Method for separating tin and antimony

Abstract

To provide a processing method capable of efficiently separating stannum and antimony contained in silver-lead-containing slag or the like from the slag.SOLUTION: A separation method of stannum and antimony is characterized by leaching a lead-chloride-containing substance containing stannum and antimony with sulfuric acid of a concentration of 3M-8M to separate a liquid containing stannum and antimony by solid-liquid separation. The lead-chloride-containing substance is, for instance, silver-lead-containing slag or the like obtained by removing copper from copper electrolytic slime. Preferably, the pulp concentration of the slurry leached by sulfuric acid is 300 g / L-1,000 g / L and the sulfuric acid leaching temperature is 30°C-90°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a treatment method for efficiently separating tin and antimony contained in a silver-lead-containing slag obtained by wet chlorination of copper electrolytic slime from the slag. [Background technology]

[0002] A known method involves decopperizing copper electrolytic slime and then subjecting it to a chlorination leaching process to leach gold, platinum group elements, selenium, and tellurium, separating silver chloride and lead chloride as leach slag, and recovering silver from the leach slag.Specifically, for example, a known method involves repulping the chlorination leach precipitate of copper electrolytic slime with water, adding iron powder, simultaneously reducing silver and lead to remove chlorine, thereby precipitating metallic silver and lead, melting this mixture in an oxidation furnace, oxidizing the lead to form slag, and separating and recovering crude metallic silver (Patent Document 1).

[0003] Also known is a method for recovering silver from a silver-lead-containing material, which includes a step of slurrying a raw material containing silver-lead chloride with dilute sulfuric acid, adding iron powder to the slurry to reduce the silver chloride and precipitate metallic silver (silver reduction step using iron powder), a step of adding sulfuric acid to the slurry to convert the lead chloride to lead sulfate, which is precipitated, and recovering a mixture containing metallic silver and lead sulfate (lead sulfate formation step), a step of reducing and smelting this mixture to form a metal containing silver and a slag containing lead sulfate, and separating the metal and slag (reduction smelting step), and a step of oxidizing and smelting the recovered metal to obtain crude silver (oxidation smelting step) (Patent Document 2).

[0004] Further, there are known silver recovery methods including a nitric acid leaching process in which a silver-lead chloride raw material containing tin is carbonated to convert the lead chloride to lead carbonate, and then nitric acid is added to selectively leach the lead carbonate and perform solid-liquid separation; a hydrochloric acid leaching process in which strong hydrochloric acid is added to the nitric acid leach slag to leach out the bismuth and antimony contained in the raw material and perform solid-liquid separation; an iron reduction process in which sulfuric acid is added to the hydrochloric acid leach slag, and then iron powder is added to reduce the silver chloride in the hydrochloric acid leach slag to form crude silver; and an oxidation refining process in which soda silicate slag is added to the iron reduction slag, and the slag is oxidized and melted, and the tin and impurities are absorbed by the slag, thereby separating and recovering crude silver (Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-317636 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-190135 [Patent Document 3] Japanese Patent Publication No. 2020-132957 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, copper smelters have actively processed recycled scrap, resulting in higher concentrations of tin and antimony in copper electrolytic slime. Tin and antimony are difficult to dissolve in chloride leaching, and tend to concentrate in chloride leach slag along with silver chloride and lead chloride. Furthermore, when tin and antimony are heated with lead, they form complex oxides with high melting points, which are difficult to melt in dry processing. Furthermore, in dry processing, an increase in the concentration of unmelted material increases the apparent viscosity of the slag, resulting in adverse effects such as silver entrapment loss in the slag and a deterioration in the fluidity of the slag. Therefore, it is necessary to separate tin and antimony before dry processing.

[0007] The present invention provides a treatment method for efficiently separating tin and antimony contained in silver-lead-containing slag from the slag. [Means for solving the problem]

[0008] The present invention provides a method for separating tin and antimony that solves the above problems by the following configuration. (1) A method for separating tin and antimony, which comprises leaching a material containing lead chloride containing tin and antimony with sulfuric acid having a concentration of 3M to 8M, and separating the liquid containing tin and antimony into solid and liquid components. (2) The method for separating tin and antimony according to the above [1], wherein the pulp concentration of the sulfuric acid leaching slurry of the lead chloride-containing material is 300 g / L to 1000 g / L. (3) The method for separating tin and antimony according to the above [1] or [2], wherein the sulfuric acid leaching temperature of the lead chloride-containing material is 30°C to 90°C.

[0009] [Specific explanation] The processing method of the present invention will now be described in detail. The treatment method of the present invention is a method for separating tin and antimony, characterized by leaching a lead chloride-containing material containing tin and antimony with sulfuric acid having a concentration of 3M to 8M, and subjecting the liquid containing tin and antimony to solid-liquid separation.

[0010] In the treatment method of the present invention, the lead chloride-containing material containing tin and antimony is, for example, a silver-lead-containing slag obtained by decopperizing copper electrolytic slime and then subjecting it to chlorination leaching to leach gold, platinum group elements, selenium, and tellurium, and containing silver chloride and lead chloride as residues. The silver-lead-containing slag contains lead chloride as well as tin and antimony.

[0011] In the treatment method of the present invention, lead chloride-containing material containing tin and antimony is leached using sulfuric acid with a concentration of 3M to 8M. For example, in the case of the silver-lead-containing slag, as shown in the following formula (1), the lead chloride contained in the slag reacts with sulfuric acid to form lead sulfate and hydrogen chloride. Furthermore, the tin oxide contained in the slag reacts with the hydrogen chloride to form a tin chloride complex (HSnCl6) as shown in the following formula (2), and the antimony oxide contained in the slag reacts with the hydrogen chloride to form an antimony chloride complex (HSbCl5) as shown in the following formula (3), which then dissolves into the solution.

[0012] PbCl3+ H2SO4→ PbSO4+ 2HCl ··· (1) SnO2+6HCl → H2SnCl6+ 2H2O ··· (2) Sb2O3+10HCl → 2H2SbCl5+ 3H2O ···(3)

[0013] If the sulfuric acid concentration is lower than 3M, the leaching effect of tin and antimony is low. On the other hand, if the sulfuric acid concentration is higher than 8M, the generated hydrogen chloride evaporates, and the reaction between tin oxide and antimony oxide and hydrogen chloride becomes insufficient, resulting in a decrease in the leaching effect of tin and antimony.

[0014] The silver chloride contained in the silver-lead-containing slag is not sulfated during the sulfuric acid leaching. Because lead chloride has a higher solubility in water than lead sulfate (lead chloride > lead sulfate), lead chloride dissolves and lead sulfate precipitates, resulting in the production of lead sulfate. However, because silver chloride has a lower solubility in water than silver sulfate (silver sulfate > silver chloride), the reaction from silver chloride to silver sulfate hardly progresses.

[0015] Thus, in the sulfuric acid leaching, the presence of lead chloride promotes the leaching of tin and antimony. Normally, the amount of lead chloride contained in the chlorine leaching slag after copper removal from copper electrolytic slime is greater than the amount of tin or antimony, so the above reaction proceeds sufficiently with the chlorine dissolved from the lead chloride in the slag alone.

[0016] The pulp concentration of the sulfuric acid leaching slurry of the lead chloride-containing material is preferably in the range of 300 g / L to 1000 g / L, more preferably 500 g / L to 1000 g / L. If the concentration is less than 300 g / L, the amount of chlorine dissolved is small, and the leaching of tin and antimony does not proceed sufficiently. On the other hand, if the concentration exceeds 1000 g / L, the viscosity of the slurry increases, making it difficult to uniformly stir the entire slurry, which is undesirable.

[0017] The sulfuric acid leaching temperature is preferably 30°C to 90°C, more preferably 60°C to 80°C. If the leaching temperature is below 30°C, the reaction rate is slow and the leaching time is long. If the leaching temperature is higher than 90°C, the amount of evaporation of the solution increases, which is not preferable.

[0018] After the sulfuric acid leaching, solid-liquid separation can be performed to separate the tin and antimony contained in the liquid from the silver and lead contained in the leaching residue. The tin and antimony contained in the liquid can be easily recovered by neutralizing and precipitating them. Furthermore, since antimony precipitates on the acidic side during this neutralization, by first performing solid-liquid separation on the precipitated antimony, it can be separated from the tin that precipitates during subsequent neutralization. [Effects of the Invention]

[0019] According to the treatment method of the present invention, tin and antimony can be selectively leached with sulfuric acid from lead chloride-containing materials containing tin and antimony, such as the silver-lead-containing slag, without eluting lead or silver. Sulfate complexes of tin and antimony are usually difficult to form because they are unstable, but in the treatment method of the present invention, since lead chloride is also present, chlorine is dissolved into the solution by the sulfation of lead chloride, and this chlorine forms chloride complexes of tin and antimony, resulting in stable elution of tin and antimony.

[0020] Since sulfuric acid is produced as a by-product of copper smelting, it can be carried out at low cost if it is carried out in connection with copper smelting. Furthermore, although chlorine leach slag is usually desalted before dry treatment, the treatment method of the present invention simultaneously separates tin and antimony and dechlorinates lead chloride, thereby reducing the burden of desalting treatment.

[0021] The treatment method of Patent Document 2 also includes a sulfation step, but it is carried out after the silver reduction step. If reduction is carried out before sulfation, tin and antimony are also reduced, making them difficult to leach with sulfuric acid. The treatment method of the present invention, in which the chlorinated leach sludge is first leached with sulfuric acid, is more suitable for separating tin and antimony.

[0022] In the processing method of Patent Document 3, the chloride leach slag is carbonated, followed by nitric acid leaching to leach lead, and then concentrated hydrochloric acid leaching to leach bismuth and antimony. However, leaching with concentrated hydrochloric acid not only leaches tin and antimony, but also slightly leaches silver and lead, resulting in a loss of silver and lead. Furthermore, sulfuric acid leaching is less expensive than concentrated hydrochloric acid leaching. DETAILED DESCRIPTION OF THE INVENTION

[0023] Examples of the present invention are shown below. The residue of each sample was analyzed by XRF (X-ray fluorescence analysis), and each solution was analyzed by ICP.

[0024] [Example] To 30 g of chlorinated leachate with the composition shown in Table 1, 60 mL of 6.5 M sulfuric acid (Sample No. A1) or 60 mL of 5.0 M sulfuric acid (Sample No. A2) was added to prepare a slurry with a pulp concentration of 500 g / L. Additionally, 6 g of chlorinated leachate was added to prepare a slurry with a pulp concentration of 100 g / L (Sample No. A3). The pulp concentration was calculated as the mass of chlorinated leachate (g) divided by the amount of sulfuric acid added (L). These samples were leached at 75°C for 24 hours, followed by solid-liquid separation. The leachate was analyzed by ICP, and the leachate by XRF. The leaching rate of each element was calculated based on the analytical values. The results are shown in Table 2.

[0025] Comparative Example Leaching was carried out in the same manner as Sample No. 1, except that 2.0 M sulfuric acid was used (Sample No. B1). Leaching was carried out in the same manner as Sample No. 1, except that 9.0 M sulfuric acid was used (Sample No. B2). Leaching was carried out in the same manner as Sample No. 1, except that 8.0 M hydrochloric acid was used (Sample No. B3). These leachates and leach slag were analyzed in the same manner as Sample No. 1 to determine the leaching rate of each element. The results are shown in Table 2.

[0026] As shown in Table 2, in both samples A1 and A2, almost no silver or lead was eluted, while Sn and Sb were selectively leached. Furthermore, the leaching rate of Sb in sample A3 was slightly reduced, so a pulp concentration of 100 g / L or higher is preferable for the slurry. This is thought to be because the concentration of chlorine dissolved in the solution varies depending on the pulp concentration. In sulfuric acid leaching, chlorine dissolves from lead chloride into the solution, as shown in equation (1) above. The higher the pulp concentration, the more efficiently this reaction proceeds, resulting in a higher chlorine concentration in the solution. Sn and Sb do not easily form sulfate complexes, but rather tend to form chloride complexes as shown in equations (2) and (3) above, so a higher chlorine concentration makes them more soluble. A higher pulp concentration increases the chlorine concentration, and so does the leaching rate of Sn and Sb.

[0027] On the other hand, sample No. B1, which was prepared using 2.0M sulfuric acid, showed a low Sn leaching rate and a significant drop in the Sb leaching rate. Furthermore, sample No. B2, which was prepared using 9.0M sulfuric acid, showed a low Sn leaching rate and a low Sb leaching rate. These results suggest that the sulfuric acid concentration should be higher than 2.0M but lower than 9.0M. With 2.0M sulfuric acid, the leaching reactions of the above equations (2) and (3) do not proceed sufficiently. On the other hand, when 9.0M sulfuric acid was used, white smoke from hydrogen chloride was observed during leaching. At high sulfuric acid concentrations, some of the hydrogen chloride evaporated without remaining dissolved in the solution. This evaporation of hydrogen chloride is thought to lower the chlorine concentration in the solution, reducing the leaching rates of Sn and Sb.

[0028] Sample No. B3, which was prepared using 8.0M hydrochloric acid, had a high Sb leaching rate, but Ag and Pb were also leached, so it is not suitable for separating Sn and Sb from Ag and Pb. Although chlorides of Ag and Pb are sparingly soluble, they are dissolved in high-concentration hydrochloric acid [AgCl2] + and [PbCl4] 2+ This is thought to be because the compound forms a complex and dissolves.

[0029] [Table 1]

[0030] [Table 2]

Claims

1. A method for separating tin and antimony, comprising leaching a lead chloride-containing material containing tin and antimony with sulfuric acid having a concentration of 3M to 8M, and separating the liquid containing tin and antimony into solid and liquid components.

2. 2. The method for separating tin and antimony according to claim 1, wherein the pulp concentration of the sulfuric acid leaching slurry of the lead chloride-containing material is 300 g / L to 1000 g / L.

3. 3. The method for separating tin and antimony according to claim 1, wherein the temperature of sulfuric acid leaching of the lead chloride-containing material is 30°C to 90°C.

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