TW487736B - Ladle refining apparatus and ladle refining method using this apparatus - Google Patents

Abstract

A ladle refining device for restricting in-tank metal deposition and for efficiently agitating molten steel, refining slag and degassing; and a ladle refining method using it. A device for refining molten steel by directly connecting for communication a vacuum/depressurized tank (2) to the upper part of a ladle (1) and by blowing an agitation gas (6) consisting of an inert gas into the ladle, wherein an inner diameter of a vacuum/depressurized tank trunk is set to be up to that of the upper end of the ladle and to be at least a projected section diameter of a swelled portion (7) of the molten steel surface caused by the agitation gas (6) blown into the ladle.

Description

487736 A7 _ B7 V. Description of the invention (1) The present invention relates to a bucket refining device and a method for refining a molten steel. In recent years, the quality requirements of steel products have become more stringent with the use of advanced and diversified technologies, and the demand for high-purity steel manufacturing has become increasingly high. In response to the demand for such high-purity steels, manufacturing engineering has been seeking to expand the melt preparation and secondary refining equipment. In particular, the secondary refining equipment is for the purpose of degassing and removing inclusions of molten steel. Generally, there are vacuum refining equipment such as RH and DH, arc heating slag refining equipment represented by LF, etc., which are required when manufacturing high-purity steel such as bearing steel. Generally, treatment methods such as LF and RH are performed. However, for example, the RH vacuum refining equipment inserts the immersion tube into the molten steel in the hopper, and the equipment that sucks the molten steel into the vacuum tank through the immersion tube for vacuum refining treatment. Because the stirring ability of the molten steel in the hopper is small, Insufficient stirring of the slag on the surface of the molten steel outside the immersion tube makes it impossible to fully perform the slag modification, and the slag will oxidize the molten steel due to the high degree of oxidation, and it will be oxidized by sticking to the substrate in the vacuum tank. There is a limit to the refining ability of inclusions due to the reaction between the steel and the molten steel in the vacuum tank to cause the molten steel to be oxidized. In addition, in order to avoid the deterioration of the purity of molten steel caused by reoxidation caused by slag, although the method of reducing the oxidation degree of slag is generally adopted by using LF equipment, etc., this method has a prolonged processing time and the resulting heat loss. • The problem of increasing costs such as refractory loss. From this point of view, in the conventional technology, the method of directly reducing the surface of molten steel in the hopper and performing the reaction between slag and molten steel under vacuum has been developed. VOD method, VAD method, SS-VOD method, etc. . In order to directly decompress the inside of the funnel _ The means for the steel surface is to contain the funnel in a decompression capacity that can hold the whole of the funnel. The paper size applies the Chinese National Standard (CNS) A4 (210 X 297 mm) (please first Read the back --- II ---------------. Please fill in this page for the precautions) • Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs -4- Intellectual Property of the Ministry of Economic Affairs Printed by the Bureau ’s Consumer Cooperatives 487736 Α7 _____ ___ Β7 V. Description of the Invention (2) The method of reducing the pressure of the entire hopper in the vessel and the use of the hopper itself as the lower decompression tank 'close to the upper decompression tank on the top of the hopper A method for reducing the surface of molten steel in a decompression hopper. Either method has complex equipment and structural restrictions. In order to prevent the scattering of molten steel or slag, there is a problem that a large number of gas cannot be circulated and stirred. Due to productivity, equipment costs, and maintenance considerations, it cannot be widely considered. situation. From this point of view, there is a method of accommodating the entire funnel in a vacuum / decompression container that can accommodate the entire funnel, so as to promote decompression of the entire funnel. In the vacuum tank, a tube with sufficient freeboard is installed. It can cope with the scattering of molten steel and slag forming during vacuum processing, and it is disclosed in JP 9-1 1 1 3 3 1 to shorten the processing time. However, 'this method is a method in which the vacuum container is divided into two parts, the inner diameter of the vacuum tank is larger than the shape of the upper end of the hopper, and the entire hopper is installed in the vacuum tank for refining. The lower end of the tube is tightly connected to the upper end of the hopper or dipped in the slag and molten steel in the hopper, so that when refining under vacuum, if the molten steel scatters the base material, the fitting of the internal piping cannot be detached or immersed in the hopper Sometimes there is a risk that the substrate will contaminate the molten steel. Furthermore, the viewpoint of ensuring the molten steel temperature when the processing time is extended is also problematic. The method of using the pouring bucket itself as the lower pressure reducing tank to promote close contact between the top of the pouring bucket and the upper reducing groove to reduce the surface of the molten steel in the pouring bucket is described in "Materials and Treatment Vol. 3, No. 1, 1990 Ρ250" (Issued by Japan Iron and Steel Association), a middle cover is installed on the top of the hopper to prevent splashing from the surface of the molten steel caused by gas sprayed from the bottom of the hopper and directly scattered to the close contact between the hopper and the upper decompression tank. (Seal section of the hopper) At the same time, the paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm). Please read the note on the back-to-back page t · 丄 ίPage I-1 IIIIII Order 4- 5- 487736 Printed A7 B7_ by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the Invention (3) Install a shield on the top of the pouring bucket to prevent splashing and jumping to the sealed portion of the bucket. However, the present invention has the problem that the molten steel scatters the base material, which makes it difficult to install and remove the middle cover, and the shielding plate also sticks to the molten steel, which also causes the problem of the refractory cost of the shielding plate itself. Moreover, it is necessary to attach and remove the middle cover and the shielding plate each time the vacuum tank is processed, so there is also a problem of poor workability. The present invention provides a ladle refining device and a ladle refining method using the same, which can easily solve the problems of the conventional methods. That is, the present invention is a method for completely improving the operation obstacle by suppressing the sticking of the molten steel caused by the scattering of the molten steel which is a problem in the conventional refining method of the ladle. Degassing, so that the bucket refining device and the bucket refining method can effectively manufacture high-purity steel and can greatly improve the heat melting degree. The present invention is an impregnation tube without a bottom end immersed in the molten steel 4 in the bucket. The vacuum and decompression tank 2 is directly connected to the top of the hopper 1 in the decompression tank, and by injecting inert gas into the hopper, the molten steel in the hopper is stirred to refine the molten steel in the hopper. The top of the hopper is tightly combined with the vacuum and decompression tank to form a sealed structure, and the inner diameter of the abdomen of the vacuum and decompression tank is smaller than the inner diameter of the top of the hopper, which is produced by spraying and stirring gas into the hopper. The molten steel liquid level bulge 7 in the bucket has a projected cross-sectional diameter or more, and the height to the top of the vacuum / decompression tank 2 is a vacuum / decompression refining device characterized by the molten steel liquid level in the bucket above 5 meters. Furthermore, a cylindrical portion 9 is provided at the bottom end of the vacuum and decompression tank 2. The cylindrical portion has an inner diameter above the projected section diameter of the molten steel bulge in the hopper and an outer diameter below ιη inside the top of the hopper, and the circle The bottom position of the same part is not located at the top of the paper. The paper size is fine Chinese National Standard (CNS) A4 specifications (210 father 297 public love). L · .— »! 装 -------- Order— ( Please read the precautions on the back before filling this page) Line · 丨 -6- 487736 A7 ___ B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the invention (4) The lower end is not immersed in the melting furnace. A vacuum / decompression device featuring steel. Furthermore, the present invention is also a burner 10 in a vacuum / decompression tank that burns fuel and oxygen from its lower end to emit flame, and can perform heating of molten steel 4 and Vacuum and decompression device for heat preservation in vacuum and decompression tank. In order to use the heating burner 10 to emit flame from the bottom end, the temperature of the inner wall of the vacuum-decompression tank is constantly maintained above 1000t during continuous use. Refining method. When the vacuum refining device is used in the present invention, the method of refining the dregs is characterized by controlling the amount of slag on the molten steel level in the hopper to meet the following conditions and refining. 0. 010 ^ H / h ^ 0. 025 Η; thickness of slag in the funnel, h: the depth of the molten steel bath in the funnel is to add A 1 to the molten steel, and by supplying oxygen to promote the combustion of the added A 1 ' It is a method of refining with a bucket featuring the pressure in the vacuum and pressure reduction tank to be 760T0 ~ 500To rr when the molten steel is raised. Brief description of the drawings [Fig. 1] is a sectional view of an embodiment of the apparatus of the present invention. [Fig. 2] A cross-sectional view when a cylindrical portion is provided inside a vacuum cover of the apparatus of the present invention. [Figure 3] Sectional view of the heating burner installed in the device of the present invention, read the notes on the back, and then fill out this page) r · installation ---- booking --------- line · This paper size is applicable Chinese National Standard (CNS) A4 specification (210 X 297 public love) 487736 A7 B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the invention (5) [Fig. 4] For the refining of molten steel using the device of the present invention The relationship between the ratio of slag thickness Η in the ladle and the depth h of the molten steel bath (H / h) and various refining efficiency are shown. [Fig. 5] A comparison diagram between the conventional method of bearing steel product T · 0 and the method of the present invention. [Fig. 6] This is a display diagram of the refractory temperature and the thickness of the base material inside the vacuum-decompression tank of the device of the present invention. [Fig. 7] A diagram showing the pressure and splash height in the tank when oxygen is sprayed on a molten steel containing A 1 by using the device of the present invention. Explanation of drawing number] 1 Funnel 2 Vacuum · decompression tank 3 Stirring gas injection spark plug 4 Dissolved steel 5 Slag 6 Stirred gas 7 Dissolved steel liquid level bulge produced by stirring gas 8 Sealing material 9 Cylinder part 10 Heating and burning The embodiments are explained in detail below. Fig. 1 is a specific example of the bucket-chain fine chain device of the present invention. This device is made of hopper 1 and vacuum decompression tank 2. The paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) Please read _ first. Sj's note! F IOrder 4- 8-487736 Α7 _ Β7 V. Description of the invention (6) Composition 'The bottom of the hopper is equipped with a stirring gas injection device 3. The method for stirring the molten steel 4 in the hopper of the present invention is not limited to this. Then, the inner diameter of 腹部 δ in the abdomen of the vacuum and decompression tank is smaller than the inner diameter of the upper end of the bucket, which is smaller than the projected cross-sectional diameter D of the molten steel level rise portion 7 in the bucket. The projected cross-sectional diameter of the molten steel liquid level bulge is expressed by the following formula when the gas is sprayed and stirred from the bottom of the hopper. D = d + 2htanl2. D; diameter of projected section of painted surface bulge, d; diameter of gas spark plug h; depth of molten steel bath in the funnel tightly combines the top of the funnel with the vacuum and decompression tank, and applies a seal structure that can maintain the target vacuum . Then, the gas is stirred and sprayed from the bottom of the hopper to stir the molten steel in the vacuum and decompression tank under normal pressure or vacuum. Although the molten steel level rises under high vacuum, the molten steel and slag 5 will scatter. However, the device of the present invention can reduce the internal diameter of the vacuum and decompression tank to a smaller diameter than the top of the bucket. D. The adverse effects caused by the molten steel and slag scattering from the sealed part of the funnel and vacuum / decompression tank are minimized. The scattering of molten steel and slag caused by flying splashes is scattered from the molten steel liquid level bulge 7 upward, and then turned downward to reach the bucket seal. In the present invention, since there is a vacuum-decompression tank belly with an inner diameter smaller than the inner diameter of the upper end of the hopper, a fly-up fly slams into the abdominal-wall of the vacuum-compression tank and falls as it is. Because the surface of the steel is melted in the hopper, the fly can not reach the seal part of the hopper. In addition, if most of the splashes collide with the shielding plate when using the shielding plate, one part is solidified on the surface of the shielding plate and becomes the base material. However, the present invention does not make the shielding plate free of this phenomenon, and vacuum and decompression The shape of the inner diameter of the groove is small. The paper size applies to the Chinese National Standard (CNS) A4 (210 X 297 mm).

Please read the back first, note S ·, tiling page II order 4 Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs-9- 487736 Printed by the Consumers’ Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 _____B7__ V. Description of the Invention 7) It is easy to keep the inner temperature at high temperature, so the speed of splashing, solidifying and growing into a base material when colliding with a vacuum is extremely slow, and the yield is shortened by the shape of the abdomen of the vacuum decompression tank, which shortens the exhaust capacity to reach the vacuum Initial exhaust time. More shield-free board installation Operation and cost deterioration. The reason why the projected cross-sectional diameter of the molten steel liquid level bulge above the abdomen of the vacuum and decompression tank is because the slag scattering mainly occurs in the molten steel liquid level bulge. Also shown in Figure 2 is the bottom of the vacuum / decompression tank set at the bottom of the patent application scope. The bottom end is located at the cylinder portion of the cylindrical portion 9 of the molten steel 4 and slag 5 which is not impregnated in the hopper. The 9 series has a projection section diameter 7 of the molten steel in the hopper and has an outer diameter below the inside diameter of the top end of the hopper, and is manufactured by using refractory or coating the surface of the substrate with refractory. With this, compared with the method shown in Figure 1, it can reduce the adverse effects on the molten steel and slag scattering of the hopper and the vacuum sealing part, and can try to reduce the productivity (t / C Η) improvement and melting caused by pouring. The refining efficiency due to the increase in steel is further improved. The reason why the cylindrical slag 5 or the molten steel 4 is not used here is that a sufficient effect can be exerted at the bottom end of the cylindrical portion as long as it is lowered, and the cost is deteriorated when it is impregnated. From the point of view of pure steel manufacturing, all the slag on the steel surface is stirred to promote the slag modification of slag 5 and molten steel 4. The slag modification of the dipping method outside the dipping tube is not sufficient, so it is not The dipping method is more advantageous. The sealing method between the funnel 1 and the vacuum and decompression tank is in accordance with the Chinese National Standard (CNS) A4 (210 X 297 mm) in this paper. The loss in the abdomen of the decompression tank is small. The inner diameter, which is relatively small and can be placed, is formed below the end of the molten steel and the present invention and is exemplified. Inner fires above this circle diameter are made into a cylindrical part at 9 o'clock. • Decompression tanks, freeboard volume, volumetric gas injection part is immersed at the top of the pouring ladle to cause the refractory to fully react in the ladle with stirring force. Minor inventions are not special

Please first — read the precautions on the back and the front. J Page I. Order 4 -10- 487736 A7 V. Description of the invention (8) Other restrictions, but consider that when the freeboard height of the bucket is insufficient and the sealed part occurs in the bucket For the heat resistance of molten steel or slag when it flows out, it is better to use asbestos or metal A 1 with better heat resistance. The sealing material is more appropriate. When using rubber-based sealing materials, heat-resistant treatment such as double sealing with asbestos on the side of the bucket is appropriate. The sealing position is not limited to the top of the hopper, and the sealing position is set at a position where the outside of the hopper is slightly lowered from the top of the hopper, and it is also possible to form a structure that can prevent the sealing member from directly receiving the radiation heat of the molten steel. Included in the present invention. The vacuum / decompression tank 2 is suitable to have sufficient height for molten steel and slag scattering during vacuum processing. In the present invention, the height of the vacuum / decompression tank is specified to be 5 m or more. When the height of the vacuum / decompression tank is less than 5m, the vacuum / decompression tank top cover will stick to the substrate or the vacuum / decompression tank will block the abdomen, and the substrate will enter the exhaust pipe, which will cause a significant deterioration in production efficiency. And increase equipment maintenance costs. There is no special upper limit for the height of the vacuum and decompression tank. However, if it is too high, it is necessary to pay attention to the increase of the exhaust volume and the increase of the initial exhaust time. Fig. 3 is an example of the configuration of the burner 10 which burns fuel gas and oxygen in a vacuum and decompression tank and heats it. The heating burner 10 is used to heat the refractory in the vacuum and decompression tank during processing and non-processing, so that the temperature of the refractory in the tank is always maintained at a high temperature, and the refractory in the tank can be more inhibited from sticking to the substrate. In order to avoid the limitation of the molten steel pollution caused by sticking to the substrate and the continuous treatment of dissimilar steel, and to avoid the decline in productivity due to the removal of the substrate. In order to obtain sufficient substrate adhesion prevention effect, the refractory temperature on the inner wall of the tank must be kept above 100 ° C. In addition, the inside of the decompression tank is heated by a burner during processing and non-processing, and is often maintained at a high level.

Please read the precautions of the back © before I fill in V. Write the page II. Order 4 Printed by the Intellectual Property Bureau Staff Consumer Cooperatives of the Ministry of Economic Affairs This paper is printed in accordance with China National Standard (CNS) A4 (210 X 297 mm) -11 -Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 487736 A7 B7 V. Description of the invention (9) Temperature can reduce the temperature drop of the molten steel during processing. When using the apparatus of the present invention for refining molten steel, by adjusting the amount of slag on the molten steel level in the ladle to the following condition range, efficient refining can be performed. 0. OlO ^ H / h ^ O. 025 Η; The thickness of the slag in the hopper, h; The reason for the depth of the molten steel bath in the hopper to limit the H / h range is as follows. If the thickness of the slag is thicker than 0.025, the molten steel liquid level is covered by the slag during vacuum refining, so that the surface area of the molten steel exposed to the vacuum is small, and sufficient dehydrogenation cannot be obtained. effectiveness. For another example, when the thickness of the slag is thinner, the contact area between the slag and the molten steel is smaller than H. 0 10, and the inclusion capacity of the slag is reduced, and sufficient deoxidation efficiency cannot be obtained. Therefore, in the refining of pure steel, it is appropriate to adjust the slag thickness within the above range. In addition, the device of the present invention can be equipped with a heating burner 10 at the upper end of the tank to supply only oxygen to promote the combustion of A 1 in the molten steel, and the molten steel is heated by its reaction heat. In addition, the conventional method of blowing oxygen on RΗ is to introduce the molten steel into the reaction tank at least so that the pressure in the tank is below 200 t 〇rr. Therefore, the oxygen that has increased in volume under reduced pressure will disperse the molten steel. Or, the C 0 gas produced by the reaction of oxygen with carbon in the molten steel promotes the spattering of the molten steel, which greatly spatters. In view of this, the pressure in the tank when the device of the present invention performs the process of supplying oxygen to the molten steel may be lower than atmospheric pressure, so the pressure of the oxygen in the tank is 500 t rr or more and 7 60 t ◦ rr or less. 1 liter of heat to minimize splashing. If the pressure in the tank is set below 760 t 〇rr, it is because the pressure in the tank is above atmospheric pressure. The size of this paper applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) ---.--- ^ ----.-- install -------- order ----- (please read the precautions on the back before filling this page) line, -12- 487736 A7 ------- B7 _ _ 5. Description of the invention (10) In the state of the invention, burning of the sealing material due to high-temperature gas emission in the groove of the vacuum sealing part will occur. Also, the device of the present invention may be provided with a metal wire adding device that uses a metal wire covered with an element with a high vapor pressure element such as ca to cover it with an iron sheet. After refining under reduced pressure, it is preferable to continue the process at atmospheric pressure. Example When the converter is decarburized and refined, Mn alloy 6 · 8kg / t, Si alloy 2 · 7kg / t, and aluminum 0 · 4 5kg / t are added based on the purity of each alloy, and the slag composition is controlled. The molten steel with caO3 · 0 kg / t added was refined using the apparatus of the present invention shown in Fig. 3 and compared with the conventional RH processor. Table 1 shows the manufacturing conditions and results of the examples of the present invention, and Table 2 shows the manufacturing conditions and results of the comparative examples. Please read it first, fill in the notes of Sj, I install the page I w IIIIII Order printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs This paper is printed in accordance with China National Standard (CNS) A4 (210 X 297 mm) 487736 Printed by the Consumers' Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the invention (11) [Table 1] The steel type S 4 5 C according to the embodiment of the present invention, the amount of molten steel 2 8 0 butyl 0 N depth of molten steel bath 3.7 2 Omm Achieved vacuum degree 0.6 T 〇rr Vacuum exhaust treatment time 2 1 minute A r gas flow rate 3 0Nm3 / H i · (injection of gas at the bottom of the funnel) molten steel composition C Si Μη Ρ SH 〇0.30% 0.19 % 0.73% 0.008% 0.013% 3.5ppm 35ppm slag composition T.Fe Ca〇Si〇2 Ah〇3 Mn〇Mg〇S 1.26% 44.59% 14.02% 26.51% 0.73% 5.02% 0.08% slag thickness 60mm temperature 1575 〇 C treatment molten steel composition C Si Μη Ρ SH 〇0.44% 0.20% 0.75% 0.008% 0.020% l.lppm 8ppm slag component T.Fe Ca〇Si〇2 Ab〇3 Mn〇Mg〇S 0.24% 40.12% 4.35 % 38.65% 0.21% 6.52% 1.54% slag thickness 70_ temperature 1553 1: --------------- install -------- order --------- line ·, _ Please read the precautions on the back before filling in this Page) This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) -14-487736 A7 B7 V. Description of the invention (12) [Table 2] Conventional method R Η Example Vacuum degree reached by steel bath depth Vacuum exhaust treatment time A r Gas flow rate S 4 5 C 2 7 8 T 〇N 3. 7 0 0 mm 〇. 6 T orr 2 3 minutes Please read the notes on the back & Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 1 1 〇Nm3 / H r (RH reflow gas) C Si Mn PSH before processing 〇0.29% 0.18% 0.73% 0.007% 0.020% 3.6ppm 31 ppm slag Composition T.Fe Ca〇S1O2 AI2O3 Mn〇Mg〇S 1.54% 42.18% 13.97% 28.49% 0.80% 4.87% 0.08% Slag thickness 60mm Temperature 1585 t C Si Mn PSH molten steel composition 0.45% 0.19% 0.76% 0.007% 0.016% 1.2ppm 18ppm Slag composition T.Fe Ca〇Sl02 AI2O3 Mn〇Mg〇S 1.40% 38.38% 14.08% 31.36% 1.10% 4.75% 0.09%

Residue thickness 60_ Temperature 155CTC This paper size is applicable to Chinese National Standard (CNS) A4 (210 X 297 mm) -15- 487736 A7 _______ B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the invention (13) Disposal The following hydrogen hydrazones, the examples of the present invention, and the comparative examples are of the same good level. The treated oxygen gas was very good at 8 p p m for the comparative example of 18 p pm. The T · F e of the slag composition after treatment is higher than that of the comparative example 値 1 · 40% The present invention can achieve T · F e 0 · 2 because the reaction between the slag and the molten steel is fully performed in the hopper. 4% is very low, so it can reduce the slag oxidation degree and promote the reduction of oxygen concentration in molten steel. By using the device of the present invention, it is possible to achieve a low hydrogenation equivalent to the conventional RH method and obtain a steel with higher purity than the conventional RH method. Fig. 4 is a graph showing the relationship between the ratio (H / h) of the thickness of the slag in the hopper to the depth h of the molten steel bath and the dehydrogenation efficiency and deoxidation efficiency when the device of the present invention is used for vacuum refining. The surface of the molten steel in the range of H / h > 〇. 25 is also covered with slag during vacuum treatment, so that the sufficient dehydrogenation efficiency cannot be obtained because the surface area of the molten steel exposed to the vacuum is small. In addition, in the range of H / h < 〇. 〇 〇 0%, because the amount of slag is small, sufficient reaction surface area of slag and molten steel cannot be obtained, so sufficient deoxidation efficiency cannot be obtained. Figure 5 shows the bearing. For steel, it is known that the LF-R method used to obtain high-purity steel is compared with the total oxygen of the product when refining using the device of the present invention. By using the device of the present invention, high-purity steel equivalent to or more than conventional can be obtained in the manufacture of high-grade steel such as bearing steel, and the manufacturing cost can be reduced because the L F project is omitted. Figure 6 shows the effect of the heating burner in the tank of Figure 3. By using a burner in the tank to keep the temperature of the refractory on the inner wall of the vacuum and decompression tank above 1000 t, the amount of sticking of the substrate can be significantly reduced. (Please read the notes on the back before filling this page) ^ ----

The paper size of IIII line is applicable to Chinese National Standard (CNS) A4 (210 X 297 mm) -16- 487736 A7 B7 V. Description of the invention (14) Figure 7 shows the use of the device shown in Figure 3 for heating molten steel Shows the relationship between the pressure in the tank and the height of the splash when the oxygen is supplied to promote the combustion of A 1 in the molten steel for the heat treatment of the molten steel. By forming the pressure in the tank to be more than 500 t 〇 r I *, it is possible to reduce the splash to a higher level and reduce the amount of sticking of the substrate in the tank than the conventional R method. According to the device of the present invention and the refining method using the device, the adverse effects caused by the scattered molten steel which is a problem in the conventional ladle refining method to the sealed portion of the ladle can be avoided. At the same time, the amount of substrate sticking in the tank can be reduced. And reduce the temperature drop of the molten steel during processing. In addition, in the manufacture of steel requiring high purity, the efficiency of the manufacturing process can be promoted by using the same refining device to reduce the oxidation degree of the slag to modify the slag and the degassing process. -— — — 1ι-*-ιιιι — · IIII II I β I l · (Please read the notes on the back before filling out this page) Printed on paper standards of the Ministry of Economic Affairs, Intellectual Property Bureau, Employee Consumer Cooperatives This paper applies Chinese national standards (CNS ) A4 size (210 X 297 mm) -17-

Claims (1)

487736 ABCD is filling and repairing the printing of employee consumer cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs of the Sun and the Moon. VI. Patent Application Annex No. 89109391 Patent Application Chinese Application for Patent Scope Amendment March 1991 Amendment 1. A vacuum decompression refining device The vacuum decompression tank with the bottom end not immersed in the molten steel immersion tube in the hopper is directly connected to the top of the hopper to reduce the pressure in the tank, and the inert gas is sprayed into the hopper to stir the hopper. A device for melting steel for refining molten steel in a funnel, which is characterized by tightly joining the top of the funnel to a vacuum / decompression tank to form a sealed structure, and the inner diameter of the abdomen of the vacuum · decompression tank is larger than the top of the funnel. The inner diameter is small, which is greater than the projected cross-sectional diameter of the bulge of the molten steel level in the hopper caused by gas blowing and stirring in the hopper, and the height of the top of the vacuum and decompression tank from the molten steel level in the hopper is 5 More than meters. 2 · The vacuum and decompression refining device according to item 1 of the scope of the patent application, wherein a cylindrical cylinder is installed at the bottom of the vacuum and decompression tank, and the cylinder has a diameter greater than the projected section diameter of the molten steel bulge in the bucket The inner diameter is the outer diameter below the inner diameter of the top of the hopper, and the bottom end of the cylindrical part is not located below the top of the hopper, and is not immersed in the cast inner molten steel. 3 ‘A vacuum / decompression refining device such as item 1 or 2 of the scope of patent application, where the vacuum / decompression tank is provided with a burner that burns fuel and oxygen from its lower end to emit flame. 4 · A ladle refining method using the vacuum / decompression refining device in the first patent application scope, which controls the amount of slag on the molten steel level in the ladle to meet the following conditions. This paper size is applicable to Chinese National Standard (CNS) A4 specification (210 x 297 mm) 11, ------ installed ------ ordered ------ line (Please read the precautions on the back before reading (Fill in this page) 487736 A8 B8 C8 ____ D8 6. The scope of patent application: 0. OlO ^ H / h ^ O. 025 Η; thickness of slag in the funnel h: depth of molten steel in the funnel 5 ·-application patents The method of bucket refining of the vacuum / decompression refining device in the third item is the continuous use of the temperature of the inner wall of the vacuum / decompression tank by the flames sprayed from the bottom by the burner arranged in the vacuum / decompression tank. Medium is often kept above 1000 ° C. 6. — A method of refining the hopper using the vacuum / decompression refining device in the scope of patent application No. 1 is to add A 1 to the molten steel and supply oxygen to promote the combustion of the added A 1 to heat the molten steel. At that time, the pressure in the vacuum and decompression tank was controlled to 760 t ο r to 500 t rr. ---, Γί ---- Packing ------ Order ------ line (Please read the notes on the back before filling this page) Applicable to China National Standard (CNS) Α4 specification (210 × 297 mm) -2-