A process for separating platinum, rhodium, iridium from platinum group metal refining

Abstract

The application discloses a method for separating platinum, rhodium and iridium from platinum group metal refining, and belongs to the technical field of platinum group metal refining. The method takes crude platinum ammonium salt as raw material, controls pH, solid-liquid ratio and reaction temperature after water dissolving, and adds a specific proportion of oxalic acid hydrazine reagent to realize the reduction separation of platinum, rhodium and iridium; the filter residue is sequentially dissolved in aqua regia, nitrate is removed, platinum is precipitated, and high-purity sponge platinum is obtained through calcination; the solution after reduction of the oxalic acid hydrazine is extracted by TBP, rhodium is precipitated, back extraction is carried out, and rhodium powder and iridium powder are respectively prepared through calcination. The rhodium and iridium separation rate reaches 99.7%, the platinum purity reaches 99.8%, the process flow is short, the operation is simple, the reagent corrosion is weak, the method is economic and environmental protection, the platinum group metal separation efficiency and product purity are greatly improved, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of platinum group metals refining technology, and specifically to a method for separating platinum, rhodium, and iridium from platinum group metals refining. Background Technology

[0002] Platinum group metals (platinum, rhodium, iridium, etc.) are rare and precious metals with irreplaceable application value in fields such as catalysis, electronics, aerospace, and precision instruments. In the refining and purification process of platinum group metals, the efficient separation of platinum, rhodium, and iridium is a core step in improving product purity, recovery rate, and economic value.

[0003] Existing platinum group metal separation technologies have many drawbacks: First, the separation reagents are highly corrosive, easily damaging production equipment and increasing maintenance costs; second, the separation efficiency of rhodium and iridium is low, making it difficult to achieve efficient recovery and resulting in insufficient resource utilization; third, the process flow is cumbersome and the operation is complex, leading to high energy consumption and long cycles in industrial production; and fourth, the purity of platinum products is difficult to reach above 99.8%, failing to meet the quality requirements of high-end application scenarios.

[0004] Therefore, there is an urgent need in this field to develop a platinum, rhodium, and iridium separation method that is highly efficient, simple in process, uses environmentally friendly reagents, and is equipment-friendly, in order to solve the pain points of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for separating platinum, rhodium, and iridium from platinum group metal refining. This method solves the problems of low separation efficiency, cumbersome processes, highly corrosive reagents, and insufficient platinum purity in existing technologies, achieving efficient separation and high-purity preparation of platinum, rhodium, and iridium, improving the overall recovery rate of platinum group metals, and reducing production costs.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for separating platinum, rhodium, and iridium from platinum group metal refining includes the following steps: a. Crude platinum ammonium salt is dissolved in water, the pH of the solution is adjusted to 3-4, the solid-liquid ratio is controlled at 1:3-4, the temperature is raised to 65-70℃, hydrazine oxalate reagent is added to carry out the reduction reaction until the solution turns light lemon yellow, the solution is cooled and filtered to obtain the filter residue and the reduced hydrazine oxalate solution; the mass ratio of oxalic acid to hydrazine hydrate in the hydrazine oxalate reagent is 13:1. b. Add aqua regia to the filter residue obtained in step a and dissolve it until the filter residue is completely dissolved, so that the osmium and ruthenium can be volatilized and removed; c. Add a denitrifying agent to the solution obtained in step b to carry out a denitrification reaction until no yellow smoke is produced; the mass ratio of alcohol, hydrogen peroxide and urea in the denitrifying agent is 27:1:1; d. Add pure water to the denitrification solution obtained in step c, boil, cool, and filter. e. Boil the filtrate obtained in step d, add platinum precipitation reagent to carry out platinum precipitation reaction until no precipitate is formed, cool and filter to obtain platinum precipitate and platinum precipitation mother liquor; f. Wash the platinum precipitate obtained in step e with a 15% ammonium chloride solution, and calcine it to obtain sponge platinum; g. Extract the hydrazine oxalate reduced solution obtained in step a with TBP to obtain raffinate and iridium-supported organic phase; add rhodium precipitation reagent to raffinate to carry out rhodium precipitation reaction to obtain rhodium salt; back-extract the iridium-supported organic phase with water to obtain iridium solution; h. The rhodium salt and iridium solution obtained in step g are calcined separately to obtain rhodium powder and iridium powder.

[0007] Preferably, the platinum precipitation reagent in step e is a mixture of tetramethylammonium chloride and polyvinyl alcohol.

[0008] Preferably, the rhodium precipitation reagent in step g is a mixture of pentaethylene hexaammonium and polyvinyl alcohol.

[0009] Preferably, after the platinum precipitation reaction in step e is completed, a sample is taken for testing: no precipitate is formed when tetramethylammonium chloride is added to the filtrate, and the extract layer is colorless when tested with tin dichloride, indicating that the platinum precipitation is complete.

[0010] Preferably, the amount of pure water added in step d is 400L.

[0011] The beneficial effects of the present invention are: 1. Excellent separation efficiency A specific ratio of hydrazine oxalate reagent was used to achieve precise separation of platinum from rhodium and iridium, with a rhodium-iridium separation rate of 99.7% and a platinum purity of 99.8%, far exceeding the level of existing technology.

[0012] 2. Simple and efficient process The process is short and the steps are smoothly connected. There is no need for complicated pre-treatment / post-treatment procedures. The operation is easy to control and it is suitable for large-scale industrial production.

[0013] 3. Equipment-friendly, economical and environmentally friendly Hydrazine oxalate reagent has low corrosiveness, reducing equipment wear and tear; the reagent ratio is precise and the dosage is controllable, resulting in less waste emissions and meeting the requirements of green production.

[0014] 4. High overall recycling value This technology enables the simultaneous separation and high-purity preparation of platinum, rhodium, and iridium, significantly improving the overall recovery rate of platinum group metals and enhancing the economic value of the products. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0017] Example 1 A method for separating platinum, rhodium, and iridium from platinum group metals refining comprises the following steps: 1. Dissolve crude platinum ammonium salt in water, adjust the pH of the solution to 3.5, control the solid-liquid ratio to 1:3.5, heat to 68℃, add hydrazine oxalate reagent (oxalic acid: hydrazine hydrate = 13:1), stir the reaction until the solution turns light lemon yellow, cool and filter to obtain the filter residue and the reduced hydrazine oxalate solution.

[0018] 2. Add aqua regia to the filter residue and stir until the residue is completely dissolved and the osmium and ruthenium are fully volatilized.

[0019] 3. Add a nitrate-removing agent (alcohol:hydrogen peroxide:urea = 27:1:1) to the solution and remove the nitrate until no more yellow smoke is emitted.

[0020] 4. Add 400L of pure water to the denitrification solution, boil, cool, and filter.

[0021] 5. Boil the filtrate, add tetramethylammonium chloride and polyvinyl alcohol mixed platinum precipitation reagent, react until no precipitate is formed, cool and filter; sample and test: no precipitate is formed when tetramethylammonium chloride is added to the filtrate, the extract layer is colorless when tested with tin dichloride, and platinum precipitation is complete.

[0022] 6. Wash the platinum precipitate with a 15% ammonium chloride solution and calcine at high temperature to obtain sponge platinum.

[0023] 7. The hydrazine oxalate reduction solution was extracted with TBP to obtain the raffinate and the iridium-loaded organic phase; the raffinate was added with a rhodium precipitation reagent of pentaethylene hexaammonium and polyvinyl alcohol to precipitate rhodium to obtain rhodium salt; the iridium-loaded organic phase was back-extracted with water to obtain iridium solution.

[0024] 8. Rhodium salt and iridium solution are calcined separately to obtain rhodium powder and iridium powder.

[0025] Test results: Pd 1.35 g / L, Rh 0.542 g / L, Ir 0.453 g / L in crude platinum ammonium salt; Pd 0.003 g / L, Rh 0.001 g / L, Ir 0.002 g / L in platinum precipitation mother liquor; the purity of the obtained platinum was as high as 99.8%, and the separation rate of rhodium and iridium was as high as 99.7%. Table 1 shows the analysis results of the content of each element in crude platinum ammonium salt, and Table 2 shows the statistical results of the analysis results of the content of each element in platinum precipitation mother liquor.

[0026] Table 1. Statistical analysis results of elemental content in crude platinum ammonium salt Table 2. Statistical analysis results of element content in platinum precipitation mother liquor .

[0027] Example 2 A method for separating platinum, rhodium, and iridium from platinum group metals refining comprises the following steps: 1. Dissolve crude platinum ammonium salt in water, adjust the pH of the solution to 3, control the solid-liquid ratio to 1:3, heat to 65℃, add hydrazine oxalate reagent (oxalic acid: hydrazine hydrate = 13:1), stir the reaction until the solution turns light lemon yellow, cool and filter to obtain the filter residue and the reduced hydrazine oxalate solution.

[0028] 2. Add aqua regia to the filter residue and stir until the residue is completely dissolved and the osmium and ruthenium are fully volatilized.

[0029] 3. Add a nitrate-removing agent (alcohol:hydrogen peroxide:urea = 27:1:1) to the solution and remove the nitrate until no more yellow smoke is emitted.

[0030] 4. Add 400L of pure water to the denitrification solution, boil, cool, and filter.

[0031] 5. Boil the filtrate, add a mixture of tetramethylammonium chloride and polyvinyl alcohol as a platinum precipitation reagent, react until no precipitate forms, cool and filter; take samples for testing and ensure they pass.

[0032] 6. Wash the platinum precipitate with a 15% ammonium chloride solution and calcine at high temperature to obtain sponge platinum.

[0033] 7. The hydrazine oxalate reduction solution was extracted with TBP to obtain the raffinate and the iridium-loaded organic phase; the raffinate was added with a rhodium precipitation reagent of pentaethylene hexaammonium and polyvinyl alcohol to precipitate rhodium to obtain rhodium salt; the iridium-loaded organic phase was back-extracted with water to obtain iridium solution.

[0034] 8. Rhodium salt and iridium solution are calcined separately to obtain rhodium powder and iridium powder.

[0035] Test results: Pd 1.35 g / L, Rh 0.542 g / L, Ir 0.453 g / L in crude platinum ammonium salt; Pd 0.005 g / L, Rh 0.003 g / L, Ir 0.002 g / L in platinum precipitation mother liquor; the purity of the obtained platinum was as high as 99.6%, and the separation rate of rhodium and iridium was as high as 99.5%. Table 3 shows the analysis results of the content of each element in crude platinum ammonium salt, and Table 4 shows the statistical results of the analysis results of the content of each element in platinum precipitation mother liquor.

[0036] Table 3. Statistical analysis results of elemental content in crude platinum ammonium salt Table 4. Statistical analysis results of element content in platinum precipitation mother liquor .

Claims

1. A method for separating platinum, rhodium, and iridium from platinum group metal refining, characterized in that, Includes the following steps: a. Crude platinum ammonium salt is dissolved in water, the pH of the solution is adjusted to 3-4, the solid-liquid ratio is controlled at 1:3-4, the temperature is raised to 65-70℃, hydrazine oxalate reagent is added to carry out the reduction reaction until the solution turns light lemon yellow, the solution is cooled and filtered to obtain the filter residue and the reduced hydrazine oxalate solution; the mass ratio of oxalic acid to hydrazine hydrate in the hydrazine oxalate reagent is 13:

1. b. Add aqua regia to the filter residue obtained in step a and dissolve it until the filter residue is completely dissolved, so that the osmium and ruthenium can be volatilized and removed; c. Add a denitrifying agent to the solution obtained in step b to carry out a denitrification reaction until no yellow smoke is produced; the mass ratio of alcohol, hydrogen peroxide and urea in the denitrifying agent is 27:1:1; d. Add pure water to the denitrification solution obtained in step c, boil, cool, and filter. e. Boil the filtrate obtained in step d, add platinum precipitation reagent to carry out platinum precipitation reaction until no precipitate is formed, cool and filter to obtain platinum precipitate and platinum precipitation mother liquor; f. Wash the platinum precipitate obtained in step e with a 15% ammonium chloride solution, and calcine it to obtain sponge platinum; g. Extract the hydrazine oxalate reduced solution obtained in step a with TBP to obtain raffinate and iridium-supported organic phase; add rhodium precipitation reagent to raffinate to carry out rhodium precipitation reaction to obtain rhodium salt; back-extract the iridium-supported organic phase with water to obtain iridium solution; h. The rhodium salt and iridium solution obtained in step g are calcined separately to obtain rhodium powder and iridium powder.

2. The method for separating platinum, rhodium, and iridium from platinum group metal refining according to claim 1, characterized in that, The platinum precipitation reagent mentioned in step e is a mixture of tetramethylammonium chloride and polyvinyl alcohol.

3. The method for separating platinum, rhodium, and iridium from platinum group metal refining according to claim 1, characterized in that, The rhodium precipitation reagent mentioned in step g is a mixture of pentaethylene hexaammonium and polyvinyl alcohol.

4. The method for separating platinum, rhodium, and iridium from platinum group metal refining according to claim 1, characterized in that, After the platinum precipitation reaction in step e is completed, a sample is taken for testing: no precipitate is formed when tetramethylammonium chloride is added to the filtrate, and the extract layer is colorless when tested with tin dichloride, indicating that the platinum precipitation is complete.

5. The method for separating platinum, rhodium, and iridium from platinum group metal refining according to claim 1, characterized in that, The amount of pure water added in step d is 400L.

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