SU1527282A1 - Slag-forming composition for steel-melting process - Google Patents

Abstract

The invention relates to the field of ferrous metallurgy and can be used in the production of steel in aggregates with basic lining. The aim of the invention is to improve the quality of the metal. Slag-forming mixture for steelmaking process contains, wt%: lime (limestone) 56-68

aluminum recycling slag 23-34

carbon material 5-8

Nickel-containing steel waste 2-4. The use of a slag-forming mixture improves the quality of the metal by reducing the concentration of harmful impurities (sulfur by 14-30% and phosphorus by 18-28%), gases and non-metallic inclusions by actively forming a low-melting slag phase. 3 tab.

Description

The invention relates to ferrous metallurgy and can be used in the production of steel in aggregates with primary lining.

The aim of the invention is to improve the quality of the metal.

The preserved slag-forming mixture for the steelmaking process contains lime (limestone), aluminum recycling slag, carbon-containing material and nickel-containing metal waste in the following ratio, wt.%:

Known k56-68

Slag recycled aluminum 23-34

Carboniferous

material5-8

Nickel coder waste

stealing 2-4

Lime (limestone) is designed to form an active basic slag, ensuring the development of the processes of dephosphorization and desulfurization. A decrease in the lime content in the mixture of less than 56 wt.% Leads to a decrease in the basicity of the letter and, consequently, its refining ability with respect to sulfur and phosphorus. When the content of lime in the mixture is above 68 wt.%, The rate of formation of the slag phase decreases. The slag phase at the same time has a high degree of heterogeneity, the solid phase is represented by refractory calcium silicate crystals. All this has a negative effect on ° R

ND

the development of the processes of dephosphorization and metal desulphurization.

Slag of secondary processing of aluminum does not intensify the process of assimilation of lime, and also quickly raises the temperature of furnace slag during exothermic oxidation of aluminum beads, which is especially important under conditions of chromium containing charge redistribution, as this prevents the development of chromium oxidation and the formation of refractory low-active slag. The content of this material in a mixture of less than 23 wt.% Does not provide a high rate of formation of the slag phase, and the latter has a low refining ability. An increase in the slag content of aluminum recycling above 34 wt.% Increases the concentration in the furnace slag, the silicon dioxide phase, while reducing its basicity and, accordingly, JHO, refining properties.

The carbonaceous material is intended to increase the contact surface of the metal and donkey, as well as increase the reducing potential of the latter. This ensures the intensification of the desulphurization and dephosphorization process, the removal of gases and non-metallic inclusions. The increase in the surface of the slag-metal phase occurs due to the release of gaseous carbon monoxide. The increase in the reduction potential of the slag phase in the steel-smelting aggregate prevents the formation of refractory chromic spinels, which reduce the liquid mobility of the slag and, accordingly, the value of its refining properties. The material containing metallic nickel increases the activity of carbon and, therefore, intensifies the action of the processes considered.

Coke, graphite amorphous foundry, crystalline graphite (silver) foundry can be used as carbonaceous material. The use of carbon-containing material in an amount of less than 5 wt.% Reduces the values of the reduction potential of the slag phase, the contact surface of the metal and slag, and consequently, the quality of the metal deteriorates. Consumption of carbon-containing material over 8 wt.%

50

5 o 5 o

five

five

It is associated with a sharp decrease in the concentration of iron oxides in the slag and, accordingly, a decrease in the rate of assimilation of lime, an increase in the degree of slag heterogeneity.

As a material containing metallic nickel, fine chips are used, which are obtained by machining of nickel alloyed steels. The use of a material containing metallic nickel in an amount of less than 2 wt.% Reduces the values of the reducing potential of the slag, the contact surface of the slag metal phase and, accordingly, the quality of the metal. The amount of this material in the mixture of over 4 wt.% Is associated with the formation of a low-active refractory slag.

The use of slag for the recycling of aluminum in combination with the material (scrap and waste of nickel-containing steels) creates conditions in the steel-smelting unit that are close to the conditions of the restorative dephosphorization process. Metallic aluminum slag recycled aluminum deoxidizes furnace slag and reduces calcium from calcium oxide slag melt. Metallic calcium in the conditions of deoxidized slag interacts with the phosphorus of the metal according to the scheme

ZSa + 2P: Ca ,, Pi, binding phosphorus to the phosphide form. However, this process is possible when the concentration of carbon-containing material in the mixture is not more than B wt.%. Otherwise, as is the case in the well-known scheme, calcium metal is bound by carbon to form calcium carbide instead of. In the case of using a known mixture, the process of reducing dephosphorization is suppressed by the formation of calcium carbide. At the same time, the carbon-containing material must intensify the mass transfer processes of the slag-metal phase in order to reduce the concentration of non-metallic inclusions and gases in the metal. The carbon-containing material in the amount of 5-8 wt.% Provides a high rate of mass-exchange processes only in the presence of a material that increases the activity of carbon. The most effective material that enhances carbon activity is nickel-containing. but

increased carbon activity is possible only when using metallic nickel-containing material. The use of nickel-containing material with oxide components (which is, in particular, a waste final ferric nickel final oshaq) is unacceptable, since the reverse process of reducing carbon activity occurs, as well as its expenditure on the reduction of oxides.

A comparative assessment of similar parameters of steelmaking using the proposed and known slag-forming steels was made.

The proposed slag-forming mixture was loaded during the periods of filling-melting (open-hearth furnace), additionally - into an oxidizing furnace (electric arc furnace). Mixture consumption for open-hearth smelting is 6-10 kg / t of steel, electric arc - 5-8 kg / t.

Table 1 presents the variants of the quantitative composition of the mixtures that were used in the smelting of steel; Tables 2 and 3 show the data on the influence of the composition of the slag-forming mixture on the physical properties of the slag and the quality of the metal during open-hearth and electric arc melting, respectively.

Melting steel using the proposed mixture as compared to the known (Tables 2 and 3) improves the quality of the metal by reducing the sulfur concentration by 13.64-27.3% (open-hearth process) and 15-30% (electric arc process), phosphorus - by 18.2 - 27.3% (open-hearth process) and 21.4- 28.6% (electric arc process), oxygen - by 18-26.2% (open-hearth process) and 8-12% (electric arc process), hydrogen - by 11.1-16.7% (the Marten process) and 11.1-18.5% (the electric arc process), nonmetallic

five

0

five

0

5 0 5

inclusions - by 22.7-31.82% (open-hearth process) and 15.8-26.3% (electric-arc process).

A decisive role in achieving a positive effect from the use of the proposed mixture is given to the slag phase, the solidus temperature of which, compared to the known mixture, is lower by 20-40 ° C (open-hearth and electric arc processes), and viscosity - by 0.1-0 , 2 Ns / m (open-hearth process) and 0.15-0.25 N С / m (electric-arc process). In addition, the melting time of full-scale slag samples is reduced by 1-2 mnn (open-hearth process) and 1-3 min (electric arc process).

The use of the proposed slag-forming mixture for the steel-smelting process, in comparison with the known, makes it possible to improve the quality of the metal by reducing the concentration of harmful impurities (sulfur, rebore), gases and non-metallic inclusions by actively forming a low-melting slag phase.

Claims (1)

Invention Formula Slag-forming mixture for the steelmaking process, containing limestone, aluminum recycling slag and carbon-containing material, characterized in that, in order to improve the quality of the metal, it additionally contains waste Nickel-containing steels in the following ratio, wt.%: Known k56-68 Slag recycled aluminum 23-34 Carbonaceous material5-8 Nickel-containing steel waste 2-4 Table 1 is eating 56 68 62 54 71 73 68 67 72.5 34 23 28.5 36 20 75 28 26 15 Scrap and waste of nickel-containing steels (Group B13) was used as a material containing metallic nickel. is eating- 1220 1240 1230 1250 1270 1220 1310 1260 1250 1260 0.4 0.5 0.45 0.7 0.6 0.25, 0.9 0.6 0.55 0.6 6 7 6.5 9.5 9 A, 5 13 9 8.5 eight 2 four 3 R 6 ten eleven four 12.5 table 2 0.027 0.024 0.025 0.030 0.032 0.038 0.034 0.030 0.029 0.045 0.050, 0.046 0.05 0.070 0.048 0.055 0.080 0.076 3.0 3.2 3.1 3.5 3.9 3.4 3.6 A, 2 4.0 0.033 0.061 3.6 0,015 0,017 0,016 0,020 0,022 0,019 0,020 0,022 0,021 0.022 Table 3