JP6994983B2 - How to recover ruthenium - Google Patents

Description

The present invention relates to a method for recovering ruthenium from an acidic hydrochloric acid solution containing ruthenium and at least one of arsenic or antimony. It is particularly effective when applied to the slime treatment process generated in the electrolytic refining process of copper smelting.

In the copper dry smelting, copper concentrate is melted to obtain 99% or more blister copper in a converter and a purification furnace, and then electrolytic copper having a purity of 99.99% or more is produced in an electrolytic refining step. In recent years, metal scraps containing precious metals derived from electronic parts have been introduced as recycling raw materials in converters, and valuable resources other than copper precipitate as slime during electrolytic refining.

Precious metals, rare metals, and selenium and tellurium contained in copper concentrate are also concentrated in this slime at the same time. These elements are individually separated and recovered as copper smelting by-products.

A wet smelting method is often applied to the treatment of this slime. For example, Patent Document 1 discloses a method in which silver is recovered from slime by hydrochloric acid-hydrogen peroxide, the dissolved gold is recovered by solvent extraction, and then other valuable resources are sequentially reduced and recovered by sulfur dioxide. Patent Document 2 discloses a method in which gold and silver are recovered by the same method, valuable resources are reduced and precipitated with sulfur dioxide, and only selenium is distilled and removed to concentrate precious metals.

The solution after recovering the noble metal contains rare metal ions, tellurium, and selenium, and it is necessary to recover these valuable resources. As a recovery method, a method of recovering the precipitate generated by the reducing agent and a method of mixing the solution with the copper concentrate, drying it with a dryer, and repeating it in a smelting furnace are known.

In particular, the method of recovering the precipitate generated by sulfur dioxide, which is shown in Patent Document 1, has many advantages in terms of cost and production scale. In addition, since each element is sequentially precipitated, it is also effective for separation and purification.

In the method of recovering valuable resources using sulfur dioxide, the valuable resources can be sequentially reduced and recovered after dissolution. First, platinum and palladium precipitate. Selenium is then reduced. Iridium, ruthenium, and rhodium have relatively low redox potentials and are difficult to be reduced, and remain in the solution until the end. Generally, ruthenium in a solution is recovered as ruthenium dioxide by distillation after oxidation with a strong oxidizing agent such as bromic acid.

Japanese Unexamined Patent Publication No. 2001-316735 Japanese Unexamined Patent Publication No. 2004-190134

As an oxidizing agent used when distilling ruthenium, for example, bromic acid can be considered, but its price is high. Further, ruthenium contained in the solution derived from the smelting starch process is usually about 100 to 300 mg / L, and the oxidation efficiency is low because it reacts with other coexisting substances.

Ruthenium oxide that is distilled is also known to be a toxic compound. Multi-stage distillation is not preferable because it handles toxic substances at a high concentration and poses a safety problem. Further, if impurities are mixed during distillation, a purification operation is required again, but azeotropic fraction is likely to be mixed in distillation. Therefore, it is necessary to increase the purity of crude ruthenium for distillation.

In order to increase the purity of crude ruthenium, it is necessary to roughly separate and concentrate ruthenium in a harmless form. In the concentration, the solution is reduced to recover ruthenium and other elements as a precipitate. As other elements, selenium, tellurium, and rhodium are common.

When sulfur dioxide is used as a reducing agent during crude separation, the final recovery rate of ruthenium is 30 to 50%. Unrecovered ruthenium can be precipitated with a strong reducing agent such as hydrazine and repeated in the copper starch treatment step. Alternatively, it is distributed in the sludge and discarded in the wastewater treatment process. Yields of these methods are by no means good.

When unprecipitated ruthenium is repeated in the copper starch treatment step, the ruthenium concentration gradually increases. Further, an increase in the ruthenium concentration causes a problem that ruthenium mixed as an impurity in the platinum or palladium recovery step or the selenium recovery step increases.

As mentioned above, in the recovery of ruthenium, it is once concentrated as a mixture of various elements. The residue after elution of chalcogen from this concentrate becomes a ruthenium raw material and is put into the ruthenium purification step. However, a practical method for efficiently precipitating ruthenium from an acidic hydrochloric acid solution to concentrate and recover it is not known.

A method for cementing ruthenium as an impurity in an iridium solution with copper is described in, for example, Japanese Patent Application Laid-Open No. 2004-190058. However, copper cementation of ruthenium is only theoretically possible, and when the target liquid contains selenous acid or tellurous acid, ruthenium can be recovered due to the coating effect and reactivity during cementation. Is uncertain. In fact, ruthenium is known to have multiple oxidation states, and there is no guarantee that cementation will proceed because the coordination form and redox potential differ depending on the valence.

For example, when comparing standard redox potentials in various forms,
[Ru (NH ₃ ) ₆ ] ³⁺ + e → [Ru (NH ₃ ) ₆ ] ²⁺ 0.20V
Ru ³⁺ + e → Ru ²⁺ 0.29V
Ru ²⁺ + 2e → Ru 0.46V
RuCl ₃ + 3e → Ru 0.68V
Ru ⁴⁺ + e → Ru ³⁺ 0.87V
[Ru (NH ₃ ) ₆ ] ³⁺ + 3e → Ru 0.89V (Revised 3 Chemistry Handbook Basic Edition II Quoted from the Chemical Society of Japan)
It can be seen that the redox potential changes significantly depending on the number and type of ligands. In addition, the potential does not determine the reaction rate, and whether or not cementation as an industrial process is actually possible depends on the conditions.

Furthermore, depending on the raw material, arsenic and antimony harmful substances may be contained as impurities. In particular, when targeting a liquid in which an electrolytic starch of a non-ferrous metal is leached, various toxic substances are contained, so a method such as simply adding a base metal or electrowinning may generate highly toxic arsin gas or antimonated hydrogen. I am concerned. In addition, the ruthenium solution is strongly acidic. Under the condition that hydrogen is generated by mineral acid as a base metal, there is a risk of explosion, which is not preferable.

In addition, it is not preferable to mix arsenic and antimony in the ruthenium purification process. The chemical behavior of these elements differs depending on the change in valence, and their separation is complicated. It is preferable to precipitate only ruthenium while leaving these elements in the solution.

In view of such conventional circumstances, the present invention provides a method for selectively recovering ruthenium from an acidic hydrochloric acid solution containing at least one of arsenic or antimony. In particular, a liquid in which an electrolytic starch generated in an electrolytic refining process in copper smelting is dissolved is a good target.

As a result of diligent research to solve the above problems, the present inventors have found that an acidic hydrochloric acid solution containing at least one of arsenic or antimony can be cemented with metallic copper to recover ruthenium. The present invention has been completed based on such findings.

That is, the present invention includes the following inventions.
(1) A method for recovering ruthenium in which metallic copper is brought into contact with an acidic hydrochloric acid solution containing ruthenium and at least one of arsenic or antimony to precipitate ruthenium, and the liquid temperature is 50 to 85 ° C. in the acidic hydrochloric acid solution. A method for recovering ruthenium, which comprises contacting the metallic copper with the metal.
(2) The metal copper is brought into contact with the hydrochloric acid acidic liquid at a liquid temperature of 50 to 85 ° C., and then an oxidizing agent is supplied to the hydrochloric acid acidic liquid at a liquid temperature of 60 ° C. or higher (. The method for recovering ruthenium according to 1).
(3) The method for recovering ruthenium according to (2), wherein the hydrochloric acid acidic solution is controlled to 65 ° C. or higher while blowing air as an oxidizing agent when supplying the oxidizing agent to the hydrochloric acid acidic solution.
(4) When supplying an oxidizing agent to the hydrochloric acid acidic solution, Fe (III) is added as an oxidizing agent to control the hydrochloric acid acidic solution to 60 ° C. to 75 ° C. (2) or (3). ) Is the method for recovering ruthenium.
(5) The method for recovering ruthenium according to any one of (1) to (4), wherein the hydrochloric acid acidic solution is a solution of copper electrolytic starch and the hydrochloric acid concentration is 2 mol / L or more.
(6) The metallic copper is added to the hydrochloric acid acidic solution as copper powder having an average particle size of 1 mm or less, and the amount of the metallic copper added is 10 times by weight or more that of ruthenium (1) to (5). ). The ruthenium recovery method according to any one of.

According to the present invention, ruthenium can be selectively recovered from an acidic hydrochloric acid solution containing at least one of arsenic or antimony.

It is a figure which shows the time-dependent change of a ruthenium concentration. It is a figure which shows the time-dependent change of the arsenic concentration. It is a figure which shows the time-dependent change of the antimony concentration. It is a figure which shows the time-dependent change of the ruthenium concentration at the time of performing cementation at each liquid temperature. It is a figure which shows the time-dependent change of the arsenic concentration at the time of performing cementation at each liquid temperature. It is a figure which shows the time-dependent change of the antimony concentration at the time of performing cementation at each liquid temperature.

Platinum group elements, heavy metals, and toxic elements are concentrated in the electrolytic starch produced in the electrolytic refining process of non-ferrous metal smelting, especially copper smelting. Platinum group elements and toxic elements are not smelted alone and are either recovered as by-products of other metals or separated from recycled materials such as waste catalysts. Therefore, this method can also be applied to recycling from waste.

Hydrochloric acid and hydrogen can be added to dissolve the electrolytic starch, but silver forms an insoluble silver chloride precipitate with chloride ions immediately after dissolution. If it is a solution containing an oxidizing agent and chlorine, for example, aqua regia or chlorine water, the precious metals can be dissolved and silver can be separated as silver chloride. Since it is a chloride bath, platinum group elements, rare metal elements, selenium, and tellurium are distributed in the leachate noble liquid (PLS).

The leachate noble liquid (PLS) is cooled once to precipitate and separate chlorides of base metals such as lead and antimony. The gold is then separated into organic phases by solvent extraction. Dibutyl carbitol (DBC) is widely used as a gold extractant.

Valuables can be precipitated and recovered by reducing PLS after extracting gold, but the order of precipitation is naturally determined because the redox potential differs depending on the element. First, gold, platinum, palladium, then chalcogens such as selenium and tellurium, and then inert noble metals such as ruthenium and iridium are precipitated.

Reducing sulfur is used as the reducing agent in terms of price and efficiency, and sulfur dioxide is most suitable because it can be supplied in large quantities and at low cost by roasting linz-Donaw gas or sulfide ore. The reduction rate of inert precious metals is extremely slow with sulfur dioxide and sulfites. In the first place, the content is not high, for example, ruthenium in the copper electrolytic starch solution is about 150 to 300 mg / L. At present, the recovery rate of ruthenium by sulfur dioxide is about 30 to 50% in a reaction time of 6 to 8 hours, but it is expected that 10 hours or more is required if the ruthenium is completely precipitated. This is too long and not a realistic reaction time.

Therefore, metal cementation is the most efficient way to recover ruthenium more efficiently. It is known that ruthenium is reduced to metallic ruthenium by metals that generate hydrogen with acids such as zinc, magnesium, and aluminum.

As mentioned above, the standard electrode potential of the divalent ruthenium ion is 0.46V. The divalent copper ion is 0.34 V, and theoretically, of course, metallic copper causes the reduction of ruthenium. However, under acidic hydrochloric acid conditions, ruthenium is not reduced by the typical reducing agents sulfurous acid (standard electrode potential 0.17V) and formic acid (standard electrode potential -0.20V), or the reaction rate is extremely slow. In particular, this problem is remarkable when the hydrochloric acid concentration is 2 mol / L or more.

Similarly, the hexachloride complex of the iridium chloride complex is not cemented by copper even though the standard electrode potential is much higher at 0.86V. That is, the possibility of cementation of a transition metal element is not determined only by the redox potential.

The reason for this is unknown, but when ruthenium becomes a complex ion, it is possible that a strong coordinate bond is formed by backdonation to the ligand. For this reason, electron transfer in the inner category mechanism becomes difficult, and the reaction pathway that reduces by the outer category mechanism in which electrons move directly from the metal may work more effectively.

It is possible to precipitate ruthenium by cementation even with a metal that is lower than copper. However, since it is acidic with hydrochloric acid, reactions that generate hydrogen occur in parallel, increasing the amount of metal used for cementation and generating hydrogen that has a risk of explosion. Copper does not react with hydrochloric acid to produce hydrogen.

Therefore, the temperature of the hydrochloric acid acidic solution is adjusted to 50 to 85 ° C. when the metallic copper is brought into contact with the hydrochloric acid acidic solution. As described above, under acidic hydrochloric acid conditions, ruthenium does not undergo reduction even when it comes into contact with metallic copper, or the reaction rate is extremely slow, but the reaction rate increases when the temperature of the acidic hydrochloric acid solution is 50 ° C or higher. .. On the other hand, when the temperature of the acidic hydrochloric acid solution exceeds 85 ° C., the dissolved oxygen causes a dissolution reaction of metallic copper. The temperature of the acidic hydrochloric acid solution is preferably 60 to 85 ° C, more preferably 70 to 80 ° C.

In addition, when sulfuric acid ion is present, there is a concern that copper may be dissolved even in hydrochloric acid acidity as in sulfuric acid, but in the case of dilute sulfuric acid, the reaction between acid and copper is slow. By adjusting the temperature, it is possible to suppress the consumption of metallic copper.

In particular, when the copper electrolytic starch contains arsenic or antimony, the liquid hydrochloric acid acidic solution obtained by dissolving it with hydrochloric acid and an oxidizing agent also contains arsenic or antimony. The liquid after dissolution recovers antimony by cooling, but a part of it remains. When acid-dissolved arsenic and antimony are cemented with aluminum, iron, and zinc, there is a risk of generating toxic arsin gas and antimony hydrogen, respectively. With metallic copper, you don't have to worry about this.

The recovered ruthenium is metallic ruthenium and can be processed in the existing ruthenium purification process. Generally, in cementation, an excessive amount of a substituted metal is added, but unreacted copper is dissolved by adding an oxidizing agent and heating under acidic hydrochloric acid conditions.

When elemental copper is used, arsenic and antimony react with copper in the chloride bath to produce copper arsenide and copper antimony. From the viewpoint of further concentrating ruthenium in the ruthenium precipitate, it is preferable to remove copper arsenide and copper antimony by an oxidation treatment.

Oxidation treatment can be performed by redissolving the precipitate by maintaining a temperature above a certain level for a while without solid-liquid separation immediately after cementation. If the temperature is 60 ° C. or higher, it will be redissolved. At this time, aeration (blowing air) and iron (III) salt addition can be performed. If copper arsenide and copper antimony are removed after solid-liquid separation, aeration or an appropriate oxidizing agent may be added again in an acidic solution to maintain the temperature above a certain level for a while. Aeration is performed by controlling the hydrochloric acid acidic solution to 65 ° C. or higher while blowing air as an oxidizing agent. It is also possible to control the hydrochloric acid acidic solution to 60 ° C. to 75 ° C. by adding Fe (III) as an oxidizing agent instead of or in addition to aeration. The amount of Fe (III) added is preferably 5 mol times or less, more preferably 3 mol times or less, which is 5 mol times or less of the total amount of substances of arsenic and antimony.

In the case of copper cementation, the amount of copper used can be suppressed by removing metals, selenium and tellurium that react with copper with a reducing agent in advance. Inexpensive sulfur dioxide is preferable as the reducing agent.

The shape of the metallic copper charged in the cementation may be a plate shape, a rod shape, a shot or a copper powder. Instead of a tank-type reaction tank, copper may be charged into a packed bed or a circulation tank to allow the liquid to be treated to pass through. The contact method is determined by the allowable amount of copper content in the recovered material, reaction efficiency, and equipment restrictions. Higher grades of metallic copper used for cementation are preferred, but alloys with iron and zinc should be avoided. Relatively high-purity copper such as waste electric wires, poorly-appearing electrolytic copper, and recast copper anodes are used. Of course, copper having a large specific surface area such as copper powder is more preferable.

When copper is charged into the tank type reaction tank, it is preferable to charge copper powder. Copper powder generally refers to copper particles having an average particle size of 1 mm or less. The amount to be added is preferably 10 times by weight or more with respect to ruthenium. When chalcogens coexist in the solution, it is preferable to add more copper powder.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited thereto.

(Experimental Example 1)
Copper was removed from the electrolytic starch recovered from the copper electrolytic refining process of copper smelting with sulfuric acid. Concentrated hydrochloric acid and 60% hydrogen peroxide solution were added and dissolved, and solid-liquid separation was performed to obtain PLS (leached noble liquid). The PLS was cooled to 6 ° C. to remove the base metal by precipitation. The acid concentration was adjusted to 2N or more, and DBC (dibutylcarbitol) and PLS were mixed to extract gold. The PLS after gold extraction was heated to 70 ° C., and a mixed gas of sulfur dioxide and air (sulfur dioxide concentration 5 to 20%) was blown into the PLS to reduce the precious metal and selenium and separate them into solid and liquid.
After separating the selenium, 300 ml of the liquid was weighed, heated to 80 to 85 ° C., and stirred while blowing a mixed gas of air and sulfur dioxide. After 15 minutes, the supply of mixed gas of air and sulfur dioxide was stopped. 1.5 g of copper powder (1st grade manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred while aeration. The reaction was completed in 120 minutes.
For comparison, a system without aeration (copper powder only), a system with 6 g of iron (III) chloride hexahydrate added after 60 minutes without aeration (iron chloride), and a mixed gas of air and sulfur dioxide without adding copper powder. The blowing system (SO ₂ gas only) was tested.
Test samples were taken every 20 minutes. 2 ml of the sample solution was separated and adjusted to 50 ml. The concentrations of ruthenium, arsenic and antimony in the solution were quantified by ICP-OES (SPS3100 manufactured by Seiko Instruments Inc.). The reduced water content was replenished with pure water. No tracer was attached to compensate for the decrease in liquid volume. That is, it is the actual solution concentration, and the concentration inevitably decreases as it decreases by sampling. The results are shown in FIGS. 1 to 3.

It can be seen that the addition of copper powder efficiently reduces ruthenium in the solution. At the same time, it is clear that the concentrations of arsenic and antimony also decreased. However, it can be seen that the concentrations of arsenic and antimony started to increase with the passage of time and were redissolved.

Aeration promotes the redissolution of arsenic and antimony. Further, when Fe (III) is also added, redissolution occurs rapidly. However, a part of Ru is redissolved in any of the oxidizing agents. In particular, when Fe (III) is added, the concentration of Ru in the liquid rises sharply after a certain point in time, and it should be noted that the amount of addition is determined by the amount of arsenic and antimony and is excessively added. It takes. Alternatively, the reaction rate is controlled by adjusting the temperature of the solution to 60 ° C to 75 ° C.

(Experimental Example 2)
The same selenium separation solution as in Experimental Example 1 was blown with a mixed gas of sulfur dioxide and air for 15 minutes to adjust the tellurium concentration to 200 mg / L or less. Weighing 300 ml, each solution was heated to 50-55 ° C, 65-70 ° C, and 80-85 ° C. Then, 1.5 g of copper powder was added and stirred. Two levels of the system heated to 80-85 ° C. were carried out, and one was aerated.
Test samples were taken every 20 minutes. 2 ml of the sample solution was separated and adjusted to 50 ml. The concentrations of ruthenium and arsenic were quantified by ICP-OES (SPS3100 manufactured by Seiko Instruments Inc.). The reduced water content was replenished with pure water. No correction was made using the tracer. 0 minutes was the time when the blowing of sulfur dioxide was started. The results are shown in FIGS. 4 to 6.

Copper cementation of ruthenium was possible above 50 ° C. The higher the temperature, the more efficient the reaction, and the reaction was rapid above 65 ° C., and the ruthenium concentration finally dropped to 20 mg / L or less.

After adding 1.5 g of copper powder, the concentration of arsenic was greatly reduced at 65 ° C. or higher. It is presumed that the cause was the formation of copper arsenide. It is considered that copper arsenide is hardly formed in a system heated at 50 to 55 ° C. (decrease in concentration is due to sampling).

When the reaction was continued, copper arsenide was gradually dissolved and the arsenic concentration increased again. If the heating is continued at 70 ° C. or higher even after the ruthenium is deposited, the mixing of copper arsenide with ruthenium can be suppressed. It is still more efficient to blow in air.

Antimony behaves similarly to arsenic. Even when antimonyated copper is generated, if heating is continued at 65 ° C. or higher, it is possible to suppress the contamination of the precipitated ruthenium by cementation.

Claims (5)

A method for recovering ruthenium in which metallic copper is brought into contact with an acidic hydrochloric acid solution containing ruthenium and at least one of arsenic or antimony to precipitate ruthenium. The metal is prepared in the acidic hydrochloric acid solution at a liquid temperature of 50 to 85 ° C. A method for recovering ruthenium, which comprises contacting copper and then supplying an oxidizing agent to the hydrochloric acid acidic liquid at a liquid temperature of 60 ° C. or higher . The method for recovering ruthenium according to claim 1 , wherein when supplying the oxidizing agent to the hydrochloric acid acidic solution, the hydrochloric acid acidic solution is controlled to 65 ° C. or higher while blowing air as an oxidizing agent. The ruthenium according to claim 1 or 2 , wherein Fe (III) is added as an oxidizing agent to control the hydrochloric acid acidic solution to 60 ° C. to 75 ° C. when supplying the oxidizing agent to the hydrochloric acid acidic solution. How to collect. The method for recovering ruthenium according to any one of claims 1 to 3 , wherein the hydrochloric acid acidic solution is a solution of copper electrolytic starch and the hydrochloric acid concentration is 2 mol / L or more. The metal copper is added to the hydrochloric acid acidic solution as a copper powder having an average particle size of 1 mm or less, and the amount of the metallic copper added is 10 times by weight or more that of ruthenium, according to any one of claims 1 to 4 . The described method for recovering ruthenium.

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