JP2001172731A - Method for recovering bismuth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently separating and recovering by separating bismuth from copper and lead produced from a non-ferrous smelting process with a wet-type treatment. SOLUTION: In the recovering method of the bismuth, bismuth salt water- solution is subjected to pH adjustment, and after precipitating crude oxy-bismuth chloride, the bismuth is separated and recovered from the copper and the lead by dissolving with acid and reducing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recovering valuable resources from an aqueous solution of a bismuth salt. More specifically, the present invention relates to a method of recovering bismuth, which is a valuable resource, by separating it from copper and lead by wet processing. It is about the method.

[0002]

2. Description of the Related Art Bismuth is contained in ores such as lead, copper, tin, silver, and gold, and is produced as a by-product of smelting nonferrous metals. Bismuth is often produced along with copper and lead ore, and remains in the crude metal by dry smelting. For example, bismuth remaining in the blister copper is concentrated in an electrolytic solution together with other impurities in a copper electrolytic refining process. On the other hand, most bismuth is volatilized by high heat in the dry process of copper smelting, and is collected as smoke ash in cotrel together with lead, arsenic, antimony and the like. These are further sent to a lead smelting process.

[0003] Bismuth concentrated in the copper electrolyte is removed by, for example, ion exchange resin or copper removal electrolysis, and most of the removed bismuth is repeated in a dry process.

[0004] The bismuth collected by volatilization with high heat together with lead is sent to a lead smelting process and subjected to a dry treatment in an electric furnace or the like.
Move into coarse lead. Crude lead is electrolytically purified in, for example, a hydrosilicofluoric acid bath, and lead is electrodeposited on a cathode, and bismuth becomes anode mud (anode slime). The anode mud is further subjected to a dry treatment to become coarse bismuth. This crude bismuth is electrorefined in, for example, a hydrosilicofluoric acid bath or a chloride bath to obtain a product bismuth.

[0005] In the recovery of the bismuth product, a dry treatment is performed in many cases as described above, and this dry treatment uses lead, which is not preferable in working environment. For this reason,
It is desired to develop a method for recovering bismuth without performing dry treatment. In addition, bismuth often behaves together with lead, copper, or arsenic or antimony, which is a homologous element, and separation from these components is also an issue.

[0006]

An object of the present invention is to provide a method for separating and recovering bismuth by a wet method, which solves the above problems.

[0007]

Means for Solving the Problems The present inventors have conducted various studies on a method for recovering bismuth from a raw material containing bismuth. As a result, (1) an aqueous solution of a bismuth salt was adjusted in pH. A method for recovering bismuth, comprising separating bismuth from copper, lead and the like by dissolving and reducing an acid after precipitating a bismuth salt, and collecting the bismuth. (2) The method according to (1), wherein the bismuth salt aqueous solution is an intermediate product in a non-ferrous smelting process. (3) The method according to (1), wherein the pH adjustment of the bismuth salt aqueous solution is 20 ° C. or more, the reaction end point pH is 0.5 to 2.0, and the treatment time is 1 hour or more. (4) The acid dissolution of the recovered bismuth is 20 ° C. or more and hydrochloric acid 1
Mol / L or more, treatment time 1 hour or more, pulp concentration 100
g / L or more, the method according to (1), wherein (5) The method according to (1), wherein the reduction of the acid-dissolved bismuth is carried out at a temperature of 20 ° C. or higher using a metal that is electrochemically lower than bismuth. (6) The reduction of bismuth has an oxidation-reduction potential of 100 mV (A
g / AgCl) or more, and the bismuth concentration in the liquid at this time is 0.5 g / L or more. (7) The crude bismuth sponge obtained by reduction is dissolved. The method according to (1), wherein the anode can be used for bismuth electrolysis by casting. I found

The structure of the present invention will be described below in detail. Although the configuration has been described using an example, the present invention is not limited to this example.

[0008] Bismuth is contained in ores such as lead, copper, tin, silver and gold, and is produced as a smelting by-product of these metals. Bismuth is often produced along with copper or lead ore, and remains in the crude metal due to smelting.
For example, bismuth remaining in the blister copper is concentrated in an electrolytic solution together with other impurities in a copper electrolytic refining process. On the other hand, most bismuth is volatilized by high heat in the dry process of copper smelting and is collected as smoke ash together with lead, arsenic, antimony and the like in a cotrel or the like, and these are further sent to the lead smelting process.

Bismuth concentrated in the copper electrolyte is removed by, for example, an ion exchange resin or copper removal electrolysis, and most of the removed bismuth is repeated in the smelting process.

The bismuth collected by volatilization with high heat together with the lead is sent to a lead smelting process and subjected to a dry treatment in an electric furnace or the like.
Move into coarse lead. Crude lead is electrolytically purified in, for example, a hydrosilicofluoric acid bath, and lead is electrodeposited on a cathode, and bismuth becomes anode mud (anode slime). The anode mud is further subjected to a dry treatment to obtain crude bismuth. This crude bismuth is electrorefined in a hydrosilicofluoric acid bath or a chloride bath to become a product bismuth.

The present inventors have conducted various studies on the recovery of bismuth. As a result, the pH of an aqueous solution of bismuth salt was adjusted to precipitate the bismuth salt, followed by dissolving and reducing the acid to obtain bismuth, copper, lead, etc. And that it can be separated.

As an intermediate of the non-ferrous smelting process containing bismuth, for example, there is an aqueous solution of bismuth salt which is acidic to hydrochloric acid obtained by subjecting smoke ash to various wet treatments. As the pH of the bismuth salt aqueous solution is increased, bismuth is hydrolyzed and precipitates as bismuth oxychloride. At this time, the liquid temperature for pH adjustment was 6
It has been found that increasing the temperature to about 0 ° C. lowers the hydrolysis pH of bismuth. At this time, since arsenic and copper do not precipitate, it is possible to separate bismuth from arsenic and copper.

As a method for raising the pH, for example, addition of an alkali agent typified by caustic soda, dilution with water, addition of an intermediate treatment of bismuth salt, and the like can be mentioned.

When the liquid temperature is low, no decrease in the pH of the bismuth hydrolysis is observed, and it is difficult to separate bismuth from arsenic or copper. As shown in Table 1, the liquid temperature is preferably 20 ° C or higher, more preferably 55 to 65 ° C. When the liquid temperature is higher than 65 ° C., heat energy is lost, which is not preferable.

[Table 1]

The processing time is preferably at least 1 hour as shown in Table 2, more preferably at least 4 hours. If the treatment time is short, the rate of sediment transfer other than bismuth increases.

[Table 2]

As shown in Table 3, the end point pH is 0.5 to
2.0 is preferable, and more preferably, pH 0.8-1.
2 is preferred. When the pH is lower than 0.8, the transfer rate of bismuth precipitation is low, and when the pH is higher than 1.2, impurities such as Pb are mixed into the precipitate.

[Table 3]

The precipitate obtained by adjusting the pH is bismuth oxychloride containing bismuth as a main component, and the recovered bismuth is dissolved in an acid such as hydrochloric acid.

As shown in Table 4, the hydrochloric acid concentration is preferably at least 1 mol / L, more preferably at least 2 mol / L. When the concentration of hydrochloric acid is low, bismuth is dissolved, but the concentration of bismuth in the solution cannot be increased, and the amount of bismuth dissolved becomes large.

[Table 4]

The acid dissolution of the recovered bismuth may be at least 20 ° C. When the liquid temperature is raised to a high temperature, the dissolution rate is improved, but the liquid is rapidly dissolved even at room temperature.

As shown in Table 5, the dissolution time of the recovered bismuth is preferably 1 hour or more, more preferably 4 hours or more. If the dissolution time is shorter than 1 hour, the entire amount of bismuth will not be dissolved, and if the dissolution time exceeds 4 hours, improvement in dissolution efficiency cannot be expected.

[Table 5]

The pulp concentration was 100 g as shown in Table 6.
/ L or more is preferred. If the pulp concentration is lower than 100 g / L, there is a margin in the solubility of bismuth and the pulp concentration is 200 g / L.
If it is higher than g / L, undissolved components are generated due to the solubility of bismuth. However, the undissolved portion does not pose a major problem because the undissolved portion can be repeated for the acid treatment.

[Table 6]

Bismuth dissolved in hydrochloric acid is reduced by a reducing agent. As the reducing agent, one which is electrochemically lower than bismuth can be used. For example, aluminum, lead, iron and the like can be mentioned. When bismuth is reduced using iron as a reducing agent, the reduction reaction proceeds rapidly.

The liquid temperature is preferably 20 ° C. or higher. As the liquid temperature increases, the reaction rate of bismuth reduction tends to increase. However, since the reaction rate is relatively high even at room temperature, increasing the liquid temperature has little merit.

The reduction potential is 100 mV (Ag / AgCl,
It is preferable to keep the temperature at (normal temperature) or higher. At a potential lower than this, the potential sharply decreases, that is, the bismuth concentration sharply decreases, so that it is difficult to control the reaction by the oxidation-reduction potential. At a high potential, a large amount of bismuth still remains in the liquid, so there is little merit in terms of bismuth recovery. The bismuth concentration at this reduction potential is 0.5 g / L or more.

Table 7 shows the crude bismuth quality obtained by the reduction. The conventional method refers to a known dry processing method.

[0026]

[Table 7]

According to the present invention, it was possible to obtain a coarse bismuth sponge equivalent to the bismuth anode according to the conventional method.
Thus, the bismuth sponge obtained by the present invention can be used as a bismuth electrolytic anode by a known method by melting and casting.

As described above, a simple method for separating bismuth from copper or lead and recovering bismuth has been established.

【Example】

Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the embodiments.

As an intermediate product obtained by subjecting smoke ash in the copper smelting process to various wet treatments, there is an aqueous bismuth hydrochloride acid solution. The composition of this liquid is as shown in Table 8.

[0031]

[Table 8]

200 g / L of NaOH was added as a pH adjuster to 10 L of an aqueous bismuth solution at 60 ° C. to adjust the pH to 1.
The mixture was left stirring for hr. This slurry was filtered and subjected to solid-liquid separation to obtain 60 g of a bismuth recovered material having the components shown in Table 9.

[0033]

[Table 9]

26 g of the obtained bismuth recovery product was cooled to room temperature at room temperature.
It was repulped to 0.2 L of a mol / L hydrochloric acid solution. Table 10 shows the analysis values of the solution after dissolution of hydrochloric acid. After 4 hours of repulping, solid-liquid separation by filtration was performed. At this time, little residue was generated.

[0035]

[Table 10]

An iron plate (surface area: 0.00575 m 2) was charged as a reducing agent into 0.2 L of the hydrochloric acid solution, and the mixture was stirred at room temperature for reduction. ORP potential (Ag / AgCl) 280
Stop the reduction at mV, immediately perform solid-liquid separation by filtration,
11 g of a reduced recovered product was obtained.

Table 11 shows the analysis values of the reduced recovered product and the liquid after reduction.

[Table 11]

[0038]

As described above, according to the present invention, bismuth which is a valuable resource can be separated from copper and lead and recovered by wet processing.

[Brief description of the drawings]

FIG. 1 shows one embodiment of a processing flow of the present invention.

Claims (7)

[Claims] 1. A method for recovering bismuth, comprising: adjusting the pH of an aqueous solution of bismuth salt to precipitate the bismuth salt; dissolving and reducing the acid to separate and recover bismuth from copper, lead, and the like. 2. The method according to claim 1, wherein the bismuth salt aqueous solution is an intermediate product in a non-ferrous smelting process. 3. The method according to claim 1, wherein the pH adjustment of the bismuth salt aqueous solution is 20 ° C. or more, the reaction end point pH is 0.5 to 2.0, and the treatment time is 1 hour or more. 4. The method according to claim 1, wherein the bismuth recovered product is dissolved in an acid at 20 ° C.
The method according to claim 1, wherein the hydrochloric acid is 1 mol / L or more, the treatment time is 1 hour or more, and the pulp concentration is 100 g / L or more. 5. The method according to claim 1, wherein the reduction of the acid-dissolved bismuth is carried out at a temperature of 20 ° C. or higher with a metal which is electrochemically lower than bismuth. 6. The reduction of bismuth at an oxidation-reduction potential of 100 m
2. The method according to claim 1, wherein the concentration of bismuth in the liquid is 0.5 g / L or more at V (Ag / AgCl) or more. 7. The method according to claim 1, wherein the crude bismuth sponge obtained by reduction can be used as an anode for bismuth electrolysis by melt casting.