Extractant and method for purifying alkaline gold-containing wastewater

Abstract

The present application provides an extractant and a method for purifying alkaline gold-containing wastewater, belonging to the field of wastewater purification. The extractant uses a rigid bisphenol fluorene ring to replace the traditional aliphatic long-chain skeleton. Its unique V-shaped spatial configuration forms a molecular pre-organized cavity through phenolic bond bridging, accurately matching the linear / planar geometric configuration of the gold-cyanide complex, and significantly enhancing the coordination binding ability. Through the molecular structure, the π electron system of the bisphenol fluorene skeleton works synergistically with the thioamide group, weakening the Au-CN bond through π-d electron coupling, while constructing a sulfur-oxygen dual active site to hierarchically capture Au. + / Au 3+ , achieving directional dissociation of the complex and adaptive chelation of the valence state. This application optimizes interface regulation, forms a gradient interfacial tension layer through the hydrophobic segments connected by phenolic bonds, greatly accelerates the phase separation process, achieves a gold recovery rate of >95%, overcomes the synergistic problem of highly selective extraction and deep purification, and achieves the purpose of purifying alkaline cyanide gold-containing wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of alkaline gold-containing wastewater purification, and in particular to an extractant and a method for purifying alkaline gold-containing wastewater using the extractant. Background Art

[0002] In the chemical and electroplating industries, gold-containing wastewater usually exists in the form of cyanide complexes. This type of wastewater is not only highly toxic but also has high resource value. Its component characteristics and treatment difficulties are mainly reflected in two aspects: First, the gold element in the wastewater exists stably in the form of cyanide complexes, where [Au(CN)2] - (Au + ) accounts for 60-75%, [Au(CN)4] - (Au 3+ ) accounts for 25-40%, the free cyanide concentration is as high as 280-500 mg / L, and the gold-cyanide complex (calculated as Au) content is as high as 10-100 mg / L, forming a complex multiphase system. Secondly, existing treatment technologies face two bottlenecks. Traditional chemical methods have serious defects. For example, the alkaline chlorination method can generate highly toxic gases, leading to secondary pollution. The Au2S3 produced by the sulfide precipitation method is easily re-dissolved, resulting in the loss of precious metals. Ion exchange resins are easily inactivated by cyanide poisoning. Activated carbon adsorption leads to resource waste due to low desorption efficiency (<65%). In addition, the existing extraction system has key performance defects in engineering applications, such as insufficient extraction capacity, sluggish phase separation kinetics, and poor selectivity (Au / Fe separation coefficient <50), which seriously restrict the efficient recovery of gold and deep purification of wastewater.

[0003] Currently, the extraction agents used in the treatment of gold-containing cyanide wastewater in China are primarily imported, resulting in a surge in precious metal recovery costs. However, in the treatment of high-order gold-cyanide complexes, imported extraction agents exhibit inherent flaws such as poor adaptability (pH tolerance range <9-11) and low cyclic stability, resulting in significant annual abnormal gold loss.

[0004] In view of this, it is necessary to design an improved extractant and a method for purifying alkaline gold-containing wastewater to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides an extractant and a method for purifying alkaline gold-containing wastewater, aiming to solve the technical problems of insufficient extraction capacity and poor selectivity of existing extractants.

[0006] In a first aspect, the present application provides an extractant, the structural formula of the extractant is as follows:

[0007] .

[0008] In a second aspect, the present application provides a method for purifying alkaline gold-containing wastewater using an extractant, wherein the extractant described in the first aspect is used for extraction, comprising the following steps:

[0009] S1. The extractant is mixed and dissolved with sulfonated kerosene to obtain a dilution;

[0010] S2. Add a pH regulator to adjust the pH value of the gold-containing wastewater to alkaline, add the diluent, shake in a water bath for a predetermined time, and selectively extract the gold in the wastewater.

[0011] As a further improvement of the present application, the volume ratio of the extractant to sulfonated kerosene is 1:(10~100).

[0012] As a further improvement of the present application, the pH regulator is a sodium hydroxide solution, which adjusts the pH value of the gold-containing wastewater to 8-14.

[0013] As a further improvement of the present application, the gold-containing wastewater is one or more of metallurgical cyanide gold-containing waste liquid, electronic waste cyanide leaching solution, and waste circuit board electroplating solution.

[0014] As a further improvement of the present application, the temperature of the water bath oscillation is 25-28° C., and the time is 5-10 minutes.

[0015] The beneficial effects of this application are:

[0016] This application provides an extractant and a method for purifying alkaline gold-containing wastewater. The extractant uses a rigid bisphenol fluorene ring to replace the traditional aliphatic long-chain skeleton. Its unique V-shaped spatial configuration forms a molecular pre-organized cavity through phenolic bond bridging, accurately matching the linear / planar geometric configuration of the gold-cyanide complex, and significantly enhancing the coordination binding ability. Through the molecular structure, the π electron system of the bisphenol fluorene skeleton works synergistically with the thioamide group, weakening the Au-CN bond through π-d electronic coupling, while constructing a sulfur-oxygen dual active site to hierarchically capture Au. + / Au 3+ , achieving directional dissociation of the complex and valence-adaptive chelation.

[0017] This application optimizes interface regulation, and the hydrophobic segments connected by phenolic bonds form a gradient interfacial tension layer, which greatly accelerates the phase separation process and achieves a gold recovery rate of >95%. It overcomes the synergistic problem of high-selective extraction and deep purification, and achieves the purpose of purifying alkaline cyanide gold-containing wastewater.

[0018] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0020] Figure 1 The synthetic route of the extractant provided in Example 15 of the present application;

[0021] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the extractant provided in Example 15 of the present application. DETAILED DESCRIPTION

[0022] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0024] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0025] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] In the field of cyanide gold-containing wastewater treatment, the existing extraction system has problems such as insufficient extraction capacity, slow phase separation kinetics and poor selectivity in engineering applications. Imported extraction agents are expensive and have poor adaptability, resulting in serious abnormal gold loss each year.

[0028] In order to solve the technical problems of insufficient extraction capacity and poor selectivity of existing extractants, the present application provides an extractant and a method for purifying alkaline gold-containing wastewater thereof. Specifically, through the molecular level design of the extractant, the technical bottleneck in the field of cyanide gold-containing wastewater treatment is broken through, thereby achieving the technical effect of highly selective extraction of gold and purification of alkaline gold-containing wastewater.

[0029] In a first aspect, the present invention provides an extractant having the following structural formula:

[0030] .

[0031] In the technical solution of the present application's examples, molecular design employs a rigid bisphenol fluorene ring and a thioamide group to achieve directional dissociation and valence-adaptive chelation of the gold-cyanide complex. This method accelerates phase separation through a gradient interfacial tension layer, achieving a 95% gold recovery rate and addressing the challenges of highly selective extraction and deep purification.

[0032] In a second aspect, an embodiment of the present application provides a method for purifying alkaline gold-containing wastewater using an extractant, wherein the extraction is performed using the extractant described in the first aspect, comprising the following steps:

[0033] S1. The extractant is mixed and dissolved with sulfonated kerosene to obtain a dilution;

[0034] S2. Add a pH regulator to adjust the pH value of the gold-containing wastewater to alkaline, add a diluent, and oscillate in a water bath for a predetermined time to selectively extract the gold in the wastewater.

[0035] In the technical solution of the embodiment of the present application, gold can be efficiently and selectively recovered from wastewater by using a specific extractant and optimizing pH conditions.

[0036] Furthermore, in some embodiments, the volume ratio of the extractant to the sulfonated kerosene is 1:(10-100).

[0037] In the technical solution of the present embodiment, the setting of the ratio helps ensure the appropriate solubility of the extractant in the sulfonated kerosene, thereby improving extraction efficiency. Dissolving the extractant in the sulfonated kerosene allows for better control of the extraction process, resulting in more efficient gold ion extraction. It also facilitates subsequent phase separation operations, thereby improving overall gold recovery and purification effectiveness.

[0038] Furthermore, in some embodiments, the pH adjuster is a sodium hydroxide solution, which adjusts the pH value of the gold-containing wastewater to 8-14.

[0039] In the technical solutions of the embodiments of this application, adjusting the pH value optimizes the interaction between the extractant and the gold-cyanide complex, thereby improving the gold extraction efficiency. Under alkaline conditions, the gold-cyanide complex is more stable, which facilitates the extraction process. Furthermore, an appropriate pH range can reduce interference from other metal ions, improve extraction selectivity, and ensure efficient gold recovery. Specifically, the concentration of the sodium hydroxide solution is 0.1 to 5 mol / L.

[0040] Furthermore, in some embodiments, the gold-containing wastewater is one or more of metallurgical cyanide gold-containing waste liquid, electronic waste cyanide leaching solution, and waste circuit board electroplating solution.

[0041] In the technical solution of the embodiment of the present application, the extractant is suitable for a variety of gold-containing wastewaters. After treatment, these gold-containing wastewaters can effectively recover the gold resources therein, thereby realizing resource recycling.

[0042] Furthermore, in some embodiments, the temperature of the water bath oscillation is 25-28° C., and the time is 5-10 min.

[0043] In the technical solution of the present embodiment, water bath oscillation allows the extractant to bind more quickly and evenly to the gold-cyanide complex. The oscillation process helps form a gradient interfacial tension layer, allowing for faster separation of the extracted organic and aqueous phases, thereby improving overall processing efficiency. By optimizing temperature and time, the slow reaction rate and low separation efficiency of traditional extraction methods can be overcome, thereby achieving efficient gold recovery.

[0044] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0045] Example 1

[0046] Example 1 provides a method for purifying alkaline gold-containing wastewater using an extractant, wherein the extractant has a molecular structure of

[0047] ; Specifically including the following steps:

[0048] S1. Mix the extractant and sulfonated kerosene at a volume ratio of 1:10 and ultrasonically dissolve to obtain a dilute solution;

[0049] S2. Adjust the pH of the gold-containing wastewater to 8 with sodium hydroxide solution. At room temperature, weigh 150 mL of the diluted solution of the above-mentioned extractant and add it to 50 mL of metallurgical cyanide gold-containing wastewater containing gold ions. Oscillate in a water bath oscillator at 25°C for 5 minutes, separate the organic phase, and use ICP-OES (inductively coupled plasma optical emission spectrometry) to detect the gold concentration in the inorganic liquid phase solution, thereby calculating the extraction rate of the extractant. The detection error of ICP-OES is ±2%.

[0050] Example 2

[0051] Example 2 provides a method for purifying alkaline gold-containing wastewater with an extractant. Compared with Example 1, the only difference is that the water bath oscillation temperature is 28°C and the time is 10 minutes. The other experimental parameters and conditions are basically the same as those in Example 1 and are not repeated here.

[0052] Examples 3-8 and Comparative Example 1

[0053] Examples 3-8 and Comparative Example 1 each provide a method for purifying alkaline gold-containing wastewater using an extractant. Compared with Example 1, the only difference is that the pH value of the gold-containing wastewater is different, as shown in Table 1. Other experimental parameters and conditions are basically the same as those in Example 1 and are not repeated here.

[0054] The extraction effect of the extractant provided in this application on gold ions is shown in Table 1.

[0055] Table 1 Extraction effect

[0056]

[0057] Table 1 shows that the extractant provided in Example 1 has a highly efficient extraction capacity for gold in an alkaline cyanide solution, achieving an extraction efficiency exceeding 95% within the pH range of 8 to 14. The extractant has a wide window of use in alkaline environments. However, the extractant decomposes under acidic and neutral conditions. Furthermore, under acidic conditions, cyanide ions decompose into highly toxic hydrogen cyanide (HCN) gas, which was not tested.

[0058] Examples 9-12

[0059] The extractant provided in Example 1 was used to extract and separate gold from various coexisting ion solutions. The specific steps are as follows:

[0060] A series of sodium cyanide mixed solutions containing gold and iron, aluminum, cobalt, and zinc at varying concentration ratios were prepared. The sodium cyanide concentration was 5 g / L, and the pH of the solution was 10. 100 mL of the diluted extractant provided in Example 1 was added to 50 mL of each solution. After oscillation in a 25°C water bath shaker for 5 minutes, the inorganic liquid phase was collected and the concentration of each metal ion in the solution was measured by ICP-OES to calculate the extraction yield.

[0061] The extraction effects of the extractants on the metal ions in the blend solution are shown in Table 2.

[0062] Table 2 Extraction ability of the extractants for each metal ion in the blend solution

[0063]

[0064] — represents the value below the detection limit of ICP-OES.

[0065] As shown in Table 2, the extractant has a selective extraction effect on gold in the cyanide solution, while basically does not extract other metal ions, such as iron, aluminum, cobalt, and zinc. The main reason is attributed to the unique molecular structure and spatial structure of the extractant, and the coordinated effect between the functional groups, which achieves the effect of efficient selective chelating extraction of gold ions in the cyanide solution.

[0066] Examples 13-14

[0067] Examples 13-14 respectively provide a method for purifying alkaline gold-containing wastewater using an extractant. Compared with Example 1, the only difference is the type of gold-containing wastewater, as shown in Table 3. Other experimental parameters and conditions are basically the same as those in Example 1 and are not repeated here.

[0068] Table 3 Extraction effect of different gold-containing wastewaters

[0069]

[0070] It can be seen from Table 3 that the extractants have high selective extraction capabilities for specific gold-containing wastewater.

[0071] Example 15

[0072] Example 15 provides a method for preparing the extractant in Example 1, such as Figure 1 As shown, the specific steps include:

[0073] S1. Add 0.1 mol of A to 200 mL of anhydrous tetrahydrofuran solution and dissolve. Then, add 0.5 mol of lithium aluminum hydride to 500 mL of anhydrous tetrahydrofuran solution and stir under nitrogen for 30 min to prepare a suspension. Under a nitrogen atmosphere in an ice-water bath, add the prepared lithium aluminum hydride tetrahydrofuran suspension to the tetrahydrofuran solution containing A via a constant pressure titration funnel and react at low temperature for 24 h. After the reaction is completed, quench with deionized water, filter, collect the liquid phase, extract with ethyl acetate, collect the organic phase, and vacuum evaporate to obtain a colorless oily product B with a yield of 75%.

[0074] S2. Dissolve 0.05 mol of B in 200 mL of carbon disulfide, then add 0.2 mol of sodium hydroxide and reflux for 4 h. After the reaction is complete, reflux and condense at 50°C to remove unreacted carbon disulfide until no more liquid drips out within the boiling range of 50-55°C. Collect the remaining liquid, which is the extractant. The product is an orange-red oil with a yield of 90%. The H NMR spectrum is as follows: Figure 2 As shown, the specific nuclear magnetic test results are as follows: 1HNMR (DMSO, 600MHZ): δ4.50~5.00 (4H, H comes from methylene, the structural fragment is -CH2-), δ6.80~7.00 (6H, where 4 H come from the branched benzene ring H A 、H B , the structural fragment is , the remaining two Hs come from the bifluorene ring Hc, and the structural fragment is ),δ7.01~8.05 (18H, of which 6 Hs are derived from the bifluorene ring H1, H2, and H3, and the structural fragment is The remaining 12 Hs come from the diether benzene rings H4, H5, and H6. The structural fragment is ).

[0075] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. An extractant, characterized in that The structural formula of the extractant is as follows: 。 2. A method for purifying alkaline gold-containing wastewater using an extractant, wherein the extractant according to claim 1 is used for extraction, characterized in that: The following steps are involved: S1. The extractant is mixed and dissolved with sulfonated kerosene to obtain a dilution; S2. Add a pH regulator to adjust the pH value of the gold-containing wastewater to alkaline, add the diluent, oscillate in a water bath for a predetermined time, and selectively extract the gold in the wastewater; The gold-containing wastewater is one or more of metallurgical cyanide gold-containing waste liquid, electronic waste cyanide leaching solution, and waste circuit board electroplating solution.

3. The method for purifying alkaline gold-containing wastewater using an extractant according to claim 2, wherein: The volume ratio of the extractant to sulfonated kerosene is 1:(10-100).

4. The method for purifying alkaline gold-containing wastewater using an extractant according to claim 3, wherein: The pH regulator is a sodium hydroxide solution, which adjusts the pH value of the gold-containing wastewater to 8-14.

5. The method for purifying alkaline gold-containing wastewater using an extractant according to claim 2, wherein: The temperature of the water bath oscillation is 25-28° C., and the time is 5-10 min.

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