A method for recovering the noble metal palladium from a palladium-containing waste solution

Abstract

This invention relates to the development of a stable and widely applicable method for recovering palladium, a precious metal. The method utilizes an ion exchange + incineration + refining process to recover palladium from palladium-containing wastewater. The process is simple, generates no new waste, and the equipment can be reused, resulting in low subsequent recovery costs.

Description

Technical Field

[0001] This invention relates to the field of precious metal extraction technology, and more specifically to a method for recovering palladium from palladium-containing waste liquid. Background Technology

[0002] Palladium catalysts play a crucial role in the pharmaceutical industry, enabling the synthesis of essential drugs and complex molecules. In recent years, the pharmaceutical industry's reliance on palladium catalysis has surged; however, its natural abundance is limited, thus necessitating the development of sustainable palladium catalyst recovery and recycling strategies.

[0003] Pharmaceutical manufacturing processes generate large amounts of wastewater containing trace amounts of palladium. Traditionally, palladium recovery is achieved using methods such as chemical precipitation, membrane separation, and solvent extraction. However, chemical precipitation consumes large amounts of solvent, has poor selectivity, and generates significant amounts of waste. Membrane separation is generally used for enrichment, and membrane technologies for complex environments are not yet mature. Solvent extraction has stringent requirements and poor selectivity. Therefore, developing a stable and universally applicable process is urgently needed. Based on this, a process for recovering palladium from palladium-containing wastewater has been developed. Summary of the Invention

[0004] This invention utilizes an ion exchange + incineration + refining process to recover palladium from palladium-containing wastewater. When the palladium-containing wastewater flows through a resin bed, the palladium ions, due to their higher affinity for the ion exchange resin, will exchange with sodium ions on the resin, forming a more stable structure. At this point, the palladium in the wastewater will be exchanged onto the resin. The resin is then incinerated to obtain crude palladium. Because the wastewater contains low-value metals such as copper, iron, and nickel in addition to palladium, these will be mixed in during ion exchange, resulting in impurities in the sintered palladium powder. Therefore, the crude palladium powder obtained in the previous step needs to be refined. The refining process is a wet process, using a series of steps such as acid leaching, liquid-solid separation, and displacement to remove low-value metals and non-metallic substances from the crude palladium powder, yielding pure palladium after refining.

[0005] This invention provides a method for recovering palladium, a precious metal, from palladium-containing wastewater, comprising the following steps:

[0006]

[0007] Step 1: Pass palladium-containing waste liquid through resin column ion exchange;

[0008] Step 2: High-temperature incineration of palladium-containing resin;

[0009] Step 3: Refine the crude palladium powder obtained in the previous step.

[0010] Preferably, the resin column ion exchange in step one is performed using an ion exchange resin device;

[0011] More preferably, a three-stage ion exchange resin device is used for resin column ion exchange in step one.

[0012] Preferably, the resin used for ion exchange in step one is a sodium-type cation exchange resin or a hydrogen-type cation exchange resin.

[0013] More preferably, the resin used for ion exchange in step one is a sodium-type cation exchange resin.

[0014] Preferably, the amount of resin filling the resin column in step one is 70-80%.

[0015] Preferably, the resin used in step one needs to be activated with a 5% to 10% alkaline solution;

[0016] More preferably, the resin used in step one needs to be activated with a 6% alkali solution.

[0017] Preferably, the incineration temperature in step two is 700–800°C.

[0018] Preferably, the refining method used in step three is wet refining.

[0019] Preferably, the steps in step three using wet refining include: acid leaching, liquid-solid separation, and displacement.

[0020] Beneficial effects

[0021] This invention utilizes an ion exchange + incineration + refining process to recover palladium from palladium-containing wastewater. The process involves enriching palladium using resin and simultaneously designing an ion exchange device. The technology is mature, widely applicable, and provides a solution for precious metal recovery under complex conditions. Furthermore, the ion exchange + incineration refining process is simple, does not generate new waste, and the accompanying equipment can be reused, resulting in lower subsequent recovery costs. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention.

[0023] Figure 1 This is a diagram of the ion exchange equipment for the three-stage ion exchange resin device used in step one of this invention. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented under the premise of the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0025] Example 1

[0026] A total of 7 tons of palladium-containing wastewater was collected, which, after content analysis, contained 775g of palladium. The main components of this wastewater were tetramethylguanidine and toluene, etc. Furthermore, the wastewater became quite viscous when concentrated to 75% of its remaining weight, making further concentration impossible and discharge difficult. This low-concentration precious metal wastewater could not be directly concentrated. Using this process for palladium recovery, the recovery results are shown in Table 1. The process recovered a total of 595g of palladium, with a recovery rate of 76.7%.

[0027] Table 1. Recovery status of Example 1

[0028] step Palladium content / g Recovery rate / % wastewater 775 / Resin recycling section 700 90.32％ Incineration Refining Section 595 85％ total / 76.7％

[0029] As can be seen from the examples, the ion exchange + incineration refining process adopted in this application is simple, does not generate new waste in the process, and the equipment can be reused. It is also highly versatile and has a high recovery rate.

[0030] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering the noble metal palladium from a palladium-containing waste solution, characterized in that It includes the following steps: Step 1: The palladium-containing waste liquid is passed through a resin column ion exchange device to obtain palladium-containing resin; Step 2: The palladium-containing resin obtained in Step 1 is subjected to high-temperature incineration to obtain crude palladium; Step 3: Refine the crude palladium obtained in the previous step.

2. The method of claim 1, wherein: In step one, the resin column ion exchange is performed using an ion exchange resin device.

3. The method of claim 1, wherein: In step one, a three-stage ion exchange resin device is used for resin column ion exchange.

4. The method of claim 1, wherein: The resin used for ion exchange in step one is selected from either sodium-type cation exchange resin or hydrogen-type cation exchange resin.

5. The method of claim 1, wherein: The resin used for ion exchange in step one is a sodium-type cation exchange resin.

6. The method of claim 1, wherein: In step one, the resin column is filled with 70-80% resin.

7. The method of claim 1, wherein: The resin used in step one needs to be activated with 5% to 10% alkali solution, preferably 6% alkali solution.

8. The method of claim 1, wherein: The incineration temperature in step two is 700–800℃.

9. The method of claim 1, wherein: The refining method used in step three is wet refining.

10. The method of claim 1, wherein: Step three, the refining process using wet refining, includes: acid leaching, liquid-solid separation, and displacement.

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