SU1686007A1 - Slag-forming mixture for desulphuration and dephosphoration of steel - Google Patents

Abstract

The invention relates to the metallurgy of ferrous metals, namely to steelmaking in electric arc steel-smelting furnaces with a base lining. The aim of the invention is to reduce the content of sulfur and phosphorus in steel. Slag-forming mixture for desulfurization and dephosphorization of steel contains, in wt%: alkaline earth metal oxides 44-47, alkaline earth metal halides 5-20, alumina (III) 26-27 and carbon 6-25. The use of the mixture reduces the sulfur content in steel by 97.3-36.4% and phosphorus by 23.5-41.2%. 2 tab.

Description

The invention relates to metallurgy-ferrous metals, namely, steelmaking in arc steelmaking furnaces with a base lining.

The purpose of the invention is to reduce the content of sulfur and phosphorus in steel.

Slag-forming mixture for desulphurization and dephosphorization of steel contains alkaline earth metal oxides, alkaline earth metal halides, aluminum oxide (11) and carbon in the following ratio, wt.%: Alkaline earth metals oxides 44-47 Alkaline earth metal halides 26 -27 Carbon 6-25 The combined use of oxides and gslsid of alkaline-earth metals, aluminum oxide (111) and carbon provides

a complex effect on the quality of the metal in the following areas: the formation in the furnace of an active liquid-mobile refined alumina slag saturated with carbon, the oxidation potential of which, due to oxygen deficiency, is close to the oxidation potential of the metal melt. On the basis of such created reducing conditions, the loss of halide compounds by evaporation is reduced and the joint removal of sulfur and phosphorus is carried out, the latter being removed according to the scheme of reducing deformation in the form of alkaline earth metal phosphides.

In the case of alkaline earth metal oxides less than 44 wt.%, The ratio of the concentration of these oxides to the concentration of aluminum oxides of the slag phase decreases and, accordingly, its refining properties relative to

to sulfur and phosphorus When the content of oxides is alkaline-earth. metals above 47 wt.% increase the melting temperature and viscosity of the slag, and consequently, its refining ability decreases.

When the content of alkaline-earth metal halides is less than 5 wt.%, The liquid mobility of the slag melt and the concentration of cations of these metals in it decrease, which leads to a decrease in the reduction potential of the slag and, accordingly, to a decrease in the degree of desulfurization and the rate of reduction of the metal. alkaline earth metals more than 20 wt.% leads to the loss of these compounds during evaporation and, accordingly, to a decrease in the physicochemical characteristics of the refining ability of slag .

The content of aluminum oxide (111) is less than 26 May. % leads to an increase in the melting temperature and slag viscosity, a decrease in the degree of de ulfrescence and dephosphorization of the metal. An increase in the content of alumina (III) above 21% by weight reduces the ratio of the concentration of oxides of alkaline earth metals to the concentration of this compound and, accordingly, reduces the refining properties of slag.

If the carbon content is less than 6 wt.%, The reduction potential of the slag phase decreases, which leads to an increase in the concentration of sulfur and phosphorus in the metal. An increase in the carbon content of the sconium over 25 wt.% Is associated with the development of reactions for the formation of carbides of the pinch-ground metals, which further reduces the rate of metal refining from sulfur and phosphorus,

Example, Slag-forming mixture for desulphurisation and dephosphorization of steel is used in the smelting of 110 G13L steel in an electric arc steel-smelting furnace with a base lining. When this mixture is loaded into the recovery period. Its consumption is 5-40 kg / t.

In tab. 1 shows the compositions of the proposed mixture, which were used in swimming trunks in an electric arc furnace: compounds 1 and 2 correspond to the boundary contents of the components, compounds 3-10 to the average content, compositions 11 and 12 to different from

proposed, and in compositions 13-16 is missing one of the components of the mixture.

3 as a well-known mixture of use composition, wt.%: Oxides of alkaline earth metals 40, alkaline earth metal halides 60.

Calcium oxides (lime, limestone) or barium (GOST 10203-78, 6054-75) are used as alkaline earth metal oxides.

Calcium or barium chlorides are used as alkaline earth metal halides (GOST 450-77, 4108-72, 742-78). Sources of alumina (III) and carbon are bauxite (GOST 972-82) and coke (GOST 9093-74) or coal (GOST 7657- 74), respectively.

The results of steel melting using the proposed and known mixtures are given in Table. 2,

The use of the proposed mixture improves the quality of the metal by reducing the sulfur concentration by 27.3-36.4%, and phosphorus by 23.5-41.2%. The temperatures at which the slag begins to melt using the proposed composition of the mixture are lower by 40-50 ° C and viscosity by 0.3-0.5 N s / m2.

In the case of using a mixture with different expenses from the proposed limits of the components (compositions 11 and 12, Table 1), the quality of the metal deteriorates. The use of compounds 7, 8, 11, and 12 does not ensure the formation of fluid-moving slags with low solidus and viscosity temperatures.

When using compounds 13-16 (Table 1), the object does not possess the specified properties, and the goal is not achieved (Table 2).

Claims (1)

Slag-forming mixture for desulfurization and dephosphorization of steel, containing oxides and halides of alkaline earth metals, characterized in that, in order to reduce the sulfur and phosphorus content in steel, it additionally contains aluminum oxide (ill) and carbon in the following ratio Components, wt.%: Alkaline-earth metal oxides44-47 Alkaline-earth metal halides 5-20 Aluminum oxide (III) 26-27 Carbon 6-25