JP6578939B2 - Top blowing lance for converter blowing and converter blowing method - Google Patents

Description

  The present invention relates to an upper blowing lance for converter blowing for performing oxidizing refining by blowing an oxidizing gas to molten metal in the converter, and a converter blowing method using the same.

  A converter-type refining furnace (converter) is used as a refining furnace for producing molten steel by removing impurities from the hot metal produced in a blast furnace. In the top-bottom blowing converter or top-blowing converter, the molten metal is charged into the converter type refining vessel, and oxygen gas is blown to the molten metal from the top blowing lance disposed in the upper portion of the converter type refining vessel. Is removed by oxidation. When refining hot metal containing a large amount of P and C as impurities in a converter-type refining vessel, converter dephosphorization refining is performed first, followed by decarburization refining. After dephosphorization refining, dephosphorization slag in the converter is discharged, and then decarburization refining may be performed again. In decarburization refining in a converter, oxygen gas is blown up from an upper blowing lance, and C in the hot metal is mainly removed as carbon monoxide.

  In order to improve the decarburization refining productivity in the converter-type refining vessel and at the same time reduce the manufacturing cost of molten steel, the so-called high-speed operation shortens the refining time by increasing the flow rate of top blowing oxygen from the top blowing lance. It is effective to perform blowing.

  As the flow rate of top blown oxygen is increased, the amount and distance of splashes of bullion, etc., from the converter furnace mouth to the outside of the furnace increase, and the lance, furnace body, or skirt or hood located above the furnace mouth increases. A large amount of bullion adheres, causing troubles such as cooling water leakage, increasing the non-operation time for removing the bullion and repairing the equipment, and reducing the productivity. Moreover, the amount of dust discharged to the outside of the furnace along with the exhaust gas increases as the flow rate of the top blown oxygen increases. The main component of the dust is iron oxide, and the refining yield in the converter decreases as the dust discharge increases.

  In Patent Document 1, when performing decarburization and refining of molten iron by blowing up an oxidizing gas, a Laval nozzle or a straight nozzle in which the inclination angle of the central axis of the nozzle with respect to the central axis of the upper blowing lance is 18 to 22 °, By using an upper blowing lance having four holes arranged around the central axis of the upper blowing lance, the amount of dust generated can be suppressed while maintaining high decarbonation efficiency.

  It is known that when the molten metal in the smelting vessel is stirred to perform the smelting, the molten metal in the vessel oscillates (sloshing) with stirring. Patent Documents 2 and 3 disclose a method for preventing rocking (sloshing) of the molten metal in the furnace generated by the action of the bottom blowing gas in the bottom blowing converter or the top bottom blowing converter. . Patent Document 4 describes sloshing when stirring and refining with hot metal ladle or torpedo car.

JP 2014-224309 A JP 09-176719 A JP 2012-237036 A JP 2014-031562 A

  By providing a nozzle with four holes around the center axis of the lance and refining the converter using an upper blowing lance in which the inclination angle of the center axis of the nozzle with respect to the center axis of the upper blowing lance is 18 to 22 °, Patent Document 1 As described in the above, generation of dust can be suppressed. On the other hand, if the amount of acid sent from the top blowing lance is increased using a lance having a four-hole nozzle, splashing of bullion will become more intense and not only will the refining yield decrease due to bullion loss, , Metal will adhere to the furnace body, skirt, and hood, increasing the time spent removing them, resulting in cost reduction.

  The present invention is a converter refining using a top blowing lance for a converter blowing having a four-hole nozzle around the center axis of the lance. It is an object of the present invention to provide a top blowing lance for converter blowing and a converter blowing method using the same.

That is, the gist of the present invention is as follows.
(1) In a top blowing lance for converter blowing having a total of four hole nozzles around the center axis of the lance,
The four-hole nozzle has an angle of the nozzle center axis with respect to the lance center axis (inclination angle α) of 10 ° or more,
The intersection of the plane of the lance tip perpendicular to the lance center axis (hereinafter referred to as “lance tip surface”), the lance center axis, and the nozzle center axis is defined as the lance center point and nozzle center point, respectively. The direction from the nozzle to the nozzle center point is the radial direction, and the angle between the radial directions of adjacent nozzles around the lance center point is the spread angle,
Of the four divergence angles formed by the four-hole nozzles, the two divergence angles facing the lance center point have a divergence angle of 95 ° or more and 120 ° or less. Top blowing lance.
(2) The top blow lance for converter blowing according to (1) above, wherein the sum of two spread angles adjacent to each other around the center point of the lance is 180 °.
(3) When performing decarburization blowing of hot metal in a converter-type refining furnace, the top blowing lance for converter blowing is used as the top blowing lance. The converter blowing method.

  By using an upper blowing lance for converter blowing with a four-hole nozzle around the central lance axis of the present invention, the occurrence of spitting can be suppressed even in high-speed blowing with a high upper blowing oxygen supply rate. The occurrence of gold loss can be reduced.

It is a figure which shows the nozzle arrangement | positioning of a 4-hole lance, (A) is AA arrow sectional drawing which shows a lance front-end | tip, (B) is a figure which shows the nozzle arrangement | positioning of a lance front end surface. It is a figure which shows the cross section of a converter.

  The present invention is directed to an upper blowing lance 1 for converter blowing (hereinafter also referred to as “four-hole lance 2”) having a four-hole nozzle 3 around a lance center axis 5. Hereinafter, description will be given based on FIGS. 1 and 2.

  In the top blowing lance 1 for converter blowing, the nozzle center axis 6 of the nozzle 3 arranged around the lance center axis 5 usually has an angle with the lance center axis 5. Here, the angle of the nozzle center axis 6 with respect to the lance center axis 5 is defined as an inclination angle α.

Here, the plane of the lance tip perpendicular to the lance center axis 5 is defined as “lance tip surface 4”. As shown in FIG. 1A, the outer shape of the lance tip is often rounded, but the lance tip surface 4 may be a plane including a portion where the nozzle 3 opens on the outer surface of the lance, for example (FIG. 1A). 1 (A)). FIG. 1B shows the lance tip surface 4. Assume that the intersections of the lance tip surface 4 and the lance center axis 5 and the lance tip surface 4 and the nozzle center axis 6 are a lance center point 7 and a nozzle center point 8, respectively. A direction from the lance center point 7 toward the nozzle center point 8 on the lance tip surface 4 is defined as a radial direction 9. On the lance tip surface 4, an angle between the radial directions 9 of the nozzles adjacent to each other around the lance center point 7 is defined as a spread angle β. As shown in FIG. 1B, the 4-hole lance 2 has four radial directions (9a, 9b, 9c, 9d) corresponding to the four-hole nozzles (3a, 3b, 3c, 3d), respectively. There are also four spread angles β. The four βs are named β ₁ , β ₂ , β ₃ , β _{4 in} the clockwise direction of the nozzle central axis. For example, the spread angles β ₁ and β ₃ are adjacent to the spread angle β ₂ around the lance central axis.

The four-hole lance 2 conventionally used has four radial directions (9a, 9b, 9c, 9d) orthogonal to each other on the lance tip surface 4, and β ₁ = β ₂ = β ₃ = β ₄ = 90 °. It was. The four nozzles (3a, 3b, 3c, 3d) have the same inclination angle α, and the nozzle center point (8a, 8b, 8c, 8d) is around the lance center point 7 on the lance tip surface 4. Those arranged concentrically were used.

  As described above, when the converter was blown using the four-hole lance 2 as the top blowing lance 1, a phenomenon was observed in which, when the amount of the top blowing acid was increased, the splash of the bullion became intense. As shown in FIG. 2, it is considered that the splash generated in the refining using the top blowing lance 1 is mainly generated at a fire point 14 where the top blowing jet collides with the molten metal 12. Then, the water generation | occurrence | production model experiment was investigated and the generation | occurrence | production behavior of the splash in the top blowing blowing using the 4-hole lance 2 was investigated.

The water model device is a 1/14 scale model of a 300-ton real converter. Regarding the four-hole lance 2 used, the nozzle 3 is a straight nozzle, the nozzle diameter is 2.5 mm, the inclination angle α of the nozzle 3 is 20 °, and the radial directions (9a, 9b) of the four nozzles on the tip surface 4 of the lance. , 9c, 9d) are orthogonal and β ₁ = β ₂ = β ₃ = β ₄ = 90 °. The four nozzles are named nozzle 3a, nozzle 3b, nozzle 3c, and nozzle 3d in the clockwise direction. In the nozzle 3a and the nozzle 3c, and the nozzle 3b and the nozzle 3d, the radiation directions 9 are opposite to each other. The flow rate of the top blown compressed air was 20.0 Nm ³ / h, and the lance height (distance from the tip of the lance to the stationary liquid surface) was 100 mm.

  In the water model experiment, when the behavior of the liquid surface 13 when the top blowing from the top blowing lance 1 was observed, the occurrence of sloshing (swing) was observed on the liquid surface 13. The movement of the wave on the liquid surface 13 in the sloshing is a movement that is always symmetrical on both sides of the lance center axis with the lance center axis portion as the lowest point in a plane including the lance center axis. When the level of the liquid level reached the maximum in the furnace wall part of a certain plane, the level of the liquid level reached the minimum in the plane of the furnace wall part perpendicular to the plane including the lance central axis. . In the planes orthogonal to each other, when one of the liquid levels rises, the other is lowered periodically so as to synchronize with it. Moreover, when the occurrence state of the splash was confirmed, it was also confirmed that the splash generated from the hot spot 14 becomes significant when the sloshing wave returns from the furnace wall toward the furnace center. It is also confirmed that when the four-hole lance 2 is rotated around the lance center axis 5 to change the nozzle radiation direction, the sloshing movement direction is also rotated, and the sloshing wave movement direction is always related to the nozzle radiation direction. It was.

  From the above observation results in the water model experiment, if the above-described sloshing caused by the top blowing jet of the four-hole lance 2 can be suppressed, the occurrence of splash in refining using the four-hole lance 2 can be suppressed, and the splash from the converter 11 can be suppressed. It was estimated that it was possible to suppress adhesion and metal adhesion. Also, sloshing always moves symmetrically on both sides of the lance center axis in the plane including the lance center axis, and always moves in the opposite direction in the plane perpendicular to the plane including the lance center axis. The possibility that the 90 ° rotational symmetry of the nozzle radial direction 9 promotes the occurrence of sloshing was considered. Therefore, it was decided to evaluate the occurrence of sloshing and the occurrence of splash in the water model experiment when the 90 ° rotational symmetry of the nozzle radial direction 9 is broken.

In the prepared nozzle arrangement of the four-hole lance 2, attention is paid to β ₁ of the spread angle β. And in addition to the normal 4-hole lance of β ₁ = 90 ° used in the water model experiment, β ₁ = 95 °, 100 °, 105 °, 110 °, 115 °, 120 °, 125 ° were prepared. The remaining three spread angles were β ₃ = β ₁ and β ₂ = β ₄ = 180 ° −β ₁ . FIG. 1 shows an example of β ₃ = β ₁ = 120 ° and β ₂ = β ₄ = 60 °. All the nozzles 3 are straight nozzles having a nozzle diameter of 2.5 mm, and the inclination angle α is 20 °. The other experimental conditions were such that the top blown compressed air flow rate was 20.0 Nm ³ / h and the lance height was 100 mm.

First, the sloshing generation behavior of the bath surface was compared. When a normal four-hole lance 2 with β ₁ = 90 ° was used, as described above, large sloshing occurred in the four directions associated with the radial direction 9 of the nozzle 3. On the other hand, in the experiment using the nozzle 3 having a spread angle β ₁ of 95 ° to 120 °, it was confirmed that sloshing was significantly suppressed as compared with the case of β ₁ = 90 °.

On the other hand, the sloshing of the lance with the spread angle β ₁ = 125 ° was larger than that of the 4-hole lance 2 with β ₁ = 90 °. In this case, β ₂ = β ₄ = 55 °, the fire point positions by the adjacent nozzles b and c, and the fire point positions by the nozzles d and a are too close to each other, and the liquid level 13 at these two fire point positions. It can be inferred that the dents of the joints resulted in increased sloshing.

Next, in the same water model experiment, the above-described four-hole lance 2 is used for top blowing, a water absorbent cloth is installed at a position 300 mm above the water bath surface, and the amount of water absorbed by the water absorbent cloth is evaluated. The occurrence of the splash that was reached was evaluated. Table 1 shows the results of measuring the amount of water (the amount of splash reaching the water-absorbing cloth) collected on the water-absorbing cloth by continuing to blow up for 1 minute. When the 4-hole lance 2 of β ₁ = 90 ° is used (lance No. 1), the collected amount is set to 1.0, and the collected amount of the other 4-hole lance 2 is β ₁ = 90. Table 1 shows the values divided by the collected amount of °.

As is clear from the results shown in Table 1, when using a 4-hole lance 2 with β ₁ = 95 ° to 120 ° (lance Nos. 2 to 7), it is compared with a 4-hole lance 2 with β ₁ = 90 °. The amount of water collected (splash amount) is reduced by 0.5 to 0.7 times, and the effect of reducing the amount of splash generation is clear. Compared with the observation result of the sloshing occurrence state, the sloshing generation amount is reduced in the 4-hole lance 2 with β ₁ = 95 ° to 120 ° as compared with the 4-hole lance 2 with β ₁ = 90 °, and the sloshing is caused by the sloshing. It is presumed that the splash generated by the collision between the wave and the top blowing jet was suppressed.

From the results of the water model experiment described above, regarding the nozzle arrangement of the four-hole lance 2, the spread angle β, which is the angle between the radial directions 9 of the adjacent nozzles 3 around the lance center point 7, is the same as in the past. If β ₁ = β ₂ = β ₃ = β ₄ = 90 °, splashing occurs near the fire point due to top blowing, whereas the four divergence angles β formed by the four-hole nozzles With respect to the two spread angles facing the center point, it is expected that the occurrence of splash can be suppressed by setting the spread angle to 95 ° to 120 °.

Note that β ₁ = β ₃ = 95 ° to 120 ° is β ₂ = β ₄ = 180 ° −β ₁ , and therefore β ₂ = β ₄ = 85 ° to 60 °. Adjacent to the divergence angle β ₁ are the divergence angle β ₂ and the divergence angle β _4, that is, when the adjacent divergence angles β around the lance center point 7 are not equal, it can be said that the occurrence of splash is reduced. .

  Then, decarburization blowing smelting experiment of dephosphorizing hot metal using a test converter was conducted. With dephosphorizing hot metal, hot metal discharged from the blast furnace (P content is around 0.1% by mass) is dephosphorized to a P content of about 0.02% by mass, while decarburizing is performed. It refers to hot metal having a C content of around 3.7% by mass.

An experiment was conducted by charging 2.0 t of dephosphorized hot metal into a test converter and blowing oxygen over the hot metal for 10 minutes from an upper blowing lance 1 installed at 400 mm above the hot metal bath surface at 480 Nm ³ / h. The top blow lance 1 is a four-hole lance 2 in which four straight nozzles are arranged as nozzles 3 around the center axis 5 of the lance, the diameter of the straight nozzle is 9.0 mm, and the inclination angle α is 20 °. Were all the same. Seven four-hole lances 2 having different spread angles β ₁ of 90 °, 95 °, 100 °, 105 °, 110 °, 115 °, 120 °, and 125 ° were prepared. The remaining three spread angles were β ₃ = β ₁ and β ₂ = β ₄ = 180 ° −β ₁ .

  In order to remove the influence of slag, blowing is performed without adding auxiliary raw materials such as quick lime, and a part of the exhaust gas is sampled from the flue toward the dust collector and dust is collected with a filter to evaluate the dust generation rate. It was. Moreover, the thickness of the bullion attached to the furnace port was evaluated for the amount of bullion scattering.

Table 2 shows the measurement results of the dust generation rate and the thickness of the attached metal. These measurement results were evaluated based on values obtained by dividing each measurement result by the result of β being 90 ° based on the result of the spread angle β ₁ being 90 °.

The thickness of the attached bare metal was significantly thinner with a lance having a spread angle β ₁ of 95 ° to 120 ° than when β ₁ was 90 °. In the four-hole lance with the divergence angle β ₁ of 95 ° to 120 °, it is considered that sloshing is suppressed and scattering of the metal is also suppressed.

On the other hand, the dust generation rate tended to be reduced in the lance with the spread angle β ₁ of 95 ° to 120 ° as compared to the case of β ₁ of 90 °. In the lance with β ₁ of 95 ° to 120 °, it is considered that as a result of the suppression of spitting, dust generated due to the secondary burst of spitting was reduced.

From the test converter experiment described above, the nozzle arrangement of the four-hole lance 2 is the angle between the radial directions 9 of adjacent nozzles around the lance center point 7 as in the result of the water model experiment described above. With respect to the angle β, if β ₁ = β ₂ = β ₃ = β ₄ = 90 ° as in the prior art, spitting and dust generation increase, whereas four spread angles β formed by the four-hole nozzle 3 Of the two spread angles facing the lance center point 7 (spread angle β ₁ and spread angle β _{3 in the} above experiment), spitting is performed by setting the spread angle to 95 ° to 120 °. And dust generation could be suppressed. The inclination angles α of the four nozzles 3 may be equal or different from each other.

  It can be said that the arrangement of the nozzles 3 of the four-hole upper blowing lance 1 reduces the occurrence of splash when adjacent spread angles β around the lance center point 7 are not equal. It is preferable that the angle difference between adjacent spread angles β is 10 ° or more. More preferably, it is 20 ° or more.

  In the four-hole lance 2 of the present invention, when the inclination angles α of the four nozzles 3 are equal, the positions of the four nozzle center points 8 on the lance tip surface 4 are the same with the lance center point 7 as the center point. It can be arranged on the circumference. When such an arrangement is selected, a four-hole nozzle arranged on the same circumference of the lance tip surface 4 is used to perform high-speed blowing while suppressing splash in the top-bottom blowing converter type refining vessel. In the upper blow lance 1 for a converter having 3, the nozzles 3 viewed on the lance tip surface 4 perpendicular to the lance center axis 5 are arranged at non-equal intervals on the same circumference.

  In the present invention, preferably, the sum of two spread angles β adjacent around the lance center point 7 is 180 °. With this arrangement, the angle between the radial directions 9 of the two nozzles 3 facing in opposite directions around the lance center point 7 is 180 °. In this case, since the horizontal force exerted on the upper blowing lance 1 is offset by the injection from the two nozzles 3 facing each other, it is possible to prevent an excessive force from being applied to the upper blowing lance 1, which is preferable. At this time, the nozzle center is arranged on the lance tip surface 4 in line symmetry with a straight line passing through the lance center point 7 as an axis of symmetry.

  The nozzle inclination angle α of the four holes of the present invention is desirably 10 ° or more and less than 25 °. When the inclination angle α is less than 10 °, the oxygen jets ejected from the four-hole nozzles 3 interfere with each other and are easily merged. Therefore, the inclination angle α is preferably 10 ° or more. On the other hand, if the inclination angle α exceeds 25 °, the oxygen jet approaches the furnace wall and increases the melting rate of the furnace wall refractory, which is not preferable.

  In the present invention, an arrangement in which the nozzle center axis 6 intersects the lance center axis 5 can be preferably used. In the example shown in FIG. 1, the four-hole nozzles 3 all have the same inclination angle α, and the nozzle center axes 6 of the four-hole nozzles 3 all intersect the lance center axis 5 at the same intersection point 10. The nozzle center axis 6 of each of the four nozzles 3 may intersect the lance center axis 5 at different positions. Further, an arrangement in which the nozzle center axis 6 does not intersect the lance center axis 5 may be used, and a so-called twist lance may be used.

In the top blowing lance 1 of the present invention, in addition to the four-hole nozzle 3 around the lance center axis 5, another nozzle may be provided near the lance center axis 5. By disposing one nozzle having a smaller inner diameter than the four-hole nozzle 3 on the lance center shaft 5 and having no inclination angle, it is possible to prevent adhesion of the metal to the tip of the lance.

When performing decarburization blowing of hot metal in a converter-type refining furnace (converter 11), by using the above-described converter blowing upper blow lance 1 (four-hole lance 2) of the present invention as the upper blow lance 1 Moreover, spitting from the converter and adhesion of metal can be suppressed, and dust generation can also be suppressed. The effect is particularly remarkable in high-speed blowing with a high oxygen supply rate. For example, in high-speed blowing where the amount of oxygen supplied per ton of molten steel is 200 Nm ³ / h · ton or more, spitting and metal adhesion are significant in the conventional four-hole lance 2. By using the 4-hole lance 2, it is possible to greatly suppress spitting and metal adhesion.

When performing decarburization blowing of dephosphorized hot metal in the top bottom blowing converter (converter 11) of 300 t / heat, the effect was confirmed using the top blowing lance 1 for converter blowing. A total of 290 to 300 tons of dephosphorized hot metal (C content: 3.7% by mass, P content: about 0.02% by mass) and scrap are charged into a converter, and 3 flocculent lime with a maximum particle size of 30 mm is added. After adding 0.0 to 4.0 t, lump meteorite with a maximum particle size of 30 mm, 0.8 to 1.2 t, MgO brick waste 0.2 to 0.3 t, and iron ore 1.5 to 2.0 t, Decarburization blowing was performed by blowing oxygen to the hot metal at an upper blowing lance 1 to 60000 Nm ³ / h installed approximately 3000 mm above the liquid level 13, and the C content in the steel after decarburization blowing was 0.04 mass The blowing time was adjusted to be%.

The top blow lance 1 is a four-hole lance 2 in which four Laval nozzles are arranged as nozzles 3 around the lance center axis 5, the diameter of the Laval nozzle is 59.0 mm, and the inclination angle α is 20 °, which are all the same. As a condition, all the nozzle center axes 6 of the four-hole nozzles 3 intersect the lance center axis 5 at the same intersection point 10. Under the different conditions of the divergence angle β ₁ , the remaining three divergence angles were β ₃ = β ₁ and β ₂ = β ₄ = 180 ° −β ₁ . Using these four-hole lances 2, decarburization blowing operation was carried out, and the average iron yield of 300 ch meeting the above conditions was evaluated. The iron yield was determined from the mass ratio of iron in the molten steel in the ladle after blowing to the hot metal and scrap iron charged into the furnace before blowing.

(Comparative Example 1)
When a 4-hole lance 2 with divergence angles β ₁ and β ₃ of 90 ° is used, β ₁ = β ₂ = β ₃ = β ₄ = 90 °, and the occurrence of splash during blowing is large, and spitting is Frequent outflow from the furnace mouth to the outside of the furnace was observed. An average iron yield (%) of 300 Ch in the case of using a 4-hole lance 2 having a spread angle β ₁ of 90 ° was calculated and compared with other conditions using this as a reference.

(Comparative Example 2)
When a 4-hole lance 2 with divergence angles β ₁ and β ₃ of 130 ° is used, β ₂ = β ₄ = 50 °, and the scale of splashing during blowing is large, and spitting goes from the furnace port to the outside of the furnace. There were signs of frequent spills. As a result of calculating the average iron yield (%) of 300 Ch when using the 4-hole lance 2 having a spread angle β ₁ of 130 °, the average when using the 90-degree 4-hole lance 2 described in Comparative Example 1 was used. It was 0.02% lower than the iron yield (%).

Example 1
When a 4-hole lance 2 with divergence angles β ₁ and β ₃ of 100 ° is used, β ₂ = β ₄ = 80 °, so that the occurrence of splash during blowing is small, and spitting from the furnace port to the outside of the furnace The frequency of outflow decreased compared to Comparative Example 1 and Comparative Example 2. As a result of calculating the average iron yield (%) of 300 Ch when using the 4-hole lance 2 having the spread angles β ₁ and β ₃ of 100 °, the 4-hole lance 2 of 90 ° described in Comparative Example 1 was used. The average iron yield (%) in the case increased by 0.15%.

DESCRIPTION OF SYMBOLS 1 Top blow lance 2 4 hole lance 3 Nozzle 4 Lance tip surface 5 Lance center axis 6 Nozzle center axis 7 Lance center point 8 Nozzle center point 9 Radial direction 10 Intersection 11 Converter 12 Molten metal 13 Liquid surface 14 Fire point

Claims (3)

In the top blowing lance for converter blowing, which has nozzles of 4 holes in total around the lance central axis,
The four-hole nozzle has an angle of the nozzle center axis with respect to the lance center axis (inclination angle α) of 10 ° or more,
The intersection of the plane of the lance tip perpendicular to the lance center axis (hereinafter referred to as “lance tip surface”), the lance center axis, and the nozzle center axis is defined as the lance center point and nozzle center point, respectively. The direction from the nozzle to the nozzle center point is the radial direction, and the angle between the radial directions of adjacent nozzles around the lance center point is the spread angle,
The 4 of the four spread angle formed by the nozzle holes, the two spread angles opposite to the lance center point, the converter blowing the divergence angle is equal to or is less than 120 ° 95 ° or more Top blow lance for smelting.   The top blowing lance for converter blowing according to claim 1, wherein the sum of two spread angles adjacent to each other around the lance center point is 180 °.   When performing decarburization blowing of hot metal in a converter type refining furnace, the top blowing lance for converter blowing according to claim 1 or 2 is used as the top blowing lance. Method.

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