Ruthenium recovery agent and method for recovering ruthenium

Abstract

To provide a ruthenium recovery agent capable of efficiently recovering ruthenium in preference to other platinum group metals by using a wet method and a recovery method.SOLUTION: A ruthenium recovery agent comprises at least one amine compound selected from a predetermined aromatic primary amine compound, or a predetermined aliphatic primary amine compound, and after recovering ruthenium, the ruthenium is a solid insoluble to hydrochloric acid at an any concentration of 1 mol / L or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Ruthenium is a platinum group metal, and its alloys with platinum and palladium are used in electrical contacts, as well as in organic chemistry as a catalyst. Ruthenium is also used in electrical and electronic products, as a base for the recording layer of hard disk drives.

[0003] Ruthenium exists in the form of Ru(III) or Ru(IV) in hydrochloric acid solution, [RuCl6] 3- or [Ru2OCl 10 ] 4- However, it is known that Ru(III) is difficult to recover by commonly used solvent extraction methods due to its inertness, and the binuclear complex of Ru(IV) [Ru2OCl 10 ] 4- There have been no reported cases of recall.

[0004] Ruthenium has traditionally been recovered as RuO4 using an oxidation distillation method (Non-Patent Document 1). However, RuO4 is highly toxic, reactive, and chemically unstable, and explosions have been reported. For this reason, in recent years, it has been considered desirable to recover it using a wet method such as solvent extraction, but there are still few reported examples of ruthenium recycling using a wet method. [Prior art documents] [Patent documents]

[0005] [Non-Patent Document 1] H. Nagai, E. Shibata and T. Nakamura: J. MMIJ, 2013, 129, 694-700. [Non-patent document 2] AV Bashilov et al.: J. Anal. Chem., 2003, 58, 845-851. [Non-patent document 3] T. SUZUKI et al.: Metals, 2018, 8, 558. [Non-patent document 4] K. Matsumoto et al.: ACS Omega, 2019, 4, 1868-1873. Summary of the Invention [Problem to be solved by the invention]

[0006] It is difficult to selectively recover ruthenium in preference to other platinum group metals using a wet process rather than the conventional oxidative distillation method, and an efficient recovery method is needed. [Means for solving the problem]

[0007] As a result of intensive research into the above-mentioned problems, the present inventors have found that Ru can be preferentially and selectively recovered from a hydrochloric acid solution containing platinum or palladium by using a specific amine compound, and have completed the following.

[0008] [1] A ruthenium recovery agent containing at least one amine compound selected from the aromatic primary amine compounds of formula (1) and the aliphatic primary amine compounds of formula (2), which is a solid that is insoluble in hydrochloric acid at a concentration of 1 mol / L or more after recovering ruthenium.

[0009] [ka] (X in formula (1) 1 is hydrogen, R 1 , OR 2 , O-Ph, R 1 is an alkyl group having 1 to 8 carbon atoms, and R 2 is an alkyl group having 1 to 6 carbon atoms.

[0010] [ka] (Y in Equation (2) 1 is an alkyl group having 6 to 18 carbon atoms.

[0011] [2] The amine compound contains an aromatic primary amine compound of the formula (1), and X 1 is an alkyl group having 1 to 8 carbon atoms.

[0012] [3] A method for recovering ruthenium from a mixture containing ruthenium using the ruthenium recovery agent according to [1] or [2], comprising: adding the ruthenium recovery agent and the mixture to hydrochloric acid having a concentration of 1.0 mol / L or more, and allowing the ruthenium to be adsorbed onto the ruthenium recovery agent.

[0013] [4] The method according to [3], wherein the mixture contains at least one selected from platinum and palladium, and ruthenium.

[0014] [5] The method according to [3] or [4], wherein the molar ratio (NH2 / ruthenium) of the amino groups contained in the ruthenium recovery agent to the ruthenium contained in the mixture is 10 or more.

[0015] [6] The method according to any one of [3] to [5], wherein the concentration of the hydrochloric acid is 5.0 mol / L or more.

[0016] [7] A method for recovering ruthenium from a mixture containing ruthenium using a ruthenium recovery agent containing at least one amine compound selected from aromatic primary amine compounds or aliphatic primary amine compounds, the method comprising adding the ruthenium recovery agent, the mixture, and an organic solvent to hydrochloric acid, and recovering a complex of the amine compound and ruthenium chloride in the organic solvent.

[0017] [8] The method according to [7], wherein the organic solvent is any one or a mixture of two or more of chloroform, dichloromethane, toluene, and xylene.

[0018] [9] The method according to [7] or [8], wherein the mixture contains at least one selected from platinum and palladium, and ruthenium.

[0019]

[10] The method according to any one of [7] to [9], wherein the aromatic primary amine compound is a compound represented by the following formula (4):

[0020] [ka] (X in Equation (4) 2 is an alkyl group having 4 to 12 carbon atoms or an alkoxy group having 4 to 8 carbon atoms.

[0021]

[11] The method according to any one of [7] to

[10] , wherein the aliphatic primary amine compound is a compound represented by the following formula (5):

[0022] [ka] (Y in Equation (5) 2 is an alkyl group having 8 to 12 carbon atoms.

[0023]

[12] X 2 is an alkyl group having 4 to 12 carbon atoms. [Effects of the Invention]

[0024] According to the ruthenium recovery agent and the method for recovering ruthenium of the present disclosure, ruthenium can be preferentially and selectively recovered from a mixture containing other platinum group metals. [Brief explanation of the drawings]

[0025] [Figure 1]FIG. 1 is a conceptual diagram showing the experimental procedure of the example (precipitation recovery). [Figure 2] FIG. 2 is a graph showing the recovery rates of ruthenium, palladium, and platinum when the molar ratio of 4-hexylaniline to ruthenium (NH / ruthenium) is set to 30, the shaking time is set to 30 minutes, and the hydrochloric acid concentration is changed in the range from 1 mol / L to 10 mol / L. [Figure 3] FIG. 3 is a graph showing the recovery rates of platinum, palladium, and ruthenium when the hydrochloric acid concentration is 8 mol / L, the shaking time is 30 minutes, and the molar ratio of 4-hexylaniline (NH2 / ruthenium) is changed in the range of 4 to 100. [Figure 4] FIG. 4 is a graph showing the recovery rates of ruthenium, palladium, and platinum when the molar ratio of 4-hexylaniline to ruthenium (NH2 / ruthenium) is set to 30, the hydrochloric acid concentration is set to 8 mol / L, and the shaking time is changed in the range of 1 minute to 1 hour. [Figure 5] Figure 5 shows the UV-visible absorption spectra of a solution in which RuCl3 was dissolved in 10 mol / L hydrochloric acid and a solution in which sodium dithionite was added to the solution. [Figure 6] FIG. 6 is an X-ray photoelectron spectroscopy spectrum of the precipitate prepared using 4-hexylaniline. [Figure 7] FIG. 7 is a graph showing the extraction rate of ruthenium when the shaking time is set to 30 minutes and the molar ratio of 4-hexylaniline (NH2 / ruthenium) is changed in the range of 4 to 100. [Figure 8] FIG. 8 is a graph showing the extraction rate of ruthenium when the molar ratio of 4-hexylaniline (NH2 / ruthenium) is set to 30 and the shaking time is changed in the range of 1 minute to 1 hour. DETAILED DESCRIPTION OF THE INVENTION

[0026] <Ruthenium recovery agent> The ruthenium recovery agent of the present disclosure contains at least one amine compound selected from the aromatic primary amine compounds of formula (1) and the aliphatic primary amine compounds of formula (2), and after recovering ruthenium, becomes a solid that is insoluble in hydrochloric acid at any concentration of 1 mol / L or more.

[0027] Here, the term "ruthenium recovery agent" refers to a recovery agent that can recover ruthenium. Furthermore, "insoluble in hydrochloric acid at any concentration of 1 mol / L or more after ruthenium has been recovered" means that the recovery agent after ruthenium has been recovered is insoluble in at least part of the concentration range of 1 mol / L or more. Furthermore, "after ruthenium recovery" refers to a state in which ruthenium is adsorbed and bound to the recovery agent. In other words, the recovery agent of the present disclosure, with ruthenium adsorbed and bound, is in a solid state that is unnecessary for hydrochloric acid at a concentration of 1 mol / L or more.

[0028] The ruthenium recovery agent of the present disclosure contains an aromatic primary amine compound or an aliphatic primary amine compound as the amine compound.

[0029] (Aromatic primary amine compounds) The aromatic primary amine compound is represented by formula (1).

[0030] [ka] (X in formula (1) 1 is hydrogen, R 1 , OR 2 , O-Ph, R 1 is an alkyl group having 1 to 8 carbon atoms, and R 2 is an alkyl group having 1 to 6 carbon atoms.

[0031] R 1 , R 2 The alkyl group of R may be a straight chain or a branched chain, but is preferably a straight chain. 1is preferably an alkyl group having 4 to 8 carbon atoms, and R 2 is preferably an alkyl group having 6 carbon atoms.

[0032] (Aliphatic primary amine compounds) The aliphatic primary amine compound is represented by formula (2).

[0033] [ka] (Y in Equation (2) 1 is an alkyl group having 6 to 18 carbon atoms.

[0034] Y 1 The alkyl group of Y may be a straight chain or a branched chain, but is preferably a straight chain. 1 The alkyl group is preferably an alkyl group having 6 to 18 carbon atoms, and from the viewpoint of the recovery rate of ruthenium, the upper limit of the number of carbon atoms in the alkyl group is preferably 18 or less, more preferably 16 or less.

[0035] From the viewpoint of ruthenium selectivity, X is used as an amine compound. 1 It is preferable to use a 4-alkylaniline having an alkyl group having 4 to 8 carbon atoms.

[0036] The ruthenium recovery agent of the present disclosure must be a solid that is insoluble in hydrochloric acid at a concentration of 1 mol / L or more after ruthenium recovery, which allows the ruthenium recovery agent after ruthenium recovery to be recovered by a precipitation recovery method.

[0037] The recovery agent before ruthenium recovery may be in either a solid or liquid state. For example, when aniline is used as the amine compound, the recovery agent is liquid before use but precipitates as a solid after ruthenium recovery, and is therefore included in the ruthenium recovery agent of the present disclosure.

[0038] <Ruthenium recovery method (precipitation recovery)> The ruthenium recovery method (precipitation recovery) of the present disclosure is a method for recovering ruthenium from a mixture containing ruthenium using the above-described ruthenium recovery agent, in which the ruthenium recovery agent and the mixture are immersed in hydrochloric acid having a concentration of 1.0 mol / L or more, and the ruthenium is adsorbed onto the ruthenium recovery agent.

[0039] Here, the term "ruthenium-containing mixture" means a mixture containing at least ruthenium, and may further contain other metals or precious metals. According to the findings of the present inventors, even if the mixture contains at least one precious metal other than ruthenium, selected from palladium and platinum, ruthenium can be preferentially recovered using the ruthenium recovery agent of the present disclosure. For example, the ruthenium recovery agent can be applied to the leachate of electrolytic slime obtained in the electrolytic refining process of copper smelting.

[0040] Furthermore, the term "method for recovering ruthenium" means, when a mixture contains ruthenium, recovering ruthenium together with other metals or precious metals, or selectively recovering ruthenium in preference to other metals or precious metals, and preferably means selectively recovering ruthenium in preference to other metals or precious metals.

[0041] In the recovery method (precipitation recovery) of the present disclosure, "containing the ruthenium recovery agent and the mixture in hydrochloric acid having a concentration of 1.0 mol / L or more" can be carried out, for example, by immersing a solid ruthenium recovery agent in a solution in which a waste material containing ruthenium is dissolved in hydrochloric acid.

[0042] From the viewpoint of exhibiting selectivity for ruthenium, the lower limit of the concentration of hydrochloric acid is preferably 1.0 mol / L or more, more preferably 5.0 mol / L or more, even more preferably 6.0 mol / L or more, and particularly preferably 8.0 mol / L or more, and the upper limit is preferably 12 mol / L or less, more preferably 10 mol / L or less.

[0043] The present inventors presume that the following complex is formed in the hydrochloric acid solution containing the above-mentioned recovery agent and Ru(IV).

[0044] [ka] (Z in formula (3) represents a residue of an amine compound.)

[0045] Ru(IV) forms a binuclear complex ([Ru2OCl 10 ] 4- ) is formed. Until now, Ru(III) was thought to be the stable oxidation state, but the present inventors have found through the analysis described below that it is easily oxidized in a hydrochloric acid solution in air and exists mainly as Ru(IV). Furthermore, it is commonly believed by those skilled in the art that an ion pair is formed in which four ammonium cations are bound to a binuclear complex of Ru(IV), a tetravalent anion. However, the present inventors have found through the analysis described below that a complex of the above formula (3) is formed. In the complex of formula (3), eight ammonium cations and four chloride anions are complexed to the anion of the binuclear complex. In formula (3), Z represents the residue of the above-mentioned amine compound. Therefore, when the amine compound is an aromatic primary amine compound, Z is represented by "X 1 -Ph-" and when the amine compound is an aliphatic primary amine compound, Z represents "Y 1 -"

[0046] (molar ratio of ruthenium to recovery agent) In the recovery method (precipitation recovery) of the present disclosure, the molar ratio (NH2 / ruthenium) of the amino groups contained in the ruthenium recovery agent to the ruthenium contained in the mixture is preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, and particularly preferably 25 or more, from the viewpoint of ruthenium recovery rate.

[0047] (Other conditions) As described above, the ruthenium recovery agent of the present disclosure is premised on being insoluble in hydrochloric acid of the above-mentioned predetermined concentration after ruthenium recovery. As long as this premise can be maintained, there are no particular limitations on the temperature, pressure, or atmosphere during ruthenium recovery. Ruthenium can be efficiently recovered even at room temperature, atmospheric pressure, and in the air.

[0048] According to the findings of the present inventors, the time for immersing the recovery agent and mixture in hydrochloric acid is not particularly limited, and ruthenium can be adsorbed and bound to the recovery agent by immersion for a short period of time. However, it is preferable to shake or stir the mixture during immersion. In the method of the present disclosure, selective recovery of ruthenium can be achieved by shaking for a short period of time, for example, 1 minute.

[0049] <Ruthenium recovery method (solvent extraction)> The ruthenium recovery method (solvent extraction) of the present disclosure is a method for recovering ruthenium from a mixture containing ruthenium using a ruthenium recovery agent containing at least one amine compound selected from aromatic primary amine compounds or aliphatic primary amine compounds, in which the ruthenium recovery agent, the mixture, and an organic solvent are added to hydrochloric acid to form a complex between the amine compound and ruthenium chloride, and the complex is recovered in the organic solvent.

[0050] Here, the term "ruthenium-containing mixture" has the same meaning as in the above-mentioned recovery method (precipitation recovery). Furthermore, the "method for recovering ruthenium" has the same meaning as the above-mentioned recovery method (precipitation recovery).

[0051] The ruthenium recovery method (solvent extraction) of the present disclosure uses a ruthenium recovery agent containing at least one amine compound selected from aromatic primary amine compounds or aliphatic primary amine compounds.

[0052] (Aromatic primary amine compounds) The aromatic primary amine compound is represented by the following formula (4).

[0053] [ka] (X in Equation (4) 2 is an alkyl group having 4 to 12 carbon atoms or an alkoxy group having 4 to 8 carbon atoms.

[0054] (Aliphatic primary amine compounds) The aliphatic primary amine compound is represented by the following formula (5).

[0055] [ka] (Y in Equation (5) 2 is an alkyl group having 8 to 12 carbon atoms.

[0056] From the viewpoint of ruthenium recovery rate, the amine compound is X 2 It is preferable to use a 4-alkylaniline having an alkyl group with 4 to 12 carbon atoms, and it is more preferable to use a 4-alkylaniline having an alkyl group with 4 to 6 carbon atoms.

[0057] The recovery method (solvent extraction) of the present disclosure can be divided into, for example, an adding step, a mixing step, and a ruthenium recovery step if each step is described separately, and will be described below in that order.

[0058] (addition process) In the adding step, the ruthenium recovery agent, the mixture containing ruthenium, and the organic solvent are added to hydrochloric acid. The recovery method (solvent extraction) of the present disclosure is characterized in that ruthenium is recovered from a hydrochloric acid solution containing ruthenium using a predetermined ruthenium recovery agent and an organic solvent, and also includes within its scope modifications that do not affect the characteristic. For example, the term "addition" as used herein also includes a modification in which a ruthenium recovery agent and an organic solvent are added to a hydrochloric acid solution in which ruthenium has been dissolved from the beginning, rather than adding a mixture containing ruthenium to hydrochloric acid.

[0059] The ruthenium recovery agent used in the recovery method (solvent extraction) of the present disclosure only needs to be a complex with ruthenium that dissolves in an organic solvent, but the ruthenium recovery agent itself does not necessarily need to dissolve in an organic solvent. In this respect, it differs from conventional solvent extraction methods, and recovery agents that cannot be used in conventional solvent extraction methods can be used, broadening the range of application of recovery agents.

[0060] The molar ratio (NH / ruthenium) of the amino group of the amine compound constituting the ruthenium recovery agent to the ruthenium in the mixture is preferably 4 or more and 100 or less, and from the viewpoint of efficiency, the upper limit is more preferably 50 or less, and even more preferably 30 or less.

[0061] (organic solvent) The organic solvent used in the recovery method (solvent extraction) of the present disclosure is not particularly limited, and various organic solvents can be used as long as they can dissolve the complex of the amine compound and ruthenium chloride. Furthermore, two or more organic solvents may be used in combination. Examples of organic solvents include chloroform, dichloromethane, toluene, and xylene, and mixtures of two or more of these may also be used. Furthermore, solvents that are completely miscible with water cannot be used as the organic solvent.

[0062] (hydrochloric acid) From the viewpoint of the extraction rate of ruthenium, the lower limit of the concentration of hydrochloric acid used in the present invention is preferably 1.0 mol / L or more, more preferably 5.0 mol / L or more, even more preferably 6.0 mol / L or more, and particularly preferably 8.0 mol / L or more. Furthermore, in the method of the present invention, even in high-concentration hydrochloric acid, the following complex can be dissolved in an organic solvent (preferably a chlorine-based organic solvent), so the upper limit of the hydrochloric acid concentration is not particularly limited, but in practice, it is preferably 12.0 mol / L or less, more preferably 10 mol / L or less. In order to achieve high selectivity for ruthenium, it is preferable to set the concentration of hydrochloric acid to 5 mol / L or more.

[0063] (Mixing process) In the mixing step, the above-mentioned ruthenium recovery agent, a mixture containing ruthenium, an organic solvent, and hydrochloric acid are mixed together to form a complex of an amine compound and ruthenium chloride. The mixing can be carried out by shaking or stirring. The shaking and stirring conditions are not particularly limited, and conditions that have been used in solvent extraction so far can be appropriately adopted. The shaking and stirring time is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. There is no particular upper limit, but since the effect of stirring is not observed when it is more than 60 minutes, it is preferable to keep it to 60 minutes or less from the viewpoint of efficiency.

[0064] (Ruthenium recovery process) The complex dissolved in the organic solvent formed in the mixing step can be recovered and subjected to a predetermined purification procedure to recover ruthenium. The purification procedure is not particularly limited, but examples include a method of extracting ruthenium or ruthenium alone with a basic aqueous solution, or a method of burning the complex. Aqueous ammonia can be used as the basic aqueous solution. The concentration of aqueous ammonia is not particularly limited, but it is preferable to use, for example, a concentration of 1 to 5 M. [Example]

[0065] <Precipitate recovery> <Example 1-1> After immersing 4-hexylaniline as a recovery agent in hydrochloric acid containing 1 mM each of platinum, palladium, and ruthenium, the solution was shaken and centrifuged, and the supernatant was recovered.The concentrations of platinum, palladium, and ruthenium contained in the supernatant were analyzed by ICP, and the recovery rates (metal precipitation rates) of platinum, palladium, and ruthenium adsorbed and bound to the recovery agent were calculated.For reference, details of the experimental procedure are shown in Figure 1.

[0066] The recovery rates of platinum, palladium, and ruthenium were confirmed by varying the concentration of hydrochloric acid, the amount of amine added, and the shaking time. The results are shown in Figures 2 to 4.

[0067] Figure 2 shows the recovery rates of platinum, palladium, and ruthenium when the molar ratio of 4-hexylaniline to ruthenium (NH2 / ruthenium) was set to 30, the shaking time was 30 minutes, and the hydrochloric acid concentration was varied from 1.0 mol / L to 10 mol / L. As is clear from Figure 2, 4-hexylaniline exhibited adsorption for all of ruthenium, palladium, and platinum at hydrochloric acid concentrations of 1.0 to 4.0 mol / L. On the other hand, at hydrochloric acid concentrations in the range of 5 mol / L to 10.0 mol / L, it exhibited selective adsorption only for ruthenium.

[0068] Figure 3 shows the recovery rates of platinum, palladium, and ruthenium when the hydrochloric acid concentration was 8 mol / L, the shaking time was 30 minutes, and the molar ratio of 4-hexylaniline (NH2 / ruthenium) was changed in the range of 4 to 100. As is clear from Figure 3, ruthenium was efficiently recovered when the molar ratio of 4-hexylaniline was 10 or higher.

[0069] Figure 4 shows the recovery rates of platinum, palladium, and ruthenium when the molar ratio (NH2 / ruthenium) was set to 30, the hydrochloric acid concentration was set to 8 mol / L, and the shaking time was changed in the range of 1 minute to 1 hour. As is clear from Figure 4, ruthenium was quickly adsorbed to 4-hexylaniline, and there was almost no change in the ruthenium recovery rate even when the shaking time was increased beyond 30 minutes.

[0070] <Examples 1-2 to 1-9> The recovery rate (metal precipitation rate) of ruthenium adsorbed and bound to the recovery agent was calculated by immersing a specified recovery agent shown in Table 1 in hydrochloric acid containing 100 ppm of ruthenium alone, shaking and centrifuging the solution, and recovering the supernatant. The concentration of ruthenium contained in the supernatant was analyzed by ICP, and the recovery rate (metal precipitation rate) of ruthenium adsorbed and bound to the recovery agent was calculated. The concentration of hydrochloric acid and the molar ratio (NH2 / ruthenium) for each example are as shown in Table 1.

[0071] [Table 1]

[0072] As shown in Table 1, it was demonstrated that ruthenium can be recovered by precipitation using amines with specific structures.

[0073] <Comparative Examples 1-1 and 1-2> The ruthenium recovery rate was calculated by conducting a metal recovery test in the same manner as in Examples 1-2 to 1-9 using the specified recovery agent shown in Table 2. The concentration of hydrochloric acid and the molar ratio (NH2 / ruthenium) in each example are as shown in Table 2.

[0074] [Table 2]

[0075] As shown in Table 2, it was shown that even primary amine compounds cannot be used to precipitate and recover ruthenium depending on their molecular structure.

[0076] <Reference example 1-1> RuCl3 was added to 10 mol / L hydrochloric acid and stirred in air to dissolve, and the UV-visible absorption spectrum of the solution was measured. In addition, the reducing agent sodium dithionite was added to the resulting solution until the solution turned pale yellow, and the UV-visible absorption spectrum of the solution was also measured.

[0077] The absorption spectrum is shown in Figure 5. The spectrum of the hydrochloric acid solution in which RuCl3 was dissolved (solid line in Figure 5) was obtained from the Ru(IV) dinuclear complex [RuOCl] described in Non-Patent Document 2 (AV Bashilov et al.: J. Anal. Chem., 2003, 58, 845-851). 10 ] 4- ), which indicates that Ru(III) is oxidized to Ru(IV) by dissolving in hydrochloric acid in air. The spectrum of the solution containing sodium dithionite (dashed line in Figure 5) is consistent with that of the Ru(III) complex ([RuCl6]) described in Non-Patent Document 3 (T. Suzuki et al.: Metals, 2018, 8, 558.). 3-), which indicates that Ru(IV) becomes Ru(III) under the action of a reducing agent.

[0078] <Reference example 1-2> The precipitate obtained in Example 1 was thoroughly washed with hydrochloric acid to remove excess recovery agent, thereby obtaining a solid. X-ray photoelectron spectroscopy (XPS) measurement of this solid was carried out.

[0079] The XPS spectrum is shown in Figure 6. The presence of ruthenium, nitrogen, carbon, and chlorine was confirmed from the XPS spectrum, and the atomic ratio of these elements was calculated to be Ru:N:Cl = 1:4:7. This coincides with the results of the XPS spectrum, as the ratio of Ru:N:Cl = 1:4:7 for the complex of formula (3) using 4-hexylaniline as the recovery agent.

[0080] <Examples 1-10> The Ru(III) solution prepared in Reference Example 1-1 was diluted to an 8 mol / L hydrochloric acid solution containing 100 ppm of ruthenium, and 4-phenoxyaniline was added as a recovery agent. After 30 minutes of shaking and centrifugation, the supernatant was recovered and the concentration of ruthenium contained in the supernatant was analyzed by ICP to calculate the recovery rate of ruthenium. As a result, 60% of the ruthenium was recovered as a precipitate.

[0081] As shown in Example 1-6, 4-phenoxyaniline hardly recovers Ru(IV), but as shown in Example 1-10, it can recover Ru(III). This indicates that the recovery mechanisms of Ru(IV) and Ru(III) are different. Non-Patent Document 4 (K. Matsumoto et al.: ACS Omega, 2019, 4, 1868-1873.) describes the recovery of a Rh(III) complex ([RhCl6] 3- The ion pair structure of Ru(III) and an amine is shown, and the Ru(III) complex ([RuCl6] 3-) is expected to have a similar structure. This ion pair structure consisting of Ru(III) and an amine is significantly different from the ion pair structure consisting of Ru(IV) and an amine shown in formula (3), so the recovery behavior of Ru(III) and Ru(IV) is thought to be different.

[0082] <Solvent extraction> <Examples 2-1 to 2-5> To 1 mL of a hydrochloric acid solution containing ruthenium at the concentration shown in Table 3 and having a predetermined concentration shown in Table 3, the recovery agent shown in Table 3 was added so that the molar ratio to ruthenium (NH2 / ruthenium) was the value shown in Table 3, and 1 mL of the organic solvent shown in Table 3 was added and the mixture was shaken for 30 minutes. The aqueous layer was recovered, and the concentration of ruthenium contained in the aqueous solution was analyzed by ICP to calculate the proportion of ruthenium that had migrated to the organic layer (ruthenium extraction rate). The results are also shown in Table 3.

[0083] [Table 3]

[0084] As shown in Table 3, it was demonstrated that ruthenium can be extracted by solvent using amines with specific structures.

[0085] <Example 2-6> 1 mL of 4-hexylaniline and chloroform were added to 1 mL of an 8 mol / L hydrochloric acid solution containing 100 ppm of ruthenium, and the mixture was shaken. The aqueous layer was collected, and the concentration of ruthenium in the solution was analyzed by ICP to calculate the proportion of ruthenium that had migrated to the organic layer (ruthenium extraction rate). Figures 7 and 8 show the ruthenium extraction rate when the amount of amine added and the shaking time were changed.

[0086] Figure 7 shows the ruthenium extraction rate when the shaking time was 30 minutes and the molar ratio of 4-hexylaniline (NH2 / ruthenium) was changed in the range of 4 to 100. As is clear from Figure 7, ruthenium was efficiently extracted when the molar ratio of 4-hexylaniline was 4 or higher.

[0087] Figure 8 shows the ruthenium extraction rate when the molar ratio of 4-hexylaniline (NH2 / ruthenium) was set to 30 and the shaking time was changed in the range of 1 minute to 1 hour. As is clear from Figure 8, 94% of ruthenium was extracted with shaking for 1 minute, and there was almost no change in the ruthenium extraction rate even when the shaking time was increased.

[0088] <Example 2-7> To 1 mL of 8 mol / L hydrochloric acid containing 1 mM each of palladium, platinum, and ruthenium, 4-hexylaniline was added so that the molar ratio (NH2 / ruthenium) to ruthenium was 30, and 1 mL of toluene was added and the mixture was shaken for 30 minutes. The organic phase was washed twice with 8 M hydrochloric acid, and the resulting aqueous phase was subjected to ICP analysis to calculate the extraction rate of each metal. The results are shown in Table 4.

[0089] [Table 4]

[0090] As shown in Table 4, ruthenium could be selectively extracted.

Claims

1. A selective recovery agent for ruthenium, which contains an aromatic primary amine compound of formula (1) and is a solid that is insoluble in hydrochloric acid at a concentration of 1 mol / L or more after recovering ruthenium. 【Chemical 1】 (X in formula (1) １ is R １ , O-R ２ , O-Ph, and R １ is an alkyl group having 1 to 8 carbon atoms, and R ２ is an alkyl group having 1 to 6 carbon atoms.

2. The amine compound contains an aromatic primary amine compound of the formula (1), and X １ 2. The agent for selectively recovering ruthenium according to claim 1, wherein: is O-R 2 , and R 2 is an alkyl group having 1 to 6 carbon atoms.

3. 3. A method for recovering ruthenium from a mixture containing ruthenium using the selective recovery agent for ruthenium according to claim 1, comprising: adding the ruthenium recovery agent and the mixture to hydrochloric acid having a concentration of 1.0 mol / L or more; and allowing the ruthenium to be adsorbed onto the selective recovery agent for ruthenium.

4. 4. The method of claim 3, wherein the mixture comprises at least one selected from platinum and palladium, and ruthenium.

5. The molar ratio (NH ２ The method according to claim 3 or 4, wherein the ratio of ruthenium to ruthenium is 10 or more.

6. The method according to any one of claims 3 to 5, wherein the concentration of the hydrochloric acid is 5.0 mol / L or more.

7. The method according to claim 3, wherein an organic solvent is further added in the step of incorporating the ruthenium recovery agent and the mixture in hydrochloric acid having a concentration of 1.0 mol / L or more.

8. 8. The method according to claim 7, wherein the organic solvent is any one or a mixture of two or more of chloroform, dichloromethane, toluene, and xylene.

Images