JPH08188816A - Blowing method in converter - Google Patents

Abstract

PURPOSE: To provide a converter blowing method, by which the metallurgical reaction and the operation in the converter can be improved, by using a converter lance nozzle, in which the flowing speed of the jet can widely be changed during blowing. CONSTITUTION: In the converter blowing method using the lance nozzle 1 for converter blowing, having two systems of oxygen line, an oxygen jetting hole 3 at the tip part of one system lance out of two systems is formed as a round shape and the other system 2 is formed into a rectangular shape having >=5 ratio of the long side to the short side or the similar shape and the other one system of the oxygen flowing quantity is in the range of 10-90% of the total oxygen flowing quantity, and the flowing speed is changed during blowing, and the oxygen flowing quantity in the system having the round oxygen jetting hole is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blowing method for an upper blowing converter or an upper bottom blowing converter.

[0002]

2. Description of the Related Art It is well known that when the jet velocity of top-blown oxygen on the surface of molten steel increases, the iron yield loss due to spitting increases, and when the jet velocity decreases, the amount of spitting decreases. Is a fact of. Then, for example, JP-A-57-92123, Japanese Utility Model Publication No. 1-1424.
As disclosed in Japanese Patent Publication No. 41, etc., in order to reduce the oxygen jet flow velocity on the molten steel surface for the purpose of reducing spitting in the converter, the oxygen jet holes of the blowing lance nozzle are made porous, or Measures have been taken to increase the height of the oxygen blowing lance nozzle.

However, when the oxygen ejection holes of the blowing lance nozzle are made porous, the holes are arranged in a limited area at the tip of the lance nozzle, coalescing of the oxygen jets occurs, and the oxygen jet velocity at the molten steel surface. And increase spitting instead. In addition, the cooling structure of the tip of the lance becomes complicated, resulting in insufficient cooling. Further, the rise of the height of the lance nozzle is forced to be selected in a narrow degree of freedom because of adhesion of metal to the nozzle and melting damage of the converter refractory due to gas impact. Also, by the above method,
Even if the oxygen jet velocity on the molten steel surface decreases, the decarboxylation efficiency decreases at the end of blowing, and oxygen in steel and oxygen in slag increase, resulting in deterioration of yield, quality, etc. It has drawbacks.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks and has a simple structure as compared with a porous lance nozzle, and a low oxygen flow rate can be obtained in a state where the height of the lance nozzle is relatively low. In the final stage of blowing, which requires a high oxygen flow rate to improve the efficiency of decarboxylation, a converter using a lance nozzle that can maintain a high oxygen flow rate by increasing the flow rate of one of the two oxygen lines. The purpose is to provide a blowing method.

That is, while the total oxygen flow rate and the distance from the nozzle tip to the target object are constant, the gas flow velocity can be changed during gas ejection, and the total oxygen flow rate and the distance from the nozzle tip to the target object can be changed. It is intended to provide a converter blowing method using a lance nozzle, which can change a gas flow velocity larger than ever before in combination with a change.

[0006]

The gist of the first invention for achieving the above-mentioned object is to provide a converter blowing method using a converter blowing lance nozzle having two oxygen lines. The oxygen flow rate of one of the two systems changes within the range of 10 to 90% of the total oxygen supply amount, and the oxygen flow rate of the other one system changes within the range of 90 to 10% of the total acid supply amount during blowing. In this method, the amount of oxygen fed in the system having less oxygen ejection holes is increased, and the blowing method of the converter is characterized in that.

Further, the gist of the second invention for achieving the above object is that in a converter blowing method using a converter blowing lance nozzle having two lines of oxygen lines, Of these, one system has a circular oxygen ejection hole at the tip of the lance, and the other system has a rectangular shape with a ratio of the long side to the short side of 5 or more, or a similar form, and the oxygen flow rate of one system is set to the total oxygen transfer amount. In the range of 10 to 90%, the oxygen flow rate of the other system is changed during the blowing in the range of 90 to 10% of the total oxygen supply amount, and the oxygen flow rate of the system having a circular oxygen ejection hole is changed during the blowing. It is a converter blowing method characterized by increasing the number.

[0008]

FIG. 1 shows an example of the oxygen ejection surface of the oxygen lance nozzle for converter blowing according to the present invention. In FIG. 1, 1 is a lance nozzle body, and 2 and 3 are oxygen ejection holes. A few oxygens are provided by another system,
Independent flow control is possible. Here, 2, 3
These oxygen systems will be referred to as system 1 and system 2, respectively.

FIG. 2 shows another example of the oxygen ejection surface of the oxygen lance nozzle for blowing the converter according to the present invention. In FIG. 2, the oxygen ejection holes 2 (system 1) are ejection holes after ejection, such as strip-shaped ejection holes, which have large damping, and the oxygen ejection holes 3 (system 2) are ejection after ejection such as circular ejection holes. It is an ejection hole with small damping. During the early and middle stages of blowing, the decarbonation efficiency is high at almost 100% regardless of the stirring force of the top-blown oxygen, and the amount of bubble burst type dust is large, because the C concentration in the molten iron is high. is there.
At this time, the converter blowing should be directed to soft blow (blown by low oxygen jet velocity on the molten iron surface) to increase the oxygen flow rate of system 1 and decrease the oxygen flow rate of system 2. The system 1 is mainly used for blowing.

On the contrary, in the final stage of blowing, the decarbonization efficiency is in a region where it decreases, so that a hard blow (blowing by a high oxygen jet velocity on the molten iron surface) is aimed at to secure the decarbonization efficiency. The oxygen flow rate of the system 1 is decreased, the oxygen flow rate of the system 2 is increased, and the system 2 mainly performs blowing. By appropriately controlling the oxygen flow rate of each of the above two systems according to each timing of blowing, by combining it with the control of the lance height (the height from the molten iron to the tip of the lance) that has been conventionally performed, molten iron can be obtained. It is possible to control the oxygen jet velocity on the molten metal surface in a wider range than before.

Further, the oxygen flow rate of each system is set to 10
The reason for defining 90% to 90% is that there is a possibility that the metal from the molten steel may enter into the oxygen ejection holes of the lance at an oxygen transfer amount of 10% or less of the total oxygen transfer amount. Further, in the second aspect of the invention, the combination of the rectangular and circular oxygen ejection holes is that the jet from the rectangular ejection hole has much greater damping and a smaller jet velocity (soft blow) than the circular jet. This is because

[0012]

[Examples] Table 1 shows an example of the shape of the nozzle tip,
The size, the amount of dust generated, and other conditions are shown. In Example 1, as a result of blowing with a lance nozzle having circular oxygen ejection holes having diameters of 50 mm and 33 mm, respectively,
Compared to normal blowing, the amount of dust generated is 4 kg / t on average
on decreased. Further, in Example 2, as a result of blowing with a lance nozzle having a circular oxygen ejection hole having a diameter of 33 mm and a rectangular oxygen ejection hole having a diameter of 20 mm × 196 mm, the amount of dust generated was larger than that in normal blowing. Average 7kg / ton
Diminished.

The total area of the oxygen ejection holes of the lance nozzle shown in the embodiments is designed to be equal to that of a normal lance nozzle.

[0014]

[Table 1]

[0015]

According to the method of the present invention which uses a converter lance nozzle capable of drastically changing the jet flow velocity during blowing, the range in which the oxygen jet velocity on the molten iron surface can be changed during blowing is further expanded. The metallurgical reaction and operation in the furnace can be significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an oxygen ejection surface of a converter lance nozzle capable of significantly changing the flow velocity of a jet flow during blowing used in Example 1 of the present invention.

FIG. 2 is a diagram showing an example of an oxygen ejection surface of a converter lance nozzle capable of significantly changing the flow velocity of a jet flow during blowing used in Example 2 of the present invention.

[Explanation of symbols]

 1 Lance nozzle body 2, 3 Oxygen ejection holes

Claims (2)

[Claims] 1. A converter blowing method using a converter blowing lance nozzle having two oxygen lines, wherein the oxygen flow rate of one of the two systems is in the range of 10 to 90% of the total oxygen content. , The oxygen flow rate of the other system is 90-10% of the total oxygen amount
The method of blowing a converter is characterized in that the amount of oxygen is increased in a system having a smaller number of oxygen ejection holes to increase the amount of oxygen fed. 2. A converter blowing method using a converter blowing lance nozzle having two lines of oxygen lines, wherein one of two lines has a circular oxygen ejection hole at the tip of the lance and the other one line The ratio of the long side to the short side is a rectangle with a ratio of 5 or more or a similar shape, and the oxygen flow rate of one system is in the range of 10 to 90% of the total oxygen transfer rate, and the oxygen flow rate of the other system is the total oxygen transfer rate. Of 90% to 10% of the same during blowing, and increasing the oxygen flow rate of the system having a circular oxygen ejection hole during blowing.