JPH10287909A - Top-blown lance for blowing gas into converter and also melting skull stuck to nose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve such problem as to be difficult to stably melt and remove the metal stuck to furnace opening hole part over long time without accompanying the stopping of operation and the erosion of refractory in a converter in the conventional lance. SOLUTION: In the top-blown lance 1 having a Laval-shaped nozzle spouting holes 2a, 2b arranged in the circular direction toward the downward outside at the tip part and jetting gaseous oxygen toward molten metal surface through the nozzle spouting holes 2a, 2b, the outlet opening hole surfaces 4a, 4b of the nozzle spouting holes 2a, 2b are formed as inclined state in the range of >90 deg. to <=120 deg. to the center axes (m), (n) so that the length (11 ) at the center side of the lance becomes larger than the length (12 ) at the outside of the lance in the nozzle spouting holes 2a, 2b. By this constitution, the jetting gaseous oxygen is directed to the downward center side of the top-blown lance 1 and the secondary conbustion ratio is suitably improved, and the promotion of the melting of skull stuck to the nose and also, the restraint of the erosion of refractory in the converter are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a converter blowing and melting furnace slab which is capable of reliably and easily melting and removing metal that adheres to the furnace opening of a converter during blowing, which is a refining process. For upper blowing lance.

[0002]

2. Description of the Related Art In oxygen blowing using a converter, a lance for blowing oxygen is inserted from a furnace opening, and high-purity oxygen gas is supplied from the lance to the surface of a molten iron bath accommodated in the converter at a sonic velocity. This is done by blowing at speed. In such oxygen blowing, part of the molten iron is blown upward by high-speed oxygen gas spraying onto the surface of the molten iron bath, and is rapidly cooled and solidified by contact with outside air in the vicinity of the furnace port, thereby solidifying the furnace port. Adheres to

[0003] The metal adhered to and solidified in the furnace port in this way hinders operations such as the inability to insert scrap due to blockage of the furnace port, and is one of the factors that significantly reduce converter productivity. On the other hand, a part of the molten iron blown off in this way also collides with the lance inserted and arranged in the converter, which is one of the causes of melting the nozzle and shortening the lance life.

[0004] In particular, ingots adhering to the furnace opening have been removed by temporarily interrupting the operation and cutting oxygen gas. Such a slab removal operation is an operation called "furnace slab cutting", and has been performed by manual operation of a cutter when it is judged visually that the operation is hindered. For this reason, this “furnace slab cutting” has become a major factor in the decline in productivity in the refining process.
Conventionally, various inventions have been proposed to reduce "hearth metal cutting". For example, in Japanese Patent Application Laid-Open No. 1-136923, an annular metal plate is attached to the outside of the lance tip, and oxygen gas blown out in a substantially horizontal direction through the annular metal plate is directly supplied to a furnace port attachment metal. Japanese Patent Application Laid-Open No. 4-88110 discloses that the oxygen gas flow path has a spiral groove outside the tip of the lance and is rotated by the oxygen gas flow so that the oxygen gas is substantially horizontal. Japanese Patent Publication No. 3-77248 discloses an invention that installs a wind turbine that blows out in the direction, and dissolves and removes the metal attached to the furnace port using oxygen gas that is evenly injected in a horizontal 360-degree direction from this wind turbine. A sub-nozzle discharge hole for promoting secondary combustion is provided independently of the flow path from the main nozzle discharge hole, and a gas flow resistor is disposed in the sub-nozzle discharge hole, so that oxygen gas from the sub-nozzle discharge hole is provided. Suitable for promoting secondary combustion Japanese Patent Application Laid-Open No. 4-308020 discloses an invention in which the secondary combustion rate is improved as a subsonic speed, and the metal that is attached to the furnace opening is dissolved and removed by the increased heat.
Using a lance having a plurality of Laval-shaped furnace port attached metal ingot melting nozzles that are downwardly oriented at 30 ° and radially arranged,
Japanese Patent Application Laid-Open No. 61-143507 discloses a non-circular shape in which the ratio between the major axis and the minor axis is 1.2 or more. Japanese Patent Application Laid-Open No. Hei 8-232010 discloses an invention in which a lance having an opening shape and having a plurality of nozzle discharge holes having the same shape is used to promote secondary combustion to dissolve and remove a metal attached to a furnace port. In the publication, a curvature of R is provided in the entire area of 180 ° or 360 ° outside the lance of the nozzle discharge hole,
A flow is created in the direction of 90 ° with the surface of the molten metal bath.
Inventions have been proposed in which a lance that promotes the next combustion is used to dissolve and remove metal from the furnace port.

[0005]

However, Japanese Patent Application Laid-Open No. Hei.
In the inventions proposed in JP-A-136923, JP-A-4-88110, or JP-A-4-308020, a lance exclusively used for melting metal is used. You have to stop. For this reason, the converter operation pitch is reduced, and a decrease in productivity is inevitable.

According to the invention proposed in Japanese Patent Publication No. 3-77248, although it is possible to dissolve the metal attached to the furnace port during blowing, oxygen is contained in the refractory of the converter together with the metal attached to the furnace port. Since the gas is inevitably injected, the refractory is melted and the life of the converter is shortened.

In the invention proposed in Japanese Patent Application Laid-Open No. 61-143507, although the secondary combustion is promoted, the promotion of the secondary combustion rather causes the melting of the converter refractory and shortens the life of the converter. Let me do it.

According to the invention proposed in Japanese Patent Application Laid-Open No. Hei 8-232010, it is certain that both the promotion of melting of the metal at the furnace opening and the suppression of the melting of the refractory in the converter due to the increase in the secondary combustion rate. Can be. However, as a result of further study by the present inventors for further improvement, there is a possibility that the jet characteristics may be changed due to deformation or wear of the curvature of the R portion with long-term use. found. Therefore, according to the present invention as well, it is difficult to stably promote the melting of the core metal adhered to the furnace port and the suppression of the melting of the refractory in the converter over a long period of time.

As described above, according to the conventional invention, it is difficult to stably dissolve and remove the metal deposited on the furnace port over a long period of time without causing a primary interruption of operation or melting of the converter refractory. is there.

[0010] Here, an object of the present invention is to develop a technique for improving the productivity of a converter using an upper blowing lance for melting and melting of a converter mouth metal. Furthermore, another object of the present invention is to stably satisfy the conflicting demands of promoting melting of metal at the furnace mouth by secondary combustion and suppressing erosion of converter refractories for a long period of time without increasing production costs. Is to develop technologies that can do that.

[0011]

Means for Solving the Problems The present inventors have disclosed Japanese Patent Application Laid-Open No. Hei 6-57320 (Japanese Patent Application No.
No. 90915) focused on a low spitting type upper blowing lance for molten metal refining. According to this low-spitting lance, although the effect of reducing the amount of metal attached to the furnace opening can be obtained, it is difficult to completely eliminate it.

Therefore, the inventors of the present invention have proposed that 2
By controlling the next combustion to the optimum degree from the viewpoint of both melting of the metal at the furnace mouth and suppression of melting of the refractory of the converter, it is thought that the above-mentioned object can be achieved. The characteristics of the jet of oxygen gas ejected from the jet were studied in detail.

In the conventional lance, in order to form a supersonic jet jet, the center axis of a plurality of nozzle discharge holes arranged outward and downward from the lance has a vertical positional relationship with the outlet opening surface. Unlike the lance, the exit opening surface of the nozzle discharge hole is the central axis (the center of the oxygen gas jet)
The jet characteristics (especially the jet direction) of oxygen gas were examined for the lance formed obliquely with respect to.

As a result, by appropriately setting the direction in which the inclined surface is formed, the jet characteristic changes toward the central side below the lance unlike the conventional jet characteristic toward the lance downward and outward, which is the extension direction of the nozzle discharge hole. Due to this change in the jet characteristics, the secondary combustion in the converter is optimized from the viewpoint of both melting of the slab metal adhered to the furnace mouth and suppression of erosion of the refractory of the converter, thereby melting the metal sunk to the furnace mouth. The inventors of the present invention have found that it is possible to perform converter blowing while suppressing the converter refractory erosion and achieve the above-mentioned object, and thus completed the present invention.

Here, the gist of the present invention is that a tip has a plurality of nozzle discharge holes circumferentially arranged downward and outward, and oxygen gas is supplied to the molten metal bath surface through the nozzle discharge holes. In the upper blowing lance for blowing the converter and melting the furnace mouth metal, the outlet opening surface of at least one nozzle discharge hole is used to prevent the oxygen gas to be blown out from the converter blowing and melting the furnace metal. An upper-blowing lance for converter blowing and furnace port metal melting, characterized in that it is formed to be inclined with respect to the central axis of the nozzle discharge hole so as to head toward the lower center side of the blowing lance.

According to the preferred embodiment of the present invention, when the outlet opening surface of the nozzle discharge hole has a Laval shape, the length of the nozzle discharge hole on the lance center portion side is equal to that of the nozzle discharge hole. When the nozzle discharge hole has a straight shape, the outlet opening surface of the nozzle discharge hole is formed so as to be larger than 90 ° and not more than 120 ° with respect to the central axis so as to be longer than the outer length of the lance. However, the nozzle discharge hole may be formed so as to be inclined in a range of 60 ° or more and less than 90 ° with respect to the central axis so that the length of the lance center portion side of the nozzle discharge hole is smaller than the length of the lance outside side.

In other words, in this preferred embodiment, the outlet opening surface of the Laval-shaped nozzle discharge hole is inclined downward and outward so as to satisfy the above range, so that the straight-shaped nozzle discharge hole is formed. Is to incline the outlet opening surface toward the center side below the lance so as to satisfy the above range.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an upper-blowing lance for converter blowing and melting of slab metal according to the present invention will be described more specifically with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing a tip portion of an upper blowing lance 1 for converter blowing and melting of a furnace mouth metal in the present embodiment. FIG. 1 (a) is a front view, and FIG. 1 (b) is a sectional view.

At the tip of the lance 1 of the present embodiment, nozzle discharge holes 2a, 2b, 3a, 3b are arranged circumferentially downward and outward. The nozzle discharge holes 2a, 2b are provided at the outlet opening surfaces 4a, 4b.
The nozzle discharge holes 3a and 3b have outlet opening surfaces 5a and 3b, respectively.
Straight shape with constant inner diameter up to 5b.

Oxygen gas is supplied to the tip of the lance 1 from an oxygen supply device (not shown), and through the nozzle discharge holes 2a to 3b, as indicated by white arrows in FIG. It is ejected toward the surface of the molten metal (not shown) accommodated in front of 2a to 3b.

In the present embodiment, the outlet opening surfaces 4a, 4b are inclined so that each of the nozzle discharge holes 2a, 2b and the nozzle discharge holes 3a, 3b is inclined at an inclination angle α with respect to the central axis m.
4b, and the outlet opening surfaces 5a and 5b were formed so as to be inclined with an inclination angle α with respect to the central axis n. Exit opening surface
The formation of 4a, 4b, 5a, 5b was performed by appropriately processing the tip of the lance 1.

Here, the set values of the inclination angle α are shown in Table 1.

[0024]

[Table 1]

FIG. 1 (b) illustrates a case where the inclination angle α exceeds 90 °, and a dashed line in FIG. 1 (b) indicates a lance when the inclination angle α is less than 90 °. 1 shows the outer shape of the tip portion.

With respect to the lances 1 of Sample Nos. 1 to 13, the jet characteristics of the oxygen gas when the oxygen gas was jetted, that is, the jet direction (jet flow behavior) of the oxygen gas were examined. When oxygen gas is ejected from the nozzle discharge holes 2a and 2b, the nozzle discharge holes 3a and 3b are plugged and closed, and when oxygen gas is ejected from the nozzle discharge holes 3a and 3b, the nozzle discharge hole 2a is discharged. , 2b were plugged and closed to investigate each nozzle discharge hole shape (Laval or straight).

FIG. 2 schematically shows a method for evaluating the jet characteristics. In FIG. 2, N ₂ gas is blown from the test nozzle 30, the needle 31 is moved outward from the center of the test nozzle 30 by the traverser 32, and the needle 31 is connected to the U-shaped pipe 33 filled with water to simplify the pressure distribution. And the jet characteristics were evaluated.

FIG. 3 shows sample No. 1, sample No. 4 and sample N.
14 is a graph showing the jet characteristics measured for o.7. In the graph shown in the figure, the height: h (mm) is the test nozzle 30
The distance from the center means the pressure index, and the pressure index means the relative pressure value. In the graph shown in FIG.
o.1 indicates a sample No.4, and a triangle indicates a sample No.7.

In the graph shown in FIG. 3, the fact that each measured value is directed to the left indicates that the oxygen gas ejected from the nozzle discharge hole is bent toward the lower center side of the lance and ejected.

From the graph shown in FIG. 3, when compared with the conventional lance of sample No. 1 (marked by ●), the lance of sample No. 4 (marked by Δ)
The direction of the jet of oxygen gas is changed to the lower outside of the lance,
It can be seen that the lance (▲) of sample No. 7 is changed to the lower inner side of the lance. That is, the outlet opening surfaces 4a, 4b of the Laval-shaped nozzle discharge holes 2a, 2b are connected to the nozzle discharge holes 2a, 2b.
When the inclined surface is directed to the lower center side of the lance 1 (sample No. 2 to sample no.
In 4), the oxygen gas is jetted downward and outward of the lance 1. When the inclined surface is directed downward and outward of the lance 1 (sample Nos. 5 to 7), the oxygen gas is discharged from the lance 1. It jets toward the lower center side.

On the other hand, with the straight lances 1 of Sample Nos. 8 to 13, the opposite result was obtained. That is, the outlet opening surfaces 5a, 5 of the nozzle discharge holes 3a, 3b
Assuming that b is an inclined surface with respect to the central axis n of the nozzle discharge holes 3a and 3b, if the inclined surface is directed toward the lower center side of the lance 1 (sample No. 8 to sample No. 10), the oxygen gas is In the case where the inclined surface is directed toward the lower center side of the lance 1 and directed downward and outside the lance 1 (sample Nos. 11 to 13), the oxygen gas is jetted toward the lower outer side of the lance 1 .

As described above, the outlet opening surfaces 4a and 4b of the nozzle discharge holes 2a and 2b are inclined with respect to the center axis m, or the outlet opening surfaces 5a and 5b of the nozzle discharge holes 3a and 3b are set with respect to the center axis n. The reason why the inclined plane changes the jet direction of the oxygen gas will be described with reference to FIGS. 4 and 5.

[0033] Figure 4, the jet direction of the oxygen gas ejected from the nozzle discharge hole is, the relationship between the outlet pressure P ₂ and the inner pressure P _a of the nozzle discharge hole, illustration why bent schematically showing a is, FIG. 4 (a) shows the case where P _2> P _a, FIG. 4 (b) shows a case of P ₂ <P _a.

[0034] FIG. 4 (a), the as shown in FIG. 4 (b), oxygen gas, in the case of P _2> P _a bent short side wall surface of the nozzle discharge hole, in the case of P ₂ <P _a Is bent toward the long wall surface side of the nozzle discharge hole. This corresponds to the outlet pressure P of the nozzle discharge hole.
₂ is an oxygen gas ejected from the short side if higher than the furnace pressure P _a inflated immediately, whereas short side if the outlet pressure P ₂ of the nozzle discharge hole is less than the furnace pressure P _a It is considered that the oxygen gas ejected from is a phenomenon caused by contraction.

FIG. 5 is an explanatory view schematically showing the jetting direction of oxygen gas ejected from the nozzle discharge hole of the lance 1. FIG. 5 (a) shows the sample No. 1 and FIG. b) is sample N
o.4 and Fig. 5 (c) shows sample No.7. 5 (d) shows sample No. 1 ', FIG. 5 (e) shows sample No. 8, and FIG.
No.11 is shown.

In the present embodiment, as shown in FIG.
Is the case of the outlet pressure P ₂ <furnace pressure P _a of the nozzle discharge hole, the oxygen gas from the nozzle discharge hole of a jet characteristics as described below.

That is, as shown in FIGS. 5 (a) to 5 (c), in the case of the Laval-shaped nozzle discharge holes 2a, 2b, the passing oxygen gas passes through the nozzle discharge holes 2a, 2b. As the pressure decreases, it expands. When oxygen gas is jetted from the outlet opening surface 4a, the nozzle discharge hole 2
The oxygen gas flowing on the shorter inner wall surface of the inner wall surfaces a and 2b (wall surface 7 in FIG. 5 (b) and wall surface 6 in FIG. 5 (c)) flows on the longer wall surface side (FIG. 5 (c)). wall at b) 6,
Since the degree of the pressure drop is smaller than that of the oxygen gas flowing on the wall 7 in FIG. 5C, the flow of the oxygen gas is disturbed, and as a whole, the longer wall (the wall in FIG. 5B) 6, the jet direction is bent to the wall surface 7) in FIG. 5 (c). Therefore, the Laval-shaped nozzle discharge holes 2a, 2b
In this case, oxygen gas is jetted in a direction opposite to the direction in which the outlet opening surface 4a is directed.

On the other hand, as shown in FIGS. 5 (d) to 5 (f),
In the case of the straight nozzle discharge holes 3a and 3b, the flow rate of the passing oxygen gas is the same at any position of the nozzle discharge holes 3a and 3b, and the oxygen gas is jetted from the outlet opening surface 5a. A sudden drop in pressure occurs. For this reason, the oxygen gas flowing on the long wall surface side (wall surface 8 in FIG. 5 (e), wall surface 9 in FIG. 5 (f)) loses the oxygen gas flowing on the short wall surface side (wall surface 9 in FIG. 5 (e)). , FIG.
Since the pressure drop is smaller than that of the oxygen gas flowing through the wall 8) in (f), turbulence occurs in the oxygen gas jet, and as a whole, the shorter wall surface (the wall in FIG. 5 (e)) 9, the jet direction is bent to the wall surface 8) in FIG. 5 (f). Therefore, the straight nozzle discharge holes 3a, 3
In the case of b, the oxygen gas is jetted in the same direction as the direction in which the outlet opening surface 5a is directed.

In the present embodiment, a plurality of circumferentially arranged lances 1 are provided by utilizing the relationship between the inclination of the outlet opening surface of the nozzle discharge hole and the jet direction of the oxygen gas described above in detail. The oxygen gas to be ejected from the nozzle discharge hole in the extension direction is directed to the lower central side of the lance 1. Thereby, the secondary combustion in the furnace is appropriately increased. In other words, an inclined surface which directs the jetted oxygen gas toward the lower center side of the lance is provided on the outlet opening surface of the nozzle discharge hole formed in the lance 1. Therefore, in Table 1 described above, Sample No. 5 to Sample No. 7
Are examples of the present invention in a Laval nozzle discharge hole, and Sample Nos. 8 to 10 are examples of the present invention in a straight nozzle discharge hole.

In sample No. 2 to sample No. 4 or sample No. 11 to sample No. 13, an increase in the secondary combustion rate cannot be expected because oxygen gas is jetted downward and outside the lance 1.

FIG. 6 shows Laval nozzle discharge holes 2a and 2a.
b, the length l ₁ of the nozzle discharge holes 2a, 2b on the lance center side on the outlet opening surfaces 4a, 4b of the nozzle discharge holes 2a, 2b is larger than the length l ₂ on the outside of the lance. FIG. 3 is an explanatory diagram showing a state in which an inclined surface inclined with respect to the center axis m, n is formed, together with changes in the jet characteristics of oxygen gas.

The lance 1 is formed by cutting the tip of a conventional lance having an outer shape shown by a chain line as shown by a solid line.

As shown in the figure, the oxygen gas that has passed through the nozzle discharge holes 2a and 2b is directed toward the lower center side of the lance 1 unlike the conventional jet flow characteristics indicated by the broken line, and the The secondary combustion effect in the converter increases without erosion.

In the present embodiment, the angle α between the outlet opening surfaces 4a, 4b of the Laval-shaped nozzle discharge holes 2a, 2b and the central axis m is desirably in the range of more than 90 ° and 120 ° or less. If the angle α is less than 90 °, the oxygen gas is directed toward the lower outside of the lance 1. On the other hand, if the angle α is more than 120 °, the secondary combustion rate becomes larger than the desired secondary combustion rate, and the refractory erosion may increase. In any case, the secondary combustion may not be able to be controlled appropriately.

The straight nozzle discharge holes 3a, 3
The angle α between the outlet opening surfaces 5a and 5b of b and the central axis n is desirably 60 ° or more and less than 90 ° for the same reason.

FIG. 7 is an explanatory view schematically showing a situation in which the lance 1 attached metal is melted by the secondary combustion inside the converter 10 by the lance 1 of the present embodiment.

The converter 10 contains molten iron 12,
A slag 13 is formed on the surface. The converter 10
A lance 1 is held by a lifting device (both not shown) mounted on a traversing carriage from the furnace port, and is suspended so that the tip is located at a blowing position in the converter 10.

When oxygen gas is jetted from the tip of the lance 1 toward the surface of the molten iron 12, the oxygen gas is bent and jetted toward the lower center side of the lance 1 as shown in FIG. You. For this reason, the secondary combustion effect in the vicinity substantially vertically below the lance 1 increases.

This secondary combustion is represented by the following equation: CO + 1/2 O ₂ = CO ₂ + Q (calorific value).

That is, according to the present embodiment, the amount of heat Q near the center of the converter 10 farthest from the refractory constituting the converter can be increased to promote secondary combustion. The promotion of the secondary combustion is mainly effective for melting the slab metal adhered to the furnace opening, and is not so significant as to melt the converter refractory. In other words, the lance 1 of the present embodiment is a so-called “weak secondary combustion promotion type lance” and does not increase the heating efficiency. It can be done without damage.

At the same time, refining by oxygen blowing can be performed to inject oxygen gas to the molten iron 12 without impairing refining characteristics.

[0052]

EXAMPLES The present invention will be described more specifically with reference to experimental data.

FIG. 8 is an explanatory view showing the tip shape of the lance 21 used in the present embodiment. FIG. 8 (a) is a front view, and FIG.
FIG. 8B is a sectional view taken along the line AA in FIG. Table 2 summarizes the specifications of the lance 21.

[0054]

[Table 2]

As shown in FIG. 8 and Table 2, the lance 21 of this embodiment has an inlet diameter D ₁ : 44 (mm) and an outlet diameter D ₂ : 59.17.
(mm) Spreading Laval nozzle outlets 22a-2a
6 holes are arranged at equal intervals and 2
This is a top blowing lance for converter blowing and furnace mouth metal melting in which a straight central hole 23 of 0 (mm) is arranged.

All of the nozzle discharge holes 22 arranged in a circle
The outlet opening surfaces 22a to 22f of a to 22f are formed as inclined surfaces having an inclination angle α of 100 ° with respect to the central axis m, n.

In this embodiment, the lance 21 is used to
Approximately 1000 charges of oxygen refining were performed in a ton converter.
On the other hand, the lance of the conventional example is exactly the same as the lance 21 shown in FIG. 8 except that the angle between the exit opening surface of the nozzle discharge hole and the central axis is 90 °.

In the lance 21 of the present embodiment, usually 60000 Nm ³ / h
r It is designed so that the outlet pressure of the nozzle discharge holes 22a to 22f becomes the furnace pressure (≒ 1 atm) when acid is supplied. For this reason, the outlet pressure is 1 atm or less with the acid supply amount of the present embodiment. That is, at the outlet, the nozzle discharge holes 22a to 22f
Of the oxygen gas, the oxygen gas that has passed through the shorter inner wall surface expands excessively as compared with the oxygen gas that has passed through the longer inner wall surface. Bend to the center. Therefore,
Inside the converter (i.e., the lower central portion of the lance 21), oxygen gas jetted from each of the six nozzle discharge holes 22a to 22f collides with each other, causing turbulence of the oxygen gas. Combustion occurs, and the metal on the furnace mouth is melted.

FIG. 9 shows the results of oxygen blowing in this embodiment.
11 to FIG. 11 and Tables 3 and 4.

[0060]

[Table 3]

[0061]

[Table 4]

Hereinafter, the results of oxygen blowing will be analyzed with respect to refining characteristics, converter refractory erosion, secondary burning rate, and furnace port metal cutting.

(1) Refining Characteristics FIG. 9 is a graph showing the refining characteristics according to the relationship between the end point [C] and the end point [O] (oxygen concentration in the converter blow-off steel).
0 is a graph showing refining characteristics according to the relationship between the end point [C] and (T-Fe) in slag (total iron in slag), and FIG. 11 shows the blowing time and the amount of dust [Fe] in dust collection water. 7 is a graph showing a relationship with (iron loss in dust in collected dust water).
In addition, the mark ● or Δ indicates the example of the present invention, and the mark ○ indicates the conventional example.

From the graphs shown in FIGS. 9 to 11, it can be seen that there is almost no difference in blowing characteristics between the present invention and the conventional example. It turns out that there is no problem in operation.

(2) Converter refractory erosion Table 3 shows the measurement results of the furnace wall erosion rate (brick erosion rate) at 10 to 40 stages of converter bricks affected by the lance.

From the data shown in Table 3, it can be seen that the furnace wall erosion rate of the example of the present invention does not change at all from that of the conventional example, and that there is no problem in operation even if the lance of the example of the present invention is used.

(3) Secondary Burning Rate and Furnace Metal Cutting Table 4 shows the secondary burning rate and the frequency of furnace metal cutting.

From the data shown in Table 4, the secondary combustion rate is about 1.
You can see that it rises by 5%. This modest increase in the secondary combustion rate enabled efficient melting and removal of the slab metal from the furnace mouth, thus significantly reducing the frequency of furnace slab cutting work to about 1/15. .

Further, as described above, these effects are maintained at about 1000 charges, which indicates that the lance of the present invention has sufficient practical durability.

[0070]

[Modification] In the embodiment described in detail above, all six nozzle discharge holes provided in the lance have an example in which the outlet opening surface is inclined with respect to the center axis. Such a top blowing lance for melting and melting the converter core metal is not limited to only such an embodiment, and also includes an embodiment in which the outlet opening surface of at least one nozzle discharge hole is an inclined surface. You.

Further, in the embodiment, the number of nozzle discharge holes provided to the lance is six except for the center hole. The present invention is not limited to such an embodiment, but includes a lance provided with two or more nozzle ejection holes.

In the embodiment, the case where the nozzle discharge hole has a Laval shape has been mainly described. This is because a Laval-shaped nozzle ejection hole is usually used to set the oxygen gas speed, the amount of acid supply, and the like to predetermined values.
The upper blowing lance for converter blowing and furnace port metal melting according to the present invention is not limited to this embodiment, and the outlet opening surface of the nozzle discharge hole may be appropriately inclined with respect to the central axis. As a result, the jetted oxygen gas is directed to the lower center side of the upper blowing lance for converter blowing and melting of the furnace mouth metal, thereby increasing the secondary burning rate and dissolving and removing the metal sticking to the furnace mouth. Lances are equally included.

Further, in the embodiment, the outlet opening surface of the nozzle discharge hole is a flat inclined surface. However, the upper blowing lance for converter blowing and melting the furnace port base metal according to the present invention has such a configuration. The present invention is not limited to the embodiment, and equally includes a lance having a nozzle discharge hole having an outlet opening surface with a curved inclined surface. In this case, the inclined surface may be either an upwardly convex curved surface or a downwardly convex curved surface, and the above-described inclination angle α or the like is determined by a line connecting the start position and the end position of the curved inclined surface. It is determined.

[0074]

As described above, according to the present invention, the nozzle is discharged with the outlet opening surface of the nozzle discharge hole in the upper blowing lance for converter blowing and melting of the slab metal as an appropriate inclined surface. Despite its extremely simple structure, in which oxygen gas is directed toward the lower center side of the upper blowing lance for blowing and melting the metal at the converter mouth, (1) the furnace, which is a significant impediment to converter productivity Dissolving / removing the sticking metal during blowing, (2)
(3) that the secondary combustion rate can be appropriately improved to such an extent that it does not melt the metal adhered to the furnace opening and does not melt down the converter refractory, (4) Due to the moderately improved secondary combustion rate (weak secondary combustion) in the above item (3), the slab metal adhered to the furnace port is melted during blowing, and the furnace port slab cutting that requires no steelmaking time Time (average 3.
7 min / ch), and the production cost can be reduced.
Further, (5) for a period sufficient for practical use, (1)
The effect of being able to maintain the effects of (4) could be obtained.

The practical significance of the present invention having such an effect is extremely remarkable.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view extracting and showing a tip portion of an upper blowing lance for melting and melting a converter mouth metal in an embodiment.
Is a front view, and FIG. 1 (b) is a cross-sectional view.

FIG. 2 is an explanatory diagram schematically showing an outline of a method for evaluating jet characteristics in the embodiment.

FIG. 3 is a graph showing jet characteristics measured for Sample No. 1, Sample No. 4 and Sample No. 7 in the embodiment.

[4] the jet direction of the oxygen gas ejected from the nozzle discharge hole is, the relationship between the outlet pressure P ₂ and the inner pressure P _a of the nozzle discharge hole, the reason to be bent an explanatory view schematically showing , 4 (a) shows a case of P _2> P _a, FIG. 4 (b) shows a case of P ₂ <P _a.

FIG. 5 is an explanatory view schematically showing a jet direction of oxygen gas ejected from a nozzle discharge hole of a lance in the embodiment. FIG. 5 (a) shows a sample No. 1 and FIG. Is sample No.4
FIG. 5 (c) shows sample No. 7, FIG. 5 (d) shows sample No. 1 ',
FIG. 5E shows sample No. 8, and FIG. 5F shows sample No. 11.

FIG. 6 shows an embodiment in which a lance having a Laval-shaped nozzle discharge hole has a lance center side length l ₁ of the nozzle discharge hole larger than a lance outer side length l ₂ on an outlet opening surface of the nozzle discharge hole. FIG. 9 is an explanatory diagram showing a state in which an inclined surface that is inclined with respect to the central axes m and n is formed so as to be larger, together with a change in the oxygen gas jet characteristics.

FIG. 7 is an explanatory diagram schematically showing a situation in which the metal adhered to the furnace opening is melted by the secondary combustion inside the converter by the lance of the embodiment.

8A and 8B are explanatory views showing the tip shape of the lance used in the embodiment, wherein FIG. 8A is a front view, and FIG. 8B is a sectional view taken along the line AA in FIG. 8A.

FIG. 9 is a graph showing the refining characteristics according to the relationship between the end point [C] and the end point [O] (oxygen concentration in converter blow-off steel) in Examples.

FIG. 10 shows an example in which the end point [C] and the slag (TF
5 is a graph showing refining characteristics in relation to e) (total iron in slag).

FIG. 11 shows the blowing time and the dust in the dust collection water in the embodiment.
4 is a graph showing a relationship with [Fe] content (iron loss in dust in collected dust water).

[Description of sign]

DESCRIPTION OF THE REFERENCE NUMERALS 1 Top blowing lance 2a, 2b Laval nozzle discharge hole 3a, 3b Straight nozzle discharge hole 4a, 4b, 5a, 5b Outlet opening surface 10 Converter according to the present invention 11 Metal at the furnace port 12 Molten iron m, n Central axis α Tilt angle

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Junichi Tani, 3F, Oji, Kashima-shi, Ibaraki Sumitomo Metal Industries, Ltd. Kashima Works, Ltd. In-house (72) Inventor Koji Sato 48, Izaho, Ibaraki-shi, Osaka Tatsumi Industrial Co., Ltd. (72) Inventor Masahiro Ito 48, Sazaho, Ibaraki-shi, Osaka Tatsumi Industrial Co., Ltd.

Claims (2)

[Claims] 1. A converter blower having a plurality of nozzle discharge holes circumferentially arranged downward and outward at a tip thereof, and blowing oxygen gas toward a molten metal bath surface through the nozzle discharge holes. In the furnace mouth metal melting top blowing lance, the outlet opening surface of at least one of the nozzle discharge holes is formed such that the jetted oxygen gas is at the lower center side of the converter blowing and furnace mouth metal melting upper blowing lance. Characterized in that it is formed obliquely with respect to the central axis of the nozzle discharge hole so as to be directed toward the nozzle. 2. When the nozzle discharge hole has a Laval shape, the outlet opening surface is such that the length of the nozzle discharge hole on the center of the lance is larger than the length of the nozzle discharge hole on the outside of the lance. More than 90 ° with respect to the central axis 120
° or less, and when the nozzle discharge hole is straight, the outlet opening surface is such that the lance center portion side length is smaller than the lance outside side length, 2. The semiconductor device according to claim 1, wherein the main body is formed to be inclined at an angle of 60 ° or more and less than 90 ° with respect to the central axis.
The above described blowing lance for converter blowing and furnace mouth metal melting.