METHOD FOR CLEAN RECOVERY OF PALLADIUM

Abstract

A method for clean recovery of palladium is provided, including the following steps: mixing a palladium-containing material, a Ce.sup.4+-containing acidic solution, and an additive, subjecting a resulting mixture to leaching to obtain a Pd.sup.2+-containing solution, and subjecting the Pd.sup.2+-containing solution to electrolysis to obtain palladium. In the method, the palladium-containing material is subjected to solution leaching with Ce.sup.4+ as an oxidative leaching agent and a chlorine-containing additive. After leaching is complete, a Ce.sup.4+ and Pd.sup.2+-containing leaching liquor is subjected to electrolysis to realize the green regeneration of Ce.sup.4+ and palladium. The method of the present disclosure does not lead to the generation of NOx and waste liquid. The present disclosure can significantly reduce the environmental impact and production cost and has excellent economic benefits and application prospects.

Claims

1. A method for a clean recovery of palladium, comprising: mixing a palladium-containing material, a Ce.sup.4+-containing acidic solution, and an additive to obtain a mixed solution and conducting a leaching reaction on the mixed solution to obtain a Pd.sup.2+-containing solution.

2. The method according to claim 1, wherein the additive comprises chlorine.

3. The method according to claim 1, further comprising: subjecting the Pd.sup.2+-containing solution to an electrolysis, such that palladium from the electrolysis is produced at a cathode and a Ce.sup.4+-containing acidic solution from the electrolysis reusable for the leaching reaction is produced at an anode.

4. The method according to claim 1, wherein a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L.

5. The method according to claim 1, wherein a concentration of chlorine in the mixed solution obtained after the mixing is 0.01 mol/L to 0.5 mol/L.

6. The method according to claim 1, comprising the following steps: (1) mixing the palladium-containing material, a Ce.sup.4+-containing sulfuric acid and/or nitric acid solution, and a chlorine-containing additive to obtain the mixed solution and subjecting the mixed solution to the leaching reaction at a temperature higher than or equal to 40° C. to obtain the Pd.sup.2+-containing solution, wherein a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L and a concentration of chlorine in the mixed solution is 0.01 mol/L to 0.5 mol/L; and (2) subjecting the Pd.sup.2+-containing solution obtained in step (1) to an electrolysis, such that palladium from the electrolysis is produced at a cathode and a Ce.sup.4+-containing acidic solution from the electrolysis reusable for the leaching reaction is produced at an anode.

7. The method according to claim 2, further comprising: subjecting the Pd.sup.2+-containing solution to an electrolysis, such that palladium from the electrolysis is produced at a cathode and a Ce.sup.4+-containing acidic solution from the electrolysis reusable for the leaching reaction is produced at an anode.

8. The method according to claim 2, wherein a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L.

9. The method according to claim 3, wherein a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L.

10. The method according to claim 2, wherein a concentration of the chlorine in the mixed solution obtained after the mixing is 0.01 mol/L to 0.5 mol/L.

11. The method according to claim 3, wherein a concentration of chlorine in the mixed solution obtained after the mixing is 0.01 mol/L to 0.5 mol/L.

12. The method according to claim 4, wherein a concentration of chlorine in the mixed solution obtained after the mixing is 0.01 mol/L to 0.5 mol/L.

13. The method according to claim 2, comprising the following steps: (1) mixing the palladium-containing material, a Ce.sup.4+-containing sulfuric acid and/or nitric acid solution, and a chlorine-containing additive to obtain the mixed solution and subjecting the mixed solution to the leaching reaction at a temperature higher than or equal to 40° C. to obtain the Pd.sup.2+-containing solution, wherein a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L and a concentration of chlorine in the mixed solution is 0.01 mol/L to 0.5 mol/L; and (2) subjecting the Pd.sup.2+-containing solution obtained in step (1) to an electrolysis, such that palladium from the electrolysis is produced at a cathode and a Ce.sup.4+-containing acidic solution from the electrolysis reusable for the leaching reaction is produced at an anode.

14. The method according to claim 3, comprising the following steps: (1) mixing the palladium-containing material, a Ce.sup.4+-containing sulfuric acid and/or nitric acid solution, and a chlorine-containing additive to obtain the mixed solution and subjecting the mixed solution to the leaching reaction at a temperature higher than or equal to 40° C. to obtain the Pd.sup.2+-containing solution, wherein a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L and a concentration of chlorine in the mixed solution is 0.01 mol/L to 0.5 mol/L; and (2) subjecting the Pd.sup.2+-containing solution obtained in step (1) to the electrolysis, such that the palladium from the electrolysis is produced at the cathode and the Ce.sup.4+-containing acidic solution from the electrolysis reusable for the leaching reaction is produced at the anode.

15. The method according to claim 4, comprising the following steps: (1) mixing the palladium-containing material, a Ce.sup.4+-containing sulfuric acid and/or nitric acid solution, and a chlorine-containing additive to obtain the mixed solution and subjecting the mixed solution to the leaching reaction at a temperature higher than or equal to 40° C. to obtain the Pd.sup.2+-containing solution, wherein a concentration of chlorine in the mixed solution is 0.01 mol/L to 0.5 mol/L; and (2) subjecting the Pd.sup.2+-containing solution obtained in step (1) to an electrolysis, such that palladium from the electrolysis is produced at a cathode and a Ce.sup.4+-containing acidic solution from the electrolysis reusable for the leaching reaction is produced at an anode.

16. The method according to claim 5, comprising the following steps: (1) mixing the palladium-containing material, a Ce.sup.4+-containing sulfuric acid and/or nitric acid solution, and a chlorine-containing additive to obtain the mixed solution and subjecting the mixed solution to the leaching reaction at a temperature higher than or equal to 40° C. to obtain the Pd.sup.2+-containing solution, wherein a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L and a concentration of chlorine in the mixed solution is 0.01 mol/L to 0.5 mol/L; and (2) subjecting the Pd.sup.2+-containing solution obtained in step (1) to an electrolysis, such that palladium from the electrolysis is produced at a cathode and a Ce.sup.4+-containing acidic solution from the electrolysis reusable for the leaching reaction is produced at an anode.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] In order to facilitate the understanding of the present disclosure, some examples of the present disclosure are listed below. Those skilled in the art should understand that these examples only help explain the present disclosure and should not be regarded as specific limitations to the present disclosure.

[0029] The technical solutions of the present disclosure will be further described below through specific embodiments.

[0030] In a specific embodiment, the present disclosure provides a method of clean recovery of palladium, including the following steps: [0031] (1) The palladium-containing material, a Ce.sup.4+-containing acidic solution, and a chlorine-containing additive are mixed to obtain a mixed solution, and the mixed solution is subjected to a leaching reaction to obtain a Pd.sup.2+-containing solution, where a concentration of Ce.sup.4+ in the Ce.sup.4+-containing acidic solution is higher than or equal to 0.05 mol/L and a concentration of chloride in the mixed solution is 0.01 mol/L to 0.5 mol/L.

[0032] (2) The Pd.sup.2+-containing solution obtained in step (1) is subjected to electrolysis, such that palladium is produced at a cathode and a Ce.sup.4+-containing acidic solution reusable for leaching is produced at an anode.

[0033] It should be noted that the process provided in the examples of the present disclosure or a replacement or change of conventional data are within the protection scope and disclosure scope of the present disclosure.

Example 1

[0034] In this example, a method for clean recovery of palladium was provided, including the following steps:

[0035] 0.1 g of palladium powder and a specified amount of sodium chloride solid were mixed and ground for 1 min. A Ce.sup.4+-containing sulfuric acid solution was added to make [Cl]=0.04 mol/L and [Ce.sup.4+]=0.05 mol/L in a resulting mixed solution, and a leaching reaction was conducted at 80° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a clear palladium sulfate leaching liquor. As calculated, the palladium leaching rate in this example was 99.8%.

Example 2

[0036] In this example, a method for clean recovery of palladium was provided, including the following steps:

[0037] 0.2 g of palladium powder and a specified amount of lithium chloride solid were mixed and ground for 5 min. A Ce.sup.4+-containing sulfuric acid solution was added to make [Cl]=0.01 mol/L and [Ce.sup.4+]=0.05 mol/L in a resulting mixed solution, and a leaching reaction was conducted at 60° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a clear palladium sulfate leaching liquor. As calculated, the palladium leaching rate in this example was 99.6%.

Example 3

[0038] In this example, a method for clean recovery of palladium was provided, including the following steps:

[0039] 5 g of palladium powder and a specified amount of sodium chloride solid were mixed and ground for 30 min. A nitric acid solution of ceric ammonium nitrate was added to make [Cl]=0.05 mol/L and [Ce.sup.4+]=1 mol/L in a resulting mixed solution, and a leaching reaction was conducted at 40° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a clear palladium nitrate leaching liquor. As calculated, the palladium leaching rate in this example was 99.7%.

Example 4

[0040] In this example, a method for clean recovery of palladium was provided, including the following steps:

[0041] 2.3 g of palladium powder was mixed with a Ce.sup.4+-containing sulfuric acid solution, then a specified amount of sodium chlorate solid was added to make [Cl]=0.05 mol/L and [Ce.sup.4+]=0.5 mol/L in a resulting mixed solution, and a leaching reaction was conducted at 80° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a clear palladium sulfate leaching liquor. As calculated, the palladium leaching rate in this example was 99.8%.

Example 5

[0042] In this example, a method for clean recovery of palladium was provided, including the following steps: [0043] 0.5 g of palladium powder was mixed with a Ce.sup.4+-containing nitric acid solution, then a specified amount of potassium chloride solid was added to make [Cl]=0.27 mol/L and [Ce.sup.4+]=0.1 mol/L in a resulting mixed solution, and a leaching reaction was conducted at 50° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a clear palladium nitrate leaching liquor. As calculated, the palladium leaching rate in this example was 99.2%.

Example 6

[0044] In this example, a method for clean recovery of palladium was provided, including the following steps: [0045] 0.9 g of palladium powder was mixed with a Ce.sup.4+-containing nitric acid solution, then a specified amount of acetyl chloride was added to make [Cl]=0.01 mol/L and [Ce.sup.4+]=0.2 mol/L in a resulting mixed solution, and a leaching reaction was conducted at 60° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a clear palladium nitrate leaching liquor. As calculated, the palladium leaching rate in this example was 99.7%.

Example 7

[0046] In this example, a method for clean recovery of palladium was provided, including the following steps: [0047] 245 mL of a 0.2 mol/L ceric nitrate solution was mixed with 5 mL of 0.5 mol/L hydrochloric acid to obtain a mixed solution with [Cl]=0.01 mol/L and [Ce.sup.4+]=0.196 mol/L, then 2.5 g of palladium powder with a purity of 91% was added, and a leaching reaction was conducted. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a Pd.sup.2+-containing solution. As calculated, the palladium leaching rate in this example was 99.6%. The leaching liquor with Ce.sup.3+ and Pd.sup.2+ was subjected to electrolysis, such that Ce.sup.3+ was oxidized into Ce.sup.4+ (which could be returned for leaching) at an anode and Pd.sup.2+ was reduced into palladium with a purity of 99.5% at a cathode.

Example 8

[0048] In this example, a method for clean recovery of palladium was provided, including the following steps: [0049] A ceric ammonium nitrate-containing sulfuric acid solution was mixed with sodium chloride solid to make [Cl]=0.17 mol/L and [Ce.sup.4+]=1 mol/L in a resulting mixed solution, then 4.6 g of palladium powder was added with a molar ratio of Ce.sup.4+ to Pd being 2.4:1, and a leaching reaction was conducted at 60° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a Pd.sup.2+-containing solution. As calculated, the palladium leaching rate in this example was 99.2%.

Example 9

[0050] In this example, a method for clean recovery of palladium was provided, including the following steps: [0051] A residue obtained after calcination of 100 g of a palladium-carbon catalyst with a palladium content of 50%, 0.7 g of sodium chloride solid, and 10 mL of water were mixed and ground for 5 min, then 800 mL of a 1.5 mol/L Ce.sup.4+-containing nitric acid solution was added to make [Cl]=0.015 mol/L and [Ce.sup.4+]=1.5 mol/L in a resulting mixed solution, and a leaching reaction was conducted at 60° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a Pd.sup.2+-containing solution. As calculated, the palladium leaching rate in this example was 99.4%.

Example 10

[0052] In this example, a method for clean recovery of palladium was provided, including the following steps: [0053] A residue obtained after full calcination of a palladium-carbon catalyst in the air was mixed with a nitric acid solution with a chlorine content of 0.03 mol/L and a Ce.sup.4+ ion content of 1.5 mol/L (where a molar ratio of Ce.sup.4+ to Pd was 2.4:1), and a leaching reaction was conducted at 80° C. The resulting leaching solution was filtered to remove a residual solid and a suspended matter to obtain a Pd.sup.2+-containing solution. As calculated, the palladium leaching rate in this example was 99.5%.

Example 11

[0054] In this example, a method for clean recovery of palladium was provided, including the following steps: [0055] Ceric nitrate, concentrated nitric acid, monochloroacetic acid, and pure water were used to prepare a mixed solution with [Ce.sup.4+]=1.5 mol/L, [H.sup.+]=1 mol/L, and [Cl]=0.5 mol/L. 20 g of palladium powder was added to 100 mL of the mixed solution, and a leaching reaction was conducted at 60° C. The resulting system was filtered to obtain an unreacted palladium powder and a leaching liquor. The mixed solution prepared above was taken and added to the unreacted palladium powder, and a leaching reaction was conducted once again to achieve complete dissolution. As calculated, the palladium leaching rate in this example was 100%.

Example 12

[0056] In this example, a method for clean recovery of palladium was provided, including the following steps: [0057] 10 g of potassium chloride and 1 L of 0.1 mol/L dilute hydrochloric acid were added to 100 g of PdNi.sub.5 alloy fragments, and a resulting mixture was heated to 40° C. or higher to allow activation for 10 min. 10 L of a 0.11 mol/L ceric sulfate solution was added to the mixture, and a thorough leaching reaction was conducted at 60° C. A leaching liquor was subjected to electrolysis, such that Ce.sup.3+ was oxidized into Ce.sup.4+ (which could be returned for leaching) at an anode, and a potential at a cathode was controlled to reduce Pd.sup.2+ into palladium and then reduce Ni.sup.2+ into nickel. As calculated, the palladium leaching rate in this example was 99.5%.

Comparative Example 1

[0058] In this comparative example, a method for clean recovery of palladium was provided, which was the method in Example 1 in the detailed description of CN109592722A, and an extracted palladium nitrate solution was prepared by the method. A large amount of yellow smoke (NOx) was produced during the reaction. Because nitric acid, aqua regia, a NOx tail gas absorber, and the like were used during the reaction, a large amount of waste liquid was produced, causing heavy environmental pollution.

[0059] For the palladium solution or palladium obtained by the method in each of Examples 1 to 12, a leaching rate was calculated as follows:

leaching rate=1−[(palladium concentration in leaching liquor×volume of leaching liquor)/(palladium content in initial material×raw material mass)]×100%.

[0060] Results showed that, in each of Examples 1 to 12, a palladium leaching rate was higher than 99%, no toxic gas was used in the leaching process, and no NOx was produced. Through electrolysis, the mother liquor was recycled without the generation of wastewater.

[0061] In summary, the present disclosure provides a method for clean recovery of palladium, where palladium is leached with a low-cost acidic Ce.sup.4+ solution as an oxidizing agent and chlorine as an additive, which completely eliminates the generation of a nitrogen oxide tail gas in the traditional process and realizes the clean extraction of palladium. A leaching liquor is subjected to electrolysis to realize the regeneration of Ce.sup.4+ and the preparation of palladium. The method of the present disclosure has a high palladium recovery rate, a low production cost, and promising application prospects.

[0062] The above are merely specific implementations of the present disclosure, and the protection scope of the present disclosure is not limited thereto. Any modification or replacement easily conceived by those skilled in the art within the technical scope of the present disclosure should fall within the protection scope of the present disclosure.