A method for recovering precious metals from the post-ruodium-distillation solution

Abstract

The present invention discloses a method for recovering precious metals from ruthenium distillate, comprising the following steps: S1: feeding the ruthenium distillate into a reactor, adding thiourea and urea solutions, performing pretreatment and removing impurities, and cooling and filtering to obtain a pretreated liquid; S2: feeding the pretreated liquid into a reactor, adding a mixture of liquid alkali, oxalic acid, and hydrazine hydrate for adjustment to obtain an adjusted liquid; S3: extracting the supernatant of the adjusted liquid in step S2, washing the filter residue with pure water, filtering, and draining the water, the filter residue is used for further recovery and refining of precious metals, and the filtrate is discharged. The present invention uses pretreatment and impurity removal and alkali-ammonia cross-solution to treat the ruthenium distillate to improve the grade of precious metals in the ruthenium distillate. After treatment, the recovery rate of precious metals in the ruthenium distillate reaches more than 99%. The filter residue is flexibly connected to the platinum group metal separation and refining process according to its content, and is used for further recovery of precious metals, effectively solving the problem of precious metal recovery and treatment in the ruthenium distillate.

Description

Technical Field

[0001] The present invention relates to the technical field of refining and recovery of platinum group metals, and in particular to a method for recovering precious metals from ruthenium distillate. Background Art

[0002] Platinum group metals refer to the six metal elements belonging to the 5th and 6th periods of the periodic table, including ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt). They have the advantages of high melting point, high strength, stable electrothermal properties, high resistance to electric spark erosion, excellent corrosion resistance, strong high-temperature oxidation resistance and good catalytic activity. They are widely used in automotive catalysts, electronic products, medical equipment and other fields. Because of their scarce resources, they are called precious metals.

[0003] During the refining and purification of platinum group metals, purified liquid containing varying degrees of precious metals is produced. Due to the relative continuity and irreversibility of the various process steps in the production process, the purified liquid produced cannot be incorporated into the production system for joint processing. Ruthenium distillate is a liquid separated from ruthenium-containing materials through the distillation purification process. The distillate has a high concentration of precious metals and has high economic value and potential application prospects. As production continues and the number of process steps increases, the distillate will gradually accumulate, and the precious metals and impurities in the solution will continue to be enriched, resulting in the gradual diversification of the system components. Therefore, it is urgent to treat the distillate to improve the recovery rate of precious metals. Summary of the Invention

[0004] The present invention provides a method for recovering precious metals from ruthenium distillate, the purpose of which is to pretreat the ruthenium distillate to remove impurities, and then use an alkali-ammonia cross-solution method to improve the grade of precious metals in the ruthenium distillate, thereby improving the recovery rate of precious metals.

[0005] To achieve its purpose, the present invention adopts the following technical solutions:

[0006] A method for recovering precious metals from ruthenium distillate, comprising the following steps:

[0007] S1: The ruthenium distillate is fed into a reactor, heated to 60-65°C, and then thiourea and urea solutions are added. The ruthenium distillate is then kept warm for 1.5-2 hours to pre-treat the ruthenium distillate to remove impurities. The pre-treated solution is then cooled and filtered to obtain the pre-treated solution.

[0008] S2: The pretreated solution obtained in step S1 is fed into a reactor, and after adding liquid caustic soda at room temperature to adjust the pH to 2-3, a mixed solution of oxalic acid and hydrazine hydrate is added, and stirred for 30-40 minutes to adjust the pH to 3-4; after the reaction is stable, liquid caustic soda is added again to adjust the pH to 5-6, and then the mixed solution of oxalic acid and hydrazine hydrate is continued to be added until the pH is 8-9, and stirred for 60-70 minutes to obtain an adjusted solution;

[0009] S3: extract the supernatant of the adjustment solution in step S2, use pure water to wash the filter residue to pH = 7-8, filter and drain the water, the filter residue is used for further recovery and refinement of precious metals, and the filtrate is discharged.

[0010] Furthermore, in step S1, the ratio of ruthenium distillate: thiourea: urea solution is 200: 1-2: 2-3.

[0011] Furthermore, the ruthenium distillation liquid in step S1 is the liquid separated from the ruthenium-containing material during the ruthenium distillation process.

[0012] Furthermore, the volume ratio of the total amount of the mixed solution of oxalic acid and hydrazine hydrate in step S2 to the liquid after ruthenium distillation in step S1 is 1:50-53.

[0013] Furthermore, the reactors used in step S1 and step S2 are both enameled reactors.

[0014] The beneficial effects of the present invention are as follows:

[0015] This method first uses thiourea and urea to pre-treat the ruthenium distillate to remove impurities, then uses alkali ammonia to dissolve, and adds a mixture of liquid alkali, oxalic acid and hydrazine hydrate to the pre-treated liquid to adjust the grade of precious metals in the ruthenium distillate. Finally, the filter residue is washed, filtered and drained of water, and the platinum group metal separation and refining process is flexibly connected according to its precious metal content to further recover precious metals. The recovery rate of precious metals in the ruthenium distillate treated by this method reaches more than 99%. It not only effectively solves the problem of recycling and processing precious metals in the ruthenium distillate and reduces the cycle of realizing this part of precious metals, but also allows the filtrate to be directly discharged. The overall operation is simple, economical and environmentally friendly, the process flow is short, the labor intensity is low, and it is easy to achieve industrial production. It has promotional and application value for the treatment of other precious metal refined liquids. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with specific embodiments:

[0018] In the following examples of the present invention, the ruthenium-containing material is a mineral resource or secondary resource of a platinum group metal (including platinum, palladium, rhodium, iridium, osmium, and ruthenium). After front-end enrichment, the material is subjected to oxidative distillation to separate the ruthenium therein. The separated ruthenium-containing solution is then subjected to reduction precipitation to obtain a ruthenium-containing material. The ruthenium-containing material is then distilled using sulfuric acid and sodium chlorate solutions to produce a ruthenium distillate. The ruthenium distillate is initially acidic. The liquid caustic soda used is sodium hydroxide solution. The oxalic acid and hydrazine hydrate mixture used is prepared by mixing oxalic acid and hydrazine hydrate in a volume ratio of 1:10.

[0019] The recovery effect of the method of the present invention is characterized by the recovery rate of precious metals in the ruthenium distillation liquid, wherein the recovery rate of precious metals in the ruthenium distillation liquid = (element content of the ruthenium distillation liquid - element content of the recovery treatment filtrate) / element content of the ruthenium distillation liquid.

[0020] Example 1

[0021] The present invention is a method for recovering precious metals from ruthenium distillate. Figure 1 As shown, the following steps are included:

[0022] S1: The ruthenium distillate separated from the ruthenium-containing material during the ruthenium distillation process is fed into an enameled reactor, heated to 60°C, and then thiourea and urea solutions are added, wherein the mass ratio of ruthenium distillate:thiourea:urea solution is 200:1:2. The ruthenium distillate is then pretreated and impurities removed by pre-treating the solution for 1.5 hours, and cooled and filtered to obtain a pre-treated solution.

[0023] S2: The pretreated solution obtained in step S1 is fed into an enameled reactor, and after adding liquid caustic soda at room temperature to adjust the pH to 2, a mixture of oxalic acid and hydrazine hydrate is added, stirred for 30 minutes, and the pH is adjusted to 4; after the reaction is stable, liquid caustic soda is added again to adjust the pH to 5, and then the mixture of oxalic acid and hydrazine hydrate is continued to be added until the pH reaches 8, and stirred for 60 minutes to obtain an adjusted solution; the volume ratio of the total amount of the mixture of oxalic acid and hydrazine hydrate to the ruthenium distilled solution is 1:50;

[0024] S3: After the reaction is complete, the supernatant of the regulating solution in step S2 is extracted, and the filter residue is washed with pure water to a pH of 7, filtered and drained of water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content, and used for further recovery and refinement of precious metals, and the filtrate is discharged.

[0025] The elements of the ruthenium distillate were first analyzed, and the results are shown in Table 1. Then, the elements of the filtrate recovered by this method were analyzed, and the results are shown in Table 2. Analysis of Tables 1 and 2 shows that after treatment by this method, the recovery rate of precious metals in the ruthenium distillate was 99.88%.

[0026] Table 1 Elemental analysis of ruthenium liquid after distillation

[0027]

[0028] Table 2 Elemental analysis of filtrate

[0029]

[0030] Example 2

[0031] The present invention is a method for recovering precious metals from ruthenium distillate. Figure 1 As shown, the following steps are included:

[0032] S1: The ruthenium distillate separated from the ruthenium-containing material during the ruthenium distillation process is fed into an enameled reactor, heated to 60°C, and then thiourea and urea solutions are added, wherein the mass ratio of ruthenium distillate:thiourea:urea solution is 200:2:3. The ruthenium distillate is then pretreated and impurities removed by keeping the temperature for 2 hours, and then cooled and filtered to obtain a pretreated liquid;

[0033] S2: The pretreated solution obtained in step S1 is fed into an enameled reactor, and after adding liquid caustic soda at room temperature to adjust the pH to 3, a mixture of oxalic acid and hydrazine hydrate is added, stirred for 35 minutes, and the pH is adjusted to 4; after the reaction is stable, liquid caustic soda is added again to adjust the pH to 6, and then the mixture of oxalic acid and hydrazine hydrate is continued to be added until the pH reaches 9, and stirred for 60 minutes to obtain a regulated solution; the volume ratio of the total amount of the mixture of oxalic acid and hydrazine hydrate to the ruthenium distilled solution is 1:53;

[0034] S3: After the reaction is complete, the supernatant of the regulating solution in step S2 is extracted, and the filter residue is washed with pure water to a pH of 7, filtered and drained of water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content, and used for further recovery and refinement of precious metals, and the filtrate is discharged.

[0035] The elements of the ruthenium distillate were first analyzed, and the results are shown in Table 3. Then, the elements of the filtrate recovered by this method were analyzed, and the results are shown in Table 4. Analysis of Tables 3 and 4 shows that after treatment by this method, the recovery rate of precious metals in the ruthenium distillate was 99.88%.

[0036] Table 3 Elemental analysis of ruthenium liquid after distillation

[0037]

[0038] Table 4 Elemental analysis of filtrate

[0039]

[0040] Example 3

[0041] The present invention is a method for recovering precious metals from ruthenium distillate. Figure 1 As shown, the following steps are included:

[0042] S1: The ruthenium distillate separated from the ruthenium-containing material during the ruthenium distillation process is fed into an enameled reactor, heated to 65°C, and then thiourea and urea solutions are added, wherein the mass ratio of ruthenium distillate:thiourea:urea solution is 200:1:2. The ruthenium distillate is then pretreated and impurities removed by pre-treating the solution for 1.5 hours, and cooled and filtered to obtain a pre-treated solution.

[0043] S2: The pretreated solution obtained in step S1 was fed into an enameled reactor, and after adjusting the pH to 2 by adding liquid caustic soda at room temperature, a mixture of oxalic acid and hydrazine hydrate was added, stirred for 35 minutes, and the pH was adjusted to 3; after the reaction stabilized, liquid caustic soda was added again to adjust the pH to 5, and then the mixture of oxalic acid and hydrazine hydrate was continued to be added to pH = 8, stirred for 70 minutes, and a regulated solution was obtained; the volume ratio of the total amount of the mixture of oxalic acid and hydrazine hydrate to the ruthenium distillate was 1:51;

[0044] S3: After the reaction is complete, the supernatant of the regulating solution in step S2 is extracted, and the filter residue is washed with pure water to a pH of 7, filtered and drained of water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content, and used for further recovery and refinement of precious metals, and the filtrate is discharged.

[0045] The elements of the ruthenium distillate were first analyzed, and the results are shown in Table 5. The elements of the filtrate recovered by this method were then analyzed, and the results are shown in Table 6. Analysis of Tables 5 and 6 shows that after treatment by this method, the recovery rate of precious metals in the ruthenium distillate was 99.82%.

[0046] Table 5 Elemental analysis of ruthenium liquid after distillation

[0047]

[0048] Table 6 Elemental analysis of filtrate

[0049]

[0050] Example 4

[0051] The present invention is a method for recovering precious metals from ruthenium distillate. Figure 1 As shown, the following steps are included:

[0052] S1: The ruthenium distillate separated from the ruthenium-containing material during the ruthenium distillation process is fed into an enameled reactor, heated to 65°C, and then thiourea and urea solutions are added, wherein the mass ratio of ruthenium distillate:thiourea:urea solution is 200:2:2. The ruthenium distillate is then pretreated and impurities removed by pre-treating the solution for 2 hours, and cooled and filtered to obtain a pre-treated solution.

[0053] S2: The pretreated solution obtained in step S1 is fed into an enameled reactor, and after adding liquid caustic soda at room temperature to adjust the pH to 3, a mixture of oxalic acid and hydrazine hydrate is added, stirred for 40 minutes, and the pH is adjusted to 4; after the reaction is stable, liquid caustic soda is added again to adjust the pH to 6, and then the mixture of oxalic acid and hydrazine hydrate is continued to be added until the pH reaches 9, and stirred for 70 minutes to obtain a regulated solution; the volume ratio of the total amount of the mixture of oxalic acid and hydrazine hydrate to the ruthenium distilled solution is 1:53;

[0054] S3: After the reaction is complete, the supernatant of the regulating solution in step S2 is extracted, and the filter residue is washed with pure water to a pH of 8, filtered and drained of water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content, and used for further recovery and refinement of precious metals, and the filtrate is discharged.

[0055] The elements of the ruthenium distillate were first analyzed, and the results are shown in Table 7. The elements of the filtrate recovered by this method were then analyzed, and the results are shown in Table 8. Analysis of Tables 7 and 8 shows that after treatment by this method, the recovery rate of precious metals in the ruthenium distillate was 99.87%.

[0056] Table 7 Elemental analysis of ruthenium liquid after distillation

[0057]

[0058] Table 8 Elemental analysis of filtrate

[0059]

Claims

1. A method for recovering precious metals from ruthenium distillate, characterized in that: The following steps are involved: S1: The ruthenium distillate is fed into a reactor, heated to 60-65°C, and then thiourea and urea solutions are added. The ruthenium distillate is then kept warm for 1.5-2 hours to pre-treat the ruthenium distillate to remove impurities. The pre-treated solution is then cooled and filtered to obtain the pre-treated solution. S2: The pretreated solution obtained in step S1 is fed into a reactor, and after adding liquid caustic soda at room temperature to adjust the pH to 2-3, a mixture of oxalic acid and hydrazine hydrate is added, stirred for 30-40 minutes, and the pH is adjusted to 3-4; after the reaction is stable, liquid caustic soda is added again to adjust the pH to 5-6, and then the mixture of oxalic acid and hydrazine hydrate is continued to be added until the pH is 8-9, and stirred for 60-70 minutes to obtain an adjusted solution; S3: extract the supernatant of the adjustment solution in step S2, use pure water to wash the filter residue to pH = 7-8, filter and drain the water, the filter residue is used for further recovery and refinement of precious metals, and the filtrate is discharged.

2. The method for recovering precious metals from ruthenium distillate according to claim 1, wherein: In step S1, the mass ratio of the ruthenium distillate: thiourea: urea solution is 200:1-2:2-3.

3. The method for recovering precious metals from ruthenium distillate according to claim 2, wherein: The ruthenium distillation liquid in step S1 is the liquid separated from the ruthenium-containing material during the ruthenium distillation process.

4. The method for recovering precious metals from ruthenium distillate according to claim 3, wherein: The volume ratio of the total amount of the mixed solution of oxalic acid and hydrazine hydrate in step S2 to the volume of the solution after ruthenium distillation in step S1 is 1:50-53.

5. The method for recovering precious metals from ruthenium distillate according to claim 4, wherein: The reactors used in step S1 and step S2 are both enameled reactors.

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