Extracting agent and method for purifying alkaline gold-containing wastewater by using same

Abstract

The invention provides an extraction agent and a method for purifying alkaline gold-containing wastewater by using the extraction agent, and belongs to the field of wastewater purification, the extraction agent adopts a rigid bisphenol fluorene ring to replace a traditional aliphatic long-chain skeleton, the unique V-shaped spatial configuration of the extraction agent forms a molecular pre-organization cavity through phenol bond bridging, and the linear / plane geometric configuration of a gold-cyanogen complex is accurately matched, so that the extraction agent has a good extraction effect on the gold-cyanogen complex. The coordination binding capacity is obviously enhanced. Through the synergistic effect of a molecular structure, a pi electron system of a bisphenol fluorene skeleton and a thioamide group, an Au-CN bond is weakened through pi-d electron coupling, and meanwhile, sulfur-oxygen double active sites are constructed to capture Au < + > / Au < 3 + > in a grading manner, so that directional dissociation and valence state self-adaptive chelation of the complex are realized. According to the method, a gradient interfacial tension layer is formed through interface regulation and control optimization and phenol bond connected hydrophobic chain segments, the phase separation process is greatly accelerated, the gold recovery rate is larger than 95%, the cooperation problem of high-selectivity extraction and deep purification is solved, and the purpose of purifying the alkaline cyanided gold-containing wastewater is achieved.

Description

Technical Field

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

[0002] In industries such as chemical engineering and electroplating, gold-containing wastewater usually exists in the form of cyanide complexes. Such wastewater is not only highly toxic but also has high resource value. The 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 concentration of free cyanide ions is as high as 280 - 500 mg / L, and the content of gold cyanide complexes (calculated as Au) is as high as 10 - 100 mg / L, forming a complex multiphase system; Second, the existing treatment technologies face double bottlenecks. Traditional chemical methods have serious defects. For example, the alkaline chlorination method will generate highly toxic gases, resulting in secondary pollution. The sulfide precipitation method produces Au 2 S 3 which is prone to redissolution, causing the loss of precious metals; while ion exchange resins are easily poisoned and inactivated by cyanides; activated carbon adsorption leads to resource waste due to low desorption efficiency (<65%). In addition, the existing extraction systems have key performance defects such as insufficient extraction capacity, slow phase separation kinetics, and poor selectivity (Au / Fe separation coefficient <50) in engineering applications, seriously restricting the efficient recovery of gold and the deep purification of wastewater.

[0003] Currently, the extractants used in the field of cyanide-containing gold wastewater treatment in China mainly rely on imports, resulting in a sharp increase in the cost of precious metal recovery. However, in the treatment scenarios of high-order gold cyanide complexes, imported extractants expose inherent defects such as poor adaptability (pH tolerance range <9 - 11) and low cycle stability, resulting in a serious annual abnormal loss of gold.

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

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

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

[0007] In a second aspect, the present application provides a method for purifying alkaline gold-containing wastewater with an extractant. The extraction is carried out using the extractant described in the first aspect, and the method includes the following steps: S1. Mix and dissolve the extractant with sulfonated kerosene to obtain a dilution solution; S2. Add a pH regulator to adjust the pH value of the gold-containing wastewater to alkaline, add the dilution solution, and perform water bath oscillation for a predetermined time to selectively extract gold in the wastewater.

[0008] As a further improvement of the present application, the volume ratio of the extractant to sulfonated kerosene is 1:(10 - 100).

[0009] As a further improvement of the present application, the pH regulator is a sodium hydroxide solution, and the pH value of the gold-containing wastewater is adjusted to 8 - 14.

[0010] 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.

[0011] 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 min.

[0012] The beneficial effects of the present application are as follows: The present 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, precisely matching the linear / plane 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 and the thioamide group act synergistically. The Au-CN bond is weakened through π-d electron coupling, and at the same time, sulfur-oxygen dual active sites are constructed to hierarchically capture Au + / Au 3+ , realizing the directional dissociation of the complex and valence state self-adaptive chelation.

[0013] Through the optimization of interface regulation, the hydrophobic chain segments connected by phenolic bonds form a gradient interfacial tension layer, greatly accelerating the phase separation process, achieving a gold recovery rate > 95%, overcoming the synergistic problem of high-selectivity extraction and deep purification, and achieving the purpose of purifying alkaline cyanide gold-containing wastewater.

[0014] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of the present application more obvious and understandable, the following specifically illustrates the specific embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0016] Figure 1 It is the synthetic route diagram of the extractant provided in Embodiment 15 of this application; Figure 2 It is the nuclear magnetic resonance hydrogen spectrum diagram of the extractant provided in Embodiment 15 of this application. Specific Embodiments

[0017] The embodiments of the technical solutions of this application will be described in detail below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of this application, so they are only examples and cannot be used to limit the protection scope of this application.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field 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 accompanying drawing descriptions are intended to cover non-exclusive inclusion.

[0019] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means more than two, unless otherwise clearly and specifically defined.

[0020] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0021] In the description of the embodiments of this application, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0022] In the field of treating cyanide-containing gold-bearing wastewater, the existing extraction systems have problems such as insufficient extraction capacity, slow phase separation kinetics, and poor selectivity in engineering applications. Moreover, imported extractants are costly and have poor adaptability, resulting in a serious annual abnormal loss of gold.

[0023] To solve the technical problems of insufficient extraction capacity and poor selectivity of existing extractants, this application provides an extractant and a method for purifying alkaline gold-bearing wastewater. Among them, through molecular design of the extractant, the technical bottleneck in the field of treating cyanide-containing gold-bearing wastewater is broken through, so as to achieve the technical effects of highly selective extraction of gold and purification of alkaline cyanide-containing gold-bearing wastewater.

[0024] In the first aspect, an embodiment of this application provides an extractant, and its structural formula is as follows: 。

[0025] In the technical solution of the embodiment of this application, through molecular design, a rigid bisphenol fluorene ring and a thioamide group are adopted to achieve the directional dissociation and valence-state self-adaptive chelation of gold cyanide complexes. This method accelerates phase separation through a gradient interfacial tension layer, achieving a gold recovery rate of 95%, and solving the problems of highly selective extraction and deep purification.

[0026] In the second aspect, an embodiment of this application provides a method for purifying alkaline gold-bearing wastewater with an extractant. The extraction is carried out using the extractant described in the first aspect, and it includes the following steps: S1. Mix and dissolve the extractant with sulfonated kerosene to obtain a dilution solution; S2. Add a pH regulator to adjust the pH value of the gold-bearing wastewater to alkaline, add the dilution solution, and perform water bath oscillation for a predetermined time to selectively extract the gold in the wastewater.

[0027] In the technical solution of the embodiment of this application, by using a specific extractant and optimizing the pH conditions, gold can be efficiently and selectively recovered from the wastewater.

[0028] Furthermore, in some embodiments, the volume ratio of the extractant to sulfonated kerosene is 1:(10~100).

[0029] In the technical solution of the embodiment of this application, the setting of the ratio helps to ensure the appropriate solubility of the extractant in sulfonated kerosene, thereby improving the extraction efficiency. By dissolving the extractant with sulfonated kerosene, the extraction process can be better controlled, making the extraction of gold ions more efficient. At the same time, it also helps with subsequent phase separation operations, thereby improving the overall gold recovery rate and purification effect.

[0030] Furthermore, in some embodiments, the pH regulator is a sodium hydroxide solution, and the pH value of the gold-bearing wastewater is adjusted to 8~14.

[0031] In the technical solution of the embodiment of the present application, by adjusting the pH value, the interaction between the extractant and the gold cyanide complex can be optimized, thereby improving the extraction efficiency of gold. Under alkaline conditions, the gold cyanide complex is more stable, which is beneficial to the extraction process. In addition, an appropriate pH value range can also reduce the interference of other metal ions, improve the selectivity of extraction, and ensure the efficient recovery of gold. Specifically, the concentration of the sodium hydroxide solution is 0.1 - 5 mol / L.

[0032] Further, 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.

[0033] In the technical solution of the embodiment of the present application, the extractant is applicable to various gold-containing wastewaters. After these gold-containing wastewaters are treated, the gold resources therein can be effectively recovered, realizing the reuse of resources.

[0034] Further, in some embodiments, the temperature of the water bath oscillation is 25 - 28 °C, and the time is 5 - 10 min.

[0035] In the technical solution of the embodiment of the present application, through water bath oscillation, the extractant can combine with the gold cyanide complex more quickly and evenly. The oscillation process helps to form a gradient interfacial tension layer, enabling the organic phase and the aqueous phase after extraction to separate more quickly, thereby improving the overall treatment efficiency. By optimizing the temperature and time, the problems of slow reaction rate and low separation efficiency in traditional extraction methods can be overcome, thus realizing the efficient recovery of gold.

[0036] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation of the present application. For those without specific techniques or conditions noted in the embodiments, they shall be carried out according to the techniques or conditions described in the literature in the art or according to the product specifications. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0037] Example 1 Example 1 provides a method for purifying alkaline gold-containing wastewater with an extractant. The molecular structure of the extractant is ; Specifically, it includes the following steps: S1. Mix the extractant and sulfonated kerosene at a volume ratio of 1:10, and ultrasonically dissolve to obtain a dilution. 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 extractant and add it to 50 mL of the metallurgical cyanide gold-containing waste liquid containing gold ions. After oscillating in a water bath oscillator at 25 °C for 5 min, separate the organic phase, and detect the concentration of gold in the inorganic liquid phase solution with ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer), so as to calculate the extraction rate of the extractant. Among them, the detection error of ICP-OES is ±2%.

[0038] Example 2 Example 2 provides a method for purifying alkaline gold-containing wastewater with an extractant. Compared with Example 1, the only difference is that the temperature of the water bath oscillation is 28 °C and the time is 10 min. Other experimental parameters and conditions are basically the same as those in Example 1 and will not be elaborated here.

[0039] Examples 3-8 and Comparative Example 1 Examples 3-8 and Comparative Example 1 respectively provide a method for purifying alkaline gold-containing wastewater with 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 will not be elaborated here.

[0040] The extraction effect of the extractant provided by this application on gold ions is shown in Table 1.

[0041] Table 1 Extraction effect As can be seen from Table 1, the extractant provided by Example 1 has high extraction ability for gold in alkaline cyanide solution, and the extraction effect reaches more than 95% in the pH range (8-14). The extractant has a wide use window in an alkaline environment. The extractant will decompose under acidic and neutral conditions. In addition, under acidic conditions, cyanide ions decompose into highly toxic hydrogen cyanide (HCN) gas, and no relevant tests have been carried out.

[0042] Examples 9-12 Extract and separate gold from a variety of coexisting ion solutions with the extractant provided by Example 1. The specific operation steps are as follows: Prepare a series of sodium cyanide co-blended solutions containing different concentration ratios of gold to iron, aluminum, cobalt, and zinc. The concentration of sodium cyanide is 5 g / L, and the pH value of the solution is 10. Take 100 ml of the diluted solution of the extractant provided by Example 1 and add it to 50 mL of the solution respectively. After oscillating in a water bath oscillator at 25 °C for 5 min, take the inorganic liquid phase and detect the concentration of each metal ion in the solution with ICP-OES, so as to calculate the extraction rate.

[0043] The extraction effect of the extractant on each metal ion in the co-blended solution is shown in Table 2.

[0044] Table 2 Extraction ability of extractant for various metal ions in the blend solution — Indicates below the detection limit of ICP-OES.

[0045] As can be seen from Table 2, the extractant has a selective extraction effect on gold in the cyanide solution, and basically does not extract other metal ions, such as iron, aluminum, cobalt, and zinc. The main reason is attributed to the unique molecular structure, spatial structure of the extractant, and the coordinated interaction between functionalized functional groups, achieving the effect of efficient selective chelation extraction of gold ions in the cyanide solution.

[0046] Examples 13 - 14 Examples 13 - 14 respectively provide a method for purifying alkaline gold-containing wastewater with 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 will not be elaborated here.

[0047] Table 3 Extraction effect of extractant on different gold-containing wastewaters As can be seen from Table 3, the extractant has a high selective extraction ability for specific gold-containing wastewaters.

[0048] Example 15 Example 15 provides a method for preparing the extractant in Example 1. As Figure 1 shown, it specifically includes the following steps: S1. Add 0.1 mol of A to 200 mL of anhydrous tetrahydrofuran solution and dissolve it. Then, add 0.5 mol of lithium aluminum hydride to 500 mL of anhydrous tetrahydrofuran solution and stir for 30 min under a nitrogen atmosphere to prepare a suspension. Under an ice-water bath and nitrogen atmosphere, add the prepared lithium aluminum hydride tetrahydrofuran suspension to the tetrahydrofuran solution containing A through a constant-pressure dropping funnel and react at low temperature for 24 h. After the reaction, quench with deionized water, filter, collect the liquid phase, extract with ethyl acetate, collect the organic phase, and perform vacuum rotary evaporation to obtain a colorless oily product B with a yield of 75%.

[0049] 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, reflux and condense at 50 °C to remove the unreacted carbon disulfide until no more liquid drips within the boiling range of 50 - 55 °C. Collect the remaining liquid, which is the extractant. The product is an orange-red oily substance with a yield of 90%. The nuclear magnetic resonance hydrogen spectrum is as Figure 2As shown, the specific NMR test results are as follows: 1H NMR (DMSO, 600 MHz): δ 4.50 - 5.00 (4H, H comes from methylene, the structural fragment is -CH 2 -), δ 6.80 - 7.00 (6H, among which 4H come from the branched benzene ring H A 、H B , the structural fragment is , and the remaining 2H come from the Hc of the bis-fluorenyl ring, the structural fragment is ), δ 7.01 - 8.05 (18H, among which 6H come from the H 1 、H 2 、H 3 of the bis-fluorenyl ring, the structural fragment is , and the remaining 12H come from the H 4 、H 5 、H 6 of the ether-linked benzene ring, the structural fragment is ).

[0050] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same function and effect as the technical idea within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various modifications that those skilled in the art can think of to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of this 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 diluent; S2. Add a pH adjuster 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.

3. The method for purifying alkaline gold-containing wastewater using an extractant according to claim 2, characterized in that: 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, characterized in that: 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, characterized in that: 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.

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

Images