Method for dissolving silver in waste catalyst based on cavitation effect and green reagent

Abstract

The invention relates to the technical field of dissolution of silver in a waste catalyst, in particular to a method for dissolving silver in a waste catalyst based on a cavitation effect and a green reagent and a preparation method thereof.The method comprises the following steps that firstly, the waste catalyst containing silver is pretreated, the pretreated waste catalyst is mixed with citric acid monohydrate and hydrogen peroxide, and a mixed solution is obtained; a mixed solution is obtained; then, carrying out heating oscillation treatment on the mixed solution to obtain a reacted solution; and finally, carrying out solid-liquid separation on the reacted solution, and after the separation is completed, drying solid residues to constant weight to obtain waste catalyst residues. According to the method for dissolving the silver in the waste catalyst based on the cavitation effect and the green reagent, the silver in the waste catalyst is dissolved through the citric acid monohydrate and the hydrogen peroxide, and compared with some traditional strong acid, strong oxide and other reagents, the brought environmental harm is smaller, and the method is more environmentally friendly.

Description

Technical Field

[0001] This application relates to the technical field of silver dissolution from waste catalysts, and particularly to a method for dissolving silver in waste catalysts based on cavitation effect and green reagents. Background Art

[0002] With the rapid development of industry and social economy, the demand for silver-containing catalysts is increasing continuously, generating a large amount of silver-containing waste catalysts. As an important secondary resource, silver-containing waste catalysts have a relatively high silver content and relatively simple components. It is urgent to recover them efficiently to ensure national strategic resource security and meet the requirements of the national green development strategy. Industrially, silver is leached from silver-containing waste catalysts by generally using strong acid solutions to convert elemental silver into silver ions. Currently, waste catalysts with a relatively high silver content are usually dissolved by nitric acid, and this method has a relatively high leaching rate. However, nitrogen oxides are easily generated during the leaching process, which may cause environmental pollution.

[0003] Although green and environmentally friendly leaching technologies (such as bioleaching, organic acid leaching, or mild oxidation systems) show environmental friendliness advantages in the field of silver recovery from waste catalysts, their practical applications are still limited by relatively low leaching efficiency. For example, when leaching with a thiosulfate-ethylenediaminetetraacetic acid (EDTA) system, the silver leaching rate is usually only 40-60%, far lower than that of the traditional cyanidation method (>95%). Therefore, it is necessary to develop a green and environmentally friendly method with high dissolution efficiency. Summary of the Invention

[0004] The embodiments of this application provide a method for dissolving silver in waste catalysts based on cavitation effect and green reagents. By dissolving silver in waste catalysts with citric acid monohydrate and hydrogen peroxide, compared with some traditional reagents such as strong acids and strong oxidants, it brings less environmental harm and is more green and environmentally friendly.

[0005] To solve the above technical problems, the embodiments of this application provide a method for dissolving silver in waste catalysts based on cavitation effect and green reagents, including the following steps: First, pretreat the silver-containing waste catalyst, and mix the pretreated waste catalyst with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution; then, heat and shake the mixed solution to obtain a reacted solution; finally, perform solid-liquid separation on the reacted solution. After the separation is completed, dry the solid residue to a constant weight to obtain the waste catalyst residue.

[0006] In some exemplary embodiments, after obtaining the waste catalyst residue, the above method further includes: analyzing and measuring the silver content in the waste catalyst residue, and calculating the silver leaching efficiency.

[0007] In some exemplary embodiments, the silver content in the waste catalyst residue is analyzed and measured, and the leaching efficiency of silver is calculated, including: measuring the silver content in the waste catalyst residue by X-ray fluorescence spectrometry to obtain the measurement result; calculating the leaching efficiency of silver using formula (1) according to the measurement result;

[0008]

[0009] where m 渣 is the mass of the residue after leaching; w 渣 is the mass fraction of silver in the residue after leaching; m 料 is the mass of the catalyst before leaching; w 料 is the mass fraction of silver in the catalyst before leaching.

[0010] In some exemplary embodiments, the silver-containing waste catalyst is pretreated, including: putting the silver-containing waste catalyst into an ultrasonic cleaner for cleaning to remove the dust on the surface of the waste catalyst, and putting the ultrasonically cleaned waste catalyst into a blast drying oven for drying at a constant temperature of 100 °C; wherein, the ultrasonic temperature is 30 °C and the ultrasonic power is 150 W; putting the dried waste catalyst into a crusher for crushing; the power of the crusher is 15 KW and the crushing time is 30 minutes.

[0011] In some exemplary embodiments, the pretreated waste catalyst is mixed with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution, including: mixing citric acid monohydrate and hydrogen peroxide to obtain a mixed aqueous solution; mixing the pretreated waste catalyst with the mixed aqueous solution to obtain a mixed solution; in the mixed aqueous solution, the concentration of citric acid monohydrate is 0.5 - 2.5 mol / L; the hydrogen peroxide is 30% hydrogen peroxide and the concentration is 187.5 - 437.5 ml / L.

[0012] In some exemplary embodiments, the concentration of citric acid monohydrate is 1 mol / L; the dosage of 30% hydrogen peroxide is 375 ml / L.

[0013] In some exemplary embodiments, the mixed solution is subjected to heating and shaking treatment to obtain a reacted solution, including: putting the reaction vessel containing the mixed solution of the waste catalyst into an industrial ultrasonic washing tank for dissolving silver in the waste catalyst while heating and shaking for washing; the heating temperature is 30 °C - 70 °C and the shaking time is 0.5 h - 3.0 h.

[0014] In some exemplary embodiments, the heating temperature is 60 °C; the shaking time is 2.5 h.

[0015] In some exemplary embodiments, the reacted solution is subjected to solid-liquid separation. After the separation is completed, the solid residue is dried to a constant weight to obtain the waste catalyst residue, including: using a vacuum filtration device to perform solid-liquid separation on the reacted solution; after the separation is completed, all the waste catalyst residues after filtration are placed in a forced air drying oven and dried to a constant weight.

[0016] In some exemplary embodiments, the drying temperature is 110 °C and the drying time is 6 hours.

[0017] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0018] The embodiments of the present application provide a method for dissolving silver in waste catalysts based on cavitation effect and green reagents, including the following steps: First, the silver-containing waste catalyst is pretreated, and the pretreated waste catalyst is mixed with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution; then, the mixed solution is subjected to heating and shaking treatment to obtain a reacted solution; finally, the reacted solution is subjected to solid-liquid separation, and after the separation is completed, the solid residue is dried to a constant weight to obtain the waste catalyst residue.

[0019] On the one hand, in the method provided by the present application, by introducing additives of citric acid monohydrate and hydrogen peroxide, silver in the waste catalyst is dissolved. Citric acid monohydrate is a green organic acid and does not dissolve silver itself. However, after adding hydrogen peroxide, under acidic conditions, hydrogen peroxide can decompose into atomic oxygen, which has strong oxidation ability and makes up for the defect that citric acid monohydrate cannot dissolve silver. At the same time, this type of green reagent used in the present application causes less environmental harm and is more environmentally friendly compared to some traditional strong acids, strong oxidants and other reagents.

[0020] On the other hand, in addition to using green reagents, the present application also introduces ultrasonic treatment. High-frequency pressure waves are generated in the liquid by ultrasonic waves, forming microbubbles that collapse instantaneously, generating local high temperature, high pressure and microjets, which are beneficial to breaking the carrier on the surface of the waste catalyst, exposing the metal sites, and facilitating the contact between the leaching agent and the metal, thus facilitating the dissolution of the metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] One or more embodiments are illustrated by way of example in the accompanying drawings, and these exemplary illustrations do not limit the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a proportional limitation.

[0022] Figure 1 It is a schematic flow chart of a method for dissolving silver in waste catalysts based on cavitation effect and green reagents provided by an embodiment of the present application.

[0023] Figure 2Schematic flow chart of a method for dissolving silver in waste catalysts based on cavitation effect and green reagents provided by another embodiment of the present application. Detailed implementation manners

[0024] As can be seen from the background art, traditional methods for dissolving silver from waste catalysts usually face a dilemma: if strong oxidizing acids (such as nitric acid) or cyanide systems are used, although efficient dissolution can be achieved, nitrogen oxides (NO x ) and hydrogen cyanide (HCN) and other toxic gases will be released, posing significant risks to the environment and operation safety; if an environmentally friendly leaching agent (such as thiosulfate) is used, due to insufficient redox potential or weak complexing ability, the leaching kinetics of silver will be slow and the recovery rate will be significantly reduced.

[0025] To address the above technical problems, the present application provides a method for dissolving silver in waste catalysts based on cavitation effect and green reagents, including the following steps: First, the silver-containing waste catalyst is pretreated, and the pretreated waste catalyst is mixed with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution; then, the mixed solution is heated and shaken to obtain a reacted solution; finally, the reacted solution is subjected to solid-liquid separation. After the separation is completed, the solid residue is dried to a constant weight to obtain the waste catalyst residue. The method for dissolving silver in waste catalysts based on cavitation effect and green reagents provided by the present application dissolves silver in the waste catalyst through citric acid monohydrate and hydrogen peroxide, which brings less environmental harm and is more environmentally friendly compared to some traditional reagents such as strong acids and strong oxidants.

[0026] The following will elaborate on each embodiment of the present application in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in each embodiment of the present application, many technical details are provided to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0027] Refer to Figure 1 , an embodiment of the present application provides a method for dissolving silver in waste catalysts based on cavitation effect and green reagents, including the following steps:

[0028] Step S1: Pretreat the silver-containing waste catalyst, and mix the pretreated waste catalyst with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution.

[0029] Step S2: Heat and shake the mixed solution to obtain a reacted solution.

[0030] Step S3: Perform solid-liquid separation on the reacted solution. After the separation is completed, dry the solid residue to a constant weight to obtain the waste catalyst residue.

[0031] In some embodiments, such as Figure 2 shown, after obtaining the waste catalyst residue in step S3, the above method further includes: step S4, analyzing and measuring the silver content in the waste catalyst residue, and calculating the leaching efficiency of silver.

[0032] In some embodiments, in step S4, analyzing and measuring the silver content in the waste catalyst residue and calculating the leaching efficiency of silver includes: measuring the silver content in the waste catalyst residue by X-ray fluorescence spectroscopy to obtain a measurement result; calculating the leaching efficiency of silver using formula (1) according to the measurement result;

[0033]

[0034] wherein, m 渣 is the mass of the residue after leaching; w 渣 is the mass fraction of silver in the residue after leaching; m 料 is the mass of the catalyst before leaching; w 料 is the mass fraction of silver in the catalyst before leaching.

[0035] In some embodiments, in step S1, pretreating the silver-containing waste catalyst includes: putting the silver-containing waste catalyst into an ultrasonic cleaner for cleaning to remove the dust on the surface of the waste catalyst, and putting the ultrasonically cleaned waste catalyst into a blast drying oven for drying at a constant temperature of 100°C; wherein, the ultrasonic temperature is 30°C and the ultrasonic power is 150W; putting the dried waste catalyst into a crusher for crushing; the power of the crusher is 15KW and the crushing time is 30 minutes.

[0036] In some embodiments, in step S1, mixing the pretreated waste catalyst with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution includes: mixing citric acid monohydrate and hydrogen peroxide to obtain a mixed aqueous solution; mixing the pretreated waste catalyst with the mixed aqueous solution to obtain a mixed solution; in the mixed aqueous solution, the concentration of citric acid monohydrate is 0.5 - 2.5 mol / L; the hydrogen peroxide is 30% hydrogen peroxide with a concentration of 187.5 - 437.5 ml / L.

[0037] In some embodiments, the concentration of citric acid monohydrate is 1 mol / L; the amount of 30% hydrogen peroxide used is 375 ml / L.

[0038] In some embodiments, in step S2, heating and shaking the mixed solution to obtain a reacted solution includes: putting the reaction container containing the mixed solution of the waste catalyst into an industrial ultrasonic washing tank for dissolving silver in the waste catalyst while heating and shaking for washing; the heating temperature is 30°C - 70°C and the shaking time is 0.5h - 3.0h.

[0039] In some embodiments, the heating temperature is 60°C; the shaking time is 2.5h.

[0040] In some embodiments, in step S3, the reacted solution is subjected to solid-liquid separation. After the separation is completed, the solid residue is dried to a constant weight to obtain waste catalyst residue, including: using a vacuum filtration device to perform solid-liquid separation on the reacted solution; after the separation is completed, all the waste catalyst residues after filtration are placed in a forced-air drying oven and dried to a constant weight.

[0041] In some embodiments, the drying temperature is 110 °C and the drying time is 6 hours.

[0042] The following specifically introduces the method for dissolving silver in waste catalyst based on cavitation effect and green reagent provided by the present application through specific embodiments.

[0043] Example 1

[0044] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent includes the following steps:

[0045] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30 °C, ultrasonic power 150 W), and put the waste catalyst after ultrasonic cleaning into a forced-air drying oven and dry it at a constant temperature of 100 °C.

[0046] (2) Put the dried waste catalyst into a powerful crusher for crushing, and the power of the crusher is 15 KW. After crushing for 30 minutes, stop crushing and take a sample for standby.

[0047] (3) Take 100 g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 1 mol / L of citric acid monohydrate and 375 ml / L of 30% hydrogen peroxide.

[0048] (4) Then put the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic washing tank to dissolve the silver in the waste catalyst while heating and shaking for washing. The solution temperature is controlled at 60 °C. After shaking for 2.5 h, take out the reaction vessel.

[0049] (5) Then use a vacuum filtration device to perform solid-liquid separation on the reacted solution. After the filtration is completed, take all the waste catalyst residues after filtration and put them into a forced-air drying oven at 110 °C for 6 hours to dry to a constant weight.

[0050] (6) Take the dried waste catalyst residue for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W residue in the waste catalyst residue. According to the measurement results, calculate the leaching efficiency of silver using the silver leaching rate calculation formula (formula (1)). Calculation result: The silver leaching rate obtained in Example 1 is 99.5%.

[0051] Comparative Example 1

[0052] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0053] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30°C, ultrasonic power 150W), and put the ultrasonically cleaned waste catalyst into a blast drying oven and dry it at a constant temperature of 100°C.

[0054] (2) Put the dried waste catalyst into a powerful crusher for crushing, and the power of the crusher is 15KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0055] (3) Take 100g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 0.5mol / L citric acid monohydrate and 375ml / L of 30% hydrogen peroxide.

[0056] (4) Then put the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic washing tank for dissolving silver in the waste catalyst while heating and shaking for washing. The solution temperature is controlled at 50°C, and after shaking for 2.0h, take out the reaction vessel.

[0057] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After filtration, put all the waste catalyst residues after filtration into a blast drying oven at 110°C and dry them for 6 hours to constant weight.

[0058] (6) Send the dried waste catalyst residues for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W slag in the waste catalyst residues. According to the measurement results, calculate the silver leaching efficiency using the silver leaching rate calculation formula (Formula (1)). Calculation result: The silver leaching rate obtained in Comparative Example 1 is 59.42%.

[0059] Comparative Example 2

[0060] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0061] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30°C, ultrasonic power 150W), and put the ultrasonically cleaned waste catalyst into a blast drying oven and dry it at a constant temperature of 100°C.

[0062] (2) Put the dried waste catalyst into a powerful crusher for crushing, and the power of the crusher is 15KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0063] (3) Take 100 g of pretreated waste catalyst powder and place it into a mixed aqueous solution containing 2.0 mol / L of citric acid monohydrate and 30% hydrogen peroxide with a dosage of 375 ml / L.

[0064] (4) Then place the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic cleaning tank to dissolve silver in the waste catalyst while heating and shaking for washing. Control the solution temperature at 50 °C, and after shaking for 2.0 h, take out the reaction vessel.

[0065] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After the filtration is completed, take all the waste catalyst residues after filtration and place them in a forced-air drying oven at 110 °C for 6 hours to dry to a constant weight.

[0066] (6) Send the dried waste catalyst residues for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W slag in the waste catalyst residues. According to the measurement results, calculate the silver leaching efficiency using the silver leaching rate calculation formula (Formula (1)). Calculation result: The silver leaching rate obtained in Comparative Example 2 is 97.38%.

[0067] Comparative Example 3

[0068] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0069] (1) At room temperature, place the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30 °C, ultrasonic power 150 W). Place the waste catalyst after ultrasonic cleaning into a forced-air drying oven and dry it at a constant temperature of 100 °C.

[0070] (2) Put the dried waste catalyst into a high-strength crusher for crushing, and the power of the crusher is 15 KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0071] (3) Take 100 g of pretreated waste catalyst powder and place it into a mixed aqueous solution containing 2.5 mol / L of citric acid monohydrate and 30% hydrogen peroxide with a dosage of 375 ml / L.

[0072] (4) Then place the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic cleaning tank to dissolve silver in the waste catalyst while heating and shaking for washing. Control the solution temperature at 50 °C, and after shaking for 2.0 h, take out the reaction vessel.

[0073] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After the filtration is completed, take all the waste catalyst residues after filtration and place them in a forced-air drying oven at 110 °C for 6 hours to dry to a constant weight.

[0074] (6) Take the dried waste catalyst residue for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to determine the silver content W residue in the waste catalyst residue. According to the measurement results, calculate the silver leaching efficiency using the silver leaching rate calculation formula (Formula (1)). Calculation result: The silver leaching rate obtained in Comparative Example 3 is 83.38%.

[0075] Comparative Example 4

[0076] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0077] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30 °C, ultrasonic power 150 W), and put the ultrasonically cleaned waste catalyst into a blast drying oven and dry it at a constant temperature of 100 °C.

[0078] (2) Put the dried waste catalyst into a high-strength crusher for crushing, and the power of the crusher is 15 KW. After the machine crushes for 30 minutes, stop crushing and take samples for standby.

[0079] (3) Take 100 g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 1.0 mol / L citric acid monohydrate and 375 ml / L of 30% hydrogen peroxide.

[0080] (4) Then put the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic washing tank to dissolve the silver in the waste catalyst while heating and shaking for washing. Control the solution temperature at 50 °C, take out the reaction vessel after shaking for 2.0 h.

[0081] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After the filtration is completed, put all the waste catalyst residues after filtration into a blast drying oven at 110 °C and dry them to a constant weight for 6 hours.

[0082] (6) Take the dried waste catalyst residue for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to determine the silver content W residue in the waste catalyst residue. According to the measurement results, calculate the silver leaching efficiency using the silver leaching rate calculation formula (Formula (1)). Calculation result: The silver leaching rate obtained in Comparative Example 4 is 96.5%.

[0083] Comparative Example 5

[0084] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0085] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30°C, ultrasonic power 150W). Then put the ultrasonically cleaned waste catalyst into a forced-air drying oven and dry it at a constant temperature of 100°C.

[0086] (2) Put the dried waste catalyst into a powerful crusher for crushing. The power of the crusher is 15KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0087] (3) Take 100g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 1.0 mol / L citric acid monohydrate and 30% hydrogen peroxide with a dosage of 437.5 ml / L.

[0088] (4) Then put the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic washing tank to dissolve the silver in the waste catalyst while heating and shaking for washing. Control the solution temperature at 50°C. After shaking for 2.0 h, take out the reaction vessel.

[0089] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After the filtration is completed, take all the waste catalyst residues after filtration and put them into a forced-air drying oven at 110°C for 6 hours to dry to a constant weight.

[0090] (6) Send the dried waste catalyst residues for sample analysis. Use X-ray fluorescence spectroscopy (XRF) to measure the silver content W slag in the waste catalyst residues. According to the measurement results, use the silver leaching rate calculation formula (Formula (1)) to calculate the silver leaching efficiency. Calculation result: The silver leaching rate obtained in Comparative Example 5 is 91.85%.

[0091] Comparative Example 6

[0092] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0093] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30°C, ultrasonic power 150W). Then put the ultrasonically cleaned waste catalyst into a forced-air drying oven and dry it at a constant temperature of 100°C;

[0094] (2) Put the dried waste catalyst into a powerful crusher for crushing. The power of the crusher is 15KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0095] (3) Take 100g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 1.0 mol / L citric acid monohydrate and 30% hydrogen peroxide with a dosage of 375 ml / L.

[0096] (4) Then place the reaction vessel containing the spent catalyst and the mixed aqueous solution into an industrial ultrasonic cleaning tank to dissolve the silver in the spent catalyst while heating and shaking for washing. Control the solution temperature at 50 °C. After shaking for 0.5 h, take out the reaction vessel.

[0097] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After the filtration is completed, take all the spent catalyst residues after filtration and place them in a blast drying oven at 110 °C for 6 hours to dry to a constant weight.

[0098] (6) Send the dried spent catalyst residues for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W slag in the spent catalyst residues. According to the measurement results, calculate the silver leaching efficiency using the silver leaching rate calculation formula (Formula (1)). Calculation result: The silver leaching rate obtained in Comparative Example 6 is 87.5%.

[0099] Comparative Example 7

[0100] A method for dissolving silver in spent catalysts based on cavitation effect and green reagents, comprising the following steps:

[0101] (1) At room temperature, place the silver-containing spent catalyst into an ultrasonic cleaner for cleaning for 30 minutes to remove the dust on the surface of the spent catalyst (ultrasonic temperature 30 °C, ultrasonic power 150 W). Place the ultrasonically cleaned spent catalyst into a blast drying oven and dry it at a constant temperature of 100 °C.

[0102] (2) Put the dried spent catalyst into a powerful crusher for crushing. The power of the crusher is 15 KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0103] (3) Take 100 g of the pretreated spent catalyst powder and put it into a mixed aqueous solution containing 1.0 mol / L citric acid monohydrate and 30% hydrogen peroxide with a dosage of 375 ml / L.

[0104] (4) Then place the reaction vessel containing the spent catalyst and the mixed aqueous solution into an industrial ultrasonic cleaning tank to dissolve the silver in the spent catalyst while heating and shaking for washing. Control the solution temperature at 50 °C. After shaking for 2.5 h, take out the reaction vessel.

[0105] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After the filtration is completed, take all the spent catalyst residues after filtration and place them in a blast drying oven at 110 °C for 6 hours to dry to a constant weight.

[0106] (6) Send the dried waste catalyst residue for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W residue in the waste catalyst residue. According to the measurement results, use formula (1) to calculate the silver leaching efficiency. Calculation result: The silver leaching rate obtained in Comparative Example 7 is 98.49%.

[0107] Comparative Example 8

[0108] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0109] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30 °C, ultrasonic power 150 W), and put the ultrasonically cleaned waste catalyst into a blast drying oven and dry it at a constant temperature of 100 °C.

[0110] (2) Put the dried waste catalyst into a powerful crusher for crushing, and the power of the crusher is 15 KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0111] (3) Take 100 g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 1.0 mol / L citric acid monohydrate and 30% hydrogen peroxide with a dosage of 375 ml / L.

[0112] (4) Then put the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic washing tank for dissolving silver in the waste catalyst while heating and shaking for washing. Control the solution temperature at 30 °C, and take out the reaction vessel after shaking for 2.0 h.

[0113] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After filtration, put all the waste catalyst residues after filtration into a blast drying oven at 110 °C for 6 hours and dry to constant weight.

[0114] (6) Take the dried waste catalyst residue for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W residue in the waste catalyst residue. According to the measurement results, use the silver leaching rate calculation formula (formula (1)) to calculate the silver leaching efficiency. Calculation result: The silver leaching rate obtained in Comparative Example 8 is 71.28%.

[0115] Comparative Example 9

[0116] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0117] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30°C, ultrasonic power 150W). Then put the ultrasonically cleaned waste catalyst into a forced-air drying oven and dry it at a constant temperature of 100°C.

[0118] (2) Put the dried waste catalyst into a high-strength crusher for crushing. The power of the crusher is 15KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0119] (3) Take 100g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 1.0 mol / L citric acid monohydrate and 30% hydrogen peroxide with a dosage of 375 ml / L.

[0120] (4) Then put the reaction vessel containing the waste catalyst and the mixed aqueous solution into an industrial ultrasonic washing tank to dissolve the silver in the waste catalyst while heating and shaking for washing. Control the solution temperature at 60°C. After shaking for 2.0 h, take out the reaction vessel.

[0121] (5) Then use a vacuum filtration device to separate the solid and liquid of the reacted solution. After filtration, take all the waste catalyst residues after filtration and put them into a forced-air drying oven at 110°C for 6 hours to dry to a constant weight.

[0122] (6) Send the dried waste catalyst residues for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W slag in the waste catalyst residues. According to the measurement results, use formula (1) to calculate the silver leaching efficiency. Calculation result: The silver leaching rate obtained in Comparative Example 9 is 97.39%.

[0123] Comparative Example 10

[0124] A method for dissolving silver in waste catalyst based on cavitation effect and green reagent, comprising the following steps:

[0125] (1) At room temperature, put the silver-containing waste catalyst into an ultrasonic cleaner and clean it for 30 minutes to remove the dust on the surface of the waste catalyst (ultrasonic temperature 30°C, ultrasonic power 150W). Then put the ultrasonically cleaned waste catalyst into a forced-air drying oven and dry it at a constant temperature of 100°C.

[0126] (2) Put the dried waste catalyst into a high-strength crusher for crushing. The power of the crusher is 15KW. After crushing for 30 minutes, stop crushing and take samples for standby.

[0127] (3) Take 100g of the pretreated waste catalyst powder and put it into a mixed aqueous solution containing 1.0 mol / L citric acid monohydrate and 30% hydrogen peroxide with a dosage of 375 ml / L.

[0128] (4) Then, place the reaction vessel containing the spent catalyst and the mixed aqueous solution into an industrial ultrasonic cleaning tank to dissolve the silver in the spent catalyst while heating and shaking for washing. Control the solution temperature at 70 °C, take out the reaction vessel after shaking for 2.0 h.

[0129] (5) Then, use a vacuum filtration device to separate the solid and liquid of the reacted solution. After the filtration is completed, put all the spent catalyst residues after filtration into a blast drying oven at 110 °C and dry for 6 hours until constant weight.

[0130] (6) Take the dried spent catalyst residues for sample analysis, and use X-ray fluorescence spectroscopy (XRF) to measure the silver content W slag in the spent catalyst residues. According to the measurement results, calculate the silver leaching efficiency using the silver leaching rate calculation formula (Formula (1)). Calculation result: The silver leaching rate obtained in Comparative Example 10 is 88.74%.

[0131] The test calculation data of the silver leaching rates obtained in Example 1 of the present invention and Comparative Examples 1 to 10 are shown in Table 1.

[0132] Table 1 Comparison of calculation results between examples and comparative examples

[0133] Test item Silver leaching rate / % Example 1 99.5 Comparative Example 1 59.42 Comparative Example 2 97.38 Comparative Example 3 83.38 Comparative Example 4 96.50 Comparative Example 5 91.85 Comparative Example 6 87.50 Comparative Example 7 98.49 Comparative Example 8 71.28 Comparative Example 9 97.39 Comparative Example 10 88.74

[0134] It can be seen from Table 1 that: The method for dissolving silver in spent catalysts based on cavitation effect and green reagents provided in this application can dissolve silver in spent catalysts well, and the silver leaching rate is as high as 99.5%. In order to test the influence of experimental conditions on the silver leaching rate, a series of comparative examples are compared in this application. The silver leaching rate test data obtained in Example 1 of the present invention and Comparative Examples 1 to 10 are tested by an inductively coupled plasma emission spectrometer. The test results show that the silver leaching rates in Example 1, Comparative Example 2, Comparative Example 4, Comparative Example 7, and Comparative Example 9 are high, while the silver leaching rates in Comparative Example 1, Comparative Example 3, Comparative Example 6, Comparative Example 8, and Comparative Example 10 are low. It can be seen from the results that: When there are fewer carboxyl groups in the solution, there is not strong enough complexation, so the silver leaching rate decreases; the carboxyl groups in the solution are prone to decarboxylation reaction with H2O2 to generate water and peroxy acid, resulting in a decrease in the silver leaching rate; the thermal decomposition of H2O2 leads to a decrease in the oxidation ability of the leaching agent and a decrease in the silver leaching rate. However, when the concentration of citric acid monohydrate increases, the carboxyl groups increase and the complexation becomes stronger, which is beneficial to the leaching of silver; when the concentration of H2O2 increases, the oxidation ability is enhanced, so the silver leaching rate increases; when the leaching temperature increases, it is beneficial to accelerate the reaction of silver and the silver leaching rate will increase; the silver leaching rate increases with the increase of the liquid-solid ratio.

[0135] According to the above technical solution, the embodiment of the present application provides a method for dissolving silver in waste catalysts based on cavitation effect and green reagents, including the following steps: First, pretreat the silver-containing waste catalyst, and mix the pretreated waste catalyst with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution; then, heat and shake the mixed solution to obtain the reacted solution; finally, perform solid-liquid separation on the reacted solution. After the separation is completed, dry the solid residue to constant weight to obtain the waste catalyst residue.

[0136] In the method provided by the present application, on the one hand, by introducing citric acid monohydrate and hydrogen peroxide additives, silver in the waste catalyst is dissolved. Citric acid monohydrate is a green organic acid that itself does not dissolve silver. However, after adding hydrogen peroxide, under acidic conditions, hydrogen peroxide can decompose into atomic oxygen, which has strong oxidation ability and makes up for the defect that citric acid monohydrate cannot dissolve silver. At the same time, compared with some traditional reagents such as strong acids and strong oxidants, the reagents used in the present application cause less environmental harm and are more environmentally friendly.

[0137] On the other hand, in addition to using green reagents, the present application also introduces ultrasonic treatment. By generating high-frequency pressure waves in the liquid through ultrasonic waves, tiny bubbles are formed and instantaneously collapse, locally generating high temperature, high pressure and micro-jet flow, which is beneficial to breaking the carrier on the surface of the waste catalyst, exposing the metal sites, and facilitating the contact between the leaching agent and the metal, which is beneficial to the dissolution of the metal.

[0138] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present application. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make their own changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A method for dissolving silver in waste catalysts based on cavitation effect and green reagent, characterized in that, It includes the following steps: Pretreat the silver-containing waste catalyst, and mix the pretreated waste catalyst with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution; Perform heat oscillation treatment on the mixed solution to obtain the reacted solution; Perform solid-liquid separation on the reacted solution. After the separation is completed, dry the solid residue to a constant weight to obtain the waste catalyst residue.

2. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 1, wherein After obtaining the waste catalyst residue, the method further includes: Analyze and determine the silver content in the waste catalyst residue, and calculate the silver leaching efficiency.

3. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 2, characterized in that Analyze and determine the silver content in the waste catalyst residue, and calculate the silver leaching efficiency, including: Use X-ray fluorescence spectroscopy to determine the silver content in the waste catalyst residue to obtain the determination result; According to the determination result, calculate the silver leaching efficiency using formula (1); where m 渣 is the mass of the residue after leaching; w 渣 is the mass fraction of silver in the residue after leaching; m 料 is the mass of the catalyst before leaching; w 料 is the mass fraction of silver in the catalyst before leaching.

4. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 1, characterized in that, Pretreat the silver-containing waste catalyst, including: Put the silver-containing waste catalyst into an ultrasonic cleaner to remove the dust on the surface of the waste catalyst, and put the ultrasonically cleaned waste catalyst into a blast drying oven to dry at a constant temperature of 100°C; wherein, the ultrasonic temperature is 30°C and the ultrasonic power is 150W; Put the dried waste catalyst into a crusher for crushing; the power of the crusher is 15KW and the crushing time is 30 minutes.

5. The method for dissolving silver in waste catalyst based on cavitation effect and green reagent according to claim 1, characterized in that, Mix the pretreated waste catalyst with citric acid monohydrate and hydrogen peroxide to obtain a mixed solution, including: Mix citric acid monohydrate and hydrogen peroxide to obtain a mixed aqueous solution; Mix the pretreated waste catalyst with the mixed aqueous solution to obtain a mixed solution; In the mixed aqueous solution, the concentration of citric acid monohydrate is 0.5 - 2.5 mol / L; the hydrogen peroxide is 30% hydrogen peroxide, and the concentration is 187.5 - 437.5 ml / L.

6. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 5, characterized in that, The concentration of citric acid monohydrate is 1 mol / L; the dosage of 30% hydrogen peroxide is 375 ml / L.

7. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 1, wherein, Perform heat oscillation treatment on the mixed solution to obtain the reacted solution, including: Put the reaction vessel containing the mixed solution of the waste catalyst into an industrial ultrasonic washing tank to dissolve the silver in the waste catalyst while heating and oscillating for washing; the heating temperature is 30°C - 70°C, and the oscillation time is 0.5h - 3.0h.

8. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 7, characterized in that, The heating temperature is 60°C; the oscillation time is 2.5h.

9. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 1, characterized in that, Perform solid-liquid separation on the reacted solution. After the separation is completed, dry the solid residue to a constant weight to obtain the waste catalyst residue, including: Use a vacuum filtration device to perform solid-liquid separation on the reacted solution; after the separation is completed, put all the filtered waste catalyst residues into a blast drying oven and dry to a constant weight.

10. The method for dissolving silver in waste catalysts based on cavitation effect and green reagent according to claim 9, characterized in that, The drying temperature is 110°C and the drying time is 6 hours.

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