JPH0885830A - Method for peeling plating from surface of copper or copper alloy - Google Patents

Abstract

PURPOSE: To easily and efficiently peel an Ni-base or Ag-base plating layer from Cu or Cu-base alloy by heating Cu or Cu-base alloy, having an Ni-base or Ag-base plating layer, up to specific temp. in an oxidizing atmosphere. CONSTITUTION: The waste articles of metallic parts of Cu or Cu-Fe alloy, etc., having a plating layer of Ni-base metal or Ag-base metal on the surface, are heated to 700-1000 deg.C for 3-20min in a heating furnace with oxidizing atmosphere. A layer of copper oxide of extremely brittle material is formed in the boundary zone between the base metal of Cu or Cu-Fe alloy, etc., and the Ni-base or Ag-base plating layer, and the Ni-base plating layer or the Ag-base plating layer can be easily peeled and removed from Cu or Cu-Fe. By this method, the waste articles of Cu or Cu alloy such as Cu-Fe can be recovered and reused as Cu or Cu-Fe alloy in a quality excellent in value in reclaimed use, free from plating metal, such as Ni and Ag.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for efficiently peeling and removing a Ni-based or Ag-based plating layer from a recovered copper or copper alloy product having a Ni-based or Ag-based plating layer formed on its surface by a simple treatment. It is about.

[0002]

2. Description of the Related Art Copper or a copper-based alloy (hereinafter referred to as a copper alloy) is widely used as a base material for heat exchangers, electronic component materials, etc. because it has excellent heat conductivity and electric conductivity and good workability. Although they are used, their reserves are extremely small compared to iron, and the recovery and reuse of waste copper alloy products is extremely important from the viewpoint of resource and energy conservation.

By the way, copper alloy products used for electronic parts and the like may be subjected to various metal plating treatments for various purposes. However, the plated metal is mixed as impurities in the recovered copper alloy product and has physical properties. Must be removed as much as possible because it may significantly damage the. Typical of such plated metals is Ni-based plating coated on the surface of copper-iron alloy products used for electronic component materials.
It becomes a -Fe-Ni alloy melt and cannot be reused as the original Cu-Fe alloy.

Therefore, in order to reuse the remelted product as a Cu-Fe alloy raw material, it is necessary to remove Ni from the molten metal, but it is difficult to successfully remove only Ni from the molten metal. As a method for removing Ni contained in a copper alloy melt containing no Fe, there is known a melting and refining method in which iron oxide is added to the melt and the Fe-Ni-based complex oxide is removed. However, this method can remove Ni efficiently, but at the same time as Fe in the refining process,
Since it is also oxidized, the Fe content of the molten metal changes significantly, and it cannot be regenerated as the original Cu-Fe alloy. Therefore, the oxidative refining method as described above is applied to a copper alloy substrate containing an alloying element having a high reactivity with oxygen, such as Fe, for example.
It cannot be applied to remove Ni from a system-plated recovered product. In addition, depending on the use of the copper alloy product, its surface may be subjected to Ag-based plating. In this case, the dissolved substance of the recovered product contains Ag as an impure element, but Ag is more oxidized than copper. Since it is an element that is stable against, it cannot be removed from the copper alloy melt by the oxidation refining method.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and its purpose is to select a metal having a high reactivity with oxygen such as Fe. Ni or Ag is recovered from the recovered product in which the surface of the copper alloy product contained as an alloying element is plated with Ni or Ag.
The present invention is intended to provide a method capable of efficiently removing the above by a simple method.

[0006]

The constitution of the plating stripping method according to the present invention which has been able to solve the above-mentioned problems is to oxidize copper or a copper-based alloy having a Ni-based or Ag-based plated layer formed on its surface. It is heated in an atmosphere to form a brittle layer of copper oxide at the boundary between the copper or copper-based alloy and the Ni-based or Ag-based plated layer, and then the Ni-based or Ag-based plated layer is peeled and removed. I have. The preferable conditions of the above heating are 700 to 1000 ° C. and 3 to 2
It is in the range of 0 minutes, and the plating layer can be almost completely removed by peeling and removing the Ni-based or Ag-based plated layer while cooling after the heat treatment or after cooling.

[0007]

As described above, according to the present invention, copper or a copper-based alloy (hereinafter, referred to as
Again referred to as a copper alloy) in an oxidizing atmosphere to form a brittle layer of copper oxide at the boundary between the copper alloy substrate and the Ni-based or Ag-based plated layer, and then form the Ni-based or Ag-based plated layer. The structure of the present invention is to be removed efficiently by removing the solid state, and the structure of the present invention will be described in detail with reference to the circumstances that led to such a structure.

First, 1000, which is a temperature below the melting point of copper
Comparing the standard free energy of formation of each oxide of Ni and copper under the temperature condition of C, the standard free energy of formation of Ni oxide is −124 kJ / mol · O ₂ , whereas the standard free energy of formation of Cu oxide is -74kJ /
Since it is mol · O ₂ and Ni has a stronger oxidizing power than Cu, when a copper alloy having Ni-based plating on the surface is heated in an oxidizing atmosphere, oxidation of the Ni-based plating on the surface proceeds. The oxidation of copper is promoted by oxygen that diffuses and migrates toward the copper alloy base material through the plating layer, and copper oxide is generated at the interface between the plating layer and the copper alloy base material, but this copper oxide is very fragile. It was confirmed that the formation of the brittle copper oxide allows the plating layer to be easily peeled and removed from the copper alloy substrate.

Incidentally, in order to confirm the above-mentioned oxidation phenomenon, FIG. 1 uses a copper alloy containing 1% by weight of Fe as a base material,
It is a graph showing the results of thermal analysis of a material whose surface is plated with 0.8% by weight of Ni, and as is clear from this figure, the weight increase due to the oxidation of the Ni-plated Cu-Fe alloy is about 700. Starting from around the temperature exceeding 0 ° C, the weight increase amount increases as the temperature rises, and it is possible to confirm the absorption of oxygen, that is, the progress of oxidation. And
When the Ni plating layer on the surface of the test material is peeled off after the oxidation is performed in this manner, the plating layer can be peeled off from the base material very easily, and brittle copper oxide is generated on the peeled surface. Was confirmed.

That is, the present invention utilizes such a phenomenon,
A Ni-plated copper alloy material is heat-treated in an oxygen-containing gas atmosphere to form a brittle layer made of copper oxide at the interface between the Ni-plated layer and the base material, and then the brittle layer is used as a boundary. The feature is that the Ni-based plating layer is peeled and removed. Therefore, in this heating and oxidation step, it is necessary to form copper oxide between the base material and the Ni plating layer. For that purpose, the heating temperature is preferably about 700 ° C. or higher, the heating time is about 3 minutes or longer, and Preferably, it is set to about 5 minutes or more. However, if this heating and oxidization proceeds excessively, the amount of consumption of the copper alloy as the base material due to oxidation increases and the yield of copper or copper alloy decreases, so the heating and oxidation time is about 20 minutes or less, More preferably, it is desired to be suppressed to 15 minutes or less. The upper limit of the heat treatment temperature is a temperature at which the copper alloy base material does not melt, but is usually 1
Since oxidation proceeds sufficiently at about 000 ° C, it is desirable to suppress the temperature to about 1000 ° C or less, more preferably to about 900 ° C or less in consideration of workability and thermal efficiency.

By the way, FIGS. 2 and 3 use the same Ni-plated Cu-1% Fe alloy as that used in the experiment of FIG.
A molten metal obtained by heating and oxidizing the Ni plating layer in a process as shown in FIG. 4 and then removing the Ni plating layer by heating and melting in an induction melting furnace. It is a graph showing the result of examining the Ni concentration in the inside. In FIG. 4, 1 is a rotary resistance heating furnace, 2 is a vibrating sieve, 3 is an induction melting furnace, and the test material A is charged into the rotary resistance heating furnace 1 which is open to the atmosphere, and at a predetermined temperature. After heating and oxidizing for a predetermined time, the Ni plating layer is peeled and removed by passing through a vibrating screen 2 with an air cooler, and then heated and melted in an induction melting furnace 3. Then, the molten metal was sampled to quantify the residual Ni concentration.

As is apparent from FIGS. 2 and 3, the temperature of the heat oxidation treatment is 700 to 1000 ° C. and the heating time is 5 to 1
It can be seen that the Ni plating layer can be removed efficiently by removing the Ni plating layer for 5 minutes. Table 1 shows the results of examining the influence of the heating temperature and the heating time on the Cu yield. Particularly, when the heating temperature exceeds 600 ° C., the Cu yield increases when the heating time exceeds 20 minutes. Decrease significantly, and also when the heating temperature exceeds 900 ° C, the Cu yield obviously decreases, so the heating time is 20 minutes or less, more preferably 15 minutes or less, and the heating temperature is about 900 ° C. It is desirable to keep the amount below.

[0013]

[Table 1]

By the way, as described above, the copper alloy substrate and Ni
Since the copper oxide formed on the boundary surface with the system plating layer is extremely brittle as described above, the Ni plating layer is easily peeled off by applying a light shock after the heat oxidation treatment, If it is rapidly cooled with water or cold air after the treatment, internal stress is generated in the copper oxide part due to the difference in thermal expansion coefficient, and N
It is preferable because the i-plated layer can be peeled off more easily.

In the above description, the removal of the Ni plating was mainly described, but the same applies to the case of Ag-based plating, and the oxygen that has diffused and migrated toward the copper alloy base material through the Ag plating layer by thermal oxidation is used. A brittle copper oxide is formed at the interface, and the Ag-based plating layer can be easily removed.
There is also no particular limitation on the type of copper or copper alloy as the base material, as long as it contains copper for forming copper oxide at the interface with the plating layer by heat oxidation treatment It can be applied to copper alloys.

The present invention is configured as described above, and the plating layer can be removed easily and efficiently by a dry process which is extremely simple as compared with the molten metal refining process, and the original copper can be obtained with an extremely high yield. Alternatively, it can be recycled as a copper alloy raw material.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples, and any changes or modifications may be made without departing from the spirit of the above and the following. It is included in the technical scope of the present invention.

Example 1 As a raw material, F equivalent to JIS H3100 C1100
0.8 on the surface of e-containing copper alloy (Fe content: 1% by weight)
Recovered product (10mm × 50
(mm × 1.5 mm) 100 kg was used, and as shown in FIG. 4, after charging the rotary resistance heating furnace 1 open to the atmosphere and rotating at 10 rpm for 10 minutes at 800 ° C. Then, this was sent to a vibrating screen 2 equipped with an air cooler to be rapidly cooled and vibrated to remove the Ni plating layer by peeling, and then sent to an induction melting furnace 3 to be heated and melted at 1150 ° C.
The obtained molten metal, a raw material which was not subjected to the above treatment at all, and an oxidative refining of this raw material by a conventional method (after blowing air into the molten metal at 1150 ° C. at a rate of 0.01 l / min · molten metal for 15 minutes, Method of removing floating oxides from the surface of the molten metal by rake) Cu, Fe,
The respective contents of Ni were measured, and the results shown in Table 2 below were obtained.
Table 2 also shows the recovery yield of copper.

[0019]

[Table 2]

As is clear from Table 2, according to the method of the present invention, Ni can be removed as much as possible without removing Fe, and a very high copper yield can be secured. I understand.

In the same manner as above, a recovered copper alloy product having an Fe content of 3% by weight and a Ni-based plating deposition amount of 0.8% by weight was regenerated. It could be regenerated at a copper yield of 95.2% by weight as a copper alloy having almost no Ni content, with almost no decrease.
Also, when the rapid cooling and the peeling removal of the plating layer were carried out by spraying with cold water instead of the air cooling after the heating and oxidation, a high removal rate could be obtained similarly. When the same experiment was conducted by changing the temperature rising rate during the heat oxidation treatment to 5 ° C./min and 50 ° C./min, almost no difference was observed in the Ni removal rate.

Further, when a Cu-1% Fe alloy recovered product having an Ag coating amount of 0.8% by weight was subjected to the same plating removal treatment as above, almost the same result as the Ni plating removal treatment was obtained. It was

[0023]

The present invention is configured as described above, and can easily and efficiently remove the Ni-based or Ag-based plating layer on the surface of copper or copper alloy by a dry treatment which is extremely simple as compared with the molten metal refining treatment. In addition, it can be regenerated as the original copper or copper alloy raw material with an extremely high yield.

[Brief description of drawings]

FIG. 1 is a graph of thermal analysis results showing an increase in weight of a Ni-plated copper alloy during a thermal oxidation treatment.

FIG. 2 is a graph showing a relationship between a heat oxidation treatment temperature and a treatment time and a residual Ni concentration after dissolution.

FIG. 3 is likewise a graph showing the relationship between the temperature and the treatment time of the heat oxidation treatment and the residual Ni concentration after dissolution.

FIG. 4 is a conceptual explanatory diagram showing a reproduction processing process using the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takayoshi Ikeda 14-1 Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Kobe Steel Works, Ltd. Chofu Works (72) Inventor Eiji Yoshida 14-1 Chofu Minatomachi, Shimonoseki City, Yamaguchi Company Kobe Steel Works Chofu Factory (72) Inventor Hirofumi Okada 14-1 Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Kobe Steel Works Chofu Factory (72) Inventor Kiyomasa Oga 1-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture No. 5 Inside Kobe Research Institute of Kobe Steel, Ltd. (72) Inventor Motohiro Arai 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Inside Kobe Research Institute of Kobe Steel, Ltd.

Claims (3)

[Claims] 1. A copper or copper-based alloy having a Ni-based or Ag-based plated layer formed on its surface is heated in an oxidizing atmosphere to form a boundary between the copper or copper-based alloy and the Ni-based or Ag-based plated layer. Ni after forming a brittle layer of copper oxide
A method for stripping a copper or copper alloy surface by stripping and removing the base or Ag-based plating layer. 2. The plating stripping method according to claim 1, wherein heating is performed at 700 to 1000 ° C. for 3 to 20 minutes. 3. The plating stripping method according to claim 1, wherein the Ni-based or Ag-based plating layer is stripped and removed after cooling after heating or after cooling.