JP6708065B2 - Tellurium separation and recovery method - Google Patents

Description

The present invention relates to a tellurium separation and recovery method capable of recovering tellurium contained in a metal smelting residue in a high yield.

Tellurium, which is a type of rare metal, is used as a material for solar cells and some electronic components, and an alloy of bismuth and tellurium is also used as a thermoelectric conversion element. On the other hand, tellurium is highly ubiquitous and is produced by recovering from the residue produced during the metal smelting process.

For example, as a by-product of electrolytic refining of copper, copper telluride is produced in many copper smelters around the world and used as a raw material for refined tellurium. Further, recently, in addition to copper telluride, a reducing slag containing tellurium and selenium as main components is produced as a by-product as a by-product of the wet precious metal recovery step and is used as a raw material for purified tellurium.

For example, Patent Document 1 discloses that tellurium containing tellurium is leached with an alkali and then neutralized to precipitate tellurium dioxide, the precipitate is recovered and further leached with alkali, and tellurium is recovered from the leached solution by electrolytic separation. A treatment method is disclosed.
Further, in Patent Document 2, a tellurium-containing raw material is mixed with hydrochloric acid, and tellurium is oxidatively leached in the presence of an oxidizing agent. Disclosed is a method of separating and recovering tellurium by precipitating chloride and separating the precipitate to recover tellurium.

Japanese Patent No. 3616314 Japanese Patent No. 58403069

However, in the tellurium treatment method disclosed in Patent Document 1, when copper telluride is oxidatively leached with a caustic soda solution, copper occupying about half of the raw material becomes copper hydroxide and covers the surface of the copper telluride. Therefore, there is a problem that the dissolution of tellurium is hindered and a part of the tellurium remains undissolved and cannot be recovered.
Further, in the method of separating and recovering tellurium disclosed in Patent Document 2, it is difficult to separate and recover tellurium in a high yield because the pH of precipitation is close to that of ruthenium or rhodium contained in many metal smelting residues. there were.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tellurium separation and recovery method capable of recovering tellurium in a high yield with a simple process.

In order to solve the above problems, a method for separating and recovering tellurium of the embodiment is an oxidation roasting of a first residue containing tellurium, selenium, and a platinum group element, which is obtained after recovering gold and silver from a metal smelting residue. Then, a selenium recovery step of separating and recovering selenium, and a second residue obtained after recovering selenium from the first residue in the selenium recovery step are dissolved in an alkaline liquid, and most of tellurium is leached and recovered. Alkali leaching step, and the third residue obtained after leaching and recovering most of the tellurium from the second residue in the alkali leaching step is mixed with hydrochloric acid containing an oxidizing agent to remove the balance of tellurium and platinum group elements. In order to promote the hydrochloric acid oxidation step of obtaining a mixed liquid containing the mixture liquid and the formation of a chloride complex of a platinum group element contained in the mixed liquid, the liquid temperature of the mixed liquid is 75° C. or higher and 90° C. or lower for at least 30 minutes A complex formation step of holding the above, and a neutralization separation step of neutralizing the hydrochloric acid oxidation leachate separated from the mixed solution that has undergone the complex formation step to separate the balance of tellurium and the platinum group element from each other, Characterize.

According to the method for separating and recovering tellurium of the present invention, the residue containing tellurium and the platinum group element is mixed with the hydrochloric acid oxidizing solution and held at a high temperature to accelerate the formation of the chloride complex of the platinum group element. be able to.

Then, by using the hydrochloric acid oxidation leaching solution in which the platinum group element is sufficiently converted to the chloride complex, and by adjusting the pH to a predetermined value, only tellurium is selectively precipitated, and the chloride complex of the platinum group element remains dissolved. Can be Therefore, it becomes possible to reliably separate and recover tellurium and platinum group elements from each other in a simple process.

The complex formation step is a step in which the liquid temperature of the mixed liquid after being heated by the reaction heat in the hydrochloric acid oxidation step is set to 75° C. or higher and 90° C. or lower, and held for 30 minutes or longer and 240 minutes or shorter. It is characterized by
When the liquid temperature of the mixed liquid is less than 75° C., complex formation is insufficient, and when the liquid temperature exceeds 90° C., evaporation of the mixed liquid is severe and an excessive local exhaust device or the like is required. If the holding time is less than 30 minutes, the complex formation is insufficient, and if it exceeds 240 minutes, the complex formation does not proceed any further.

The neutralization separation step is characterized in that the hydrochloric acid oxidation leachate is neutralized to a pH of 1.0 or higher and a pH of 3.0 or lower to separate the balance of tellurium and the platinum group element from each other.

According to the method for separating and recovering tellurium of the present invention, it is possible to provide a method for separating and recovering tellurium that is capable of recovering tellurium in a high yield in a simple process.

4 is a flow chart showing the method of separating and recovering tellurium of the present invention step by step. It is a graph which shows the result of an Example.

Hereinafter, the method for separating and recovering tellurium of the present invention will be described with reference to the drawings. The following embodiments are specifically described in order to better understand the gist of the invention, and do not limit the invention unless otherwise specified. Further, in the drawings used in the following description, in order to facilitate understanding of the features of the present invention, for convenience, there are cases where essential parts are enlarged, and the dimensional ratios of the respective constituent elements are the same as in reality. Not necessarily.

FIG. 1 is a flowchart showing the tellurium separation and recovery method of the embodiment step by step.
When tellurium is recovered by the method for separating and recovering tellurium of the present invention, first, as a metal smelting residue, for example, a slime-like copper smelting residue generated by electrolytic refining of copper is prepared.

First, gold and silver are recovered using the copper smelting residue (gold and silver recovery step S1).
In the gold and silver recovery step S1, for example, a copper smelting residue is mixed with a hydrochloric acid oxidizing solution in which an oxidizing agent is mixed with hydrochloric acid, and gold and silver are eluted in the leachate. Then, gold and silver are separated and recovered from the leachate by neutralization such as pH adjustment.

On the other hand, selenium is then separated and recovered from the residue (first residue) remaining in the gold and silver recovery step S1 (selenium recovery step S2). The first residue contains tellurium, selenium, and platinum group elements.

In the selenium recovery step S2, for example, the first residue left in the gold and silver recovery step S1 is roasted in an oxidizing atmosphere, and selenium contained in the first residue is volatilized as an oxide to be separated and recovered. When the first residue contains an excessive amount of water, it is preferable to carry out drying or calcination in advance before the selenium recovery step S2. In the selenium recovery step S2, roasting is performed at a roasting temperature of, for example, 300° C. or higher and 600° C. or lower using a roasting furnace. Examples of the roasting furnace include a rotary roasting furnace and a multi-stage floor roasting furnace.

Next, a part of tellurium oxide is separated and recovered from the roasting residue (second residue) remaining in this selenium recovery step S2 (alkali leaching step S3). The second residue contains tellurium and platinum group elements.

In the alkali leaching step S3, for example, the second residue is mixed with an alkaline solution such as an aqueous sodium hydroxide solution, and tellurium oxidized in the previous step is eluted into the leaching solution. Most of the tellurium that has undergone the roasting process is tellurium oxide, and since tellurium oxide is soluble in the alkaline liquid, most of the tellurium is transferred to the leachate. As a result, in the alkali leaching step S3, most of the tellurium is dissolved in the leachate and the undissolved tellurium remains.

Next, hydrochloric acid oxidation leaching is performed using the residue (third residue) remaining in the alkali leaching step S3 (hydrochloric acid oxidation step S4). The third residue contains the balance of tellurium and platinum group elements that have not been transferred to the leachate in the alkali leaching step S3.

In the hydrochloric acid oxidation step S4, the third residue is mixed with a hydrochloric acid oxidizing solution prepared by mixing an oxidizing agent with hydrochloric acid, and tellurium and platinum group elements are eluted into the leachate. The hydrochloric acid used in the hydrochloric acid oxidizing solution preferably has an initial concentration of about 4 mol/L to 6 mol/L. Hydrogen peroxide (H ₂ O ₂ ) or sodium chlorate (NaClO ₃ ) can be used as the oxidizing agent. The addition amount of the oxidizing agent is preferably in a range where the redox potential (ORP) is 800 to 900 mV (Ag/AgCl electrode reference). If the ORP is less than 800 mV, the oxidative leaching of tellurium is not sufficient, and if it is higher than 900 mV, the consumption of the oxidizing agent increases.

By mixing the third residue with the hydrochloric acid oxidizing solution and heating the hydrochloric acid oxidizing solution, the solution temperature is brought to 75°C to 90°C.

Next, the hydrochloric acid oxidizing solution is mixed with the third residue to obtain a high temperature mixed solution, which is kept warm for a predetermined time so that the solution temperature does not decrease (complex forming step S5). The liquid temperature of the mixed liquid is, for example, in the temperature range of 75° C. or higher and lower than the boiling point. It is preferably 75° C. or higher and 90° C. or lower. If the predetermined temperature cannot be reached by merely increasing the liquid temperature by mixing the third residue with the hydrochloric acid oxidizing liquid, the mixed liquid is further heated to a temperature range of 75° C. or higher and 90° C. or lower.

Then, the mixed liquid in such a temperature range is held for at least 30 minutes or longer, for example, for 30 minutes to 240 minutes. The temperature of the mixed solution may be maintained by continuously heating the mixed solution, or by covering the container containing the mixed solution with a heat insulating member to prevent the temperature from decreasing.
Further, it is preferable to stir the mixed liquid while maintaining the mixed liquid at a high temperature. For example, the mixed liquid is stirred at about 200 to 400 rpm.

In the complex formation step, if an autoclave is used and the pressure is increased, the liquid temperature of the mixed liquid can be 100° C. or higher. As a result, the holding time can be further shortened. In this case, the holding time can be set to 30 minutes or less.

When the remainder of tellurium and the third residue containing the platinum group element are mixed with the hydrochloric acid oxidizing solution and kept at the high temperature for about 30 minutes to 240 minutes, the formation of the platinum group chloride complex is promoted. . For example, ruthenium and rhodium contained in the copper smelting residue as platinum group elements are converted into ruthenium chloride complex and rhodium chloride complex, respectively. The higher the liquid temperature and the longer the reaction time, the more such a platinum group element chloride complex is produced. In the complex forming step S5, more platinum group elements are converted to chloride complexes, as compared with the case where the third residue is mixed with a hydrochloric acid oxidizing solution in which hydrochloric acid is mixed with an oxidizing agent and allowed to cool as it is.

Next, the residue and the hydrochloric acid oxidation leachate are separated from the mixed solution that has undergone the complex formation step S5. This hydrochloric acid oxidation leachate contains tellurium and a chloride complex of a platinum group element. Next, using this hydrochloric acid oxidation leaching solution, tellurium contained in the solution and the chloride complex of the platinum group element are separated from each other (neutralization separation step S6).

In this neutralization separation step S6, for example, the hydrochloric acid oxidation leachate is adjusted to pH 1. As a result, most of the tellurium contained in the hydrochloric acid-oxidized leachate, for example, about 90%, is precipitated as tellurium oxychloride. On the other hand, the precipitation rate of the platinum group element, for example, ruthenium chloride complex is 20% or less, the precipitation rate of the rhodium chloride complex is 0.1% or less, and most of the platinum group element chloride complex is hydrochloric acid oxidation leachate. It remains dissolved in.

After that, if the precipitate and the hydrochloric acid oxidation leaching solution are filtered off, almost all of the remaining tellurium that could not be recovered in the alkali leaching step S3 can be selectively recovered.

On the other hand, as a reference, when the hydrochloric acid oxidation leachate in a state in which the chloride complex of the platinum group element is not sufficiently generated without the complex formation step S5 is adjusted to pH 1 in the neutralization separation step, 47% of ruthenium and 32% of rhodium are obtained. Precipitates and becomes difficult to separate from tellurium.

When recovering the metal tellurium from the filtered precipitate of tellurium oxychloride, for example, the tellurium oxychloride precipitate is dissolved in an alkali to separate the residue, and a sulfidizing agent is added to the alkali solution to add a sulfur in the liquid. Impurity metals are precipitated and separated (sulfurized purification solution treatment), and the purified solution treated alkaline solution is made strongly acidic and a reducing agent is added, and tellurium in the solution is reduced and precipitated at an oxidation-reduction potential of less than 350 mV to produce metal tellurium. Can be recovered.

As described above, according to the method for separating and recovering tellurium of the present invention, the residue containing tellurium and the platinum group element is mixed with the hydrochloric acid oxidizing solution, and for example, at a high temperature of 75° C. or higher and 90° C. or lower for at least 30 minutes. The formation of the chloride complex of the platinum group element can be promoted only by holding the above. Then, by using the hydrochloric acid oxidation leachate in which the platinum group element is sufficiently converted to a chloride complex, and by adjusting the pH to a predetermined value, only tellurium is selectively precipitated, while the platinum group element chloride complex is dissolved. Can be Therefore, it becomes possible to reliably separate and recover tellurium and platinum group elements from each other in a simple process.

Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The embodiments and their modifications are included in the scope of the invention and the scope thereof, and are included in the invention described in the claims and the scope of equivalents thereof.

As a sample, a smelting residue containing tellurium (Te), ruthenium (Ru), and rhodium (Rh) was prepared. Using this smelting residue, samples of the following Examples 1 and 2 and Comparative Example 1 were prepared.
(Example 1) The smelting residue was subjected to a hydrochloric acid oxidation step at a liquid temperature of 75°C, held at that temperature for 240 minutes while stirring at 300 rpm, and then left to cool to room temperature to obtain the sample liquid of Example 1. Obtained. Hydrogen peroxide solution was used as an oxidizing agent, and was added until the redox potential of the solution reached 850 mV (Ag/AgCl electrode standard). The free chlorine concentration in this stock solution was 5 M/L, Te: 14.3 g/L, Ru: 0.483 g/L, and Rh: 0.0941 g/L.
(Example 2) The smelting residue was subjected to a hydrochloric acid oxidation step at a liquid temperature of 75° C., the liquid temperature was raised to 90° C., and the mixture was stirred at 300 rpm for 120 minutes and then left to cool to room temperature. The sample liquid of Example 2 was obtained. Hydrogen peroxide solution was used as an oxidizing agent, and was added until the redox potential of the solution reached 850 mV (Ag/AgCl electrode standard). The free chlorine concentration in this stock solution was 5 M/L, Te: 13.6 g/L, Ru: 0.478 g/L, Rh: 0.0975 g/L.
(Comparative Example 1) Hydrochloric acid oxidation step was carried out on the smelting residue at a liquid temperature of 75°C, and then rapidly cooled to room temperature to obtain a sample liquid of Comparative Example. Hydrogen peroxide solution was used as an oxidizing agent, and was added until the redox potential of the solution reached 850 mV (Ag/AgCl electrode standard). The free chlorine concentration in this stock solution was 5 M/L, Te: 12.9 g/L, Ru: 0.427 g/L, and Rh: 0.0806 g/L.

When 25% or 1 mol/L caustic soda solution was added to the sample solutions of Examples 1 and 2 and Comparative Example 1 to adjust the pH, precipitation occurred and a slurry was formed. The slurry was sampled for each predetermined pH, and the precipitate and the filtrate were separated with a quantitative filter paper. The concentration of each element in the sample liquid before filtration and the filtrate was measured by the ICP method, and the amount of each liquid was measured. The precipitation rate is, for example, in the case of element A, (precipitation rate (%))={(W _i −W)/W _i }×100 (W _i : the amount of A in the sample solution before filtration, W: filtrate) The quantity of A in the above).
With respect to Examples 1 and 2 and Comparative Example, Table 1 shows the precipitation rates of the respective elements in the pH range of -1.0 to 3.0. The change in precipitation rate with pH is shown in FIG.

According to FIG. 2 and Table 1, the precipitation rate at pH 1.0 was Te: 85%, Ru: 41%, Rh: 16% in Example 1, and Te: 86%, Ru: 29% in Example 2. Rh: 0.0%, whereas in Comparative Example 1, Te: 90%, Ru: 47%, Rh: 32%, and in Example 1 and Example 2, Ru and Rh , Te was confirmed to be well separated.

Claims (3)

A selenium recovery step of oxidizing and roasting the first residue containing tellurium, selenium and a platinum group element, which is obtained after recovering gold and silver from the metal smelting residue, and separating and recovering selenium,
An alkaline leaching step of dissolving the second residue obtained after recovering selenium from the first residue in the selenium recovering step in an alkaline solution, and leaching and recovering most of tellurium,
The third residue obtained after leaching and recovering most of the tellurium from the second residue in the alkali leaching step is mixed with hydrochloric acid containing an oxidizing agent to obtain a mixed solution containing the balance of tellurium and a platinum group element. Hydrochloric acid oxidation step,
A complex formation step of maintaining the liquid temperature of the mixed liquid at 75° C. or higher and 90° C. or lower for at least 30 minutes or more in order to promote the formation of a chloride complex of a platinum group element contained in the mixed liquid;
The complexation step to neutralize the amount released hydrochloric acid oxidation leachate from a mixture which has undergone, tellurium, characterized in that it comprises a neutralizing separation step of separating from each other the balance and platinum group elements tellurium, the separation and recovery Method. The complex formation step is a step in which the liquid temperature of the mixed liquid after being heated by the reaction heat in the hydrochloric acid oxidation step is set to 75° C. or higher and 90° C. or lower, and held for 30 minutes or longer and 240 minutes or shorter. The method for separating and recovering tellurium according to claim 1, wherein. The neutralization separation step neutralizes the hydrochloric acid oxidation leachate to pH 1.0 or more and pH 3.0 or less to separate the balance of tellurium and the platinum group element from each other. Tellurium separation and recovery method.

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