SU1693079A1 - Method of producing complex flux - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular to methods for producing fluxes used in steelmaking. The purpose of the invention is to increase the refining ability of the flux, reduce the cooling effect when it is used, increase the yield of the suitable one. The method involves mixing the limestone with the additive and pouring the resulting mixture with slag, carbon-containing material is added as an additive, and the charge layer is poured with molten welding slag at a mass ratio of limestone, carbon-containing material and welding slag, respectively (1-1, 2): (0.8-1): 3. The method provides an increase in the degree of steel de- phosphorization from 12 to 20, increases the yield of the suitable one from 0.099 to 0.284%, reduces the cooling effect from -25 to -5 ° C. 2 tab. 5 fe

Description

The invention relates to ferrous metallurgy, in particular to methods for producing fluxes used in steelmaking.

The purpose of the invention is to increase the refining ability of the flux, reduce the cooling effect when it is used and increase the yield.

The method involves mixing lime with the additive and pouring the resulting batch of slag with slag, carbon-containing material is added as an additive, and the charge layer is poured with molten welding slag at a mass ratio of lime,

carbon material and welding slag (1.0-1.2) :( 0.8-1.0): 3.

The method of producing flux is based on the complete transformation of lime into lime due to the thermal and chemical effects on it of high-temperature slag melt (i.e., molten welding slag). At the same time, the surface layers of lime are saturated with iron oxides of slag, forming more fusible calcium ferrites. The carbon-containing material due to the heat exposure of the high-temperature slag melt becomes anhydrous, loses volatiles, but retains carbon due to the heat

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without air access. As a result of processing the mixture of lime with a carbon-containing material with high-temperature slag melt, a complex flux is obtained, which is a porous mass of slag with numerous inclusions of carbon and lime saturated in the surface layers with iron oxides.

The use of molten welding slag as a reagent (obtained in the heating wells of the blooming shops) is due to its increased reactivity (high content of iron oxides) and low content of impurities (sulfur and phosphorus) harmful for steelmaking. The use of such slag to produce flux reduces the consumption of solid oxidizing agents (iron ore, scale, etc.). Since welding slag has a very low content of sulfur (less than 0.05%) and phosphorus (less than 0.05%), it provides a high refining ability of the flux.

In addition, the iron oxides of the welding slag, the transition to the open-hearth slag, limit the oxidation of the iron of the bath, which is observed with a decrease in the carbon content in the melt. This helps to increase the yield.

The use of carbon-containing material as an additive is due to the use of carbon as a coolant in steelmaking. When the complex flux comes into contact with the steelmaking bath, carbon passes (dissolves) into the metal, and then is oxidized to release thermal energy, which compensates for the cooling effect of the additive.

The use of carbonaceous material increases the carbon content of the steelmaking bath, limiting the oxidation of iron. It also contributes to increasing yield.

With a ratio of limestone to carbon-containing material and welding slag less than 1, the content of CaO in the complex flux decreases, that is, its refining ability decreases.

With a ratio of limestone to the carbon-containing material and welding slag of more than 1.2, no complete conversion of limestone to lime is provided. The use of such a complex flux is not efficient enough due to the high cost of thermal energy for decomposition of the limestone.

When the ratio of carbon-containing material to lime and welding slag is less than 0.8, the cooling effect of the additive is not fully compensated due to the insufficient amount of thermal energy from the oxidation of carbon of the complex flux.

With respect to carbon

material to lime and welding slag more than 1 decreases the refining ability of the complex flux due to the reduction of iron oxides in the slag, additional heating of the metal due to the carbon-containing material is observed.

Lime is mixed with the carbon-containing material (coking) and the resulting charge layer is poured with molten

welding slag. The resulting complex flux is used to smelt steel in the open-hearth process.

PRI me R 1. Known to size up to 40 mm (81 kg) was mixed with coke nut with a size of up to 25 mm (81 kg), covered in a slag layer up to 80 mm and poured 270 kg of welding slag composition,%: SI02 9.80; 4.87; CaO 4.40; MDO 7.80; P 0.03; S 0.05; iron oxides else. AT

for 2 min, intense boiling of the slag mixture occurred. After the slag hardened, further gas evolution was observed, accompanied by

by cracking the resulting complex flux. After 30 min, pieces of complex flux were removed from the slag. Chemical analysis indicated complete conversion of lime into lime. The resulting complex flux was placed in a open-hearth furnace during the period of refining

instead of scale and lime. 4.5 minutes after the introduction of the 1% complex flux in relation to the kiln of the furnace, a liquid-mobile slag is formed, the basicity of which increased from 2.0 to 2.05, containing

the amount of FeO was 12-16.7%, the degree of dephosphorization increased by 17 units, the temperature of the metal did not change, the yield increase was 0.284%.

PRI mme R 2. Known to (90 kg), mixed with coke nut (81 kg), with the same thickness of the layer poured 270 kg of molten welding slag. Analysis of the complex flux showed that it contains,%: CaO 13,6; FeO 47.6; C 18.4;

the rest is 20.4. The resulting complex flux in the amount of 1% of the furnace charge was placed in the open-hearth furnace during the period of a clean bale of finishing. After 5 min, the degree of dephosphorization of Lp (P20s) / P increased by

19 units, the temperature of the metal remained unchanged. The increase in yield was 0.278%.

The chemical composition of the materials of the initial mixture and their consumption are given in table.1.

The results of the experimental heats are given in table 2.

From the results of Table 2 it can be seen that the complex flux obtained by the proposed method improves the degree of dephosphorization of steel, eliminates the cooling effect of the additive.

The resulting complex flux can be used in steelmaking in open-hearth furnaces, converters and electric furnaces instead of solid oxidizers, limestone and lime, as well as complex fluxes based on them.

The technical and economic effect of using the method is to increase the refining capacity of the slag, save solid oxidizers, lime, recycle the welding slag from the heating wells of the blooming shops, increase the yield of the suitable one.

Claims (1)

The invention method of producing complex flux for steelmaking, including mixing lime with the additive and pouring slag mixture, characterized in that, in order to increase the refining ability of the flux, to reduce the cooling effect during its use and to increase the yield, it is used as an additive the carbon-containing material, and the charge layer is poured with molten welding slag at a mass ratio of limestone, carbonaceous material and welding slag, equal to (1.0-1.2): (0.8-1.0): 3. Open-hearth slag