SU1211300A1 - Method of steel melting in open-hearth furnace - Google Patents

Description

This invention relates to metallurgy, namely steel production in open-hearth furnaces.

The purpose of the invention is to reduce the consumption of ferrosplays and improve the quality of the metal.

The proposed method is carried out in the following manner.

Waste abrasive production, together with electrolytic slag remelting slag, the ESR is introduced into the furnace 5–20 min before the launch of iiee metal. Abrasive production waste with-t contains 20-45% silicon carbide, 10-25%: carbon, from .30 to A0% silica and less than 5% basic oxides. They are lumpy, the size of pieces is from 5 to 100 mm. Formed in the production of black silicon carbide.

As shown by the results of a semi-industrial study (Table 1), among a number of secondary materials from this production, waste with the indicated composition is most suitable for stabilizing the oxidation of vanya, since, along with a strong deoxidizing agent, silicon carbide, which contains an element in the oxidation of which a sufficient amount of gaseous substance is present. .

When loading abrasive production wastes. Less than 5 minutes before the release of smelting, the deactivation of the bath and the dilution of the slag proceed incompletely. The reduction of slag oxidation is insignificant (less than 1%), and the degree of desulfurization is almost zero (Table 3). The high oxidation of the bath causes a decrease in the consumption of deoxidizers introduced into the ladle for the final deoxidation of the metal. A reduction in the consumption of ferroalloys and the reduction of the quality of the metal are not achieved.

When these materials are loaded more than 20 minutes before the metal is introduced, the probability of its secondary oxidation by oxygen from the furnace atmosphere increases, which leads to additional consumption of ferroalloys.

The consumption of the mixture and the ratio in it of the main components are their, their (abrasive production waste and E1Sh slag) are interconnected and largely depend on the state of the bath at the end of finishing. However, in any conditions, with the consumption of abrasive waste less than 2 kg / ton of steel (Table 2)

2113002

as a result of insufficient desaturation, the goal is not achieved. The consumption of abrasive production wastes of 2 kg / ton of steel is 5 critical, starting from which the deoxidation capacity of the specified material increases dramatically and, due to a significant decrease in slag oxidation, favorable conditions are created for desulfurization of the metal.

With an increase in the consumption of the proposed deoxidizer of more than 2 kg / t of steel, these changes accumulate 15 s and at the consumption of 6 kg / t of steel reach the greatest values. A consumption of 6 kg / ton of steel is optimal for achieving the goal, as it provides the highest savings of ferroalloys with the maximum degree of desulfurization of the metal. A further increase in consumption of the proposed deoxidizer is accompanied by some deterioration.

25 conditions of sulfur mass transfer. This is due to the resulting slag heterogeneity and lowering of its temperature as a result of the endothermic reactions of its slag deoxidation with carbon and silicon carbide. The sulfur mass transfer coefficient and the degree of desulfurization of the metal decrease, despite the lower content of FeO in the slag. Reducing the consumption of ferroalloys and

35, the improvement of the quality of the metal according to the proposed method is ensured only by simultaneous input of abrasive production with waste (2-10 kg of steel) 1-6 kg / t of steel slag

40 eish, and the ratio of these materials can vary from 1: I to 2: 1. This ratio of components ensures the achievement of the goal regardless of the absolute value of their expenses. Slag ESR contains 30 - 65 CaF ,; 20-40% 0.2 - 2% FeO, less than 6X silica. The material is lumpy, the size of the pieces can reach 300 mm and is obtained during the development of the ANF-6 flux of electroslag remelting. The presence of EPI in the slag composition of highly liquefying components (and CaF) contributes to the increase of liquid mobility.

55 pshaka in the period of preliminary deoxidation and a decrease in its interfacial tension, which together with a low content of iron oxides is 3

gives favorable conditions for removing sulfur from metal in pshak. During the period under consideration, the degree of desulfurization of the metal is 1.5–2 times higher than the baseline melting using 25% ferrosilicon to remove the redox. Compared to the prototype type, the improvement in the quality of the metal according to the proposed method is achieved by simultaneously reducing the oxidation and viscosity of the slag, which significantly increases the distribution coefficient of sulfur between the slag and the metal,

 As follows from the data presented in Table 2, with a ratio of abrasive production and slag ESR 1: 1, the reduction in consumption of ferroalloys is not achieved, because, despite the high liquid mobility of the slag, the content of iron oxides in it is quite large and does not prevent the metal from oxidizing the period of its processing of these materials. The degree of desulfurization of the metal in the considered period of stabilization of the acidity is also small, which is associated with the thermodynamic conditions of the reaction: increase. the equilibrium concentration of sulfur in the metal with an increase in slag oxidation.

When the ratio of waste abrasive production and slag E11Sh more than 2: 1, the goal is not achieved. Excessive reduction of slag oxidation, its heterogeneity and exposure of individual metal areas are the reasons for the secondary oxidation of metal with gaseous oxygen and leads to higher levels of ferroalloys, JPe3KOe reduction of sulfur mass transfer coefficient in heterogeneous slag reduces the degree of desulfurization of the metal, which also contradicts the goal - better quality of sulfur.

0

The proposed method was tested under the conditions of the open-hearth shop, a 650-ton open-hearth furnace, working in the scrap process, with steel melting 3 sp for 15 min before the release of smelting to stabilize the oxidation of slag and metal injected abrasive production waste and slag ESR into amounts of 6 and 3 kg / t steel, respectively. During the period of holding the metal in the furnace, the oxidation of the bath was not observed. Deoxidation of the metal was carried out in ladles in accordance with: VII with technological instruction,

This sequence of actions is maintained when the abrasive production waste and ESR slag changes.

Table 3 shows the technology. The cus tic indicators of pilot industrial melts according to the proposed technology.

Table 4 presents the technological indicators of the experimental heats in comparison with the base variant,

As a base case, steel oxidization technologies were chosen in 650-ton open-hearth furnaces up to

implementation of the technology being developed. The technology of the base variant provides for the stabilization of slag and metal oxidation of 25% ferrosilicon,

As follows from the data presented, under the conditions of the open-hearth pro-. the proposed method of steel melting in an open-hearth furnace allows reducing the consumption of silicomanganese

by 0.9 kg / t of steel while simultaneously lowering the quality of the metal by increasing the degree of desulfurization of the metal during the stabilization period of the oxidation of pshak by 2 times. The use of secondary relatively cheap materials instead of scarce ferroalloys reduces the cost of steel and improves its quality.

The rate of oxidation of carbon. At the end of refining,% / h

Carbon content,% at the end of finishing

at the end of the stabilization period

Sulfur content,% at the end of refining

at the end of the stabilization period

Oxidation shpak (FeO),%

at the end of tweaking

at the end of the stabilization period

Consumption, ferroalloys in ladles, kg / t steel

Silica manganese

 Ferrosilicon (45%)

Atyumin

0.26 0.26 0.26 0.28 0.27

0.16 0.16 0.17 0.15 0.16

 0.15 0.17 0.15 0.12

0.048 0.046 0.048 0.045 0.046

0.048 0.046 0.047 0.044 0.046

6.4

7.4

5.2 0.9

6.0 6.4 6.0 6.2

5.2 3.2

6,6

3.2

6,6

4.9 4.6 0.9 0.9

2.62,0

6,47,2

4.75.0 0.90.9

Note, The consumption of waste abrasive production entered

in the furnace to stabilize the oxidation of the metal and slag, is equal to 6 kg / t.

T a b l 0 c a 1

6.0 6.4 6.0 6.2

3.2

6,6

4.6 0.9

2.62,0

6,47,2

4.75.0 0.90.9

121130010

T-a b l and c a 3

The rate of oxidation of carbon at the end of refining,% / h 0.24 0.25 0.23 0.25 0.25

Consumption, kg / t of steel

abrasive waste

Slag EPT Carbon content,%

at the end before vodgka

at the end of the stabilization period

Sulfur content,% at the end of refining

at the end of the period

stabilization

Slag oxidation FeO,%

at the end of tweaking

at the end of the stabilization period

Consumption of ferroalloys in ladles, kg / t steel

Silikomarga-

nets7.2 6.6 6.6 6.6 7.2

Carbon oxidation rate

at the end of finishing,% / h

Furnace consumption to stabilize oxidation, kg / t steel

Ferrosilicon Waste from the production of ferrosilicon Abrasive production waste

Ilak ESR

Consumption of ferroalloys in ladles, kg / t steel

T a- b l and c a 4

0.27

5, A

Claims (1)

METHOD OF STEEL Smelting in the open-hearth furnace, including melting, lapping, stabilization of the metal and slag oxidation 5–20 min before being released from the furnace and subsequent metal deoxidation in the ladle, characterized in that, in order to reduce the cost of ferroalloys and improve the quality of steel stabilization of the oxidation of metal and slag is carried out by abrasive waste containing 20-45% silicon carbide and 10-25% carbon, introduced into the furnace in the amount of 210 kg / t of steel simultaneously with electroslag slag in the amount of 1-6 kg / t ratio of these materials in the range of (1: 1) - (2: 1).