-1,

The use of vanadium slag is due to the presence of such oxides in it, which make it possible to obtain alloyed cast iron of higher quality and special purpose. A change in the content of vanadium slag above and below accepted limits significantly affects the doping process, which is confirmed by practical research, and the limits can be considered optimal.

Introduction to the composition of the slag-forming mixture of cupola slag, which is a waste of production and is not in practical use s

one industry, helps reduce the cost of the mixture. At the same time, the cupola slag includes oxide, which, in combination with the other components of the mixture, provides slag with properties that allow a positive effect on the metallurgical smelting process at a certain viscosity and temperature.

Burnt slag contains, wt%: SiOj, 46-50; 12-18; FeO 20-24; CaO 10-14i MgO 2-3; MnO 0.4-0.6.

Measuring the content in the mixture of cupola slag outside the proposed limits leads to deterioration of the properties of the smelted slag due to changes in the content of other ingredients in the slag-forming.

In tab. 1 shows data for |. The viscosity and melting point of the spike obtained from the proposed slag-forming mixture reflect the degree of influence on them of the contents of cupola and vanadium slags.

Table D

As can be seen from the table. 1, the slag has a sufficiently high melting temperature. And viscosity, which ensures that the pig iron is treated at 1630-1 ° C. C. These indicators ensure the presence of silicon oxides and apkishni in the cupola slag due to its high melting points and high viscosities. oxides contained in vanadium slag. Introduction to the composition. the mixture of fluorspar in the complex with the other components provides slag with the necessary properties. In tab. 2 lists the composition of the tested slag-forming mixtures, Note. Mix Options

Tests of the prepared mixtures were carried out as follows.

From the mixture, a slag bath was introduced in an electrofishing furnace, and then, in a continuous process, shiktovps materials were filled into the furnace with the following calculated composition,%: C 3.15, Si t, 89i Mp 0.67} S 0, .12; P 0.14. Melting was carried out in a semi-industrial single-phase electroslag furnace with non-consumable graphite electric table 2

a rod and a crucible made also of a graphitized electrode. The furnace1 was connected to a furnace transformer TPO 250/40 pc.

The chemical composition of the pig iron melted using the proposed mixture in comparison with the use of a prototype mixture for this purpose (the experiments were carried out under the same conditions) is given in Table. 3

Table 3 1-3 relate to the prototype mixture. How do you see from the table. 3,. The cast iron heading using the proposed mixture is almost twice as effective both in terms of restoring alloying elements and in terms of desulfurization. In addition, the application of the proposed mixture ensures that the content of carbon, silicon and manganese in the iron is almost constant, while using the prototype, the content of these elements is reduced. This is due to the positive effect of carbide / srymni, which, having a high melting point and close to nsakak density (3.2 g / cm), is in the slag layer in a heterogeneous state, retaining a high reactivity. Silicon carbide

The continuation of Table 3 is characterized by a high resistance to oxidizing atmosphere, which decreases its oxidation rate and makes it effective diffusion; deoxidizing and reducing. Thus, the remelting of gray iron under the slag from the proposed mixture makes it possible to produce cast iron doped with vanadium, titanium and chromium. Technical and economic effect from the use of the proposed invention. It mainly consists of the cost items for the replacement of fresh foundry and natural cast iron with the return of own production and can be 16-18 p. per ton of pig iron produced.

Claims (1)

SLAG-FORMING MIXTURE FOR PRODUCING DOPED IRON, including vanadium slag, carbon-containing material, characterized in that, in order to increase the metallurgical activity of the slag, as well as reduce the cost of the mixture, it additionally contains cupola slag and fluorspar, and as carbon-containing silicon material the following ratio of ingredients, May. %: Vanadium Slag 35-50 Cupola slag 30-40 Silicon carbide 10-20 Fluorspar 5-10 8 ω from § >