KR20120127274A - A method for recovering tin from arsenic-containing solution - Google Patents

Abstract

PURPOSE: A method for recovering tin from arsenic-containing solution is provided to prevent the production of arsine gas by maintaining Sn concentration of 10g/l or greater in tin electrolyte including at least arsenic. CONSTITUTION: According to a method for recovering tin from arsenic-containing solution, tin electrolytic sample liquid containing at least arsenic is electrolyzed in a condition not causing hydrogen at a tin concentration of 10g/l. The electrolysis is stopped at a tin concentration over 10g/l, and the liquid obtained through the electrolysis is maintained with an ORP value of -200 mV(vs AgCl/Ag) or greater. If the ORP value of the liquid is less than -200 mV, an oxidizing agent is added and pH is lowered to obtain some arsenic dissolved in the liquid. [Reference numerals] (AA) Sn scum; (BB) Leaching process; (CC) Hot water + caustic soda; (DD) Residue(Pb,Sb); (EE) Liquid after leaching(Sn:30-50g/L); (FF) Adding hydrosulfide soda; (GG) Sulfide(Pb,Cu); (HH) Sulfiding process; (II) Liquid after sulfiding(Sn:30-50g/L); (JJ) Electrowinning; (KK) Liquid after electrolysis(Sn:10-15g/L); (LL) Neutralizing process; (MM) Sn neutralized material; (NN) Sn electrodeposition metal(current effect of 90% or greater); (OO) Liquid after neutralizing(adding oxidizer incase of ORP lower than -200mV); (PP) Draining process; (QQ) Resultant material(containing As); (RR) Removing As

Description

Recovery method of tin from arsenic-containing solution {A METHOD FOR RECOVERING TIN FROM ARSENIC-CONTAINING SOLUTION}

The present invention relates to a method for recovering tin from an arsenic containing solution.

Conventionally, sulfuric acid is leached by sulfuric acid to recover lead contained in a dry banquet of nonferrous metal smelting from a melting furnace of recycled raw materials such as non-ferrous smelting, infrastructure and electronic parts, and a dry furnace for melting and processing industrial waste. After making it lead, melt reduction is performed in an electric furnace.

The metal separated by the melt reduction is subjected to soda treatment, anodized, and electrolytically purified using a silicic acid bath or the like. By this electrolytic purification, the electrical lead is recovered. On the other hand, tin is recovered in the soda scum generated during the soda treatment.

Arsenic is also mixed in this soda scum, and the preferable process is calculated | required from a viewpoint of handling arsenic.

As a method for recovering such tin, for example, Japanese Unexamined Patent Application Publication No. Hei 4-191340 (Patent Document 1) discloses tin compounds such as Na ₂ SnO ₃ , SnO ₂ , and SnO leached with water, an alkaline solution, or the like. Then, after removing lead and copper eluted by sulfidation, the method of carrying out electrolytic collection and collecting as electrodeposition metal is disclosed.

Japanese Unexamined Patent Publication No. 4-191340

However, in Patent Literature 1, when a tin compound is leached with water or an alkali, it is eluted together with tin to arsenic, so arsenic is mixed in the electrolytic extracting liquid, and arsine gas, which is a harmful substance, is generated during electrolytic collection of tin. There was a problem.

Therefore, an object of the present invention is to provide a method for safely and efficiently recovering tin from tin electrolytic extracting liquid containing arsenic.

MEANS TO SOLVE THE PROBLEM This inventor completed the following invention as a result of earnestly examining in order to solve the said subject.

(1) A method for recovering tin from an arsenic-containing solution, wherein the tin electrolytic sampling liquid containing at least arsenic is electrolytically treated under conditions such that no hydrogen is generated.

(2) The method according to (1), wherein the electrolytic treatment is performed at a tin concentration of 10 g / l or more.

(3) The method according to (1) or (2), wherein the electrolytic treatment is stopped at a tin concentration of 10 g / l or more, and the ORP value is -200 mV for the electrolytic liquid obtained by the electrolytic treatment. (vs AgCl / Ag) or higher, or when the ORP value is lower than -200 mV, at least a part of arsenic is electrolyzed by adding an oxidizing agent, adjusting it to -200 mV or higher, and then lowering the pH. And a process for changing tin into the form of Sn neutralized while being dissolved in water.

(4) In the method described in (3), the Sn neutralization is further solid-liquid separated, the Sn (OH) ₄ is re-dissolved in the solution of electrolytic collection, and tin is recovered by electrolytic treatment. Way.

(5) (1) The method according to any one of (4), wherein the tin electrolytic extracting solution is a step of leaching a caustic soda scum obtained by soda treatment with a caustic soda aqueous solution, followed by a step of sulfiding the liquid after leaching. Electrolytic sampling method of tin which is a liquid after sulfidation obtained through the process.

(6) The method according to (3), wherein the oxidizing agent is hydrogen peroxide.

According to the present invention, it is possible to provide a method for safely and efficiently recovering tin from a tin electrolytic extracting liquid containing arsenic. More specifically,

(1) By controlling the Sn concentration in the tin electrolytic solution containing at least arsenic at 10 g / L or more, generation of arsine gas can be prevented.

(2) Tin in an arsenic-containing liquid can be recovered efficiently without an environmental problem at the factory.

1 shows a method of treating tin scum, which is one embodiment of the present invention.
2 shows the concentrations of As and Sn in the liquid at pH changes.
3 shows the residual ratios of As and Sn in the liquid at pH change.

EMBODIMENT OF THE INVENTION Below, embodiment of the recovery method of tin from the arsenic containing solution which concerns on this invention is described.

The treatment target of the method of the present invention is a tin electrolyte containing at least arsenic and containing tin. These solutions are obtained, for example, when recovering tin contained in the soda scum obtained by carrying out soda treatment.

After a soda treatment, the scum usually has a comment of 15? 40 mass%, Arsenic 0.5? 10 mass%, lead 40? 50 mass%, copper is 5? 10 mass%, antimony is 0.3? It contains about 2 mass%.

The scum has a slurry concentration of 150? It is 350 g / L, and can be leached with the liquid which dissolved caustic soda in hot water. In terms of leaching efficiency, the temperature of hot water is 60? 80 degreeC is preferable. The slurry concentration is adjusted so that the tin concentration in the liquid after leaching is 10 g / l or more. In the residue at the time of leaching, lead and antimony are removed.

In the liquid after leaching, tin is typically 25? 60 g / l, Arsenic 5? 10 g / l is dissolved. It is preferable to add sulfiding agent, for example, sodium sulfide, hydrogen sulfide gas, etc. to the solution, and to sulfide, and to remove lead and copper as sulfides.

The liquid after sulfidation after sulfidation generally has a pH of 10 or more, preferably 10? 14, more preferably 13? 14, which can be used as a tin electrolytic solution. Using this electrolytic sampling liquid, current density: 50? 100 A / ㎡, liquid temperature: 50? Sn electrodeposition metal is collect | recovered by electrolytic treatment at 80 degreeC.

Here, generation | occurrence | production of arsine gas can be suppressed by maintaining Sn density | concentration in tin electrolytic extract liquid at 10 g / or more. In addition, it is preferable to maintain the Sn concentration in the tin electrolytic extract liquid at 30 g / l or more in order to obtain high current efficiency.

In addition, when providing the liquid to the wastewater treatment after electrolysis, it is preferable to recover tin from the electrolytic sampling liquid as much as possible. In other words, when the amount of tin dissolved at the electrolytic picking end increases, that is, the Sn concentration in the tin electrolytic picking liquid at the electrolytic picking end is high, the direct rate of tin is lowered.

In view of the above, the tin concentration is generally 10? 50 g / l, preferably 10? The end point of the electrowinning is controlled to 20 g / l. While the tin electrolysis is continued, the tin concentration in the liquid gradually decreases. The electrolytic treatment is stopped before the Sn concentration is lower than 10 g / l, preferably 30 g / l, and the liquid is sent to the neutralization process after electrolysis.

In the neutralization step, it is managed so that the redox potential (ORP) of the liquid after electrolysis does not become below a fixed value. That is, it is common that the ORP value in the electrolyte is oxidized by electrolysis and the ORP value is -200 mV (vs Al / AgCl) or more, but in some cases, the ORP value is less than -200 mV. In this case, since the removal efficiency of As at the time of neutralization deteriorates, it is preferable to set it as -200 mV or more, Preferably it is -200 mV or more and -100 mV or less for the reason of chemical cost. In this case, hydrogen peroxide as an oxidant is added to increase the ORP value to -200 mV or more.

Thereafter, an acid such as sulfuric acid, hydrochloric acid or nitric acid, preferably sulfuric acid is added to lower the pH, whereby a Sn neutralized product is obtained. The Sn neutralized product is its shape is not clear, the Sn compound, the hydroxide _{(Sn (OH) 4),} Na 2 (Sn (OH) 6), Na 2 SnO 3 of which is or in the form of a plurality of the Sn compound in such It is thought that Sn can be recovered. This Sn neutralized material is solid-liquid separated and collect | recovered. If the pH is too high, Sn neutralization will not be produced. If the pH is too low, the removal efficiency of As deteriorates. It is preferable to set it as 10.

Table 1 shows changes in tin and arsenic concentrations before and after representative neutralization.

2 shows the concentration of As and Sn when the pH was lowered from pH = 13.5, and FIG. 3 shows the remaining ratio of As and Sn when the pH was lowered from pH = 13.5 . According to FIGS. 2 and 3, the pH is 9? When it is about 10, it can be seen that tin easily precipitates preferentially while at least a part of arsenic remains in the solution. From this, pH = 9? It is understood that adjustment to 10 is preferable.

After neutralization, the liquid can be sent to a wastewater treatment step, and deasphishing can be performed by a conventional method.

Sn neutralized materials can be added to the electrolytic extracting liquid to increase the recovery rate of tin. As an aspect of the said injection, when Sn concentration of electrolytic collection falls, you may throw in, For example, the concentration of Sn is 20? It can adjust to 40 g / L and can collect tin as electrodeposition tin by electrolytic collection.

Electrodeposited tin collect | recovered by using this invention can be made into high quality of 99.5 mass% or more. As an example, Table 2 shows the data obtained by actual operation.

Example

Examples of the present invention are described below, but the examples are not intended to limit the invention for the purpose of illustration.

(Example 1) (When the initial Sn concentration of the electrolytic sampling liquid is high as 30-50 g / ℓ)

The scum was obtained by processing soda. The scum contained about 20 mass% of Sn, about 4 mass% of As, about 30 mass% of lead, about 6 mass% of copper, and about 5 mass% of antimony. The scum was leached with a liquid (pH: 13.5) in which caustic soda was dissolved in hot water at 70 ° C. so as to have a slurry concentration of 300 g / L, and Pb and Sb were dropped as a residue. In the leachate, Sn ： 30? 50 g / l was dissolved. Pb and Cu were dropped as sulfides by adding sodium sulfide to this solution and sulfiding.

The obtained sulfided liquid was used as an electrolytic sampling liquid (initial Sn: 30-50 g / L). The Sn electrodeposition metal was collect | recovered by electrolytically collecting this at current density: 75 A / m <2> and liquid temperature: 70 degreeC. The concentration of Sn in the liquid at the end point of the electrolytic sampling is 10? It was managed to be 15 g / l. The concentration of Sn in the electrolytic sample liquid at the end point is 10? By managing at 15 g / L, the direct rate of Sn can be raised.

As a result of continuing electrolytic collection of tin under the above operating conditions, about 80% of the amount of Sn dissolved in the solution by scum leaching was recovered as an electrodeposition metal by electrolytic collection. There was no generation of arsine gas. The remaining 20% is Sn concentration 10? Since it contained 15 g / L, it sent to the neutralization process. The ORP value of the solution is oxidized to -200 mV or higher (vs Al / AgCl, hereinafter) by electrolytic sampling, but sometimes lower than -200 mV. In this case, hydrogen peroxide was added to adjust the ORP value to -200 mV, and then sent to the neutralization step.

In the neutralization step, after the electrolysis, the liquid was brought to pH = 9 with sulfuric acid, and Sn was recovered as a neutralized form. Even in the neutralization step, no generation of arsine gas was observed.

Table 3 shows changes in tin and arsenic concentrations before and after representative neutralization.

Drainage (liquid after neutralization) was sent to the wastewater treatment process, and deasphishing was performed.

Sn neutralization was used to maintain Sn concentration at 10 g / l or more by injecting when the Sn concentration of the electrolytic sample was lowered, and thereafter, tin was recovered as electrodeposited tin by electrolytic collection.

The quality of the obtained electrodeposition tin was a value of 99.5 mass% or more, as shown in Table 4. Moreover, electrolytic collection was possible in the safe environment which does not generate arsine gas.

(Comparative Example 1) (Electrochemical Sampling When Initial Tin Concentration of Electrolyte Sampling Solution is Low (9 g / L))

In contrast to the above, with electrolytic extract liquid having a tin concentration of 9 g / L, arsine gas was generated when electrodeposited tin under the same conditions as in Example 1, resulting in a dangerous state.

Example 2 (Sn concentration is maintained at 30 to 50 g / l when Sn concentration of the electrolytic sample is lowered.)

The concentration of Sn in the liquid at the end point of electrolytic collection is 30? Except having managed to be 50 g / L, Sn was electrolytically collected on the conditions similar to Example 1. Sn concentration in the electrolytic sample liquid at the end point is 30? By managing at 50 g / L, the current efficiency of Sn electrolysis collection can be improved.

As a result of continuously performing electrolytic collection of tin under the above operating conditions, the current efficiency of Sn electrolytic collection was able to maintain 90% or more. There was no generation of arsine gas. The liquid after electrolysis whose Sn concentration is 30 g / L or less was sent to the neutralization process. In the same manner as in Example 1, the ORP value of the solution is oxidized to -200 mV or more by electrolysis, but may be lower than -200 mV. In this case, hydrogen peroxide was added to adjust the ORP value to -200 mV, and then sent to the neutralization step.

In the neutralization step, after the electrolysis, the liquid was brought to pH = 9 with sulfuric acid, and Sn was recovered as a neutralized form. Even in the neutralization step, no generation of arsine gas was observed.

Table 5 shows changes in tin and arsenic concentrations before and after the typical neutralization.

Drainage (liquid after neutralization) was sent to the wastewater treatment process, and deasphishing was performed.

Sn neutralized materials are added when the concentration of Sn in the electrolytic sample is lowered to increase the concentration of Sn by 30? It was used to raise it to 50 g / L or more, and tin was collect | recovered as electrodeposition tin after that by electrolytic collection. As a result, the current efficiency could be increased to 94%. In the same manner as in Example 1, electrolytic collection could be performed in a safe environment without generating arsine gas.

(Example 3) (Electrolytic sampling in case of low initial tin concentration (15 g / L) of electrolytic solution)

Unlike the above, the electrolytic extracting liquid having an initial tin concentration of 15 g / l in the electrolytic extracting liquid, which is safe under the same conditions as in Example 1, does not generate arsine gas when the tin is electrodeposited. Electrolytic collection was possible in the environment. Moreover, current efficiency was 70%.

In addition, the present invention includes the following aspects.

(1) an electrolytic collection step of performing electrolytic collection of tin while maintaining the Sn concentration in the tin electrolytic sampling liquid containing at least arsenic at 10 g / l or more,

For the liquid after electrolysis obtained in the above process, the ORP value is maintained at -200 mV (vs AgCl / Ag) or higher, or when the ORP value is lower than -200 mV, an oxidizing agent is added to adjust at -200 mV or higher. And a neutralization step of changing the tin into the form of Sn neutralized material while dissolving at least a part of arsenic in the liquid after the electrolysis by lowering the pH.

(2) The electrolytic picking method of tin according to (1), which maintains the Sn concentration in the tin electrolytic picking solution at 30 g / l or more.

(3) In (1) or (2), pH is set to 9? Electrolytic sampling method of tin adjusted to 10.

(4) (1) The electrolytic picking method of tin according to any one of (3), wherein the oxidizing agent is hydrogen peroxide.

(5) (1) The electrolytic picking method of tin according to any one of (4), further comprising a step of separating the arsenic content and solid-liquid separated from the Sn neutralized material obtained in the step in a solution.

(6) (1) The method for electrolytic picking up tin according to any one of (4), wherein the Sn neutralized material is redissolved in the solution of electrolytic picking and the tin is recovered as electrodeposited tin by electrowinning.

(7) (1) The tin electrolytic extracting liquid according to any one of (6) is a liquid after sulfidation obtained through a step of leaching with a caustic soda solution to a soda scum obtained by soda treatment of coarse liquor, followed by a step of sulfiding a liquid after leaching. Electrolytic Sampling Method of Tin.

Claims (6)

A method for recovering tin from an arsenic-containing solution, wherein the tin electrolytic sampling liquid containing at least arsenic is electrolytically treated under conditions in which hydrogen is not generated. The method of claim 1,
And wherein said electrolytic treatment is carried out at a tin concentration of at least 10 g / l. The method according to claim 1 or 2,
The electrolytic treatment is stopped at a tin concentration of 10 g / l or more, and for the liquid after electrolysis obtained by the electrolytic treatment, the ORP value is maintained at -200 mV (vs AgCl / Ag) or higher, or the ORP value is-. If it is lower than 200 mV, after the oxidizing agent is added and adjusted to -200 mV or more, the pH is lowered to change tin in the form of Sn (OH) ₄ while dissolving at least part of arsenic in the liquid after electrolysis. How to include. The method of claim 3, wherein
The method further comprises solid-liquid separation of the Sn neutralized material, dissolving the Sn neutralized material again in the solution of electrolytic collection, and recovering tin by electrolytic treatment. The method according to claim 1 or 2,
The tin electrolytic extraction liquid is electrosorption of tin, which is a liquid after sulfidation, obtained through a step of leaching a caustic soda solution to a soda scum obtained by soda treatment of crude lead, followed by a step of sulfiding a liquid after leaching. Way. The method of claim 3, wherein
Oxidizing agent is hydrogen peroxide.

Images