JP2019173134A - MANUFACTURING METHOD OF Sn - Google Patents

Abstract

To provide a manufacturing method of Sn capable of reducing Sn concentration in Sn.SOLUTION: A manufacturing method of Sn includes an Sb deposition process for adding Sn metal to a Sn electrolyte obtained by conducting exudation and purification on Sn scum containing Sb, and depositing the Sb by a cementation reaction, and Sn deposition process for depositing Sn by conducting electrolytic extraction on the Sn electrolyte after the Sb deposition process.SELECTED DRAWING: Figure 4

Description

  This case relates to a manufacturing method of Sn.

  For example, tin (Sn) scum is generated in lead smelting for producing a product Pb from a lead raw material such as lead (Pb) soot generated in copper smelting or the like. When Sn scum is subjected to the leaching step, Sn elutes in the leaching solution. A Sn ingot can be manufactured from electrodeposited Sn obtained by performing electrowinning on the obtained liquid after leaching (see, for example, Patent Document 1).

JP 2013-234356 A

  However, when antimony (Sb) is contained in the Sn scum, the Sb concentration in the Sn ingot may be increased.

  In view of the above-described problems, an object of the present invention is to provide a method for producing Sn that can reduce the Sb concentration in Sn.

  In one aspect, the manufacturing method of Sn adds Sn metal to Sn electrolytic solution obtained by leaching and purifying Sn scum containing Sb, and deposits Sb by a cementation reaction. It includes a precipitation step and a Sn precipitation step of depositing Sn by performing electrowinning on the Sn electrolytic solution after the Sb precipitation step.

  The Sb concentration in Sn can be reduced.

It is a figure explaining an example of the process of manufacturing Sn and Pb. It is a figure which illustrates cementation. It is a figure which shows the measurement result of the time change of Sb density | concentration in Sn electrolyte solution. It is a figure explaining an example of the process of manufacturing Sn. It is a figure which shows the relationship between the elapsed time after adding Sn metal, and Sb density | concentration in Sn electrolyte solution.

  Hereinafter, an embodiment for carrying out the present invention will be described.

  FIG. 1 is a diagram illustrating an example of a manufacturing process for manufacturing the product Sn and the product Pb. As illustrated in FIG. 1, copper removal and carbonation are performed on lead raw materials such as lead soot generated in a copper smelting process and the like, and an exhaust battery. Lead carbonate obtained by copper removal and carbonation is put into a Pb electric furnace as a Pb raw material. Lead carbonate is separated into crude Pb metal and slag by melting at 1000 ° C. to 1200 ° C. in a lead electric furnace.

The crude Pb metal contains Sn as an impurity. Therefore, the cooled crude Pb metal is put into a Harris furnace. In the Harris furnace, the crude Pb metal is soda-treated. In the soda treatment, for example, caustic soda is added to the crude Pb metal heated to about 500 ° C. and melted, and additional caustic soda and sodium nitrate are optionally added to convert Sn into a soda salt (Na ₂ SnO ₃ ). This is a treatment for solidifying the molten metal surface. Solidified soda salt of Sn is generally called Sn scum. As an example, Sn scum contains 10 mass% to 30 mass% of Sn, 5.0 mass% to 20 mass% of Pb, 2 mass% to 15 mass% of Sb, and 0.5 mass% to 5 mass% of Cu in a dry state. 0 mass% is contained, As is contained 1.0 mass% to 10 mass%, and Bi is contained 0.5 mass% to 7.0 mass%.

  Sn scum is used as a Sn raw material for producing product Sn. Specifically, the Sn scum is subjected to a Sn leaching process for leaching Sn. The leached filtrate obtained by filtering the obtained leached solution is subjected to the Sn electrowinning step and used as the Sn electrolytic solution. The Sn concentration in the Sn electrolytic solution is, for example, 10 g / L to 70 g / L. Moreover, Sb density | concentration in Sn electrolyte solution is 10 mg / L-200 mg / L, for example. A Sn ingot is produced from electrodeposited Sn obtained from the Sn electrolytic solution in the Sn electrowinning step. The leaching residue of the Sn leaching process is repeated in the lead electric furnace or the carbonation process. On the other hand, Pb metal is obtained by soda processing the crude Pb metal in a Harris furnace. This Pb metal is subjected to an electrolytic purification process to produce a product Pb.

  Since the Sn electrolytic solution contains Sb, the Sn ingot may also contain Sb. In order to further purify the Sn ingot, the Sb concentration in the Sn ingot is preferably low. For example, a concentration of 500 ppm or less is desired as a product standard for Sn ingots. Therefore, the present inventors paid attention to a cementation reaction in the Sn electrowinning process.

In the Sn electrowinning process, electrodeposited Sn is deposited. The deposited electrodeposited Sn comes into contact with the Sn electrolytic solution. Since Sn scum contains Sb, the Sn electrolytic solution contains Sb ions (Sb ³⁺ ). Since the ionization tendency of Sn is higher than the ionization tendency of Sb, as shown in FIG. 2, when electrodeposited Sn comes into contact with the Sn electrolytic solution containing Sb ³⁺ , the electrodeposition is represented by the following formula (1). Sn is dissolved as Sn ²⁺ , and Sb ³⁺ is precipitated as electrodeposited Sn as Sb.
3Sn + 2Sb ³⁺ = 3Sn ²⁺ + 2Sb (1)

The inventors conducted a beaker test. Plate-shaped Sn metal was immersed in an Sn electrolytic solution containing Sb ^3+, and the change with time in the Sb concentration in the Sn electrolytic solution was measured. FIG. 3 is a diagram showing the measurement results. As shown in FIG. 3, the Sb concentration in the Sn electrolytic solution was higher than 120 mg / L before the Sn metal was immersed, whereas the Sb concentration decreased with time. From the above results, it was confirmed that when Sn metal comes into contact with the Sn electrolytic solution containing Sb ³⁺ , Sb precipitates on the Sn metal.

Therefore, in this embodiment, as illustrated in FIG. 4, Sn metal is added to the Sn electrolytic solution before being energized in the electrowinning process. Thereby, a cementation reaction occurs, Sb precipitates on the Sn metal, and Sb ³⁺ in the Sn electrolytic solution can be removed. By performing the Sn electrowinning process after removing the Sn metal on which Sb is deposited, electrodeposited Sn with a low Sb concentration can be obtained, and an Sn ingot with a low Sb concentration can be produced.

In addition, it is preferable that the time required for removal of Sb ³⁺ in the Sn electrolytic solution is short. Therefore, it is conceivable to increase the amount of Sn metal added. However, when the amount of Sn metal added is large, it may be difficult to charge the reaction vessel in the Sb deposition step. Therefore, it is preferable that the amount of Sn metal added is small. Therefore, it is preferable to add Sn metal having a high specific surface area such as chip-like Sn metal. By using Sn metal having a high specific surface area, the surface area of Sn metal is increased. Thereby, the cementation reaction is promoted, and the time required for the removal of Sb ³⁺ in the Sn electrolyte solution can be shortened. Moreover, since a sufficient surface area is ensured even if a relatively small amount of Sn metal is used, the amount of Sn metal added can be suppressed. For example, it is preferable to use Sn metal having a specific surface area of 20 cm ² / g or more.

Here, as a result of conducting an Sb precipitation removal test using Sn metals having different surface areas, a result of Sb precipitation rate = 33.2 mg / min / m ² was obtained. Assuming an actual machine, if Sb is sufficiently removed from the electrolytic solution having a liquid volume of 60 m ³ and an Sb concentration of 120 mg / L, it is necessary to add Sn metal having a surface area of 1800 m ^{2 in} a reaction time of 2 hours. On the other hand, in 10 hours, it is necessary to add Sn metal having a surface area of 360 m ² . If a large amount of Sn metal can be added, Sb can be removed in a short time. When removing Sb with addition of a small amount of Sn metal, the reaction time may be lengthened.

(Examples 1 and 2)
Sn metal was added to the Sn electrolytic solution, and the time change of the Sb concentration in the Sn electrolytic solution was measured. In both Examples 1 and 2, the amount of the Sn electrolytic solution was 400 ml. The temperature of the Sn electrolytic solution was maintained at 65 ° C to 70 ° C. In Example 1, an Sn electrolytic solution having an Sn concentration of 68.6 g / L and an Sb concentration of 115.3 mg / L was used. In Example 2, an Sn electrolytic solution having an Sn concentration of 51.7 g / L and an Sb concentration of 124.5 mg / L was used. used. In Example 1, as Sn metal, plate-like Sn (weight: 33.4 g, surface area: 49.7cm ^2, specific surface area: 1.5cm ² / g) was used. In Example 2, as the Sn metal, chip-like Sn (weight: 7.0 g, surface area: 142.9 cm ² , specific surface area: 20.4 cm ² / g) was used.

FIG. 5 is a diagram showing the relationship between the elapsed time since the addition of Sn metal and the Sb concentration in the Sn electrolyte solution. As shown in FIG. 5, in both Examples 1 and 2, the Sb concentration in the Sn electrolytic solution gradually decreased with time. From this result, it was confirmed that Sb was removed from the Sn electrolytic solution by adding Sn metal to the Sn electrolytic solution containing Sb ³⁺ . If Sn electrolysis is performed using the Sn electrolytic solution from which Sb has been removed, Sn having a low Sb concentration can be produced.

Moreover, from the result of FIG. 5, it was confirmed that the cementation reaction can be promoted by increasing the surface area of the Sn metal. In addition, it was confirmed that the amount of Sn metal added can be reduced by using a chopped Sn metal having a high specific surface area. From the comparison result between Example 1 and Example 2, it was confirmed that the specific surface area of Sn metal is preferably 20 cm ² / g or more.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

Claims (5)

An Sb precipitation step of adding Sn metal to a Sn electrolytic solution obtained by leaching and purifying Sn scum containing Sb and precipitating the Sb by a cementation reaction;
And a Sn deposition step of depositing Sn by performing electrowinning on the Sn electrolyte solution after the Sb deposition step.   The method for producing Sn according to claim 1, wherein the Sn metal is chip Sn. The method for producing Sn according to claim 1 or 2, wherein a specific surface area of the Sn metal is 20 cm ² / g or more.   The Sn manufacturing method according to any one of claims 1 to 3, wherein a Sn concentration in the Sn electrolytic solution before the Sb deposition step is 10 g / L to 70 g / L.   The method for producing Sn according to any one of claims 1 to 4, wherein an Sb concentration in the Sn electrolytic solution before the Sb deposition step is 10 mg / L to 200 mg / L.

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