Method for recycling valuable substances and cyanide from cyanide-containing wastewater

Abstract

The application provides a method for recycling valuable substances and cyanide in cyanide-containing wastewater, and belongs to the technical field of cyanide-containing wastewater treatment. The method first uses a physicochemical material (reducing substance zinc) to replace copper cyanide complex in the cyanide-containing wastewater to obtain a filter residue containing zinc and copper, so as to realize copper recovery. During the replacement reaction, the copper cyanide complex in the filtrate is converted into zinc cyanide complex with a lower stability constant, and then the zinc in the filtrate is recovered by using a diaphragm electrolysis. Specifically, the electrolytic cell is separated into a cathode zone and an anode zone by using a membrane material, so that the electrode reactions are independent of each other, thereby avoiding the cyanide from entering the anode zone to be electrochemically oxidized, inhibiting the decomposition of the cyanide, recycling the cyanide in the solution, and recycling the cyanide. Then, a titanium-based coating electrode with alkali resistance is used as the anode plate, and a porous material is used as the cathode plate, so as to promote the recovery of zinc on the cathode plate, and realize the recovery of valuable metals zinc and copper and the recycling of cyanide.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cyanide-containing wastewater treatment, and particularly relates to a method for recycling valuable substances and cyanide in cyanide-containing wastewater. BACKGROUND

[0002] The cyanide leaching process has become the mainstream of the current gold industry because of its simple operation and high gold recovery rate. Gold ore is mostly associated with copper minerals. Copper minerals greatly interfere with cyanide leaching, not only slowing down the gold dissolution rate, but also significantly increasing the amount of cyanide used. Moreover, in view of the complex composition of cyanide-containing tailings, the composition contains copper cyanide complex, zinc cyanide complex and iron cyanide complex. Such cyanide tailings must be disposed of in multiple stages to be recycled. The previous single disposal process has obvious defects. For example, acidification recovery has the safety hazard of hydrogen cyanide escaping, the adsorption material has a higher requirement for water quality cleanliness, and in the electrolytic recovery, zinc cyanide and iron cyanide will hinder the recovery of copper in the cyanide-containing tailings, resulting in a decrease in copper recovery efficiency, and various valuable metals are mixed together, making it difficult to achieve effective separation, so that the recycling of various valuable metals does not meet the expected value.

[0003] Therefore, it is urgent to develop a combined disposal process for disposing of cyanide tailings with complex composition to efficiently recover metals and cyanide in cyanide-containing wastewater in an alkaline environment, thereby achieving the goal of clean production and recycling, and promoting the sustainable development of the gold industry. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a method for recycling valuable substances and cyanide in cyanide-containing wastewater. The method provides a safe and environmentally friendly physicochemical material-membrane electrolysis combined disposal process. The present application organically integrates the displacement reaction of reducing substances and membrane electrolysis. First, the displacement reaction of the physicochemical material (reducing substance zinc) and the copper cyanide complex in the cyanide-containing wastewater is used to displace copper, and a copper-zinc mixture is obtained by filtration. During the displacement reaction, the copper cyanide complex in the cyanide-containing wastewater is converted into zinc cyanide complex with a lower stability constant; then the membrane electrolysis disposal process is used, the electrolytic cell is separated into a cathode zone and an anode zone by a membrane, so that the electrode reactions are independent of each other, thereby avoiding the entry of cyanide into the anode zone to cause electrochemical oxidation, inhibiting the decomposition of cyanide, and the zinc cyanide complex in the solution is broken by electrolysis in the cathode zone, and zinc is reduced and precipitated on the cathode plate, thereby realizing zinc recovery.

[0005] The present application provides a method for recycling valuable substances and cyanide in cyanide-containing wastewater, comprising the following steps:

[0006] S1, zinc powder is added to the cyanide-containing wastewater, stirred, and a displacement reaction is carried out under air isolation conditions for 1-4 h, filtered to obtain a filter residue containing zinc and copper and a filter liquid containing zinc cyanide complex;

[0007] S2, electrolyzing the filtrate by using a diaphragm electrolysis device; the diaphragm electrolysis device comprises an electrolytic cell, a diaphragm separating the electrolytic cell into a cathode zone and an anode zone, a cathode plate, an anode plate, and a micro-bubble device arranged in the electrolytic cell; the diaphragm is a cation exchange membrane; the cathode plate is an electrode plate with a porous material; during the electrolysis reaction, the zinc cyanide complex in the filtrate is broken by electrolysis in the cathode zone, and zinc is reduced and precipitated on the cathode plate, thereby realizing zinc recovery.

[0008] The cyanide-containing wastewater is wastewater containing cyanide and heavy metals generated in a cyanide gold extraction process, wherein the heavy metals contain valuable substances zinc and copper.

[0009] Further, the particle size of the zinc powder is greater than 500 mesh.

[0010] Further, during the electrolysis reaction, the pH in the electrolytic cell is 9-14.

[0011] Further, the electrolysis reaction is carried out in a constant current mode, and the constant current is 0.5-2 A.

[0012] Further, the electrolysis reaction is carried out in a constant voltage mode, and the constant voltage is 3.0-10 V.

[0013] Further, the cathode plate is one of graphite felt, activated carbon fiber, carbon felt, foamed copper, foamed nickel, foamed zinc, and foamed stainless steel.

[0014] Further, during the electrolysis reaction, the inter-electrode distance between the anode plate and the cathode plate is 3-7 cm.

[0015] Further, during the electrolysis reaction, the gas amount of the micro-bubble device is 1-4 mL / min.

[0016] Further, the anode plate is a titanium-based coated electrode.

[0017] Further, during the electrolysis reaction, the reaction temperature is the ambient temperature, ranging from 10-30℃, and the reaction time is 1-4 h.

[0018] The application has the following beneficial effects:

[0019] 1.The application provides a method for recycling valuable substances and cyanide in cyanide-containing wastewater. The method organically integrates displacement reaction of reducing substances and diaphragm electrolysis. First, cyanide-containing wastewater is used to react with cyanide copper complex to displace copper by using a physical and chemical material (reducing substance zinc), and copper is obtained by filtration. In the displacement reaction, the cyanide copper complex in the filtrate is converted into a zinc cyanide complex with a lower stability constant. Then, the zinc in the filtrate is recovered by diaphragm electrolysis. The specific recovery principle is as follows: the diaphragm electrolysis method is used to separate the electrolytic cell into a cathode zone and an anode zone by using a membrane material, so that the electrode reactions are independent of each other, thereby avoiding the entry of cyanide into the anode zone to cause electrochemical oxidation and inhibiting the decomposition of cyanide. In this way, the cyanide in the solution is recovered and recycled. Then, a titanium-based coating electrode with alkali resistance is used as an anode plate, and a porous material with a large specific surface area is used as a cathode plate, so as to promote the recovery of zinc on the cathode plate. Finally, the valuable metals zinc and copper in the cyanide-containing wastewater are recovered, and the cyanide is recycled.

[0020] 2.The method of the application can react at room temperature without heating, and can efficiently recover metals and cyanide in cyanide-containing tail liquid in an alkaline environment, so as to realize clean production and recycling of valuable substances and cyanide.

[0021] The above description is only a summary of the technical solutions of the application. In order to more clearly understand the technical means of the application, the specific embodiments of the application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the application, the drawings used in the application will be briefly introduced. Obviously, the drawings described below are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0023] Figure 1 XPS full spectrum of Example 1.

[0024] Figure 2 Reaction process physical diagram of the physical and chemical material stage of Example 1.

[0025] Figure 3 Physical diagram of the reaction product of the physical and chemical material of Example 1.

[0026] Figure 4 Physical diagram of the diaphragm electrolysis reaction process of Example 1. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, but cannot limit the protection scope of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "comprising" and "having," and any variations thereof, as used in the specification and claims herein, are intended to cover not only the inclusive meaning but also the exclusive meaning.

[0029] The purpose of the present application is to provide a safe and environmentally friendly physicochemical material-membrane electrolysis combined disposal process for the complex cyanide tailings generated by the cyanide gold extraction process, to achieve efficient recovery of metals and cyanide in cyanide-containing wastewater in an alkaline environment, and to achieve the goal of clean production and recycling, and to promote the sustainable development of the gold industry.

[0030] The present application provides a method for recycling metals and cyanide by combining physicochemical materials and membrane electrolysis by optimizing the parameters of physicochemical materials and membrane electrolysis.

[0031] The embodiments of the present application provide a method for recycling valuable substances and cyanide in cyanide-containing wastewater, comprising the following steps:

[0032] S1, zinc powder is added to the cyanide-containing wastewater, stirred, and subjected to displacement reaction under air isolation conditions for 1-4h, filtered to obtain filter residue containing zinc and copper and filter liquid containing zinc cyanide complex.

[0033] The cyanide-containing wastewater is wastewater containing cyanide and heavy metals generated by the cyanide gold extraction process, wherein the heavy metals include valuable substances zinc and copper.

[0034] The particle size of the zinc powder is greater than 500 mesh, and smaller particle size can provide more active sites and improve the recovery rate of copper.

[0035] Specifically, the dosage of zinc powder is 1-9 g / L.

[0036] S2, electrolysis of the filter liquid is performed using a membrane electrolysis device.

[0037] The membrane electrolysis device includes an electrolytic cell, a diaphragm separating the electrolytic cell into a cathode zone and an anode zone, a cathode plate, an anode plate, and a micro-bubble device arranged in the electrolytic cell. The diaphragm is a cation exchange membrane.

[0038] The cathode plate adopts a plate with a porous material. For example, one of the following porous materials: graphite felt, activated carbon fiber, carbon felt, foamed copper, foamed nickel, foamed zinc, foamed stainless steel, etc.

[0039] The porous material has high conductivity, can effectively conduct current, reduce electrode resistance, and reduce power loss. Moreover, the unique three-dimensional porous structure of the porous material gives the porous material a large specific surface area, which can increase the contact area between the electrode and the electrolyte, provide more reaction sites for the reduction of cations, and help improve the reduction rate of cations. At the same time, it also helps to reduce the current density on the electrode surface and reduce the occurrence of side reactions. In addition, high porosity can increase the rapid diffusion and penetration of electrolyte inside the electrode, promote the transport of cations to the electrode surface, improve the efficiency of mass transfer, and help maintain the continuous operation of the electrode reaction. Moreover, it can accommodate a certain amount of reaction products, reduce the accumulation of products on the electrode surface, maintain the activity and stability of the electrode, and thus improve the efficiency of copper electrolytic recovery.

[0040] The anode plate is a titanium-based coated electrode, which is resistant to acid and alkali and has a long service life.

[0041] Aeration is performed using a micro-bubble device, and the gas amount of the micro-bubbles is controlled to be 1-4 mL / min.

[0042] The specific surface area of the micro-bubbles of the micro-bubble device is much larger than that of conventional bubbles, which can significantly increase the gas-liquid contact area. When the micro-bubbles rise or break, micro-turbulence is generated in the solution, which breaks the boundary layer on the electrode surface, reduces concentration polarization, and thus increases the ion migration rate and improves the reaction efficiency.

[0043] Preferably, the electrolytic cell is a square grid tank type with stirring function, which can control the inter-electrode distance between the anode plate and the cathode plate, and the inter-electrode distance is 3-7 cm.

[0044] The electrolysis reaction can be carried out at room temperature, generally at 10-30℃.

[0045] The electrolysis reaction is carried out in constant current mode or constant voltage mode, and the reaction time is 1.0-4.0 h.

[0046] When the constant current mode is used, the constant current is 0.5-2 A; when the constant voltage mode is used, the constant voltage is 3.0-10 V.

[0047] During the electrolysis reaction, the pH in the electrolytic cell is 9-14.

[0048] The electrolysis parameters are: constant current of 0.5-2 A, and constant voltage of 3.0-10 V.

[0049] In the electrolysis reaction, the zinc cyanide complex in the filtrate is broken by electrolysis in the cathode zone, and zinc is reduced and precipitated on the cathode plate to realize zinc recovery.

[0050] 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 cannot be understood as a limitation of the present application. If the specific technology or conditions are not specified in the examples, the technology or conditions described in the literature in the art or according to the product manual are used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0051] Example 1

[0052] The experimental water sample is a cyanide-containing tail liquid after cyanide treatment of copper-containing gold ore in a certain gold enterprise, and the main components are shown in Table 1. The unit is mg / L.

[0053] Table 1 Composition of copper cyanide wastewater

[0054]

[0055] The present embodiment provides a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is as follows:

[0056] S1, 1000 mL of cyanide-containing tail liquid from a certain gold enterprise is taken and stirred, 500 mesh zinc powder is added at a dosage of 3 g / L, and air is isolated for reaction, and the reaction time of the displacement reaction is 4 h. After the reaction is completed, filtration is performed to obtain filter residue containing zinc and copper and filter liquid containing zinc cyanide complex. The reaction process is shown in Figure 2 . Figure 3 The physical map of the obtained filter residue is shown in

[0057] S2, assemble a diaphragm electrolysis device, and the filtrate is subjected to electrolysis in the diaphragm electrolysis device, as shown in Figure 4 .

[0058] The diaphragm electrolysis device includes a square lattice cell type electrolytic cell, a cation exchange membrane separating the electrolytic cell into a cathode zone and an anode zone, a cathode plate, an anode plate, and a micro-bubble device arranged in the electrolytic cell.

[0059] Titanium iridium tantalum electrodes are selected as anode plates, and foamed zinc is used as a cathode plate. The cathode and anode electrodes are placed in the cyanide-containing tail liquid, and aeration is performed by a micro-bubble aeration device, and the inter-electrode distance is adjusted to 5 cm; the electrolysis parameters are adjusted, direct current electrolysis is selected, and constant current mode 1.5 A, 5.0 V is used for reaction, and the reaction time is 4 h.

[0060] After the reaction is completed, filtration is performed, and the filtrate is determined.

[0061] Through the calculation analysis, the cyanide recovery rate can reach 93.8%, the copper recovery rate reaches 98.7%, and the zinc recovery rate can reach 70.4%, realizing the cyclic utilization of valuable substances and cyanide.

[0062] The raw water (cyanide-containing tail liquid before treatment) used in Example 1 and the filtrate after treatment were subjected to XPS characterization analysis, and the results are shown in Figure 1 .

[0063] It can be seen that after adopting the combined process of the material-physical and chemical material and diaphragm electrolysis in the present application, the peaks of zinc and copper in the solution disappear, so the content of valuable substances in the solution decreases a lot, indicating that the valuable substances are recycled.

[0064] Comparative Example 1

[0065] The main difference between Comparative Example 1 and Example 1 is that in the replacement reaction in step S1, no stirring is performed and air is not excluded. Other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0066] Experiments show that in Comparative Example 1, the cyanide recovery rate is 90.4%, the copper recovery rate reaches 78.7%, and the zinc recovery rate can reach 32.4%, and the recovery rates of copper and zinc decrease.

[0067] Comparative Example 2

[0068] The main difference between Comparative Example 2 and Example 1 is that stainless steel is used as the cathode plate. Other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0069] Experiments show that in Comparative Example 2, the cyanide recovery rate can reach 89.4%, the copper recovery rate reaches 72.1%, and the zinc recovery rate can reach 58.6%, and the recovery rates of copper and zinc decrease.

[0070] Comparative Example 3

[0071] The main difference between Comparative Example 3 and Example 1 is that the micro-bubble aeration device is replaced by a magnetic stirring device, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0072] Experiments show that in Comparative Example 3, the cyanide recovery rate can reach 97.3%, the copper recovery rate is 56.9%, and the zinc recovery rate is 74.8%, and the copper recovery rate decreases significantly.

[0073] Comparative Example 4

[0074] Comparative Example 4 provides a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is different from Example 1 in that the particle size of zinc powder is 325 mesh, as shown in Table 2, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0075] Example 2-3 and Comparative Example 5

[0076] Example 2-3 and Comparative Example 5 provide a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is different from Example 1 in that the amount of zinc powder is different, as shown in Table 2, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0077] Example 4-5 and Comparative Example 6-7

[0078] Example 4-5 and Comparative Example 6-7 provide a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is different from Example 1 in that the inter-electrode distance of the cathode plate and the anode plate is different, as shown in Table 2, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0079] Example 6 and Comparative Example 8-9

[0080] Example 6 and Comparative Example 8-9 provide a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is different from Example 1 in that the time of electrolysis reaction is different, as shown in Table 2, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0081] Example 7-8 and Comparative Example 10-11

[0082] Example 7-8 and Comparative Example 10-11 provide a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is different from Example 1 in that the reaction current is different, as shown in Table 2, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0083] Example 9 and Comparative Example 12-13

[0084] Example 9 and Comparative Example 12-13 provide a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is different from Example 1 in that the reaction voltage is different, as shown in Table 2, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0085] Comparative Example 14

[0086] The comparative example 14 provides a method for recycling valuable substances and cyanide in cyanide-containing wastewater, which is different from the example 1 in that the cation exchange membrane is replaced by an anion exchange membrane, as shown in Table 2, and other experimental parameters and conditions are basically the same as those of the example 1, which will not be repeated here.

[0087] The electrolysis parameters and detection results of the examples and comparative examples are shown in Table 2.

[0088]

[0089]

[0090] The present application adopts the combined process of physicochemical material-membrane electrolysis to recycle valuable substances and cyanide in cyanide-containing wastewater, and the effects of the related parameters on the experimental results are as follows from the above table:

[0091] In the comparative example 4, the particle size of zinc powder is less than 325 mesh, and the recovery rate of zinc is significantly reduced. It shows that the smaller the particle size, the larger the mesh number, the more conducive to the reaction, and the reaction needs to be stirred and isolated from oxygen.

[0092] Comparing examples 1-3 and comparative example 5, it can be seen that the larger the dosage, the more the copper recovery can be increased, but the zinc powder recovery is reduced, and the reagent cost is increased.

[0093] Comparing examples 1, 4-5 and comparative examples 6-7, it can be seen that when the inter-electrode distance is too small, the mass transfer will be blocked, and when the inter-electrode distance is too large, the resistance will be increased, the electric energy will be wasted, and the experimental effect will be affected.

[0094] Comparing examples 1, 6 and comparative examples 8-9, it can be seen that when the electrolysis reaction time is too short, the reaction is not sufficient, and the effect is not good, and when the reaction time is prolonged, the reaction effect will be improved to some extent, but the energy consumption will be increased.

[0095] Comparing examples 1, 7-9 and comparative examples 10-13, it can be seen that when the reaction current and voltage are too small, the effect is not good, and when the current and voltage are increased, the reaction effect will be increased, but the power consumption will be increased, the cost will be too high, and the economic benefit cost is not suitable.

[0096] In the comparative example 14, the cation exchange membrane is replaced by an anion exchange membrane, and the experiment shows that the use of an anion exchange membrane will cause the ion transmission to be blocked, affecting the reaction effect.

[0097] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art, without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A method for recycling valuable substances and cyanide in cyanide-containing wastewater, characterized in that, Includes the following steps: S1, add zinc powder to cyanide-containing wastewater, stir, carry out displacement reaction for 1-4 hours under air-isolated conditions, filter, and obtain filter residue containing zinc and copper and filtrate containing zinc-cyanide complex; S2, the filtrate is electrolyzed using a diaphragm electrolysis device; the diaphragm electrolysis device includes an electrolytic cell, a diaphragm dividing the electrolytic cell into a cathode region and an anode region, a cathode plate, an anode plate, and a microbubble device disposed in the electrolytic cell; the diaphragm is a cation exchange membrane; the cathode plate is an electrode plate with porous material; during the electrolysis reaction, the zinc cyanide complex in the filtrate is broken down in the cathode region through the electrolysis reaction, and zinc is reduced and precipitated on the cathode plate, thereby realizing zinc recovery.

2. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, The zinc powder has a particle size greater than 500 mesh.

3. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, During the electrolysis reaction, the pH in the electrolytic cell is 9-14.

4. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, The electrolysis reaction is carried out in constant current mode, with a constant current of 0.5~2 A.

5. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, The electrolysis reaction is carried out in a constant voltage mode, with a constant voltage of 3.0~10V.

6. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, The cathode plate is one of the following: graphite felt, activated carbon fiber, carbon felt, copper foam, nickel foam, zinc foam, and stainless steel foam.

7. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, During the electrolysis reaction, the distance between the anode plate and the cathode plate is 3~7 cm.

8. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, During the electrolysis reaction, the gas flow rate of the microbubble device is 1~4 mL / min.

9. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, The anode plate is a titanium-based coated electrode.

10. The method for recycling valuable substances and cyanide in cyanide-containing wastewater according to claim 1, characterized in that, During the electrolysis reaction, the reaction temperature is the ambient temperature, ranging from 10 to 30°C, and the reaction time is 1 to 4 hours.

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