Method for recovering ruthenium

Abstract

To provide a method that enables efficient recovery of ruthenium.SOLUTION: A method for recovering ruthenium comprises the steps of: generating a ruthenium-containing gas from a solid or liquid containing ruthenium; and recovering ruthenium from the ruthenium-containing gas, wherein the step of recovering ruthenium includes a first aeration step in which the ruthenium-containing gas is passed through water or an acid, and, after the first aeration step, a second aeration step in which the ruthenium-containing gas is passed through hydrochloric acid to which a reducing agent has been added.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for recovering ruthenium. [Background technology]

[0002] A method using alkali fusion is known as a method for recovering ruthenium (Ru) from a ruthenium-containing mixture. For example, Patent Document 1 discloses a method for recovering ruthenium by alkali fusion of a ruthenium-containing mixture, leaching the molten residue with water, and adding a reducing agent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5376437 Summary of the Invention [Problem to be solved by the invention]

[0004] When a ruthenium-containing mixture contains antimony (Sb), lead (Pb), copper (Cu), etc., conventional methods such as those described in Patent Document 1 have the problem that it is difficult to concentrate ruthenium because a large amount of antimony, lead, and copper dissolves together with ruthenium during water leaching after alkali fusion.

[0005] An object of one embodiment of the present invention is to provide a method for efficiently recovering ruthenium. [Means for solving the problem]

[0006] a ruthenium-containing gas generation step of generating a ruthenium-containing gas containing ruthenium from a solid or liquid containing ruthenium; and recovering the ruthenium from the ruthenium-containing gas, The step of recovering ruthenium comprises: a first aeration step of aerating the ruthenium-containing gas through water or an acid solution; The method for recovering ruthenium comprises, after the first aeration step, a second aeration step of aerating the ruthenium-containing gas through hydrochloric acid to which a reducing agent has been added.

[0007] A second aspect of the present invention is In the method for recovering ruthenium according to the first aspect, the reducing agent is an alcohol or oxalic acid.

[0008] A third aspect of the present invention is The method further comprises a step of alkali-melting a ruthenium-containing mixture containing ruthenium, antimony, lead, copper, and arsenic to obtain an alkali-melt product, In the method for recovering ruthenium according to the first aspect, the solid or liquid containing ruthenium used in the ruthenium-containing gas generation step is derived from the alkali melt.

[0009] A fourth aspect of the present invention is The step of recovering ruthenium comprises: The method for recovering ruthenium according to the first aspect above further comprises a third aeration step of aerating the ruthenium-containing gas through an alkaline solution after the second aeration step.

[0010] A fifth aspect of the present invention is In the method for recovering ruthenium according to the first aspect, the ruthenium-containing gas is generated without adding an oxidizing agent in the ruthenium-containing gas generation step.

[0011] A sixth aspect of the present invention is a method for manufacturing a semiconductor device comprising: In the method for recovering ruthenium according to the first aspect, in the first aeration step, the pH of the liquid before aeration with the ruthenium-containing gas is adjusted to 8 or less.

[0012] A seventh aspect of the present invention is the ruthenium-containing gas contains antimony, lead, copper, and arsenic in addition to the ruthenium; In the method for recovering ruthenium according to the first aspect, the antimony, the lead, the copper, and the arsenic are removed in the first aeration step.

[0013] An eighth aspect of the present invention is In the method for recovering ruthenium according to the first aspect, in the ruthenium-containing gas generation step, a solid or liquid containing ruthenium is added to the acid at a rate of 1.0 g / min or less per 1 g of acid.

[0014] A ninth aspect of the present invention is a method for manufacturing a semiconductor device comprising: In the method for recovering ruthenium according to the first aspect, in the ruthenium-containing gas generation step, an acid is added to a solid or liquid containing ruthenium at an addition rate of 100 g / min or more per 1 g of ruthenium. [Effects of the Invention]

[0015] According to one embodiment of the present invention, it is possible to provide a method for recovering ruthenium at a high quality. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a flowchart showing an example of a method for recovering ruthenium according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing an example of an apparatus for recovering ruthenium in the ruthenium recovery step S107 according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Insights gained by the inventor> First, the findings of the inventors will be explained.

[0018] The inventors have conducted extensive research into a method for easily recovering ruthenium from a ruthenium-containing mixture containing ruthenium, antimony, lead, copper, and arsenic (As). As a result, they have found that, for example, by adding a high concentration acid (e.g., sulfuric acid) to an alkali fused solid obtained by solidifying an alkali fused solid, at least to the extent that it counteracts the strong alkali, and then reacting the mixture, a ruthenium-containing gas containing ruthenium can be efficiently generated. This method allows ruthenium to be recovered from the ruthenium-containing gas without performing a reduction step or the like, thereby simplifying the process. Furthermore, it has been found that, in addition to alkali fusion solidification, ruthenium-containing gas can be efficiently generated by adding a high concentration acid to a ruthenium-containing solution obtained by water leaching of alkali fusion solidification, a water leaching residue obtained by water leaching of alkali fusion solidification, a post-acid-addition ruthenium-containing solution obtained by adding an acid to a ruthenium-containing solution, and a post-acid-addition residue obtained by adding an acid to a ruthenium-containing solution, in an amount at least sufficient to counteract the strong alkali, and allowing them to react.

[0019] Ruthenium-containing solutions obtained by water leaching alkali fusion solidification products have a strong alkaline pH, for example, exceeding 12. Therefore, as described in Patent Document 1, it was conventional common knowledge to attempt to recover ruthenium by reduction utilizing this strong alkaline state. Furthermore, it was thought that ruthenium could only exist in a highly alkaline state, and that if the pH were lowered by adding an acid, it would precipitate together with other impurities, making recovery difficult. However, in the above-mentioned method, an acid is intentionally added to the alkali fusion solidification product or the like to neutralize the strong alkaline state, thereby efficiently generating a ruthenium-containing gas.

[0020] Furthermore, the inventors have conducted extensive research into methods for efficiently separating impurities other than ruthenium from a ruthenium-containing gas and recovering high-quality ruthenium. As a result, they have found that ruthenium can be efficiently recovered by performing a first aeration step in which the ruthenium-containing gas is aerated through water or acid, and a second aeration step in which, after the first aeration step, the ruthenium-containing gas is aerated through hydrochloric acid to which a reducing agent (e.g., alcohol or oxalic acid) has been added. In the first aeration step, although the recovery rate of ruthenium is low, impurities other than ruthenium (e.g., antimony, lead, copper, and arsenic) can be removed. Furthermore, in the second aeration step, ruthenium can be efficiently recovered by aerating the ruthenium-containing gas through hydrochloric acid to which a reducing agent has been added.

[0021] These methods make it possible to efficiently recover ruthenium from a ruthenium-containing mixture.

[0022] [Details of the embodiment of the present invention] Next, an embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0023] In this specification, "A to B" means a numerical range of "A or more and B or less."

[0024] <First embodiment of the present invention> First, the ruthenium recovery method of this embodiment will be described. FIG. 1 is a flowchart showing an example of the ruthenium recovery method of this embodiment. As shown in FIG. 1, the ruthenium recovery method of this embodiment is a method of recovering ruthenium, for example, starting from a ruthenium-containing mixture 10 and recovering ruthenium through an alkali melting step S101, a ruthenium-containing gas generation step S106, and a ruthenium recovery step S107. Furthermore, the ruthenium recovery method of this embodiment may further include a water leaching step S102 and an acid addition step S103, as necessary. In FIG. 1, L indicates the liquid side when solid-liquid separation is performed in each step, and S indicates the solid side.

[0025] The ruthenium-containing mixture 10 may contain ruthenium, antimony, lead, copper, and arsenic. The ruthenium-containing mixture 10 may further contain, for example, tellurium (Te), potassium (K), sodium (Na), etc. The ruthenium-containing mixture 10 may be pulverized in advance to form a fine powder (for example, a particle size of 250 μm or less).

[0026] The grade (content) of each metal element contained in the ruthenium-containing mixture 10 is not particularly limited, but may be, for example, 0.01 to 10 wt% ruthenium, 0.01 to 80 wt% antimony, 0.01 to 90 wt% lead, 0.01 to 90 wt% copper, 0.01 to 80 wt% tellurium, 0.01 to 80 wt% arsenic, 0.01 to 10 wt% potassium, and 0.01 to 10 wt% sodium. Note that when the antimony content is 45 wt% or more, a separate step of separating and recovering antimony may be carried out.

[0027] The ruthenium recovery method of this embodiment is particularly effective when the quality (mass%) of ruthenium is lower than those of antimony, lead, copper, and arsenic. Specifically, for example, the quality ratio of ruthenium to antimony (Ru / Sb) in the ruthenium-containing mixture 10 is preferably 0.01 to 1. Also, for example, the quality ratio of ruthenium to lead (Ru / Pb) is preferably 0.01 to 1. Also, for example, the quality ratio of ruthenium to copper (Ru / Cu) is preferably 0.01 to 1. Also, for example, the quality ratio of ruthenium to arsenic (Ru / As) is preferably 0.01 to 1. In particular, when the quality ratio of ruthenium to the sum of lead and antimony (Ru / (Pb+Sb)) is, for example, 0.001 to 1, it is difficult to concentrate ruthenium using conventional methods, but the ruthenium recovery method of this embodiment makes it possible to concentrate ruthenium simply and efficiently.

[0028] (Alkali melting step S101) The alkali melting step S101 is, for example, a step of alkali-melting the ruthenium-containing mixture 10. Specifically, for example, potassium hydroxide is melted at 400 to 450°C, and the ruthenium-containing mixture 10 is mixed and introduced into the melt. Potassium nitrate may be added as an oxidizing agent. The obtained alkali melt is cooled to room temperature, for example, and solidified to obtain an alkali melt solidified product 11.

[0029] The alkali fused solidified material 11 can be used as a ruthenium source (a solid or liquid containing ruthenium) in the ruthenium-containing gas generation step S106. In this case, the water leaching step S102, the acid addition step S103, the reduction step, etc. can be omitted, thereby simplifying the ruthenium recovery process.

[0030] (Water leaching process S102) The water leaching step S102 is a step in which, for example, water is added to the alkali fusion solidified material 11 obtained in the alkali melting step S101 to leach each metal element, thereby obtaining a ruthenium-containing solution 20 containing ruthenium and a water leaching residue 21. This step is called water leaching because water is added. After the water leaching, solid-liquid separation is performed to obtain the ruthenium-containing solution 20 and the water leaching residue 21.

[0031] The ruthenium-containing solution 20 and the water leaching residue 21 can be used as a ruthenium source in the ruthenium-containing gas generation step S106. In this case, the acid addition step S103, the reduction step, etc. can be omitted, and the ruthenium recovery process can be simplified.

[0032] In the water leaching step S102, it is preferable to add water (i.e., dilute with water) to reduce the viscosity of the ruthenium-containing solution 20 so that the reaction between the ruthenium-containing solution 20 and the acid occurs uniformly in the subsequent acid addition step S103. If the pH of the ruthenium-containing solution 20 drops too much due to the addition of water, the pH may be adjusted by adding, for example, an alkaline agent (pH-raising agent). In this case, the alkaline agent may contain a light metal, but preferably does not contain a heavy metal in order to suppress the consumption of acid in the subsequent acid addition step S103.

[0033] (Acid addition step S103) The acid addition step S103 is, for example, a step of adding an acid (sulfuric acid in this embodiment) to the ruthenium-containing solution 20. After the acid addition, solid-liquid separation is performed to obtain a post-acid-addition ruthenium-containing solution 30 containing ruthenium and a post-acid-addition residue 31. Note that the acid addition here is preferably performed under conditions that do not generate a ruthenium-containing gas.

[0034] The post-acid-addition ruthenium-containing solution 30 and the post-acid-addition residue 31 can be used as a ruthenium source in the ruthenium-containing gas generation step S106. In this case, the reduction step and the like can be omitted, and the ruthenium recovery process can be simplified. Furthermore, for example, when the post-acid-addition ruthenium-containing solution 30 is used as a ruthenium source, the contents of antimony, lead, copper, etc. are reduced, and therefore higher quality ruthenium can be recovered.

[0035] In the acid addition step S103, concentrated sulfuric acid or sulfuric acid of a predetermined concentration (for example, 50%) (dilute sulfuric acid) may be added to the ruthenium-containing solution 20. From the viewpoint of carrying out the reaction for precipitating antimony, lead, copper, etc. at an appropriate speed and from the viewpoint of not increasing the amount of liquid too much, it is preferable to add sulfuric acid of a concentration of 30% or more to the ruthenium-containing solution 20, for example.

[0036] (Ruthenium-containing gas generation step S106) The ruthenium-containing gas generation step S106 is a step in which, for example, at least one of the alkali fusion solidified material 11, the ruthenium-containing solution 20, the water leaching residue 21, the post-acid-addition ruthenium-containing solution 30, and the post-acid-addition residue 31 is used as a ruthenium source, and the ruthenium source is mixed with an acid (sulfuric acid in this embodiment) to generate a ruthenium-containing gas 60 containing ruthenium. The ruthenium source used in the ruthenium-containing gas generation step S106 in this embodiment can be said to be derived from the alkali fusion solidified material 11. Specifically, the ruthenium-containing gas 60 is generated by adding an acid to the ruthenium source, or by adding the ruthenium source to the acid. This allows ruthenium to be recovered efficiently.

[0037] In the ruthenium-containing gas generation step S106, it is preferable to add sulfuric acid to the ruthenium source (or add the ruthenium source to the sulfuric acid) at least to the extent that it counteracts the strong alkalinity. This facilitates efficient generation of the ruthenium-containing gas 60. Specifically, for example, it is preferable to mix the ruthenium source with sulfuric acid so that the pH of the ruthenium source mixed with sulfuric acid is less than 11, preferably 10 or less, more preferably 7 or less, even more preferably 3 or less, and particularly preferably 0.5 or less.

[0038] In the ruthenium-containing gas generation step S106, it is preferable to add high-concentration sulfuric acid to the ruthenium source all at once, or to add the ruthenium source to the sulfuric acid little by little. This makes it easier to generate the ruthenium-containing gas 60 efficiently. Specifically, for example, it is preferable to set the sulfuric acid concentration to 50 to 98% and to set the addition rate of the ruthenium source per 1 g of sulfuric acid to 1.0 g / min or less. Furthermore, when sulfuric acid is added to the ruthenium source, it is preferable to set the addition rate of the sulfuric acid per 1 g of ruthenium contained in the ruthenium source to 100 g / min or more.

[0039] In the ruthenium-containing gas generation step S106, it is preferable to generate the ruthenium-containing gas 60 without adding an oxidizing agent (except concentrated sulfuric acid). Examples of the oxidizing agent include bromates, nitrates, hypochlorites, simple halogens, hypobromites, and hypoiomites. If an oxidizing agent such as sodium bromate is added to generate the ruthenium-containing gas 60, the oxidizing agent must be removed in the ruthenium recovery step S107, complicating the process. In contrast, in the method of the present embodiment, the ruthenium-containing gas 60 can be efficiently generated without adding an oxidizing agent, thereby simplifying the process.

[0040] The reaction time in the ruthenium-containing gas generation step S106 can be 1 minute to 360 minutes. It is preferable to set the reaction time to a time sufficient to generate the ruthenium-containing gas 60, and the reaction time can be 10 minutes to 240 minutes, or may be 20 minutes to 180 minutes. Furthermore, the liquid temperature in the ruthenium-containing gas generation step S106 can be 50°C to 95°C, or may be 50°C to 80°C, taking into account the generation rate of the ruthenium-containing gas 60.

[0041] (Ruthenium recovery process S107) The ruthenium recovery step S107 is, for example, a step of recovering ruthenium from the ruthenium-containing gas 60. As shown in Fig. 1, the ruthenium recovery step S107 includes, for example, a first aeration step S108, a second aeration step S109, and a third aeration step S110.

[0042] 2 is a schematic diagram showing an example of an apparatus for recovering ruthenium in the ruthenium recovery step S107. As shown in FIG. 2, the ruthenium-containing gas 60 discharged from the reaction vessel 100 is passed through the liquid in the recovery vessels S1 to S5 in order, and then exhausted by an exhaust pump (not shown) or the like. If ruthenium has been absorbed into the liquid in the recovery vessels S1 to S5 after the gas has been passed through, the ruthenium can be recovered by a known method such as filtration. Note that the method for passing the ruthenium-containing gas 60 through the liquid in the recovery vessels S1 to S5 is not limited to the embodiment shown in FIG. 2, and known apparatuses capable of bringing the ruthenium-containing gas 60 into contact with the liquid, such as a water spray treatment, may also be used.

[0043] By changing the liquid in the recovery vessels S1 to S5 to water or an acid solution, ruthenium can be absorbed into the liquid and recovered. However, simply passing the ruthenium-containing gas 60 through water or an acid solution results in a low ruthenium recovery rate. Furthermore, since the ruthenium-containing gas 60 of this embodiment contains impurities other than ruthenium (antimony, lead, copper, arsenic, etc., which were originally contained in the ruthenium-containing mixture 10), it is preferable to remove these impurities in order to recover high-quality ruthenium. Below, a method for removing impurities other than ruthenium and efficiently recovering high-quality ruthenium will be described.

[0044] (First ventilation step S108) The first aeration step S108 is a step in which, for example, the ruthenium-containing gas 60 is aerated through water or an acid solution to remove impurities (antimony, lead, copper, arsenic, etc.) other than ruthenium contained in the ruthenium-containing gas 60. When the ruthenium-containing gas 60 is aerated through water or an acid solution, the recovery rate of ruthenium is low, but the impurities other than ruthenium can be absorbed into the water or acid solution and removed, making it easier to recover high-quality ruthenium in the second aeration step S109 described below. Furthermore, the pH of the water used in the first aeration step S108 is preferably 8.0 or less.

[0045] The first aeration step S108 is preferably carried out, for example, before the second aeration step S109. This makes it easier to recover high-quality ruthenium in the second aeration step S109. Specifically, for example, as shown in Fig. 2, the liquid in the recovery vessel S1 may be water or an acid solution, and the first aeration step S108 may be carried out in the recovery vessel S1.

[0046] In the first aeration step S108, it is preferable to adjust the pH of the liquid (water or acid solution) before aerating the ruthenium-containing gas 60 to 8 or less. If the liquid is an alkaline solution, a large amount of ruthenium will be absorbed, making it difficult to separate it from other impurities. Furthermore, in the first aeration step S108, an acid solution (e.g., sulfuric acid) may be added to the liquid before aerating the ruthenium-containing gas 60. In this case, for example, gas containing a small amount of ruthenium absorbed in the liquid in the collection vessel S1 is more likely to be regenerated and move to the collection vessels S2 to S5, making it easier to recover high-quality ruthenium in the second aeration step S109. For example, when a ruthenium source and sulfuric acid are mixed in the reaction vessel 100 to generate the ruthenium-containing gas 60, splashes of sulfuric acid may enter the collection vessel S1. Therefore, the above effect can be achieved without adding an acid solution to the liquid in the collection vessel S1.

[0047] The liquid in the recovery vessel (for example, recovery vessel S1) after the first aeration step S108 contains impurities such as antimony, lead, copper, arsenic, etc. in addition to ruthenium. In this case, the liquid in the recovery vessel may be reused as a ruthenium source.

[0048] (Second ventilation step S109) The second aeration step S109 is, for example, a step of aerating the ruthenium-containing gas 60 through hydrochloric acid to which a reducing agent (e.g., alcohol or oxalic acid) has been added after the first aeration step S108, thereby absorbing (recovering) ruthenium in the hydrochloric acid. The reducing agent is a substance that promotes the absorption of ruthenium as ruthenium chloride into a solution containing the reducing agent and hydrochloric acid when the ruthenium-containing gas 60 containing RuO4 is aerated through the solution containing the reducing agent and hydrochloric acid. Examples of reducing agents that can be used in this step include alcohols such as methanol and ethanol, oxalic acid, formic acid, and ascorbic acid. The chemical reaction formulas assumed when methanol, ethanol, and oxalic acid are used as reducing agents are shown below. In this embodiment, a substance that promotes the reaction of reducing RuO4 contained in the ruthenium-containing gas 60 containing RuO4 to RuCl3 is referred to as a reducing agent. 6RuO4+5CH3OH+18HCl=6RuCl3+5CO2+18H2O 12RuO4+5C2H5OH+36HCl=12RuCl3+10CO2+33H2O 2RuO4+5(COOH)2+6HCl=2RuCl3+10CO2+8H2O

[0049] The second aeration step S109 is preferably carried out immediately after the first aeration step S108 without aerating the ruthenium-containing gas 60 through another solution. This improves the recovery rate of ruthenium. Specifically, for example, as shown in FIG. 2, the liquid in the recovery vessel S2 may be hydrochloric acid to which a reducing agent has been added, and the second aeration step S109 may be carried out in the recovery vessel S2. Note that a step of cooling the ruthenium-containing gas 60 and recovering partially recoverable ruthenium as liquid or solid RuO4 may be added.

[0050] If no reducing agent is added to the hydrochloric acid in the second aeration step S109, the recovery rate of ruthenium will be low. Furthermore, if only a reducing agent such as alcohol is used in the second aeration step S109, the ruthenium-containing gas 60 and the reducing agent will react violently, potentially making recovery unsafe. In contrast, by aerating the ruthenium-containing gas 60 through hydrochloric acid to which a reducing agent has been added in the second aeration step S109, the recovery rate of ruthenium can be improved and recovery can be performed safely. Furthermore, if alcohol is added to the hydrochloric acid in the second aeration step S109, the hydrochloric acid and alcohol can be easily volatilized, allowing ruthenium to be easily recovered from the liquid in the recovery container.

[0051] When alcohol (e.g., ethanol or methanol) or oxalic acid is used as the reducing agent in the second aeration step S109, the amount added to the hydrochloric acid is preferably 1 vol% or more and 50 vol% or less. By adding alcohol or oxalic acid in an amount of 1 vol% or more, ruthenium can be recovered more efficiently. On the other hand, adding too much alcohol or oxalic acid can cause an explosive reaction, so safety is improved by adding alcohol or oxalic acid in an amount of 50 vol% or less. In addition, reducing substances containing C, O, and H, such as formic acid and ascorbic acid (vitamin C), can also be used as other reducing agents.

[0052] After the second aeration step S109 is performed, the third aeration step S110 may be performed immediately, or the first aeration step S108 or the second aeration step S109 may be performed repeatedly. In the example shown in Figure 2, the liquid in the recovery containers S3 and S4 is water or an acid solution. That is, after the second aeration step S109 is performed, the first aeration step S108 is performed again. This can further improve the recovery rate of ruthenium.

[0053] (Third ventilation step S110) The second aeration step S109 is, for example, a step of aerating the ruthenium-containing gas 60 (although most of the ruthenium in the gas is absorbed in the second aeration step S109, etc., for convenience, referred to as the ruthenium-containing gas 60) through an alkaline solution after the second aeration step S109 is performed. This allows the acidic gas to be absorbed in the alkaline solution, making it easier to safely exhaust. The third aeration step S110 is preferably performed immediately before exhaust. In the example shown in FIG. 2, the liquid in the recovery container S5 is an alkaline solution.

[0054] Through the above steps, ruthenium can be efficiently recovered from the ruthenium-containing mixture 10. According to the ruthenium recovery method of this embodiment, for example, it is possible to recover 90% by weight or more (more preferably 99% by weight or more) of the ruthenium contained in the ruthenium-containing mixture 10. Furthermore, in the liquid in the recovery container (e.g., recovery container S2) that has undergone the second aeration step S109, it is possible to make the quality ratio of each impurity element relative to ruthenium (As / Ru, Cu / Ru, Pb / Ru, Sb / Ru) or the quality ratio of the total impurity elements relative to ruthenium (As+Cu+Pb+Sb / Ru) 0.1 or less (more preferably 0.01 or less).

[0055] Specifically, for example, NHCl may be allowed to act on the water or acid solution in which the ruthenium-containing gas 60 has been absorbed in the first aeration step S108, the alcohol or hydrochloric acid to which oxalic acid has been added in which the ruthenium-containing gas 60 has been absorbed in the second aeration step S109, and the alkaline solution in which the ruthenium-containing gas 60 has been absorbed in the third aeration step S110 to crystallize Ru, and then the resulting mixture may be heated to 300°C or higher and H gas may be passed through to obtain Ru metal. The chemical reaction formula in this case is shown below. 3NH4Cl+RuCl3=(NH4)3[RuCl6]↓ (NH4)3[RuCl6]+H2=Ru+3HCl↑+NH3↑

[0056] <Other Embodiments of the Present Invention> Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention.

[0057] For example, in the above embodiment, the ruthenium recovery step S107 is described as being performed using the apparatus shown in Fig. 2, with the first aeration step S108, the second aeration step S109, and the third aeration step S110. However, the ruthenium recovery step S107 is not limited to the above-described embodiment. For example, the third aeration step S110 may be omitted. Even in this case, the effect of efficiently recovering ruthenium can be obtained.

[0058] Furthermore, for example, in the above-described embodiment, the case where sulfuric acid is added to the ruthenium source or the ruthenium source is added to sulfuric acid in the ruthenium-containing gas generation step S106 has been described, but hydrochloric acid or nitric acid may be used instead of sulfuric acid in the ruthenium-containing gas generation step S106. [Example]

[0059] Next, examples of the present invention will be described. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

[0060] Example 1 Example 1 is an example in which ruthenium is recovered using an alkali fusion solidified product 11 as a ruthenium source. First, 100 g of a ruthenium-containing mixture 10 having the composition shown in Table 1 was prepared, and subjected to an alkali melting step S101 at 400 to 450°C together with 200 g of KOH. The resulting alkali fusion product was cooled to room temperature and solidified, and 258 g of alkali fusion solidified product 11 was recovered. In Table 1, Ru / M indicates the purity ratio of ruthenium to each element.

[0061] [Table 1]

[0062] In the ruthenium-containing gas generation step S106 of Example 1, 20 g of alkali fused solidified material 11 was mixed with 0.3 L of sulfuric acid having a concentration of 200 g / L in a reaction vessel 100 shown in FIG. 2 to generate a ruthenium-containing gas 60. The addition rate of the ruthenium source per 1 g of sulfuric acid was 0.33 g / min. The reaction time was 120 minutes from the start of mixing through the addition of the alkali fused solidified material 11, and the liquid temperature was maintained at 60°C. The pH of the sulfuric acid after the addition of the ruthenium source was -0.33.

[0063] In the ruthenium recovery step S107 of Example 1, the apparatus shown in Figure 2 was used. 0.6 L of 1 M (mol / L) hydrochloric acid was placed in recovery vessel S1, 0.5 L of 1 M hydrochloric acid with 25 mL of ethanol was placed in recovery vessel S2, 0.495 L of 1 M hydrochloric acid was placed in recovery vessels S3 and S4, and 0.495 L of 1 M aqueous potassium hydroxide solution was placed in recovery vessel S5, and ruthenium-containing gas 60 was passed through. Table 2 shows the element concentrations of the liquid remaining in reaction vessel 100 and the liquids in recovery vessels S1 to S5. The element concentrations were measured using an ICP-OES (Agilent 720, manufactured by Agilent Technologies) (the same applies to subsequent measurements).

[0064] [Table 2]

[0065] As shown in Table 2, the impurity ratio (As+Cu+Pb+Sb / Ru) of the collection vessel S1 after the first aeration step S108 was 0.215, whereas the impurity ratio of the collection vessel S2 after the second aeration step S109 was a low 0.010. From the above, it was confirmed that high-quality ruthenium can be collected by carrying out the second aeration step S109 after carrying out the first aeration step S108.

[0066] Example 2 In the ruthenium-containing gas generation step S106 of Example 2, 60 g of alkali fused solidified material 11 (similar to Example 1) was mixed with 0.5 L of sulfuric acid having a concentration of 200 g / L in a reaction vessel 100 shown in Figure 2 to generate a ruthenium-containing gas 60. The addition rate of the ruthenium source per 1 g of sulfuric acid was 0.60 g / min. The reaction time was 120 minutes from the start of mixing through the addition of the alkali fused solidified material 11, and the liquid temperature was maintained at 60°C.

[0067] 2, 0.5 L of water was placed in recovery vessel S1, 0.5 L of 1 M hydrochloric acid with 25 mL of ethanol was placed in recovery vessel S2, 0.5 L of 1 M hydrochloric acid was placed in recovery vessel S3, 0.495 L of 1 M hydrochloric acid was placed in recovery vessel S4, and 0.495 L of 1 M aqueous potassium hydroxide solution was placed in recovery vessel S5, and ruthenium-containing gas 60 was passed through. Table 3 shows the element concentrations of the liquid remaining in reaction vessel 100 and the liquids in recovery vessels S1 to S5.

[0068] [Table 3]

[0069] As shown in Table 3, the impurity ratio (As+Cu+Pb+Sb / Ru) of the collection vessel S1 after the first aeration step S108 was 0.085, whereas the impurity ratio of the collection vessel S2 after the second aeration step S109 was a low 0.005. From the above, it was confirmed that high-quality ruthenium can be collected by carrying out the second aeration step S109 after carrying out the first aeration step S108.

[0070] Example 3 In the ruthenium-containing gas generation step S106 of Example 3, 100 g of alkali fused solidified material 11 (similar to Example 1) was mixed with 0.5 L of sulfuric acid having a concentration of 200 g / L in a reaction vessel 100 shown in FIG. 2 to generate a ruthenium-containing gas 60. The addition rate of the ruthenium source per 1 g of sulfuric acid was 1.00 g / min. The reaction time was 120 minutes from the start of mixing through the addition of the alkali fused solidified material 11, and the liquid temperature was maintained at 60°C. The pH of the sulfuric acid after the addition of the ruthenium source was -0.33.

[0071] 2, 0.575 L of 1 M nitric acid was placed in recovery vessel S1, 0.5 L of 1 M hydrochloric acid in recovery vessel S2, 0.5 L of 1 M hydrochloric acid with 25 mL of ethanol added in recovery vessel S3, 0.5 L of 1 M hydrochloric acid in recovery vessel S4, and 0.5 L of 1 M aqueous potassium hydroxide solution in recovery vessel S5, and ruthenium-containing gas 60 was passed through. Table 4 shows the element concentrations of the liquid remaining in reaction vessel 100 and the liquids in recovery vessels S1 to S5.

[0072] [Table 4]

[0073] As shown in Table 4, although ruthenium was recovered in recovery vessels S1 and S2 after the first aeration step S108, ruthenium was also recovered in the subsequent recovery vessel S3, confirming that ruthenium cannot be recovered completely by simply repeatedly performing only the first aeration step S108. In contrast, ruthenium was recovered in recovery vessel S3 after the second aeration step S109, and ruthenium was below the lower detection limit in the subsequent recovery vessels S4 and S5, confirming that ruthenium can be recovered efficiently by performing the second aeration step S109.

[0074] Example 4 In the ruthenium-containing gas generation step S106 of Example 4, 40 g of alkali fused solidified material 11 (similar to Example 1) was mixed with 0.5 L of sulfuric acid having a concentration of 200 g / L in a reaction vessel 100 shown in FIG. 2 to generate a ruthenium-containing gas 60. The addition rate of the ruthenium source per 1 g of sulfuric acid was 0.40 g / min. The reaction time was 120 minutes from the start of mixing through the addition of the alkali fused solidified material 11, and the liquid temperature was maintained at 60°C. The pH of the sulfuric acid after the addition of the ruthenium source was -0.33.

[0075] 2, 0.59 L of 1 M nitric acid was placed in recovery vessel S1, 0.5 L of 1 M hydrochloric acid in recovery vessel S2, 0.5 L of 1 M hydrochloric acid with 50 mL of ethanol added in recovery vessel S3, 0.5 L of 1 M hydrochloric acid in recovery vessel S4, and 0.43 L of 1 M aqueous potassium hydroxide solution in recovery vessel S5, and ruthenium-containing gas 60 was passed through. Table 5 shows the element concentrations of the liquid remaining in reaction vessel 100 and the liquids in recovery vessels S1 to S5.

[0076] [Table 5]

[0077] As shown in Table 5, although ruthenium was recovered in the recovery vessels S1 and S2 after the first aeration step S108, ruthenium was also recovered in the subsequent recovery vessel S3, confirming that ruthenium cannot be recovered completely by simply repeatedly performing only the first aeration step S108. In contrast, ruthenium was recovered in the recovery vessel S3 after the second aeration step S109 was performed, and ruthenium was below the lower detection limit in the subsequent recovery vessels S4 and S5, confirming that ruthenium can be recovered efficiently by performing the second aeration step S109.

[0078] Example 5 In the ruthenium-containing gas generation step S106 of Example 5, 40 g of alkali fused solidified material 11 (similar to Example 1) was mixed with 0.5 L of sulfuric acid having a concentration of 200 g / L in a reaction vessel 100 shown in FIG. 2 to generate a ruthenium-containing gas 60. The addition rate of the ruthenium source per 1 g of sulfuric acid was 0.40 g / min. The reaction time was 120 minutes from the start of mixing through the addition of the alkali fused solidified material 11, and the liquid temperature was maintained at 60°C. The pH of the sulfuric acid after the addition of the ruthenium source was -0.33.

[0079] 2, 0.62 L of 1 M hydrochloric acid was placed in recovery vessel S1, 0.5 L of 1 M hydrochloric acid in recovery vessel S2, 0.5 L of 1 M hydrochloric acid with 10 mL of methanol added in recovery vessel S3, 0.515 L of 1 M hydrochloric acid in recovery vessel S4, and 0.4 L of 1 M aqueous potassium hydroxide solution in recovery vessel S5, and ruthenium-containing gas 60 was passed through. Table 6 shows the element concentrations of the liquid remaining in reaction vessel 100 and the liquids in recovery vessels S1 to S5.

[0080] [Table 6]

[0081] As shown in Table 6, the ruthenium concentration in the recovery vessel S3 after the second aeration step S109 was higher than the ruthenium concentrations in the recovery vessels S1 and S2 after the first aeration step S108. From the above, it was confirmed that ruthenium can be efficiently recovered by performing the second aeration step S109.

[0082] Example 6 In the ruthenium-containing gas generation step S106 of Example 6, 50 g of alkali fused solidified material 11 (similar to Example 1) was mixed with 0.5 L of sulfuric acid having a concentration of 200 g / L in a reaction vessel 100 shown in FIG. 2 to generate a ruthenium-containing gas 60. The addition rate of the ruthenium source per 1 g of sulfuric acid was 0.50 g / min. The reaction time was 120 minutes from the start of mixing through the addition of the alkali fused solidified material 11, and the liquid temperature was maintained at 60°C. The pH of the sulfuric acid after the addition of the ruthenium source was -0.33.

[0083] 2, 0.65 L of water was placed in recovery vessel S1, 0.5 L of 1 M hydrochloric acid in recovery vessel S2, 0.5 L of 1 M hydrochloric acid with 5 g of oxalic acid added in recovery vessel S3, 0.5 L of 1 M hydrochloric acid in recovery vessel S4, and 0.5 L of 1 M aqueous potassium hydroxide solution in recovery vessel S5, and ruthenium-containing gas 60 was passed through. Table 7 shows the element concentrations of the liquid remaining in reaction vessel 100 and the liquids in recovery vessels S1 to S5.

[0084] [Table 7]

[0085] As shown in Table 7, it was confirmed that ruthenium could be efficiently recovered even when oxalic acid was used as the reducing agent.

[0086] (Comparative Example 1) Comparative Example 1 is an example in which the second aeration step S109 was not performed. In the ruthenium-containing gas generation step S106 of Comparative Example 1, 60 g of alkali fused solidified material 11 (similar to Example 1) was mixed with 0.5 L of sulfuric acid having a concentration of 200 g / L in a reaction vessel 100 shown in FIG. 2 to generate a ruthenium-containing gas 60. The addition rate of the ruthenium source per 1 g of sulfuric acid was 0.60 g / min. The reaction time was 120 minutes from the start of mixing through the addition of the alkali fused solidified material 11, and the liquid temperature was maintained at 60°C.

[0087] 2, 0.5 L of 1 M hydrochloric acid was placed in recovery vessels S1 to S4, and 0.5 L of 1 M aqueous potassium hydroxide solution was placed in recovery vessel S5, and ruthenium-containing gas 60 was passed through. Table 8 shows the element concentrations of the liquid remaining in reaction vessel 100 and the liquids in recovery vessels S1 to S5.

[0088] [Table 8]

[0089] As shown in Table 8, it was confirmed that ruthenium could not be completely recovered by simply repeating the first aeration step S108, and that this was inefficient. [Explanation of symbols]

[0090] 10 Ruthenium-containing mixtures 11 Alkali fused solid 20 Ruthenium-containing solution 21 Water leaching residue 30 Ruthenium-containing solution after acid addition 31 Residue after acid addition 60 Ruthenium-containing gas 100 reaction vessels S1~S5 Collection containers S101 Alkali fusion process S102 Water leaching process S103 Acid addition process S106 Ruthenium-containing gas generation process S107 Ruthenium recovery process S108 First ventilation process S109 Second ventilation process S110 Third ventilation process

Claims

1. a ruthenium-containing gas generation step of generating a ruthenium-containing gas containing ruthenium from a solid or liquid containing ruthenium; and recovering the ruthenium from the ruthenium-containing gas, The step of recovering ruthenium comprises: a first aeration step of aerating the ruthenium-containing gas through a water or acid solution; a second aeration step of aerating the ruthenium-containing gas through hydrochloric acid containing a reducing agent after the first aeration step.

2. 2. The method for recovering ruthenium according to claim 1, wherein the reducing agent is an alcohol or oxalic acid.

3. The method further comprises a step of alkali-melting a ruthenium-containing mixture containing ruthenium, antimony, lead, copper, and arsenic to obtain an alkali-melt product, 2. The method for recovering ruthenium according to claim 1, wherein the solid or liquid containing ruthenium used in the ruthenium-containing gas generation step is derived from the alkali melt.

4. The step of recovering ruthenium comprises:

2. The method for recovering ruthenium according to claim 1, further comprising a third aeration step of aerating the ruthenium-containing gas through an alkaline solution after the second aeration step.

5. 2. The method for recovering ruthenium according to claim 1, wherein in the ruthenium-containing gas generating step, the ruthenium-containing gas is generated without adding an oxidizing agent.

6. 2. The method for recovering ruthenium according to claim 1, wherein in the first aeration step, the pH of the liquid before aeration with the ruthenium-containing gas is adjusted to 8 or less.

7. the ruthenium-containing gas contains antimony, lead, copper, and arsenic in addition to the ruthenium; 2. The method for recovering ruthenium according to claim 1, wherein the antimony, the lead, the copper, and the arsenic are removed in the first aeration step.

8. 2. The method for recovering ruthenium according to claim 1, wherein in the ruthenium-containing gas generation step, a solid or liquid containing ruthenium is added to the acid at an addition rate of the solid or liquid containing ruthenium per 1 g of the acid of 1.0 g / min or less.

9. 2. The method for recovering ruthenium according to claim 1, wherein in the ruthenium-containing gas generation step, an acid is added to a solid or liquid containing ruthenium at an addition rate of 100 g / min or more per 1 g of ruthenium contained in the solid or liquid containing ruthenium.

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