SU1357434A1 - Method of working liquid steel - Google Patents

Abstract

This invention relates to ferrous metallurgy, in particular, to the technology of treating liquid steel in a ladle with neutral gases and powdered materials when it is extruded from a steelmaking unit. The purpose of the invention is to increase the efficiency of the use of gas blowing and powder material. The method of treating liquid steel involves the release of steel through a chute into a ladle, additive additives and the supply of gas and powdered materials through a purge tuyere immersed in metal. In the process of blowing metal tuyere placed in terms of the bucket in the central; zone, with a central angle of 135-225, a central area with a radius of 0.1-0.3 and 0.7-0.75 of the bottom of the bucket radius, and shifted to the opposite part of the trench from the bucket. The depth of immersion of the tuyere during purging varies from 20 to 10% of the height of the metal level in the ladle. The invention allows to significantly increase the processing efficiency of steel with powdered materials and to improve its quality. 1 hp f-ly, 3 ill., 4 tab. i (L S to SP i oo 4

Description

The invention relates to ferrous metallurgy, in particular, to the technology of treating liquid steel in a ladle with neutral gases and powder-like materials when it is taken from a steelmaking unit.

The purpose of the invention is to increase the efficiency of using gas blowing and a nozzle-like material.

The schematic representation shows the relative position of the purge tuyere in terms of the bucket and the axis of the gutter that supplies liquid steel; figure 2 - graphic data of the test results of the proposed method of purging; on FIG. 3 - the same as in FIG., with indication of the optimal parameters of the method.

The proposed arrangement of the tuyere provides the maximum residence time and the amount of solid 1X particles in the volume of the metal being processed.

I

Studies have shown that 5 at various points in the bucket volume, metal flows have not only different speeds, but also different directions. The choice of the optimal entry point for the blowing lance relative to the center of the bucket is determined by the kinetic energy of the falling metal jet and the powder and gas flow at the nozzle exit. Based on the results of studies performed under laboratory conditions, the highest values of the ratio of the mass of powder remaining in the fluid volume (t,) during the test time, to the total mass of the injected

powder (t

and consequently.

the residence time of the dispersed particles in the liquid takes place when the tuyere is located in the proposed site. Visual observations of the development of circulating fluid flows on the transparent model of the bucket also show that the most favorable hydrodynamic conditions are developing in this area to increase the residence time of dispersed particles in the bulk of the metal.

When the tuyere is immersed beyond the limits of 1-4 and the proposed site (excluding part of the sector outside the radius R), the tuyere falls into the backflow zone of the metal arising from the impact of a flowing stream of metal and

574342

The processing power of powdered materials decreases dramatically (Table 1).

The immersion of the tuyere within the sector, limited to an angle of 90 °, but

5 The limits of the arc with a radius of 75% of the bottom of the bucket, i.e. in the immediate vicinity of the lining, leads to local wear of the lining of the ladle, which is unacceptable with

fO point of view of bucket durability. The depth of immersion of the tuyere in the metal is determined on the basis of data on the injection of powdered material into a 50-ton teeming ladle,

5 At the beginning of the purge, when the ladle is filled at 1/4 of the height, the immersion of the tuyere at depths of less than 20% of the height of the metal column is characterized by low absorption of the blown material into the metal.

20 Increasing the immersion depth of the tuyere by more than 50% of the height of the metal column leads to wear of the lining (Table 2).

25 At the end of the purge, the immersion of the tuyere less than 10% of the height of the metal column leads to an abbreviation of the duration of the stay: powder as a material in the metal volume and reduced the efficiency of metal processing with the powder When the tuyere is immersed to a depth of more than 30 meters. 25% of the height of the metal column mvic-eT is the place of intense wave formation: it is not on the metal surface, which is HFYBIT for metal losses and the output of a short-haul steel-breaking bucket (Table 3),

Testing under the production conditions of the proposed method under 40 confirmed the effectiveness of its use in the processing of metal with powdered materials.

The proposed includes operations performed; in the following 45 degrees:; eq metal from the steelmaking unit into the ladle; priming of deoxidizers or leggate materials after) - bucket fillings to one third of the height; one-time supply of neutral gases with powdered materials through the tuyere, which is located in the proposed site

With this arrangement, the blowing lance of the tuyere is purging until the slag appears in the bucket, after which the tuyere is removed from the bucket 1 and the supply of neutral gases and powdery materials of the Sh1X is stopped.

55

Example. Low alloyed steel is smelted in a 100-ton open-hearth furnace and released into a ladle, where the metal is simultaneously treated with neutral gas and powdered lime. The mass injection rate of lime 300 kg / min, a concentration of 40 kg / m. Nitrogen ({0.035 - 0.040)% is used as a neutral gas.

The tuyere is lowered into the metal and the purge starts when the bucket is filled 1/4 of its height.

During purging, the tuyere is located in the coordinates of FIG. The metal blowing is completed when slag appears in the ladle. The consumption of powdered lime was 1% by weight of the metal, Tables 1–3 are presented in accordance with FIGS. 1 and 3) options for treating molten steel in a ladle with powdered material; Data on the effect of the location of the blowing tuyeres on their durability are given in Table 4.

The data in Table 1 shows that when neutral gas and powdered material are supplied during metal injection through the tuyere located at the proposed site, the sulfur content in the metal is reduced by 0.005-0.008% compared to other corners. .

According to the curves in FIG. 3, the highest values are {nin n) 100% J, and, consequently, the residence times of dispersed particles in the liquid.

Q

5 o 5,

about with

0

take place at the location of the tuyere in the sector cf 135 - 225, limited by arcs with radii of 0.2R and 0.75R. The experimental data obtained confirm that the point of entry of the blowing tuyere significantly affects the residence time of dispersed particles in the volume of the metal being processed and, consequently, the degree of completion of mass transfer processes during the interaction of the liquid metal with blown powdered materials.

Thus, the use of the proposed method allows to significantly increase the efficiency of steel processing with powdered materials and improve its quality.

Claims (2)

1. A method of treating molten steel, including discharging steel through a chute into a ladle, adding additives and supplying gas and powdered materials through a metal blowing lance immersed in metal, characterized in that, in order to increase the efficiency of using gas blowing and powdered material, during purging the metal the tuyere is placed in terms of the bucket in the central zone bounded by a sector with an angle of 135-225, a circle with a radius of 0.1-0.3 and O ,, 7-0.75 of the radius of the bottom of the bucket and located in the part of the bucket opposite to the groove. 2. Method POP.1, characterized in that the depth of the tuyere during purging varies from 20 to 10% of the height of the metal level in the ladle. Consumption of powdered material, t The amount of sulfur removed from the metal,% Carrying out the powder with a carrier gas of metal,% of the mass of the injected powder Reduced bucket durability,% The presence of splash metal bucket The amount of sulfur removed from the metal,% Table 1.0 1.0 1.0 1.0 1.0 0,007 0,012 0,015 0,0120,007 401512 OO OO Table 3 No No No No Yes 0,007 0,010 0,012 0,015 0,016 " powder input into the metal along the radius corresponding to the angle O was made by a lance only at a radius of 0.2 R. No entry is possible at radii 0.5R and 0.8R because of the falling jet of metal; Further experiments along the arc of a given radius were discontinued due to the occurrence of a large breaker at the bucket wall, which led to local wear of the lining. Table 4 Cma e6bint / cf ((same / tfff J / 5 22S 4 Sta / geraz / gi 6ot Hb / U Kffsuf y ctcmoff Exposure epypftibi f35 " I yes n / t; J -§. Iq ten about 50 60 90/20 150 t h, hail. (rig 2 2 Editor N.Egorova Compiled by A.Minaev Tehred M.Didzh Order 5968/23 Circulation 550 Subscription VNIIPI USSR State Committee on affairs of inventions and openings 113035, Moscow, Zh-35, Raushsk nab., d. 4/5 Production and printing company, Uzhgorod, Projecto st., 4 Proofreader A.T. sko