JP2019147991A - Method of recovering ruthenium - Google Patents

Abstract

Provided is a method for efficiently recovering ruthenium from an acidic hydrochloric acid solution containing ruthenium and at least one of selenium or tellurium.
A method for recovering ruthenium in which ruthenium is brought into contact with an acidic hydrochloric acid solution containing at least one of ruthenium and selenium or tellurium to precipitate ruthenium, wherein the total concentration of selenium and tellurium is 1 g / L. A method for recovering ruthenium, comprising: adjusting to the following, and bringing the metallic copper into contact with the acidic hydrochloric acid solution at a liquid temperature of 50 to 85 ° C.
[Selection] Figure 1

Description

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

  In copper dry smelting, copper concentrate is melted and converted to 99% or more of crude copper in a converter and refining furnace, and then, for example, electrolytic copper having a purity of 99.99% or more is produced in the electrolytic purification process. In recent years, scrap metal containing precious metals derived from electronic components has been introduced as recycling materials in converters, and valuable materials other than copper are precipitated as slime during electrolytic refining.

  Slime and tellurium contained in precious metals, rare metals, and copper concentrate are also concentrated in this slime. These elements are separated and recovered separately as byproducts of copper smelting.

  A hydrometallurgical process is often applied to the treatment of this slime. For example, Patent Document 1 discloses a method in which silver is recovered with hydrochloric acid-hydrogen peroxide and slime is recovered by solvent extraction, and then other valuable materials are sequentially reduced and recovered with sulfur dioxide. Patent Document 2 discloses a method of concentrating noble metals by recovering gold and silver by the same method, reducing and precipitating valuables with sulfur dioxide, and distilling and removing only selenium.

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

  In particular, the method for recovering a precipitate produced by sulfur dioxide, as disclosed in Patent Document 1, has many advantages in terms of cost and production scale. In addition, since each element precipitates sequentially, it is effective for separation and purification.

  In the method of recovering valuable materials using sulfur dioxide, valuable materials can be sequentially reduced and recovered after dissolution. First, platinum and palladium are precipitated. Next, selenium undergoes reduction. Iridium, ruthenium, and rhodium have a relatively low redox potential and are not susceptible to reduction, and remain in solution until the end. The ruthenium in the solution is generally recovered by ruthenium dioxide by distillation after oxidation with a strong oxidizing agent such as bromic acid.

JP 2001-316735 A JP 2004-190134 A

  For example, bromic acid can be considered as an oxidizing agent used when distilling ruthenium, but its price is high. Moreover, 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 due to the reaction with other coexisting substances.

  Further, it is known that ruthenium oxide to be distilled is a toxic compound. Multi-stage distillation is not preferred because the poison is handled at a high concentration and there is a safety problem. Furthermore, if impurities are mixed during distillation, a refining operation is required again, but distillation tends to mix azeotropic fractions. Therefore, it is necessary to increase the purity of the crude ruthenium for use in distillation.

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

  And when making sulfur dioxide precipitate as a reducing agent at the time of rough 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. Or it distributes in sludge at a wastewater treatment process, and is discarded. These methods cannot be said to have a good yield.

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

  As described above, in the recovery of ruthenium, it is once concentrated as a mixture of various elements. The residue after elution of the chalcogen component from this concentrate becomes the ruthenium raw material and is put into the ruthenium purification process. However, there is no known practical method for efficiently precipitating ruthenium from an acidic hydrochloric acid solution and concentrating / recovering it.

  A method for cementing ruthenium as an impurity of an iridium solution with copper is described in, for example, Japanese Patent Application Laid-Open No. 2004-190058. However, the cementation of ruthenium with copper is only theoretically possible, and if the target solution contains selenous acid or tellurite, the recovery of ruthenium due to the coating effect and reactivity during cementation. Is not certain. In fact, ruthenium is known to have a plurality of oxidation states. Coordination forms and oxidation-reduction potentials differ depending on the valence, and there is no guarantee that cementation will proceed.

For example, when comparing the standard redox potential 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 Fundamentals II, quoted from the Chemical Society of Japan)
It can be seen that the oxidation-reduction potential varies greatly depending on the number and type of ligands. Further, the potential does not determine the reaction rate, and whether or not the actual cementation is possible depends on conditions.

  Moreover, in the hydrochloric acid acidic solution containing selenium or tellurium as in this system, copper reacts with selenious acid or telluric acid to produce copper selenide, copper telluride, simple selenium, simple tellurium. If chalcogens are mixed in large quantities, they cannot be used for ruthenium distillation.

  In view of such a conventional situation, the present invention provides a method for efficiently recovering ruthenium from an acidic hydrochloric acid solution containing ruthenium and at least one of selenium or tellurium. The liquid which melt | dissolved the electrolytic starch generated especially in the electrolytic refining process in copper smelting is a good target.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have adjusted the total concentration of selenium and tellurium to a certain level or less in a hydrochloric acid solution containing ruthenium and at least one of selenium or tellurium. It was found that ruthenium can be recovered by contacting copper. 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 ruthenium is precipitated by bringing metallic copper into contact with an acidic hydrochloric acid solution containing at least one of ruthenium and selenium or tellurium, and the total concentration of selenium and tellurium is 1 g / L or less. And then the metal copper is brought into contact with the acidic hydrochloric acid solution at a liquid temperature of 50 to 85 ° C.
(2) The metallic copper is brought into contact with the hydrochloric acid acidic solution at a liquid temperature of 50 to 85 ° C., and then the precipitate containing ruthenium is recovered, and the precipitate is treated by alkali leaching ( The method for recovering ruthenium according to 1).
(3) The method for recovering ruthenium according to (1) or (2), wherein the total concentration of the selenium and tellurium is adjusted by adding sulfur dioxide or sulfite to the hydrochloric acid acidic solution. .
(4) The ruthenium recovery method according to any one of (1) to (3), wherein the selenium concentration is adjusted to 0.05 g / L or less.
(5) Before recovering the precipitate containing ruthenium, the metal copper is brought into contact with the hydrochloric acid acidic solution and then heated to 60 ° C. or more for 30 minutes or more. (1) to (4) The method for recovering ruthenium according to any one of the above.
(6) The precipitate containing ruthenium is recovered by solid-liquid separation, and then the precipitate is heated in an acidic solution for 30 minutes or more to 60 ° C. or more. A method for recovering ruthenium according to claim 1.
(7) The method for recovering ruthenium according to any one of (1) to (6), wherein the hydrochloric acid acidic solution is a copper electrolytic starch solution, and the hydrochloric acid concentration is 2 mol / L or more.
(8) The metal copper is added to the acidic hydrochloric acid solution as copper powder having an average particle size of 1 mm or less, and the amount of the metal copper added is 10 times or more by weight of ruthenium (1) to (7 ) The ruthenium recovery method according to any one of the above.
(9) The hydrochloric acid acidic solution and the metallic copper are contacted by continuously contacting the hydrochloric acid acidic solution with a tower containing the metallic copper, or the hydrochloric acid acidic solution continuously with the metal. The ruthenium recovery method according to any one of (1) to (8), which is performed in a tank reactor that is brought into contact with a tank containing copper.

  According to the present invention, ruthenium can be efficiently recovered from an acidic hydrochloric acid solution containing ruthenium and at least one of selenium or tellurium.

It is a figure which shows a time-dependent change of the density | concentration of ruthenium and copper. It is a figure which shows the time-dependent change of the concentration of tellurium and copper. It is a figure which shows the time-dependent change of the density | concentration of selenium and copper. It is a figure which shows the relationship between the total density | concentration of selenium and tellurium, and the density | concentration of ruthenium. It is a figure which shows the time-dependent change of the density | concentration of ruthenium at the time of cementation enforcement in each liquid temperature.

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

  Although hydrochloric acid and hydrogen peroxide can be added to dissolve the electrolytic starch, silver forms an insoluble silver chloride precipitate with chloride ions immediately after dissolution. In the case of a solution containing an oxidizing agent and chlorine, such as aqua regia or chlorine water, noble metals can be dissolved to separate silver as silver chloride. Since it is a chloride bath, platinum group elements, rare metal elements, selenium, and tellurium are distributed in the leached noble liquid (PLS).

  The leached noble liquid (PLS) is once cooled and precipitates and separates base metal chlorides such as lead and antimony. Thereafter, the gold is separated into an organic phase by solvent extraction. Dibutyl carbitol (DBC) is widely used as a gold extractant.

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

  As the reducing agent, reducing sulfur is used from the viewpoint of cost and efficiency. Among them, sulfur dioxide is optimal because it can be supplied in large quantities and at low cost by roasting converter gas or sulfide ore.

  Inert noble metals have a very slow reduction rate with sulfur dioxide or sulfite. In the first place, there is not much content, for example, ruthenium in a copper electrolytic starch solution is about 150 to 300 mg / L. The present ruthenium recovery rate 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 are required if it is completely precipitated. This is not a long and realistic reaction time.

  Therefore, metal-based cementation is the most efficient way to recover ruthenium more efficiently. It is known that ruthenium is reduced to metal ruthenium by a metal that generates hydrogen with an acid such as zinc, magnesium, and aluminum.

  As described 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, reduction of ruthenium occurs with metallic copper. However, under acidic conditions of hydrochloric acid, ruthenium is not subjected to reduction by a typical reducing agent such as sulfurous acid (standard electrode potential 0.17 V) or formic acid (standard electrode potential −0.20 V), or the reaction rate is extremely slow. This problem is particularly remarkable when the hydrochloric acid concentration is 2 mol / L or more.

  Similarly, the hexachloride complex of the iridium chloride complex does not undergo copper cementation even though the standard electrode potential is much higher at 0.86V. That is, the transition metal element does not necessarily determine whether or not cementation is possible only by the oxidation-reduction potential.

  The reason for this is unclear, but it is considered that when ruthenium becomes a complex ion, a strong coordinate bond is formed by back-donation to the ligand. For this reason, electron transfer in the inner sphere mechanism becomes difficult, and the reaction path of reduction by the outer sphere mechanism in which electrons move directly from the metal will work more effectively.

  It is possible to deposit ruthenium by cementation even in metals that are less basic than copper. However, because 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 may cause an explosion. If it is copper, it will not react with hydrochloric acid to produce hydrogen.

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

  When cementing with copper, the total concentration of selenium and tellurium needs to be adjusted to 1 g / L or less in advance. The reaction priority is selenium, tellurium and ruthenium. Therefore, if the total concentration of selenium and tellurium is not adjusted, the copper metal reacts with selenium and tellurium before reacting with ruthenium, increasing the amount of copper to be added. More preferably, the selenium concentration is 0.05 g / L or less and the tellurium concentration is 0.5 g / L or less. Since selenium is much more reactive with copper than ruthenium, adjusting the concentration of selenium is important. Some react with ruthenium even in the presence of tellurium. For adjusting the concentration of selenium and tellurium, sulfur dioxide, which is an inexpensive reducing agent, is preferable.

  The shape of the metal copper to be input by cementation may be a plate shape, a rod shape, a shot or copper powder. Instead of the tank-type reaction tank, copper may be charged into a packed tower or a circulation tank to allow the liquid to be treated to pass therethrough. The contact method is determined by the allowable amount of copper content in the recovered material, reaction efficiency, and restrictions on equipment. Higher grades of metallic copper used for cementation are preferred, but alloys with iron and zinc should be avoided. Copper of relatively high purity, such as waste electric wires, poor appearance copper, and copper anode reversal are used. Of course, copper having a large specific surface area such as copper powder is more preferable.

  When adding copper to the tank type reaction tank, it is preferable to add copper powder. Copper powder generally refers to copper particles having an average particle size of 1 mm or less. The input amount 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.

  The contact between the hydrochloric acid acidic liquid and the metallic copper is carried out by contacting the hydrochloric acid acidic liquid continuously with the tower containing the metallic copper, or the hydrochloric acid acidic liquid is continuously brought into contact with the tank containing the metallic copper. It can be carried out in a tank reactor.

When cementing with metallic copper, some copper reacts with selenious acid and tellurium (IV) chloride complexes to form insoluble Cu _n X-type salts. However, this salt is dissolved by acid treatment to become simple selenium or tellurium and copper ions. The final reaction is the same as when cemented.

The acid treatment is to heat a Cu ₂ X type salt at 60 ° C. or higher in an acidic solution. Cu ₂ X-type salts are susceptible to oxidation because they contain monovalent copper. The oxidation reaction is accelerated by heating. As a method of acid treatment, the slurry generated by cementation may be heated and stirred as it is, and a precipitate containing ruthenium may be heated in an acidic solution after solid-liquid separation. In any case, the acid treatment time is preferably 30 minutes or more from the viewpoint that copper is sufficiently converted to copper ions.

  It is necessary to remove impurities from the precipitated mixture and further increase the ruthenium concentration. Selenium and tellurium are known to dissolve in alkali. Conversely, ruthenium does not dissolve in alkali. Accordingly, when selenium and tellurium are removed by alkali leaching, it becomes possible to obtain crude ruthenium containing ruthenium and other metals.

  Crude ruthenium can be input into the ruthenium refining process. Crude ruthenium can be distilled and purified by acid dissolution and oxidation with bromic acid while containing other impurities such as rhodium and some iridium.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these.

(Experimental example 1)
Copper was removed from the electrolytic starch recovered from the copper electrorefining step of copper smelting with sulfuric acid. Concentrated hydrochloric acid and 60% aqueous hydrogen peroxide 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 (dibutyl carbitol) and PLS were mixed to extract gold. The PLS after the gold extraction was heated to 70 ° C., and a mixed gas of sulfur dioxide and air (sulfur dioxide concentration 5 to 20%) was blown to reduce the noble metal and selenium and to separate into solid and liquid.

  After separation of selenium, the liquid was heated to 80 ° C. and a mixed gas of sulfur dioxide and air was blown to precipitate a part of tellurium. After separating tellurium from solid and liquid, 200 ml was taken and heated to 80 to 83 ° C. The amount of water that decreased with time was replenished with pure water. Various reducing agents shown in Table 1 were added. All reagents were grade 1 or special grades manufactured by Wako Pure Chemical Industries. Every 1 hour, 2 ml of the sample solution was collected and adjusted to 50 ml. The concentration was quantified by ICP-OES (SEPS Instruments SPS3100). The results are shown in Table 1. In Table 1, when there is no reducing agent, the initial concentration is reflected. As shown in Table 1, the initial concentration of tellurium is 210 mg / L, and the initial concentration of selenium is 40 mg / L.

  It can be seen that the reaction is completed within 1 hour with copper powder and is particularly effective in removing ruthenium and tellurium. It can also be seen that the copper powder can leave most of the iridium in the liquid.

(Experimental example 2)
300 ml of the selenium-separated liquid obtained by the same operation as in Experimental Example 1 in another lot was weighed and stirred at 70 ° C. while blowing in sulfur dioxide. After 30 minutes, the supply of sulfur dioxide was stopped. 0.3 g or 0.9 g of copper powder (manufactured by Wako Pure Chemical Industries, Ltd., grade 1) was added and stirring was continued. The reaction was completed in 120 minutes.
For comparison, a system in which copper powder was not added and a system in which copper dioxide was added simultaneously with blowing in sulfur dioxide (added for 0 minute) were tested.
Test samples were taken every 20 minutes. 2 ml of the sample solution was collected and adjusted to 50 ml. The concentration was quantified by ICP-OES (SEPS Instruments SPS3100). The reduced amount of water was replenished with pure water. The concentrations of ruthenium, selenium and tellurium were corrected using arsenic (concentration 1.6 g / L) as a tracer. 0 minute was the time when the blowing of sulfur dioxide was started. The results are shown in FIGS. A broken line indicates a change in the concentration of copper in the solution. The legend indicates the amount of copper powder added. In the figure, 0 minutes means that copper powder was added simultaneously with blowing in sulfur dioxide.

  It can be seen that ruthenium in the solution is efficiently reduced by adding copper powder after reducing the selenium and tellurium concentrations with sulfur dioxide. Conversely, if the concentration is not adjusted with sulfur dioxide, the effect is low, and a large amount of copper must be added. It is clear that the concentration of copper increased and that ruthenium was cemented. FIG. 4 shows the relationship between the total concentration of selenium and tellurium and the concentration of ruthenium. When the total concentration of selenium and tellurium is 2.4 g / L or more, there is no change in the concentration of ruthenium. Since the effect is seen at 0.7 g / L, it is necessary to adjust the total concentration to 1 g / L or less in advance.

  It can be seen that selenium preferentially reacted when contacted with copper when a large amount of selenium was present. As can be seen from the system with 0.3 g added, tellurium reacts preferentially after the disappearance of selenium. However, in the system with 0.9 g added, ruthenium begins to decrease even when the remaining amount of tellurium is 600 mg / L, and only tellurium is preferentially reduced considering the difference in concentration of both elements. I understand that it is not.

  Even when the concentration of any element of selenium, tellurium or ruthenium decreased, the concentration of copper increased and it was clear that it was cemented with copper.

However, selenium and tellurium react with copper to form a Cu ₂ X type compound. At this time, copper is monovalent and is susceptible to oxidation in an acidic solution. When oxidized, it becomes Cu ²⁺ and selenium or tellurium alone, and has undergone copper cementation in the reaction mode.

(Experimental example 3)
The same selenium-separated 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. 300 ml was weighed and each solution was heated to 50 to 55 ° C, 65 to 70 ° C, and 80 to 85 ° C. Copper powder 1.5g was added and stirred.
Test samples were taken every 20 minutes. 2 ml of the sample solution was collected and adjusted to 50 ml. The concentration of ruthenium was quantified by ICP-OES (SEPS Instruments SPS3100). The reduced amount of water was replenished with pure water. Correction using a tracer was not performed. 0 minute was the time when the blowing of sulfur dioxide was started. The results are shown in FIG.

  The cementation of ruthenium with copper was possible above 50 ° C. The higher the temperature, the more efficient the reaction. At 65 ° C. or higher, the reaction was rapid, and ruthenium finally decreased to 20 mg / L or lower.

Claims (9)

  A method for recovering ruthenium in which metal copper is brought into contact with a hydrochloric acid acidic solution containing at least one of ruthenium and selenium or tellurium to precipitate ruthenium, wherein the total concentration of selenium and tellurium is adjusted to 1 g / L or less. Then, the metal copper is brought into contact with the acidic hydrochloric acid solution at a liquid temperature of 50 to 85 ° C.   2. The contact with the metallic copper at a liquid temperature of 50 to 85 [deg.] C. with the hydrochloric acid acidic solution, and then the precipitate containing ruthenium is recovered and the precipitate is treated by alkali leaching. The method for recovering ruthenium as described.   The method for recovering ruthenium according to claim 1 or 2, wherein the total concentration of selenium and tellurium is adjusted by adding sulfur dioxide or sulfite to the hydrochloric acid acidic solution.   The ruthenium recovery method according to any one of claims 1 to 3, wherein the selenium concentration is adjusted to 0.05 g / L or less.   Before recovering the deposit containing ruthenium, the metallic copper is brought into contact with the hydrochloric acid acidic solution and heated to 60 ° C or higher for 30 minutes or more. How to recover ruthenium.   The ruthenium according to any one of claims 1 to 4, wherein the precipitate containing ruthenium is recovered by solid-liquid separation, and then the precipitate is heated in an acidic solution for 30 minutes or more to 60 ° C or more. Recovery method.   The method for recovering ruthenium according to any one of claims 1 to 6, wherein the acidic hydrochloric acid 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 copper powder having an average particle diameter of 1 mm or less, and the amount of the metal copper added is 10 times or more by weight of ruthenium. The ruthenium recovery method described.   The contact between the hydrochloric acid acidic liquid and the metallic copper is a tower reactor in which the hydrochloric acid acidic liquid is continuously brought into contact with the tower containing the metallic copper, or the hydrochloric acid acidic liquid is continuously contained in the metallic copper. The method for recovering ruthenium according to any one of claims 1 to 8, wherein the method is carried out in a tank reactor in contact with the tank.