JP2000328152A - Method for degassing molten copper or copper alloy and continuous melting and casting equipment of copper or copper alloy incorporated with apparatus for executing this degassing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a degassing method of molten copper, in which gaseous oxygen and gaseous hydrogen in the molten copper can be stably and well removed for a long time, and a continuous melting and casting equipment of the copper or copper alloy incorporated with an apparatus for executing this degassing method. SOLUTION: This degassing method is executed by dipping a carbon member 1 containing >=90 wt.% fixed carbon and <1 wt.% (containing 0%) ash content into the molten copper or copper alloy 3, generating carbon dioxide gas bubbles between the carbon member 1 and the gaseous oxygen in the molten metal 3 and absorbing the gaseous hydrogen in the carbon dioxide gas bubbles to remove the gaseous oxygen and the gaseous hydrogen in the molten metal 3. Further, the continuous melting and casting equipment of the copper or copper alloy is an equipment by incorporating the apparatus for executing the degassing method to at least one among a melting furnace, rounder A, holding furnace, rounder B and casting machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degassing method capable of removing oxygen gas and hydrogen gas in a molten copper or copper alloy (hereinafter referred to as molten copper) stably and satisfactorily for a long time.

[0002]

2. Description of the Related Art Oxygen and hydrogen contained in molten copper cause core cracks in ingots and form pinholes and blowholes in ingots to impair product quality and characteristics. For this reason, the following various methods are applied to the degassing method of molten copper. A method of floating charcoal or pine logs on the surface of molten copper. A method in which charcoal is immersed in molten copper (JP-A-63-108946).
A method of bubbling ammonia gas, ammonia decomposition gas, and hydrogen-containing gas into molten copper. A method of adding a small amount of an element (P, Mg, Zr, Si, Ca, Al, etc.) having a high affinity for oxygen to molten copper. A method of bubbling an inert gas into molten copper. A method in which molten copper is kept under reduced pressure or in a vacuum atmosphere (Japanese Patent Application No. 60-61667).

[0003]

However, each of the above-mentioned conventional methods has the following problems. That is,
In the method (1), only the oxygen gas is removed, and the hydrogen gas is not removed or increases. Further, the charcoal surface is ashed with the degassing, and the degassing effect is reduced with time. Further, the method is applicable only to a small amount of molten copper of about 0.5 ton / hr or low oxygen molten copper. In the method (1), an excessive addition causes a decrease in conductivity. In other methods, it is difficult to remove oxygen gas. Further maintenance of the atmosphere requires a great deal of maintenance costs. As described above, in the conventional method, it has been difficult to stably and satisfactorily remove oxygen gas and hydrogen gas for a long time. The present invention provides a method for degassing molten copper capable of removing oxygen gas and hydrogen gas in molten copper stably and satisfactorily for a long time, and a continuous melting casting of copper or copper alloy incorporating an apparatus for performing the degassing method. The purpose is to provide equipment.

[0004]

According to the first aspect of the present invention,
A carbon member containing 90% by weight or more of fixed carbon and less than 1% by weight (including 0% by weight) of ash is immersed in a molten copper or copper alloy, and a carbon dioxide gas bubble is formed between the carbon member and oxygen gas in the molten metal. And removing the oxygen gas and the hydrogen gas in the molten copper by absorbing hydrogen gas in the carbon dioxide gas bubbles.

According to a second aspect of the present invention, a porous carbon member having a large number of fine holes is used as the carbon member, and an inert gas is blown into the molten copper from the fine holes of the carbon member. Item 4. A method for degassing a molten copper or copper alloy according to Item 1.

According to a third aspect of the present invention, there is provided the method for degassing a molten copper or copper alloy according to the first aspect, wherein an inert gas bubble is caused to float along the surface of the carbon member.

The invention according to claim 4 is characterized in that at least one of the molten metal and the carbon member is degassed while applying vibration to the molten metal or the carbon member. This is a method for degassing molten alloy.

According to a fifth aspect of the present invention, there is provided a copper or copper alloy continuous melting and casting apparatus mainly including a melting furnace, a rounder A, a holding furnace, a rounder B, and a casting machine. A continuous melting and casting apparatus for copper or a copper alloy, wherein any one of the apparatuses for performing the degassing method according to claim 1, 2, 3, or 4 is incorporated.

[0009]

According to the first aspect of the present invention, the oxygen gas in the molten copper reacts with the carbon of the carbon member on the surface of the carbon member to generate carbon dioxide gas bubbles. When the carbon dioxide gas bubbles grow on the surface of the carbon member and exceed the critical size, they are separated from the surface of the carbon member, float in the molten copper, and are released into the atmosphere. The hydrogen gas in the molten copper is absorbed by the carbon dioxide gas bubbles and is released together with the oxygen gas. New molten copper is always supplied to the carbon member surface by the heat flow, so that a good degassing effect is maintained for a long time. In the present invention, the fixed carbon of the carbon member is specified to be 90% by weight or more and the ash content is specified to be less than 1% by weight. Therefore, the carbon member surface is not covered with the ash, and the fixed carbon is sufficiently supplied. Gas bubbles are successfully generated for a long time. Here, the fixed carbon is a residue obtained by removing water, volatile matter, and ash from the carbon member.

According to a second aspect of the present invention, there is provided the degassing method according to the first aspect, wherein a porous carbon member having a large number of fine holes is used in the carbon member, and the inert gas is melted through the fine holes of the carbon member. This is a degassing method that blows into the interior. The carbon dioxide gas bubbles generated on the surface of the carbon member are adsorbed by the inert gas blown from the micropores and leave the surface of the carbon member in a small size, so that the removal of oxygen gas in the molten copper is promoted. Further, the hydrogen gas in the molten copper is absorbed not only by the carbon dioxide gas bubbles but also by the inert gas bubbles, so that the hydrogen gas is also removed more efficiently.

According to a third aspect of the present invention, there is provided the degassing method according to the first aspect, wherein the inert gas bubbles float on the surface of the carbon member immersed in the molten copper. The generated carbon dioxide gas bubbles are adsorbed by the floating inert gas bubbles and separate from the surface of the carbon member in a small size, so that the removal of oxygen gas in the molten copper is promoted. Further, the hydrogen gas in the molten copper is absorbed not only by the carbon dioxide gas bubbles but also by the inert gas bubbles, so that the hydrogen gas is also removed more efficiently.

According to a fourth aspect of the present invention, vibration is applied to at least one of the molten copper and the carbon member to generate carbon dioxide gas bubbles on the surface of the carbon member and to separate the carbon dioxide gas bubbles from the surface of the carbon member. And a degassing method in which the supply of molten copper to the surface of the carbon member is promoted. Vibrating both the molten copper and the carbon member provides a greater effect. Any vibration method such as mechanical vibration and ultrasonic vibration is applied to the vibration method. The degassing effect is further improved by using both vibration and inert gas blowing.

In the present invention, the degassing effect can be further improved by a method such as roughening the surface of the carbon member or forming the carbon member into a shape having a large surface area.
INDUSTRIAL APPLICABILITY The present invention can be applied to degassing of molten copper of any copper and copper alloys, including oxygen-free copper, low-oxygen copper, and diluted copper alloy, to obtain excellent effects.

The method of the present invention will be specifically described below with reference to the drawings. FIG. 1A is an explanatory side view showing a first embodiment of the method of the present invention. A plurality of plate-like carbon members 1 are attached to a rounder B connecting a molten copper holding furnace and a casting machine.
The degassing device 2 is formed by vertically disposing the surface of the degassing device so as to be parallel to the flow direction of the molten copper, and degassing is performed by flowing the molten copper 3 between the carbon members 1 of the degassing device 2. In this degassing method, as described above, while the molten copper 3 moves inside the degassing device 2, oxygen in the molten copper 3 reacts with the carbon member 1 to generate carbon dioxide gas bubbles, When the bubble grows to the critical size, the bubble separates from the surface of the carbon member 1, floats in the molten copper 3, and is released to the atmosphere. Hydrogen in the molten copper 3 is absorbed in the carbon dioxide gas bubbles and removed together with the carbon dioxide gas. The arrow in the figure is the direction in which the molten copper flows.

FIG. 1B is an explanatory view of a degassing method according to a second embodiment of the present invention. This method is the same as the method shown in FIG. 1A except that a plate-like carbon member 5 having a large number of through holes 4 is used as the carbon member. This method
Since the contact area of the carbon member 5 with the molten copper 3 is large, FIG.
The degassing effect is superior to the method shown in (a).

FIG. 1C is an explanatory view of a degassing method according to a third embodiment of the present invention. This method is the same as the degassing method shown in FIG. 1A except that the granular carbon member 6 is used as the carbon member. The granular carbon member 6 is prevented from flowing out by a retaining frame 7 provided above the rounder B. In this method, since the carbon member 6 is granular, the surface area is larger than that of the plate-like carbon member 1 and, therefore, is superior in the degassing effect as compared with the method shown in FIG.

FIG. 1D is an explanatory view of a degassing method according to a fourth embodiment of the present invention. This method is the same as the degassing method shown in FIG. 1C except that the stopper frame 7 is also provided below the rounder B. According to this method, a larger number of granular carbon members 6 can be arranged as compared with the method shown in FIG. 1 (c), so that the degassing effect is superior to the method shown in FIG. 1 (d).

FIG. 1E is an explanatory view of a degassing method according to a fifth embodiment of the present invention. This method uses Rounder B
A plurality of porous block-shaped carbon members 8 having a large number of micropores are arranged at predetermined intervals in the longitudinal direction of the rounder B, and the molten copper 3 flowing between the carbon members and above the carbon members is provided with In this method, an inert gas (indicated by a small circle in the figure) is blown out of the fine holes of the carbon member 8 to degas.
In this method, detachment of carbon dioxide gas bubbles from the carbon member 8 is promoted by the inert gas, and hydrogen gas in the molten copper is absorbed by the inert gas bubbles as well as the carbon dioxide gas bubbles. The gas effect is further improved.

FIG. 1F is an explanatory view of a degassing method according to a sixth embodiment of the present invention. This method uses Rounder B
Except that the porous block-shaped carbon member 8 is arranged above the above, the degassing method shown in FIG. According to this method, the installation and replacement of the block-shaped carbon member 8 can be performed more easily than the method shown in FIG.

FIGS. 2A, 2B and 2C are explanatory views of a degassing method showing seventh, eighth and ninth embodiments of the present invention, respectively. This method is similar to that shown in FIG. 1 except that a gas injecting device 9 made of a porous plug is attached to the floor of the rounder B, and an inert gas (not shown) is blown out from the blowing device 9 into molten copper. This is the same as the degassing method shown in 1 (a), (b) and (c). In the method shown in FIGS. 2A, 2B, and 2C, the separation of the carbon dioxide gas bubbles from the carbon member is promoted by the inert gas, and the hydrogen gas in the molten copper is not limited to the carbon dioxide gas bubbles. As it is absorbed by inert gas bubbles,
The degassing effect is further improved as compared with the methods shown in FIGS.

FIG. 2D is an explanatory view of a degassing method according to a tenth embodiment of the present invention. In this method, a plurality of carbon members 10 having a right-angled triangular cross section are mounted on the upper part of the rounder B such that the inclined surface 11 is directed upward and downward, and a plurality of gas blowing holes 12 are formed on the inclined surface 11 of the carbon member 10. And degassing while blowing an inert gas into the molten copper 3. The oxygen in the molten copper 3 forms a carbon dioxide gas on the inclined surface 11 of the carbon member 10, and the carbon dioxide gas bubbles are small while the inert gas rises along the inclined surface 11 (shown by a small circle in the figure). Adsorbed on the carbon member 10
It is released from the surface, floats in the molten copper 3 and is released into the atmosphere. During this time, the hydrogen gas in the molten copper 3 is absorbed not only by the carbon dioxide gas bubbles but also by the inert gas. Therefore, the degassing effect is extremely large.

Next, the continuous melting and casting equipment of the present invention will be specifically described with reference to the drawings. FIG. 3A is an explanatory side view showing the first embodiment of the continuous melting and casting equipment of the present invention. This continuous melting and casting equipment has a shaft furnace (melting furnace) 2
1, a rounder A, a holding furnace 22, a rounder B, and a continuous casting machine 23 as main parts;
2, and a degassing device 2 for performing the degassing method of the present invention in the rounder B.

FIG. 3 (b) is an explanatory side view showing a second embodiment of the continuous melting and casting apparatus of the present invention. This continuous melting and casting equipment includes a reflection furnace (melting furnace) 25, a rounder A, a holding furnace 22, a rounder B, and a continuous casting machine 23 as main parts, and includes a reflection furnace 25, a rounder A, a holding furnace 22, and a rounder B. And a degassing device 2 for performing the degassing method of the present invention.

FIG. 3C is an explanatory side view showing a third embodiment of the continuous melting and casting apparatus of the present invention. This continuous melting and casting equipment has an electric furnace (melting furnace) 26, a rounder A, a holding furnace 22, a rounder B, and a continuous casting machine 23 as main parts, and the rounder A, the holding furnace 22, and the rounder B include:
The degassing apparatus 2 for performing the degassing method of the present invention is incorporated therein.

[0025]

The present invention will be described below in detail with reference to examples. (Example 1) A copper ingot (ingot) was continuously cast by a semi-continuous casting method using the continuous melting casting equipment shown in FIG. The electrolytic copper is melted in the shaft furnace 21 to obtain molten copper 3,
This is transferred to the holding furnace 22 through the rounder A, the foreign matter is settled or floated and separated in the holding furnace 22, and the temperature of the molten copper 3 is adjusted to 1120 ° C., and then the molten copper 3 in the holding furnace 22 is passed through the rounder B. And supplied to a vertical continuous casting machine 23 to continuously cast an ingot 25 of pure copper. Degassing was performed only in Rounder B. Degassing was carried out by any of the methods shown in FIGS. 1 (a), (c) and (e) and FIGS. 2 (a), (c) and (d). The composition of the carbon member was the composition specified in the present invention.
The degassing device was located over the entire width of the rounder B. The length of the degasser is 4 m. ,

(Comparative Example 1) Degassing was also performed by a conventional method using charcoal granules, coke, and the like.

In Example 1 and Comparative Example 1 (conventional method),
The oxygen content and the hydrogen content in the molten copper were measured before and after the degassing treatment, and the degassing effect of each was examined. The amount of oxygen and the amount of hydrogen were analyzed by an analyzer manufactured by LECO, using a sample quenched and collected using a glass sampler for vacuum suction. Tables 1 and 2 show the results together with the degassing conditions.

[0028]

[Table 1]

[0029]

[Table 2]

As is clear from Tables 1 and 2,
In Nos. 1 to 21, the amounts of oxygen and hydrogen were significantly reduced by degassing. On the other hand, in Comparative Example 1 (conventional method), the fixed carbon of the carbon member used was small (No. 26,
27) The degassing effect was not sufficiently obtained in either case due to the large amount of ash (No. 25) or the small amount of fixed carbon and the large amount of ash (No. 22 to 24).

FIG. 4 shows No. 19 of the present invention example and No. 23 of the conventional method shown in Table 2 with respect to the change with time in the amount of oxygen in the molten copper. In No. 19 of the present invention, the oxygen amount is stable at a low level immediately after the start of degassing, whereas in the conventional method No. 23, the oxygen amount is low only at the very beginning of the degassing start, After that, the degassing effect is not recognized after 60 minutes.

Nos. 1 to 21 of the present invention and No. 22 of the conventional method
To 27 for the initial (after 10 minutes) oxygen removal amount F
= (Hydrogen amount before degassing-hydrogen amount after degassing) x molten copper amount, and oxygen removal amount G after 60 minutes = ((hydrogen amount before degassing-hydrogen amount after degassing) x molten copper amount) FIG. 5A shows the relationship between the two (F is plotted on the horizontal axis and G on the vertical axis). In the example of the present invention, the same amount of oxygen removal as in the initial stage was observed even after the lapse of 60 minutes, but in the comparative example, the amount of oxygen removed was significantly reduced after the lapse of 60 minutes. Regarding the amount of hydrogen, the removal amount at the initial stage (after 10 minutes) and after 60 minutes was determined. As shown in FIG. 5 (b), in the example of the present invention, a large amount of hydrogen was removed after the elapse of 60 minutes, which was almost the same as the initial amount. However, in the conventional method, the amount of hydrogen was increased after the elapse of 60 minutes. .

(Example 2) Except that the ultrasonic vibration was applied to the carbon member or the molten copper, casting was performed in the same manner as in the first embodiment, and the amounts of oxygen and hydrogen in the molten copper were determined in the same manner as in the first embodiment. Was measured before and after the degassing treatment. The degassing apparatus shown in FIGS. 1A and 2C was used. Table 3 shows the results.

[0034]

[Table 3]

As is evident from Table 3, a significant decrease in the amount of oxygen was observed by the application of vibration. The amount of hydrogen has also been reduced,
It did not decrease as much as the amount of oxygen. The amount of hydrogen has been omitted from the display.

Example 3 A pure copper ingot was semi-continuously cast using the continuous ingot equipment shown in FIGS. 3 (a) to 3 (c). Degassing was performed in at least two of the rounder A, the holding furnace 22, and the rounder B. The carbon member used was fixed carbon 99 wt% and ash content 0.5 wt%.

Comparative Example 2 Pure copper ingots were produced in the same manner as in Example 3 except that degassing was carried out by a conventional method in which charcoal (82% by weight or more of fixed carbon, ash content: 2.2% by weight) was immersed in a holding furnace. Was continuously cast.

The degassing effect in Example 3 and Comparative Example 2 (conventional method) was examined by the same method as in Example 1. However, the analysis sample was collected at the melting furnace outlet and in the mold 60 minutes after the start of casting. Table 4 shows the results.

[0039]

[Table 4]

As is clear from Table 4, No. 1
For 41 to 44, both the oxygen content and the hydrogen content were greatly reduced. In contrast, in the conventional method, the amount of oxygen decreased by 20 to 30%, but the amount of hydrogen increased. Each of the ingots produced by the method of the present invention was of high quality without any core cracks, pinholes, blowholes and the like.

[0041]

As described above, in the present invention, fixed carbon is 90 wt% or more, and ash is less than 1 wt% (including 0 wt%).
The carbon member contained is immersed in a copper or copper alloy melt to generate carbon dioxide gas bubbles between the carbon member and the oxygen gas in the molten copper, and the hydrogen gas is absorbed in the carbon gas bubbles. Gas and hydrogen gas are stably removed well for a long time. Further, by blowing an inert gas or vibrating at least one of the carbon member and the molten copper, desorption of carbon dioxide gas bubbles from the surface of the carbon member and absorption of hydrogen gas into the bubbles are promoted, and a degassing effect is obtained. Is improved. According to the continuous melting and casting equipment of the present invention in which the apparatus for performing the degassing method is incorporated in at least one of a melting furnace, a rounder A, a holding furnace, a rounder B, and a continuous casting machine, a high-quality ingot can be lengthened. Time stable production Therefore, an industrially remarkable effect is achieved.

[Brief description of the drawings]

FIGS. 1A to 1F are side explanatory views showing first to sixth embodiments of the degassing method of the present invention, respectively.

FIGS. 2A to 2D are side explanatory views showing seventh to tenth embodiments of the degassing method of the present invention, respectively.

FIGS. 3A to 3C are explanatory views showing first to third embodiments of the continuous melting and casting apparatus of the present invention, respectively.

FIG. 4 is a diagram showing a change over time in the amount of oxygen in molten copper.

FIG. 5A is a diagram showing the relationship between the initial amount and the oxygen removal amount after 60 minutes, and FIG. 5B is a diagram showing the relationship between the initial period and the hydrogen removal amount after 60 minutes.

[Explanation of symbols]

Reference Signs List 1 plate-shaped carbon member 2 degassing device 3 molten copper 4 through-hole provided in plate-shaped carbon member 5 plate-shaped carbon member provided with through-hole 6 granular carbon member 7 stopper frame of granular carbon member 8 porous block-shaped carbon 9 Gas injection device made of porous plug 10 Carbon member having a right-angled triangle in vertical section 11 Inclined surface of carbon member having a right-angled triangle 12 Gas injection hole 21 opening on an inclined surface of carbon member having a right-angled triangle in cross section 21 Shaft Furnace (melting furnace) 22 Holding furnace 23 Continuous casting machine 25 Reflection furnace (melting furnace) 26 Electric furnace (melting furnace) A rounder B rounder

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoshi Teshigahara 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 4K001 AA09 BA23 EA04 GA13 GA19 GB12

Claims (5)

[Claims] 1. A fixed carbon content of 90% by weight or more and an ash content of 1% by weight.
The carbon member containing less than 0 wt% (including 0 wt%) is immersed in the molten copper or copper alloy to generate carbon dioxide gas bubbles between the carbon member and the oxygen gas in the molten metal, and the hydrogen is contained in the carbon dioxide gas bubbles. A method for degassing a molten copper or copper alloy, comprising absorbing gas to remove oxygen gas and hydrogen gas in the molten copper. 2. The method according to claim 1, wherein a porous carbon member having a large number of fine holes is used as the carbon member, and an inert gas is blown into the molten copper from the fine holes of the carbon member.
A method for degassing the copper or copper alloy melt described. 3. The method for degassing a molten copper or copper alloy according to claim 1, wherein an inert gas bubble is levitated along the surface of the carbon member. 4. The method for degassing a molten copper or copper alloy according to claim 1, wherein the degassing is performed while applying vibration to at least one of the molten metal and the carbon member. . 5. A copper or copper alloy continuous melting and casting facility comprising a melting furnace, a rounder A, a holding furnace, a rounder B, and a casting machine as main parts, wherein at least one of the main parts is provided. 3. A continuous melting and casting facility for copper or copper alloy, wherein any one of the devices for performing the degassing method according to 3 or 4 is incorporated.