Method for recovering precious metal from ruthenium distillation liquid

Abstract

The method comprises the following steps that S1, the ruthenium after-distillation liquid is fed into a reaction kettle, thiourea and a urea solution are added, pretreatment impurity removal is carried out, and after cooling and filtering, a pretreated liquid is obtained; s2, feeding the pretreated liquid into a reaction kettle, and adding liquid caustic soda and a mixed solution of oxalic acid and hydrazine hydrate for regulation to obtain a regulated solution; and S3, supernate of the adjusting liquid in the step S2 is extracted, filter residues are washed, filtered and drained through pure water, the filter residues are used for further recycling and refining precious metal, and filtrate is discharged. According to the method, the ruthenium after-distillation liquid is treated through pretreatment impurity removal and alkali-ammonia cross dissolution, so that the grade of precious metal in the ruthenium after-distillation liquid is improved, the recovery rate of the precious metal in the treated ruthenium after-distillation liquid reaches 99% or above, and filter residues are flexibly linked with the platinum group metal separation and refining process according to the content of the filter residues and are used for further recovering the precious metal; and the problem of recovery treatment of the noble metal in the ruthenium distilled liquid is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of platinum group metal refining and recovery, and particularly relates to a method for recovering precious metals from ruthenium distillation residue solution. Background Art

[0002] Platinum group metals refer to six metallic elements in 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 fields such as automotive catalysts, electronic products, and medical equipment. Due to their rare resources, they are called precious metals.

[0003] During the refining and purification process of platinum group metals, purified solutions containing precious metals in varying degrees are produced. Due to the relative continuity and irreversibility between the various technological processes in the production process, the produced purified solutions cannot be incorporated into the production system for combined treatment. Ruthenium distillation residue solution is the liquid separated from ruthenium-containing materials through the distillation and purification process. The concentration of precious metals in the distillation residue solution is relatively high, and it has high economic value and potential application prospects. With the continuous progress of production and the increase in technological steps, the distillation residue solution will gradually accumulate, and the precious metals and impurities in the solution will also continuously enrich, resulting in the gradual diversification of the system composition. Therefore, it is urgent to treat the distillation residue solution 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 distillation residue solution, aiming to pre-treat and remove impurities from the ruthenium distillation residue solution, and then use the alkali-ammonia cross-dissolution method to improve the grade of precious metals in the ruthenium distillation residue solution, thereby improving the recovery rate of precious metals.

[0005] To achieve this purpose, the present invention adopts the following technical solutions: A method for recovering precious metals from ruthenium distillation residue solution, comprising the following steps: S1: Feed the ruthenium distillation residue solution into a reaction kettle, heat it to 60 - 65°C, add thiourea and urea solution, then keep it warm for 1.5 - 2 h to pre-treat and remove impurities from the ruthenium distillation residue solution, and obtain the pre-treated solution after cooling and filtration; S2: Feed the pre-treated solution obtained in step S1 into a reaction kettle, add liquid alkali at room temperature to adjust the pH to 2 - 3, then add a mixed solution of oxalic acid and hydrazine hydrate, stir for 30 - 40 min, and adjust the pH to 3 - 4; after the reaction is stable, add liquid alkali again to adjust the pH to 5 - 6, then continue to add the mixed solution of oxalic acid and hydrazine hydrate until the pH reaches 8 - 9, and stir for 60 - 70 min to obtain the adjusted solution; S3: Extract the supernatant of the regulating liquid in step S2, wash the filter residue with pure water until the pH is 7 - 8, filter and drain the water, and use the filter residue for further recovery and refining of precious metals, and discharge the filtrate.

[0006] Further, in step S1, the volume ratio of ruthenium distillation residue liquid: thiourea: urea solution is 200: 1 - 2: 2 - 3.

[0007] Further, the ruthenium distillation residue liquid in step S1 is the liquid separated from ruthenium-containing materials during the ruthenium distillation process.

[0008] Further, the total volume ratio of the mixed liquid of oxalic acid and hydrazine hydrate in step S2 to the volume of the ruthenium distillation residue liquid in step S1 is 1: 50 - 53.

[0009] Further, the reaction kettles used in steps S1 and S2 are both enamel reaction kettles.

[0010] The beneficial effects of the present invention are as follows: This method first uses thiourea and urea to pretreat and remove impurities from the ruthenium distillation residue liquid, and then uses alkali-ammonia cross-dissolution. Add liquid alkali and the mixed liquid of oxalic acid and hydrazine hydrate to the pretreated liquid for adjustment to improve the grade of precious metals in the ruthenium distillation residue liquid. Finally, wash the filter residue, filter and drain the water, and flexibly connect the separation and refining processes of platinum group metals according to its precious metal content for further recovery of precious metals. After treatment with this method, the recovery rate of precious metals in the ruthenium distillation residue liquid reaches more than 99%. It not only effectively solves the problem of recovery and treatment of precious metals in the ruthenium distillation residue liquid, reduces the realization cycle of this part of precious metals, but also can directly discharge the filtrate. The overall operation is simple, economically environmentally friendly, the process flow is short, the labor intensity is small, and it is easy to realize industrial production, and has popularization and application value for the treatment of other precious metal refining residue liquids. Description of the Drawings

[0011] Figure 1 is the process flow chart of the present invention. Detailed Embodiments

[0012] The following further illustrates the present invention in conjunction with specific embodiments: In the following embodiments of the present invention, the ruthenium-containing material is a mineral resource or secondary resource of platinum group metals (including platinum, palladium, rhodium, iridium, osmium, ruthenium, etc.). After preliminary enrichment treatment, ruthenium in the material is separated by the oxidation distillation method. The separated ruthenium-containing solution is precipitated by the reduction method to obtain a ruthenium-containing material. The ruthenium-containing material is then distilled with sulfuric acid and sodium chlorate solution to produce ruthenium distillation residue liquid, and the ruthenium distillation residue liquid is initially acidic. All the liquid alkalis used are sodium hydroxide solutions. The mixed liquid of oxalic acid and hydrazine hydrate used is prepared from oxalic acid and hydrazine hydrate according to a volume ratio of 1:10.

[0013] The recovery effect of the method of the present invention is characterized by the recovery rate of precious metals in the ruthenium distillation residue solution. Among them, the recovery rate of precious metals in the ruthenium distillation residue solution = (the element content of the ruthenium distillation residue solution - the element content of the recovered and treated filtrate) / the element content of the ruthenium distillation residue solution.

[0014] Example 1 The present invention relates to a method for recovering precious metals from a ruthenium distillation residue solution. As Figure 1 shown, it includes the following steps: S1: Feed the ruthenium distillation residue solution separated from the ruthenium-containing material during the ruthenium distillation process into an enamel reaction kettle. After heating to 60 °C, add thiourea and urea solution. Among them, the mass ratio of the ruthenium distillation residue solution: thiourea: urea solution is 200:1:2. Then keep it warm for 1.5 h to pre-treat and remove impurities from the ruthenium distillation residue solution. After cooling and filtering, obtain the pre-treated solution; S2: Feed the pre-treated solution obtained in step S1 into an enamel reaction kettle. At room temperature, add liquid caustic to adjust the pH to 2, then add a mixed solution of oxalic acid and hydrazine hydrate, stir for 30 min, and adjust the pH to 4; after the reaction is stable, add liquid caustic again to adjust the pH to 5, then continue to add the mixed solution of oxalic acid and hydrazine hydrate until the pH reaches 8, and stir for 60 min to obtain the adjusted solution; the total volume ratio of the mixed solution of oxalic acid and hydrazine hydrate to the volume of the ruthenium distillation residue solution is 1:50; S3: After the reaction is complete, extract the supernatant of the adjusted solution in step S2, wash the filter residue with pure water until the pH reaches 7, filter and drain the water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content for further recovery and refining of precious metals, and the filtrate is discharged.

[0015] First, analyze the elements of the ruthenium distillation residue solution, and the results are shown in Table 1. Then, analyze the elements of the filtrate recovered and treated by the method of the present invention, and the results are shown in Table 2. By analyzing Tables 1 and 2, it can be seen that after being treated by the method of the present invention, the recovery rate of precious metals in the ruthenium distillation residue solution is 99.88%.

[0016] Table 1 Analysis of elements in the ruthenium distillation residue solution

[0017] Table 2 Analysis of elements in the filtrate

[0018] Example 2 The present invention relates to a method for recovering precious metals from a ruthenium distillation residue solution. As Figure 1 shown, it includes the following steps: S1: Feed the ruthenium distillation mother liquor separated from ruthenium-containing materials during the ruthenium distillation process into an enamel reactor. After heating to 60 °C, add thiourea and urea solution. Among them, the mass ratio of ruthenium distillation mother liquor:thiourea:urea solution is 200:2:3. Then keep warm for 2 h to pre-treat and remove impurities from the ruthenium distillation mother liquor, and obtain the pre-treated solution after cooling and filtration; S2: Feed the pre-treated solution obtained in step S1 into an enamel reactor. At room temperature, add liquid alkali to adjust the pH to 3, then add a mixed solution of oxalic acid and hydrazine hydrate, stir for 35 min, and adjust the pH to 4; after the reaction is stable, add liquid alkali again to adjust the pH to 6, then continue to add the mixed solution of oxalic acid and hydrazine hydrate until the pH is 9, and stir for 60 min to obtain the adjusted solution; the total volume ratio of the mixed solution of oxalic acid and hydrazine hydrate to the volume of the ruthenium distillation mother liquor is 1:53; S3: After the reaction is complete, extract the supernatant of the adjusted solution in step S2, wash the filter residue with pure water until the pH is 7, filter and drain the water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content for further recovery and refining of precious metals, and the filtrate is discharged.

[0019] First, analyze the elements of the ruthenium distillation mother liquor, and the results are shown in Table 3. Then, analyze the elements of the filtrate recovered and treated by this method, and the results are shown in Table 4. By analyzing Tables 3 and 4, it can be seen that after being treated by this method, the recovery rate of precious metals in the ruthenium distillation mother liquor is 99.88%.

[0020] Table 3 Element analysis of ruthenium distillation mother liquor

[0021] Table 4 Element analysis of filtrate

[0022] Example 3 The present invention is a method for recovering precious metals from ruthenium distillation mother liquor, as Figure 1 shown, including the following steps: S1: Feed the ruthenium distillation mother liquor separated from ruthenium-containing materials during the ruthenium distillation process into an enamel reactor. After heating to 65 °C, add thiourea and urea solution. Among them, the mass ratio of ruthenium distillation mother liquor:thiourea:urea solution is 200:1:2. Then keep warm for 1.5 h to pre-treat and remove impurities from the ruthenium distillation mother liquor, and obtain the pre-treated solution after cooling and filtration; S2: Feed the pretreated liquid obtained in step S1 into an enamel reactor. At room temperature, add liquid caustic to adjust the pH to 2, then add a mixed solution of oxalic acid and hydrazine hydrate, stir for 35 min, and adjust the pH to 3. After the reaction stabilizes, add liquid caustic again to adjust the pH to 5, then continue to add the mixed solution of oxalic acid and hydrazine hydrate until the pH reaches 8, and stir for 70 min to obtain a conditioned liquid. The total volume ratio of the mixed solution of oxalic acid and hydrazine hydrate to the volume of the ruthenium-distilled liquid is 1:51. S3: After the reaction is complete, extract the supernatant of the conditioned liquid in step S2, wash the filter residue with pure water until the pH reaches 7, filter and drain the water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content for further recovery and refining of precious metals, and the filtrate is discharged.

[0023] First, analyze the elements of the ruthenium-distilled liquid, and the results are shown in Table 5. Then, analyze the elements of the filtrate recovered and treated by this method, and the results are shown in Table 6. From the analysis of Tables 5 and 6, it can be seen that after being treated by this method, the recovery rate of precious metals in the ruthenium-distilled liquid is 99.82%.

[0024] Table 5 Analysis of Elements in Ruthenium-Distilled Liquid

[0025] Table 6 Analysis of Elements in Filtrate

[0026] Example 4 The present invention is a method for recovering precious metals from ruthenium-distilled liquid, as Figure 1 shown, including the following steps: S1: Feed the ruthenium-distilled liquid separated from ruthenium-containing materials during the ruthenium distillation process into an enamel reactor. After heating to 65 °C, add thiourea and urea solution, where the mass ratio of ruthenium-distilled liquid:thiourea:urea solution is 200:2:2, and then keep it warm for 2 h to pretreat and remove impurities from the ruthenium-distilled liquid. After cooling and filtering, obtain the pretreated liquid. S2: Feed the pretreated liquid obtained in step S1 into an enamel reactor. At room temperature, add liquid caustic to adjust the pH to 3, then add a mixed solution of oxalic acid and hydrazine hydrate, stir for 40 min, and adjust the pH to 4. After the reaction stabilizes, add liquid caustic again to adjust the pH to 6, then continue to add the mixed solution of oxalic acid and hydrazine hydrate until the pH reaches 9, and stir for 70 min to obtain a conditioned liquid. The total volume ratio of the mixed solution of oxalic acid and hydrazine hydrate to the volume of the ruthenium-distilled liquid is 1:53. S3: After the reaction is complete, extract the supernatant of the conditioned liquid in step S2, wash the filter residue with pure water until the pH reaches 8, filter and drain the water. The filter residue can be flexibly connected to the platinum group metal separation and refining process according to its content for further recovery and refining of precious metals, and the filtrate is discharged.

[0027] First, analyze the elements of the ruthenium distillation residue liquid, and the results are shown in Table 7. Then, analyze the elements of the filtrate recovered and treated by this method, and the results are shown in Table 8. From the analysis of Tables 7 and 8, it can be seen that after being treated by this method, the recovery rate of precious metals in the ruthenium distillation residue liquid is 99.87%.

[0028] Table 7 Analysis of Elements in Ruthenium Distillation Residue Liquid

[0029] Table 8 Analysis of Elements in Filtrate

Claims

1. A method for recovering precious metals from ruthenium distillate, characterized in that: The following steps are involved: S1: feeding the ruthenium distilled liquid into a reactor, heating it to 60-65°C, adding thiourea and urea solution, and then keeping the temperature for 1.5-2h to pre-treat and remove impurities from the ruthenium distilled liquid, cooling and filtering to obtain the pre-treated liquid; S2: the pre-treated liquid obtained in step S1 is fed into a reactor, and after adding liquid alkali at room temperature to adjust the pH to 2-3, a mixed solution 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 alkali 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 to pH = 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. A method for recovering precious metals from ruthenium distillate as claimed in claim 1, characterized in that: In step S1, the mass ratio of ruthenium distilled liquid: thiourea: urea solution is 200:1-2:2-3.

3. A method for recovering precious metals from ruthenium distillate as claimed in claim 2, characterized in that: The ruthenium distillation liquid in step S1 is the liquid separated from the ruthenium-containing material during the ruthenium distillation process.

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

5. A method for recovering precious metals from ruthenium distillate as claimed in claim 4, characterized in that: The reaction kettles used in step S1 and step S2 are both enameled reaction kettles.

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