Process for the enrichment of precious metals from waste water containing precious metal and activated carbon particles

Abstract

The present application relates to the field of wastewater treatment, and discloses a method for enriching noble metals from wastewater containing noble metals and activated carbon particles and application thereof.The method comprises the following steps: 1) mixing the wastewater with acid to perform acid treatment, to obtain an acid treatment product; 2) performing first filtration treatment on the acid treatment product by using a first filtration medium with a pore size of less than 20 microns, to obtain a first filtration product; and 3) performing second filtration treatment on the first filtration product by using a second filtration medium with a pore size of less than 5 microns, to obtain a second filtration product.The acid treatment makes the particle size of the activated carbon particles in the acid treatment product greater than 20 microns; the first filtration treatment makes the solid content in the first filtration product 2-3 wt.%; and the second filtration treatment makes the solid content in the second filtration product 70-85 wt.%.The method has a simple process, can greatly save treatment time and treatment cost, and realizes high enrichment of noble metals.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wastewater treatment, in particular to a method for enriching noble metals from wastewater containing noble metals and activated carbon particles and application thereof. BACKGROUND

[0002] In the field of catalyst preparation, etc., a large amount of wastewater containing noble metals and activated carbon particles will be produced due to the introduction of noble metals and activated carbon particles, and the noble metals in the wastewater are difficult to recover and enrich, which not only causes waste of resources, but also causes serious pollution to the environment.

[0003] For example, in the preparation process of palladium-carbon catalyst for terephthalic acid hydrogenation refining, a large amount of wastewater containing noble metal palladium will be produced in the reduction and washing process, and the palladium in the wastewater is loaded on activated carbon particles in the form of elemental metal, which is difficult to collect and recover due to its low concentration and small particle size.

[0004] Various recovery and treatment methods have been tried in the art, for example, the wastewater is introduced into a conventional plate and frame filter for pressure filtration treatment after sedimentation to collect the filter cake. However, such method has low enrichment efficiency of noble metals, and the content of noble metals in the filtrate remains at a high concentration level, and the enrichment rate is only about 60 wt%.

[0005] For example, it has also been tried to add a conventional organic flocculant to the wastewater for flocculation, and then pressure filtration by a plate and frame filter, but due to the small particle size of part of the particles in the wastewater, the flocculation effect is poor, and the viscosity of the flocculation product is too large, which will block the pump and pipeline of the filter, and the filter cake formed in the later stage is also difficult to handle. In addition, the use of organic flocculants will also cause problems such as COD exceeding the standard.

[0006] In addition, if the wastewater is directly dried, the required energy consumption and time are too long, and it cannot be applied to the treatment of wastewater in large-scale industrial production.

[0007] In summary, the treatment of wastewater containing noble metals and activated carbon particles is extremely difficult at present, and conventional methods cannot effectively enrich noble metals, and the treated water still contains a high concentration of noble metals, or the economic cost and time cost of treatment are too high, which cannot meet the needs of industrial production. Therefore, it is urgent to develop a metal enrichment method for wastewater containing noble metals and activated carbon particles. SUMMARY

[0008] The present application aims to overcome the problems of the prior art, i.e. difficulty in treating wastewater containing noble metal and activated carbon particles and insufficient enrichment of noble metal, and provides a method for enriching noble metal from wastewater containing noble metal and activated carbon particles, which not only has a simple process, can greatly save treatment time and treatment cost, but also can achieve high enrichment of noble metal while ensuring that the treated water body contains almost no noble metal.

[0009] To achieve the above-mentioned object, the present application provides a method for enriching noble metal from wastewater containing noble metal and activated carbon particles, wherein the noble metal is loaded on the activated carbon particles, and the method comprises the following steps:

[0010] 1) mixing the wastewater with acid for acid treatment to obtain an acid treatment product;

[0011] 2) performing first filtration treatment on the acid treatment product using a first filtration medium with a pore size of 20 μm or less to obtain a first filtration product;

[0012] 3) performing second filtration treatment on the first filtration product using a second filtration medium with a pore size of 5 μm or less to obtain a second filtration product,

[0013] wherein the acid treatment makes the particle size of the activated carbon particles in the acid treatment product greater than 20 μm;

[0014] the first filtration treatment makes the solid content in the first filtration product 2-3% by weight;

[0015] the second filtration treatment makes the solid content in the second filtration product 70-85% by weight.

[0016] Preferably, the content of noble metal in the wastewater is 0.1-2 mg / L, more preferably 0.1-1 mg / L.

[0017] Preferably, the noble metal is one or more of palladium, platinum and gold, more preferably palladium.

[0018] Preferably, the content of activated carbon particles in the wastewater is 2-6 mg / L, more preferably 4-6 mg / L.

[0019] Preferably, the wastewater is wastewater generated in the preparation process of palladium-carbon catalyst; more preferably, the wastewater is wastewater generated during the reduction and washing of palladium-carbon catalyst.

[0020] Preferably, the particle size of the activated carbon particles in the wastewater is greater than 1 μm.

[0021] Preferably, the average particle size of the activated carbon particles is 10-50 μm.

[0022] Preferably, the number of activated carbon particles having a particle size of 5 μm or less accounts for 5-15% of the total number of activated carbon particles.

[0023] Preferably, the pH of the wastewater is 9-10.

[0024] Preferably, in step 1), the acid is selected from one or more of sulfuric acid, hydrochloric acid and nitric acid, and more preferably is hydrochloric acid.

[0025] Preferably, the acid treatment is performed for 2-10 h, and more preferably for 4-6 h.

[0026] Preferably, the pH of the acid treatment product is 6-8, and more preferably is 7-8.

[0027] Preferably, in step 2), the pore size of the first filter medium is 5-20 μm.

[0028] Preferably, in step 2), the pressure of the first filtration treatment is 0.1-0.3 MPa, and more preferably is 0.1-0.2 MPa.

[0029] Preferably, the first filtration treatment results in a solid content of 2.5-3% by weight in the first filtration product.

[0030] Preferably, in step 3), the pore size of the second filter medium is 1-5 μm.

[0031] Preferably, in step 3), the pressure of the second filtration treatment is 0.5 MPa or less, and more preferably is 0.1-0.5 MPa.

[0032] Preferably, the second filtration treatment results in a solid content of 70-80% by weight in the second filtration product.

[0033] Preferably, the method further comprises a step of drying the second filtration product.

[0034] Preferably, the drying treatment comprises air drying and heating drying in sequence.

[0035] Preferably, in the air drying, the air flow rate is 5-15 m 3 / h per 1 kg of the second filtration product, and more preferably is 5-10 m 3 / h.

[0036] Preferably, the conditions of the air drying include a temperature of 20-40 °C, a pressure of 0.1-0.5 MPa, and a time of 10-30 min.

[0037] Preferably, the water content of the product after the air drying is 10-30% by weight, and more preferably is 10-15% by weight.

[0038] Preferably, the heating drying condition comprises: temperature of 50-120℃, time of 24-72h.

[0039] The second aspect of the present application provides an application of the method of the first aspect of the present application in treating wastewater produced by a palladium-carbon catalyst.

[0040] Through the above technical solution, the noble metal in the wastewater can be highly enriched, so that the recovery rate of the noble metal can be as high as 99% or more, and the enrichment time is significantly reduced, the efficiency is greatly improved, and it is very suitable for the recovery and treatment of industrial wastewater.

[0041] In addition, the method provided by the present application does not need to add flocculants and other treatment agents, and only needs to mix the wastewater with acid, so that the small activated carbon particles can grow to more than 20μm, thereby facilitating the subsequent filtration treatment.

[0042] On the other hand, by adding acid, the pH of the wastewater can also be adjusted to a dischargeable level, without the need for subsequent pH adjustment.

[0043] In addition, in the present application, by using a filter medium with a specific pore size for the first filtration treatment and the second filtration treatment, not only can the filtrate produced by filtration not contain noble metals, but also such selection and cooperation can greatly improve the filtration efficiency, so that the solid content in the first filtration product and the second filtration product is greatly improved, thereby facilitating efficient enrichment.

[0044] In addition, by further sequentially performing aeration drying and heating drying on the second filtration product, the drying speed can be significantly improved, and the enrichment efficiency of the noble metal is further improved.

[0045] In the method of the present application, through the organic combination and synergistic effect between each step, the processing flow can be simplified to the greatest extent, the processing cost is greatly reduced, and the noble metal can be highly enriched, which is very suitable for large-scale industrial processing. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a flowchart according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0047] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values should be understood as approximately about the values stated. The endpoints of the ranges of values and the values thereof should be understood as being inclusive of the values between the endpoints. The endpoints of the ranges of values and the values thereof should be understood as being inclusive of the point values themselves. The endpoints of the ranges of values and the values thereof should be understood as being inclusive of the point values themselves. The disclosure of ranges of values are not to be interpreted as being limited to those values and include all values between the end points, inclusive. Values disclosed herein should be understood to be approximate, and any numerical value, including any numerical value disclosed in the Examples, can have associated with it a reasonable range that is around order of magnitude of the stated value or values. Other ranges of values disclosed herein should be interpreted to be inclusive of values outside the stated ranges.

[0048] The present application provides a method for enriching noble metal from waste water containing noble metal and activated carbon particles, the noble metal being loaded on the activated carbon particles, the method comprising the following steps:

[0049] 1) mixing the waste water with acid to perform acid treatment, to obtain an acid treatment product;

[0050] 2) performing first filtration treatment on the acid treatment product using a first filtration medium with a pore size of 20 μm or less, to obtain a first filtration product;

[0051] 3) performing second filtration treatment on the first filtration product using a second filtration medium with a pore size of 5 μm or less, to obtain a second filtration product,

[0052] wherein the acid treatment makes the particle size of the activated carbon particles in the acid treatment product greater than 20 μm;

[0053] the first filtration treatment makes the solid content in the first filtration product 2-3% by weight;

[0054] the second filtration treatment makes the solid content in the second filtration product 70-85% by weight.

[0055] In the present application, it should be understood that the waste water contains noble metal and activated carbon particles, the noble metal being loaded on the activated carbon particles, and due to the adsorption force of activated carbon, the noble metal is in a state of being loaded on the activated carbon particles during the treatment process.

[0056] In the method of the present application, the type of the noble metal is not particularly limited, and can be various noble metals, and preferably, the noble metal exists in the form of an element.

[0057] The noble metal can be one or more of palladium, platinum and gold, and is preferably palladium.

[0058] In the present application, the content of the noble metal in the waste water can vary in a large range, for example, the content of the noble metal in the waste water can be 0.1-2 mg / L, and is preferably 0.1-1 mg / L.

[0059] On the other hand, in the present application, the content of the activated carbon particles can also vary in a large range, for example, the content of the activated carbon particles in the waste water can be 2-6 mg / L, and is more preferably 4-6 mg / L.

[0060] In the present application, the particle size of the activated carbon particles in the waste water is greater than 1 μm.

[0061] In addition, preferably, the average particle size of the activated carbon particles is 10-50 μm.

[0062] In addition, in the wastewater, preferably, the number of activated carbon particles having a particle size of 5 μm or less accounts for 15% or less of the total number of activated carbon particles, more preferably 5-15%.

[0063] In the present application, the wastewater is preferably wastewater generated in the preparation of a palladium-carbon catalyst, more preferably wastewater generated in the reduction and washing in the preparation of a palladium-carbon catalyst, which contains activated carbon particles and palladium loaded on the activated carbon particles.

[0064] In addition, the pH of the wastewater can be alkaline, for example, the pH of the wastewater can be 9 or more, preferably 9-10.

[0065] Hereinafter, the method for enriching noble metal from wastewater containing noble metal and activated carbon particles according to the present application will be described in detail.

[0066] First, in step 1), the wastewater is mixed with an acid for acid treatment to obtain an acid treatment product.

[0067] According to the present application, the wastewater contains activated carbon particles loaded with noble metal, and there can be small particles in the activated carbon. In the subsequent filtration process, the small activated carbon particles will enter the filtrate along with the filter medium, which will cause loss of noble metal on the one hand, and will also pollute the environment after the discharge of the filtrate containing noble metal on the other hand.

[0068] Although the conventional flocculants can achieve flocculation and can aggregate small activated carbon particles, the viscosity of the flocculation product is large, which is not conducive to the subsequent filtration, and the use of organic flocculants and the like will also introduce COD, increasing the burden of subsequent treatment.

[0069] The inventors of the present application have unexpectedly found that by mixing the wastewater with an acid, the particle size of the activated carbon particles in the obtained acid treatment product is greater than 20 μm, thereby reducing the requirement for subsequent filtration, and the viscosity of the obtained acid treatment product is low, which is very conducive to the implementation of subsequent filtration and the like; on the other hand, the wastewater is generally alkaline wastewater, and by adding the acid, the pH of the wastewater can be further adjusted to meet the discharge standard, without the need for additional adjustment.

[0070] In the present application, the acid treatment makes the particle size of the activated carbon particles in the acid treatment product greater than 20 μm, which means that after the acid treatment, the particle size of 99.9% or more of the activated carbon particles in the obtained acid treatment product can be greater than 20 μm.

[0071] In addition, it should be understood that the particle size of the activated carbon particles in the acid treatment product here refers to the particle size of the agglomerated activated carbon particles obtained after acid treatment.

[0072] In the present application, the kind of the acid is not particularly limited, and the acid can be an inorganic acid or an organic acid. In consideration of the fact that the organic acid further introduces organic substances into the waste water, the acid is preferably an inorganic acid.

[0073] The acid can be, for example, one or more of sulfuric acid, hydrochloric acid, and nitric acid, more preferably hydrochloric acid and / or nitric acid, and further preferably hydrochloric acid.

[0074] In addition, in the present application, the acid is preferably used in the form of an aqueous acid solution, and the concentration of the acid in the aqueous acid solution is not particularly limited. For example, the concentration of the acid in the aqueous acid solution can be 5 to 20% by weight, and preferably 10 to 15% by weight.

[0075] By controlling the concentration of the acid within the above range, on the one hand, the effect of the acid treatment can be significantly increased, so that the particle size of the activated carbon particles is greater than 20 μm; on the other hand, the amount of the aqueous acid solution can also be controlled, which helps to reduce the production cost.

[0076] In addition, in the present application, the amount of the acid added is such that the pH of the acid-treated product is 6 to 8, and more preferably 7 to 8.

[0077] In addition, in the present application, the time for the acid treatment is not particularly limited, as long as the acid-treated product can be obtained.

[0078] For example, the time for the acid treatment can be 2 to 10 h, and preferably 4 to 6 h. In this way, the effect of the acid treatment can be further ensured.

[0079] Next, in step 2), the acid-treated product is subjected to a first filtration treatment.

[0080] In the present application, the first filtration treatment can be performed using various filtration devices commonly used in the art, and is not particularly limited. For example, the first filtration treatment can be performed using one or more of a precision filter, a plate-and-frame filter press, and a siphon-type filter.

[0081] In the present application, the first filtration treatment is preferably performed using a precision filter. As such a precision filter, for example, there can be used a precision filter of Model VMTF-10-304-F0PN-G manufactured by Shanghai Weichi Filtration System Co., Ltd.

[0082] In addition, in the present application, the first filtration medium is not particularly limited, and can be, for example, a filter cartridge, a paperboard, a filter cloth, or a filter paper, and is preferably a filter cartridge.

[0083] In addition, in a preferred embodiment of the present application, the first filtration treatment is performed using a precision filter, and a high-molecular polyethylene filter cartridge is used.

[0084] According to the present application, the purpose of the first filtering treatment is to separate part of the water in the acid treatment product and the activated carbon particles loaded with noble metal, and since the particle size of the activated carbon particles in the acid treatment product is greater than 20 μm due to the acid, the pore size of the first filtering medium used in the first filtering treatment is less than 20 μm, and in order to further ensure the filtering efficiency and the enrichment effect of the noble metal, preferably, the pore size of the first filtering medium is preferably 5-20 μm.

[0085] In the present application, the conditions for the first filtering treatment are not particularly limited, and conventional filtering conditions in the art can be used.

[0086] However, the inventors of the present application have found through extensive research that in the first filtering treatment, the pressure parameter of the first filtering treatment is very critical, and excessive pressure can cause the filtering medium to break or cause the occurrence of a blocking phenomenon; insufficient pressure can result in low filtering efficiency and limited separation capacity, which is not conducive to metal enrichment. Therefore, in the present application, preferably, the pressure of the first filtering treatment is 0.1-0.3 MPa, more preferably 0.1-0.2 MPa.

[0087] In the present application, through the first filtering treatment, the solid content in the first filtering product is 2-3 wt%, preferably 2.5-3 wt%. Thus, water and activated carbon particles loaded with noble metal can be separated to the maximum extent during the first filtering treatment, greatly improving the metal enrichment efficiency, and through the first filtering treatment, the first filtrate produced can not detect the presence of noble metal.

[0088] In the present application, the detection of the presence of noble metal refers to the use of an atomic spectrophotometer with a detection lower limit of 0.03 mg / L, and no noble metal is detected.

[0089] Next, in step 3), the first filtering product from which the first part of the filtrate is removed through the first filtering treatment is subjected to a second filtering treatment to achieve further enrichment of the noble metal.

[0090] The inventors of the present application have found that after the first filtering treatment, the fine activated carbon particles originally grown by acid treatment will partially separate due to the first filtering treatment and transportation, etc.

[0091] Therefore, in the second filtering treatment, unlike conventional secondary filtering operations, the pore size of the second filtering medium cannot be greater than the upper limit of the pore size of the first filtering medium, and the inventors have found through extensive research that the pore size of the second filtering medium is less than 5 μm, thereby ensuring that the second filtrate produced by the second filtering treatment cannot detect the presence of noble metal, and the treatment efficiency can be ensured.

[0092] In the present application, the second filtering treatment can be performed by various filtering devices commonly used in the art, without particular limitation. For example, the first filtering treatment can be performed by one or more of a horizontal paperboard filter, a plate-and-frame filter press, and a vacuum filter.

[0093] In the present application, the second filtering treatment is preferably performed by a horizontal paperboard filter. As such a filter, for example, a horizontal paperboard filter of Model VSZB-5-304-F50PN6-G available from Shanghai Weichi Filtration System Co., Ltd. can be used.

[0094] In the present application, the second filtering medium is not particularly limited and can be, for example, paperboard, filter cloth, or filter paper, and is preferably filter paper.

[0095] According to the present application, the purpose of the second filtering treatment is to further separate the remaining water and the activated carbon particles loaded with noble metal in the first filtering product, so as to further reduce the content of water.

[0096] In the second filtering treatment, the pore size of the second filtering medium is preferably 1-5 μm, so that the second filtrate obtained by the second filtering treatment is free of noble metal, and the enrichment efficiency of noble metal is further improved.

[0097] In the present application, the conditions of the second filtering treatment are not particularly limited and can be the conventional filtering conditions in the art. However, the present inventors have found through a large number of practices that, in the second filtering treatment, the pressure parameter of the second filtering treatment is critical. If the pressure is too high, the filtering medium can be broken or the sealing of the equipment can be damaged. If the pressure is insufficient, the filtering efficiency can be too low, and the separation capacity can be limited, which is not conducive to the enrichment of metal.

[0098] Therefore, in the present application, preferably, the pressure of the second filtering treatment is 0.5 MPa or less, and more preferably 0.1-0.5 MPa.

[0099] In the present application, through the second filtering treatment, the solid content in the second filtering product can be 70-85 wt%, and preferably 70-80 wt%. Thus, the water and the activated carbon particles loaded with noble metal can be further separated in the process of the second filtering treatment, so as to greatly improve the enrichment efficiency of metal, and the second filtering treatment can make the second filtrate free of noble metal.

[0100] According to the present application, through the first filtering process and the second filtering process, water in the wastewater containing noble metal and activated carbon particles can be separated to the maximum extent, and the second filtering product with a solid content of 70-85 wt% is obtained, and the enrichment of the noble metal is efficiently achieved.

[0101] In order to further improve the enrichment effect, preferably, the method further comprises a step of drying the second filtering product.

[0102] In the present application, the method for the drying process is not particularly limited, as long as the moisture in the second filtering product can be removed as much as possible.

[0103] The present inventors have found that, for the second filtering product of the present application, the drying process is sequentially performed by using the aeration drying and the heating drying, thereby greatly reducing the time required for the drying process, and also reducing the energy consumption, and being more suitable for large-scale industrial processing.

[0104] According to the present application, the gas introduced in the aeration drying is not particularly limited, for example, it can be air, nitrogen, etc., and is preferably air.

[0105] In addition, in the aeration drying, the aeration amount can be 5-15 m 3 / h, preferably 5-10 m 3 / h, with respect to 1 kg of the second filtering product. Thereby, the processing efficiency can be further improved.

[0106] In addition, the conditions for the aeration drying are not particularly limited, for example, the conditions for the aeration drying can include: temperature of 20-40℃, pressure of 0.1-0.5 MPa, and time of 10-30 min; preferably, the conditions for the aeration drying can include: temperature of 25-35℃, pressure of 0.2-0.4 MPa, and time of 20-30 min. Thereby, the efficiency of the aeration drying can be further improved.

[0107] In the present application, through the aeration drying process, the water content of the dried product can be controlled to be 10-30 wt%, more preferably 10-15 wt%. Thereby, the overall processing time can be further shortened, and the enrichment efficiency can be improved.

[0108] On the other hand, in the present application, the conditions for the heating drying are not particularly limited, for example, the conditions for the heating drying can include: temperature of 50-120℃, and time of 24-72 h; preferably, the conditions for the heating drying can include: temperature of 80-120℃, and time of 24-48 h.

[0109] Further, in the present application, preferably, the drying treatment is performed so that the water content of the obtained dried treatment product is 1% by weight or less.

[0110] By the method of the first aspect of the present application, the noble metal in the wastewater containing noble metal and activated carbon particles can be enriched very simply, and the required time is greatly shortened, while the enrichment rate is extremely high, and the noble metal cannot be detected in the water body discharged after enrichment.

[0111] According to a particularly preferred embodiment of the present application, the wastewater produced during reduction washing in the production process of palladium-carbon catalyst is treated, the wastewater contains palladium and activated carbon particles, the content of the palladium is 0.1-1 mg / L, the content of the activated carbon particles is 4-6 mg / L, and the particle size of the activated carbon particles is greater than 1 μm, the average particle size of the activated carbon particles is 20-30 μm, the number of activated carbon particles with a particle size of 5 μm or less accounts for 10-12% of the total number of activated carbon particles, and the pH of the wastewater is 9-10.

[0112] The treatment process according to a preferred embodiment of the present application is shown in Figure 1 .

[0113] First, the wastewater is mixed with 5-15% by weight of an aqueous hydrochloric acid solution, and acid treatment is performed for 4-6 h, so that the pH of the acid treatment product is 7-8, and the particle size of the activated carbon particles in the acid treatment product is greater than 20 μm after the acid treatment.

[0114] Then, the obtained acid treatment product is subjected to first filtration treatment by a precision filter, the first filtration medium is a high molecular polyethylene filter core, the pore size is 5-20 μm, the pressure of the first filtration treatment is 0.1-0.2 MPa, and the solid content of the first filtration product is 2.5-3% by weight after the first filtration treatment.

[0115] Next, the first filtration product is subjected to second filtration treatment by a horizontal paper board filter, the second filtration medium is filter paper, the pore size is 1-5 μm, the pressure of the second filtration treatment is 0.1-0.5 MPa, and the solid content of the second filtration product is 70-80% by weight after the second filtration treatment.

[0116] Then, the obtained second filtration product is subjected to ventilation drying and heating drying in sequence, wherein the ventilation drying is performed by air, the ventilation amount of the air is 5-10 m 3 / h per 1 kg of the second filtration product, the temperature of the ventilation drying is 25-35 °C, the pressure is 0.2-0.4 MPa, and the time is 20-30 min; the conditions of the heating drying treatment include a temperature of 80-120 °C and a time of 24-48 h.

[0117] By the method of the first aspect of the present application, not only can the noble metal be efficiently recovered, but also no noble metal can be detected in the filtrate produced by the two filtrations, which can be directly discharged, and the above treatment method can greatly reduce the treatment time.

[0118] The second aspect of the present application provides an application of the method of the first aspect of the present application in treating wastewater produced in the production of palladium-carbon catalyst.

[0119] The present application will be described in detail below through examples.

[0120] In the following examples and comparative examples, the palladium content is measured by an atomic spectrophotometer of model Pinaade-900F purchased from PerkinElmer Company, and the lower limit of detection is 0.03 mg / L;

[0121] The precision filter used is purchased from Shanghai Weichi Filtration System Co., Ltd., and the model is VMTF-10-304-F0PN-G;

[0122] The horizontal paperboard filter used is purchased from Shanghai Weichi Filtration System Co., Ltd., and the model is VSZB-5-304-F50PN6-G;

[0123] The wastewater used in the following examples and comparative examples is wastewater produced in the reduction and washing process in the preparation of palladium-carbon catalyst by Sinopec Catalyst Co., Ltd. Shanghai Branch, and the palladium content in the wastewater is 0.18 mg / L, the active carbon particle content is 4 mg / L, the pH of the wastewater is 9, and the particle size distribution of the active carbon particles is shown in the following table:

[0124] Average particle size 1 μm or less 1-3 μm 3-5 μm 5-10 μm 10-20 μm 20-40 μm 40-50 μm 50-80 μm 80-200 μm 25.5 μm 0％ 4.3％ 6.67％ 19.46％ 29.31％ 23.79％ 5.08％ 7.15％ 3.46％

[0125] Note: The % refers to the percentage of the number of active carbon particles in the corresponding particle size range to the total number of active carbon particles.

[0126] Example 1

[0127] 1) 1000 kg of wastewater is introduced into a flocculation tank, and 10% by weight of an aqueous hydrochloric acid solution is added thereto under stirring to adjust the pH of the wastewater to 7, and then it is left to stand for 5 h to obtain an acid treatment product, and the particle size of the active carbon particles in the obtained acid treatment product is greater than 20 μm;

[0128] 2) The acid treatment product obtained in step 1) is introduced into a precision filter for first filtration treatment, wherein the filtration medium of the precision filter is a high molecular polyethylene filter core, the pore size of which is 20 μm, and the pressure of the first filtration treatment is 0.1 MPa, to obtain a first filtrate and a first filtration product, wherein no palladium is detected in the first filtrate, and the solid content of the first filtration product is 2.5% by weight;

[0129] 3) The first filtration product obtained in step 2) is subjected to a second filtration treatment in a horizontal paperboard filter, wherein the filtration medium of the horizontal paperboard filter is a cotton fiber filter paper with a pore size of 5 μm, and the pressure of the second filtration treatment is 0.1 MPa, to obtain a second filtrate and a second filtration product, wherein the second filtrate does not detect the presence of palladium, and the solid content of the second filtration product is 70 wt.%;

[0130] 4) The second filtration product obtained in step 3) is subjected to air drying in a horizontal paperboard filter, wherein the air is used as the gas, the air volume is 10 m 3 / h relative to 1 kg of the second filtration product, the air drying time is 10 min, and the water content of the product after air drying is 15 wt.%;

[0131] 5) The air-dried product obtained in step 4) is subjected to heating drying in a mesh belt kiln, wherein the temperature is 120°C, and the time is 24 h, to obtain an enriched product with a water content of 0.6 wt.%.

[0132] In this embodiment, the total processing time of steps 1) to 5) is 32 h, and the recovery rate of palladium is 99.1%.

[0133] Example 2

[0134] 1) 1000 kg of wastewater is introduced into a flocculation tank, and 10 wt.% of hydrochloric acid aqueous solution is added thereto under stirring to adjust the pH of the wastewater to 6, and then it is left to stand for 6 h to obtain an acid treatment product, wherein the particle size of the activated carbon particles in the obtained acid treatment product is greater than 20 μm;

[0135] 2) The acid treatment product obtained in step 1) is subjected to a first filtration treatment in a precision filter, wherein the filtration medium of the precision filter is a high molecular polyethylene filter core with a pore size of 10 μm, and the pressure of the first filtration treatment is 0.1 MPa, to obtain a first filtrate and a first filtration product, wherein the first filtrate does not detect the presence of palladium, and the solid content of the first filtration product is 2.3 wt.%;

[0136] 3) The first filtration product obtained in step 2) is subjected to a second filtration treatment in a horizontal paperboard filter, wherein the filtration medium of the horizontal paperboard filter is a cotton fiber filter paper with a pore size of 3 μm, and the pressure of the second filtration treatment is 0.2 MPa, to obtain a second filtrate and a second filtration product, wherein the second filtrate does not detect the presence of palladium, and the solid content of the second filtration product is 75 wt.%;

[0137] 4) The second filtration product obtained in step 3) is subjected to air drying in a horizontal paperboard filter, the air flow is 15 m 3 / h per 1 kg of the second filtration product, the air drying time is 30 h, and the water content of the product after air drying is 10 wt.%;

[0138] 5) The air-dried product obtained in step 4) is subjected to heat drying in a mesh belt kiln at a temperature of 80°C for 48 h to obtain an enriched product with a water content of 0.6 wt.%.

[0139] In this example, the total processing time of steps 1) to 5) is 38 h, and the palladium recovery rate is 99.3%.

[0140] Example 3

[0141] 1) 1000 kg of waste water is introduced into a flocculation tank, and 10 wt.% of an aqueous hydrochloric acid solution is added thereto under stirring to adjust the pH of the waste water to 8, and then it is allowed to stand for 4 h to obtain an acid-treated product, and the particle size of the activated carbon particles in the obtained acid-treated product is greater than 20 μm;

[0142] 2) The acid-treated product obtained in step 1) is subjected to first filtration treatment in a precision filter, wherein the filtration medium of the precision filter is a high-molecular polyethylene filter core with a pore size of 5 μm, and the first filtration treatment is performed at a pressure of 0.15 MPa to obtain a first filtrate and a first filtration product, wherein the first filtrate does not detect the presence of palladium, and the solid content of the first filtration product is 2.9 wt.%;

[0143] 3) The first filtration product obtained in step 2) is subjected to second filtration treatment in a horizontal paperboard filter, wherein the filtration medium of the horizontal paperboard filter is a cotton fiber filter paper with a pore size of 1 μm, and the second filtration treatment is performed at a pressure of 0.5 MPa to obtain a second filtrate and a second filtration product, wherein the second filtrate does not detect the presence of palladium, and the solid content of the second filtration product is 80 wt.%;

[0144] 4) The second filtration product obtained in step 3) is subjected to air drying in a horizontal paperboard filter, the air flow is 15 m 3 / h per 1 kg of the second filtration product, the air drying time is 30 h, and the water content of the product after air drying is 10 wt.%;

[0145] 5) The air-dried product obtained in step 4) is subjected to heat drying in a mesh belt kiln at a temperature of 80°C for 48 h to obtain an enriched product with a water content of 0.6 wt.%.

[0146] In this example, the total processing time used was 56 h, and the palladium recovery rate was 99.2%.

[0147] Example 4

[0148] The procedure of Example 1 was followed, except that:

[0149] Instead of the air-drying of Step 4), the heating-drying of Step 5) was directly performed;

[0150] In Step 5), the second filtration product obtained in Step 3) was subjected to heating-drying in a mesh belt kiln at a temperature of 120°C until an enriched product having a water content of 0.6% by weight was obtained.

[0151] In this example, the total processing time used was 91 h, and the palladium recovery rate was 99.1%.

[0152] Comparative Example 1

[0153] The procedure of Example 1 was followed, except that:

[0154] In Step 1), the wastewater was mixed with 0.005 kg of polyacrylamide for flocculation treatment, and a flocculation product was obtained after standing for 4 h. The particle size of the activated carbon particles in the obtained flocculation product was greater than 20 μm.

[0155] After that, during the first filtration treatment, the flocculation product formed a colloid and could not pass through the filter core, so that the filtration could not be smoothly performed, and the enrichment could not be smoothly achieved.

[0156] Comparative Example 2

[0157] The procedure of Example 1 was followed, except that:

[0158] Instead of the first filtration treatment of Step 2), the acid treatment product obtained in Step 1) was directly passed through the horizontal paperboard filter of Step 3) for filtration treatment to obtain a filtrate and a filtration product, and the solid content of the filtration product was 75% by weight;

[0159] After that, the filtration product was subjected to air-drying according to the procedure of Step 4) of Example 1;

[0160] Finally, the air-drying product was subjected to heating-drying according to the procedure of Step 5) of Example 1 at a temperature of 120°C until an enriched product having a water content of 0.6% by weight was obtained.

[0161] In this comparative example, the total processing time used was 40 h, and the palladium recovery rate was 85.3%.

[0162] Comparative Example 3

[0163] The process was carried out as described in Example 1, except that

[0164] The second filtration process described in step 3) was not carried out, and the first filtration product obtained in step 2) was directly subjected to the air-drying process described in step 4) of Example 1. After air-drying, the water content of the product was 80% by weight;

[0165] Subsequently, the air-dried product was subjected to the heat-drying process described in step 5) of Example 1 at a temperature of 120°C until an enriched product with a water content of 0.6% by weight was obtained.

[0166] In this comparative example, the total treatment time was 78h, and the palladium recovery rate was 89.6%.

[0167] Comparative Example 4

[0168] The wastewater was directly introduced into a plate-and-frame filter press for pressure filtration treatment, using synthetic fiber filter cloth with a pore size of 20μm as the filtration medium. The filtrate and filtration product were obtained, and the palladium content in the filtrate was 0.06mg / L.

[0169] Subsequently, the filtration product obtained was subjected to the heat-drying process described in step 5) of Example 1 at a temperature of 120°C until an enriched product with a water content of 0.6% by weight was obtained.

[0170] In this comparative example, the total treatment time was 60h, and the palladium recovery rate was 65%.

[0171] The above detailed the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A method for enriching precious metals from wastewater containing precious metals and activated carbon particles, wherein the precious metals are loaded onto the activated carbon particles, characterized in that, The method includes the following steps: 1) The wastewater is mixed with acid and subjected to acid treatment to obtain the acid-treated product; 2) The acid-treated product is subjected to a first filtration process using a first filter medium with a pore size of less than 20 μm to obtain a first filtered product; 3) The first filtered product is subjected to a second filtration process using a second filter medium with a pore size of less than 5 μm to obtain a second filtered product. The acid treatment results in activated carbon particles in the acid-treated product having a particle size greater than 20 μm. The first filtration process results in a solids content of 2-3% by weight in the first filtration product. The second filtration process results in a solids content of 70-85% by weight in the second filtration product. The method further includes a step of drying the second filtered product, wherein the drying process is performed by sequentially using air drying and heat drying.

2. The method according to claim 1, wherein, The content of precious metals in the wastewater is 0.1-2 mg / L; The precious metal is one or more of palladium, platinum and gold; The content of activated carbon particles in the wastewater is 2-6 mg / L; The wastewater is generated during the preparation of palladium on carbon catalyst.

3. The method according to claim 1, wherein, The content of precious metals in the wastewater is 0.1-1 mg / L; The precious metal is palladium; The content of activated carbon particles in the wastewater is 4-6 mg / L; The wastewater is generated during the reduction and washing of the palladium-on-carbon catalyst.

4. The method according to claim 1, wherein, The activated carbon particles in the wastewater have a particle size greater than 1 μm; The number of activated carbon particles with a diameter of less than 5 μm accounts for 5-15% of the total number of activated carbon particles; The pH of the wastewater is 9-10.

5. The method according to any one of claims 1-4, wherein, In step 1), the acid is selected from one or more of sulfuric acid, hydrochloric acid, and nitric acid; The acid treatment time is 2-10 hours; The pH of the acid-treated product is 6-8.

6. The method according to any one of claims 1-4, wherein, In step 1), the acid is hydrochloric acid; The acid treatment time is 4-6 hours; The pH of the acid-treated product is 7-8.

7. The method according to any one of claims 1-4, wherein, In step 2), the pore size of the first filter medium is 5-20 μm.

8. The method according to any one of claims 1-4, wherein, In step 2), the pressure of the first filtration process is 0.1-0.3 MPa; The first filtration process results in a solids content of 2.5-3% by weight in the first filtration product.

9. The method according to any one of claims 1-4, wherein, In step 3), the pore size of the second filter medium is 1-5 μm.

10. The method according to any one of claims 1-4, wherein, In step 3), the pressure of the second filtration process is below 0.5 MPa; The second filtration process results in a solids content of 70-80% by weight in the second filtration product.

11. The method according to any one of claims 1-4, wherein, During the aeration drying process, the aeration rate is 5-15 m³ / kg relative to 1 kg of the second filtered product. 3 / h; The conditions for ventilation drying include: temperature of 20-40℃, pressure of 0.1-0.5MPa, and time of 10-30min; The moisture content of the product after air drying is 10-30% by weight. The conditions for heating and drying include: a temperature of 50-120℃ and a time of 24-72h.

12. The application of the method according to any one of claims 1-11 in the treatment of wastewater from the production of palladium-carbon catalyst.

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