JPH06212300A - Manufacture of low oxygen copper containing p by using shaft furnace - Google Patents

Abstract

PURPOSE:To efficiently manufacture low oxygen copper containing P in a series of processes involving the shaft furnace holding furnace (oxidation treatment) continuous transfer by a moving spout casting. CONSTITUTION:Electric copper or pure copper scrap are used as a raw material and melted in a shaft furnace. This molten metal is continuously supplied to a mold 4 through a moving spout. P content is adjusted in the moving runner, and at the same time, low oxygen copper containing P is manufactured by executing deoxidation while blowing inert gas into the molten metal and stirring the molten metal.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing P-containing low-oxygen copper, and more specifically, it contains P in a series of steps including a shaft furnace → holding furnace (oxidation treatment) → continuous transfer by a transfer gutter → casting. The present invention relates to a method for producing low oxygen copper.

[0002]

2. Description of the Related Art Copper-based products are roughly classified into pure copper-based products and copper alloy-based products according to their composition. The pure copper-based products are classified into the following three types according to JIS standard based on oxygen content. Oxygen-free copper: oxygen content of 10 ppm or less P deoxidized copper: oxygen content of 20 to 50 ppm Tough pitch copper: oxygen content of 250 to 350 ppm

Of these, oxygen-free copper has the highest purity and is the best in terms of thermal conductivity and electrical conductivity, but it lacks strength and is problematic in versatility. Therefore, in order to solve the problem of insufficient strength, oxygen-free copper containing a small amount of P is commercially available. That is, P has the function of increasing the strength without significantly changing the thermal and electrical characteristics of oxygen-free copper.

Currently used as a process for producing P-containing oxygen-free copper is a vacuum furnace and an atmosphere (reducing gas such as H ₂ and CO).
This is a method of melting oxygen-free copper using a furnace and adding a necessary amount of P to this, and an oxygen-free copper manufacturing facility is indispensable.

As another method for producing P-containing oxygen-free copper, a method of using the above-mentioned P-deoxidized copper can be considered. However, P-deoxidized copper has a higher oxygen content than oxygen-free copper as described in detail below. (Oxygen amount: 20 to 50 ppm). To make it practical as a P-containing oxygen-free copper, it is necessary to reduce the oxygen amount to 10 ppm level or less.

That is, P deoxidized copper is obtained by melting electrolytic copper ingot or pure copper-based scrap as a raw material in a reducing atmosphere in a shaft furnace and then casting through a holding furnace, if necessary, after the holding furnace. Deoxidation is carried out by adding P at the stage before casting, but the oxygen level attainable by this P deoxidation treatment is said to be sufficient at 20 to 40 ppm, and the oxygen-free copper level (oxygen amount: 10 ppm or less ) Has not been deoxidized. Ordinary oxygen-free copper production facilities have a vacuum furnace or H ₂ to enable deoxidation to extremely low oxygen levels.
Although special equipment such as a gas reduction furnace for CO, CO, etc. is provided for advanced deoxidation, since P deoxidation copper production equipment is not equipped with such special equipment, P deoxidation is performed. To effectively utilize the copper manufacturing equipment for the production of P-containing oxygen-free copper,
A technique for reducing the oxygen content of P-deoxidized copper to the oxygen-free copper level must be established within the production line.

In P deoxidized copper, P used for deoxidation is 10
Although about 20 ppm is mixed, about 20 ppm or more of P may be required for P-containing low-oxygen copper. Therefore, it is necessary to consider a method of positively increasing the P content in some cases.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to utilize a conventional P-deoxidized copper production facility equipped with a shaft furnace to obtain oxygen. It is intended to establish a technique capable of producing P-containing low oxygen copper having an amount of 10 ppm or less and a P content of 10 to 140 ppm with high productivity.

[0009]

The method for producing P-containing low-oxygen copper according to the present invention, which has been able to solve the above-mentioned problems, is to use electrolytic copper ingot or pure copper-based scrap as a raw material, and use them in a shaft furnace. The molten metal is melted in a reducing atmosphere, and the molten metal is continuously supplied to the mold through the molten metal transfer gutter. The P content is adjusted in the molten metal transfer gutter, and an inert gas is blown into the molten metal to stir the molten metal. However, it has the gist of deoxidizing. At this time, the molten metal obtained in the shaft furnace is oxidized (refined) in a holding furnace to remove hydrogen and other oxidizing impurities, and then sent to a transfer trough to adjust the P content and deoxidize. If done, a higher quality P-containing low oxygen copper can be obtained. Moreover, in the above, by adjusting the P content in the finally obtained P-containing oxygen copper, the effect of addition (particularly high strength) can be effectively exhibited with almost no trouble due to P content. it can.

[0010]

In the present invention, electrolytic copper ingot originally having a small amount of impurities or pure copper waste is used as a raw material, and this is melted in a reducing atmosphere in a shaft furnace, and then this molten metal is usually sent to a holding furnace. When continuously feeding from the holding furnace to the mold through the transfer trough, the P content is adjusted on the transfer trough and deoxidation of oxygen-free copper to the oxygen level is continuously performed. By doing so, it is possible to obtain P-containing low oxygen copper, which enables efficient production of P-containing low oxygen copper by making good use of the P deoxidized copper production equipment using a shaft furnace. It was done. Therefore, the present invention is most characterized in that deoxidation is carried out to the oxygen level of oxygen-free copper on the transfer trough, and therefore the description will be made mainly on this deoxidation step.

As described above, in the conventional process for producing P-deoxidized copper using the shaft furnace, oxygen in the molten metal is removed as P ₂ O ₅ by adding P as a deoxidizing agent. At this time, since a part of P is mixed in the molten metal, P not only acts as a deoxidizing agent, but is also effectively utilized as a P source for improving strength. However, the oxygen content that can be achieved by this P deoxidation method is at most 20 to 40 ppm, and the oxygen content of 10 ppm or less required for oxygen-free copper cannot be achieved.

Therefore, research was conducted to establish a method capable of reducing the amount of oxygen to a level of 10 ppm or less in a transfer process using a transfer gutter. Then, first, a solid reducing agent (charcoal powder or the like) generally used as a method for reducing a molten metal made of iron and steel was used, and an attempt was made to add it to a copper molten metal flowing through a transfer trough to deoxidize it. That is, when a solid reducing agent is added to the molten steel and the molten metal is stirred, oxygen in the molten metal becomes CO ₂ by the following reaction, and then further reacts with C to become CO, and O ₂ + C → CO ₂ CO ₂ + C → 2CO ↑ The generated CO is sequentially burned on the surface of the molten steel by the heat of the molten steel and is diffused to the upper space. That is, the oxygen in the molten metal changes from CO ₂ to CO due to the reaction with the solid reducing agent and is sequentially diffused, so that the oxygen amount rapidly decreases within a relatively short time.

However, the deoxidation situation of the molten copper is quite different from the deoxidation situation of the above-mentioned molten steel. That is, according to the result of examining the gas component in the molten copper by the partial pressure equilibrium method, the reaction of C + O ₂ → CO ₂ proceeds rapidly,
The reaction of CO ₂ + C → 2CO was very slow, and it became clear that a large amount of CO ₂ was dissolved in the molten copper. This is thought to be due to the high solubility of CO _{2 in} the molten copper, and therefore deoxidation of the molten copper using the solid reducing agent is from a high oxygen level of several thousands to several tens of thousands ppm to an oxygen amount of several hundreds of ppm. Although effective for deoxidation treatment, it cannot be used for further deoxidation, and therefore cannot be applied to the present invention in which the target oxygen level to be reached is 10 ppm or less.

Therefore, as a result of further research aimed at efficiently removing CO ₂ dissolved in the copper melt and reducing the oxygen content to a level of 10 ppm or less, an inert gas was blown into the copper melt. CO in the molten metal in the inert gas bubbles
By adopting a method of diffusing and transferring ₂ and then floating it onto the surface of the molten metal together with the gas bubbles, it is possible to reduce the amount of oxygen to 10 ppm or less within a relatively short time when the molten copper is transferred through the transfer gutter. Do you get it.

This inert gas is blown by using a rotary nozzle, and the rotation thereof agitates the molten metal to spread the inert gas over the entire copper molten metal in the trough, and the rotation blows it at the tip of the nozzle. It has been found that if the gas bubbles are sheared to make the bubbles finer, the surface area of the inert gas bubbles is increased to enhance the CO ₂ trapping effect and the deoxidation can be proceeded more efficiently. The deoxidizing effect of the rotation of the inert gas blowing nozzle is such that the peripheral velocity of the tip opening of the blowing nozzle is 120 m / min, more preferably 300 m / min, and further preferably 400 m / min or more. It was confirmed that it can be surely exhibited by rotating like this. Moreover, under such condition setting, other gas components contained in the molten copper, such as hydrogen, are diffused and trapped by the fine inert gas bubbles and are efficiently removed, which is preferable.

Therefore, the inert gas blowing nozzle used in the present invention has a structure in which the blowing gas bubbles are made fine by its rotation, and the molten metal can be agitated to diffuse the fine bubbles throughout the molten metal. Those having a tip structure as shown in FIGS. 2A and 2B are used, for example. That is, FIG. 2A is a view of the tip of the nozzle seen from below,
FIG. 2B is a vertical cross-sectional view of the tip portion. The nozzle tip is formed in a cross shape and the slit S is provided on the lower surface side thereof.
The rotation causes a stirring force, and the blown gas is divided by the shearing force due to the rotation to be finely divided.

By the way, when P is deoxidized in the preceding step in carrying out the reduction by blowing the above-mentioned inert gas, the amount of oxygen in the molten copper in the P deoxidation step is several hundreds to several tens ppm. Since the amount of oxygen is reduced to 1, the amount of oxygen can be reduced to a level of 10 ppm or less simply by blowing an inert gas. However, when the P deoxidation treatment is not performed, or when the oxidation treatment for refining is performed in the holding furnace as described later, the oxygen content in the molten copper is 10% or less.
When the amount is more than 00 ppm, it is preferable to add a solid reducing agent powder such as charcoal together and perform the deoxidation reaction with C in parallel. In addition, when performing deoxidation using a solid reducing agent together, in addition to the method of adding the solid reducing agent powder to the surface of the molten metal, the solid reducing agent is lined on the inner surface of the transfer trough or the plate-like solid reducing agent is fixed and copper It is also possible to employ a method of contacting with the molten metal.

The P content can be adjusted at any time before or after the above-mentioned deoxidation by blowing an inert gas, and the simplest is to adjust the amount of P according to the target P content to Cu-
This is a method of adding P. When P deoxidation is performed before the inert gas blowing deoxidation, depending on the raw material, depending on the amount of P used for deoxidation, P of about 10 ppm or less is mixed in the molten copper. Therefore, when the target P content of the obtained P-containing low oxygen copper is less than this value, the P content should be kept small so that the P content after P deoxidation treatment does not exceed the target P content. . At this time, it is of course possible to use Cu-P as a P source for P deoxidation. Further, when it is desired to further reduce the P content, it is difficult to perform P removal on the transfer trough, so it is desirable to suppress the P content by increasing the blending ratio of electrolytic copper metal in the melting raw material stage.

In any case, the present invention has one purpose in order to improve the strength by positively containing P, and in order to effectively exert such a P containing effect, P is contained as a cast product. The amount should be 10 ppm or more, but if it is too large, it will cause embrittlement.
It is better to keep it below pm.

By the way, in the present invention, since high-purity electrolytic copper metal or pure copper-based scrap is originally used as the raw material for melting the shaft furnace, a refining treatment or the like is not particularly necessary prior to the above deoxidation in the transfer trough, though. Depending on the raw material circumstances, the shaft furnace melting conditions, etc., some impurities may be mixed or hydrogen may be contained. In such a case, the molten copper melted in the shaft furnace is temporarily stored in a holding furnace, and in this portion, it is refined using a solid oxidizer (Cu ₂ O, CuO, etc.) or a gaseous oxidizer (air, oxygen, etc.), It is desired to reduce oxidizing impurities and hydrogen.

For example, the oxygen content of oxygen-free copper is 1 ppm.
It is desired to suppress the content to less than about 10%, and it is preferable to reduce the hydrogen content to less than about 1 ppm even in the P-containing low oxygen copper according to the present invention. According to the present invention, as described above, in the deoxidizing step by blowing the inert gas in the transfer trough, hydrogen in the copper melt is also diffused and collected in the finely divided inert gas bubbles and simultaneously removed. . However, if a large amount of hydrogen is contained in the molten copper, most of the hydrogen will be removed at this point if the above refining (oxidation) treatment is performed in the holding furnace prior to the treatment in the transfer gutter. Therefore, the time required for hydrogen removal in the transfer trough is shortened, and a P-containing low oxygen copper having an extremely low hydrogen content can be obtained. In this case, since a large amount of oxygen is taken into the molten copper in the refining step, it is desirable to use the inert gas blowing and the addition of the solid reducing agent together in the deoxidizing step in the transfer trough.

[0022]

EFFECTS OF THE INVENTION The present invention is configured as described above, and effectively utilizes a shaft furnace melting facility or uses P deoxidized copper as a raw material, and a gas component by blowing an inert gas in a transfer trough. In order to efficiently produce P-containing low oxygen copper having excellent thermal / electrical properties and strength properties, it is possible to efficiently produce P-containing low-oxygen copper by diffusion-capturing or using a solid deoxidizing agent together with it and adjusting the P content. became.

[0023]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and may be appropriately applied within a range compatible with the gist of the preceding and the following. Modifications can of course be made, and all of them are included in the technical scope of the present invention.

Using the apparatus schematically shown in FIG. 1, P-containing low oxygen copper was melted and cast under the conditions shown in Examples 1 and 2 below. In FIG. 1, 1 is a shaft furnace, 2 is a holding furnace, 3 is a transfer gutter, and 4 is a continuous casting apparatus.

Electric copper ingot and pure copper waste (melting raw material) are charged from the upper part of the shaft furnace 1 and the molten copper discharged from the shaft furnace 1 is once stored in the holding furnace 2 and subsequently transferred. Three
And sent to the continuous casting device 4. A rotary inert gas blowing nozzle 5 as shown in FIG. 2 is immersed in the transfer trough 3, and the inert gas (Ar) is blown as fine bubbles while the nozzle 5 is rotated. By stirring the molten metal, the bubbles are diffused throughout the molten metal, and the solid reducing agent (charcoal) powder 6 is sprayed on the molten metal surface. Then, the molten copper is sampled at a suitable position of the transfer gutter 3 to measure the P content, and P is added as Cu-P to the target P content of the obtained P-containing low oxygen copper. , P content was adjusted.

Example 1 P-containing low oxygen copper was melted and cast under the following conditions. (Melting raw material): electrolytic copper metal (50%) + P deoxidized copper scrap (5
0%) (Treatment conditions): Shaft furnace melting: 15 tons / hour, 1250 ° C. Holding furnace: 20 tons capacity, 1250 ° C., LNG-fired transfer bath trough: Transfer without heating source, 15 tons / hour Solid reducing agent ( Charcoal powder, 20 kg / ton, addition of molten metal) Inert gas injection: Nozzle radius 10 cmφ, rotation speed 60
0 rpm (peripheral speed: 370 m / min), 40 N liters /
Ar blown in minutes P amount adjustment: Add insufficient amount as Cu-P in molten metal analysis (casting): Semi-continuous casting, 300 mmφ billet, 4 pieces The quality of the obtained cast product is as follows, and P content is included. The quality of the low oxygen copper was sufficiently satisfied. (Quality) P: 30 ppm, O ₂ : 0.1 ppm or less, H ₂ : 0.
3 ppm or less N ₂ : 0.1 ppm or less, CO ₂ : 0.1 ppm or less, C
O: 0.1 ppm or less

Example 2 P-containing low oxygen copper was melted and cast under the following conditions. (Melting raw material): electrolytic copper metal (90%) + P deoxidized copper scrap (1
0%) (Treatment conditions): Shaft furnace melting: 15 tons / hour, 1250 ° C Holding furnace: 20 tons capacity, 1250 ° C, LNG-fired Refining (oxidation) treatment: By blowing air or adding CuO
The amount of O ₂ in the molten metal was increased from 50 ppm to 1000 ppm, whereby the amount of H ₂ in the molten metal was increased from 2.0 ppm to 0.
It was reduced to 3 ppm. Transfer gutter: Transfer without heating source, 15 tons / hour Solid reducing agent (charcoal powder, 20 kg / ton, addition of molten metal surface) Inert gas blowing: Nozzle radius 10 cmφ, rotation speed 60
0 rpm (peripheral speed: 370 m / min), 40 N liters /
Ar blowing P amount adjustment by minute: Addition of deficient amount as Cu-P in molten metal analysis The quality of the cast product obtained is as follows, and sufficiently satisfied the quality as P-containing low oxygen copper. . (Quality) P: 10 ppm, O ₂ : 0.1 ppm or less, H ₂ : 0.
3 ppm or less N ₂ : 0.1 ppm or less, CO ₂ : 0.1 ppm or less, C
O: 0.1 ppm or less

[Brief description of drawings]

FIG. 1 is an explanatory view showing an apparatus for producing P-containing low oxygen copper used in Examples.

FIG. 2 is an explanatory view showing a preferred example of an inert gas blowing nozzle used in the present invention.

[Explanation of symbols]

 1 Shaft Furnace 2 Holding Furnace 3 Transfer Tank 4 Casting Device 5 Inert Gas Injection Nozzle 6 Solid Reducing Agent

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiro Yokochi 65 Hirasawa, Hadano City, Kanagawa Prefecture Kobe Steel Works, Ltd. Hadano Plant (72) Inventor Takanori Wada 65 Hirasawa, Hadano City, Kanagawa Kobe Steel Works Hadano Plant (72) Inventor Keiichi Kumagai 65 Hirasawa, Hadano City, Kanagawa Prefecture Kobe Steel Works Hadano Plant

Claims (4)

[Claims] 1. An electrolytic copper ingot or pure copper-based scraps as raw materials are melted in a shaft furnace, and the molten metal is continuously supplied to a mold through a transfer gutter. A method for producing P-containing low oxygen copper using a shaft furnace, which comprises adjusting the content and blowing an inert gas into the molten metal to deoxidize the molten metal while stirring. 2. The method for producing P-containing low oxygen copper according to claim 1, wherein the raw material melted in the shaft furnace is subjected to an oxidation treatment in a holding furnace and then sent to a transfer gutter. 3. The method according to claim 1, wherein the P content is adjusted by adding Cu—P. 4. The method according to claim 1, wherein the P content in the cast P-containing low oxygen copper is 10 to 140 ppm.