Method for treating object comprising copper and tin

Abstract

To provide a method for efficiently separating copper and tin from an object comprising copper and tin.SOLUTION: A method for treating an object comprising copper and tin, comprises a step of heating the object comprising copper and tin in a molten bath of lead and tin to obtain a melt, and a step of separating copper from the melt. In the step of obtaining the melt, the heating temperature is adjusted to 250°C or higher and 450°C or lower, and the ratio of lead mass to tin mass (Pb / Sn) in the melt is adjusted to 0.5 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for treating an object containing copper and tin. [Background technology]

[0002] Conventionally, methods for recovering tin from tin-containing materials that contain copper and lead together with tin have been known. For example, Patent Document 1 proposes a method in which tin is oxidatively leached from a tin-containing material using sulfuric acid, and the leached solution is neutralized to produce a tin-containing precipitate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-130015 Summary of the Invention [Problem to be solved by the invention]

[0004] Various tin-based products have been known for some time, including tinplate, solder, lead frames, bronze castings, tin-plated bearing alloys and electrical wires, and ITO transparent electrodes. However, tin recycling is virtually nonexistent. Tinplate is recovered as steel sheets without the tin being extracted. Demand for lead-free solder is increasing, but like lead frames used in electronic components and copper alloys, it is recovered as copper alloys without separating the tin. Bronze castings are recycled as castings, but the tin is not separated here either. Tin plating is also recovered as bearing alloys and electrical wires without separating the tin. With the recent increase in waste from LCD panels and solar cells, preventing the diffusion of tin contained in ITO transparent electrodes presents a challenge.

[0005] However, the processing method described in Patent Document 1 involves waste liquid treatment, making the process complicated. On the other hand, when attempting to recycle tin via copper smelting, there is a problem in that tin is relatively noble, so it is preferentially oxidized during oxidation smelting and is likely to enter the slag, making recovery difficult. It is also known that the large difference in melting points between copper and tin can be utilized to separate them by centrifugation, but even in this case, there is also the problem that a certain amount of copper ends up being contained in the molten tin.

[0006] An object of one embodiment of the present invention is to provide a method capable of efficiently separating copper and tin from an object containing copper and tin. [Means for solving the problem]

[0007] A first aspect of the present invention is a step of heating an object containing copper and tin in a molten metal of lead and tin to obtain a solution; and separating the copper from the solution; In the step of obtaining the solution, the heating temperature is set to 250°C or higher and 450°C or lower, and the mass ratio of lead to tin in the solution (Pb / Sn) is adjusted to 0.5 or higher.

[0008] A second aspect of the present invention is In the method for treating an object containing copper and tin according to the first aspect, the step of obtaining the solution involves heating for 1.5 hours to 4 hours.

[0009] A third aspect of the present invention is The method for treating an object containing copper and tin according to the first aspect further comprises a step of obtaining the object from waste electronic substrates.

[0010] A fourth aspect of the present invention is the step of obtaining the target object includes a step of crushing or pulverizing the waste electronic substrates, and a step of sieving the crushed or pulverized waste electronic substrates; In the method for treating an object containing copper and tin according to the third aspect, in the sieving step, the mesh size is set to 1 mm or more and 5 mm or less, and the under-sieve material is treated as the object.

[0011] A fifth aspect of the present invention is The step of obtaining the target object further includes a step of performing gravity separation on the undersize material, In the method for treating an object containing copper and tin according to the fourth aspect, in the step of performing gravity separation, the heavy specific gravity material side is the object.

[0012] A sixth aspect of the present invention is In the method for treating an object containing copper and tin according to any one of the third to fifth aspects, the waste electronic substrates are substantially free of lead.

[0013] A seventh aspect of the present invention is In the step of performing the gravity separation, a wet gravity separation device using a vibrating table is used to perform gravity separation on the undersize material, which is the method for treating an object containing copper and tin according to the fifth aspect. [Effects of the Invention]

[0014] According to one embodiment of the present invention, copper and tin can be efficiently separated from an object containing copper and tin. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a flowchart showing an example of a method for treating an object containing copper and tin according to a first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Details of the embodiment of the present invention] Next, an embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0017] <First embodiment of the present invention> First, a method for treating an object containing copper and tin according to this embodiment will be described. In this embodiment, a case will be described in which an object 200 containing copper and tin is obtained from a waste electronic substrate 100 and the copper and tin contained in the object 200 are separated. FIG. 1 is a flowchart showing an example of a method for treating an object containing copper and tin according to this embodiment. As shown in FIG. 1, the method for obtaining an object containing copper and tin according to this embodiment includes, for example, a pretreatment step S10, a heating step S20, and a separation step S30. The pretreatment step S10 also includes, for example, a heat treatment step S11, a component peeling step S12, a crushing / pulverizing step S13, a sieving step S14, and a gravity separation step S15.

[0018] (Pretreatment step S10) The pre-treatment step S10 is, for example, a step of performing various pre-treatments on the waste electronic substrates 100 to obtain an object 200 containing copper and tin. In the pre-treatment step S10, it is preferable to perform one or more steps arbitrarily selected from a heat treatment step S11, a component peeling step S12, a crushing / pulverizing step S13, and a sieving step S14.

[0019] The heat treatment step S11 is, for example, a step of performing heat treatment on the waste electronic substrates 100 at a predetermined temperature to separate bromine contained in the waste electronic substrates 100 as a gas. The component removal step S12 is, for example, a step of removing electronic components such as integrated circuits (ICs), resistors, and capacitors from the waste electronic substrates 100 and sending the substrate portion containing copper and tin to the next step.

[0020] The crushing / pulverizing step S13 is, for example, a step of crushing or pulverizing the waste electronic substrates 100 using a crusher. The sieving step S14 is, for example, a step of sieving the waste electronic substrates 100 after crushing or pulverizing. In the sieving step S14, it is preferable to use a mesh size of 1 mm or more and 5 mm or less, and leave the under-sieve material as the target material 200 (or send it to the next step). This allows the glass fibers and the like contained in the waste electronic substrates 100 to be separated, and the proportion of copper and tin in the target material 200 to be increased.

[0021] The gravity separation step S15 is, for example, a step of performing gravity separation on the undersize material obtained in the sieving step S14. In the gravity separation step S15, it is preferable to use the heavy specific gravity material as the target material 200. This allows glass fibers and the like contained in the waste electronic substrates 100 to be separated, and the proportions of copper and tin in the target material 200 to be further increased.

[0022] In the gravity separation step S15, gravity separation is preferably performed using, for example, a wet gravity separation device using a vibration table. The inclination angle of the vibration table is preferably 5 to 15°, and 10° is particularly preferred. The flow rate of water on the vibration table is preferably 1 to 8 L / min, and 3 L / min is particularly preferred. This allows for efficient separation of glass fibers and the like contained in the waste electronic substrates 100, and further increases the proportion of copper and tin in the target objects 200.

[0023] (Heating process S20) The heating step S20 is a step in which, for example, the object 200 is heated in a molten metal of lead and tin using a heating furnace or the like to obtain a solution 300 in which at least a portion of the object 200 is melted. When the object 200 is heated, copper may melt in the solution 300, making it difficult to separate the copper and tin. Therefore, the heating step S20 of this embodiment is characterized by controlling the heating temperature to 250°C or higher and 450°C or lower, and adjusting the mass ratio of lead to tin (Pb / Sn) in the solution 300 to 0.5 or higher. If the heating temperature is lower than 250°C, the formation of the solution 300 is difficult to proceed. On the other hand, if the heating temperature exceeds 450°C, copper is more likely to melt into the solution 300. In contrast, by setting the heating temperature within the above range, melting of copper in the solution 300 is suppressed, and copper and tin can be efficiently separated. Furthermore, if the Pb / Sn ratio is less than 0.5, copper will melt into the solution 300. In contrast, by setting the Pb / Sn ratio to 0.5 or more, copper melting in the solution 300 is suppressed, and copper and tin can be separated efficiently. Furthermore, in the heating step S20, heating is preferably performed at a temperature of 350°C or higher and 450°C or lower, and more preferably at a temperature of 380°C or higher and 400°C or lower. The Pb / Sn ratio is preferably adjusted to 0.75 or higher, more preferably 1.0 or higher, even more preferably 4.0 or higher, and particularly preferably 10 or higher. This improves the efficiency of separation of copper and tin. While the upper limit of the Pb / Sn ratio is not particularly limited, taking into account the cost of lead added to the target object 200, the Pb / Sn ratio may be adjusted to, for example, 20 or lower. Here, the solution 300 contains a solid containing copper as well as molten lead and tin.

[0024] In the heating step S20, it is preferable to add lead before heating (i.e., before obtaining the solution 300). This keeps the solution 300 lead-rich from the beginning, suppressing the melting of copper into the solution 300 and enabling more efficient separation of copper and tin. For the same reason, in the heating step S20, as shown in FIG. 1, tin and lead prepared separately from the target object 200 may be heated to obtain a second solution in which the Pb / Sn ratio is adjusted to 0.5 or more, and then the target object 200 may be introduced into the second solution to obtain the solution 300. In this case, the composition of the second solution may be adjusted so that the Pb / Sn ratio of the solution 300 is maintained at 0.5 or more even if the tin contained in the target object 200 melts.

[0025] As described above, the target object 200 in this embodiment is derived from a waste electronic substrate 100. In recent years, due to the use of lead-free solder, waste electronic substrates 100 are almost always substantially free of lead. The inventors discovered that even in such cases, adding lead to the solution 300 and maintaining the tin-to-lead mass ratio in the solution 300 within the above range can suppress melting of copper in the solution 300 and facilitate separation of copper and tin. While separating copper is difficult if copper melts in the solution 300, separating tin and lead from a solution 300 containing tin and lead can be accomplished relatively easily using known methods. Note that "substantially free of lead" in a waste electronic substrate 100 means, for example, that the lead content is 0.1 wt% or less.

[0026] In the heating step S20, heating is preferably performed for 1.5 hours or more and 4 hours or less. If the heating time is less than 1.5 hours, the formation of the solution 300 may be insufficient. If the heating time exceeds 4 hours, the cost may be too high. In contrast, by setting the heating time within the above range, copper and tin can be separated efficiently while keeping costs down.

[0027] In the heating step S20, a composition analysis of the target object 200 may be performed before heating to measure the content of each metal (copper, tin, etc.), which makes it possible to estimate, for example, the amount of lead to be added to make the Pb / Sn ratio 0.5 or more.

[0028] (Separation process S30) The separation step S30 is, for example, a step of separating copper from the solution 300. Since copper is inhibited from dissolving in the solution 300 and exists mostly in a solid state, it can be easily separated by known means. Specifically, for example, since the temperature of the solution 300 is relatively low, the solution 300 and the copper can be separated using a metal pump.

[0029] Since the solution 300 after copper separation contains tin and lead, the tin and lead may be separated by known means, or the solution may be used as a raw material for lead smelting or tin smelting.

[0030] Through the above steps, copper and tin can be efficiently separated from the copper- and tin-containing object 200. Specifically, for example, the copper content in the solution 300 can be set to less than 1 wt %, and copper and tin can be efficiently separated.

[0031] <Other Embodiments of the Present Invention> Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention.

[0032] For example, in the above embodiment, the case where the object 200 is derived from the waste electronic substrates 100 has been described, but the object 200 may contain tin and copper and is not limited to being derived from the waste electronic substrates 100. Specifically, the object 200 may be a selected scrap other than the waste electronic substrates 100, or may be an intermediate product of various smelting processes. [Example]

[0033] Next, examples of the present invention will be described. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

[0034] Example 1 In Example 1, 298.30 g of tin and 298.30 g of lead were placed in a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal (used as a reducing agent) so that the mass ratio of lead to tin (Pb / Sn) in the solution was 1.0. The furnace was then heated to 400°C, melting the tin and lead to form a solution.

[0035] 72.86 g of copper was added to this solution and maintained at 400°C for 2 hours. In other words, in this example, copper was added after forming a solution in which tin and lead were molten, and it was evaluated whether the copper dissolved in the solution. The amount of copper added was such that the mass ratio of tin to copper was approximately 4.1:1. This was based on the assumption that the target material would be obtained when waste electronic substrates were subjected to pretreatment processes (heat treatment process, component removal process, crushing / pulverization process, sieving process, and gravity separation process).

[0036] A portion of the solution was sampled two hours after the copper was added, and the metal was cooled and analyzed for composition by fluorescent X-ray analysis. The copper content was found to be 0.35 wt%.

[0037] Example 2 In Example 2, 328.57 g of tin and 328.57 g of lead were placed in a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal so that the Pb / Sn ratio was 1.0. The furnace was then heated to 250°C, and the tin and lead were melted to form a solution.

[0038] 73.07g of copper was added to this solution and it was kept at 250℃ for 2 hours. Portions of the solution were sampled 30 minutes, 1 hour, and 2 hours after adding the copper, and the metal was cooled and analyzed for composition by X-ray fluorescence analysis. The results showed that the copper content was 0wt% after 30 minutes of heating, 0wt% after 1 hour of heating, and 0wt% after 2 hours of heating.

[0039] Example 3 In Example 3, 84.30 g of tin and 516.90 g of lead were placed in a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal so that the Pb / Sn ratio was 4.0. The furnace was then heated to 400°C, and the tin and lead were melted to form a solution.

[0040] 65.85g of copper was added to this solution and kept at 400℃ for 2 hours. Then, a part of the solution was sampled 2 hours after adding copper, and after cooling, the metal was analyzed for composition by X-ray fluorescence analysis. The copper content was found to be 0wt%.

[0041] Example 4 In Example 4, 97.42 g of a 60:40 lead:tin alloy and 340.44 g of lead were placed in a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal so that the Pb / Sn ratio was 10. The furnace was then heated to 400°C, and the tin and lead were melted to form a solution.

[0042] 40.72g of copper was added to this solution and kept at 400℃ for 2 hours. Then, a part of the solution was sampled 2 hours after adding copper, and after cooling, the metal was analyzed for composition by X-ray fluorescence analysis. The copper content was found to be 0wt%.

[0043] Example 5 In Example 5, 199.61 g of a 60:40 lead:tin alloy and 156.8 g of tin were placed in a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal so that the Pb / Sn ratio was 0.5. The furnace was then heated to 400°C, melting the tin and lead to form a solution.

[0044] 12.11g of copper was added to this solution and kept at 400℃ for 2 hours. Then, a part of the solution was sampled 2 hours after adding copper, and after cooling, the metal was analyzed for composition by X-ray fluorescence analysis. The copper content was found to be 0.81wt%.

[0045] (Comparative Example 1) In Comparative Example 1, 270.15 g of tin and 270.15 g of lead were placed in a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal so that the Pb / Sn ratio was 1.0. The furnace was then heated to 500°C, and the tin and lead were melted to form a solution.

[0046] 71.76g of copper was added to this solution and it was kept at 500℃ for 2 hours. Portions of the solution were sampled 30 minutes, 1 hour, and 2 hours after adding the copper, and the metal was cooled and its composition was analyzed by X-ray fluorescence analysis. The results showed that the copper content after 30 minutes of heating was 4.17wt%, after 1 hour of heating, it was 3.48wt%, and after 2 hours of heating, it was 5.50wt%.

[0047] (Comparative Example 2) In Comparative Example 2, no lead was added, and 596.60 g of tin was added to a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal (i.e., Pb / Sn was 0).Then, the furnace was heated to 400°C, and the tin was melted to form a solution.

[0048] 72.86g of copper was added to this solution and it was kept at 400℃ for 2 hours. Portions of the solution were sampled 30 minutes, 1 hour, and 2 hours after adding the copper, and the metal was cooled and its composition was analyzed by X-ray fluorescence analysis. The results showed that the copper content after 30 minutes of heating was 3.05wt%, after 1 hour of heating it was 2.17wt%, and after 2 hours of heating it was 5.32wt%.

[0049] (Comparative Example 3) In Comparative Example 3, no lead was added, and 657.14 g of tin was added to a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal (i.e., Pb / Sn was 0).Then, the furnace was heated to 250°C, and the tin was melted to form a solution.

[0050] 73.07g of copper was added to this solution and it was kept at 250℃ for 2 hours. Portions of the solution were sampled 30 minutes, 1 hour, and 2 hours after adding the copper, and the metal was cooled and analyzed for composition by X-ray fluorescence analysis. The results showed that the copper content after 30 minutes of heating was 0.345wt%, after 1 hour of heating it was 1.28wt%, and after 2 hours of heating it was 1.58wt%.

[0051] Comparative Example 4 In Comparative Example 4, no lead was added, and 540.30 g of tin was added to a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal (i.e., Pb / Sn was 0).Then, the furnace was heated to 500°C, and the tin was melted to form a solution.

[0052] 71.76g of copper was added to this solution and it was kept at 500℃ for 2 hours. Portions of the solution were sampled 30 minutes, 1 hour, and 2 hours after adding the copper, and the metal was cooled and analyzed for composition by X-ray fluorescence analysis. The results showed that the copper content after 30 minutes of heating was 5.87wt%, after 1 hour of heating, it was 5.72wt%, and after 2 hours of heating, it was 7.05wt%.

[0053] (Comparative Example 5) In Comparative Example 5, 431.94 g of tin and 168.79 g of lead were placed in a graphite crucible in an electric furnace together with an appropriate amount of binchotan charcoal so that the Pb / Sn ratio was 0.25. The furnace was then heated to 400°C, and the tin and lead were melted to form a solution.

[0054] 66.7g of copper was added to this solution and kept at 400℃ for 2 hours. Two hours after adding the copper, a portion of the solution was sampled and cooled, after which the metal was analyzed for composition by X-ray fluorescence analysis. The copper content was found to be 1.74wt%.

[0055] Table 1 shows the copper content in the solution for Examples 1 to 5 and Comparative Examples 1 to 5.

[0056] [Table 1]

[0057] As shown in Table 1, in Examples 1 to 5, in which the heating temperature was 250°C or higher and 450°C or lower and the Pb / Sn ratio was 0.5 or higher, the copper content in the solution was low. Specifically, the copper content was less than 1 wt% after 2 hours of heating. On the other hand, in Comparative Examples 1 to 5, in which the heating temperature or Pb / Sn value did not satisfy the above conditions, the copper content in the solution was high. Specifically, the copper content was 1 wt% or higher after 2 hours of heating.

[0058] From the above, it was confirmed that by heating an object containing copper and tin in molten lead and tin and appropriately controlling the heating temperature and Pb / Sn ratio, it is possible to suppress the melting of copper into the solution and efficiently separate the copper and tin.

[0059] (Example of starting from discarded electronic circuit boards) Next, an example will be described in which a target containing copper and tin was obtained from a waste electronic substrate, and the copper and tin were separated.

[0060] First, the waste electronic substrates were subjected to a heat treatment process, a component peeling process, a crushing and pulverizing process, and a sieving process to prepare 22.6 g of crushed waste electronic substrates under the sieve. The mesh size of the sieve was set to 2.00 mm.

[0061] Then, under-sieve specific gravity separation was performed using a wet specific gravity separator with a vibrating table (Wilfray table), yielding 9.1 g of heavy specific gravity material and 13.5 g of light specific gravity material. The inclination angle of the vibrating table was 10°, the water flow rate was 3 L / min, and the vibration frequency was 300 rpm.

[0062] Table 2 shows the mass and distribution ratio of Cu, Sn, and Si in the obtained heavy specific gravity material and light specific gravity material.

[0063] [Table 2]

[0064] As shown in Table 2, the heavy specific gravity side had a high proportion of Cu and Sn and a low proportion of Si. From the above, it was confirmed that the proportion of copper and tin in the target material can be increased by performing a pretreatment process.

[0065] A portion of the heavy material, 55 g of tin, and 495 g of lead were placed in a graphite crucible in an electric furnace along with an appropriate amount of binchotan charcoal. The heavy material contained 2.24 g of copper, 0.54 g of tin, and 0.15 g of silicon. The Pb / Sn mass ratio of the contents placed in the graphite crucible was 8.9. The electric furnace was then heated to 400°C and held at 400°C for two hours. After two hours, the lower layer of the solution was collected, and the cooled metal was obtained. The cooled metal contained 347 g of lead and 56 g of tin, with no copper or silicon. From the above, it was confirmed that copper and tin could be separated from waste electronic circuit boards and the tin could be recovered. [Explanation of symbols]

[0066] 100 Waste electronic circuit boards 200 objects 300 Solution S10 Pretreatment process S11 Heat treatment process S12 Parts peeling process S13 Crushing and grinding process S14 Sieving process S15 Gravity sorting process S20 heating process S30 Separation process

Claims

1. a step of heating an object containing copper and tin in a molten metal of lead and tin to obtain a solution; and separating the copper from the solution; A method for treating an object containing copper and tin, wherein in the step of obtaining the solution, the heating temperature is set to 250°C or higher and 450°C or lower, and the mass ratio of lead to tin (Pb / Sn) in the solution is adjusted to 0.5 or higher.

2. 2. The method for treating an object containing copper and tin according to claim 1, wherein the step of obtaining the solution involves heating for 1.5 hours to 4 hours.

3. The method for treating an object containing copper and tin according to claim 1 , further comprising the step of obtaining the object from a waste electronic substrate.

4. the step of obtaining the target object includes a step of crushing or pulverizing the waste electronic substrates, and a step of sieving the crushed or pulverized waste electronic substrates; 4. The method for treating an object containing copper and tin according to claim 3, wherein in the sieving step, the mesh size is set to 1 mm or more and 5 mm or less, and the under-sieve material is treated as the object.

5. The step of obtaining the target object further includes a step of performing gravity separation on the undersize material, 5. The method for treating an object containing copper and tin according to claim 4, wherein in the step of performing gravity separation, the heavy specific gravity material is the object.

6. The method for treating an object containing copper and tin according to claim 3 , wherein the waste electronic substrates are substantially free of lead.

7. 6. The method for treating an object containing copper and tin according to claim 5, wherein in the step of performing gravity separation, gravity separation is performed on the undersize material using a wet gravity separator using a vibrating table.

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