Method for degrading gold cyanidation tailings by utilizing aluminum-based bimetallic catalyst photo-Fenton

Abstract

The invention discloses a method for degrading gold cyanidation tailings through photo-Fenton of an aluminum-based bimetallic catalyst, and belongs to the technical field of cyanidation tailings treatment. Iron salt and zinc salt are loaded on activated aluminum oxide through an impregnation method, the aluminum-based bimetallic catalyst is obtained through the treatment processes of roasting, grinding, drying and the like, and iron oxide and zinc ferrite contained in the synthesized aluminum-based bimetallic catalyst are main active substances for degrading cyanide residues through photo-Fenton catalysis; under the participation of hydrogen peroxide and an ultraviolet light source, the concentration of cyanide in the cyanide residues can be remarkably reduced, toxicity detection on the reacted filter residues shows that the concentration of the cyanide is lower than the national standard, and the cyanide residues can be treated as general solid waste; the cyanide removal rate can reach 95% or above, and the method has a very good application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of cyanide tailings treatment, and particularly relates to a method for photocatalytic Fenton degradation of gold cyanide tailings by using an aluminum-based bimetallic catalyst. Background Art

[0002] As a highly toxic substance, a large number of literature reports have been made on the related research of its degradation and removal, and some de-cyanidation technologies have been widely applied in the gold industry. However, in the existing cyanide removal technologies, there are certain deficiencies in the efficient degradation technologies for total cyanide in cyanide tailings in actual industrial production. For example, the acidification method has the risk of hydrogen cyanide gas leakage; membrane fouling and expensive cleaning or regeneration costs in the membrane separation method; the complexation precipitation method has high requirements for the consumption of reagents and pH value; the alkaline chlorination method requires an additional residual chlorine collection device and the equipment is easily corroded; the biological method has poor microbial tolerance and a long treatment cycle. Therefore, at present, there is a need to develop a harmless treatment technology for gold cyanide tailings with broad prospects, economic efficiency, and environmental friendliness to prevent it from causing harmful effects on humans and animals. Among all the advanced oxidation processes, the photocatalytic Fenton process is a clean and efficient method for treating cyanide tailings.

[0003] Different from the traditional Fenton oxidation process, the photocatalytic Fenton process is no longer limited to the reaction between Fe 2+ and hydrogen peroxide, which provides a feasible way for various free radicals to participate in the degradation of cyanide. Jiang Xigen (Research on the treatment of cyanide-containing wastewater by UV-ozone-activated carbon combined method [J]. Environmental Science and Management, 2020, 45(11): 127-129.) used the UV-ozone-activated carbon combined method to treat cyanide-containing wastewater and explored the content of activated carbon, ozone concentration, light irradiation time and intensity. It was found that activated carbon can use its spatial structure to adsorb cyanide, shorten the distance to generate hydroxyl radicals with ozone, and accelerate the reaction rate; with the assistance of ultraviolet light, it plays a coupled synergistic role in reaction separation, and the effect is greatly improved. When the O3 flow rate is 35mg·min -1 ·L -1, when the ultraviolet irradiation band is 200 - 275 nm and the activated carbon dosage is 10 g / L, the cyanide removal rate can reach 93% in 30 min. Although the above method has a relatively high cyanide removal rate, the process is complex. Not only is the O3 generator not easy to implement in actual production, but also the cost is relatively high. Wang Erli (Research on the Chemical Kinetics of Photolysis of Cyanide in Cyanide-Containing Wastewater [J]. Journal of Liaoning Technical University (Natural Science Edition), 2001, (01): 121 - 124.) et al. used simulation experimental methods to study the chemical kinetics and photolysis results of cyanide photolysis in wastewater under sunlight irradiation. The results showed that the photolysis removal rate of total cyanide in wastewater was 49.4% - 56.9%. The above research only used sunlight irradiation, and the intensity of the radiation wavelength and frequency was relatively low, resulting in a low photo-removal rate of cyanide. Wu Xiaofei (Photocatalytic Degradation of Free Cyanide by TiO2-PW9 Composite Catalyst [J]. Acta Scientiae Circumstantiae, 2019, 39(11): 3802 - 3810. DOI: 10.13671 / j.hjkxxb.2019.0208.) et al. prepared a TiO2-PW9 composite catalyst by hydrothermal method and studied its photocatalytic degradation effect on free cyanide. The results showed that when the initial CN - concentration was 0.3 mmol / L and the catalyst dosage was 1 g / L, the photocatalytic activity of the composite catalyst was the best. After 150 min of reaction, the removal rate of CN - reached 81%. Although the above research prepared a composite catalyst and had a certain effect on the photocatalytic degradation of cyanide under appropriate conditions, the removal rate was not high, there was still some cyanide residue in the residual liquid, and the conditions such as the dosage of reagents and the reaction time in the experiment were relatively large, resulting in an increase in cost in actual production. Summary of the Invention

[0004] Aiming at the defects such as long process, high cost, and low de-cyanidation efficiency in the process of photocatalytic degradation of cyanide in the prior art, the purpose of the present invention is to provide a method for photocatalytic Fenton degradation of gold cyanidation tailings by using an aluminum-based bimetallic catalyst. The iron oxide and zinc ferrite contained in the synthesized catalyst are the main active substances for photocatalytic Fenton degradation of cyanide tailings. With the participation of hydrogen peroxide and ultraviolet light source, the cyanide concentration in the cyanide tailings can be significantly reduced. After the reaction, the filter residue is detected for toxicity, and the cyanide concentration is lower than the national standard and can be treated as general solid waste; the cyanide removal rate can reach more than 95%, and it has a very good application prospect.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] In the first aspect, the present invention provides a preparation method of an aluminum-based bimetallic catalyst, including the following steps:

[0007] (1) Add an aluminum compound to an acid solution for impurity removal by soaking, wash with water 1 - 5 times, and obtain activated alumina after drying.

[0008] (2) Dissolve an iron salt and a zinc salt in distilled water, add the activated alumina obtained in step (1) and mix evenly. Control the molar ratio of aluminum to zinc in the activated alumina to be 1:0.01 - 1:0.4, and the molar ratio of aluminum to iron in the activated alumina to be 1:0.01 - 1:0.30.

[0009] (3) Stir the mixture obtained in step (2) for 6 - 24 h under the conditions of a temperature of 40 - 80 °C and a stirring speed of 100 - 1000 rpm, and then calcine at 300 - 950 °C for 2 - 10 h to obtain a precursor of an aluminum-based bimetallic catalyst.

[0010] (4) Grind the precursor of the aluminum-based bimetallic catalyst obtained in step (3) into powder, and then obtain the aluminum-based bimetallic catalyst after drying and using a constant-temperature drying oven.

[0011] Based on the above technical solution, further, the aluminum compound described in step (1) is selected from alumina or aluminum hydroxide, preferably γ-Al2O3.

[0012] Based on the above technical solution, further, the acid solution in step (1) is concentrated nitric acid with a concentration of 2 - 10 mol / L, and the soaking time is 3 - 24 h.

[0013] Based on the above technical solution, further, the drying temperature in step (1) is 105 - 150 °C, the drying time is 12 - 36 h, and the pH range after drying is 4.5 - 6.5.

[0014] Based on the above technical solution, further, the iron salt in step (2) is nitrate, sulfate, chloride, acetate of iron and their hydrates, and the zinc salt is nitrate, sulfate, chloride, acetate of zinc and their hydrates.

[0015] Based on the above technical solution, further, control the molar ratio of aluminum to zinc in the activated alumina in step (2) to be 1:0.10 - 1:0.3, and the molar ratio of aluminum to iron in the activated alumina to be 1:0.03 - 1:0.25.

[0016] Based on the above technical solution, further, the calcination temperature in step (3) is 500 - 950 °C, and the calcination time is 2 - 6 h.

[0017] Based on the above technical solution, further, the drying temperature in step (4) is 80 - 110 °C, the drying time is 1 - 12 h, the temperature of constant-temperature drying is 60 - 80 °C, and the drying time is 10 - 24 h.

[0018] In a second aspect, the present invention also provides an aluminum-based bimetallic catalyst prepared by the above preparation method.

[0019] In a third aspect, the present invention also provides a method for photocatalytic Fenton degradation of gold cyanidation tailings by using the above aluminum-based bimetallic catalyst, comprising the following steps:

[0020] 1) Adding the cyanidation tailings to deionized water to make a pulp with a mass concentration of 10-40%, and adjusting the pH value to 6.5-8.5 to obtain a slurry;

[0021] 2) Adding the aluminum-based bimetallic catalyst and hydrogen peroxide to the slurry obtained in step 1), and stirring for 30-180 min under the conditions of a temperature of 30-80 °C, a stirring speed of 100-500 rpm, and irradiation with an ultraviolet light source;

[0022] 3) Filtration: Filtering the reaction material obtained in step 2) with a filter press to obtain filter residue and filtrate.

[0023] Based on the above technical solution, further, the content of cyanide in the cyanidation tailings in step 1) is 1000-1500 mg / kg.

[0024] Based on the above technical solution, further, the addition amount of the catalyst in step 2) is 1-10 g / L of the pulp, the addition amount of hydrogen peroxide is 2-30 g / L of the pulp, and the mass percentage concentration of hydrogen peroxide is 3%-30%.

[0025] Based on the above technical solution, further, the wavelength of the ultraviolet light source in step 2) is 250-255 nm, and the light intensity is 10-400 μW / cm 2 .

[0026] Based on the above technical solution, further, the degradation rate of cyanide in the cyanidation tailings reaches more than 95%.

[0027] The beneficial effects of the present invention compared with the prior art are as follows:

[0028] (1) The catalyst of the present invention has a low cost. All iron-containing compounds, zinc-containing compounds, and alumina carriers are common experimental raw materials, which are convenient to obtain, have a short preparation process, and mild preparation conditions.

[0029] (2) Compared with the existing catalytic systems, the catalyst synthesized in the present invention contains two active substances, Fe2O3 and ZnFe2O4, which can play a synergistic effect of Fenton-like and photocatalysis in photocatalytic Fenton, further improving the catalyst cycle stability and the degradation ability of cyanide; the catalyst preparation by the impregnation method has a simple process, low cost, and is convenient for large-scale industrial applications; at the same time, in the process of treating gold cyanidation tailings by the photocatalytic Fenton oxidation process, the reaction conditions are mild, the by-products are few, clean and pollution-free; the process route is short, the operation is simple, and the energy consumption is small; it has broad industrial application prospects in the field of gold hazardous waste treatment.

[0030] (3) The present invention has a high de-cyanation rate, and the cyanide removal rate can reach more than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings related to the embodiments will be briefly introduced below.

[0032] Figure 1 XRD patterns of the aluminum-based bimetallic catalysts prepared in Examples 1-3.

[0033] Figure 2 500-fold scanning electron microscope (SEM-EDS) images of the aluminum-based bimetallic catalysts prepared in Examples 1-3.

[0034] Figure 3 5000-fold scanning electron microscope (SEM-EDS) images of the aluminum-based bimetallic catalysts prepared in Examples 1-3.

[0035] Figure 4 Elemental mapping images of the aluminum-based bimetallic catalysts prepared in Examples 1-3 by scanning electron microscope (SEM-EDS). DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The present invention will be described in detail below in conjunction with the embodiments. However, the embodiments of the present invention are not limited thereto. Obviously, the embodiments described below are only part of the embodiments of the present invention. For those skilled in the art, without creative efforts, obtaining other similar embodiments will fall within the protection scope of the present invention.

[0037] Example 1

[0038] This example provides a preparation method of an aluminum-based bimetallic catalyst, including the following steps:

[0039] (1) Weigh 50 g of analytical pure γ-Al2O3, add it to an 8 mol / L concentrated nitric acid solution, let it stand for 12 h for impurity removal, then wash it twice with distilled water, and then dry it at 120 °C for 24 h and measure its pH to be 6.0 to obtain activated alumina for use;

[0040] (2) Weigh 14.85 g of analytical pure ferric nitrate nonahydrate and 21.86 g of zinc nitrate hexahydrate, add them to distilled water and mix them until completely dissolved. Then mix them with 50 g of the activated alumina prepared in step (1), and control the molar ratio of aluminum element to zinc in the activated alumina sample to be 1:0.15; the molar ratio of aluminum element to iron to be 1:0.075;

[0041] (3) Control the temperature of the mixture in step (2) in a constant temperature water bath at 60 °C, with a magnetic stirring speed of 200 rpm and a stirring time of 12 h;

[0042] (4) Place the substance prepared in step (3) in a muffle furnace and calcine it at 950 °C for 5 h to obtain the precursor of the aluminum-based bimetallic catalyst;

[0043] (5) First grind the precursor of the aluminum-based bimetallic catalyst prepared in step (4) into a powder, then dry it in a vacuum drying oven at 105 °C for 12 h, and finally treat it in a constant temperature drying oven at 80 °C for 24 h to obtain the aluminum-based bimetallic catalyst;

[0044] The catalyst prepared in this example has a large specific surface area and strong adsorption ability, and can effectively adsorb free cyanide and metal cyanide in the cyanidation tailing slurry; the prepared aluminum-based bimetallic catalyst is subjected to XRD detection and scanning electron microscopy detection, and it is found that the main components are Fe2O3, ZnO and ZnFe2O4, etc. ( Figures 1-4 ), and the catalyst contains two active substances, Fe2O3 and ZnFe2O4, which can play a synergistic effect of Fenton-like and photocatalysis in photocatalytic Fenton, further improving the degradation ability of cyanide in gold cyanide slag while also improving the recycling stability of the catalyst in the photocatalytic system.

[0045] Example 2

[0046] This example provides a preparation method of an aluminum-based bimetallic catalyst, including the following steps:

[0047] (1) Weigh 50 g of analytical pure γ-Al2O3, add it to an 8 mol / L concentrated nitric acid solution, let it stand for 8 h for impurity removal, then wash it once with distilled water, and then dry it at 105 °C for 12 h and measure its pH to be 6.5 to obtain the activated alumina for use;

[0048] (2) Weigh 29.7 g of analytical pure ferric nitrate nonahydrate and 43.72 g of zinc nitrate hexahydrate, add them to distilled water and mix them until completely dissolved. Then mix them with 50 g of the activated alumina substance prepared in step (1), and control the molar ratio of aluminum element to zinc in the activated alumina sample to be 1:0.3; the molar ratio of aluminum element to iron to be 1:0.15;

[0049] (3) The mixture in step (2) is temperature-controlled in a constant-temperature water bath, with the temperature controlled at 55 °C, the magnetic stirring speed at 250 rpm, and the stirring time at 6 h;

[0050] (4) The substance obtained in step (3) is calcined in a muffle furnace at a temperature of 550 °C for 3 h to obtain a precursor of the aluminum-based bimetallic catalyst;

[0051] (5) The precursor of the aluminum-based bimetallic catalyst obtained in step (4) is first ground into a powder, then dried in a vacuum drying oven at a temperature of 110 °C for 6 h, and finally treated in a constant-temperature drying oven at 60 °C for 12 h to obtain the aluminum-based bimetallic catalyst;

[0052] The prepared aluminum-based bimetallic catalyst was subjected to XRD detection and found that the main components were Fe2O3, ZnO, and ZnFe2O4, etc. ( Figure 1 ).

[0053] Example 3

[0054] This example provides a method for preparing an aluminum-based bimetallic catalyst, including the following steps:

[0055] (1) Weigh 50 g of analytical pure γ-Al2O3, add it to an 8 mol / L concentrated nitric acid solution, let it stand for 9 h for impurity removal, then wash it 3 times with distilled water, and then dry it at 140 °C for 18 h and measure its pH to be 5.5 to obtain activated alumina for use;

[0056] (2) Weigh 39.59 g of analytical pure ferric nitrate nonahydrate and 36.44 g of zinc nitrate hexahydrate, add distilled water and mix them. After complete dissolution, mix them with 50 g of the activated alumina substance prepared in step (1), and control the molar ratio of aluminum element to zinc in the activated alumina sample to be 1:0.25; the molar ratio of the aluminum element to iron is 1:0.2;

[0057] (3) The mixture in step (2) is temperature-controlled in a constant-temperature water bath, with the temperature controlled at 70 °C, the magnetic stirring speed at 450 rpm, and the stirring time at 24 h;

[0058] (4) The substance obtained in step (3) is calcined in a muffle furnace at a temperature of 850 °C for 6 h to obtain a precursor of the aluminum-based bimetallic catalyst;

[0059] (5) The precursor of the aluminum-based bimetallic catalyst obtained in step (4) is first ground into a powder, then dried in a vacuum drying oven at a temperature of 85 °C for 2 h, and finally treated in a constant-temperature drying oven at 70 °C for 18 h to obtain the aluminum-based bimetallic catalyst;

[0060] The prepared aluminum-based bimetallic catalyst was subjected to XRD detection, and it was found that the main components were Fe2O3, ZnO, ZnFe2O4, etc.( Figure 1 ).

[0061] Example 4

[0062] The aluminum-based bimetallic catalyst synthesized in Example 1 was applied to the photo-Fenton catalytic oxidation treatment of gold cyanidation tailings, including the following steps:

[0063] (1) Gold cyanidation tailings with a cyanide content of 1358 mg / kg were added to deionized water to make a pulp with a mass concentration of 10%;

[0064] (2) The pH value of the pulp was adjusted to 6.5 with sodium hydroxide to make a slurry;

[0065] (3) The pulp obtained in step (2) was poured into a conical flask, and the catalyst and hydrogen peroxide (mass percentage concentration of 30%) were added in a certain proportion. The addition amount of hydrogen peroxide was 6 g per liter of pulp, and the addition amount of the catalyst was 2.5 g per liter of pulp. Then the conical flask was placed in a constant-temperature magnetic stirring water bath device (temperature controlled at 60 °C, stirring speed of 300 rpm), and the height of the ultraviolet light source (ultraviolet light wavelength 253.7 nm) was adjusted to make the light in the bottle fully uniform, and the light intensity was 70 μW / cm 2 . During this period, prevent a large amount of bubbles from overflowing due to heat release in the bottle, and the reaction time was 60 min.

[0066] (4) Filtration: The reaction material was filtered with a filter press to obtain filter residue and filtrate.

[0067] (5) Detection: The filter residue was subjected to toxicity detection (HJ / 299-2007 "Solid Waste Toxicity Leaching Method Sulfuric Acid-Nitric Acid Method" and HJ484-2009 "Determination of Cyanide in Water Titrimetric Method and Sub-Spectral Photometric Method"), and the cyanide concentration was found to be 4 mg / L, which was lower than the national standard (HJ943-2018 "Technical Specification for Pollution Control of Cyanide Residues in the Gold Industry"), meeting the discharge standard and being directly discharged. That is, the cyanide concentration of the original cyanidation tailings was reduced to 40 mg / kg, and the degradation rate of cyanide in the cyanidation tailings reached 97.05%.

[0068] Example 5

[0069] The aluminum-based bimetallic catalyst synthesized in Example 2 was applied to the photo-Fenton catalytic oxidation treatment of gold cyanidation tailings, including the following steps:

[0070] (1) Gold cyanidation tailings with a cyanide content of 1358 mg / kg were added to deionized water to make a pulp with a mass concentration of 20%;

[0071] (2) The pH value of the pulp was adjusted to 7.0 with sodium hydroxide to make a slurry;

[0072] (3) Pour the pulp obtained in step (2) into a conical flask, add a catalyst and hydrogen peroxide (mass percentage concentration is 20%) in a certain proportion. The addition amount of hydrogen peroxide is 10 g per liter of pulp, and the addition amount of the catalyst is 3.5 g per liter of pulp. Then place the conical flask in a constant temperature magnetic stirring water bath device (temperature controlled at 50 °C, stirring speed is 200 rpm) and adjust the height of the ultraviolet light source (ultraviolet light wavelength 253.7 nm) to make the light in the flask fully and evenly distributed, and the light intensity is 107 μW / cm 2 . During this period, prevent a large amount of bubbles from overflowing due to heat release in the flask, and the reaction time is 90 min.

[0073] (4) Filtration: Filter the reaction material with a filter press to obtain filter residue and filtrate.

[0074] (5) Detection: The filter residue is detected by toxicity tests (HJ / 299 - 2007 "Solid Waste Toxicity Leaching Method - Sulfuric Acid and Nitric Acid Method" and HJ484 - 2009 "Determination of Cyanide in Water - Titrimetric Method and Separation Photometric Method"), indicating that the cyanide concentration is 3 mg / L, lower than the national standard (HJ943 - 2018 "Technical Specification for Pollution Control of Cyanide Residue in the Gold Industry"), meeting the discharge standard and being directly discharged. That is, the cyanide concentration in the original cyanidation tailings is reduced to 30 mg / kg, and the degradation rate of cyanide in the cyanidation tailings is 97.79%.

[0075] Example 6

[0076] Apply the aluminum-based bimetallic catalyst synthesized in Example 3 to the photo-Fenton catalytic oxidation treatment of gold cyanidation tailings, including the following steps:

[0077] (1) Add gold cyanidation tailings with a cyanide content of 1358 mg / kg to deionized water to make a pulp with a mass concentration of 30%.

[0078] (2) Adjust the pH value of the pulp to 7.5 with sodium hydroxide to make a slurry.

[0079] (3) Pour the pulp obtained in step (2) into a conical flask, add a catalyst and hydrogen peroxide (mass percentage concentration is 20%) in a certain proportion. The addition amount of hydrogen peroxide is 15 g per liter of pulp, and the addition amount of the catalyst is 5.5 g per liter of pulp. Then place the conical flask in a constant temperature magnetic stirring water bath device (temperature controlled at 70 °C, stirring speed is 400 rpm) and adjust the height of the ultraviolet light source (ultraviolet light wavelength 253.7 nm) to make the light in the flask fully and evenly distributed, and the light intensity is 235 μW / cm 2 . During this period, prevent a large amount of bubbles from overflowing due to heat release in the flask, and the reaction time is 120 min.

[0080] (4) Filtration: Filter the reaction materials with a filter press to obtain filter residue and filtrate.

[0081] (5) Detection: Toxicity detection of the filter residue (HJ / 299 - 2007 "Solid Waste Toxicity Leaching Method - Sulfuric Acid and Nitric Acid Method" and HJ484 - 2009 "Determination of Cyanide in Water - Titrimetric Method and Separation Photometric Method") shows that the cyanide concentration is 2 mg / L, which is lower than the national standard (HJ943 - 2018 "Technical Specification for Pollution Control of Cyanide Residue in the Gold Industry"), meeting the discharge standard for direct discharge. That is, the cyanide concentration in the original cyanidation tailings is reduced to 20 mg / kg, and the degradation rate of cyanide in the cyanidation tailings is 98.53%.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements 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 preparing an aluminum-based bimetallic catalyst, characterized in that: The following steps are involved: (1) adding an aluminum-containing compound to an acid solution, soaking and removing impurities, washing with water for 1 to 5 times, and drying to obtain activated alumina; (2) Dissolve the iron salt and zinc salt in distilled water, add the activated alumina obtained in step (1) and mix well, control the molar ratio of aluminum to zinc in the activated alumina to be 1:0.01 to 1:0.4, and the molar ratio of aluminum to iron in the activated alumina to be 1:0.01 to 1:0.30; (3) The mixture obtained in step (2) is stirred at a temperature of 40 to 80° C. and a stirring speed of 100 to 1000 rpm for 6 to 24 hours, and then calcined at 300 to 950° C. for 2 to 10 hours to obtain an aluminum-based bimetallic catalyst precursor; (4) Grinding the aluminum-based bimetallic catalyst precursor obtained in step (3) into powder, and then drying and placing it in a constant temperature drying oven to obtain an aluminum-based bimetallic catalyst.

2. The preparation method according to claim 1, characterized in that: The aluminum-containing compound described in step (1) is selected from aluminum oxide or aluminum hydroxide, preferably γ-Al2O3; the acid solution is concentrated nitric acid, the concentration is 2-10 mol / L, and the soaking time is 3-24 hours; the drying temperature is 105-150°C, the drying time is 12-36 hours, and the pH range after drying is 4.5-6.

5.

3. The preparation method according to claim 1, characterized in that: The iron salt described in step (2) is nitrate, sulfate, chloride, acetate and hydrate of iron, and the zinc salt is nitrate, sulfate, chloride, acetate and hydrate of zinc; the molar ratio of aluminum to zinc in the activated alumina is 1:0.10 to 1:0.3, and the molar ratio of aluminum to iron in the activated alumina is 1:0.03 to 1:0.

25.

4. The preparation method according to claim 1, characterized in that: In step (3), the calcination temperature is 500-950° C. and the calcination time is 2-6 hours.

5. The preparation method according to claim 1, characterized in that: In step (4), the drying temperature is 80-110° C., the drying time is 1-12 h, and the constant temperature drying temperature is 60-80° C., and the drying time is 10-24 h.

6. An aluminum-based bimetallic catalyst prepared by the preparation method according to any one of claims 1 to 5.

7. A method for photo-Fenton degradation of gold cyanide tailings using the aluminum-based bimetallic catalyst according to claim 6, characterized in that: The steps include: 1) adding deionized water to the cyanide tailings to prepare a slurry with a mass concentration of 10 to 40%, and adjusting the pH value to 6.5 to 8.5 to obtain a slurry; 2) adding an aluminum-based bimetallic catalyst and hydrogen peroxide to the slurry obtained in step 1), stirring the mixture for 30 to 180 minutes at a temperature of 30 to 80° C., a stirring speed of 100 to 500 rpm, and ultraviolet light irradiation; 3) The reaction material obtained in step 2) is filtered using a filter press to obtain a filter residue and a filtrate.

8. The method according to claim 7, characterized in that The cyanide content in the cyanidation tailings in step 1) is 1000-1500 mg / kg.

9. The method according to claim 7, characterized in that: In step 2), the amount of catalyst added is 1-10 g / L slurry, the amount of hydrogen peroxide added is 2-30 g / L slurry, and the mass percentage concentration of hydrogen peroxide is 3%-30%; the wavelength of the ultraviolet light source is 250-255 nm, and the light intensity is 10-400 μW / cm 2 .

10. The method according to claim 7, characterized in that The degradation rate of cyanide in cyanide tailings is over 95%.

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