JP2003253351A - Process for producing highly pure copper from hydrous impure copper powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing highly pure copper from a hydrous impure copper powder containing chlorine compounds and oxides of copper, such as deteriorated copper etchant generated upon etching a copper-clad laminate. <P>SOLUTION: A highly pure copper ingot is produced by charging the hydrous impure metallic copper powder which contains chlorine compounds of copper and has an average grain size of ≤500 μm into a furnace, coating its surface with carbon or a carbon-containing substance and heat treating it at 1,083-1,300°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing high-purity copper from hydrous impure copper powder containing at least chlorine compounds such as copper recovered by electrolysis from a deteriorated copper etching solution. More specifically, the copper-clad laminate is etched to form a circuit conductor and contains at least a chlorine compound such as copper recovered from a deteriorated copper etching solution generated when a printed wiring board is manufactured, and the water content is about 30 wt%. The present invention relates to a method for producing a high-purity copper ingot from water-containing impure copper powder having a small particle size.

[0002]

2. Description of the Related Art A printed wiring board used by being incorporated into an electronic device or the like has various copper clad laminates obtained by laminating and adhering a copper foil as a circuit conductor material and a resin base material as an insulating material. Is used. To form a desired circuit conductor from this copper-clad laminate, the copper-clad laminate is etched by bringing it into contact with a copper etching solution, for example, a cupric chloride-hydrochloric acid aqueous solution to dissolve and remove unnecessary copper other than the circuit conductor. To do.

When this etching is repeated, cuprous chloride is formed in the copper etching solution, its concentration gradually increases, the etching function deteriorates, and it becomes difficult to maintain proper etching. Therefore, it has been conventionally known that cupric chloride is made to regenerate into cupric chloride by acting an oxidizing agent such as hydrogen peroxide solution. It is also known to recover copper as metallic copper by electrolysis from a deteriorated etching solution having an increased copper concentration.

For example, JP-A-51-23447 discloses a method in which a deteriorated etching solution is electrodeposited with metallic copper by a diaphragm electrolysis method, and JP-A-56-17429 discloses a deteriorated copper chloride etching method. Method for regenerating liquid by electrolytic method and recovering metallic copper, JP-A-2-25418
Japanese Patent Laid-Open No. 8 proposes a method of oxidizing a solution containing cuprous chloride to convert it to cupric chloride to regenerate a deteriorated etching solution and depositing metallic copper on the cathode.

It is important to deposit copper, which is a valuable metal, from a deteriorated copper etching solution as in these proposals and use it as a copper material because it is excellent in terms of resource reuse (recycling). It is becoming visible. Under such circumstances, there have been many proposals for improved techniques for copper electrodeposition, and the inventors of the present invention have conducted extensive research and development on these and applied for a patent for the results.
The technology disclosed in that application is disclosed in Japanese Patent Laid-Open No. 5-11787.
No. 9, JP-A-5-125564, and JP-A-6-
No. 158359, or Japanese Patent Laid-Open No. 2001-1072
There are 70 publications and the like.

Among these techniques, Japanese Patent Laid-Open No. 6-1583
JP-A-59-59 provides an electrolytic cell which makes it possible to regenerate a deteriorated etching solution in a closed process that does not release chlorine externally, and copper deposited at that time is scraped off from an electrode. to recover. Also in the above-mentioned Japanese Patent Laid-Open No. 2001-107270, which provides an improved electrolytic regeneration treatment system proposed by the present inventors thereafter, copper deposited on the cathode is scraped and collected from the electrode, and the collected copper is It is a powder.

The recovered powder of copper is electrolyzed in a solution containing hydrochloric acid, and is deposited in the hydrochloric acid-containing electrolytic solution until it is intermittently taken out of the electrolytic cell to the outside. . Therefore, the powdered copper contains the first chloride
Chlorine compounds such as copper, cupric chloride and hydrochloric acid, oxides such as cuprous oxide, copper oxide and copper hydroxide, or various compounds such as chlorine adhere to the surface and have a high water content. Therefore, it is difficult to use the recovered metallic copper as it is as a copper ion source copper material for producing a printed wiring board electrolytic copper foil, for example, as it is.

[0008] Specifically, the disadvantage is that the chlorine compound adhering to the surface of the recovered copper material exists as chlorine ions in the copper plating solution, and chlorine gas is generated from the anode during electrolysis, resulting in electrolytic copper. Corrosion and wear of foil manufacturing equipment, for example, equipment such as anode material, cathode material and electrolytic cell. In addition, the chlorine gas generated pollutes the environment and is extremely harmful to health. Furthermore, discoloration of the copper foil surface in terms of the quality of the copper foil,
It causes corrosion.

As described above, when the metal copper recovered by electrodeposition is used as a recycled material, it contains no chlorine or a trace amount of chlorine that does not adversely affect the physical properties of the copper foil. It was difficult to use when required. Therefore, a method for producing high-purity copper refined from the recovered powder metal copper has already been proposed, and for example, there is a technique disclosed in JP-A-11-335752.

The method described in this publication is (1) a step of electrolyzing a copper etching waste liquid to recover chlorine-containing copper deposited on the cathode, and (2) dechlorination by melting the recovered chlorine-containing copper at a high temperature. And (3) a step of bringing molten copper that has been dechlorinated into contact with water and rapidly cooling it to form granular copper. As described above, this method has a high temperature melting step and a rapid cooling step, and there is room for further improvement in terms of energy economy.

Furthermore, it is difficult to say that the purity or yield of the produced copper is sufficiently satisfactory according to the results of additional tests by the present inventor, and further improvement in these points is desired. Met. That is, if the average particle size exceeds 500 μm, this method will work effectively, but the average is 500 μm or less, especially 100 μm.
Below m, a large amount of copper oxide remained in the granular copper, resulting in low purity and poor yield.

[0012]

As a result, the present inventor also contains at least the chlorine compound of copper such as cuprous chloride and cupric chloride, and the copper compound such as copper oxide and copper hydroxide is contained. The present invention has been successful in the research and development in order to develop a technique for producing high-purity copper from a water-containing impure copper powder having a small particle size that may contain various impurities such as oxides, and as a result, the present invention succeeded in the development. is there. Therefore, the present invention is to provide a method for producing high-purity copper from a water-containing impure copper powder having a small particle size and containing at least a chlorine compound such as copper recovered by electrolysis from a deteriorated copper etching solution. To do

[0013]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing high-purity copper, which comprises at least a water-impure metallic copper powder containing a chlorine compound of copper and having an average particle size of 500 μm or less. Is introduced into the furnace, the surface is covered with carbon or a carbon-containing substance, and the temperature is 1083 ° C or higher and 1300 ° C
It is characterized in that it is heat-treated below.

The impure hydrous copper powder, which is a raw material for producing copper of the present invention, is typically electrolyzed in a solution containing hydrochloric acid, and until it is intermittently taken out of the electrolytic cell to the outside, it contains hydrochloric acid. Since it is deposited and deposited in the electrolytic solution, the surface of the copper powder has a chlorine compound such as cuprous chloride, cupric chloride, hydrochloric acid, copper oxide such as copper hydroxide and copper oxide, or chlorine. It is covered with various impurities and has a water content of about 3
It is as high as 0 wt%.

In the present invention, such a small particle size hydrous impure metal copper powder is put in a furnace, the surface is covered with carbon or a carbon-containing substance, and the copper powder is heated at a high temperature to melt the copper powder. A copper ingot of high purity can be obtained. Since it is as described above, there is no reducing agent in the copper powder, nevertheless, since a high-purity ingot is obtained,
It is speculated that when heated at a high temperature, the water vaporizes and the copper chlorine compound also volatilizes or thermally decomposes.

As a result, it is speculated that the remaining undecomposed copper chloride, oxide, etc. are separated from copper by the difference in specific gravity due to this volatilization or increase in decomposition gas, and a high-purity copper ingot is obtained. ing. Further, if the water-impure metal copper powder surface is not covered with carbon or a carbon-containing substance, a high-purity copper ingot cannot be obtained, and since it becomes an ingot in which copper oxide is mixed, carbon or a carbon-containing substance,
It is presumed that it inhibits the invasion of oxygen into the copper powder.

The copper thus obtained has a high purity, a low chlorine content, and a high purity that can be used as a copper material for forming a copper foil. Also,
The manufacturing process is simple because it only requires high-temperature heat treatment using carbon or a carbon-containing substance, and the equipment is simple.It is also possible to carry out the method of the present invention in the same factory as the etching treatment. It is possible. Therefore, the present invention is excellent because it contains a chlorine component, and has a high water content, and as a result, it is difficult to handle, the transportation cost is high, and the copper powder recovered from the deteriorated etching solution can be treated without moving. Is the way.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The method for producing high-purity copper of the present invention comprises charging a furnace with water-impure metal copper powder having an average particle diameter of 500 μm or less containing at least a chlorine compound of copper, and covering the surface thereof with carbon or a carbon-containing substance, 1083 ° C or higher, 1300 ° C
It is characterized in that it is heat-treated below.

Regarding the water-impure metallic copper powder as a raw material,
It is not limited to scraped copper deposited by electrolysis, and has an average particle size of 500 μm or less and contains a chlorine compound of copper such as cuprous chloride and cupric chloride and water. If it is, it can be used without particular limitation. Further, the impure water-containing copper metal powder may contain various impurities such as copper oxide or copper hydroxide other than the chlorine compound of copper.

In such a water-impure metal copper powder, a copper-clad laminate is etched to form a circuit conductor to electrolyze a deteriorated copper etching solution which is produced when a printed wiring board is manufactured, and deposited copper is scraped off. One example is the one collected and collected. Similarly, an etching solution used for etching a laminated plate, which is a hydrous impure metal copper powder recovered by electrolyzing a deteriorated ferric chloride etching solution containing copper dissolved after use, can be exemplified.

In the present invention, the impure metal copper powder is not limited to the one obtained by electrolysis as described above, but the one obtained by scraping the deposited copper and collecting it can be preferably used. The technique for producing the copper powder is disclosed in the above-mentioned JP-A-6-158359, JP-A-2001-107270, JP-A-11-335752, etc., which have been developed by the present inventors. They can be used in the invention.

In particular, in order to obtain the impure water-containing copper metal powder used as a raw material in the present invention, the structure or material of the electrolytic cell having a diaphragm described in the Japanese Patent Laid-Open No. 6-158359 developed by the present inventors. Etc. can be preferably used. Specifically, regarding the electrolytic cell, the cathode, the anode, the diaphragm, the electrolytic treatment liquid, the operating conditions, etc., the items described in the publication can be adopted. For more specific operating conditions, see Japanese Patent Laid-Open No. 11-3
It is disclosed in Japanese Patent No. 35752, and this can be used.

The impure metallic copper powder thus recovered is electrodeposited and scraped in a deteriorated etching solution such as cupric chloride or ferric chloride solution, and taken out from the electrolytic cell to the outside. . Since the taking out is performed intermittently, the copper powder is settled and deposited in the electrolytic solution in which hydrochloric acid and a chlorine compound coexist. Therefore, metallic copper powder taken out from the electrolytic cell is mixed with cuprous chloride, cupric chloride, chlorine compounds such as hydrochloric acid, cuprous oxide, copper oxide, copper hydroxide or copper carbonate, and has a water content. Is as high as about 30 wt%. Average particle size 500μ recovered in this way
Those having a size of m or less can be used as the raw material of the present invention.

The impure metal copper powder used as the raw material of the present invention is required to have an average particle size of 500 μm or less. If the average particle size is larger than 500 μm, it is put into the furnace as it is and heated to a high temperature. It is possible to produce a high-purity copper ingot for a while even if it is heat-treated, and because the particle size is large, it is easy to wash and it is also possible to produce a high-purity copper ingot by heating after the washing treatment. is there. The average particle size of the copper powder is 100 μm.
The present invention can be preferably applied to the following.

The water content is preferably as low as possible, but it is not particularly necessary to reduce it by centrifugation or the like.
The one taken out of the electrolytic cell can be used as it is. Further, the impurities attached to the surface of the metal copper powder do not need to be reduced particularly by washing with water, as in the case of water.

Regarding carbon or a carbon-containing substance (hereinafter, sometimes referred to as a surface coating material) which covers the surface of the impure water-containing copper metal powder, the gas generated in the furnace during the high temperature heat treatment in the furnace can be passed through. Any material can be used without particular limitation as long as it can prevent the invasion of oxidizing gas such as air into the copper powder. That is, if an oxidizing gas is converted to a non-oxidizing gas or reacts with the surface coating material to be trapped when the oxidizing gas is about to pass, as long as the oxidizing gas can be prevented from entering the copper powder. Well, it is preferably powdery or granular.

Examples of the carbon include charcoal, bamboo charcoal, and waste activated carbon. Further, as the carbon-containing substance, felled wood bamboo, waste wood or waste plastic can be exemplified, and as for waste plastic, various waste waste plastics can be used without limitation, including polyethylene, polypropylene,
Waste materials such as polystyrene, polyvinyl acetate, and polyvinyl alcohol can be exemplified.

The heat treatment of the impure metallic copper powder is 1083 ° C.
As described above, it is necessary to perform the treatment at a high temperature of 1300 ° C. or lower, and by treating at such a high temperature, copper oxide, hydroxide and chloride are partially reduced or thermally decomposed,
It is understood that most of them are separated from copper by the difference in specific gravity. The furnace used for heat treatment at this high temperature is not particularly limited as long as it is a heat-resistant furnace, and there are a resistance heating electric furnace, an induction heating furnace, a combustion furnace, a kiln, etc., but an induction furnace or the like can be used. is there.

As the refractory material used in the furnace, the heat treatment of the impure metal copper powder in the present invention is required to be carried out at 1083 ° C. or higher and 1300 ° C. or lower, and at least the refractory material in that range is required. is necessary. Therefore, as refractory materials, chromium-magnesia refractory,
A furnace material for copper or a copper alloy such as a carbon bond graphite-based refractory can be exemplified. It is necessary to carry out the reduction within the above temperature range because the melting temperature of copper is 1083 ° C.

The impregnation of the impure metallic copper powder into the furnace may be carried out in the open air, whereby air remains in the gaps between the impure metallic copper powder. Further, the charging of the surface coating material into the furnace needs to be placed on the copper powder so as to cover the surface thereof. According to the present invention, a high-purity copper ingot can be produced in this way without leaving various compounds of copper or unreacted carbon or carbon-containing substances in the copper ingot.

In the present invention, the technical reason for producing such a high-purity copper ingot has not been elucidated as described above, but it is presumed as follows. That is, a high-purity copper ingot is obtained by placing water-impure metallic copper powder in a furnace, covering the surface with carbon or a carbon-containing substance, and then heating at high temperature to melt the copper powder.

At that time, a high-purity ingot was obtained even though no reducing agent was present in the copper powder.
From this, it is presumed that the water content evaporates as the temperature rises, and the chlorine compound of copper also volatilizes or thermally decomposes. As a result, the remaining undecomposed copper chloride or oxide, etc. is separated from copper by the difference in specific gravity due to the rise of this volatilization or decomposition gas in the furnace, and the molten copper is at the bottom of the furnace.
It is presumed that undecomposed copper oxide and the like move to the upper part to obtain a high-purity copper ingot.

Further, when the surface of the impure water-containing copper metal powder is not covered with carbon or a carbon-containing substance, a high-purity copper ingot cannot be obtained, and an ingot containing copper oxide is present. Speculate that it inhibits the invasion of oxygen into the copper powder. It should be noted that carbon or a carbon-containing substance exists in the furnace, and there is also a small amount of residual air at the time of charging the copper powder, so that reducing gas is generated, and whether the copper compound is reduced by it Has not been confirmed at present.

For this heat treatment, it is preferable that a melting aid and an oxygen scavenger are present in the hydrous impure metal copper powder. The former melting aid can form a eutectic with a copper oxide component having a melting point higher than that of copper present on the surface of the metallic copper powder, thereby lowering the melting point of copper oxide that inhibits melting of copper inside. be able to. As a result, it is possible to avoid unmelted copper powder in the ingot and lumps of copper oxide due to being covered with copper oxide having a high melting point.

As such a melting aid, sodium carbonate, potassium carbonate, calcium carbonate, silica sand or borax can be used. This melting aid can also be used by placing it on copper powder in combination with carbon or a carbon-containing substance. In that case, during heat treatment, oxygen may enter the copper powder to oxidize copper. Can be stopped.

The latter oxygen scavenger can produce a higher purity copper ingot in which the oxygen concentration in the produced copper ingot is reduced. As the oxygen scavenger, red phosphorus or phosphoric acid can be preferably used. In this way, as an oxygen scavenger,
When red phosphorus or phosphoric acid is used, a small amount of phosphorus can remain in the produced high-purity copper, and in that case, a copper containing a small amount of phosphorus can be reused for copper plating. Is particularly preferable because it is preferable. Yellow phosphorus also has a deoxidizing ability, but it is highly toxic and dangerous when used.

[0037]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples, but the present invention is not limited to these Examples and is specified by the scope of claims. It goes without saying that it is a thing.

[Example 1] Copper 51.7 wt%, chlorine 6.7
700 g of copper powder having an average particle diameter of 75 μm and containing about 30 wt% of water and about 30 wt% of water was placed in a crucible of silica-alumina-based refractory material having an inner volume of about 380 ml, and 21.5 g of granular carbon as a surface coating material was placed thereon. It was added so as to cover the copper powder.
Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours.
The heating temperature is a temperature in the furnace space measured by a K thermocouple.

After heating, the contents were taken out from the crucible to obtain 273 g of a copper ingot. When the components of the ingot were analyzed, Cu> 99.5 wt% and chlorine 20 mg / kg. For other trace impurities,
Sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the raw material copper powder was 75 wt%.

Example 2 Copper 51.7 wt%, chlorine 6.7
700 g of copper powder having an average particle size of 75 μm containing wt% and water of about 30 wt% was mixed with 7 g of 85% phosphoric acid aqueous solution, and the mixture was placed in a crucible made of silica-alumina refractory material having an internal volume of about 380 ml, and a surface coating was performed thereon. Granular carbon as a material 19.5
g was added so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours.

After heating, the contents were taken out from the crucible to obtain 295 g of a copper ingot. When the components of the ingot were analyzed, it was found that Cu> 99.5 wt%, chlorine 21 mg / kg, and phosphorus 0.277 wt%. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the raw material copper powder is 8
It was 1.1 wt%.

Example 3 Copper 49.9 wt%, chlorine 5.3
0.96 g of red phosphorus was mixed with 700.38 g of copper powder having an average particle size of 75 μm containing 1 wt% and about 36 wt% of water, and the mixture was placed in a crucible of silica-alumina refractory material having an internal volume of about 380 ml. 20 g of granular carbon as a surface coating material
Was added so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours.

After heating, the contents were taken out from the crucible to obtain 295 g of a copper ingot. When the components of the ingot were analyzed, it was found that Cu> 99.5 wt%, chlorine 24 mg / kg, and phosphorus 0.146 wt%. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the raw material copper powder is 8
It was 4 wt%.

[Example 4] Copper 50.8 wt%, chlorine 6.0
75μ average particle size containing 8wt% and about 31.7wt% water
710.4 g of copper powder of m was mixed with 4.49 g of borax,
It was placed in a crucible made of silica-alumina-based refractory material and having an internal volume of about 380 ml.
4.9 g was added so as to cover the copper powder. Then, load the crucible into the electric furnace and raise the temperature inside the furnace to 1100 ° C in 1.17 hours.
The temperature was raised to and maintained at the same temperature for 2 hours.

After heating, the contents were taken out from the crucible to obtain 300.71 g of a copper ingot. When the composition of the ingot was analyzed, Cu> 99.5 wt
%, Chlorine 19 mg / kg. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the copper powder used as the raw material was 82.9 wt%.

[Example 5] 50 wt% of copper and 7.01 w of chlorine
75% copper powder having an average particle size of 75 μm containing t% and about 37% water
1.19 g of sodium carbonate and 1.17 g of potassium carbonate were mixed with 1.9 g, and the mixture was put into a crucible made of silica-alumina-based refractory material having an internal volume of about 380 ml. 1 g was added so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1100 ° C. in 1.17 hours, and the same temperature was maintained for 2 hours.

After heating, the contents were taken out from the crucible to obtain 325.05 g of a copper ingot. When the composition of the ingot was analyzed, Cu> 99.5 wt
%, Chlorine 17 mg / kg. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the copper powder used as the raw material was 86 wt%.

[Example 6] Copper 52.7 wt%, chlorine 6.3
Copper powder 7 with an average particle size of 75 μm containing wt% and water of about 34%
50.79 g was mixed with 2.33 g of calcium carbonate,
It was placed in a crucible made of silica-alumina refractory material and having an internal volume of about 380 ml, and granular carbon 8 was placed thereon as a surface coating material.
g was added so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1100 ° C. in 1.17 hours, and the same temperature was maintained for 2 hours.

After heating, the contents were taken out from the crucible to obtain 326.95 g of a copper ingot. When the composition of the ingot was analyzed, Cu> 99.5 wt
%, Chlorine 24 mg / kg. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the raw material copper powder was 82.2 wt%.

Example 7 Copper 47.4 wt% and chlorine 5.0
350 g of copper powder having an average particle size of 75 μm containing 1 wt% and water of about 35% was mixed with 10 g of sodium carbonate and put in a crucible made of dense alumina with an internal volume of about 200 ml, and 20 g of charcoal as a surface coating material was placed on the crucible. It was added so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours.

After heating, the contents were taken out from the crucible, and 159.6 g of a copper ingot was obtained. When the components of the ingot were analyzed, Cu> 99.5 wt%,
It was 20 mg / kg of chlorine. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the raw material copper powder was 95.7 wt%.

[Example 8] 47.4 wt% of copper and 5.0 of chlorine
350 g of copper powder having an average particle diameter of 75 μm containing 1 wt% and about 35% of water is mixed with 10 g of calcium carbonate, and the mixture is put into a crucible made of dense alumina and having an inner volume of about 200 ml, on which 20 g of charcoal as a surface coating material is placed. It was added so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours.

After heating, the contents were taken out from the crucible, and 159.4 g of a copper ingot was obtained. When the components of the ingot were analyzed, Cu> 99.5 wt%,
It was 20 mg / kg of chlorine. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the copper powder used as the raw material was 95.6 wt%.

[Example 9] 44.4 wt% of copper and 3.8 of chlorine
438.79 g of copper powder having an average particle size of 75 μm and containing 1 wt% and about 37% of water was mixed with 10 g of calcium carbonate, and the mixture was put into a crucible made of dense alumina and having an inner volume of about 200 ml.
On top of that, 20 g of waste plastic, which was a composite of glass fiber and epoxy resin, was placed as a surface coating material so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours.

After heating, the contents were taken out from the crucible to obtain 191.7 g of a copper ingot. When the components of the ingot were analyzed, Cu> 99.5 wt%,
It was 40 mg / kg of chlorine. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the raw material copper powder was 97.9 wt%.

[Example 10] 44.4 wt% of copper and 3.8 of chlorine
Copper powder 45 having a particle size of 75 μm and containing 1 wt% and about 37% water
3.02 g was put in a crucible made of dense alumina and having an inner volume of about 200 ml, and 20 g
g was added so as to cover the copper powder. Next, the crucible was charged into an electric furnace, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours. In Examples 7 to 10, the melting aid was present, but the temperature was raised to 1200 ° C.

After heating, the contents were taken out from the crucible to obtain 180.56 g of a copper ingot. When the composition of the ingot was analyzed, Cu> 99.5 wt
%, Chlorine 20 mg / kg. As for other trace impurities, sulfur, iron, silicon, etc. were detected. The yield of pure copper contained in the copper powder used as the raw material was 89.8 wt%.

[Comparative Example 1] Copper 56.6 wt%, chlorine 8.8
700 g of copper powder containing wt% and about 30 wt% of water was put into a crucible made of dense alumina and having an inner volume of about 200 ml.
Then, the crucible was charged into an electric furnace without using a surface coating material or the like, the temperature inside the furnace was raised to 1200 ° C. in 1.17 hours, and the temperature was maintained for 2 hours. After the heating was completed, a porous mass was formed in the crucible. The lump adhered to the crucible and could not be taken out without destroying the crucible. A part of the sample was forcibly sampled and quantitatively analyzed. As a result, copper was 90.3 wt% and chlorine was 4 wt%, and a large amount of insoluble components in nitric acid was present.

[0059]

The method for producing high-purity copper according to the present invention is 30 w.
It contains about t% of water, contains at least a chlorine compound of copper such as cuprous chloride and cupric chloride, and contains various impurities such as oxides of copper such as copper hydroxide and copper oxide. It is possible to produce high-purity copper only by heat-treating it at a high temperature in a small furnace using inexpensive carbon or a carbon-containing substance without dehydration in advance from impure water-containing impure copper powder covered with good impurities. It is a thing. Therefore, the treatment is simple and no special equipment is required.

The obtained copper has a high purity, a low chlorine content, and a purity that allows it to be used as a copper material for forming an etching solution. Further, the treatment process and equipment are simple and simple as described above, and it is also possible to easily install equipment therefor in the etching factory. Therefore, it contains a chlorine component and hydrochloric acid that is a strong acid, and has a high water content, and as a result, it is difficult to handle, and the transportation cost is high. Since copper powder can be treated without moving, the present invention is an excellent method. is there.

Claims (5)

[Claims] 1. A water-impure metallic copper powder containing at least a chlorine compound of copper and having an average particle size of 500 μm or less is introduced into a furnace, and the surface thereof is covered with carbon or a carbon-containing substance.
A method for producing high-purity copper, characterized by performing heat treatment at 3 ° C or higher and 1300 ° C or lower. 2. The method for producing high-purity copper according to claim 1, wherein the water-impure metal copper powder is obtained by electrolyzing an aqueous solution containing copper chloride and scraping off the copper deposited on the electrodes. 3. The method for producing high-purity copper according to claim 1, wherein the carbon or the carbon-containing substance is charcoal, bamboo charcoal, felled wood bamboo, waste wood, waste activated carbon, or waste plastic. 4. The method for producing high-purity copper according to claim 1, wherein sodium carbonate, potassium carbonate, calcium carbonate, silica sand or borax is used as the melting aid. 5. The method for producing high-purity copper according to claim 1, wherein red phosphorus or phosphoric acid is used as the oxygen scavenger.