Method for recovering platinum and palladium from silver electrolyte

Abstract

The invention discloses a method for recovering platinum and palladium from silver electrolyte, and belongs to the technical field of recovering platinum and palladium from silver electrolyte. According to the method, the platinum and palladium metals in the silver electrolyte are adsorbed through the activated carbon, and then the adsorbed activated carbon and the flour are mixed and calcined, so that the grade of the platinum and palladium raw materials is improved, the leaching rate and the direct recovery rate in the subsequent platinum and palladium production process are greatly improved, the platinum and palladium content of a slag phase is reduced, meanwhile, the operation is simple, and the labor repetition rate is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of recovering platinum and palladium from silver electrolyte, and particularly relates to a method for recovering platinum and palladium from silver electrolyte. Background Art

[0002] Platinum and palladium are extremely valuable precious metals, widely used in catalysts in chemical, electronic, medical, automobile manufacturing, petroleum industry and high-tech fields (such as aerospace, aviation, navigation, weapons and nuclear energy, etc.). Due to the scarcity of platinum and palladium resources, the content in the earth's crust is extremely low (for example, palladium is about one hundred millionth), and there are few platinum and palladium ores that exist alone. Therefore, it is particularly important to recover platinum and palladium from various by-products and waste liquids.

[0003] During the silver electrolytic refining process, platinum and palladium often enter the electrolyte along with silver because their electric potentials are similar to those of silver. These electrolytes are enriched with a large amount of platinum and palladium. If they are not effectively recovered, it will not only lead to a waste of resources, but also affect the quality of subsequent silver powder products. Adsorption technology, especially activated carbon adsorption technology, has gradually gained attention in the recovery of platinum and palladium. Activated carbon has porosity, high specific surface area and good adsorption properties, and can effectively adsorb metal ions such as platinum and palladium from complex waste liquids. Platinum and palladium are recovered by activated carbon adsorption purification. The adsorbed electrolyte is not contaminated and can be reused in the electrolysis system, which meets the requirements of sustainable development. The adsorbed carbon after adsorption is rich in platinum and palladium. In the subsequent platinum and palladium production process, due to the existence of low platinum and palladium leaching efficiency, low direct recovery rate of platinum and palladium in carbon powder particles, and repeated labor of personnel, the present invention provides a method for recovering platinum and palladium from silver electrolyte, thereby improving the grade of raw materials and solving the problems of low leaching efficiency, high platinum and palladium content in slag phase, and low direct recovery rate of platinum and palladium in the subsequent platinum and palladium production process. At the same time, the operation is simple, which is more in line with existing production and reduces labor repetition. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for recovering platinum and palladium from a silver electrolyte.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0007] (1) Pre-treating the activated carbon by soaking it in water and nitric acid solution respectively;

[0008] (2) placing the pretreated activated carbon into a silver electrolyte containing platinum and palladium ions for adsorption;

[0009] (3) mixing the adsorbed activated carbon and flour evenly to form a flour-activated carbon adhesive;

[0010] (4) burning the flour-activated carbon adhesive to obtain a platinum-palladium raw material;

[0011] (5) Leaching the platinum-palladium raw material.

[0012] As a preferred embodiment of the present invention, the silver electrolyte containing platinum palladium ions comprises Ag, Cu, Pd, Pt and HNO 3 .

[0013] As a preferred embodiment of the present invention, in the step (1), the temperature of the water is above 60°C, and the time for soaking the activated carbon in water is 10-30 minutes; the concentration of the nitric acid solution is 36%, and the time for soaking the activated carbon in the nitric acid solution is 30 minutes to 1 hour.

[0014] As a preferred embodiment of the present invention, in the step (2), the pretreated activated carbon is placed in a silver electrolyte containing platinum and palladium ions for cyclic adsorption.

[0015] As a preferred embodiment of the present invention, the mass ratio of the activated carbon after adsorption to the flour is (2-6):1.

[0016] When the mass ratio of activated carbon to flour is greater than 8:1, the incineration effect is poor and the platinum and palladium leaching rate is low. When the mass ratio of activated carbon to flour is less than 1:1, the proportion of flour combustion products after incineration is relatively large, affecting the grade of raw materials.

[0017] As a preferred embodiment of the present invention, the incineration specifically comprises: incinerating the flour-activated carbon adhesive at 300°C for 2 to 4 hours, then incinerating at 100°C for 5 to 8 hours, and finally incinerating at 200°C for 1 hour.

[0018] The present invention adopts a staged calcination method to remove residual flour, activated carbon and volatile substances adsorbed by the electrolyte, thereby promoting further stabilization of the internal structure of the platinum-palladium raw material; and can effectively improve the activity of the material, which is conducive to the leaching of platinum-palladium ions.

[0019] As a preferred embodiment of the present invention, in step (5), the leaching specifically comprises: placing the platinum-palladium raw material in hydrochloric acid or sulfuric acid, adding a strong oxidant such as hypochlorous acid at 60-100° C. for leaching, and oxidizing the precious metals such as platinum and palladium and the valuable metals such as copper, lead, and bismuth in the platinum-palladium raw material into the solution.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses activated carbon to adsorb platinum and palladium metals in the silver electrolyte, and then mixes and calcines them with flour, thereby improving the grade of the platinum and palladium raw materials, greatly improving the leaching rate and direct recovery rate in the subsequent platinum and palladium production process, and reducing the platinum and palladium content in the slag phase. At the same time, the operation is simple and the labor repetition rate is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of recovering platinum and palladium from silver electrolyte. DETAILED DESCRIPTION

[0022] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0023] Example 1

[0024] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0025] (1) The activated carbon is washed with produced water above 60° C. for 20 min. After washing, the activated carbon is soaked in 36% nitric acid for about 45 min.

[0026] (2) After the adsorption tank is covered with filter cloth, a layer of pre-treated activated carbon with a thickness of 8 cm is laid, and the circulation system of the silver electrolyte is turned on, so that the silver electrolyte (the composition is shown in Table 1) is circulated and adsorbed in the adsorption tank until the adsorption is completed, and then the liquid inlet valve is closed, and the filter bag and the activated carbon are filtered and dried at the same time.

[0027] (3) The adsorbed activated carbon and flour are mixed in a mass ratio of 1:4, and after stirring to form a flour-activated carbon adhesive.

[0028] (4) The flour-activated carbon adhesive was placed in an incinerator, and the heating device was turned on to incinerate the flour-activated carbon adhesive at 300° C. for 1 h, then at 100° C. for 6 h, and finally at 200° C. for 1 h to obtain a platinum-palladium raw material. The mass percentages of platinum and palladium in the platinum-palladium raw material are shown in Table 2.

[0029] (5) The platinum-palladium raw material is leached. The platinum-palladium leaching rate and the mass percentage of platinum-palladium in the leached residue are shown in Table 3.

[0030] Table 1

[0031]

[0032] Example 2

[0033] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0034] (1) The activated carbon is washed with production water above 60° C. for 10 min. After washing, the activated carbon is soaked in 36% nitric acid for about 1 h.

[0035] (2) After the adsorption tank is covered with filter cloth, a layer of pre-treated activated carbon with a thickness of 10 cm is laid, and the circulation system of the silver electrolyte is turned on to allow the silver electrolyte (the composition is shown in Table 1) to circulate and adsorb in the adsorption tank until the adsorption is completed. Then, the liquid inlet valve is closed and the filter bag and the activated carbon are filtered and dried at the same time.

[0036] (3) The adsorbed activated carbon and flour are mixed in a mass ratio of 1:5, and after stirring to form a flour-activated carbon adhesive.

[0037] (4) The flour-activated carbon adhesive was placed in an incinerator, and the heating device was turned on to incinerate the flour-activated carbon adhesive at 300°C for 2 hours, then at 100°C for 5 hours, and finally at 200°C for 1 hour to obtain a platinum-palladium raw material. The mass percentages of platinum and palladium in the platinum-palladium raw material are shown in Table 2.

[0038] (5) The platinum-palladium raw material is leached. The platinum-palladium leaching rate and the mass percentage of platinum-palladium in the leached residue are shown in Table 3.

[0039] Example 3

[0040] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0041] (1) The activated carbon is washed with produced water above 60° C. for 30 minutes. After washing, the activated carbon is soaked in 36% nitric acid for about 30 minutes.

[0042] (2) After the adsorption tank is covered with filter cloth, a layer of pre-treated activated carbon with a thickness of 5 cm is laid, and the circulation system of the silver electrolyte is turned on, so that the silver electrolyte (the composition is shown in Table 1) is circulated and adsorbed in the adsorption tank until the adsorption is completed, and then the liquid inlet valve is closed, and the filter bag and the activated carbon are filtered and dried at the same time.

[0043] (3) The adsorbed activated carbon and flour are mixed in a mass ratio of 1:3, and after stirring to form a dough, a flour-activated carbon adhesive is formed.

[0044] (4) The flour-activated carbon adhesive was placed in an incinerator, and the heating device was turned on to incinerate the flour-activated carbon adhesive at 300° C. for 1.5 h, then at 100° C. for 8 h, and finally at 200° C. for 1 h to obtain a platinum-palladium raw material. The mass percentages of platinum and palladium in the platinum-palladium raw material are shown in Table 2.

[0045] (5) The platinum-palladium raw material is leached. The platinum-palladium leaching rate and the mass percentage of platinum-palladium in the leached residue are shown in Table 3.

[0046] Comparative Example 1

[0047] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0048] (1) The activated carbon is washed with produced water above 60° C. for 20 min. After washing, the activated carbon is soaked in 36% nitric acid for about 45 min.

[0049] (2) After the adsorption tank is covered with filter cloth, a layer of pre-treated activated carbon with a thickness of 8 cm is laid, and the circulation system of the silver electrolyte is turned on, so that the silver electrolyte (the composition is shown in Table 1) is circulated and adsorbed in the adsorption tank until the adsorption is completed, and then the liquid inlet valve is closed, and the filter bag and the activated carbon are filtered and dried at the same time.

[0050] (3) The activated carbon after adsorption is put into an incinerator, and the heating device is turned on to burn the activated carbon at 300° C. for 1 hour, then at 100° C. for 6 hours, and finally at 200° C. for 1 hour to obtain a platinum-palladium raw material. The mass percentages of platinum and palladium in the platinum-palladium raw material are shown in Table 2.

[0051] (5) The platinum-palladium raw material is leached. The platinum-palladium leaching rate and the mass percentage of platinum-palladium in the leached residue are shown in Table 3.

[0052] Comparative Example 2

[0053] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0054] (1) The activated carbon is washed with produced water above 60° C. for 20 min. After washing, the activated carbon is soaked in 36% nitric acid for about 45 min.

[0055] (2) After the adsorption tank is covered with filter cloth, a layer of pre-treated activated carbon with a thickness of 8 cm is laid, and the circulation system of the silver electrolyte is turned on, so that the silver electrolyte (the composition is shown in Table 1) is circulated and adsorbed in the adsorption tank until the adsorption is completed, and then the liquid inlet valve is closed, and the filter bag and the activated carbon are filtered and dried at the same time.

[0056] (3) The adsorbed activated carbon and modified starch are mixed in a mass ratio of 1:4, and after stirring and forming agglomerates, a modified starch-activated carbon adhesive is formed.

[0057] (4) The modified starch-activated carbon binder is placed in an incinerator, and the heating device is turned on to incinerate the modified starch-activated carbon binder at 300°C for 1 hour, then at 100°C for 6 hours, and finally at 200°C for 1 hour to obtain a platinum-palladium raw material. The mass percentages of platinum and palladium in the platinum-palladium raw material are shown in Table 2.

[0058] (5) The platinum-palladium raw material is leached. The platinum-palladium leaching rate and the mass percentage of platinum-palladium in the leached residue are shown in Table 3.

[0059] Comparative Example 3

[0060] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0061] (1) The activated carbon is washed with produced water above 60° C. for 20 min. After washing, the activated carbon is soaked in 36% nitric acid for about 45 min.

[0062] (2) After the adsorption tank is covered with filter cloth, a layer of pre-treated activated carbon with a thickness of 8 cm is laid, and the circulation system of the silver electrolyte is turned on, so that the silver electrolyte (the composition is shown in Table 1) is circulated and adsorbed in the adsorption tank until the adsorption is completed, and then the liquid inlet valve is closed, and the filter bag and the activated carbon are filtered and dried at the same time.

[0063] (3) The adsorbed activated carbon and flour are mixed in a mass ratio of 1:4, and after stirring to form a flour-activated carbon adhesive.

[0064] (4) The flour-activated carbon adhesive was placed in an incinerator, and the heating device was turned on to incinerate the flour-activated carbon adhesive at 300° C. for 8 h to obtain a platinum-palladium raw material. The mass percentages of platinum and palladium in the platinum-palladium raw material are shown in Table 2.

[0065] (5) The platinum-palladium raw material is leached. The platinum-palladium leaching rate and the mass percentage of platinum-palladium in the leached residue are shown in Table 3.

[0066] Comparative Example 4

[0067] A method for recovering platinum and palladium from a silver electrolyte comprises the following steps:

[0068] (1) The activated carbon is washed with produced water above 60° C. for 20 min. After washing, the activated carbon is soaked in 36% nitric acid for about 45 min.

[0069] (2) After the adsorption tank was covered with filter cloth, a layer of pretreated activated carbon with a thickness of 8 cm was laid, and the circulation system of the silver electrolyte was turned on to allow the silver electrolyte (the composition is shown in Table 1) to circulate and adsorb in the adsorption tank until the adsorption was completed. Then, the liquid inlet valve was closed, and the filter bag and the activated carbon were filtered out to obtain the activated carbon after adsorption. The mass percentages of platinum and palladium in the activated carbon after adsorption are shown in Table 2.

[0070] (3) The activated carbon after adsorption was leached. The platinum and palladium leaching rate and the mass percentage of platinum and palladium in the leached residue are shown in Table 3.

[0071] Table 2

[0072] platinum / % palladium / % Example 1 0.13 5.29 Example 2 0.15 4.98 Example 3 0.19 8.32 Comparative Example 1 0.13 4.16 Comparative Example 2 0.13 4.09 Comparative Example 3 0.47 10.16 Comparative Example 4 0.08 2.88

[0073] Table 3

[0074]

[0075] In Comparative Example 3, since a large amount of silver-palladium alloy exists in the platinum-palladium raw material after calcination, metals such as platinum and palladium cannot be leached out.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for recovering platinum and palladium from a silver electrolyte, characterized in that: The steps include: (1) Pre-treating the activated carbon by soaking it in water and nitric acid solution respectively; (2) placing the pretreated activated carbon into a silver electrolyte containing platinum and palladium ions for adsorption; (3) mixing the adsorbed activated carbon and flour evenly to form a flour-activated carbon adhesive; (4) burning the flour-activated carbon adhesive to obtain a platinum-palladium raw material; (5) Leaching the platinum-palladium raw material.

2. The method for recovering platinum and palladium from silver electrolyte according to claim 1, characterized in that: The silver electrolyte containing platinum-palladium ions comprises Ag, Cu, Pd, Pt and HNO3.

3. The method for recovering platinum and palladium from silver electrolyte as claimed in claim 1, characterized in that: In the step (1), the temperature of the water is above 60° C., and the time for soaking the activated carbon in the water is 10-30 minutes; the mass concentration of nitric acid in the nitric acid solution is 36%, and the time for soaking the activated carbon in the nitric acid solution is 30 minutes to 1 hour.

4. The method for recovering platinum and palladium from silver electrolyte as claimed in claim 1, characterized in that: The mass ratio of the activated carbon after adsorption to the flour is (2-6):

1.

5. The method for recovering platinum and palladium from silver electrolyte as claimed in claim 1, characterized in that: The incineration specifically includes: incinerating the flour-activated carbon adhesive at 300° C. for 2 to 4 hours, then incinerating at 100° C. for 5 to 8 hours, and finally incinerating at 200° C. for 1 hour and then cooling naturally.

6. The method for recovering platinum and palladium from silver electrolyte as claimed in claim 1, characterized in that: In the step (5), the leaching specifically comprises: placing the platinum-palladium raw material in hydrochloric acid or sulfuric acid, and then adding a strong oxidant at 60-100° C. for leaching.

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