Bottom blowing air brick for ladle refining and refining method adopting bottom blowing air brick

Abstract

The invention relates to the technical field of ferrous metallurgy, in particular to a bottom blowing air brick for ladle refining and a refining method adopting the bottom blowing air brick, round hole gas channels are arranged in rows and are regularly distributed with slit gas channels, the bottom blowing air brick is easy to machine, materials are saved, argon has different bubble forms after entering molten steel through the bottom blowing air brick, and the molten steel is refined through the bottom blowing air brick. The method has the advantages of simple process, low cost and low possibility of gathering, improves the utilization efficiency of bottom blowing gas, enhances the stirring effect on molten steel, is favorable for removing inclusions with various particle sizes, and uniformizes the temperature and components, so that some steel types with high requirements on inclusion control and element content can be better produced, and the refining efficiency is improved. And the arrangement mode of the bottom blowing air bricks in the steel ladle is more beneficial to air flow stabilization, scouring to the ladle wall can be reduced, and the service life of the steel ladle is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a bottom-blown air-permeable brick used for ladle refining and a refining method using the same. Background Art

[0002] Blowing argon from the bottom of the ladle can even out the temperature and composition of the molten steel and promote the floating of inclusions. It is an effective means of refining molten steel. The effect of argon blowing directly affects the effect of ladle refining and the subsequent production rhythm. It is an important part of the entire steelmaking process. The type, quantity and relative position of the air bricks determine the distribution of the flow field in the ladle and the utilization rate of the stirring energy, which are important factors affecting the effect of argon blowing. According to the specific equipment conditions and production processes of the steel plant, designing and optimizing the argon blowing parameters of the ladle can improve the heat and mass transfer in the ladle, promote the slag interface reaction, and effectively improve the purification effect of the molten steel.

[0003] The main type of air-permeable bricks used in production now are dispersed air-permeable bricks, which can remove inclusions well and have good anti-permeability performance. The number of bubbles generated during use is large and uniform, which has a good refining effect. At the same time, it avoids the step of oxygen blowing and cleaning after each furnace smelting is completed, and the performance is effectively improved. There are two types of air-permeable bricks used in production, namely slit air-permeable bricks and straight-through directional air-permeable bricks, but they do not have these advantages of dispersed air-permeable bricks, so the amount of use is not large. However, there are also some inevitable problems when using dispersed air-permeable bricks, such as the difficulty of pore control, strong bubble aggregation, poor air flow stability, low brick strength, etc., which greatly reduce the service life of air-permeable bricks. Moreover, the removal of inclusions during argon blowing is closely related to the size of bubbles in the molten steel, and bubbles of different sizes have different capture rates for inclusions of the same particle size. At the same time, the air-permeable bricks currently used have only one ventilation pipe at the bottom, and only one gas can be introduced at a time. If other gases are introduced into the ladle at the same time, additional devices need to be set up, which increases the production cost. Summary of the invention

[0004] The main purpose of the present invention is to provide a bottom-blown air-permeable brick for ladle refining and a refining method using the same, aiming to solve the problems existing in the bottom-blown air-permeable brick in the prior art.

[0005] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0006] A bottom-blowing air-permeable brick for ladle refining, comprising an air-permeable brick body, a gas channel and an air inlet pipe;

[0007] The air-permeable brick body is in a truncated cone shape, and a gas passage is provided between the top and bottom surfaces of the air-permeable brick body and runs through the body in a vertical direction as a whole, and the air inlet pipe is connected to the gas passage opening on the bottom surface of the air-permeable brick body;

[0008] The gas passages include slit gas passages and circular hole gas passages, which are respectively distributed on two semicircular platforms of the air-permeable brick body.

[0009] As a preferred embodiment of a bottom-blown air-permeable brick for ladle refining described in the present invention, the longitudinal cross-section of the slit gas channel along the length direction is an isosceles trapezoid, and the inner angle between the side and the short side of the isosceles trapezoid is 91°-93°; the longitudinal cross-section of the slit gas channel along the width direction is a rectangle; the width of the slit is 1.6-2.0 mm, the length of the slit on the top surface of the air-permeable brick body is 38-40% of the radius of the top surface of the air-permeable brick body, and is located in the middle of the radius; the number of the slit gas channels is 15-18, and the slit gas channels are evenly distributed on a semicircular platform on one side of the air-permeable brick body along the radial direction.

[0010] As a preferred embodiment of a bottom-blown air-permeable brick for ladle refining described in the present invention, the circular hole gas channel is generally in a hollow truncated cone structure with a larger upper portion and a smaller lower portion, and the angle between the side of the circular hole gas channel and the vertical direction is 1°-3°; the diameter of the circular hole on the top surface of the air-permeable brick body is 1.6-2.0 mm; n circular hole gas channels are arranged in a row, n≥2, and the distance between the centers of the two circular holes at both ends of each row on the top surface of the air-permeable brick body is 36-38% of the radius of the top surface of the air-permeable brick body, and is located in the middle of the radius; 15-18 rows of circular hole gas channels are arranged, and each row of circular hole gas channels is evenly distributed on a semi-circular cone on one side of the air-permeable brick body along the radial direction.

[0011] As a preferred embodiment of the bottom-blown air-permeable brick for ladle refining described in the present invention, the bottom radius of the air-permeable brick body is 1.6-2 times the top radius; and the height of the air-permeable brick body is 460-480 mm.

[0012] As a preferred solution of the bottom-blown air-permeable brick used for ladle refining described in the present invention, the number of the slit gas channels is equal to the number of columns of the circular hole gas channels.

[0013] As a preferred embodiment of the bottom-blown air-permeable bricks for ladle refining described in the present invention, each slit gas channel and circular hole gas channel is independently connected to an air inlet pipe at the lower end, and the air inlet pipes of the slit gas channel and the air inlet pipes of the circular hole gas channel are respectively integrated into a ventilation pipe, presenting an umbrella rib shape.

[0014] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution:

[0015] A ladle refining method comprises the following steps:

[0016] S1. Install the above-mentioned bottom blowing air bricks at the bottom of the ladle;

[0017] S2. Different types of gases are blown into the molten steel through bottom blowing air bricks to achieve ladle refining.

[0018] As a preferred embodiment of the ladle refining method described in the present invention, in step S1, two bottom blowing air bricks are installed at the bottom of the ladle, and the center angle between the two bottom blowing air bricks is 135°. One of the bottom blowing air bricks is 0.3R away from the center of the bottom of the ladle, and the other bottom blowing air brick is 0.5R away from the center of the bottom of the ladle, and R is the radius of the bottom of the ladle.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention provides a bottom-blown air-permeable brick for ladle refining and a refining method using the same. The circular hole gas channels are arranged in a row and regularly distributed with the slit gas channels. The processing is simple and material-saving. After the argon enters the molten steel through the bottom-blown air-permeable brick, it has different bubble forms and is not easy to aggregate. The utilization efficiency of the bottom-blown gas is improved, the stirring effect on the molten steel is enhanced, and it is beneficial to remove inclusions of various particle sizes, uniform temperature and composition, so that some steel types with high requirements for inclusion control and element content can be better produced, and the refining efficiency is improved. In addition, the arrangement of the bottom-blown air-permeable bricks in the ladle of the present invention can change the gas type and gas volume corresponding to each channel, which is more conducive to the stability of the gas flow, can reduce the scouring of the ladle wall, and improve the service life of the ladle. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 It is a top view of the bottom-blown air-permeable brick of the present invention.

[0023] Figure 2 It is a schematic diagram of the structure of the bottom-blown air-permeable brick of the present invention.

[0024] Figure 3 This is a comparison chart of the mixing time of the bottom-blown air-permeable brick and the dispersive air-permeable brick of the present invention.

[0025] Figure 4 This is a comparison chart of the inclusion removal rates of the bottom-blown air-permeable brick and the dispersive air-permeable brick of the present invention.

[0026] Figure 5 This is a comparison diagram of bubbles generated by the bottom-blown air-permeable brick and the diffuse air-permeable brick of the present invention.

[0027] Among them, 1-slit, 2-circular hole, 3-slit gas channel, 4-circular hole gas channel, 5-air permeable brick body, 6-ventilation duct, 7-umbrella rib shape.

[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] According to one aspect of the present invention, the present invention provides the following technical solution:

[0031] like Figure 1-2 As shown, a bottom-blowing air-permeable brick for ladle refining comprises an air-permeable brick body 5, a gas channel and an air inlet pipe;

[0032] The air-permeable brick body 5 is truncated cone-shaped, and a gas passage is provided between the top and bottom surfaces of the air-permeable brick body 5 and runs vertically through the body, and the air inlet pipe is connected to the gas passage opening on the bottom surface of the air-permeable brick body 5;

[0033] The gas passage comprises a slit gas passage 3 and a circular hole gas passage 4, which are respectively distributed on two semicircular platforms of the air-permeable brick body 5.

[0034] Preferably, the longitudinal cross-section of the slit gas channel 3 along the length direction is an isosceles trapezoid, and the inner angle between the side and the short side of the isosceles trapezoid is 91°-93°; the longitudinal cross-section of the slit gas channel 3 along the width direction is rectangular; the width of the slit 1 is 1.6-2.0 mm, and the length of the slit on the top surface of the air-permeable brick body 5 is 38-40% of the radius of the top surface of the air-permeable brick body 5, and is located in the middle of the radius; the number of slit gas channels 3 is 15-18, and the slit gas channels 3 are evenly distributed on a semicircular platform on one side of the air-permeable brick body 5 along the radial direction.

[0035] Preferably, the circular hole gas channel 4 as a whole has a hollow truncated cone structure that is larger at the top and smaller at the bottom, and the angle between the side of the circular hole gas channel 4 and the vertical direction is 1°-3°; the diameter of the circular hole 2 on the top surface of the air-permeable brick body 5 is 1.6-2.0 mm; n circular hole gas channels 4 are in a row, n≥2, and the distance between the centers of the two circular holes 2 at both ends of each row on the top surface of the air-permeable brick body 5 is 36-38% of the radius of the top surface of the air-permeable brick body 5, and is located in the middle of the radius; 15-18 rows of circular hole gas channels 4 are arranged, and each row of circular hole gas channels 4 is evenly distributed on a semi-circular cone on one side of the air-permeable brick body 5 along the radial direction.

[0036] Preferably, the bottom radius of the air-permeable brick body 5 is 1.6-2 times the top radius; the height of the air-permeable brick body 5 is 460-480 mm.

[0037] Preferably, the number of the slit gas channels 3 is equal to the number of columns of the circular hole gas channels 4 .

[0038] Preferably, each slit gas channel 3 and circular hole gas channel 4 is independently connected to an air inlet pipe at its lower end, and the air inlet pipes of the slit gas channel and the air inlet pipes of the circular hole gas channel are respectively integrated into a ventilation pipe 6, and the connection between the ventilation pipes is in an umbrella rib shape 7.

[0039] According to another aspect of the present invention, the present invention provides the following technical solution:

[0040] A ladle refining method comprises the following steps:

[0041] S1. Install the above-mentioned bottom blowing air bricks at the bottom of the ladle;

[0042] S2. Different types of gases are blown into the molten steel through bottom blowing air bricks to achieve ladle refining.

[0043] Preferably, in step S1, two bottom blowing air bricks are installed at the bottom of the ladle, and the center angle between the two bottom blowing air bricks is 135°. One of the bottom blowing air bricks is 0.3R away from the center of the bottom of the ladle, and the other bottom blowing air brick is 0.5R away from the center of the bottom of the ladle, where R is the radius of the bottom of the ladle.

[0044] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0045] The technical solution of the present invention was simulated by physical simulation. The bottom-blown air-permeable brick and the ladle were reduced in size according to a geometric similarity ratio of 1:4.4 based on the sizes of the bottom-blown air-permeable brick and the ladle used in actual production, and were made of plexiglass. The top surface of the bottom-blown air-permeable brick was half slit and half circular hole, wherein three circular holes were in a row, and the angle of each row was 12°, with a total of 15 slits and 15 rows of circular holes. The bottom diameter of the air-permeable brick was 50 mm, and the top diameter was 31 mm. The longitudinal section of the slit gas channel along the length direction was an isosceles trapezoid, and the inner angle between the side and the short side of the isosceles trapezoid was 91°. The longitudinal section of the slit gas channel along the width direction was a rectangle. The length of each slit was 6 mm, the width was 0.4 mm, and it was located in the middle of the radius. The slit gas channels were evenly distributed on a semicircular platform on one side of the air-permeable brick body along the radial direction. The circular hole gas channel is a hollow truncated cone structure with a large top and a small bottom. The angle between the side of the circular hole gas channel and the vertical direction is 1°; the diameter of each circular hole on the top surface of the air-permeable brick body is 0.4mm; the distance between the centers of the two circular holes at both ends of each column of the top surface of the air-permeable brick body is 5.6mm, and is located in the middle of the radius; each column of circular hole gas channels is evenly distributed on a semi-circular cone on one side of the air-permeable brick body along the radial direction. The height of the air-permeable brick body 5 is set to 105mm. Each slit gas channel and the lower end of the circular hole gas channel are independently connected to an air inlet pipe, and the air inlet pipes of the slit gas channel and the air inlet pipes of the circular hole gas channel are respectively collected in one pipe, presenting an umbrella rib shape.

[0046] Two bottom-blowing air-permeable bricks are installed at the bottom of the ladle. The center angle between the two bottom-blowing air-permeable bricks is 135°. The distance between one bottom-blowing air-permeable brick and the center of the bottom of the ladle is 0.3R, and the distance between the other bottom-blowing air-permeable brick and the center of the bottom of the ladle is 0.5R. R is the radius of the bottom of the ladle. The bottom diameter of the ladle is 650mm, the top diameter of the ladle is 760mm, and the height is 900mm.

[0047] The bottom blowing flow rate calculation process according to similarity theory is:

[0048]

[0049] Fr m ′=Fr p ′ (2)

[0050]

[0051]

[0052]

[0053]

[0054] Where Fr′ is the modified Froude number, dm The diameter of the air brick used in the model is 31mm, d p The diameter of the air brick used in the production site is 140mm, H m is the liquid level height of the ladle model, 602mm, H p On-site ladle molten pool depth, 2650mm, T m is room temperature, 298K, T p is the temperature of the molten steel, 1873K, P atm Standard atmospheric pressure, 1.0313×10 5 pa,ρ l，p is the density of molten steel under standard conditions, 7000kg / m 3 ρ l，m The density of water under standard conditions is 1000kg / m 3 ρ g，p is the density of argon under standard conditions, 1.784 kg / m 3 ρ g，m The density of air under standard conditions is 1.29kg / m 3 ; g is a constant, 9.8m / s 2 , Q m is the air flow rate of the model air brick, Q p Q is the air flow rate of the on-site ventilation bricks, A is the flow meter indication value, Q real is the high temperature gas flow rate.

[0055] The relationship between the model and prototype inlet gas volume is shown in equations (9)-(10):

[0056] Q m =0.01576Q real (7)

[0057] Q A =0.0185Q real (8)

[0058] Under the condition of 300L / min at the production site, the bottom blowing volume in the water simulation experiment is calculated to be 5.6L / min. Turn on the air pump and adjust the flow meter to 5.6L / min. The bottom of the ladle is a double-permeable brick. Each permeable brick has two ventilation pipes, a total of four. The ventilation volume of each pipe is 1.4L / min, and the gas type is air. After the flow field in the ladle model is stable, add KCl to measure the mixing time ( Figure 3 ), and observe the bubble morphology of different bottom-blown air-permeable bricks ( Figure 5 ), and numerical simulation was used to simulate the inclusion removal ( Figure 4 ).

[0059] Figure 3This is a comparison chart of the mixing time of the bottom-blowing air brick and the dispersed air brick of the present invention. It can be seen that the mixing time of the bottom-blowing air brick of the present invention is 12s faster than that of the dispersed air brick. Figure 4 This is a comparison chart of the inclusion removal rates of the bottom-blown air bricks and the dispersed air bricks of the present invention. It can be seen that under different particle sizes, the removal effect of the bottom-blown air bricks of the present invention is better than that of the dispersed air bricks, among which the removal rate of 5μm is increased by 2.4%, the removal rate of 20μm is increased by 3.3%, and the removal rate of 100μm is increased by 2.5%. Figure 5 The bottom-blown air-permeable brick of the present invention ( Figure 5 Middle left) and diffuse air brick ( Figure 5 From the comparison diagram of the bubbles produced by the bottom-blown air brick of the present invention, it can be clearly seen that when the bottom-blown air brick of the present invention is used, the bubbles are more dispersed, the airflow is more stable, and bubbles of different shapes are produced at the same time, while the bubbles produced by the dispersed air brick are of a single shape, with a high degree of aggregation, and the airflow has a certain degree of deviation.

[0060] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A bottom-blown air-permeable brick for ladle refining, characterized in that: It includes a breathable brick body, a gas channel and an air inlet pipe; The air-permeable brick body is in a truncated cone shape, and a gas passage is provided between the top and bottom surfaces of the air-permeable brick body and runs through the body in a vertical direction as a whole, and the air inlet pipe is connected to the gas passage opening on the bottom surface of the air-permeable brick body; The gas passages include slit gas passages and circular hole gas passages, which are respectively distributed on two semicircular platforms of the air-permeable brick body.

2. The bottom-blown air-permeable brick for ladle refining according to claim 1, characterized in that: The longitudinal cross section of the slit gas channel along the length direction is an isosceles trapezoid, and the longitudinal cross section of the slit gas channel along the width direction is a rectangle; the slit is located in the middle of the radius.

3. The bottom-blown air-permeable brick for ladle refining according to claim 2, characterized in that: The inner angle between the side and the short side of the isosceles trapezoid is 91°-93°, the width of the slit is 1.6-2.0 mm, and the length of the slit on the top surface of the air-permeable brick body is 38-40% of the radius of the top surface of the air-permeable brick body; the number of slit gas channels is 15-18, and the slit gas channels are evenly distributed on a semicircular platform on one side of the air-permeable brick body along the radial direction.

4. The bottom-blowing air-permeable brick for ladle refining according to claim 1, characterized in that: The circular hole gas channel is generally in a hollow truncated cone structure that is larger at the top and smaller at the bottom. The n circular hole gas channels are arranged in a row, n≥2, and are generally located in the middle of the radius.

5. The bottom-blowing air-permeable brick for ladle refining according to claim 4, characterized in that: The angle between the side of the circular hole gas channel and the vertical direction is 1°-3°; the diameter of the circular hole on the top surface of the air permeable brick body is 1.6-2.0mm; the distance between the centers of the two circular holes at both ends of each column on the top surface of the air permeable brick body is 36-38% of the radius of the top surface of the air permeable brick body; 15-18 columns of circular hole gas channels are arranged, and each column of circular hole gas channels is evenly distributed on a semicircular platform on one side of the air permeable brick body along the radial direction.

6. The bottom blowing air brick for ladle refining according to claim 1, characterized in that: The bottom radius of the air brick body is 1.6-2 times the top radius; the height of the air brick body is 460-480mm.

7. The bottom-blowing air-permeable brick for ladle refining according to claim 1, characterized in that: The number of the slit gas channels is equal to the number of the round hole gas channels; the lower end of each slit gas channel and the round hole gas channel is independently connected to an air inlet pipe.

8. A ladle refining method, characterized in that: The steps include: S1. Install the bottom-blowing air-permeable brick according to any one of claims 1 to 7 at the bottom of the ladle; S2. Different types of gases are blown into the molten steel through bottom blowing air bricks to achieve ladle refining.

9. The ladle refining method according to claim 8, characterized in that: In step S1, two bottom blowing air bricks are installed at the bottom of the ladle, and the center angle between the two bottom blowing air bricks is 135°. The distance between one bottom blowing air brick and the center of the bottom of the ladle is 0.3R, and the distance between the other bottom blowing air brick and the center of the bottom of the ladle is 0.5R, where R is the radius of the bottom of the ladle.

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