JP2019147990A - Method of recovering ruthenium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for selectively recovering ruthenium from an acidic liquid of hydrochloric acid containing at least one of arsenic and antimony. A method for recovering ruthenium, which comprises depositing ruthenium by contacting metallic copper with an acidic solution of hydrochloric acid containing ruthenium and at least one of arsenic and antimony, wherein the acidic solution of hydrochloric acid has a liquid temperature of 50 to 85°C. A method for recovering ruthenium, which comprises contacting the metallic copper in a state. [Selection diagram] Figure 1

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. 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. Further, there is a problem that ruthenium mixed as an impurity increases in the platinum, palladium recovery process, or selenium recovery process due to an increase in the ruthenium concentration.

  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.

  Furthermore, some raw materials may contain arsenic or antimony harmful substances as impurities. In particular, when liquids leached with non-ferrous metal electrolytic starch are included, various toxic substances are included, so the techniques such as simply introducing base metals or electrowinning may generate highly toxic arsine gas or hydrogen antimonide. Concerned. In addition, the ruthenium solution is strongly acidic. Under the condition that hydrogen is generated from the base metal by the mineral acid, there is a risk of explosion, which is not preferable.

  Arsenic and antimony are not preferably mixed in the ruthenium purification process. The chemical behavior of these elements varies depending on the valence, and the separation is complicated. It is preferable to precipitate only ruthenium while leaving these elements in 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. 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 present inventors have found that ruthenium can be recovered by cementing a hydrochloric acid acidic solution containing at least one of arsenic or antimony with metallic 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 brought into contact with an acidic hydrochloric acid solution containing ruthenium and at least one of arsenic or antimony to deposit ruthenium, wherein the hydrochloric acid acidic solution has a liquid temperature of 50 to 85 ° C. The method for recovering ruthenium, comprising bringing the metal copper into contact.
(2) The metallic 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 ruthenium recovery method according to (2), wherein the hydrochloric acid acidic solution is controlled to 65 ° C. or higher while air is blown as an oxidizing agent in 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, and the hydrochloric acid acidic solution is controlled at 60 ° C. to 75 ° C. (2) or (3 The method for recovering ruthenium as described in 1).
(5) The method for recovering ruthenium according to any one of (1) to (4), wherein the acidic hydrochloric acid solution is a copper electrolytic starch solution, 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 or more that of ruthenium (1) to (5) ) The ruthenium recovery method according to any one of the above.

  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 a time-dependent change of a ruthenium density | concentration. It is a figure which shows a time-dependent change of an arsenic density | concentration. It is a figure which shows the time-dependent change of antimony concentration. It is a figure which shows the time-dependent change of the ruthenium density | concentration at the time of cementation enforcement in each liquid temperature. It is a figure which shows a time-dependent change of the arsenic density | concentration at the time of cementation enforcement in each liquid temperature. It is a figure which shows the time-dependent change of the antimony density | concentration 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 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.

  In addition, when sulfuric acid ions are present, even if the acid is hydrochloric acid, there is a concern about the dissolution of copper as in the case of sulfuric acid. If the temperature is adjusted, the consumption of metallic copper can be suppressed.

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

  The recovered ruthenium is metal ruthenium and can be processed by the existing ruthenium purification process. In general, the cementation is excessively added in cementation, but unreacted copper dissolves when heated by adding an oxidizing agent under acidic conditions of hydrochloric acid.

  When single metal copper is used, arsenic and antimony react with copper in a chloride bath to form copper arsenide and copper antimonide. From the viewpoint of further concentrating ruthenium in the ruthenium precipitate, it is preferable to remove copper arsenide and copper antimonide by oxidation treatment.

  The oxidation treatment can be carried out by maintaining the temperature above a certain level for a while and re-dissolving the precipitate without solid-liquid separation immediately after cementation. If the temperature is 60 ° C. or higher, redissolve. At this time, aeration (blowing air) or iron (III) salt addition can be performed. If copper arsenide or copper antimonide is removed after solid-liquid separation, aeration or an appropriate oxidizing agent may be added again in an acidic solution to maintain a certain temperature for a while. The aeration is performed by controlling the hydrochloric acid acidic solution to 65 ° C. or higher while blowing air as an oxidizing agent. Instead of aeration or in addition to aeration, Fe (III) may be added as an oxidizing agent, and the hydrochloric acid acidic solution may be controlled at 60 ° C to 75 ° C. The amount of Fe (III) added is preferably 5 mol times or less, more preferably 3 mol times or less of the total amount of arsenic and antimony.

  In the case of cementation with copper, the amount of copper used can be suppressed by previously removing metals, selenium, and tellurium that react with copper with a reducing agent. As the reducing agent, inexpensive sulfur dioxide 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.

  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.
300 ml of the liquid after selenium separation 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 (manufactured by Wako Pure Chemical Industries, Ltd., grade 1) was added and stirred while aeration. The reaction was completed in 120 minutes.
For comparison, a system that does not aerate (copper powder only), a system that does not aerate and adds 6 g of iron (III) chloride hexahydrate (iron chloride) after 60 minutes, 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 collected and adjusted to 50 ml. The concentrations of ruthenium, arsenic and antimony in the solution were quantified by ICP-OES (SEPS Instruments SPS3100). The reduced amount of water was replenished with pure water. The tracer which corrects the fall of the liquid quantity was not attached. That is, it is an actual solution concentration, and the concentration is inevitably lowered by the decrease in sampling. The results are shown in FIGS.

  It can be seen that ruthenium in the solution is efficiently reduced by adding copper powder. 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 began to rise over time and were redissolved.

  Aeration promotes redissolution of arsenic and antimony. When Fe (III) is further added, re-dissolution occurs rapidly. However, in any oxidizing agent, a part of Ru is redissolved. In particular, when Fe (III) is added, the concentration of Ru in the liquid suddenly increases after a certain point in time, and the addition amount is determined by the amounts of arsenic and antimony, so be careful not to add it excessively. Cost. 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-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. Next, 1.5 g of copper powder was added and stirred. Two levels of the system heated to 80-85 ° C. were performed, while one was aerated.
Test samples were taken every 20 minutes. 2 ml of the sample solution was collected and adjusted to 50 ml. The concentrations of ruthenium and arsenic were 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 FIGS.

  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 rapidly occurred, and the ruthenium concentration finally decreased to 20 mg / L or lower.

  Arsenic was greatly reduced in concentration at 65 ° C. or higher after adding 1.5 g of copper powder. It is presumed that copper arsenide was formed. It is considered that almost no copper arsenide is formed in a system heated at 50 to 55 ° C. (a decrease in concentration is an influence of sampling).

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

  Antimony behaves similarly to arsenic. Even when copper antimonide is produced, if heating is continued at 65 ° C. or higher, mixing into ruthenium that has cemented and precipitated can be suppressed.

Claims (6)

  A method for recovering ruthenium by depositing ruthenium by bringing metallic copper into contact with an acidic hydrochloric acid solution containing at least one of ruthenium and arsenic or antimony, wherein the metal is added to the acidic hydrochloric acid solution at a liquid temperature of 50 to 85 ° C. A method for recovering ruthenium, comprising contacting copper.   The oxidant is supplied to the hydrochloric acid acidic solution at a liquid temperature of 60 ° C or higher after contacting the metallic copper with the hydrochloric acid acidic solution at a liquid temperature of 50 to 85 ° C. The method for recovering ruthenium as described.   The method for recovering ruthenium according to claim 2, wherein the hydrochloric acid acidic solution is controlled to 65 ° C or higher while air is blown as an oxidizing agent in supplying the oxidizing agent to the hydrochloric acid acidic solution.   4. The ruthenium according to claim 2, wherein Fe (III) is added as an oxidizing agent when the oxidizing agent is supplied to the hydrochloric acid acidic solution, and the hydrochloric acid acidic solution is controlled at 60 ° C. to 75 ° C. 5. Recovery method.   The method for recovering ruthenium according to claim 1, wherein the acidic hydrochloric acid solution is a copper electrolytic starch solution, 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 size 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.

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