Method and system for removing high concentration complex cyanide in gold extraction wastewater

Abstract

The application provides a method and system for removing high-concentration complex cyanide in gold extraction wastewater, and relates to the technical field of sewage treatment. The method comprises the following steps: adjusting the pH of the gold extraction wastewater to 8-10 to obtain pretreated wastewater; adding a cobalt ferrite particle catalyst to the pretreated wastewater and introducing ozone to obtain oxidized effluent; dividing the oxidized effluent into solution A and solution B according to the volume ratio, oxidizing solution A under the condition of low dissolved oxygen by using anaerobic ammonia oxidation bacteria, mixing the oxidized solution A with untreated solution B to obtain a mixed solution; and reacting the mixed solution with porous adsorption material and anaerobic ammonia oxidation bacteria, and recycling the cobalt ferrite particle catalyst for circulation. The method used by the application can effectively improve the removal rate of high-concentration complex cyanide, realizes complete mineralization of the complex cyanide, solves the core problem of difficult degradation of the complex cyanide, has strong load resistance, is simple to operate, and has good adaptability.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically to a method and system for removing high concentrations of complexed cyanide from gold extraction wastewater. Background Technology

[0002] Gold extraction wastewater (especially wastewater from cyanide gold extraction processes) contains high concentrations of cyanide, a significant portion of which is in the form of metal complex cyanides (such as [Fe(CN)6)). 3- [Cu(CN)4] 2- These complexed cyanides exist in various forms, including alkaline chlorination, hydrogen peroxide oxidation, ozone oxidation, and activated carbon adsorption. These complexed cyanides are structurally stable, highly toxic, and poorly biodegradable, making them recognized as recalcitrant pollutants. Currently, commonly used treatment methods include alkaline chlorination, hydrogen peroxide oxidation, ozone oxidation, and activated carbon adsorption, but all have significant drawbacks.

[0003] (1) Alkaline chlorination method: A large amount of chlorine-based reagents (such as chlorine gas and sodium hypochlorite) need to be added. During the reaction, highly toxic and volatile cyanogen chloride (CNCl) is easily generated, which poses a serious safety hazard. In addition, the residual chlorine and chloride ion concentration in the effluent are high, which can easily cause secondary pollution and equipment corrosion.

[0004] (2) Non-activated ozone oxidation: Ozone directly oxidizes free cyanide ions (CN). - The efficiency is acceptable, but the oxidation efficiency of highly stable metal complex cyanides is very low, the ozone utilization rate is low, and the energy consumption and operating costs are high.

[0005] (3) Homogeneous catalytic oxidation method (such as Fenton method): It needs to be operated at low pH, produces a large amount of iron sludge, and the catalyst is difficult to recover. It has limited ability to break complex cyanide and is easily affected by coexisting ions in wastewater.

[0006] (4) Adsorption method (such as activated carbon): The adsorption capacity is limited, it is easy to saturate, regeneration is difficult, and it only achieves the transfer of pollutants rather than complete degradation.

[0007] (5) Selection of activators for advanced oxidation processes (AOPs): When using persulfate (PS) for activation, a large number of sulfate ions are introduced into the system, which may cause salinity accumulation in the effluent; while when using hydrogen peroxide (H2O2) for activation, there are safety risks in its storage and transportation, and it is easily decomposed ineffectively in actual wastewater. In contrast, ozone, as an oxidant, has only oxygen as its reduction product, with no harmful ion residues, making it more environmentally friendly, but its activation efficiency is the key technology.

[0008] In view of this, the present invention is proposed. Summary of the Invention

[0009] This invention provides a method and system for removing high concentrations of complexed cyanide from gold extraction wastewater. The method used in this invention can effectively improve the removal rate of high concentrations of complexed cyanide, achieve complete mineralization of complexed cyanide, and solve the core problem of the difficult degradation of complexed cyanide. Moreover, the method and system have strong load resistance, are easy to operate, and have good adaptability.

[0010] To achieve the above-mentioned objectives of this invention, the following technical solution is adopted:

[0011] This invention provides a method for removing high concentrations of complexed cyanide from gold extraction wastewater, characterized by comprising the following steps:

[0012] S1. Adjust the pH of the gold extraction wastewater to 8-10 to obtain pretreated wastewater;

[0013] S2. Add cobalt ferrite particle catalyst to the pretreated wastewater and introduce ozone to obtain oxidized effluent;

[0014] S3. Adjust the pH of the oxidized effluent to 7, and divide the oxidized effluent into solution A and solution B by volume ratio. Use anaerobic ammonia oxidizing bacteria to oxidize solution A under conditions of low dissolved oxygen and hydraulic retention time of 1 hour. Mix the oxidized solution A with the untreated solution B to obtain a mixed solution.

[0015] S4. The mixture is reacted with porous adsorption material and anaerobic ammonia oxidizing bacteria, and the cobalt ferrite particle catalyst is recovered for recycling.

[0016] Preferably, in step S3, the volume ratio of solution A to solution B is (50-60):(40-50).

[0017] Preferably, in step S2, the concentration of ozone is 40-50 mg / L, and the reaction time is 60-90 min.

[0018] Preferably, in S3, the condition of low dissolved oxygen is: DO < 0.5 mg / L.

[0019] Preferably, in step S3, the pH of the oxidized effluent is adjusted to 8-10.

[0020] Preferably, the porous adsorbent material is a modified zeolite carrier.

[0021] Preferably, in step S2, the preparation method of the cobalt ferrite particle catalyst includes the following steps:

[0022] S201. Dissolve cobalt salt and iron salt in deionized water to obtain a mixed metal salt solution. Dissolve chitosan in acetic acid to obtain a viscous liquid. The molar ratio of cobalt to iron is 1:2.

[0023] S202. Mix the mixed metal salt solution and the viscous liquid evenly, drop them into an alkaline coagulation bath for coagulation, then transfer them to a crosslinking agent solution for crosslinking and curing, wash until neutral, and then age in ammonia water.

[0024] S203. The aged particles are calcined under controlled temperature to obtain cobalt ferrite particle catalyst.

[0025] Preferably, in step S201, the total metal ion concentration in the mixed metal salt solution is 0.5 mol / L to 2.0 mol / L.

[0026] Preferably, the volume fraction of acetic acid is 1%-3%; and the mass fraction of chitosan is 2wt%-5wt%.

[0027] Preferably, the alkaline coagulation bath is a NaOH solution with a concentration of 2 mol / L-5 mol / L; the crosslinking agent is an alcohol solution of glutaraldehyde or epichlorohydrin with a concentration of 1 wt%-3 wt%; and the crosslinking curing time is 4 h-12 h.

[0028] Preferably, the concentration of the ammonia water is 0.5 mol / L-1.0 mol / L, and the aging time is 6 h-24 h.

[0029] Preferably, the specific steps of S203 are as follows: first, the temperature is increased to 200℃-300℃ at a rate of 1℃ / min-3℃ / min, and held for 1-2 hours; then, the temperature is increased to 350℃-550℃ at a rate of 3℃ / min-5℃ / min, and held for 2-4 hours.

[0030] The present invention also provides a system for the above-mentioned method of removing high concentrations of complexed cyanide from gold extraction wastewater, comprising:

[0031] A pretreatment unit, wherein the pretreatment unit is used to adjust the pH of the gold extraction wastewater;

[0032] A catalytic ozone oxidation unit is used to activate the introduced ozone to oxidize and decompose the complexed cyanide in the wastewater;

[0033] The anaerobic ammonia oxidation denitrification unit is used to receive the effluent from the catalytic ozone oxidation unit and convert the ammonia nitrogen contained therein into nitrogen gas through anaerobic ammonia oxidation.

[0034] The pretreatment unit, the catalytic ozone oxidation unit, and the anaerobic ammonia oxidation denitrification unit are connected in sequence.

[0035] Preferably, the anaerobic ammonia oxidation denitrification unit comprises: a bypass oxygen-limited nitrification subunit and an adsorption-biofilm coupled anaerobic ammonia oxidation reactor;

[0036] The inlet of the bypass oxygen-limited nitrification subunit is connected to the outlet of the catalytic ozone oxidation unit, and is used to selectively oxidize a portion of ammonia nitrogen to nitrite; the outlet of the bypass oxygen-limited nitrification subunit is connected to the inlet of the adsorption-biofilm coupled anaerobic ammonia oxidation reactor; the adsorption-biofilm coupled anaerobic ammonia oxidation reactor is filled with porous adsorption material for adsorbing ammonia nitrogen and / or serving as a biofilm carrier for anaerobic ammonia oxidizing bacteria.

[0037] Preferably, the outlet of the adsorption-biofilm coupled anaerobic ammonia oxidation reactor is also equipped with an online monitoring instrument, which is used to adjust the bypass split ratio and the aeration rate of the oxygen-limiting nitrification unit based on real-time concentration data feedback.

[0038] Preferably, the filling amount of the porous adsorbent material is 10%-50%.

[0039] Preferably, the filling amount of the porous adsorbent material is 30%.

[0040] Preferably, the bypass oxygen-limiting nitration subunit is filled with a polyurethane sponge carrier.

[0041] The present invention also provides an application of the above-mentioned method for removing high concentrations of complexed cyanide from gold extraction wastewater in wastewater treatment.

[0042] Preferably, the wastewater is wastewater generated from the cyanide gold extraction process.

[0043] Preferably, the wastewater generated by the cyanide gold extraction process specifically refers to wastewater containing metal cyanide complexes.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] (1) The ROSs generated by the heterogeneous catalysis of ozone by cobalt ferrite particles can efficiently destroy stable metal-cyanide bonds, completely mineralize complexed cyanide into harmless substances, and make the total cyanide removal rate >93.5%.

[0046] (2) The catalyst can be magnetically separated, recovered, and reused; ozone oxidation produces no harmful byproducts; the adsorption-biofilm coupled reactor process utilizes the degradation products of pollutants themselves for biological denitrification, saving a large amount of carbon source and oxygen required by traditional nitrification and denitrification, thus saving energy consumption.

[0047] (3) By organically combining advanced chemical oxidation with cutting-edge biotechnology, a complete technology chain of "oxidation and detoxification - product resource utilization" has been formed, which has solved the bottleneck of single technology and realized the deep purification of wastewater and resource recovery.

[0048] (4) The improved adsorption-biofilm coupled reactor process has strong shock load capacity, stable operation, and a simple overall process flow, making it easy to achieve automated control. Attached Figure Description

[0049] Figure 1 Physical image and magnetic evaluation of CFS-1;

[0050] Figure 2 VSM magnetic characterization of CFS-1;

[0051] Figure 3 XRD characterization of CFS-1;

[0052] Figure 4 SEM characterization of CFS-1;

[0053] Figure 5 TEM characterization of CFS-1;

[0054] Figure 6 BET characterization of CFS-1;

[0055] Figure 7 Comparison of total cyanide removal rates between Example 1 and the three comparative examples;

[0056] Figure 8 Example 1: Comparison of ammonia nitrogen removal rates with three comparative examples;

[0057] Figure 9 EPR characterization of CFS-1;

[0058] Figure 10 Quenching experiment of CFS-1 activated ozone degrading cyanide-containing wastewater;

[0059] Figure 11 Determination of Co and Fe leaching concentrations during the degradation of cyanide-containing wastewater using CFS-1 activated ozone;

[0060] Figure 12 FTIR characterization of CFS-1 before and after 75 minutes of activated O3 degradation of cyanide-containing wastewater;

[0061] Figure 13 XPS characterization of CFS-1 before and after 75 minutes of activated O3 degradation of cyanide-containing wastewater;

[0062] Figure 14 A simplified diagram of a system for removing high concentrations of complexed cyanide from gold extraction wastewater;

[0063] Figure 15 Chemical diagram of a system for removing high concentrations of complexed cyanide from gold extraction wastewater. Detailed Implementation

[0064] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0065] Example 1

[0066] A simplified diagram of a system for removing high concentrations of complexed cyanide from gold extraction wastewater is shown below. Figure 14 As shown, the chemical diagram is as follows Figure 15 As shown, where:

[0067] 1. Wastewater inlet pipe for gold extraction; 2. Pretreatment tank; 3. Catalyst bed; 4. Ozone oxidation tank; 5. Ozone generator; 6. Catalyst recovery pipe; 7. Catalyst recovery device; 8. pH adjustment tank; 9. Flow regulating valve; 10. Bypass oxygen-limited nitrification subunit; 11. Catalytic oxidation layer; 12. Modified carrier loader; 13. Adsorption-biofilm coupled anaerobic ammonia oxidation reactor; 14. Anaerobic ammonia oxidizing bacteria loading device; 15. Intelligent monitoring device; 16.

[0068] from Figure 14 The system for removing high concentrations of complexed cyanide from gold extraction wastewater can be seen to be connected in sequence: the pretreatment unit, the catalytic ozone oxidation unit, and the anaerobic ammonia oxidation denitrification unit are connected in sequence.

[0069] The pretreatment unit is used to adjust the pH of the gold extraction wastewater.

[0070] The catalytic ozone oxidation unit is used to activate the introduced ozone and oxidize and decompose the complexed cyanide in the wastewater.

[0071] The anaerobic ammonia oxidation denitrification unit is used to receive the effluent from the catalytic ozone oxidation unit and convert the ammonia nitrogen contained therein into nitrogen gas through anaerobic ammonia oxidation.

[0072] The pretreatment unit includes: gold extraction wastewater inlet pipe 1 and pretreatment tank 2;

[0073] The catalytic ozone oxidation unit includes: catalyst bed 3, ozone oxidation tank 4, ozone generator 5, catalyst recovery pipe 6, catalyst recovery device 7, pH adjustment tank 8, flow control valve 9, and flow control valve 10.

[0074] The anaerobic ammonia oxidation denitrification unit includes: a bypass oxygen-limited nitrification subunit 11, a catalytic oxidation layer 12, a modified carrier loader 13, an adsorption-biofilm coupled anaerobic ammonia oxidation reactor 14, an anaerobic ammonia oxidation bacteria loading device 15, and an intelligent monitoring device 16.

[0075] The system works as follows:

[0076] Gold extraction wastewater enters pretreatment tank 2 through wastewater inlet pipe 1 for pH adjustment, setting the pH to 8-10. Ozone generator 5 stores ozone, which enters ozone oxidation tank 4 from the bottom via pipeline, moving upwards. Catalyst bed 3, containing millimeter-scale cobalt ferrite particles, is installed inside ozone oxidation tank 4. The pH-adjusted gold extraction wastewater enters ozone oxidation tank 4 from the top, where ozone and the pH-adjusted wastewater undergo a complete oxidation reaction before entering pH adjustment tank 8.

[0077] The oxidized wastewater enters pH adjustment tank 8 to further adjust the pH to neutral. pH adjustment tank 8 has two outlets, each equipped with a flow control valve 9 and a flow control valve 10. Flow control valves 9 and 10 control the flow rate and volume of water entering the anaerobic ammonia oxidation denitrification unit. The outlet of flow control valve 10 is directly connected to the inlet of the bypass oxygen-limited nitrification subunit 11, and the outlet of flow control valve 9 is directly connected to the outlet of the bypass oxygen-limited nitrification subunit 11. The bypass oxygen-limited nitrification subunit 11 contains a catalytic oxidation layer 12, on which anaerobic ammonia oxidizing bacteria are placed. The wastewater, adjusted to neutral, is divided into solution A and solution B in proportion by flow regulating valves 9 and 10. Solution A enters the bypass oxygen-limited nitrification subunit 11 through flow regulating valve 10 for oxidation. After oxidation, solution A is mixed with untreated solution B in the pipeline and then enters the adsorption-biofilm coupled anaerobic ammonia oxidation reactor 14.

[0078] The adsorption-biofilm coupled anaerobic ammonia oxidation reactor 14 incorporates a modified carrier loader 13 and an anaerobic ammonia oxidizing bacteria loading device 15. The mixed wastewater enters the adsorption-biofilm coupled anaerobic ammonia oxidation reactor 14 and undergoes reaction with the modified zeolite carrier and anaerobic ammonia oxidizing bacteria to complete the treatment. The adsorption-biofilm coupled anaerobic ammonia oxidation reactor 14 is externally equipped with an intelligent monitoring device to monitor the wastewater treatment process.

[0079] The ozone oxidation tank 4 is also connected to the catalyst recovery pipe 6, which is connected to the catalyst recovery device 7. The catalyst recovery device 7 has a built-in magnetic field and a washing and purification device for recycling cobalt ferrite particles.

[0080] (1) Preparation of millimeter-scale cobalt ferrite particles

[0081] Dissolve 5.82 g of Co(NO3)2·6H2O and 16.16 g of Fe(NO3)3·9H2O (Co:Fe molar ratio = 1:2) in 50 mL of deionized water to obtain a mixed metal salt solution. Dissolve 4 g of chitosan in 200 mL of 2% acetic acid solution to obtain a viscous liquid. Mix the mixed metal salt solution and the viscous liquid and stir for 2 hours. Using a 5 mL syringe (needle inner diameter 1 mm), add the mixture dropwise to a 3 mol / L NaOH solution to form brown gel spheres. Collect the particles and immerse them in an ethanol solution containing 2% glutaraldehyde for crosslinking for 8 hours. After washing with water until neutral, age them in 0.8 mol / L ammonia water for 12 hours. Collect by centrifugation, heat to 250℃ at 2℃ / min under N2 protection and hold for 2 hours, then heat to 450℃ at 4℃ / min and hold for 3 hours, and then cool naturally. Black magnetic particles with a diameter of about 2 mm to 3 mm were obtained, which are millimeter-scale cobalt ferrite particles (denoted as CFS-1).

[0082] The characterization results of the prepared millimeter-scale cobalt ferrite particles are as follows: Figures 1-6 As shown, from Figures 1-2 As can be seen, CFS-1 has good magnetic properties, with a saturation magnetization of 9.03 emu / g. The catalyst can be separated and recovered by applying an external magnetic field, making it very convenient to use.

[0083] Figures 3-5 It can be seen from the image that the synthesized substance is cobalt ferrite. Figure 3 In the XRD pattern, there are obvious peaks at 35.44° and 56.97°, which correspond to the (311) and (511) crystal planes in cobalt ferrite, respectively, indicating that the synthesized material is undoubtedly cobalt ferrite. Figure 4 Cobalt ferrite crystal particles with a distinct spinel structure can be observed in the SEM images. Figure 5 The TEM image shows a 0.260 nm lattice width band, which corresponds to the (311) crystal plane in cobalt ferrite, indicating that the cobalt ferrite catalyst was successfully synthesized.

[0084] Figure 6 The data shows that CFS-1 has a specific surface area, total pore volume, and average pore diameter of 22.44 m². 2 / g, 0.15cm 3 The α / g and 26.89nm indicate that the higher specific surface area is beneficial for adsorbing cyanide onto the catalyst surface and then catalytically degrading it.

[0085] The above preparation method utilizes chitosan as both a molding template and a carbon source, employing a "gelation-crosslinking-controlled carbonization / calcination" strategy to prepare a millimeter-scale monolithic catalyst with multi-level pores (micro-meso-macropores) in a one-step process. This structure significantly improves mass transfer efficiency, active site exposure rate, and ozone utilization.

[0086] The catalyst, cobalt ferrite (CoFe2O4), has a spinel structure, in which Co... 2+ and Fe 3+ Located at octahedral and tetrahedral sites, this multivalent structure facilitates electron transfer and efficiently catalyzes the decomposition of ozone to produce ROSs such as •OH. In the presence of cobalt ferrite catalyst, ozone can be efficiently activated to generate hydroxyl radicals (•OH) and superoxide radicals (•O2). - ), singlet oxygen and other ROSs, completely oxidize and decompose complexed cyanide into carbonate (CO3). 2- ), nitrogen (N2) and ammonium ions (NH4) + SO4 was avoided. - • The problem of increased salinity due to limited selective attack and residual sulfate ions.

[0087] Meanwhile, the heterogeneous catalyst is easy to separate and recover (magnetic), exhibits extremely low metal ion dissolution (experiments confirm Co / Fe dissolution concentration <0.1 mg / L), and demonstrates good stability. The millimeter-sized monolithic particles avoid the drawbacks of powdered catalysts, such as easy loss and difficulty in recovery, and can be directly packed into fixed-bed reactors, simplifying operation.

[0088] (2) Catalytic ozone oxidation treatment of simulated gold extraction wastewater

[0089] Prepare a 500 mg / L solution containing K3[Fe(CN)6] (using CN... - (Calculation), Cu 2+ Simulated wastewater with a concentration of 100 mg / L and a pH of 9.5.

[0090] S1. In the pretreatment unit, the pH of the wastewater is adjusted to 8-10 (in this embodiment, the pH is adjusted to 9) to obtain pretreated wastewater;

[0091] S2. Design of the catalytic ozone oxidation unit: A 500mL self-made glass reactor was used, containing 50g of CFS-1 granules, which were then placed in a fixed bed. Pretreated wastewater was passed through an oxygen stream containing 40mg / L ozone at a flow rate of 0.5L / min for 75 minutes to obtain oxidized effluent. Test results showed a total cyanide removal rate of 93.5%, and the effluent NH4... + -N concentration ~120mg / L (consistent with theoretical value), Co / Fe leaching concentrations are both below 0.1mg / L.

[0092] S3. Use the above-mentioned oxidized effluent (adjusted to pH 7) as the feed water. The total feed water contains NH4+. + The content of -N is 120 mg / L.

[0093] A bypass oxygen-limiting nitrification subunit (filled with a polyurethane sponge carrier) was set up, with a DO concentration of approximately 0.3 mg / L and a hydraulic retention time (HRT) of 4 h. The oxidized effluent was divided into solution A and solution B, with solution A having a flow rate of 55% and solution B having a flow rate of 45%. Solution A entered the bypass oxygen-limiting nitrification subunit, at which point approximately 50% of the NH4+ in the oxidized effluent was obtained. + Converted to NO2 - The oxidized solution A is mixed with solution B, so that the mixture contains NH4. + -N ≈ 85mg / L, NO2 - -N ≈ 18 mg / L (close to the theoretical ratio of 1.32:1 for NH4) + (Rest). The mixed liquor enters an adsorption-biofilm coupled anaerobic ammonia oxidation reactor (containing 30% volume of modified zeolite carrier and mature anaerobic ammonia oxidizing bacteria with attached biofilm), HRT=12h. After the system has been running stably for 10 days, the effluent NH4... + -N = 2.8 mg / L, NO2 - -N = 0.5 mg / L, ammonia nitrogen removal rate = 97.6%. The system exhibits good stability.

[0094] Adding porous adsorbent materials (such as modified zeolite or biochar) or directly using a small amount of deactivated but porous cobalt ferrite particles separated from the oxidation unit as a biofilm carrier in an adsorption-biofilm coupled reactor allows anaerobic ammonia-oxidizing bacteria to preferentially attach to and grow within the pores of the carrier, forming a dense biofilm. The carrier is effective against NH4+. + The adsorption effect can buffer and enrich the microorganisms when the influent load fluctuates, providing a relatively stable substrate environment for the microorganisms and improving the system's resistance to shocks.

[0095] Because the effluent from catalytic oxidation contains almost no organic carbon, and NH4 + High concentration, but lacking NO2 - This invention employs a bypass oxygen-limiting nitration subunit to convert approximately 50%-60% of NH4+ into oxygen. + The flow is diverted to a compact aerobic biofilm reactor, where, under strictly controlled low dissolved oxygen (DO < 0.5 mg / L) and short hydraulic retention time, anaerobic ammonia-oxidizing bacteria (AOB) selectively oxidize it to NO2. - This inhibits the growth of nitrite-oxidizing bacteria (NOB). Then, NO2-rich... - nitrification liquid and remaining NH4-rich + The effluent from oxidation is stoichiometric according to the theoretical stoichiometric ratio (NO2)- :NH4 + The mixture (approximately 1.32:1) is then fed into an adsorption-biofilm coupled reactor. This strategy achieves the desired NH4+ concentration. + This allows for in-situ, on-demand conversion of the substrates required by anaerobic ammonia oxidizing bacteria, avoiding the costs, environmental, and safety risks associated with purchasing nitrites from external sources.

[0096] Comparative Example 1: Ozone Oxidation Only

[0097] Procedure: The same simulated wastewater was subjected to ozone oxidation under conditions identical to that of Example 1, without the addition of any catalyst. The ozone dosing conditions (concentration, flow rate, time) were strictly maintained as in Example 1. No subsequent experimental steps were performed.

[0098] Comparative Example 2: Comparison of Cobalt Ferrate-Activated Persulfate

[0099] Solution: Use the same batch of CFS-1 granules (50g) as catalyst to treat the same simulated wastewater in the same reactor. Replace ozone with an equivalent amount of sodium persulfate (Na2S2O8) and activate it by heating (60℃).

[0100] Comparative Example 3: Comparison of Traditional Biochemical Nitrogen Removal Processes

[0101] Solution: Take the effluent (NH4) from the catalytic ozone oxidation unit of Example 1. + The influent (NH4+ ~120 mg / L) is treated using a traditional activated sludge process of "complete nitrification-denitrification". The nitrification stage requires sufficient aeration to remove NH4+. + Oxidized to NO3 - In the denitrification stage, methanol needs to be added as an organic carbon source according to the stoichiometric ratio (C / N≈3-4).

[0102] Experimental Example 1: Performance Comparison of Catalysts with Different Cobalt-Iron Molar Ratios

[0103] Experimental objective: To verify the optimal composition of the catalyst.

[0104] Preparation: Following the method in Example 1, with the calcination temperature fixed at 450℃, the cobalt iron salt addition ratio was changed to prepare catalyst particles with Co:Fe molar ratios of 1:1 (CFS-2), 1:1.5 (CFS-3), 1:2 (CFS-1, control), 1:2.5 (CFS-4), and 1:3 (CFS-5).

[0105] Test: Tested under the same conditions (50g catalyst, 40mg / L ozone, treatment of 500mg / L complexed cyanide wastewater for 75 minutes).

[0106] The experimental results are shown in Table 1.

[0107] Table 1: Optimal Cobalt-Iron Molar Ratio for Catalysts

[0108]

[0109] It is evident that a Co:Fe ratio of 1:2 is the preferred ratio.

[0110] Experiment Example 2: Performance Test of Simulated Wastewater Treatment with Complex Components

[0111] Experimental objective: To simulate wastewater composition that more closely resembles actual working conditions and to examine the performance of catalysts in treating water bodies with complex components.

[0112] Wastewater composition: except for K3[Fe(CN)6] (in CN) - In addition to 500 mg / L, Cu was added. 2+ 50 mg / L, Zn 2+ 30 mg / L, Au(CN) 2- (5 mg / L as Au), total salinity approximately 5000 mg / L, pH=9.0.

[0113] Oxidation unit operation: 50g of CFS-1 granules were packed into a continuous flow fixed-bed reactor (2cm in diameter, 20cm in height). Wastewater flowed upwards at a rate of 1L / h, while ozone was introduced from the bottom (concentration 50mg / L, gas flow rate 0.3L / min). The system operated continuously for 240 hours (10 days).

[0114] Treatment effect: After the system stabilizes, the total cyanide removal rate is around 90%, and NH4 removal rate is also low. + -N generation is stable in the range of 115 mg / L-125 mg / L.

[0115] Experimental Example 3: Comparison of total cyanide removal rates after 75 minutes of catalytic degradation between Example 1 and three comparative examples.

[0116] The concentration of cyanide ions was determined using the isonicotinic acid-pyrazolone spectrophotometric method. Approximately 3 mL of the catalytically degraded solution was placed in a cuvette, and the absorbance was measured at 638 nm using a spectrophotometer. The absorbance was then converted to the corresponding concentration.

[0117] Experimental results are as follows Figure 7 As shown, the total cyanide removal rates of Example 1 and Comparative Examples 1, 2, and 3 were 93.5%, 36.1%, 81.8%, and 91.2%, respectively, indicating that Example 1 had the best total cyanide removal capacity.

[0118] Experimental Example 4: Comparison of ammonia nitrogen removal rates after 75 minutes of catalytic degradation between Example 1 and three comparative examples.

[0119] Ammonia nitrogen concentration was measured spectrophotometrically. A suitable amount of the catalytically degraded solution (3-5 mL) was taken and the absorbance was measured in a Hach DR5000 spectrophotometer, then converted to the corresponding concentration.

[0120] Experimental results are as follows Figure 8 As shown, from Figure 8 It can be seen that the removal rates of ammonia nitrogen in Example 1 and Comparative Examples 1, 2 and 3 were 97.6%, 91.8%, 85.1% and 75.0%, respectively, indicating that Example 1 has the best effect in removing ammonia nitrogen.

[0121] Experiment Example 5: EPR Test ROSs

[0122] The CFS-1 catalyst was reacted with 1 mM 5,5-dimethyl-1-pyrrolidone-N-oxide (DMPO) and 2,2,6,6-tetramethyl-4-piperidinone (TEMP), respectively, and the types of reactive oxygen species generated were determined by electron paramagnetic resonance spectroscopy at 1 min.

[0123] Experimental results are as follows Figure 9 As shown in the figure, three types of free radicals ( ) can be observed during the degradation of cyanide-containing wastewater by CFS-1 activated ozone. 1 O2、·O - 2. Both ·OH) are present.

[0124] Experiment Example 6: Quenching Experiment of CFS-1 Activated Ozone Degradation of Cyanide-Containing Wastewater

[0125] Adding 2 mM β-carotene, tert-butanol, and p-benzoquinone to the CFS-1 activated ozone degradation process of cyanide-containing wastewater yields... Figure 10 The results show that β-carotene, tert-butanol, and p-benzoquinone correspond to the quenching of singlet oxygen (…). 1 O2), hydroxyl radicals (·OH), and superoxide radicals (·O) - 2) By Figure 10 It can be seen that the dominant active oxygen species in the process of CFS-1 activated ozone degradation of cyanide-containing wastewater is... 1 O2.

[0126] Experimental Example 7: Determination of Co and Fe leaching concentrations during the degradation of cyanide-containing wastewater by CFS-1 activated ozone

[0127] The water sample from Example 1, after degradation for 75 minutes, was analyzed by ICP-MS to determine the concentrations of dissolved Co and Fe elements in the solution. The experimental results are as follows: Figure 11 As shown, after 75 minutes of activated O3 degradation of cyanide-containing wastewater, the leaching concentrations of Co and Fe by CFS-1 were 0.08 mg / L and 0.035 mg / L, respectively, both below 0.1 mg / L, indicating that the catalyst has good stability and environmental friendliness.

[0128] Experimental Example 8: FTIR characterization of CFS-1 catalyst before and after 75 minutes of O3 activation for cyanide-containing wastewater degradation

[0129] Experimental results are as follows Figure 12 As shown, the FTIR characterization revealed that the position and intensity of the peaks in the CFS-1 catalyst did not shift or weaken significantly before and after 75 minutes of O3 activation to degrade cyanide-containing wastewater, indicating that the catalyst has good stability.

[0130] Experimental Example 9: XPS characterization of CFS-1 catalyst before and after 75 minutes of O3 activation for cyanide-containing wastewater degradation

[0131] Experimental results are as follows Figure 13 As shown, XPS characterization of the CFS-1 catalyst before and after 75 minutes of O3 activation for cyanide-containing wastewater degradation revealed that the positions and intensities of the Co and Fe peaks did not change significantly, indicating that the CFS-1 catalyst has good structural stability and great potential for practical application.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for removing high concentrations of complexed cyanide from gold extraction wastewater, characterized in that, Includes the following steps: S1. Adjust the pH of the gold extraction wastewater to 8-10 to obtain pretreated wastewater; S2. Add cobalt ferrite particle catalyst to the pretreated wastewater and introduce ozone to obtain oxidized effluent; S3. Adjust the pH of the oxidized effluent to 7, and divide the oxidized effluent into solution A and solution B by volume ratio. Use anaerobic ammonia oxidizing bacteria to oxidize solution A under conditions of low dissolved oxygen and hydraulic retention time of 1 hour, selectively oxidizing some ammonia nitrogen to nitrite. Mix the oxidized solution A with the untreated solution B to obtain a mixed solution. S4. The mixture is reacted with porous adsorption material and anaerobic ammonia oxidizing bacteria, and the cobalt ferrite particle catalyst is recovered for recycling. In step S2, the preparation method of the cobalt ferrite particle catalyst includes the following steps: S201. Dissolve cobalt salt and iron salt in deionized water to obtain a mixed metal salt solution. Dissolve chitosan in acetic acid to obtain a viscous liquid. The molar ratio of cobalt to iron is 1:

2. S202. Mix the mixed metal salt solution and the viscous liquid evenly, drop them into an alkaline coagulation bath for coagulation, then transfer them to a crosslinking agent solution for crosslinking and curing, wash until neutral, and then age in ammonia water. S203. The aged particles are calcined under controlled temperature to obtain cobalt ferrite particle catalyst.

2. The method for removing high concentrations of complexed cyanide from gold extraction wastewater according to claim 1, characterized in that, In S3, the volume ratio of solution A to solution B is (50-60):(40-50).

3. The method for removing high concentrations of complexed cyanide from gold extraction wastewater according to claim 1, characterized in that, In S2, the ozone concentration is 40-50 mg / L, and the reaction time is 60-90 min.

4. The method for removing high concentrations of complexed cyanide from gold extraction wastewater according to claim 1, characterized in that, In S3, the specific condition for low dissolved oxygen is: DO < 0.5 mg / L.

5. The method for removing high concentrations of complexed cyanide from gold extraction wastewater according to claim 1, characterized in that, The specific steps of S203 are as follows: first, heat the temperature to 200℃-300℃ at a rate of 1℃ / min-3℃ / min and hold for 1-2 hours; then heat the temperature to 350℃-550℃ at a rate of 3℃ / min-5℃ / min and hold for 2-4 hours.

6. A system for removing high concentrations of complexed cyanide from gold extraction wastewater, characterized in that, The system applied to the method for removing high concentrations of complexed cyanide from gold extraction wastewater according to any one of claims 1-5, the system comprising: A pretreatment unit, wherein the pretreatment unit is used to adjust the pH of the gold extraction wastewater; A catalytic ozone oxidation unit is used to activate the introduced ozone to oxidize and decompose the complexed cyanide in the wastewater; An anaerobic ammonia oxidation denitrification unit is used to receive the effluent from the catalytic ozone oxidation unit and convert the ammonia nitrogen contained therein into nitrogen gas through anaerobic ammonia oxidation. The pretreatment unit, the catalytic ozone oxidation unit, and the anaerobic ammonia oxidation denitrification unit are connected in sequence.

7. The system for removing high concentrations of complexed cyanide from gold extraction wastewater according to claim 6, characterized in that, The anaerobic ammonia oxidation denitrification unit includes: a bypass oxygen-limited nitrification subunit and an adsorption-biofilm coupled anaerobic ammonia oxidation reactor; The inlet of the bypass oxygen-limited nitrification subunit is connected to the outlet of the catalytic ozone oxidation unit, and is used to selectively oxidize a portion of ammonia nitrogen to nitrite; the outlet of the bypass oxygen-limited nitrification subunit is connected to the inlet of the adsorption-biofilm coupled anaerobic ammonia oxidation reactor; the adsorption-biofilm coupled anaerobic ammonia oxidation reactor is filled with porous adsorption material for adsorbing ammonia nitrogen and / or serving as a biofilm carrier for anaerobic ammonia oxidizing bacteria.

8. The application of a method for removing high concentrations of complexed cyanide from gold extraction wastewater as described in any one of claims 1-5 or a system for removing high concentrations of complexed cyanide from gold extraction wastewater as described in any one of claims 6-7 in wastewater treatment.

9. The application according to claim 8, characterized in that, The wastewater specifically includes wastewater generated from the cyanide gold extraction process.

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