CN102151811A - Method for capturing continuous casting inclusion and novel submersed nozzle - Google Patents

Abstract

The invention relates to the fields of metal solidification and continuous casting, in particular to a method for capturing inclusions in continuous casting and a novel submerged nozzle. The new submerged nozzle (1) with the function of capturing inclusions in continuous casting is composed of upper and lower parts: the upper part of the nozzle (2) has a nozzle side outlet hole (5), which has the function of conventional molten steel diversion; the upper part of the nozzle (2) Adding a closely connected nozzle lower part (3), the nozzle lower part (3) has the function of capturing inclusions, so that the inclusions in the rotating molten steel are captured by the nozzle lower part (3) and gathered on the outer surface (9) of the nozzle lower part (3) ) to effectively remove inclusions from molten steel. The novel submerged nozzle of the invention has a long service life, can effectively remove inclusions in molten steel, improve the quality of casting slabs, and prolong the service life of the crystallizer.

Description

A method of capturing inclusions in continuous casting and its new submerged nozzle

technical field

The invention relates to the fields of metal solidification and continuous casting, in particular to a method for capturing inclusions in continuous casting and a novel submerged nozzle.

Background technique

With the continuous progress of metallurgical technology, the development of the national economy has higher and higher requirements for high strength, high toughness and service life of steel products. In particular, automobiles, high-speed trains, cable bridges, etc. have increased requirements on the fatigue life of steel, and the control of inclusions in steel has become more and more stringent. The total amount of inclusions in steel (usually expressed by total oxygen content) has changed from the past Dozens of ppm and dozens of ppm are reduced to several ppm, and the service life and safety performance of steel are improved.

At present, in the iron and steel production process, the removal of inclusions mainly depends on ladle refining, such as argon blowing and stirring in ladles, LF refining furnaces, vacuum refining furnaces, etc. to effectively remove deoxidized products and inclusions in steel. In the subsequent process of molten steel from the ladle to the tundish, it is generally a process of increasing pollution, so a reasonable tundish design is also an important aspect of removing inclusions. After the molten steel enters the crystallizer, effectively removing the inclusions in the molten steel in the mold is the last link to reduce the total amount of inclusions in the steel. In the existing technology, the removal of inclusions in the molten steel in the crystallizer is generally accomplished by optimizing the design of the submerged nozzle. The optimized design of the submerged nozzle can effectively promote the floating of inclusions in molten steel, and be absorbed and removed by the mold slag covering the surface of molten steel.

Chinese utility model patent ZL03211455.9 (publication number CN2607214Y) discloses a 'continuous casting crystallizer submerged nozzle', which is a porous submerged nozzle for continuous casting blooms, and its purpose is to design nozzle side outlet holes with different shapes and angles , in order to slow down the kinetic energy of the nozzle injection flow and the impact of the injection flow on the mold wall, while increasing the service life of the mold, reduce the disturbance to the liquid steel level in the mold, stabilize the flow field in the mold, and effectively promote the removal of inclusions float up.

Chinese appearance design patent ZL03351513.1 (publication number CN3383817) then provides a kind of appearance design of ' submerged nozzle '. The design and function of the above two submerged nozzles are the same as the submerged nozzles commonly used in metallurgical enterprises at present. Generally, the shape design of the submerged nozzle and the outlet hole on the side of the nozzle can achieve the introduction of molten steel, reduce the disturbance of the liquid surface, and promote the floating of inclusions. and other effects. Therefore, the bottom of this type of nozzle is generally flat, and the distance from the bottom of the nozzle to the bottom of the outlet hole on the side of the nozzle is relatively short, generally 30-60mm. The shorter nozzle bottom design is only for structure and support.

In existing submerged nozzle devices, insufficient or no consideration has been given to the submerged nozzle's ability to adhere and remove inclusions.

Contents of the invention

The purpose of the present invention is to provide a method for capturing inclusions in continuous casting and a new submerged nozzle thereof. To achieve the above object, the present invention provides the following technical solutions:

The first aspect of the present invention is to provide a method for capturing inclusions in continuous casting: using a novel submerged nozzle (1) with the function of capturing inclusions in continuous casting, the submerged nozzle is composed of upper and lower parts: the upper part of the nozzle (2) There is a nozzle side outlet hole (5), which has the function of conventional molten steel diversion; a closely connected nozzle lower part (3) is added to the upper part of the nozzle (2), and the lower part of the nozzle (3) has the function of capturing inclusions, so that the rotating steel The inclusions in the water are captured by the lower part of the nozzle (3) and gathered on the outer surface (9) of the lower part of the nozzle (3), thereby effectively removing the inclusions from the molten steel.

In the submerged nozzle, L/h=2.5-15, where h is the distance from the lower edge of the outlet hole (5) on the side of the nozzle to the lower edge (7) of the upper part of the nozzle (2), and L is the lower edge of the upper part of the nozzle (2) (7) The length to the lower end of the lower part of the nozzle (3).

The outer surface of the lower part (3) of the nozzle is coated with a coating containing calcium oxide, which is used to adsorb aluminum oxide and silicon oxide inclusions in molten steel to form composite inclusions of calcium oxide and aluminum oxide, calcium oxide and silicon oxide.

The calcium oxide-containing coating has a thickness of 1-3 mm and is made of calcium oxide, or calcium oxide plus magnesium oxide, or calcium oxide plus silicon oxide.

The second aspect of the present invention is to provide a new submerged nozzle (1) with the function of capturing inclusions in continuous casting. Conventional molten steel diversion function; the upper part of the nozzle (2) is added with a closely connected lower part of the nozzle (3), and the lower part of the nozzle (3) has the function of capturing inclusions, so that the inclusions in the rotating molten steel are captured and gathered by the lower part of the nozzle (3) The outer surface (9) of the nozzle lower part (3) plays the role of effectively removing inclusions from molten steel.

In the submerged nozzle, L/h=2.5-15, where h is the distance from the lower edge of the outlet hole (5) on the side of the nozzle to the lower edge 7 of the upper part of the nozzle (2), and L is the lower edge (7) of the upper part of the nozzle (2). ) to the lower end of the nozzle lower part (3).

The upper part of the nozzle (2) and the lower part of the nozzle (3) are an integral type or a combined type in which the two are connected; the materials of the two are the same or different.

The connection between the upper part of the nozzle (2) and the lower part of the nozzle (3) is a fixed connection or a detachable connection.

The lower part of the nozzle (3) is the same columnar shape as the upper part of the nozzle (2) or a platform with a large top and a small bottom.

The bottom of the nozzle lower part (3) is a concave hollow structure (8).

The outer surface (9) of the nozzle lower part (3) is smooth or has a raised block or groove.

When in use, the depth of the submerged nozzle (1) inserted into the molten steel is to keep the distance H from the upper edge of the molten steel side outlet hole (5) of the nozzle to the molten steel surface (6) to be 50-150mm, and L to be 50-300mm, h is 20-80mm.

There are two or more nozzle side outlet holes (5) in the upper part (2) of the nozzle; in the direction of looking down, the center line of the nozzle side outlet hole (5) and the center line of the nozzle form an angle of 0-35°. Angle α; In the vertical direction, the center line of the nozzle side outlet hole (5) and the horizontal line form an included angle β of 0-30°.

The material of the upper part (2) of the nozzle is one of aluminum-carbon, aluminum-zirconium-carbon, magnesium-carbon, aluminum-calcium and fused silica.

The material of the nozzle lower part (3) is zirconia, calcium oxide, magnesium oxide, aluminum oxide, silicon oxide, etc., or a combination of two or more thereof.

Coat the outer surface of the lower part of the nozzle (3) with a thickness of 1-3mm and a coating made of calcium oxide, or calcium oxide plus magnesium oxide, or calcium oxide plus silicon oxide, for adsorption of aluminum oxide and silicon oxide in molten steel Inclusions form composite inclusions of calcium oxide and aluminum oxide, calcium oxide and silicon oxide.

In the part of the slag line that is in contact with steel and slag, an anti-corrosion ring made of zirconium and zirconium carbon is set outside the nozzle.

In the present invention, the reaction mechanism between the lower part of the nozzle 3 and the molten steel inclusions is that, because the inclusions in the molten steel in the crystallizer move to the center by the rotation of the molten steel on the horizontal section, the inclusions such as aluminum oxide and silicon oxide in the molten steel are very large. Easily adsorbed by basic oxides such as calcium oxide in the lower part of the nozzle 3. In actual industrial use, the position of the electromagnetic stirring of the mold is installed in the middle and lower part of the mold, that is, the fastest rotating area of molten steel is in the middle and lower part of the mold. The key of the present invention is to increase the length of the lower part of the nozzle, so that the submerged nozzle can be extended into the strong rotation area of the molten steel, which greatly increases the probability of collision between the inclusions in the molten steel and the surface of the submerged nozzle, and improves the quality of the submerged nozzle. The chance of capturing inclusions in molten steel; on the other hand, increasing the length of the lower part of the nozzle will also increase the probability of collision between inclusions in molten steel and the surface of the submerged nozzle, and improve the chance of capturing inclusions in molten steel by the submerged nozzle .

The distance from the lower edge of the side outlet hole (5) of the existing nozzle to the lower edge (7) of the upper part of the nozzle (2) is very short, generally only 20-80 mm, and the position of the side outlet hole of the nozzle is relatively fixed. It is unfavorable to extend the nozzle into the strong rotation area in the crystallizer and to improve the chance of capturing the inclusions in molten steel by the submerged nozzle.

Compared with the existing submerged nozzle, the advantages of the present invention are:

1. The length of the lower part of the submerged nozzle is extended, and in the effective area of electromagnetic stirring, the collision chance between the inclusions accumulated in the molten steel toward the center and the lower part of the nozzle is improved;

2. An inclusion capture device is installed to effectively remove inclusions in molten steel;

3. In the direction of looking down, the center line of the outlet hole on the nozzle side forms an angle α with the center line of the nozzle, which improves the effect of electromagnetic stirring;

4. In the vertical direction, the center line of the outlet hole on the side of the nozzle forms an angle β with the horizontal line, which improves the melting ability of molten steel on mold slag and prevents slag entrainment;

The submerged nozzle of the invention has a long service life, can effectively remove inclusions in molten steel, improve the quality of casting slabs, and prolong the service life of the crystallizer.

Description of drawings

Fig. 1 is a novel submerged nozzle with the function of capturing inclusions of the present invention;

Figure 2 is a new integral submerged nozzle with the same material;

The combined novel submerged nozzle of Fig. 3 different materials (pressing or casting forming);

The combined novel submerged nozzle (thread connection) of Fig. 4 different materials;

The lower part of the nozzle in Fig. 5 is columnar, with raised blocks on its surface;

The lower part of the platform-shaped nozzle in Fig. 6 has a groove-like surface;

Fig. 7 is a top view of the structure of outlet holes on the side of multiple nozzles.

reference sign

1 new submerged nozzle

2 the upper part of the nozzle

3 the lower part of the nozzle

4 crystallizer

5 nozzle side outlet hole

6 molten steel surface

7 The lower line 7 of the upper part 2 of the nozzle

8 The hollow structure at the bottom of the lower part 3 of the nozzle

9 The outer surface of the nozzle lower part 3

10 Connecting threads of the upper part 2 of the nozzle and the lower part 3 of the nozzle

The distance from the upper edge of the outlet hole 5 on the H nozzle side to the liquid steel surface 6

h The distance from the lower edge of the nozzle side outlet hole 5 to the lower edge 7 of the upper part of the nozzle 2, 20-80mm

αIn the direction of top view, the angle between the centerline of the outlet hole 5 on the nozzle side and the centerline of the nozzle

βIn the vertical direction, the angle between the center line of the nozzle side outlet hole 5 and the horizontal line

The length from the lower edge 7 of the upper part 2 of the L nozzle to the lower end of the lower part 3 of the nozzle is 50-300mm

Detailed ways

The present invention will be further described below according to accompanying drawing.

As shown in Figure 1, the novel submerged nozzle 1 with the function of capturing inclusions of the present invention is composed of upper and lower parts, the upper part 2 of the nozzle is a submerged nozzle with conventional functions; The protruding part is an inclusion trapping device; the upper part 2 of the nozzle and the lower part 3 of the nozzle are closely connected. When in use, the new submerged nozzle is inserted into the molten steel in the mold 4, and the molten steel in the mold 4 rotates under the action of the electromagnetic stirring of the mold, and the inclusions in the molten steel will accumulate toward the center, and the lower part of the nozzle 3 The inclusion capturing device collides and is captured by it, and adheres to the surface of the inclusion capturing device, thereby effectively removing inclusions from molten steel.

During the reaction process, the inclusions in the molten steel gather on the surface of the lower part of the nozzle (3) due to the rotation of the molten steel caused by electromagnetic stirring, so that the inclusions in the molten steel gather toward the center of the crystallizer, and the nozzles with multiple side outlet holes This rotation effect can be increased.

Inclusions such as alumina and silica in molten steel are easily adsorbed by basic oxides such as calcium oxide to form composite inclusions of calcium oxide and alumina, calcium oxide and silica. The surface of the nozzle is coated with calcium oxide coating to improve the adsorption capacity of the nozzle to inclusions such as alumina and silicon oxide. But the calcium oxide coating itself is not consumed.

With the increase of inclusions such as alumina and silicon oxide on the surface of the nozzle, these inclusions will continue to cover the alumina and silicon oxide on the surface of the nozzle.

The upper part 2 of the nozzle 1 and the lower part 3 of the nozzle 1 of the new submerged nozzle 1 can be an integral type (see Figure 2), or a combination of the two connected (see Figure 3 or 4); the materials of the two can be the same, or can be different. When the upper and lower parts of the new submerged nozzle 1 are combined, the connection between the upper part 2 of the nozzle and the lower part 3 of the nozzle can be fixed connection, such as pressing or casting (see Figure 3), or Use non-fixed connections, such as threaded connections (see Figure 4).

In order to improve the ability of trapping inclusions in the lower part 3 of the nozzle, the lower part 3 of the nozzle can be made into different shapes, such as the lower part 3 of the nozzle can be made into the same columnar shape as the upper part 2 of the nozzle (see Figure 1), or it can be made into The top is large and the bottom is small (see Figure 6); the bottom of the nozzle lower part 3 can also be made into a hollow structure 8 (see Figure 4). The outer surface 9 of the nozzle lower part 3 can be made smooth, and can also be made into a raised block (see Figure 5) or a groove (see Figure 6).

The length L of the novel submerged nozzle bottom 3, namely the length from the lower edge 7 of the nozzle top 2 to the lower end of the nozzle bottom 3 is 50-300mm. The purpose of effectively prolonging the length of the lower part 3 of the nozzle is to increase the chance of collision between the inclusions accumulated in the center of the molten steel and the inclusion capture device of the lower part 3 of the nozzle in the effective area of electromagnetic stirring.

Some existing submerged nozzles will break up the inclusions accumulated in the center of the molten steel when the vertically downward molten steel outlet is used. Therefore, the molten steel outlet holes of the new submerged nozzle are arranged on the side wall of the nozzle. . There are two or more outlet holes 5 on the side of the nozzle (see Figure 7). In the top view direction, the centerline of the outlet hole 5 on the nozzle side and the centerline of the nozzle form an included angle α of 0-35°. The purpose of choosing a certain angle a is to make the molten steel flowing out from the nozzle side outlet hole 5 coincide with the rotation direction of the molten steel caused by electromagnetic stirring, and to improve the effect of electromagnetic stirring. In the vertical direction, the center line of the exit hole 5 on the side of the nozzle can form an included angle β of 0-30° with the horizontal line (see FIG. 3 ). The setting of β angle is to improve the ability of molten steel to melt mold slag, and at the same time prevent the generation of slag entrainment.

The distance h between the lower edge of the nozzle side outlet hole 5 of the novel submerged nozzle 1 and the lower edge 7 of the nozzle upper part 2 is 20-80mm.

The material of the upper part 2 of the nozzle can be aluminum-carbon, aluminum-zirconium-carbon, magnesium-carbon, aluminum-calcium, fused quartz, etc.; the material of the lower part 3 of the nozzle can be the same material as that of the upper part 2 of the nozzle. Zirconia, calcium oxide, magnesium oxide, aluminum oxide, silicon oxide, etc., or a combination of two or more thereof may be used.

In order to improve the ability of the new submerged nozzle to capture inclusions, the outer surface of the lower part 3 of the nozzle can be coated with a thickness of 1-3mm, and the material is calcium oxide, or calcium oxide plus magnesium oxide, or calcium oxide plus silicon oxide. coating.

In order to improve the service life of the new submerged nozzle, an anti-corrosion ring made of zirconium or zirconium carbon can be set outside the nozzle on the part of the slag line that is in contact with the steel and slag.

Claims (17)

1. method of catching the continuous casting field trash, it is characterized in that: use one to have the novel submersed nozzle (1) of catching continuous casting field trash function, this submersed nozzle is made up of two parts up and down: top, the mouth of a river (2) have mouth of a river side to portal (5), have conventional molten steel diversion function; Top, the mouth of a river (2) increases a bottom, the mouth of a river (3) that closely links to each other, this bottom, mouth of a river (3) has the field trash of catching function, make the field trash in the rotation molten steel be caught and accumulate in the outer surface (9) of bottom, the mouth of a river (3), play the effect of effectively removing to remove in the molten steel field trash by bottom, the mouth of a river (3).

2. the method for claim 1, it is characterized in that: L/h=2.5-15 in the described submersed nozzle, wherein h portals the lower edge of (5) to the distance of (7) following along the line of top, the mouth of a river (2) for mouth of a river side, and L is following (7) along the line on top, the mouth of a river (2) length to lower end, bottom, the mouth of a river (3).

3. the method for claim 1 is characterized in that: the outer surface in bottom, the mouth of a river (3) applies the coating that contains calcium oxide, and the aluminium oxide, the silica that are used for adsorbing molten steel are mingled with, and forms the duplex impurity of calcium oxide and aluminium oxide, calcium oxide and silica.

4. method as claimed in claim 3 is characterized in that: the described coating that contains calcium oxide is that thickness 1-3mm, material are that calcium oxide or calcium oxide add the coating that magnesia or calcium oxide add silica.

5. one kind has the novel submersed nozzle (1) of catching continuous casting field trash function, and it is made up of two parts up and down, and it is characterized in that: top, the mouth of a river (2) have mouth of a river side to portal (5), have conventional molten steel diversion function; Top, the mouth of a river (2) increases a bottom, the mouth of a river (3) that closely links to each other, this bottom, mouth of a river (3) has the field trash of catching function, make the field trash in the rotation molten steel be caught and accumulate in the outer surface (9) of bottom, the mouth of a river (3), play the effect of effectively removing to remove in the molten steel field trash by bottom, the mouth of a river (3).

6. novel submersed nozzle as claimed in claim 5 (1), it is characterized in that: L/h=2.5-15 in the described submersed nozzle, wherein h portals the lower edge of (5) to following along the line 7 the distance of top, the mouth of a river (2) for mouth of a river side, and L is following (7) along the line on top, the mouth of a river (2) length to lower end, bottom, the mouth of a river (3).

7. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: top, the mouth of a river (2) and bottom, the mouth of a river (3) are a monoblock type or combined type that both are connected; Both materials are identical or different.

8. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: top, the mouth of a river (2) were fixedly connected or removably connect with being connected of bottom, the mouth of a river (3).

9. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: bottom, the mouth of a river (3) are column identical with top, the mouth of a river (2) or up big and down small platform shape.

10. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: the bottom of bottom, the mouth of a river (3) is the hollow-core construction (8) of indent.

11. novel submersed nozzle as claimed in claim 1 (1) is characterized in that: the outer surface (9) of bottom, the mouth of a river (3) is smooth or the bulk or the channel form of band projection.

12. novel submersed nozzle as claimed in claim 6 (1), it is characterized in that: in use, it is that to keep the portal upper edge of (5) of the molten steel side at the mouth of a river be 50-150mm to the distance H of liquid steel level (6) that submersed nozzle (1) inserts the degree of depth in the molten steel, and L is 50-300mm, and h is 20-80mm.

13. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: in top, the mouth of a river (2) mouth of a river side portal (5) be two or more; Overlook on the direction, mouth of a river side is portalled, and become value with the center line at the mouth of a river be 0-35 ° angle α for the center line of (5); In vertical direction, mouth of a river side is portalled, and become value with horizontal line be 0-30 ° angle β for the center line of (5).

14. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: the material of top, the mouth of a river (2) is a kind of in aluminium-carbonaceous, aluminum-zirconium-carbonaceous, magnesium-carbonaceous, aluminium-calcareous, the vitreous silica matter.

15. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: the material of bottom, the mouth of a river (3) is zirconia, calcium oxide, magnesia, aluminium oxide, silica etc., or they two or more combination.

16. according to the described novel submersed nozzle of claim 5 (1), it is characterized in that: the outer surface coating thickness in bottom, the mouth of a river (3) is that 1-3mm, material are that calcium oxide or calcium oxide add the coating that magnesia or calcium oxide add silica, the aluminium oxide, the silica that are used for adsorbing molten steel are mingled with, and form the duplex impurity of calcium oxide and aluminium oxide, calcium oxide and silica.

17. novel submersed nozzle as claimed in claim 5 (1) is characterized in that: in the slag line part that contacts with slag with steel, at the anti-erosion ring of the outside at mouth of a river edge cover zirconium matter, zirconium carbonaceous.

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