A method for recovering platinum from spent kast catalyst

Abstract

This invention belongs to the field of precious metal secondary resource recycling technology, and relates to a method for recovering platinum from waste cassette catalysts. The invention proposes to reduce the viscosity of the silicone oil medium in the cassette catalyst through dilution, combined with heating, stirring, flocculation, and sedimentation; this achieves silicone oil separation and recovery. The reagents used are simple and readily available, the reaction conditions are mild, and no waste is generated.

Description

Technical Field

[0001] This invention belongs to the field of precious metal secondary resource recycling technology, and relates to a method for recovering platinum from waste cascade catalysts. Background Technology

[0002] Castrol catalyst, also known as platinum water, is a homogeneous platinum catalyst using silicone oil as a medium, and it has important applications in organosilicon synthesis processes. Common methods for recovering valuable metals from spent catalysts include incineration, carrier dissolution, metal dissolution, total dissolution, and pyrometallurgical collection. However, none of these methods can be directly applied to the recovery of platinum from spent castrol catalysts containing silicone oil. Because silicone oil is non-flammable and stable at high temperatures, incineration cannot destroy or volatilize it. The main technical bottleneck in recovering platinum from spent castrol catalysts using wet methods is the strong chemical stability of silicone oil, its high viscosity, and poor dispersibility. Under conventional conditions, acids, alkalis, and high temperatures are unlikely to completely and effectively destroy silicone oil. Furthermore, the encapsulation effect of silicone oil molecules makes direct reduction or precipitation of platinum from silicone oil extremely difficult.

[0003] To address the aforementioned issues, this invention proposes a method of reducing the viscosity of the silicone oil medium in the cassiterite catalyst through dilution, combined with heating, stirring, flocculation, and sedimentation, to achieve the direct reduction and recovery of platinum from spent cassiterite catalyst. Summary of the Invention

[0004] In view of the above-mentioned technical problems, the present invention provides a method for chemical reduction recovery of platinum from waste cassette catalyst. This method can achieve silicone oil separation and recovery; the reagents used are simple and readily available, the reaction conditions are mild, and no waste is generated.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for chemically reducing and recovering platinum from waste cassette catalyst, comprising the following steps:

[0007] Step 1: Slurrying of spent catalyst:

[0008] Mix the waste casseroton catalyst, diluent, and water in a mass ratio of 1:1:5 and stir until homogeneous.

[0009] Step 2: Reduce metallic platinum:

[0010] Heat the homogeneous liquid obtained in step one to 80°C, slowly add platinum reducing agent, maintain the temperature at 80°C and stir for 2 hours, add flocculant and continue stirring for 0.5 hours;

[0011] Step 3: Filtration and washing

[0012] The reduced liquid obtained in step two was naturally cooled and allowed to stand. The aqueous phase and organic phase were separated and filtered. The obtained platinum black was stirred and washed three times with diluent. After filtration, the organic phase was a mixture of silicone oil and diluent. The silicone oil and diluent were separated by vacuum distillation. The separated diluent was returned to step one as a diluent.

[0013] Step 4: Burning

[0014] Platinum black obtained in step three was placed in a high-temperature furnace at 800℃ and calcined for 2 hours to obtain sponge platinum.

[0015] Furthermore, in steps one and three, the diluent is a low-viscosity organic solvent that is miscible with silicone oil.

[0016] Preferably, the diluent is gasoline or kerosene.

[0017] Furthermore, in step one, the water is deionized water.

[0018] Furthermore, in step two, the platinum reducing agent is hydrazine hydrate, and the amount of hydrazine hydrate used is 1.5 to 2 times the stoichiometric amount.

[0019] Furthermore, in step two, the flocculant is 1‰ polyacrylamide hydrosol, and the amount of flocculant used is 1% of the volume of the reaction liquid.

[0020] Furthermore, in step three, the settling time is 12 hours or more.

[0021] Furthermore, in step three, the amount of detergent used each time is calculated based on a liquid-to-solid mass ratio of 1:3 to 1:5.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0023] (1) The viscosity of the silicone oil medium in the waste cassiterite catalyst is reduced by dilution and slurrying. Combined with stirring and heating measures, the dispersibility of silicone oil is improved, the kinetic conditions of the reduction reaction are enhanced, and the platinum reduction rate is increased.

[0024] (2) The platinum reduction process does not destroy the molecular structure of the catalyst medium—silicone oil, and the separation and recovery of silicone oil and diluent can be achieved by vacuum distillation.

[0025] (3) The reagents used are simple and readily available, the reaction conditions are mild, and no waste is generated. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] A method for chemically reducing and recovering platinum from waste cassette catalyst, comprising the following steps:

[0028] Step 1: Slurrying of spent catalyst:

[0029] Mix the waste casseroton catalyst, diluent, and water in a mass ratio of 1:1:5 and stir until homogeneous.

[0030] Step 2: Reduce metallic platinum:

[0031] Heat the homogeneous liquid obtained in step one to 80°C, slowly add platinum reducing agent, maintain the temperature at 80°C and stir for 2 hours, add flocculant and continue stirring for 0.5 hours;

[0032] Step 3: Filtration and washing

[0033] The reduced liquid obtained in step two was naturally cooled and allowed to stand. The aqueous phase and organic phase were separated and filtered. The obtained platinum black was stirred and washed three times with diluent. After filtration, the organic phase was a mixture of silicone oil and diluent. The silicone oil and diluent were separated by vacuum distillation. The separated diluent was returned to step one as a diluent.

[0034] Step 4: Burning

[0035] Platinum black obtained in step three was placed in a high-temperature furnace at 800℃ and calcined for 2 hours to obtain sponge platinum.

[0036] Furthermore, in steps one and three, the diluent is a low-viscosity organic solvent that is miscible with silicone oil.

[0037] Preferably, the diluent is gasoline or kerosene.

[0038] Furthermore, in step one, the water is deionized water.

[0039] Furthermore, in step two, the platinum reducing agent is hydrazine hydrate, and the amount of hydrazine hydrate used is 1.5 to 2 times the stoichiometric amount.

[0040] Furthermore, in step two, the flocculant is 1‰ polyacrylamide hydrosol, and the amount of flocculant used is 1% of the volume of the reaction liquid.

[0041] Furthermore, in step three, the settling time is 12 hours or more.

[0042] Furthermore, in step three, the amount of detergent used each time is calculated based on a liquid-to-solid mass ratio of 1:3 to 1:5.

[0043] All diluents and reducing agents used in the above steps are of analytical grade.

[0044] Example 1.

[0045] 2 kg of spent casserotonite catalyst (platinum mass percentage: 6.87%) was mixed with 2 kg of kerosene and 10 kg of water and stirred until homogeneous. The mixture was heated to 80°C, and 65 mL of 85% hydrazine hydrate was slowly added while stirring. The temperature was maintained, and the mixture was stirred for 2 hours. Then, 150 mL of flocculant was added, and stirring continued for 30 minutes. After the reaction was complete, the mixture was allowed to cool naturally and stand for 12 hours. The phases were separated, and the aqueous and organic phases were filtered separately. The resulting platinum black was washed three times with 500 mL of kerosene each time, with stirring time of 30 minutes. After washing, the platinum black was transferred to a porcelain dish, dried, and then calcined in a furnace at 800°C for 2 hours. 131.40 g of sponge platinum was obtained, with a platinum mass fraction of 99.5% and a direct platinum recovery rate of 95.16%.

[0046] Example 2.

[0047] 2 kg of spent casserotonite catalyst (platinum mass percentage: 6.87%) was mixed with 2 kg of gasoline and 10 kg of water and stirred until homogeneous. The mixture was heated to 80°C, and 65 mL of 85% hydrazine hydrate was slowly added while stirring. The temperature was maintained, and the mixture was stirred for 2 hours. Then, 150 mL of flocculant was added, and stirring continued for 30 minutes. After the reaction was complete, the mixture was allowed to cool naturally and stand for 12 hours. The phases were separated, and the aqueous and organic phases were filtered separately. The obtained platinum black was washed three times with gasoline (500 mL each time, stirring for 30 minutes each time). After washing, the platinum black was transferred to a porcelain dish, dried, and then calcined in a furnace at 800°C for 2 hours. 131.83 g of sponge platinum was obtained, with a platinum mass fraction of 99.5% and a direct platinum recovery rate of 95.46%.

Claims

1. A method for chemically reducing and recovering platinum from waste cassette catalyst, characterized in that, The specific steps include: Step 1: Slurrying of spent catalyst: Mix the waste casseroton catalyst, diluent, and water in a mass ratio of 1:1:5 and stir until homogeneous. Step 2: Reduce metallic platinum: Heat the homogeneous liquid obtained in step one to 80°C, slowly add platinum reducing agent, maintain the temperature at 80°C and stir for 2 hours, add flocculant and continue stirring for 0.5 hours; Step 3: Filtration and washing The reduced liquid obtained in step 2 was naturally cooled and allowed to stand. The aqueous phase and organic phase were separated and filtered separately. The obtained platinum black was stirred and washed three times with diluent. The organic phase obtained after filtration was a mixture of silicone oil and diluent. The silicone oil and diluent were separated by vacuum distillation. The separated diluent was returned to step 1 as a diluent. Step 4: Burning The platinum black obtained in step three was placed in a high-temperature furnace at 800℃ and calcined for 2 hours to obtain sponge platinum; In steps one and three, the diluent is a low-viscosity organic solvent, such as gasoline or kerosene, that is miscible with silicone oil.

2. The method for chemically reducing and recovering platinum from waste casseroles according to claim 1, characterized in that, In step one, the water is deionized water.

3. The method for chemically reducing and recovering platinum from waste casseroles according to claim 1, characterized in that, In step two, the platinum reducing agent is hydrazine hydrate, and the amount of hydrazine hydrate used is 1.5 to 2 times the theoretical stoichiometric amount.

4. The method for chemically reducing and recovering platinum from waste casseroles according to claim 1, characterized in that, In step two, the flocculant is 1‰ polyacrylamide hydrosol, and the amount of flocculant used is 1% of the volume of the reaction liquid.

5. The method for chemically reducing and recovering platinum from waste casseroles according to claim 1, characterized in that, In step three, the settling time is more than 12 hours.

6. The method for chemically reducing and recovering platinum from waste casseroles according to claim 1, characterized in that, In step three, the amount of detergent used each time is calculated based on a liquid-to-solid mass ratio of 1:3 to 1:5.