JP2023031170A - Method for separating tin-nickel from tin-nickel-containing mixture - Google Patents

Abstract

To provide a method for separating tin-nickel from a tin-nickel-containing mixture having increased separation handiness.SOLUTION: A method for separating tin-nickel from a tin-nickel-containing mixture comprises the steps of: (a) dissolving the mixture with acid to prepare an acidic solution; (b) electro-crystallizing the acidic solution in an electrocrystallization tank to form a tin precipitate on the surface of a cathode; and (c) taking out the tin precipitate from the electrocrystallization tank. According to this invention, high-purity tin can be easily taken out from the tin-nickel-containing mixture.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for separating tin and nickel from a mixture containing tin and nickel, and more particularly to a method for separating tin and nickel from a mixture containing tin and nickel, which enables separation of tin with high purity. .

A barrel plating method is known as a method for imparting conductivity to the surface of an object to be plated, such as an electronic component. In the barrel plating method, small iron balls pre-plated with tin, etc. called plating media or dummy media are put into the barrel together with the object to be plated, and the object to be plated is agitated while being energized. (For example, Patent Document 1).

Plating media are used repeatedly in this method. Due to this repeated use, the plating media continues to grow with the plating metal (ie, a mixture of tin and nickel) layered on its surface each time it is used. When the outer diameter and specific gravity finally deviate from the optimized conditions of the method, the plating media become used and need to be replaced with new media.

On the other hand, plated metals are scarce and expensive. Therefore, there is an increasing demand for separating and recovering tin and nickel by stripping the plating metal from the used plating media. For example, in Patent Document 2, after dissolving the plating metal from the used plating media with an acid, tin and nickel are separated by selectively adsorbing tin ions from the resulting acid solution through an ion exchange resin. discloses how to do so.

However, the use of such an ion-exchange resin cannot be said to have a sufficient adsorption efficiency of tin ions from the acid solution, and it cannot be said that it is easy to use industrially. In addition, desorption of tin ions from the adsorbed ion-exchange resin requires complicated work. Moreover, the tin component that can be recovered by this is in the form of hydroxide (Sn(OH) ₂ ), and the purity of tin is at most about 60% by mass, so the recovery efficiency is considered to be low. I have to say.

JP-A-61-015999 JP 2019-026928 A

An object of the present invention is to solve the above problems, and an object of the present invention is to provide a method for separating tin and nickel from a mixture containing tin and nickel in which the simplicity of separation is enhanced. That's what it is.

The present invention is a method for separating tin and nickel from a mixture containing tin and nickel, comprising:
(a) dissolving the mixture with an acid to prepare an acidic solution;
(b) electrodepositing the acidic solution in an electrodeposition tank to form a tin deposit on the surface of the cathode; and (c) removing the tin deposit from the electrodeposition tank;
A method comprising:

In one embodiment, the acid is hydrochloric acid.

In a further embodiment, the acidic solution is prepared by dissolving the mixture in the hydrochloric acid having a concentration of 1 mol/L to 5 mol/L at a temperature of 85°C to 98°C.

In one embodiment, an insoluble electrode is arranged as an anode in the electrodeposition tank.

In one embodiment, the insoluble electrode is an iridium dioxide electrode.

In one embodiment, the mixture is powder obtained from used plating media.

According to the present invention, highly pure tin can be separated from a mixture containing tin and nickel without requiring complicated operations. On the other hand, after separating the tin, a nickel-rich residual solution can be obtained. The tin deposits obtained according to the present invention can be purified, if desired, recovered as ingots of metallic tin, and applied for further uses. Nickel contained in the residual solution can also be recovered, for example, by electrodeposition and purification, as ingots of metallic nickel.

BRIEF DESCRIPTION OF THE DRAWINGS It is a flow diagram explaining an example of the separation method of tin and nickel of this invention. (a) is a photograph showing needle-like deposits formed on the cathode by electrodeposition of the sample solution (acidic solution) of Example 6, and (b) is a photograph showing electrodeposition of the sample solution (acidic solution) of Example 7. 1 is a photograph showing deposits in the form of agglomeration of small clumps formed on the cathode by .

The present invention will be described in detail below.

FIG. 1 is a flow diagram illustrating an example of the method for separating tin and nickel according to the present invention.

In the separation method of the present invention, a given mixture is first dissolved with acid (reference numeral 12 in FIG. 1).

The mixture is a solid, liquid, or combination of materials containing tin and nickel. Examples of such a mixture include, for example, powder that constitutes the surface layer (metal layer) of the plating media used by barrel plating and is removed from the iron balls of the core of the plating media. The powder recovered from the plating media thus obtained contains tin and nickel.

The mixture of tin and nickel may be other mixtures obtained from sources other than the plating media described above.

Such other mixtures include, for example, waste liquids of tin-nickel alloy plating; sludge generated during tin-nickel alloy plating; mixtures of waste liquids obtained in each of tin plating and nickel plating; Constituent components of tin plating, nickel plating, and these alloy platings attached to jigs used and power supply terminals used in barrel plating; and combinations thereof. Other mixtures may be used in combination with the mixture obtained from the plating media described above.

The content of tin and nickel in this mixture is not particularly limited. % by mass or more and nickel is 90% by mass or less. If the tin content in the mixture is less than 5% by mass, the tin content in the mixture as a whole may be too low to form a sufficient tin precipitate, which will be described later. When the tin content is as low as this, the electrolytic potential applied during the electrodeposition described later is further lowered, and the electrodeposition is performed in multiple stages (for example, two to three stages). It is possible to encourage the formation of tin deposits.

The mixture of tin and nickel contains other metals (for example, iron (Fe) derived from iron balls forming the core of the plating media, and impurities such as copper (Cu), zinc (Zn), chromium (Cr), cobalt (Co), boron (B), silicon (Si), etc.) and/or other impurities may be included. The concentration of impurities contained in the mixture is not particularly limited, but is kept below 1% by weight relative to the total weight of the mixture in order to prevent the separation of tin and nickel from being disturbed for unforeseen reasons. preferably.

The mixture of tin and nickel may be one in which water is added in addition to the above tin, nickel and impurities. Examples of water include pure water, ion-exchanged water, distilled water, RO water, and tap water, and combinations thereof.

For example, when this mixture is obtained from used plating media, the used plating media is once baked under predetermined conditions, and the metal layer components forming the core material iron balls and the surface layer is separated from The water added at that time forms a slurry together with the metal layer components forming the surface layer, and this can be used as the mixture.

The acid is added, for example, to promote sufficient dissolution of the tin and nickel contained in the mixture to form tin (Sn) ions and nickel (Ni) ions in the resulting acidic solution.

Although the type of acid used in the present invention is not particularly limited, it is, for example, an inorganic acid. Examples of inorganic acids that can be used in the present invention include hydrochloric acid, sulfuric acid, nitric acid, hydrogen peroxide, and phosphoric acid, and combinations thereof. For example, when the separated and recovered tin or nickel is reused to prepare a new plating solution, it is preferable to use hydrochloric acid or sulfuric acid as the acid. In particular, hydrochloric acid is more preferable because it can form tin(II) chloride or nickel(II) chloride, which has relatively excellent solubility, and is convenient for reuse in the plating solution.

When hydrochloric acid is used as the acid, the concentration of hydrochloric acid added is preferably 1 mol/L to 5 mol/L, more preferably 2 mol/L to 4 mol/L. If the concentration of hydrochloric acid is less than 1 mol/L, the formation of tin (Sn) ions and nickel (Ni) ions from the mixture will be insufficient, resulting in tin deposition in the subsequent electrodeposition step (reference numeral 14 in FIG. 1). Things can be difficult to form efficiently. If the concentration of hydrochloric acid exceeds 5 mol/L, white smoke of hydrogen chloride may be generated in a series of operations in the present invention, and there is a risk of harming the health of workers due to deterioration of the working environment. Additional equipment may be required to prevent this, and there may be problems such as the possibility of promoting corrosion of the equipment used. Alternatively, concentrated hydrochloric acid may be used as the acid to shorten the dissolution time of the mixture. If concentrated hydrochloric acid is used, it is preferable to have sufficient hydrogen chloride purification equipment installed to keep workers safe.

In order to increase the dissolution efficiency of tin and nickel in the mixture, it is preferable that the acid is added at a predetermined temperature. Such temperatures are preferably between 85°C and 98°C, more preferably between 94°C and 98°C. If acid addition to the mixture is performed, agitation may be performed as necessary using means well known to those skilled in the art. A propeller type stirrer can be used for stirring, and the material constituting the stirring tank is, for example, tantalum or zirconium.

Thus, an acidic solution is prepared by dissolving the above mixture with an acid.

The pH of the prepared acidic solution is not necessarily limited, but is preferably 0-4, more preferably 0.1-3. If the pH of the acidic solution exceeds 4, it may become difficult to efficiently perform the electrodeposition step described below.

Then, an acidic solution is electrodeposited in an electrodeposition tank (reference numeral 14 in FIG. 1).

The electrodeposition tank is used for normal electrodeposition, electrodeposition, etc., and the capacity is not particularly limited. The acid solution prepared above is placed in this electrodeposition tank, and electrodeposition is performed. The number of electrodeposition tanks is not particularly limited, and can be appropriately selected according to the amount of the acid solution to be used.

Cathodes (working electrodes) used for electrodeposition include stainless steel (eg, sus304) and iron. Stainless steel is preferred because it has some resistance to the acids mentioned above. The surface of the cathode may be surface-treated by means and methods known to those skilled in the art, if necessary. Other conditions such as the size of the cathode can be appropriately selected by those skilled in the art. In order to promote deposition of tin by electrodeposition, such a cathode is preferably tin-plated in advance using a method known to those skilled in the art.

As the anode (reference electrode) used for electrodeposition, an electrode made of platinum or a platinum-based material can be used. For example, an insoluble electrode is preferably used to prevent corrosion during electrodeposition. The insoluble electrode is, for example, an electrode obtained by thermally decomposing platinum or iridium into a tantalum or titanium-based material, which is a corrosion-resistant material. Insoluble electrodes are electrodes that can be used in a variety of conditions and applications, such as chlorine evolution conditions, high current densities, and the like. In the present invention, it is preferred to use an iridium dioxide electrode because the corrosion of the electrode is significantly improved in the acid solution of relatively high concentration. The iridium dioxide electrode is, for example, an insoluble electrode obtained by coating a film containing iridium on titanium, which is a corrosion-resistant material known in the art, by a method known to those skilled in the art. Other conditions such as the size of the anode can be appropriately selected by those skilled in the art.

For such an electrodeposition vessel, electrodeposition takes place at relatively low current densities. The current density that can be employed for electrodeposition of acidic solutions is preferably 1 A/dm ² to 5 A/dm ² , more preferably 2 A/dm ² to 4 A/dm ² . If the current density is less than 1 A/dm ² , it may take a longer time to deposit tin on the cathode, or the efficiency of deposition may decrease, resulting in poor productivity. If the current density exceeds 5 A/dm ² , the content of nickel contained as an impurity in the tin deposits formed on the cathode may increase. In the present invention, there is a tendency that the lower the current density employed, the higher the rate at which tin is preferentially electrodeposited over nickel. In order to promote preferential electrodeposition of tin, the current density is preferably set low within the above range.

The time required for electrodeposition is not necessarily limited because it depends on the size of the electrodeposition tank used, the concentrations of tin (Sn) ions and nickel (Ni) ions in the acidic solution, and the types and concentrations of impurities. Any time can be set by the trader. The temperature applied for electrodeposition is also not particularly limited, but in order to efficiently form a tin deposit on the cathode, the temperature is adjusted to, for example, 20°C to 30°C, preferably 25°C to 30°C. preferably. The temperature in the electrodeposition tank tends to rise due to the heat of electrolysis. The temperature of the electrodeposition tank is preferably adjusted to 50° C. or lower in order to favorably form a tin deposit on the cathode.

Both tin and nickel contained in an acidic solution are generally classified as base metals. It was found that precipitation was possible in Therefore, in the present invention, tin is preferentially deposited on the cathode side by this electrodeposition step, and nickel is left as a residue in the aqueous solution, thereby separating tin and nickel contained in the acidic solution. be able to.

This allows the electrodeposition of the acidic solution to form a tin deposit on the surface of the cathode.

The tin deposit is then removed from the electrodeposition tank (16 in FIG. 1).

Specifically, the tin deposit can be separated from the residual solution containing nickel (Ni) ions, for example, by taking out the cathode together with the tin deposit formed from the electrodeposition tank. The removed tin deposit is separated into cathode and tin deposit (18 in FIG. 1) using means and/or methods well known to those skilled in the art. Water washing may be performed using means known to those skilled in the art.

In this way, metallic tin, constituted as tin deposits, is recovered (reference numeral 20 in FIG. 1) and tin and nickel can be separated from the mixture containing tin and nickel.

The recovered metallic tin (tin deposit) preferably contains tin with a purity of at least 70% or greater, more preferably 80% or greater, and even more preferably 90% or greater. This far exceeds the purity of metallic tin (approximately 65%) that can be recovered from spent plating media without refining. In addition, since the electrodeposition process is employed as described above, tin and nickel can be easily separated without complicated work.

Due to its high purity, the metallic tin thus obtained can shorten the time required for refining, and can be reused, for example, for the preparation of a plating solution used in the production of new plating media.

On the other hand, tin (Sn) ions are scarcely present in the residual solution after the tin deposits are removed as described above, and nickel (Ni) ions far exceeding them remain.

Therefore, in the present invention, nickel deposits can be formed on the surface of the cathode by further electrodepositing the residual solution (reference numeral 22 in FIG. 1).

The electrodeposition bath, anode and cathode used for electrodeposition of the residual solution are similar to those used for the formation of the tin deposit (14 in FIG. 1). The cathode taken out for taking out the tin deposit was set to a new one, and the electrodeposition tank and the anode used in the formation of the tin deposit (reference numeral 14 in FIG. 1) were used as they were. may

The current density and temperature used for electrodeposition of this residual solution can be selected by those skilled in the art as suitable conditions for nickel deposition. Since almost no tin (Sn) ions are already present in the residual solution, nickel (Ni) ions are attracted to the cathode by this electrodeposition, and nickel deposits are formed on the surface of the cathode. .

After that, the nickel deposit is taken out from the electrodeposition tank, for example, by taking out the cathode with the nickel deposit formed thereon from the electrodeposition tank (reference numeral 24 in FIG. 1). The removed nickel deposit is separated into cathode and nickel deposit (26 in FIG. 1) using means or methods well known to those skilled in the art. Water washing may be performed using means known to those skilled in the art. Metallic nickel (nickel deposits) thus recovered contains, for example, nickel with high purity.

Alternatively, in the present invention, the tin deposit (reference numeral 16 in FIG. 1) taken out from the electrodeposition tank may be re-dissolved in acid in order to further increase the purity of tin. (Reference numeral 28 in FIG. 1). Various conditions such as the type and concentration of the acid used for this re-dissolution are the same as those of the acid solution preparation process described with the reference numeral 12 in FIG.

Then, the redissolved solution is subjected to further electrodeposition, for example, in another electrodeposition tank in the same manner as described above. The electrodeposition bath, anode and cathode used for further electrodeposition, and the electrodeposition conditions (e.g., current density, temperature, time) are the same as those in the acidic solution electrodeposition step described with reference numeral 14 in FIG. may be selected. Finally, this further electrodeposition is carried out by changing the current density at the appropriate time. The voltage of the DC power supply employed for this further electrodeposition is preferably set to an automatic constant voltage for automatic control.

After that, for example, by taking out the cathode formed with the tin deposit from the electrodeposition tank, the tin deposit with a higher purity of tin can be taken out from the electrodeposition tank. The resulting tin deposit may be washed with water and dried using means known to those skilled in the art.

In this way, metallic tin, constituted as tin deposits, is recovered (reference numeral 20 in FIG. 1). The recovered metallic tin (tin deposit) preferably contains tin in a purity of at least 95% or greater, more preferably 98% or greater, and even more preferably 99.9% or greater. Thus, in the present invention, metallic tin can be directly recovered simply and with high purity. The obtained metallic tin can be reused, for example, for the preparation of a tin plating solution used in the production of new plating media and/or as a tin electrode plate in tin plating, without further refining. can.

The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these.

(Example 1: Recovery of tin metal from tin/nickel mixed undiluted solution)
10 g of the residual powder (tin-nickel mixture) obtained by removing the iron ball of the core of the used plating media was dissolved in 5 L of 3 mol/L hydrochloric acid and stirred at 92±2° C. for 6 hours. An acidic solution was prepared. The pH of the resulting acidic solution was 0.24. Furthermore, the content of metal components contained in this acidic solution was analyzed with a high frequency inductively coupled plasma (ICP) emission spectroscopy/mass spectrometer (ICP-7510 manufactured by Shimadzu Corporation). Table 1 shows the results.

Next, the resulting acidic solution was charged into an electrodeposition tank (5 L), the anode (iridium dioxide electrode) and the cathode (stainless steel electrode) were inserted into the acidic solution, and the current density was 4 A/dm ² at 50 ° C. Electrodeposited for 1 hour. The area ratio of anode to cathode was 2:1. It was visually confirmed that a deposit was formed on the cathode through this electrodeposition.

On the other hand, the remaining solution after removing the cathode had a green color indicating that nickel remained. This residual solution was analyzed by the ICP emission spectroscopy/mass spectrometer in the same manner as described above. Table 1 shows the results.

(Example 2: Recovery of tin metal from tin/nickel mixed undiluted solution)
Electrodeposition was carried out in the same manner as in Example 1 except that the current density and temperature were not changed and the electrodeposition time of the acidic solution was changed to 3 hours, and the precipitate formed on the cathode was taken out. The residual green solution after removing the cathode was analyzed in the same manner as in Example 1 by an ICP emission spectroscopy/mass spectrometer. Table 1 shows the results.

(Example 3: Recovery of tin metal from tin/nickel mixed undiluted solution)
Electrodeposition was carried out in the same manner as in Example 1 except that the current density and temperature were not changed, and the electrodeposition time of the acidic solution was changed to 6 hours, and the precipitate formed on the cathode was taken out. The residual green solution after removing the cathode was analyzed in the same manner as in Example 1 by an ICP emission spectroscopy/mass spectrometer. Table 1 shows the results.

As shown in Table 1, through the electrodeposition performed in Examples 1 to 3, the concentration of tin (Sn) contained in the residual solution was lower than that of the undiluted solution before electrodeposition, and the electrodeposition time was longer. Indeed, it can be seen that the concentration of tin is lowered.

(Example 4: Recovery of tin metal from tin/nickel mixed undiluted solution)
20 g of the residual powder (tin-nickel mixture; obtained separately from Example 1) obtained by removing the iron balls of the core of the used plating media was dissolved in 5 L of 3 mol/L hydrochloric acid. An acidic solution was prepared by stirring at ±2° C. for 6 hours. The resulting acidic solution had a pH of 4.0. Furthermore, the content of metal components contained in this acidic solution was analyzed with a high frequency inductively coupled plasma (ICP) emission spectroscopy/mass spectrometer (ICP-7510 manufactured by Shimadzu Corporation). Table 2 shows the results.

Next, the resulting acidic solution was charged into an electrodeposition tank (5 L), the anode (iridium dioxide electrode) and the cathode (stainless steel electrode) were inserted into the acidic solution, and the current density was 4 A/dm ² at 50 ° C. Electrodeposited for 7 hours. It was visually confirmed that a deposit was formed on the cathode through this electrodeposition. After that, the deposit formed on the cathode was taken out together with the cathode. It was confirmed that the precipitate obtained had a fine needle-like morphology.

On the other hand, the remaining solution after removing the cathode had a green color indicating that nickel remained. This residual solution was analyzed by the ICP emission spectroscopy/mass spectrometer in the same manner as described above. Table 2 shows the results.

As shown in Table 2, in the electrodeposition performed in Example 4, the concentration of tin (Sn) contained in the residual solution was significantly lower than that of the stock solution before electrodeposition. On the other hand, the concentration of nickel contained in the residual solution did not change significantly before and after the electrodeposition, indicating that almost no nickel moved to the cathode as a deposit.

(Example 5: Recovery of tin metal from tin/nickel mixed undiluted solution)
100 g of the residual powder (tin-nickel mixture; obtained separately from Example 1) obtained by removing the core iron ball of the used plating media was dissolved in 5 L of 3 mol/L hydrochloric acid, and 92 An acidic solution was prepared by stirring at ±2° C. for 6 hours. The resulting acidic solution had a pH of approximately 0.0. Furthermore, the content of metal components contained in this acidic solution was analyzed with a high frequency inductively coupled plasma (ICP) emission spectroscopy/mass spectrometer (ICP-7510 manufactured by Shimadzu Corporation). Table 3 shows the results.

Next, the resulting acidic solution was charged into an electrodeposition tank (5 L), the anode (iridium dioxide electrode) and the cathode (stainless steel electrode) were inserted into the acidic solution, and the current density was 2 A/dm ² at 50 ° C. Electrodeposited for 7 hours. The area ratio of anode to cathode was 2:1. It was visually confirmed that a deposit was formed on the cathode through this electrodeposition. After that, the deposit formed on the cathode was taken out together with the cathode. It was confirmed that the precipitate obtained had a fine needle-like morphology.

On the other hand, the remaining solution after removing the cathode had a dark green color indicating that nickel remained. This residual solution was analyzed by the ICP emission spectroscopy/mass spectrometer in the same manner as described above. Table 3 shows the results.

As shown in Table 3, in ^the electrodeposition performed in Example 5, the residual ^solution was The concentration of tin (Sn) contained in the sample was remarkably lower than that of the undiluted solution before electrodeposition. On the other hand, the concentration of nickel contained in the residual solution did not change significantly before and after the electrodeposition, indicating that nickel hardly moved to the cathode as a deposit.

Although the current density (2 A/dm ² ) used in Example 5 is lower than the current density (4 A/dm ² ) used in Example 4, the concentration of tin (Sn) was changed as described above. One of the reasons for the significant decrease is that the concentration of tin in the stock solution used in Example 5 (6020 mg/L) was lower than the concentration of tin in the stock solution used in Example 4 (3450 mg/L). It is possible that it was higher than the

(Example 6: Recovery of tin metal from tin/nickel mixed undiluted solution (1))
600 g of the residual powder (tin-nickel mixture) obtained by removing the core iron ball of the used plating media was dissolved in 5 L of 3 mol/L hydrochloric acid and stirred at 92±2° C. for 6 hours. 5 L of acid solution was prepared. The pH of the resulting acidic solution was 0.24. This operation was repeated 10 times, and the obtained materials were combined to prepare 50 L of an acidic solution (pH 0.24).

A sample solution of pH 3.0 was prepared by taking 25 L of this acidic solution and adding a 10% by mass sodium hydroxide aqueous solution.

The content of metal components contained in this sample solution was analyzed by a high frequency inductively coupled plasma (ICP) emission spectroscopy/mass spectrometer (ICP-7510 manufactured by Shimadzu Corporation). Table 4 shows the results.

Next, this sample solution was charged into an electrodeposition tank, an anode (iridium dioxide electrode) and a cathode (stainless steel electrode) were inserted into the sample solution, and the liquid temperature was adjusted to 35 ° C. to 45 ° C. while adjusting the liquid temperature to 4 A / dm ² . Electrodeposited at current density for 4 hours. The area ratio of anode to cathode was 2:1. It was visually confirmed that a deposit was formed on the cathode through this electrodeposition. After that, the precipitate formed on the cathode was taken out together with the cathode, and the obtained precipitate was photographed (FIG. 2(a)). It was confirmed that the precipitates obtained as shown in FIG. 2(a) had fine needle-like morphology.

Further, 30 g of the precipitate formed on the cathode is redissolved in 3 mol/L hydrochloric acid, 20 mL of a 20% hydrochloric acid solution is added to 10 mL of the resulting solution, and titration is performed with a normal iodine solution using starch as an indicator. The concentration of tin (Sn) contained in the precipitate was measured. On the other hand, 30 g of the precipitate formed on the cathode was re-dissolved in 3 mol/L hydrochloric acid, 10 mL of a 50% citric acid solution was added to 1 mL of the resulting solution, and aqueous ammonia was added to make it alkaline, followed by 50% potassium iodide. The concentration of nickel (Ni) contained in the precipitate was measured by adding 1 mL and titrating with a standard potassium cyanide solution containing silver nitrate until the white turbidity of silver iodide disappeared. Table 7 shows the results.

(Example 7: Recovery of tin metal from tin/nickel mixed undiluted solution (2))
For the remaining sample solution (25 L) of the 50 L acidic solution (pH 0.24) prepared in Example 6, without adjusting the pH with sodium hydroxide, the content of the metal component contained in this sample solution was It was analyzed by an ICP emission spectroscopy/mass spectrometer in the same manner as in Example 6. Table 5 shows the results.

As shown in Table 5, the sample solution (pH 0.24) used in this example had a different pH, and the content of the metal component contained in the sample solution was adjusted in Example 6. It was confirmed to be the same as the sample solution (pH 3.0).

Then, this sample solution was charged into an electrodeposition tank and electrodeposited in the same manner as in Example 6. It was visually confirmed that a deposit was formed on the cathode through this electrodeposition. After that, the precipitate formed on the cathode was taken out together with the cathode, and the obtained precipitate was photographed (FIG. 2(b)). As shown in FIG. 2(b), it was confirmed that the obtained precipitate had a form of agglomeration of small lumps.

Also, the concentrations of tin (Sn) and nickel (Ni) contained in the deposits formed on the cathode were measured in the same manner as in Example 6. Table 6 shows the results.

As shown in Table 6, the deposit formed on the cathode contained high-purity tin regardless of whether the sample solutions of Examples 6 and 7 were used. In particular, the sample solution of Example 6, which was pH-adjusted with sodium hydroxide, was able to further increase the tin concentration in the precipitate compared to the sample solution of Example 7, which was not adjusted. I understand. On the other hand, even when the pH was not adjusted with sodium hydroxide (Example 7), it was found that about 93% tin-containing precipitates could be easily removed from the sample solution containing tin and nickel.

According to the present invention, tin and nickel can be easily separated from a mixture containing tin and nickel without using an expensive ion exchange resin or the like. The method of the present invention can be used, for example, to separate tin and nickel that make up the surface layer of used plating media, and each can be recovered. After recovery, it can be reused as a constituent material of plating media by performing refining or the like known to those skilled in the art as necessary.

12 Preparation step of acidic solution 14 Electrodeposition step of acidic solution 16 Removal step of tin deposit 18 Separation of cathode and tin deposit 20 Recovery of metallic tin 22 Electrodeposition of residual solution 24 Removal of nickel deposit 26 Removal of metallic nickel Recovery 28 Redissolution of tin deposits in acid

Claims (6)

A method for separating tin and nickel from a mixture containing tin and nickel, comprising:
(a) dissolving the mixture with an acid to prepare an acidic solution;
(b) electrodepositing the acidic solution in an electrodeposition tank to form a tin deposit on the surface of the cathode; and (c) removing the tin deposit from the electrodeposition tank;
A method, including 2. The method of claim 1, wherein said acid is hydrochloric acid. 3. The method according to claim 1 or 2, wherein the acidic solution is prepared by dissolving the mixture in the hydrochloric acid having a concentration of 1 mol/L to 5 mol/L at a temperature of 85°C to 98°C. Method. 4. The method according to any one of claims 1 to 3, wherein an insoluble electrode is arranged as an anode in the electrodeposition tank. 5. The method of claim 4, wherein said insoluble electrode is an iridium dioxide electrode. 6. The method according to any one of claims 1 to 5, wherein the mixture is powder obtained from used plating media.

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