JPH04147755A - Method for adding active metal to molten copper - Google Patents

Abstract

PURPOSE:To improve the uniform mixing property of an active metal by adding the active metal to the descending flow of molten copper in the upper part of a continuous casting mold. CONSTITUTION:While the molten copper 2 is tapped from a melting furnace 1 to a runner 3 a pure Mg rod 7 is fed from the inside of a stopper 4 positioned on the extreme downstream of the runner 3, i.e., the stopper 4 of a molten copper inflow hole 6 to the continuous casting mold 5 to add the Mg to the molten copper. The Mg of the active metal is eventually added to the descending flow 8 of the molten copper in the upper part of the continuous casting mold 5 in this way. The added Mg rides on the descending flow 8 of the molten copper and flows down together with the molten copper in a nozzle 10 while melting in the molten copper and flows into the continuous casting mold 5 where the Mg solidifies as the Mg-contg. copper alloy. A slab 9 is thus formed.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for adding active metals to molten copper, and in particular, when casting active metal-containing copper by a semi-continuous casting method or a continuous casting method. This invention relates to a method for adding active metals to molten copper.

(Prior Art) Copper has good electrical conductivity and thermal conductivity, and is widely used as a basic material in the electronics field, such as lead frame materials, terminal materials, and connector materials. In recent years, LSI
Due to demands for higher density and lighter electrical components, higher strength and higher electrical conductivity are required, and Mg,
Active metals such as Zr, Cr, Ti, CaSi, and Ce have come to be added as alloying elements.

Conventionally, active metals have been added by a method of directly adding active metals into molten copper melted and held in a melting furnace (in-furnace direct addition method). However, in this method, atmospheric oxidation of the active metal occurs during addition and discharge from the melting furnace, and since the molten copper is held in the melting furnace for nearly an hour, the active metal may volatilize during that time. Additionally, there are a number of problems associated with reactions between the active metal and the refractories of the melting furnace.

In recent years, as a solution to the above problems, Japanese Patent Application Laid-Open No. 61878
As disclosed in Publication No. 31, a method of adding active metal by filling a copper or copper alloy tubular body with active metal powder and feeding it into molten steel (filling temperature addition method) has been developed and implemented. .

(Problem to be solved by the invention) The filling temperature addition method described above is also used in the iron industry as a method for adding active metals such as Ca, and there are operational issues such as the wall thickness of the tubular body and the feeding speed of the tubular body. However, it can be said that it is an effective method for preventing atmospheric oxidation of active metals. However, as one can easily imagine, this method has the disadvantage of worsening economic efficiency, making it difficult to use in actual production. Furthermore, there are also problems in that it is difficult to mix the active metal uniformly and that the active metal may volatilize.

On the other hand, with the development of casting technology, the frequency with which copper-based materials are cast by a semi-continuous casting method or a continuous casting method has increased.

The present invention has been made in view of these circumstances, and its purpose is to solve the problems of the conventional methods, and to improve the quality of copper in the casting of active metal-containing copper by semi-continuous casting or continuous casting. When adding active metals to molten metal, it is possible to prevent problems such as atmospheric oxidation, volatilization, and reaction with refractories of active metals without causing a deterioration in economic efficiency, and to improve uniform mixing of active metals. Addition of active metal to molten copper 1]
[This is intended to provide one method.

(Means for Solving the Problems) In order to achieve the above objects, the present invention provides a method for adding an active metal to molten copper having the following configuration. That is, in the method of adding active metals to molten copper according to the present invention, when active metal-containing copper is cast by a semi-continuous casting method or a continuous casting method, the copper is tapped from a melting furnace and continuously cast through a runner or tundish. Mg, Zr, Cr, T to the molten copper flowing into the mold
A method of adding active metals such as i, Ca, Si, Ce, etc. to molten copper, characterized in that the active metal is added to a downward flow of molten copper above a continuous casting mold. .

(Function) As described above, in the method of adding active metal to molten copper according to the present invention, the active metal is added to the downward flow of molten copper above the continuous casting mold. Therefore, the added active metal is not melted and mixed into the molten copper, but flows down with the molten copper, flows into the continuous casting Y, and the mixing of the active metal is completely completed before the molten copper solidifies in the continuous casting mold. It can be done.

At this time, the active metal is added to and mixed with the flowing copper molten metal in a downward flow, so it can be mixed well and uniformly dissolved in the copper molten metal. Therefore, the uniform mixing property of the active metal can be improved, and as a result, the active metal Active metal-containing copper with uniform metal concentration can be cast.

In addition, the distance between the downstream part of the molten copper to which the active metal is added and the continuous casting mold is short, and the time during which the active metal exists is also short, causing atmospheric oxidation and volatilization of the active metal. It can be lost. Furthermore, since it is not added to the melting furnace, it naturally does not cause problems such as reactions with the refractories of the melting furnace.

The above-mentioned addition method according to the present invention does not require new equipment such as a tubular body in the case of the conventional filling temperature heating method.
Since it can be implemented, it does not cause deterioration of economic efficiency.

The shape of the active metal to be added is not particularly limited, or it is preferable to sequentially dissolve linear, rod-shaped, and plate-shaped solids as in the examples described later for homogeneous mixing. Therefore, granular,
When using a powdered material, is it preferable to wrap the granular material in a thin plate or to fill a cladding tube with the powdered material?This method is better than the solid method described above. It is also inferior in that it tends to lead to a decline in economic efficiency.

If the active metal is alloyed with copper in advance, for example, into a Cu-Mg alloy, and added as an alloy, the melting point will be lowered, making it easier to melt, and the activity of λ(g, etc.) will also be lowered, reducing evaporation loss. etc., which is preferable to adding an active metal alone.

As mentioned above, the addition method according to the present invention is to add the active metal to the descending flow of molten copper above the continuous casting mold, and an addition method similar to this addition method is disclosed in Japanese Patent Publication No. 7528/1983. However, the two differ in purpose, structure, and effect.

Specifically, Japanese Patent Publication No. 7528/1983 discloses a method and apparatus for mixing powdery desulfurization and dephosphorizing agents into molten metal when desulfurizing and dephosphorizing hot metal and molten steel. The gist is that the tip of the molten metal introduction pipe is positioned within the molten metal, the granular additive is added to the downward flow of the molten metal in the molten metal introduction pipe, and the granular additive is uniformly dispersed and mixed within the molten metal held in a pot, etc. This is intended to promote reactions such as desulfurization and dephosphorization.

However, this publication does not contain any description regarding molten copper, and in the case of continuous or semi-continuous casting of copper, additives (active metals) are added to the downward flow of molten copper above the continuous casting mold as in the method according to the present invention. The means of addition is not disclosed.

The method described in this publication requires that a mixed flow that does not involve gas at the lower end be formed by reducing the cross-sectional area of the skeleton flow path at the lower part of the introduction tube. On the other hand, the method according to the present invention does not require such a method, and the existing equipment such as a nozzle that connects the runner or tundish to the continuous casting mold can be used as is.

(Example) Example 1 The situation of continuous casting of active metal-containing copper according to Example 1 is shown in the first example.
As shown in the figure.

First, 7 tons of copper was melted in the melting furnace (1). Next,
As shown in Fig. 1, the molten copper (21) is discharged from the melting furnace fi+ to the runner (3), and the stopper (4) located at the most downstream position of the runner (3), that is, the continuous casting mold (5), is fed. A 9.8 mmΦ pure Mg rod (7) was sent from the stopper (4) of the molten steel flow hole (6) to add Mg (target addition of 1.0 wt%).

In this way, the active metal Mg is added to the descending flow (8) of the molten copper above the continuous casting mold (5). In FIG. 1, reference numeral 111 indicates charcoal grains that prevent oxidation of the molten steel by blocking it from the atmosphere.

The added ht8 rides on the downward flow of copper molten metal (8),
After dissolving in the molten copper, it flows down the nozzle GOt together with the molten copper, flows into the continuous casting mold (5), solidifies as a Mg-containing copper alloy in the continuous casting mold (5), and forms a so-called slab (9). Form. This slab (9) was continuously pulled out downward and had a thickness of 140 mm, a width of 800 mm, and a length of 3800 m.
A copper alloy slab containing vg of m was obtained.

For the thus obtained slab, analytical test pieces were taken from nine locations in the width direction, including the left end, center, and right end of the top, center, and bottom ends, and the Mg content was analyzed. . As a result, as shown in Table 1, the addition target value: 1.
Mg content is 0.92-0.96wt for 0wt%
% (average 0.95rt%), and it was confirmed that Mg was added uniformly with an average yield of 95%.

Example 2 Rod-shaped Zr, Cr, Ti, Ca, Si, or Ce was used as the active metal added to the descending flow of molten copper (8). Continuous casting of active metal-containing copper was performed in the same manner as in Example 1 except for this point, and the same analysis was conducted. As a result, as in Example 1, the average was 90 to 9.
It was confirmed that the active metal was added uniformly with a yield of 8%.

Comparative Example 1 A rod-shaped active metal was added to the front part (]) of the runner (3).

Continuous casting was performed in the same manner as in Example 1 except for this point.

When using toughness as the active metal, Mg has a specific gravity of 1.7,
Molten copper has a specific gravity of 8.9, which is extremely light compared to molten copper, so it floats to the top of the molten copper and is not mixed with the molten copper. It reacts with oxygen and oxidizes, and as a result,
The yield of the active metal Mg in the obtained slab was extremely low at about 50%, and the concentration was extremely uneven, resulting in poor quality.

When Zr is used as the active metal, Zr has a specific gravity of 6.8, which is very close to the specific gravity of molten copper, so the degree of floating to the top of the molten copper is reduced, but it still does not mix well with the molten copper. First, the uniform mixing of the active metal (2'') was poor. As a result, the obtained slab had an uneven Zr concentration and was of poor quality.

(Effect of the invention) According to the method of adding active metal to molten copper according to the present invention,
When adding active metals to molten copper when casting active metal-containing copper using a semi-continuous casting method or continuous casting method, it is possible to prevent atmospheric oxidation, volatilization, and reaction of active metals with refractories without causing deterioration of economic efficiency. This makes it possible to prevent the occurrence of defects and improve the uniform mixing of active metals. Therefore, in a highly economical manner, active metal-containing copper that uniformly contains a predetermined amount of the required active metal and has no abnormalities such as entrainment of active metal oxides can be produced using a semi-continuous casting method or a continuous casting method. Stable production becomes possible.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an overview of the continuous casting of active metal-containing copper according to Example 1.

Claims (1)

[Claims] (1) When casting copper containing active metals by the semi-continuous casting method or continuous casting method, Mg, Zr,
A method for adding active metals such as Cr, Ti, Ca, Si, Ce, etc. to molten copper, the method comprising adding the active metal to a downward flow of molten copper above a continuous casting mold. .