JP5160163B2 - Tin recovery method - Google Patents

Description

  The present invention relates to a method for recovering tin, and more particularly to a method for recovering tin from a tin-containing material containing lead in addition to tin.

  Conventionally, as a method of recovering tin from a tin-containing material containing lead in addition to tin, an alloy containing tin and lead is melted at a temperature of about 300 to 500 ° C., caustic soda is added to the melt, and the melt There is a method in which tin is extracted into sodium stannate as sodium stannate and separated from lead, and then the caustic soda extracted from tin is dissolved in water to form an alkaline solution containing sodium stannate, and tin is recovered by electrolysis or the like. Are known.

Further, as a method for separating and recovering tin in lead in lead refining, lead containing tin is melted, and this melt is reacted with a soda compound, so that tin in the melt is converted to sodium stannate. A method has also been proposed in which soot containing by-product lead stannate is separated from molten lead, sulfur is added to the lead refined soot and leached with water, and then tin is precipitated as calcium stannate with Ca ²⁺ . (For example, refer to Patent Document 1).

  Also, raw material tin such as an alloy containing metal tin or tin is put into an alkali hydroxide aqueous solution of any one of potassium hydroxide, sodium hydroxide and lithium hydroxide, and the aqueous tin hydroxide aqueous solution is stirred or circulated. The reaction is carried out while dripping hydrogen peroxide as a reaction accelerator in the reaction solution while maintaining a predetermined reaction temperature while constantly flowing on the surface to obtain a stannate aqueous solution containing an insoluble matter. There is a method in which the dissolved matter is filtered off and a crystal of an alkali stannate compound of any one of potassium stannate, sodium stannate and lithium stannate is obtained by concentration under reduced pressure, evaporation, crystallization or centrifugation from an aqueous stannate solution. It has been proposed (see, for example, Patent Document 2).

  Furthermore, as a method of recovering metallic tin from solder containing tin as a main component, an acid is added to the tin-containing material to obtain an acid solution in which the tin-containing material is dissolved, and then an alkali agent is added to the acid solution. There has been proposed a method in which tin is obtained by adjusting the pH to 12 or more to obtain an alkaline solution in which tin in a tin-containing material is dissolved, and electrolyzing the alkaline solution (see, for example, Patent Document 3).

Japanese Examined Patent Publication No. 63-19576 (first page) JP 2000-226214 A (paragraph number 0008) JP 2004-315865 A (paragraph numbers 0007-0008)

  However, in the conventional method of adding caustic soda to the above-described alloy melt containing tin and lead, caustic soda is used in an amount about 10 times as much as the amount of tin. . In addition, it is possible to boil the caustic soda solution obtained by dissolving tin extracted caustic soda with water at 350 ° C or higher, completely evaporate the water, and reuse the caustic soda. The energy cost becomes large because it has to be made. Similarly, in the case of the method of Patent Document 1, the amount of soda compound used is very large, and the energy cost becomes large when trying to reuse the soda compound.

  Further, the method of Patent Document 2 is a method for obtaining an alkali stannate compound and not a method for recovering tin. However, even if tin is recovered using an aqueous stannate solution obtained by this method, tin is recovered. It takes a long time to obtain an aqueous acid salt solution. Furthermore, in the method of Patent Document 2, it is necessary to use hydrogen peroxide water, and in the method of Patent Document 3, it is necessary to add an alkaline agent to an acid solution obtained by adding an acid to a tin-containing material. Therefore, a method that can further reduce the chemical cost is desired.

  Therefore, in view of such a conventional problem, the present invention provides a method for recovering tin that can recover tin inexpensively and efficiently from a tin-containing material containing lead in addition to tin. Objective.

  As a result of diligent research to solve the above-mentioned problems, the present inventors obtained a leaching solution containing tin by leaching a tin-containing powder or granule containing tin and lead in an aqueous caustic soda solution while oxidizing. Later, by using this leaching solution as an electrolytic solution and recovering tin by electrowinning, it was found that tin can be recovered inexpensively and efficiently from a tin-containing material containing lead in addition to tin. It came to complete.

  That is, in the method for recovering tin according to the present invention, a tin-containing powder or granular material containing tin and lead is leached while oxidizing in an aqueous caustic soda solution to obtain a leachate containing tin. It is characterized in that tin is recovered by electrowinning. In this tin recovery method, it is preferable to oxidize by blowing oxygen into an aqueous caustic soda solution. The tin-containing powder or granule containing tin and lead is preferably a powder or granule obtained from an alloy mass containing tin and lead, and the alloy mass containing tin and lead is atomized or pulverized. It is preferable to obtain a powder or a granular material. Further, the particle size of the tin-containing powder or granular material containing tin and lead is preferably 3 mm or less, and more preferably 1 mm or less. Further, the NaOH concentration in the aqueous caustic soda when leaching is completed is preferably 0.1 to 150 g / L, more preferably 4 to 80 g / L, and most preferably 30 to 80 g / L. preferable. Moreover, it is preferable that the temperature of the caustic soda aqueous solution in the case of leaching is 50-100 degreeC, and it is preferable that the temperature of the electrolyte solution in the case of electrowinning is 50-100 degreeC. Furthermore, it is preferable to add tin to the leachate to remove lead in the leachate before electrowinning.

  ADVANTAGE OF THE INVENTION According to this invention, the tin collection | recovery method which can collect | recover tin efficiently from the tin containing material containing lead etc. besides tin can be provided.

  Hereinafter, an embodiment of a method for recovering tin according to the present invention will be described with reference to FIG.

  First, when the tin-containing material containing tin (Sn) and lead (Pb) is in the form of a lump, it is refined to obtain a powder or granular material of the tin-containing material. In the case where the tin-containing material is an alloy lump containing tin and lead, metal powder is obtained by atomizing or grinding. The particle diameter of the tin-containing powder or granule is preferably 3 mm or less, and more preferably 1 mm or less.

  Next, the obtained tin-containing powder or granule is added to an aqueous caustic soda solution and stirred while blowing oxygen into the aqueous solution, and Sn is selectively leached by oxidative leaching. Note that Sn can be leached out by blowing air into the aqueous solution, but oxygen is preferably blown in order to prevent carbonation of NaOH.

  If the particle size of the tin-containing powder or granule is several mm or more, the leaching rate of Sn is slow even if oxygen is blown into the aqueous solution during the oxidative leaching, and the oxidative leaching takes a long time. , Pb leaching occurs before the Sn leaching rate exceeds 50%. In such a case, it is necessary to add an oxidizing agent such as hydrogen peroxide in order to obtain a sufficient leaching rate.

  The free NaOH concentration (initial concentration) in the aqueous caustic soda solution used for the leaching is preferably 10 to 200 g / L, and more preferably 50 to 100 g / L. When the free NaOH concentration in the aqueous caustic soda solution is low, Sn precipitates as an oxide during the leaching, and the leaching rate decreases. When the free NaOH concentration in the aqueous caustic soda solution is high, the solubility of Pb increases and the amount of Pb eluted increases. By increasing, the cost of liquid purification increases, the solubility of Sn decreases, and the current efficiency during electrowinning also deteriorates. The initial appropriate concentration of free NaOH (initial concentration) is the pulp concentration (g / L) after adding the tin-containing powder or granule to the aqueous caustic soda solution, the tin-containing powder or granule Therefore, it is better to define the free NaOH concentration at the end of leaching, and the free NaOH concentration at the end of leaching is preferably 0.1 g / L (pH 13) to 150 g / L. More preferably, it is 80 g / L, and most preferably 30-80 g / L.

  Further, the temperature of the aqueous solution at the time of leaching is preferably 50 to 100 ° C, and more preferably 70 to 90 ° C. When this temperature is low, elution of Pb starts before the end of Sn leaching, and when the temperature is high, the energy cost increases.

  In addition, after this leaching, Pb metal remains as a residue, and this Pb metal can be used as a lead smelting raw material.

  Next, Sn (powder, shot, plate, etc.) is introduced into the leachate containing Sn obtained by this leaching, and Pb in the leachate is removed by cementation.

Next, Sn metal is collect | recovered by electrowinning using the obtained liquid. In addition, the temperature of the liquid at the time of this electrowinning is preferably 50 to 100 ° C, and more preferably 70 to 90 ° C. If it is lower than 50 ° C., almost no electrodeposition is performed, and if it is lower than 70 ° C., current efficiency is deteriorated. Further, the post-electrolysis solution after electrolytically collecting Sn can be used repeatedly for Sn leaching because it regenerates the aqueous caustic soda solution by the following reaction.
Na ₂ [Sn (OH) ₄ ] → Sn + 2NaOH + H ₂ O + 0.5O ₂

  Examples of the method for recovering tin according to the present invention will be described in detail below.

[Example 1]
First, as shown in Table 1, an alloy lump having an Sn grade of 37.55%, a Pb grade of 58.48%, and an Sb (antimony) grade of 1.40% was atomized and then classified with a sieve having an opening of 150 μm. Got.

  Next, 56 g of this metal powder (alloy powder of Sn quality 37.55% (Sn 21.0 g), Pb quality 58.48% (Pb 32.7 g), Sb quality 1.40% (Sb 0.8 g)) was added with NaOH concentration. It was added to 700 mL of a 100 g / L aqueous solution of caustic soda to obtain a pulp concentration of 80 g / L. The temperature of this aqueous solution was set to 80 ° C., and oxygen leaching was performed by stirring with turbine blades while blowing oxygen into the aqueous solution. In this oxidation leaching, water is evaporated and the amount of liquid is reduced, so the reduced amount of water was added each time. The concentrations of Sn, Pb, and Sb in the liquid with respect to the leaching time are shown in FIG.

  As shown in FIG. 2, the Sn concentration in the liquid increased with the leaching time, but the Pb concentration hardly changed. Although the Sb concentration in the liquid increased with the leaching time, the Sb concentration was about 1 / 100th of the Sn concentration and was very low.

  This leaching was performed for 90 minutes, followed by filtration to obtain a leaching solution. As shown in Table 2, the concentrations (amounts) of Sn, Pb, Sb, and free NaOH contained in the obtained leachate were 29.32 g / L (20.5 g) and 0.72 g / L (0. 5%), 0.29 g / L (0.2 g), 79 g / L (55 g), and a leachate having a high Sn concentration and a low Pb concentration was obtained. The amount of leaching residue is 37.5 g, and the grades (amounts) of Sn, Pb and Sb contained in the leaching residue are 1.35% (0.51 g) and 85.98% (32.24 g), respectively. ), 1.54% (0.58 g). Moreover, the leaching rates of Sn, Pb, and Sb were 97.6%, 1.5%, and 26.2%, respectively.

  Next, Sn particles (99.9%) are added to the obtained leachate, and the mixture is stirred at 80 ° C. for 1 hour so as not to contain air on the liquid surface, and Pb and Sb are precipitated by a substitution reaction, followed by filtration. As a result, 700 mL of liquid (leaching liquid after substitution) was obtained. As shown in Table 3, the concentrations (amounts) of Sn, Pb, and Sb contained in the obtained post-substitution leachate were 31.05 g / L (21.7 g), <0.001 g / L, and. The liquid was 05 g / L (0.0 g) and contained almost no Pb.

Next, SUS304 was used as an anode and a cathode, and the obtained liquid was subjected to electrowinning at 80 ° C. and a current density of 100 A / m ^{3. As} shown in Table 4, the Sn quality, Pb quality, and Sb quality were < 19.9 g of 99.9%, <10 ppm, 125 ppm Sn metal was obtained.

  Moreover, as shown in Table 5, Sn, Pb, Sb, and free NaOH in 700 mL of the solution after electrolytic collection (post-electrolysis solution) were 8.7 g / L (4.9 g) and 0 g / L (0. 0 g), 0.015 g / L (0.0 g), and 91 g / L (64 g). It should be noted that water was evaporated during electrowinning and the amount of liquid was reduced, so the reduced amount of water was added each time.

  In addition, the post-electrolysis solution after electrolytically collecting Sn can be used for leaching of metal powder by adding consumption of NaOH.

[Examples 2 to 5]
As shown in Table 6, in Example 2, metal powder having a particle size of less than 150 μm (Sn grade 37.55%, Pb grade 58.48%, Sb grade 1.40%), and in Example 3, particle size 150 to 400 μm. Metal powder (Sn grade 37.94%, Pb grade 58.23%, Sb grade 1.38%), in Example 4, metal powder having a particle size of 400 μm to 1 mm (Sn grade 37.94%, Pb grade 58. 23%, Sb grade 1.38%), and in Example 5, metal powder having a particle size of 1.7 to 3 mm (Sn grade 49.12%, Pb grade 49.17%, Sb grade 1.32%) was prepared. These metal powders were subjected to the same oxidative leaching as in Example 1 except that an aqueous caustic soda solution having a NaOH concentration of 50 g / L was used and the temperature of the aqueous solution was 60 ° C. The leaching rates of Sn and Pb with respect to the leaching time are shown in FIGS. 3 and 4, respectively. In Examples 2 to 5, the NaOH concentrations in the aqueous caustic soda solution at the end of leaching were 28.6 g / L, 29.3 g / L, 33.0 g / L, and 35.9 g / L, respectively.

  As shown in FIGS. 3 and 4, in Examples 2 to 4, it was possible to obtain a very high Sn leaching rate in a short time and to suppress the Pb leaching rate. Further, in Example 5, when the leaching time was about 400 minutes, an Sn leaching rate of about 50% could be obtained, and the Pb leaching rate could be suppressed.

[Examples 6 and 7]
About the metal powder (Sn grade 37.55%, Pb grade 58.48%, Sb grade 1.40%) similar to Example 2 with a particle size of less than 150 μm, NaOH concentrations of 100 g / L (Example 6) and 25 g, respectively. The same oxidative leaching as in Example 2 was performed except that an aqueous caustic soda solution of / L (Example 7) was used. In Examples 2, 6 and 7, the concentrations of Sn and Pb in the leachate with respect to the leaching time are shown in FIGS. 5 and 6, respectively. In Examples 6 and 7, the NaOH concentrations in the aqueous caustic soda solution at the end of leaching were 74.9 g / L and 7.6 g / L, respectively.

  As shown in FIGS. 5 and 6, in Example 6, the concentrations of Sn, Pb and free NaOH in the leachate obtained after leaching for 90 minutes were 30.2 g / L and 13.9 g / L, respectively. 75 g / L. In Example 6, the Sn leaching rate could be almost 100% higher than that of Example 2, but the Pb leaching rate was 29.7%, and the Pb leaching rate was higher than that of Example 2. It became high. The concentrations of Sn and Pb in the leachate obtained after leaching for 60 minutes were 28.85 g / L (leaching rate 96%) and 1.49 g / L (leaching rate 3.2%), respectively. If the leaching is stopped after 60 minutes, the leaching of Sn can be almost completed before the leaching of Pb starts.

  In Example 7, the concentrations of Sn, Pb and free NaOH in the leachate obtained after leaching for 90 minutes were 24.22 g / L, 0.09 g / L and 7.6 g / L, respectively. It was. In Example 7, the Sn leaching rate was about 80%, but the Pb leaching rate could be suppressed to 0.2%. In addition, the cloudy deposit considered to be metastannic acid was produced in the leachate.

  Further, comparing Example 1 in which oxidative leaching was performed at 80 ° C. and Example 6 in which oxidative leaching was performed in the same manner as in Example 1 except that the leaching temperature was 60 ° C., both were leached for 90 minutes. Although the Sn leaching rate could be increased, the Pb leaching rate was higher in Example 6 than in Example 1. However, in Example 6, as described above, if leaching is stopped after 60 minutes, the leaching of Sn can be almost completed before the leaching of Pb starts.

It is process drawing which shows embodiment of the recovery method of the tin by this invention. It is a graph which shows the density | concentration of Sn in a liquid with respect to leaching time in Example 1, and Pb. It is a graph which shows the leaching rate of Sn with respect to leaching time in Examples 2-5. It is a graph which shows the leaching rate of Pb with respect to leaching time in Examples 2-5. It is a graph which shows the density | concentration of Sn in the leaching solution with respect to the leaching time in Examples 2, 6 and 7. It is a graph which shows the density | concentration of Pb in the leaching solution with respect to the leaching time in Examples 2, 6 and 7.

Claims (12)

A tin-containing powder or granule containing tin and lead is leached while oxidizing in an aqueous caustic soda solution to obtain a leachate containing tin, and then the tin is recovered by electrowinning using this leachate as an electrolyte. A method for recovering tin, which is characterized by the above. The method for recovering tin according to claim 1, wherein the oxidation is performed by blowing oxygen into the aqueous caustic soda solution. 3. The recovery of tin according to claim 1, wherein the powder or granule of the tin-containing material containing tin and lead is a powder or granule obtained from an alloy lump containing tin and lead. Method. 4. The method for recovering tin according to claim 3, wherein the tin-containing powder or granular material containing tin and lead is obtained by atomizing or pulverizing the alloy lump containing tin and lead. 5. 5. The method for recovering tin according to claim 1, wherein the tin-containing powder or granular material containing tin and lead has a particle size of 3 mm or less. 5. The method for recovering tin according to claim 1, wherein the tin-containing powder or granular material containing tin and lead has a particle size of 1 mm or less. The method for recovering tin according to any one of claims 1 to 6, wherein a NaOH concentration in the aqueous caustic soda solution when the leaching is finished is 0.1 to 150 g / L. The method for recovering tin according to any one of claims 1 to 6, wherein the NaOH concentration in the aqueous caustic soda solution when the leaching is finished is 4 to 80 g / L. The method for recovering tin according to any one of claims 1 to 6, wherein a NaOH concentration in the aqueous caustic soda solution when the leaching is completed is 30 to 80 g / L. The method for recovering tin according to any one of claims 1 to 9, wherein the temperature of the aqueous caustic soda solution during the leaching is 50 to 100 ° C. The method for recovering tin according to any one of claims 1 to 10, wherein the temperature of the electrolytic solution during the electrowinning is 50 to 100 ° C. The method for recovering tin according to any one of claims 1 to 11, wherein tin is added to the leachate to remove lead in the leachate before the electrowinning.

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