A precious metal recovery and refining wastewater recycling process

Abstract

The present invention relates to the technical field of wastewater recycling, and specifically to a precious metal recovery and refining wastewater recycling process, comprising the following steps: selecting a precious metal-containing material, preparing a dissolving solution, and adding the precious metal-containing material and the dissolving solution to a dissolving kettle for stirring, dissolving and reacting to obtain a mixture. The present invention introduces a large number of carboxyl and hydroxyl functional groups on the surface of activated carbon through oxidation treatment to form chemical bonds or complexes, significantly enhancing the activated carbon's adsorption capacity for them, and loading treatment to load the active ingredients in the tetrabutyl titanate ethanol solution and the ammonium tungstate solution onto the activated carbon surface, further increasing the number of active sites on the activated carbon surface and changing the electron cloud distribution on its surface, selectively adsorbing organic impurities and heavy metal ions, reducing the entry of impurities into the recovered hydrochloric acid, and promoting the decomposition and regeneration of hydrochloric acid, reducing the loss of hydrochloric acid, and improving the purity and recovery rate of the recovered hydrochloric acid.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater recycling, and in particular to a process for recycling precious metal recovery and refining wastewater. Background Art

[0002] Due to their unique physical and chemical properties, precious metals have widespread and irreplaceable applications in numerous fields, including electronics, jewelry, and aerospace. However, their resources are scarce, and mining from ores is costly and environmentally intensive. Therefore, recovering precious metals from various precious metal-containing waste materials has gradually become an important method for obtaining precious metals. Currently, hydrometallurgy is widely used in precious metal recovery, often using strong acids such as hydrochloric acid as solvents to dissolve precious metal-containing materials for subsequent extraction. However, this method produces large amounts of wastewater containing precious metal ions and residual hydrochloric acid.

[0003] In the prior art, in the existing precious metal recovery and refining process, there is a lack of effective methods for recycling the hydrochloric acid remaining after the reaction. At the same time, during the recovery process, the hydrochloric acid is easily contaminated by impurities, resulting in the recovered hydrochloric acid being of low purity and difficult to be reused in industrial production processes such as precious metal recovery.

[0004] Based on this, the present invention provides a precious metal recovery and refining wastewater recycling process. Summary of the Invention

[0005] The purpose of the present invention is to provide a precious metal recovery and refining wastewater recycling process. The present invention achieves efficient precious metal recovery and hydrochloric acid recycling by optimizing the dissolution and evaporation steps, while improving process efficiency and safety.

[0006] To achieve the above object, the present invention provides the following technical solution: a precious metal recovery and refining wastewater recycling process, comprising the following steps:

[0007] S1: Select materials containing precious metals;

[0008] S2: Prepare the dissolving solution for use;

[0009] S3: adding the precious metal-containing material and the dissolving liquid into a dissolving kettle for stirring and dissolving to obtain a mixture;

[0010] S4: placing the mixture into a centrifuge for centrifugal filtration to complete solid-liquid separation;

[0011] S5: The liquid after solid-liquid separation is selected and added into a falling film evaporator for evaporation and condensation treatment. The temperature of the falling film evaporator is set to 60-80°C, the vacuum pressure is 0.08-0.09 MPa, and the evaporation time is 3 hours. At the same time, during the evaporation process, nitrogen is continuously injected at 0.5-2 L / min, and the condensate is collected once 1 hour before evaporation and once 2 hours after evaporation to obtain a concentrated solution and hydrochloric acid.

[0012] The temperature of the falling film evaporator is set to 60-80°C, the vacuum pressure is set to 0.08-0.09MPa, and the evaporation time is 3 hours. During the evaporation process, nitrogen is continuously injected at 0.5-2L / min. The nitrogen can protect the solution from local overheating and avoid oxidation of the components in the solution. Under such conditions, the water and hydrogen chloride in the solution will gradually evaporate. As the evaporation proceeds, the ratio of hydrogen chloride to water changes. During the evaporation process, the condensate in the first hour is collected and condensed to obtain 20% hydrochloric acid, and the condensate in the last 2 hours is collected and condensed to obtain 5% hydrochloric acid, and the remaining part becomes concentrated liquid.

[0013] Furthermore, the dissolving solution is prepared by mixing the following raw materials in weight percentage: 50-70% hydrochloric acid, 10-30% sodium chlorate, 5-20% modified activated carbon and 1-5% hydrogen peroxide;

[0014] The modified activated carbon is prepared by subjecting activated carbon to pretreatment, oxidation treatment, loading treatment and hydrophobic treatment.

[0015] Furthermore, the pretreatment steps of the activated carbon are: selecting high-quality wood activated carbon, crushing and screening it, then adding it to a stainless steel container, adding deionized water and soaking it for 20-24 hours, changing the water 5-8 times during the soaking period, taking it out after soaking and adding it to an oven to dry it at 105°C to constant weight to complete the pretreatment of the activated carbon.

[0016] Furthermore, the activated carbon oxidation treatment step is: adding the pretreated activated carbon into a reactor containing nitric acid solution, stirring and reflux at 90°C for 3-4 hours, after the reaction is completed, rinsing the activated carbon with deionized water 8-10 times and then adding it to an oven and drying it at 110°C for 8-10 hours to complete the oxidation treatment of the activated carbon.

[0017] Furthermore, the loading treatment step of the activated carbon is as follows: soaking the activated carbon after the oxidation treatment in a loading solution, wherein the loading solution is prepared by mixing a tetrabutyl titanate ethanol solution and an ammonium tungstate solution in a mass ratio of 1:1, the concentration of the tetrabutyl titanate ethanol solution is 5%, the concentration of the ammonium tungstate solution is 5%, and the mass ratio of the activated carbon after the oxidation treatment to the loading solution is 1:(4-6). Soaking for 10-12 hours, taking out the soaked activated carbon and placing it in an oven, drying it at 60°C for 4-6 hours, then adding it to a muffle furnace, heating it to 500°C at 5°C / min, and calcining it at 500°C for 4-5 hours to complete the loading treatment of the activated carbon.

[0018] Furthermore, the hydrophobic treatment step of the activated carbon is: adding the loaded activated carbon to a toluene solvent containing a silane coupling agent, placing it in a reactor, stirring and reacting at 80°C for 3-5 hours, filtering through a filter after the reaction, and first washing the activated carbon with pure toluene 2-4 times, and then washing it with deionized water 3-5 times. After washing, adding it to an oven and drying it at 100°C to constant weight to complete the hydrophobic treatment of the activated carbon.

[0019] Furthermore, the mass ratio of the activated carbon to the toluene solvent is 1:(8-10), and the concentration of the silane coupling agent is 3%.

[0020] Furthermore, the concentration of the hydrochloric acid is 30%, and the particle size of the activated carbon after crushing and screening is 2-4 mm.

[0021] Furthermore, the solid-liquid ratio of the activated carbon to the nitric acid solution is 1:8, and the concentration of the nitric acid solution is 8%.

[0022] Furthermore, the temperature of the dissolving kettle in S3 is set to 60-80° C., the stirring speed is 100-300 rpm, and the reaction is continued for 1-2 hours. The speed of the centrifuge in S4 is set to 2000-4000 rpm, and the stirring is continued for 10-30 minutes.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention adds modified activated carbon to the dissolving solution, and pre-treats the activated carbon to expand its pore structure, thereby providing more active sites for the subsequent adsorption process. The oxidation treatment introduces a large number of carboxyl and hydroxyl functional groups on the surface of the activated carbon. These functional groups can chemically react with the precious metal ions and hydrochloric acid molecules in the wastewater to form chemical bonds or complexes, thereby significantly enhancing the adsorption capacity of the activated carbon for them. The loading treatment loads the active ingredients in the tetrabutyl titanate ethanol solution and the ammonium tungstate solution onto the surface of the activated carbon, thereby further increasing the number of active sites on the surface of the activated carbon and changing the electron cloud distribution on its surface, thereby selectively adsorbing organic impurities and heavy metal ions, reducing the entry of impurities into the recovered hydrochloric acid, and promoting the decomposition and regeneration of the hydrochloric acid, thereby reducing the loss of the hydrochloric acid and improving the purity and recovery rate of the recovered hydrochloric acid.

[0025] 2. The present invention makes the surface of the activated carbon hydrophobic by performing a hydrophobic treatment on the activated carbon, and can selectively adsorb organic impurities while reducing the adsorption of water molecules. The selective adsorption ability can more effectively remove organic impurities in the solvent, improve the purity of hydrochloric acid, and at the same time enhance the chemical stability of the activated carbon in the hydrochloric acid environment, reduce the corrosion and loss of the activated carbon in the solvent, and extend its service life.

[0026] 3. The present invention continuously injects nitrogen during the evaporation of the liquid by the falling film evaporator, thereby inhibiting the decomposition of hydrochloric acid into chlorine and hydrogen, reducing the loss of hydrochloric acid, and improving the recovery rate. At the same time, nitrogen, as an inert gas, can prevent oxidation reactions of precious metal ions or organic impurities during the evaporation process, thereby ensuring the purity of the recovered hydrochloric acid. In addition, the solution after filtration and separation by the falling film evaporator is evaporated. Since hydrochloric acid has a certain volatility, during the evaporation process, the hydrochloric acid in the solution will escape in a gaseous form as the solvent evaporates. After condensation and other treatments, the escaped hydrochloric acid gas forms hydrochloric acid solutions with different concentrations, thereby realizing the recovery of hydrochloric acid. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application are described clearly and completely.

[0029] Example 1: A precious metal recovery and refining wastewater recycling process, comprising the following steps:

[0030] S1: Select materials containing precious metals;

[0031] S2: Prepare the dissolving solution for use;

[0032] S3: adding the precious metal-containing material and the dissolving liquid into a dissolving kettle for stirring and dissolving to obtain a mixture;

[0033] S4: placing the mixture into a centrifuge for centrifugal filtration to complete solid-liquid separation;

[0034] S5: The liquid after solid-liquid separation is selected and added into a falling film evaporator for evaporation and condensation treatment. The temperature of the falling film evaporator is set to 60-80°C, the vacuum pressure is 0.08-0.09 MPa, and the evaporation time is 3 hours. At the same time, during the evaporation process, nitrogen is continuously injected at 0.5-2 L / min, and the condensate is collected once 1 hour before evaporation and once 2 hours after evaporation to obtain a concentrated solution and hydrochloric acid.

[0035] The dissolving solution is prepared by mixing the following raw materials in weight percentage: 50% hydrochloric acid, 10% sodium chlorate, 5% modified activated carbon and 1% hydrogen peroxide;

[0036] The modified activated carbon is prepared by subjecting activated carbon to pretreatment, oxidation treatment, loading treatment and hydrophobic treatment.

[0037] The pretreatment steps of activated carbon are as follows: select high-quality wood activated carbon, crush and screen it, then add it to a stainless steel container, add deionized water and soak it for 20 hours, change the water 5 times during the soaking period, take it out after soaking and add it to an oven and dry it at 105°C to constant weight to complete the pretreatment of the activated carbon.

[0038] The oxidation treatment steps of activated carbon are as follows: the pretreated activated carbon is added to a reactor containing nitric acid solution, stirred and refluxed at 90°C for 3 hours. After the reaction is completed, the activated carbon is rinsed with deionized water 8 times and then placed in an oven and dried at 110°C for 8 hours to complete the oxidation treatment of the activated carbon.

[0039] The loading treatment steps of activated carbon are as follows: soaking the activated carbon after oxidation treatment in a loading solution, which is prepared by mixing tetrabutyl titanate ethanol solution and ammonium tungstate solution in a mass ratio of 1:1. The concentration of tetrabutyl titanate ethanol solution is 5%, and the concentration of ammonium tungstate solution is 5%. The mass ratio of the activated carbon after oxidation treatment and the loading solution is 1:4. Soak for 10 hours, take out the soaked activated carbon and place it in an oven, dry it at 60°C for 4 hours, then add it to a muffle furnace, heat it to 500°C at 5°C / min, and calcine it at 500°C for 4 hours to complete the loading treatment of the activated carbon.

[0040] The hydrophobic treatment steps of activated carbon are as follows: adding the loaded activated carbon to a toluene solvent containing a silane coupling agent, placing it in a reactor, stirring and reacting at 80°C for 3 hours, filtering through a filter after the reaction, and washing the activated carbon twice with pure toluene, and then washing it three times with deionized water. After washing, adding it to an oven and drying it at 100°C to constant weight to complete the hydrophobic treatment of the activated carbon.

[0041] The mass ratio of activated carbon to toluene solvent is 1:8, and the concentration of silane coupling agent is 3%.

[0042] The concentration of hydrochloric acid is 30%, and the particle size of the activated carbon after crushing and screening is 2 mm.

[0043] The solid-liquid ratio of activated carbon to nitric acid solution is 1:8, and the concentration of nitric acid solution is 8%.

[0044] The temperature of the dissolving kettle in S3 was set to 60°C, the stirring speed was 100 rpm, and the reaction was continued for 1 hour. The speed of the centrifuge in S4 was set to 2000 rpm, and the stirring was continued for 10 minutes.

[0045] Example 2: A precious metal recovery and refining wastewater recycling process, comprising the following steps:

[0046] S1: Select materials containing precious metals;

[0047] S2: Prepare the dissolving solution for use;

[0048] S3: adding the precious metal-containing material and the dissolving liquid into a dissolving kettle for stirring and dissolving to obtain a mixture;

[0049] S4: placing the mixture into a centrifuge for centrifugal filtration to complete solid-liquid separation;

[0050] S5: The liquid after solid-liquid separation is selected and added into a falling film evaporator for evaporation and condensation treatment. The temperature of the falling film evaporator is set to 60-80°C, the vacuum pressure is 0.08-0.09 MPa, and the evaporation time is 3 hours. At the same time, during the evaporation process, nitrogen is continuously injected at 0.5-2 L / min, and the condensate is collected once 1 hour before evaporation and once 2 hours after evaporation to obtain a concentrated solution and hydrochloric acid.

[0051] The dissolving solution is prepared by mixing the following raw materials in weight percentage: 60% hydrochloric acid, 20% sodium chlorate, 12.5% ​​modified activated carbon and 3% hydrogen peroxide;

[0052] The modified activated carbon is prepared by subjecting activated carbon to pretreatment, oxidation treatment, loading treatment and hydrophobic treatment.

[0053] The pretreatment steps of activated carbon are as follows: select high-quality wood activated carbon, crush and screen it, then add it to a stainless steel container, add deionized water and soak it for 22 hours, change the water 7 times during the soaking period, take it out after soaking and add it to an oven and dry it at 105°C to constant weight to complete the pretreatment of the activated carbon.

[0054] The oxidation treatment steps of activated carbon are as follows: adding the pretreated activated carbon into a reactor containing nitric acid solution, stirring and reflux at 90°C for 3.5 hours. After the reaction is completed, the activated carbon is rinsed with deionized water 9 times and then placed in an oven and dried at 110°C for 9 hours to complete the oxidation treatment of the activated carbon.

[0055] The loading treatment steps of activated carbon are as follows: soaking the activated carbon after oxidation treatment in a loading solution, which is prepared by mixing tetrabutyl titanate ethanol solution and ammonium tungstate solution in a mass ratio of 1:1. The concentration of tetrabutyl titanate ethanol solution is 5%, and the concentration of ammonium tungstate solution is 5%. The mass ratio of the activated carbon after oxidation treatment and the loading solution is 1:5. Soak for 11 hours, take out the soaked activated carbon and place it in an oven, dry it at 60°C for 5 hours, then add it to a muffle furnace, heat it to 500°C at 5°C / min, and calcine it at 500°C for 4.5 hours to complete the loading treatment of the activated carbon.

[0056] The hydrophobic treatment steps of activated carbon are as follows: adding the loaded activated carbon to a toluene solvent containing a silane coupling agent, placing it in a reactor, stirring and reacting at 80°C for 4 hours, filtering through a filter after the reaction, and washing the activated carbon 3 times with pure toluene, and then washing it 4 times with deionized water. After washing, adding it to an oven and drying it at 100°C to constant weight to complete the hydrophobic treatment of the activated carbon.

[0057] The mass ratio of activated carbon to toluene solvent is 1:8, and the concentration of silane coupling agent is 3%.

[0058] The concentration of hydrochloric acid is 30%, and the particle size of the activated carbon after crushing and screening is 3 mm.

[0059] The solid-liquid ratio of activated carbon to nitric acid solution is 1:8, and the concentration of nitric acid solution is 8%.

[0060] The temperature of the dissolving kettle in S3 was set to 70°C, the stirring speed was 200 rpm, and the reaction was continued for 2 hours. The speed of the centrifuge in S4 was set to 3000 rpm, and the stirring was continued for 20 minutes.

[0061] Example 3: A precious metal recovery and refining wastewater recycling process, comprising the following steps:

[0062] S1: Select materials containing precious metals;

[0063] S2: Prepare the dissolving solution for use;

[0064] S3: adding the precious metal-containing material and the dissolving liquid into a dissolving kettle for stirring and dissolving to obtain a mixture;

[0065] S4: placing the mixture into a centrifuge for centrifugal filtration to complete solid-liquid separation;

[0066] S5: The liquid after solid-liquid separation is selected and added into a falling film evaporator for evaporation and condensation treatment. The temperature of the falling film evaporator is set to 60-80°C, the vacuum pressure is 0.08-0.09 MPa, and the evaporation time is 3 hours. At the same time, during the evaporation process, nitrogen is continuously injected at 0.5-2 L / min, and the condensate is collected once 1 hour before evaporation and once 2 hours after evaporation to obtain a concentrated solution and hydrochloric acid.

[0067] The dissolving solution is prepared by mixing the following raw materials in weight percentage: 70% hydrochloric acid, 30% sodium chlorate, 20% modified activated carbon and 5% hydrogen peroxide;

[0068] The modified activated carbon is prepared by subjecting activated carbon to pretreatment, oxidation treatment, loading treatment and hydrophobic treatment.

[0069] The pretreatment steps of activated carbon are as follows: select high-quality wood activated carbon, crush and screen it, then add it to a stainless steel container, add deionized water and soak it for 24 hours, change the water 8 times during the soaking period, take it out after soaking and add it to an oven and dry it at 105°C to constant weight to complete the pretreatment of the activated carbon.

[0070] The oxidation treatment steps of activated carbon are as follows: the pretreated activated carbon is added to a reactor containing nitric acid solution, stirred and refluxed at 90°C for 4 hours. After the reaction is completed, the activated carbon is rinsed with deionized water 10 times and then placed in an oven and dried at 110°C for 10 hours to complete the oxidation treatment of the activated carbon.

[0071] The loading treatment steps of activated carbon are as follows: soaking the activated carbon after oxidation treatment in a loading solution, which is prepared by mixing tetrabutyl titanate ethanol solution and ammonium tungstate solution in a mass ratio of 1:1, the concentration of tetrabutyl titanate ethanol solution is 5%, the concentration of ammonium tungstate solution is 5%, and the mass ratio of the activated carbon after oxidation treatment and the loading solution is 1:6. Soak for 12 hours, take out the soaked activated carbon and place it in an oven, dry it at 60°C for 6 hours, then add it to a muffle furnace, heat it to 500°C at 5°C / min, and calcine it at 500°C for 5 hours to complete the loading treatment of the activated carbon.

[0072] The hydrophobic treatment steps of activated carbon are as follows: adding the loaded activated carbon to a toluene solvent containing a silane coupling agent, placing it in a reactor, stirring and reacting at 80°C for 5 hours, filtering through a filter after the reaction, and washing the activated carbon with pure toluene 4 times, and then washing it with deionized water 5 times. After washing, adding it to an oven and drying it at 100°C to constant weight to complete the hydrophobic treatment of the activated carbon.

[0073] The mass ratio of activated carbon to toluene solvent is 1:10, and the concentration of silane coupling agent is 3%.

[0074] The concentration of hydrochloric acid is 30%, and the particle size of the activated carbon after crushing and screening is 4 mm.

[0075] The solid-liquid ratio of activated carbon to nitric acid solution is 1:8, and the concentration of nitric acid solution is 8%.

[0076] The temperature of the dissolving kettle in S3 was set to 60-80°C, the stirring speed was 300 rpm, and the reaction was continued for 2 hours. The speed of the centrifuge in S4 was set to 4000 rpm, and the stirring was continued for 30 minutes.

[0077] Comparative Example 1: This comparative example differs from Example 1 in that the activated carbon is not modified in this comparative example.

[0078] Comparative Example 2: This comparative example differs from Example 1 in that no modified activated carbon is added in this comparative example.

[0079] Comparative Example 3: This comparative example differs from Example 1 in that no hydrophobic treatment is performed when modifying the activated carbon in this comparative example.

[0080] Performance test: The recovery rate and recovery concentration of hydrochloric acid in wastewater in the recycling process of Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were tested.

[0081] The concentration of hydrochloric acid recovery is tested using the acid-base titration method (GB / T 601-2016);

[0082] The recovery rate of hydrochloric acid was tested by ultra-performance liquid chromatography-tandem mass spectrometry:

[0083] The obtained test data are recorded in the following table:

[0084]

[0085] By comparing and analyzing the relevant data in the table, it can be seen that the recovery rate and recovery concentration of hydrochloric acid in the wastewater treated in Comparative Example 1, Comparative Example 2 and Comparative Example 3 are lower than those in Examples 1, 2 and 3; this shows that by adding modified activated carbon to the dissolving solution, the pretreatment expands the pore structure of the activated carbon, providing more active sites for the subsequent adsorption process, and the oxidation treatment introduces a large number of carboxyl and hydroxyl functional groups on the surface of the activated carbon. These functional groups can react chemically with the precious metal ions and hydrochloric acid molecules in the wastewater to form chemical bonds or complexes, significantly enhancing the adsorption capacity of the activated carbon for them. The loading treatment loads the active ingredients in the tetrabutyl titanate ethanol solution and the ammonium tungstate solution onto the surface of the activated carbon, further increasing the number of active sites on the surface of the activated carbon, and changing the electron cloud distribution on its surface, selectively adsorbing organic impurities and heavy metal ions, and reducing impurities. The activated carbon is treated with hydrophobicity to make its surface hydrophobic, which can selectively adsorb organic impurities and reduce the adsorption of water molecules. The selective adsorption capacity can more effectively remove organic impurities in the dissolved liquid, improve the purity of hydrochloric acid, and enhance the chemical stability of the activated carbon in the hydrochloric acid environment, reduce the corrosion and loss of the activated carbon in the dissolved liquid, and extend its service life. The falling film evaporator is used to continuously inject nitrogen during the evaporation of the liquid, which can inhibit the decomposition of hydrochloric acid into chlorine and hydrogen, reduce the loss of hydrochloric acid, and improve the recovery rate. At the same time, nitrogen, as an inert gas, can prevent the oxidation reaction of precious metal ions or organic impurities during the evaporation process, thereby ensuring the purity of the recovered hydrochloric acid.

[0086] The wastewater treated by the precious metal recovery and refining wastewater recycling process of the present invention has a high hydrochloric acid recovery rate and recovery concentration. This shows that the precious metal recovery and refining wastewater recycling process provided by the present invention has a broader market prospect and is more suitable for promotion.

[0087] Throughout this specification, references to terms such as "one embodiment," "example," and "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0088] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A precious metal recovery and refining wastewater recycling process, characterized by: The following steps are involved: S1: Select materials containing precious metals; S2: Prepare the dissolving solution for use; S3: adding the precious metal-containing material and the dissolving liquid into a dissolving kettle for stirring and dissolving to obtain a mixture; S4: placing the mixture into a centrifuge for centrifugal filtration to complete solid-liquid separation; S5: Select the liquid after solid-liquid separation and add it to a falling film evaporator for evaporation and condensation treatment. The temperature of the falling film evaporator is set to 60-80°C, the vacuum pressure is 0.08-0.09 MPa, and the evaporation time is 3 hours. At the same time, during the evaporation process, nitrogen is continuously injected at 0.5-2 L / min, and the condensate is collected once 1 hour before evaporation and once 2 hours after evaporation to obtain a concentrated solution and hydrochloric acid; The dissolving solution is prepared by mixing the following raw materials in weight percentage: 50-70% hydrochloric acid, 10-30% sodium chlorate, 5-20% modified activated carbon and 1-5% hydrogen peroxide; The modified activated carbon is prepared by subjecting activated carbon to pretreatment, oxidation treatment, loading treatment and hydrophobic treatment; The temperature of the dissolving kettle in S3 is set to 60-80°C, the stirring speed is 100-300 rpm, and the reaction is continued for 1-2 hours; The activated carbon loading treatment step is as follows: immersing the activated carbon after the oxidation treatment in a loading solution, wherein the loading solution is prepared by mixing a tetrabutyl titanate ethanol solution and an ammonium tungstate solution in a mass ratio of 1:1, the concentration of the tetrabutyl titanate ethanol solution is 5%, the concentration of the ammonium tungstate solution is 5%, and the mass ratio of the activated carbon after the oxidation treatment to the loading solution is 1:(4-6). The activated carbon is soaked for 10-12 hours, and the soaked activated carbon is taken out and placed in an oven, dried at 60°C for 4-6 hours, then added to a muffle furnace, heated to 500°C at 5°C / min, and calcined at 500°C for 4-5 hours to complete the loading treatment of the activated carbon.

2. The precious metal recovery and refining wastewater recycling process according to claim 1, characterized in that: The activated carbon pretreatment steps are as follows: selecting high-quality wood activated carbon, crushing and screening it, then adding it to a stainless steel container, adding deionized water and soaking it for 20-24 hours, changing the water 5-8 times during the soaking period, taking it out after soaking and adding it to an oven to dry it at 105°C to constant weight, thereby completing the pretreatment of the activated carbon.

3. The precious metal recovery and refining wastewater recycling process according to claim 1, characterized in that: The activated carbon oxidation treatment step is as follows: adding the pretreated activated carbon into a reactor containing nitric acid solution, stirring and refluxing at 90° C. for 3-4 hours, and after the reaction is completed, washing the activated carbon with deionized water for 8-10 times and then adding it to an oven for drying at 110° C. for 8-10 hours to complete the oxidation treatment of the activated carbon.

4. The precious metal recovery and refining wastewater recycling process according to claim 1, characterized in that: The hydrophobic treatment step of the activated carbon is as follows: adding the loaded activated carbon to a toluene solvent containing a silane coupling agent, placing the loaded activated carbon in a reactor, stirring and reacting at 80° C. for 3-5 hours, filtering through a filter screen after the reaction, washing the activated carbon with pure toluene for 2-4 times, and then washing it with deionized water for 3-5 times. After washing, placing the activated carbon in an oven and drying it at 100° C. to a constant weight to complete the hydrophobic treatment of the activated carbon.

5. The precious metal recovery and refining wastewater recycling process according to claim 4, characterized in that: The mass ratio of the activated carbon to the toluene solvent is 1:(8-10), and the concentration of the silane coupling agent is 3%.

6. The precious metal recovery and refining wastewater recycling process according to claim 2, characterized in that: The concentration of the hydrochloric acid is 30%, and the particle size of the activated carbon after crushing and screening is 2-4 mm.

7. The precious metal recovery and refining wastewater recycling process according to claim 3, characterized in that: The solid-liquid ratio of the activated carbon to the nitric acid solution is 1:8, and the concentration of the nitric acid solution is 8%.

8. The precious metal recovery and refining wastewater recycling process according to claim 1, characterized in that: The centrifuge speed in S4 is set to 2000-4000 rpm, and stirring is performed for 10-30 minutes.

Images