JP2002030358A - Method and apparatus for producing low oxygen copper cast block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method and a production apparatus with which dehydrogenizing treatment is applied without securing a long transporting distance and a high quality low oxygen copper cast block restraining the formation of blow hole can be produced in a large quantity at a low cost. SOLUTION: The production apparatus 1 for continuously producing the low oxygen copper cast block 23 from molten copper, is constituted so as to provide a melting furnace A for producing the molten copper by performing the combustion in a reducing atmosphere, a holding furnace B for holding the molten copper fed from the melting furnace A to a prescribed temperature, a casting trough C for transporting the molten copper fed from the holding furnace B to a tundish 5 while sealing with non-oxidizing atmosphere, a degassing means 33 for applying the dehydrogenizing treatment to the molten copper while passing through the casting trough C, a continuous caster D for continuously producing a cast copper material 21 from the molten copper supplied from the tundish 5, a cut-off means E for cutting off the cast copper material 21 to a prescribed length and a carry-out means F.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously producing a low-oxygen copper ingot with a reduced oxygen content by continuously casting molten copper from a melting furnace using a continuous casting machine. The present invention relates to the manufacturing apparatus.

[0002]

2. Description of the Related Art Copper ingots, in particular, oxygen content of 20p
As a method for producing a low-oxygen copper ingot that is suppressed to below pm, a molten copper is generated using an electric induction furnace such as a channel furnace or a multi-furnace, and the molten copper is continuously maintained while being kept airtight during a transfer process. The method of transferring to a casting machine and manufacturing a casting lump was common. As described above, in the case of manufacturing using an electric induction furnace, there is an advantage that a high temperature can be easily obtained by a simple operation, and the quality is stable because a chemical reaction is not involved during the production of molten copper. . However, on the other hand, it has disadvantages such as high construction cost and operation cost and low productivity.

[0003]

In order to produce a large amount of copper ingot at low cost, a production method using a gas furnace such as a shaft furnace is preferable. However, when such a gas furnace is used,
In order to cause combustion in the furnace, that is, an oxidation reaction, a reduction treatment of the molten copper must be performed. This is a disadvantage that cannot be obtained when an electric induction furnace is used. Therefore, if the produced molten copper is subjected to a reducing treatment with a reducing gas and / or an inert gas in the transfer process to reduce the oxygen concentration and then is not transferred to a continuous casting machine, a low oxygen copper ingot is manufactured. I can't. However, simply performing the deoxidation treatment in this way may cause holes to occur in the low-oxygen copper ingot and cause defects such as blistering, and in such a case, the quality of the low-oxygen copper ingot deteriorates. Would. For this reason, it is generally considered very difficult to produce high-quality low-oxygen copper ingots using a gas furnace, and low-oxygen copper ingots are produced exclusively using an electric induction furnace. It is a fact.

[0004] Such holes are caused by water vapor (H ₂ O) bubbles generated by the combination, because the solubility of hydrogen and oxygen in the molten copper decreases during the solidification of the molten copper. These bubbles are trapped during the cooling and solidification of the molten copper, and remain in the low-oxygen copper ingot to generate holes. Thermodynamically, the concentrations of hydrogen and oxygen in the molten copper have a relationship represented by the following equation. [H] ² [O] = p _H2O · K Formula (A) where [H]: hydrogen concentration in molten copper [O]: oxygen concentration in molten copper p _H2O : water vapor content in atmosphere Pressure K: Equilibrium constant.

[0005] The equilibrium constant K is a function of temperature and becomes a constant at a constant temperature, so that the oxygen concentration and the hydrogen concentration in the molten copper have an inversely proportional relationship. Therefore, the more the deoxidation treatment is performed by reduction, the higher the hydrogen concentration becomes, and holes are easily formed at the time of solidification, and only a low-quality low-oxygen copper ingot can be manufactured. That is, unless not only the deoxidation treatment but also the dehydrogenation treatment is performed, a large amount of holes are formed during solidification, and a high-quality low-oxygen copper ingot cannot be produced.

[0006] On the other hand, it is possible to obtain molten copper having a low hydrogen concentration by melting in a state close to complete combustion by an oxidation-reduction method, which is a general degassing method. A long transfer distance must be secured, which is not practical.

[0007] The present invention has been made in view of the above-mentioned circumstances, and provides a high-quality low-oxygen copper ingot in which dehydrogenation can be performed without securing a long transfer distance and the formation of holes is suppressed at a low cost. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus that can be manufactured in large quantities.

[0008]

According to the first aspect of the present invention,
A method for continuously producing a low oxygen copper ingot from molten copper, comprising: a molten copper producing step of producing molten copper by burning a melting furnace in a reducing atmosphere; Copper,
A molten copper transfer step of transferring to a tundish using a casting gutter that can be sealed in a non-oxidizing atmosphere, and a degassing step of performing dehydrogenation treatment on molten copper provided in the casting gutter,
A continuous casting step of supplying the molten copper to a continuous casting machine to continuously produce a cast copper material, and a cutting step of cutting the cast copper material into a predetermined length to form a low oxygen copper ingot. It is characterized by the following.

In this method for producing a low-oxygen copper ingot, combustion is performed in a melting furnace in a reducing atmosphere to deoxidize the molten copper, and the molten copper is sealed in a non-oxidizing atmosphere in a casting gutter to form a tank. Transferred to the dish. This molten copper has a high hydrogen concentration because the oxygen concentration and the hydrogen concentration are in inverse proportion to each other, but is subjected to a dehydrogenation treatment in a subsequent degassing step. For this reason, the hydrogen concentration that increases as the deoxidation treatment is performed by reduction decreases, and the release of gas during solidification decreases, whereby the formation of holes in the cast copper material can be suppressed.

According to a second aspect of the present invention, there is provided the method for producing a low-oxygen copper ingot according to the first aspect, wherein the degassing step performs a dehydrogenation treatment by stirring the molten copper. It is characterized by.

In this method for producing a low-oxygen copper ingot, dehydrogenation can be performed by stirring the molten copper to forcibly remove hydrogen in the molten copper. That is, the molten copper before being transferred to the tundish is stirred, and the contact between the inert gas blown to form a non-oxidizing atmosphere and the molten copper is improved. At this time, since the hydrogen partial pressure in the inert gas is extremely smaller than the hydrogen partial pressure in the molten copper, the hydrogen in the molten copper is taken into the inert gas, and the dehydrogenation of the molten copper can be performed.

According to a third aspect of the present invention, there is provided the method for producing a low oxygen copper ingot according to the second aspect, wherein the stirring means comprises:
The stirring is performed by meandering the flow path of the passing molten copper.

In this method for producing a low-oxygen copper ingot, molten copper passing through a casting gutter is flowed in a meandering manner, and is agitated by violent flow. In other words, because the molten copper itself can be automatically stirred by its own flow, the molten copper flowing through the casting gutter has a chance to come into contact with the inert gas evenly,
The efficiency of the dehydrogenation treatment is further improved. In this case, for example, a rod-shaped or plate-shaped weir provided in a flow path of molten copper is suitable.
A plurality of weirs may be provided in the flow direction of the molten copper, or a plurality of weirs may be provided in a direction orthogonal to the flow of the molten copper. Furthermore, if this weir is made of, for example, carbon, deoxidation can be efficiently performed by contact between molten copper and carbon.

According to a fourth aspect of the present invention, there is provided a production apparatus for continuously producing a low oxygen copper ingot from molten copper, comprising: a melting furnace for producing molten copper by burning in a reducing atmosphere; A holding furnace for holding the molten copper sent from the melting furnace at a predetermined temperature, a casting gutter for sealing the molten copper sent from the holding furnace in a non-oxidizing atmosphere and transferring it to a tundish, A degassing means for dehydrogenating molten copper passing therethrough, a continuous casting machine for continuously producing a cast copper material from the molten copper supplied from the tundish, and cutting the cast copper material to a predetermined length. And cutting means. The invention according to claim 5 is the apparatus for producing a low-oxygen copper ingot according to claim 4, wherein the degassing means is a stirring means for stirring the molten copper. . Furthermore,
The invention according to claim 6 is the apparatus for producing a low-oxygen copper ingot according to claim 5, wherein the stirring means is configured by a weir that meanders the flow path of the passing molten copper. It is characterized by.

Since the apparatus for producing a low-oxygen copper ingot is constituted as described above, the method for producing a low-oxygen copper ingot according to the first to third aspects can be suitably carried out.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a low oxygen copper ingot manufacturing apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram schematically showing an apparatus for manufacturing a low-oxygen copper ingot according to the present invention, and FIG. 2 is an enlarged view of a main part of the casting gutter of FIG. FIG.

The low oxygen copper ingot manufacturing apparatus 1 includes a melting furnace A, a holding furnace B, a casting gutter C, a continuous casting machine D, a cutting means E, and an unloading means F. Have been.

As the melting furnace A, a gas furnace having a cylindrical furnace body, for example, a shaft furnace is suitably used.
At the lower part of the melting furnace A, a plurality of burners (not shown) are provided in a circumferential direction in multiple stages in a vertical direction. In the melting furnace A, combustion is performed in a reducing atmosphere to produce molten copper (hot water). The reducing atmosphere can be obtained, for example, by increasing the fuel ratio in a mixed gas of natural gas and air. More specifically, the CO concentration is set to the usual 0.5.
% To 5%, and oxygen concentration from normal 100 ppm to 2
It is about 0 ppm. As described above, since combustion is performed in the reducing atmosphere in the melting furnace A, the molten copper is subjected to the deoxidizing treatment.

The holding furnace B is for temporarily storing the hot water sent from the melting furnace A and sending the hot water to the casting gutter C while maintaining the temperature at a predetermined temperature. The casting gutter C transfers the hot water sent from the holding furnace B to the tundish 5 after sealing it in a non-oxidizing atmosphere. As shown in FIG. 2, the seal covers the upper surface of the molten copper flow path (flow path of molten copper) 31 of the casting gutter C.
This is done by covering with the cover 8. This non-oxidizing atmosphere is formed, for example, by blowing a mixed gas of nitrogen and carbon monoxide or a rare gas such as argon as an inert gas into the casting gutter C.

As shown in FIG. 2, the molten copper flow path 31 of the casting gutter C is provided with a stirring means (degassing means) 33 for performing a degassing treatment including a dehydrogenation treatment on the passing hot water. Have been. The stirring means 33 includes weirs 33a, 33b, 33
c, 33d so that hot water flows while being vigorously stirred.

The weir 33a is provided above the molten copper flow path 31, that is, on the cover 8. The weir 33b is provided below the molten copper flow path 31, the weir 33c is provided on the left side of the molten copper flow path 31, and the weir 33d is provided on the right side of the molten copper flow path 31.
By the weirs 33a, 33b, 33c, 33d, the hot water flows in the directions indicated by the arrows in FIG. 2 while meandering up, down, left, and right, and is agitated in a violent flow, whereby degassing can be performed. In addition, in FIG.
It is shown as 2. The weirs 33c and 33d are connected to the molten copper flow path 3
The length of the hot water flow path is made longer than the actual length, and even if the casting gutter C is short, the efficiency of the degassing process can be increased. The weirs 33a and 33b serve to prevent mixing of the molten copper and the atmosphere gas before and after the degassing process. The stirring means 33 is mainly for performing a dehydrogenation treatment. However, by stirring the hot water, oxygen remaining in the hot water can be expelled. That is, as degassing treatment, dehydrogenation treatment and 2
Both the second deoxygenation treatment is performed. These weirs 33
If a, 33b, 33c, and 33d are made of, for example, carbon, deoxygenation can be efficiently performed by contact between molten copper and carbon.

This degassing process needs to be performed in the transfer process after the holding furnace B. The reason is that, in order to obtain a low-oxygen copper ingot, in the holding furnace B, combustion of a reducing atmosphere or deoxidation treatment with a reducing agent is performed. To rise.

Further, the position where the degassing process is performed is as follows.
Degassing in the tundish 5 immediately before casting is also undesirable. The reason is that when the operation of the tundish 5 in which the hot water is vigorously stirred, for example, when bubbling is performed, the hot water surface vibrates violently, the head pressure of the hot water coming out of the pouring nozzle 9 fluctuates, and stable molten copper is formed. This is because it is not supplied to the continuous casting machine D. On the other hand, if the surface does not vibrate violently,
The effect of degassing cannot be expected. For this reason, it is preferable to perform the degassing process in the transfer process from the holding furnace B to the tundish 5.

The tundish 5 is provided with a pouring nozzle (not shown) at the end in the flow direction of the hot water, so that the hot water from the tundish 5 is supplied to the continuous casting machine D.

A continuous casting machine D is connected to the holding furnace B via a casting gutter C. The continuous casting machine D is a so-called vertical casting machine, and a casting copper material 2 having a predetermined cross-sectional shape is formed substantially vertically below while cooling the supplied molten copper.
The mold 41 and the pinch roll 42 are pulled out as 1
And The shape and arrangement of the mold 41 and the pinch roll 42 are appropriately selected according to the shape of the low oxygen copper ingot 23 obtained as a product. For example, when the low-oxygen copper ingot 23 is a billet having a substantially cylindrical shape, the mold 41 is made circular in section and the pinch roll 42 is formed.
Also have a shape corresponding to it. When the cake has a substantially rectangular parallelepiped shape, the mold 41 has a rectangular cross section, and the pinch roll 42 has a corresponding shape. In FIG. 1, a cake is shown as an example of the low oxygen copper ingot 23.

The cutting means E is for cutting the cast copper material 21 discharged from the continuous casting machine D to a predetermined length. An example of the cutting means E is a rotary cutter in which a disk-shaped blade rotates, but other configurations may be adopted as long as the cast copper material 21 can be cut.

The unloading means F includes a basket 51, an elevator 52, and a conveyor 53. The basket 51 is located almost immediately below the continuous casting machine D, receives the low-oxygen copper ingot 23 cut to a predetermined length by the cutting means E, and places it on the elevator 52. The elevator 52 carries the low-oxygen copper ingot 23 placed by the basket 51 to the position of the conveyor 53. The conveyor 53 transports the low-oxygen copper ingot 23 from the elevator 52, and is provided with a quality inspection device or a labeler (not shown) on the way. A turntable for changing the direction of the low-oxygen copper ingot 23 may be provided between the elevator 52 and the conveyor 53.

A method for producing a low-oxygen copper ingot using the low-oxygen copper ingot production apparatus 1 thus configured will be described. First, in a melting furnace A, combustion is performed in a reducing atmosphere, and molten copper is produced while deoxidizing the molten copper (a molten copper forming step). The deoxidized molten copper passes through the holding furnace B, is sealed in a non-oxidizing atmosphere using the casting gutter C, and is transported to the tundish 5 (molten copper transporting step). The molten copper deoxidized in the melting furnace A has a high hydrogen concentration because the oxygen concentration and the hydrogen concentration have an inverse relationship. The molten copper having the increased hydrogen concentration is dehydrogenated by the stirring means 33 when passing through the casting gutter C (degassing step).

Thus, the molten copper has an oxygen content of 20%.
ppm or less, and the content of hydrogen is adjusted to 1 ppm or less. By doing so, gas emission during casting is reduced, and the generation of holes in the cast copper material 21 can be suppressed. Further, from the relation of the equilibrium equation (A), since the gas concentration of the molten copper is reduced by lowering the partial pressure of steam, the molten copper before the dehydrogenation treatment is completely separated from the molten copper after the dehydrogenation treatment. This makes it possible to obtain a further degassing effect. This can be realized, for example, by providing the stirring means 33 as described above in the molten copper transfer step. That is, the stirring means 33 also serves to prevent mixing of the atmosphere gas before and after the dehydrogenation treatment and mixing of the molten copper.

After the molten copper transferred from the melting furnace A to the holding furnace B is heated, it is supplied to the continuous casting machine D via the casting trough C and the tundish 5. Then, it is pulled down from the mold 41 with a pinch roll 42, cooled and solidified, and continuously cast into the cast copper material 21 (continuous casting step).
The cast copper material 21 is cut by the cutting means E, and a low-oxygen copper ingot 23 having a predetermined length is sequentially and continuously manufactured (cutting step). The cut cast copper material 21 is carried out by the carrying-out means F as the low-oxygen copper ingot 23 (a carrying-out step). That is, the low-oxygen copper ingot 23 is received by the basket 51 located almost immediately below, placed on the elevator 52, carried up to the position of the conveyor 53, and conveyed by the conveyor 53. During this transportation, the low-oxygen copper ingot 23 is inspected for quality by a quality inspection device or an inspector, and the passed product is labeled with a product number or a lot number by a labeler. It can be shipped as lump 23.

In the apparatus for manufacturing a low-oxygen copper ingot and the manufacturing method using the same according to the present embodiment, combustion is performed in a reducing atmosphere in the melting furnace A, and the molten copper is deoxygenated. The molten copper is sealed in a non-oxidizing atmosphere in the casting gutter C and transferred to the tundish 5. Although the molten copper has a high hydrogen concentration because the oxygen concentration and the hydrogen concentration are in an inversely proportional relationship, the molten copper is dehydrogenated by the stirring means 33 in the subsequent degassing step. This makes it possible to reduce the hydrogen concentration, which increases as the deoxidizing treatment is performed by reduction, without securing a long transfer distance of the molten copper, thereby suppressing the generation of bubbles in the molten copper. Therefore, a high-quality low-oxygen copper ingot 23 in which generation of holes at the time of cooling and solidification is suppressed can be continuously produced in large quantities at low cost by using a gas furnace that performs combustion in the furnace.

Further, since the degassing means is the stirring means 33 for stirring the molten copper, the dehydrogenation can be forcibly performed in a short time, so that the dehydrogenation can be efficiently performed with a simple structure.

Further, if the stirring means 33 is constituted by a weir for meandering the flow path of the molten copper passing therethrough, it is automatically stirred by the flow of the molten copper itself, so that a special agitator or the like is not required. The dehydrogenation treatment can be performed efficiently with a simpler configuration, and the operation management of the low oxygen copper ingot manufacturing apparatus can be easily performed, so that the manufacturing can be performed at lower cost.

Incidentally, the separation by the stirring means 33 is not limited to one place, but may be appropriately set according to the length of the transfer process. Further, the low oxygen copper ingot is not limited to the low oxygen copper ingot throughout, and it is also possible to obtain a low oxygen copper alloy ingot by mixing an appropriate additive element. As the stirring means 33, weirs 33a, 33b, 33c, 33d are provided on the upper, lower, left, and right sides of the molten copper flow path 31, respectively, but the number and arrangement of these weirs are appropriately changed depending on the length and width of the casting gutter C. But it doesn't hurt.

Although a so-called vertical continuous casting machine D is used, a so-called horizontal continuous casting machine that performs continuous casting in the horizontal direction may be used. In this case, the elevating means such as the elevator 52 becomes unnecessary.

[0036]

As described above, according to the method and apparatus for producing a low oxygen copper ingot according to the present invention, degassing including dehydrogenation can be performed after deoxidizing molten copper. Therefore, using a gas furnace that burns in the furnace, dehydrogenation treatment can be performed without securing a long transfer distance, and high-quality low-oxygen copper ingots with suppressed generation of holes can be reduced. It can be mass-produced continuously at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically illustrating an apparatus for producing a low oxygen copper ingot according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part showing the casting gutter of FIG. 1 in a plan view (a) and a side view (b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus of low oxygen copper ingot 5 Tundish 21 Cast copper material 23 Low oxygen copper ingot 31 Molten copper flow path (Molten copper flow path) 33 Stirring means (Degassing means) 33a, 33b, 33c, 33d Weir A Melting furnace B Holding furnace C Casting gutter D Continuous casting machine E Cutting means F Unloading means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B22D 11/126 B22D 11/126 K 21/00 21/00 B 35/00 35/00 D 45/00 45 / 00 B C22B 9/16 C22B 9/16 F27D 3/14 F27D 3/14 A 23/04 23/04 (72) Inventor Kazumasa Hori 3-1-9 Chikko Shinmachi, Sakai City, Osaka Prefecture Mitsubishi Materials Corporation Inside Sakai Plant (72) Inventor Masahiko Wada 3-1-9 Chikko Shinmachi, Sakai City, Osaka Prefecture Mitsubishi Materials Corporation Inside Sakai Plant (72) Inventor Yoshiaki Hattori 3-1-9 Chikko Shinmachi, Sakai City, Osaka Mitsubishi Materials Real F-term in Sakai Plant Co., Ltd. (reference) 4E004 MB20 NC07 4K001 AA09 BA23 GA01 GA13 GB02 GB05 4K055 JA01 4K056 AA05 AA06 BA01 BB01 CA04 EA12 EA14

Claims (6)

[Claims] 1. A method for continuously producing a low-oxygen copper ingot from molten copper, comprising: a molten copper producing step of producing molten copper by burning a melting furnace in a reducing atmosphere; Transferring the molten copper sent from the vessel to the tundish using a casting gutter that can be sealed in a non-oxidizing atmosphere, and performing a dehydrogenation treatment on the molten copper passing through the casting gutter. A gas process; a continuous casting process of continuously producing a cast copper material by supplying the molten copper to a continuous casting machine; and a cutting process of cutting the cast copper material into a predetermined length to form a low oxygen copper ingot. A method for producing a low-oxygen copper ingot, comprising: 2. The method for producing a low oxygen copper ingot according to claim 1, wherein in the degassing step, a dehydrogenation treatment is performed by stirring the molten copper. 3. The method for producing a low-oxygen copper ingot according to claim 2, wherein said stirring means performs stirring by meandering the flow path of the passing molten copper. 4. A production apparatus for continuously producing a low-oxygen copper ingot from molten copper, comprising: a melting furnace for producing molten copper by burning in a reducing atmosphere; and a melting furnace sent from the melting furnace. A holding furnace for holding copper at a predetermined temperature, a casting gutter for sealing the molten copper sent from the holding furnace in a non-oxidizing atmosphere and transferring the molten copper to a tundish, and dehydrating molten copper provided in the casting gutter. Degassing means for elementary treatment, a continuous casting machine for continuously producing a cast copper material from molten copper supplied from the tundish, and cutting means for cutting the cast copper material to a predetermined length. An apparatus for producing a low oxygen copper ingot. 5. The apparatus for producing a low oxygen copper ingot according to claim 4, wherein the degassing means is a stirring means for stirring the molten copper. 6. The apparatus for producing a low oxygen copper ingot according to claim 5, wherein said stirring means is constituted by a weir for meandering the flow path of said passing molten copper.