A method for co-utilizing red mud and arsenic soda residue to prepare a composite catalyst, its product and application

Abstract

The present invention discloses a method for co-utilizing red mud and arsenic alkali residue to prepare a composite catalyst, its product and application, belonging to the field of resource utilization of industrial waste. The preparation process of the method of the present invention is simple, the raw materials for preparation are widely sourced, and the full utilization of red mud and arsenic alkali residue can be achieved. Compared with traditional titanium dioxide and iron arsenate catalysts, the composite catalyst prepared by the present invention has more excellent performance, can significantly improve the treatment efficiency of landfill leachate, and can achieve the catalytic removal effect of up to 2145 mg / g COD, 162 mg / g total phosphorus, 356 mg / g ammonia nitrogen, and 122 mg / g mercury.

Description

Technical Field

[0001] The present invention belongs to the field of resource utilization of industrial waste, and particularly relates to a method for co-utilizing red mud and arsenic soda residue to prepare a composite catalyst, its product and application. Background Art

[0002] As typical industrial wastes, red mud and arsenic soda residue have significant research value in terms of environmental hazards and resource potential. As a by-product of alumina production, the strong alkalinity of red mud causes a significant increase in the soil pH value in the stacking area, forming a large area of alkalized land. The alkalinity of the red mud attached solution far exceeds the suitable range of public water sources, posing a continuous pollution threat to surface water and groundwater systems. Arsenic soda residue is a hazardous waste generated during antimony smelting, with an arsenic content often exceeding 10%, and associated heavy metals such as antimony and lead. Traditional solidification and landfill methods are difficult to solve its long-term stability problem, and the leaching of heavy metals under rainwater scouring poses a potential risk to the ecosystem.

[0003] Although red mud and arsenic soda residue are industrial wastes, they contain various metal elements and minerals and have certain potential value. Co-utilizing the two to prepare a composite catalyst can convert these wastes into catalytically active materials, realizing the secondary utilization of resources and improving the resource utilization efficiency. The preparation of traditional catalysts usually requires the consumption of a large amount of natural mineral resources. Using red mud and arsenic soda residue to prepare a composite catalyst can reduce the dependence on these natural resources and is beneficial to protecting natural resources and the ecological environment.

[0004] As industrial wastes, red mud and arsenic soda residue have relatively low acquisition costs. Using them as raw materials to prepare a composite catalyst can significantly reduce the production cost of the catalyst and improve the economic efficiency and competitiveness of the catalyst in industrial applications. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a method for co-utilizing red mud and arsenic soda residue to prepare a composite catalyst, its product and application.

[0006] Technical Solution: The present invention provides a method for co-utilizing red mud and arsenic soda residue to prepare a composite catalyst, including the following steps:

[0007] (1) Mix red mud and arsenic soda residue, and stir evenly to obtain alkaline mud residue;

[0008] (2) Mix sulfuric acid solution and alkaline mud residue, and stir evenly to obtain acid-loaded mud residue;

[0009] (3) Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder;

[0010] (4) Mix lignosulfonate and roasted powder, and stir evenly to obtain roasted sulfonic acid mixed powder;

[0011] (5) Mix the water and the calcined sulfonic acid mixed powder, granulate, and let stand to obtain calcined green pellets; place the calcined raw material in a hydrothermal autoclave to carry out hydrothermal reaction on the calcined green pellets to obtain hydrothermally catalytic raw material; calcine the hydrothermally catalytic raw material to obtain the composite catalyst.

[0012] Further, the mass ratio of the red mud to the arsenic soda residue in step (1) is 30-60:100.

[0013] Further, the liquid-solid ratio of the sulfuric acid solution to the alkali sludge residue in step (2) is 0.25-0.55:1 mL / g; the concentration of the sulfuric acid solution is 2-8 M.

[0014] Further, the calcination temperature in step (3) is 450-850 °C, the calcination time is 0.5-4.5 hours, and the grinding time is 10-30 minutes.

[0015] Further, the mass ratio of the lignosulfonate to the calcined powder in step (4) is 0.5-2.5:100.

[0016] Further, the lignosulfonate in step (4) is any one or a combination of sodium lignosulfonate, calcium lignosulfonate, and potassium lignosulfonate.

[0017] Further, the liquid-solid ratio of the water to the calcined sulfonic acid mixed powder in step (5) is 0.35-0.65:1 mL / g; the standing time is 0.5-2.5 days; the hydrothermal time is 0.5-4.5 hours, the hydrothermal temperature is 120-240 °C; the calcination temperature is 550-950 °C, and the calcination time is 0.5-4.5 hours.

[0018] The present invention also provides the composite catalyst prepared by the above method.

[0019] The present invention also provides the application of the above composite catalyst in sewage treatment.

[0020] Further, the sewage treatment includes removing one or more of COD, phosphorus, ammonia nitrogen, and mercury ions.

[0021] Reaction mechanism: Roast the acid-loaded sludge. Under high-temperature environment, sulfuric acid reacts with arsenic alkali residue and red mud, promoting the release of trivalent arsenic, trivalent antimony and low-valent selenium in the arsenic alkali residue and their conversion to pentavalent arsenate, pentavalent antimonate and selenate, and promoting the release of iron, titanium and calcium in the red mud. At the same time, under the high-temperature roasting environment, the un-released aluminosilicate minerals and calcium and magnesium-containing minerals in the red mud react with sodium carbonate and part of sulfate radicals in the arsenic alkali residue to form a composite mineral mixture. Mix water and roasted sulfonic acid mixed powder. During the standing process, the composite mineral mixture in the roasted sulfonic acid mixed powder undergoes self-excitation to form a gel. Lignosulfonate adsorbs some heavy metal elements through ion exchange and is fully wrapped by the gel. Part of iron, titanium, calcium and some heavy metals (lead, copper, nickel) undergo hydrolysis and react with arsenate, antimonate and selenate to form a mixed precipitate of arsenate, antimonate and selenate. During the hydrothermal process, iron, titanium and heavy metals are further hydrolyzed, and at the same time, the production amount of the mixed precipitate of arsenate, antimonate and selenate further increases, and the gel hydrothermally hardens, realizing the efficient fixation of the mixed precipitate of arsenate, antimonate and selenate and the hydrolysis products of titanium and heavy metals. Roast the hydrothermal catalytic raw material. Under high-temperature environment, the mixed precipitate of arsenate, antimonate and selenate locally fuses, and the hydrolysis products of titanium and heavy metals dehydrate and are mixed and converted into a mixture of metal oxides.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: The preparation process of the present invention is simple, the sources of preparation raw materials are wide, and the full utilization of red mud and arsenic alkali residue can be realized. Compared with the traditional titanium dioxide and iron arsenate catalysts, the composite catalyst prepared by the present invention has more excellent performance, can significantly improve the treatment efficiency of landfill leachate, and can achieve the catalytic removal effect of up to 2145mg / g COD, 162mg / g total phosphorus, 356mg / g ammonia nitrogen, and 122mg / g mercury at most. Description of the drawings

[0023] Figure 1 It is the flow chart of the treatment method of the present invention. Detailed implementation manners

[0024] The technical solutions of the present invention will be further described below in conjunction with the drawings.

[0025] Preparation of landfill leachate and landfill leachate containing mercury: The landfill leachate used in the experiment was taken from Zhuji Sanfeng Environmental Energy Co., Ltd. The COD mass concentration of this batch of landfill leachate was 4152mg / L, the concentration of total phosphorus was 305mg / L, and the concentration of ammonia nitrogen was 1075mg / L. Add 500mg of mercury to 1L of landfill leachate and stir evenly to prepare the landfill leachate containing mercury.

[0026] Red mud: provided by Shandong Zibo Zhengheng Aluminum Co., Ltd., the main detected components include: 38.52% Fe2O3, 27.83% Al2O3, 12.49% SiO2, 11.36% Na2O, 5.61% TiO2, 0.57% CaO, 0.34% SO3 and other components (inevitable impurities and loss on ignition);

[0027] Arsenic alkali residue: provided by Lengshuijiang Antidu Environmental Protection Co., Ltd., the main detected components include: 56.07% Na2CO3, 11.65% NaHCO3, 9.13% Na3AsO4, 4.65% Na3SbO3, 4.54% Na3AsO3, 2.11% NaOH and other components (inevitable impurities and loss on ignition).

[0028] Example 1 Influence of the mass ratio of red mud to arsenic alkali residue on the performance of the prepared catalyst

[0029] Mix red mud and arsenic alkali residue according to the mass ratios of 22.5:100, 25:100, 27.5:100, 30:100, 45:100, 60:100, 65:100, 70:100, 75:100, stir evenly to obtain alkali mud residue. Mix sulfuric acid solution and alkali mud residue according to the liquid-solid ratio of 0.25:1 mL / g, stir evenly to obtain acid-loaded mud residue, where the concentration of the sulfuric acid solution is 2M. Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder, where the roasting temperature is 450 °C, the roasting time is 0.5 hours, and the grinding time is 10 minutes. Mix lignosulfonate and roasted powder according to the mass ratio of 0.5:100, stir evenly to obtain roasted sulfonic acid mixed powder, where the lignosulfonate is sodium lignosulfonate. Mix water and roasted sulfonic acid mixed powder according to the liquid-solid ratio of 0.35:1 mL / g, granulate, and let stand for 0.5 days to obtain roasted green pellets. Place the roasted green pellets in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermally catalytic green pellets, where the hydrothermal time is 0.5 hours and the hydrothermal temperature is 120 °C. Roast the hydrothermally catalytic green pellets to obtain a composite catalyst, where the roasting temperature is 550 °C and the roasting time is 0.5 hours.

[0030] Photocatalytic removal test: Put 1 g of the catalyst into 1 L of landfill leachate, stir at a speed of 120 rmp while irradiating with an ultraviolet lamp for 120 min, and then centrifuge at a speed of 5000 rpm for solid-liquid separation. Detect the concentrations of different pollutants in the separated liquid and calculate the removal rate. The specific detection and calculation are as follows.

[0031] COD concentration detection and calculation of COD removal capacity: The chemical oxygen demand COD concentration of the leachate is determined according to the national standard "Water Quality - Determination of Chemical Oxygen Demand - Dichromate Method" (GB 11914-1989). The COD removal capacity is calculated according to formula (1), where is the COD removal capacity (mg / g), and are the COD concentrations (mg / L) of the domestic waste leachate before and after treatment, m is the mass of the catalyst (1 g), and V is the volume of the waste leachate (1 L).

[0032] (1)

[0033] Total phosphorus concentration detection and total phosphorus removal capacity calculation: The total phosphorus concentration of the leachate is determined according to the standard "Water Quality - Determination of Phosphate and Total Phosphorus - Continuous Flow - Ammonium Molybdate Spectrophotometry" (HJ 670-2013). The total phosphorus removal rate is calculated according to formula (2), where is the total phosphorus removal capacity (mg / g), and are the total phosphorus concentrations (mg / L) of the domestic waste leachate before and after treatment, m is the mass of the catalyst (1 g), and V is the volume of the waste leachate (1 L).

[0034] (2)

[0035] Ammonia nitrogen concentration detection and ammonia nitrogen removal capacity calculation: The concentration of ammonia nitrogen in the leachate is determined according to "Water Quality - Determination of Ammonia Nitrogen - Salicylic Acid Spectrophotometry" (HJ536-2009). The ammonia nitrogen removal capacity is calculated according to formula (3), where is the ammonia nitrogen removal capacity (mg / g), is the initial concentration of ammonia nitrogen in the leachate before treatment (mg / L), is the remaining concentration of ammonia nitrogen in the treated leachate (mg / L).

[0036] (3)

[0037] Mercury ion concentration detection and removal capacity calculation: The mercury ion concentration in the leachate is determined according to "Water Quality - Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony - Atomic Fluorescence Spectrometry" (HJ 694-2014). The mercury ion removal capacity is calculated according to formula (4), where is the mercury ion removal capacity (mg / g), is the initial concentration of mercury ions in the leachate before treatment (mg / L), is the mercury ion concentration in the treated leachate (mg / L), V is the volume of the waste leachate (1 L), m is the mass of the waste liquid purifying agent (1 g).

[0038] (4)

[0039] The test results of this example are shown in Table 1.

[0040] Table 1 Influence of the mass ratio of red mud to arsenic alkali residue on the performance of the prepared catalyst

[0041]

[0042] As can be seen from Table 1, when the mass ratio of red mud to arsenic alkali residue is less than 30:100 (such as in Table 1, when the mass ratio of red mud to arsenic alkali residue = 27.5:100, 25:100, 22.5:100 and lower ratios not listed in Table 1), less red mud is added, and the reaction between red mud and arsenic alkali residue during roasting is insufficient, resulting in a significant decrease in the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the prepared catalyst as the mass ratio of red mud to arsenic alkali residue decreases. When the mass ratio of red mud to arsenic alkali residue is equal to 30 - 60:100 (such as in Table 1, when the mass ratio of red mud to arsenic alkali residue = 30:100, 45:100, 60:100), roasting the acid-loaded mud residue, sulfuric acid reacts with arsenic alkali residue and red mud in a high-temperature environment, promoting the release of trivalent arsenic, trivalent antimony, and low-valent selenium in arsenic alkali residue and their conversion to pentavalent arsenate, pentavalent antimonate, and selenate, and promoting the release of iron, titanium, and calcium in red mud. At the same time, in the high-temperature roasting environment, the un-released aluminosilicate minerals and calcium and magnesium-containing minerals in red mud react with sodium carbonate and part of sulfate radicals in arsenic alkali residue to form a composite mineral mixture. Finally, the prepared catalyst has a COD removal capacity higher than 1782 mg / g, a total phosphorus removal capacity higher than 124 mg / g, an ammonia nitrogen removal capacity higher than 265 mg / g, and a mercury removal capacity higher than 78 mg / g. When the mass ratio of red mud to arsenic alkali residue is greater than 60:100 (such as in Table 1, when the mass ratio of red mud to arsenic alkali residue = 65:100, 70:100, 75:100 and higher ratios not listed in Table 1), excessive red mud is added, and the reaction between red mud and arsenic alkali residue during roasting is unbalanced, resulting in a significant decrease in the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the prepared catalyst as the mass ratio of red mud to arsenic alkali residue further increases. Generally speaking, considering the benefits and costs, when the mass ratio of red mud to arsenic alkali residue is equal to 30 - 60:100, it is most beneficial to improve the performance of the prepared catalyst.

[0043] Example 2 Influence of the liquid-solid ratio of sulfuric acid solution and alkali mud residue on the performance of the prepared catalyst

[0044] Mix red mud and arsenic alkali residue in a mass ratio of 60:100, stir evenly to obtain alkali mud residue. Mix sulfuric acid solution and alkali mud residue in liquid-solid ratios of 0.1:1 mL / g, 0.15:1 mL / g, 0.2:1 mL / g, 0.25:1 mL / g, 0.4:1 mL / g, 0.55:1 mL / g, 0.6:1 mL / g, 0.65:1 mL / g, 0.7:1 mL / g, stir evenly to obtain acid-loaded mud residue, where the concentration of the sulfuric acid solution is 5 M. Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder, where the roasting temperature is 650 °C, the roasting time is 2.5 hours, and the grinding time is 20 minutes. Mix lignosulfonate and roasted powder in a mass ratio of 1.5:100, stir evenly to obtain roasted sulfonic acid mixed powder, where the lignosulfonate is calcium lignosulfonate. Mix water and roasted sulfonic acid mixed powder in a liquid-solid ratio of 0.5:1 mL / g, granulate, and let it stand for 1.5 days to obtain roasted green pellets. Place the roasted green pellets in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermally catalyzed green pellets, where the hydrothermal time is 2.5 hours and the hydrothermal temperature is 180 °C. Roast the hydrothermally catalyzed green pellets to obtain a composite catalyst, where the roasting temperature is 750 °C and the roasting time is 2.5 hours.

[0045] The photocatalytic removal test, the detection of COD concentration and the calculation of COD removal capacity, the detection of total phosphorus concentration and the calculation of total phosphorus removal capacity, the detection of ammonia nitrogen concentration and the calculation of ammonia nitrogen removal capacity, and the detection of mercury ion concentration and the calculation of removal capacity are the same as those in Example 1. The test results of this example are shown in Table 2.

[0046] Table 2 Influence of the liquid-solid ratio of sulfuric acid solution and alkali mud residue on the performance of the prepared catalyst

[0047]

[0048] As can be seen from Table 2, when the solid-liquid ratio of sulfuric acid solution to alkali sludge residue is less than 0.25:1 mL / g (as in Table 2, when the solid-liquid ratio of sulfuric acid solution to alkali sludge residue = 0.2:1 mL / g, 0.15:1 mL / g, 0.1:1 mL / g and lower ratios not listed in Table 2), less sulfuric acid solution is added, and the reaction between the sulfuric acid solution and the alkali sludge residue is insufficient during the roasting process, resulting in a significant decrease in the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the prepared catalyst as the solid-liquid ratio of sulfuric acid solution to alkali sludge residue decreases. When the solid-liquid ratio of sulfuric acid solution to alkali sludge residue is equal to 0.25 - 0.55:1 mL / g (as in Table 2, when the solid-liquid ratio of sulfuric acid solution to alkali sludge residue = 0.25:1 mL / g, 0.4:1 mL / g, 0.55:1 mL / g), roasting the acid-loaded sludge residue, sulfuric acid reacts with arsenic alkali residue and red mud in a high-temperature environment, promoting the release of trivalent arsenic, trivalent antimony, and low-valent selenium in the arsenic alkali residue and their conversion to pentavalent arsenate, pentavalent antimonate, and selenate, and promoting the release of iron, titanium, and calcium in the red mud. At the same time, in the high-temperature roasting environment, the un-released aluminosilicate minerals and calcium and magnesium-containing minerals in the red mud react with sodium carbonate and some sulfate radicals in the arsenic alkali residue to form a composite mineral mixture. Finally, the prepared catalyst has a COD removal capacity higher than 1873 mg / g, a total phosphorus removal capacity higher than 137 mg / g, an ammonia nitrogen removal capacity higher than 291 mg / g, and a mercury removal capacity higher than 89 mg / g. When the solid-liquid ratio of sulfuric acid solution to alkali sludge residue is greater than 0.55:1 mL / g (as in Table 2, when the solid-liquid ratio of sulfuric acid solution to alkali sludge residue = 0.6:1 mL / g, 0.65:1 mL / g, 0.7:1 mL / g and higher ratios not listed in Table 2), excessive sulfuric acid solution is added, and the reaction between the sulfuric acid solution and the alkali sludge residue is unbalanced during the roasting process, resulting in a significant decrease in the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the prepared catalyst as the solid-liquid ratio of sulfuric acid solution to alkali sludge residue further increases. Generally speaking, considering the benefits and costs, when the solid-liquid ratio of sulfuric acid solution to alkali sludge residue is equal to 0.25 - 0.55:1 mL / g, it is most beneficial to improve the performance of the prepared catalyst.

[0049] Example 3 Influence of the mass ratio of lignosulfonate to roasted powder on the performance of the prepared catalyst

[0050] Mix red mud and arsenic alkali residue in a mass ratio of 60:100, stir evenly to obtain alkali mud residue. Mix sulfuric acid solution and alkali mud residue in a liquid-solid ratio of 0.55:1 mL / g, stir evenly to obtain acid-loaded mud residue, where the concentration of the sulfuric acid solution is 8 M. Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder, where the roasting temperature is 850 °C, the roasting time is 4.5 hours, and the grinding time is 30 minutes. Mix lignosulfonate and roasted powder in mass ratios of 0.25:100, 0.3:100, 0.4:100, 0.5:100, 1.5:100, 2.5:100, 2.75:100, 3:100, 3.25:100, stir evenly to obtain roasted sulfonic acid mixed powder, where the lignosulfonate is potassium lignosulfonate. Mix water and roasted sulfonic acid mixed powder in a liquid-solid ratio of 0.65:1 mL / g, granulate, and let stand for 2.5 days to obtain roasted green pellets. Place the roasted green pellets in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermally catalytic green pellets, where the hydrothermal time is 4.5 hours and the hydrothermal temperature is 240 °C. Roast the hydrothermally catalytic green pellets to obtain a composite catalyst, where the roasting temperature is 950 °C and the roasting time is 4.5 hours.

[0051] The photocatalytic removal test, the detection of COD concentration and the calculation of COD removal capacity, the detection of total phosphorus concentration and the calculation of total phosphorus removal capacity, the detection of ammonia nitrogen concentration and the calculation of ammonia nitrogen removal capacity, and the detection of mercury ion concentration and the calculation of removal capacity are the same as in Example 1. The test results of this example are shown in Table 3.

[0052] Table 3 Influence of the mass ratio of lignosulfonate and roasted powder on the performance of the prepared catalyst

[0053]

[0054] As can be seen from Table 3, when the mass ratio of lignosulfonate to calcined powder is less than 0.5:100 (as shown in Table 3, when the mass ratio of lignosulfonate to calcined powder = 0.4:100, 0.3:100, 0.25:100 and lower ratios not listed in Table 3), less lignosulfonate is added, and the reaction between lignosulfonate and calcined powder is insufficient during the hydrothermal reaction, resulting in a significant decrease in the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the prepared catalyst with the decrease in the mass ratio of lignosulfonate to calcined powder. When the mass ratio of lignosulfonate to calcined powder is equal to 0.5 - 2.5:100 (as shown in Table 3, when the mass ratio of lignosulfonate to calcined powder = 0.5:100, 1.5:100, 2.5:100), lignosulfonate adsorbs some heavy metal elements through ion exchange and is fully wrapped by the gel. Some iron, titanium, calcium, and some heavy metals (lead, copper, nickel) undergo hydrolysis and react with arsenate, antimonate, and selenate to form a mixed precipitate of arsenate, antimonate, and selenate. During the hydrothermal process, iron, titanium, and heavy metals further hydrolyze, and at the same time, the amount of the mixed precipitate of arsenate, antimonate, and selenate generated further increases, and the gel hydrothermally hardens, achieving efficient fixation of the mixed precipitate of arsenate, antimonate, and selenate and the hydrolysis products of titanium and heavy metals. The hydrothermal catalytic raw material is calcined, and the mixed precipitate of arsenate, antimonate, and selenate locally fuses under high temperature, and the hydrolysis products of titanium and heavy metals dehydrate and are mixed and transformed into a mixture of metal oxides. Finally, the prepared catalyst has a COD removal capacity higher than 2017 mg / g, a total phosphorus removal capacity higher than 147 mg / g, an ammonia nitrogen removal capacity higher than 318 mg / g, and a mercury removal capacity higher than 108 mg / g. When the mass ratio of lignosulfonate to calcined powder is greater than 2.5:100 (as shown in Table 3, when the mass ratio of lignosulfonate to calcined powder = 2.75:100, 3:100, 3.25:100 and higher ratios not listed in Table 3), excessive lignosulfonate is added, and the reaction between lignosulfonate and calcined powder is unbalanced during the hydrothermal reaction, resulting in a significant decrease in the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the prepared catalyst with the further increase in the mass ratio of lignosulfonate to calcined powder. Generally speaking, considering the benefits and costs, when the mass ratio of lignosulfonate to calcined powder is equal to 0.5 - 2.5:100, it is most beneficial to improve the performance of the prepared catalyst.

[0055] Comparative Example 1 Influence of Different Preparation Processes on the Performance of the Prepared Catalyst

[0056] Process of the present invention: Mix red mud and arsenic alkali residue in a mass ratio of 60:100, stir evenly to obtain alkali mud residue. Mix sulfuric acid solution and alkali mud residue in a liquid-solid ratio of 0.55:1 mL / g, stir evenly to obtain acid-loaded mud residue, where the concentration of the sulfuric acid solution is 5M. Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder, where the roasting temperature is 650°C, the roasting time is 4.5 hours, and the grinding time is 30 minutes. Mix lignosulfonate and roasted powder in a mass ratio of 2.5:100, stir evenly to obtain roasted sulfonic acid mixed powder, where the lignosulfonate is potassium lignosulfonate. Mix water and roasted sulfonic acid mixed powder in a liquid-solid ratio of 0.65:1 mL / g, granulate, and let stand for 2.5 days to obtain roasted green pellets. Place the roasted raw material in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermally catalyzed raw material, where the hydrothermal time is 4.5 hours and the hydrothermal temperature is 240°C. Roast the hydrothermally catalyzed raw material to obtain a composite catalyst, where the roasting temperature is 950°C and the roasting time is 4.5 hours.

[0057] Comparative process 1: Mix red mud and arsenic alkali residue in a mass ratio of 60:100, stir evenly to obtain alkali mud residue. Mix sulfuric acid solution and alkali mud residue in a liquid-solid ratio of 0.55:1 mL / g, stir evenly to obtain acid-loaded mud residue, where the concentration of the sulfuric acid solution is 5M. Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder, where the roasting temperature is 650°C, the roasting time is 4.5 hours, and the grinding time is 30 minutes. Mix water and roasted powder in a liquid-solid ratio of 0.65:1 mL / g, granulate, and let stand for 2.5 days to obtain roasted green pellets. Place the roasted raw material in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermally catalyzed raw material, where the hydrothermal time is 4.5 hours and the hydrothermal temperature is 240°C. Roast the hydrothermally catalyzed raw material to obtain a composite catalyst, where the roasting temperature is 950°C and the roasting time is 4.5 hours.

[0058] Comparative process 2: Mix sulfuric acid solution and red mud in a liquid-solid ratio of 0.55:1 mL / g, stir evenly to obtain acid-loaded mud, where the concentration of the sulfuric acid solution is 5M. Roast the acid-loaded mud, and then grind the roasted residue to obtain roasted powder, where the roasting temperature is 650°C, the roasting time is 4.5 hours, and the grinding time is 30 minutes. Mix lignosulfonate and roasted powder in a mass ratio of 2.5:100, stir evenly to obtain roasted sulfonic acid mixed powder, where the lignosulfonate is potassium lignosulfonate. Mix water and roasted sulfonic acid mixed powder in a liquid-solid ratio of 0.65:1 mL / g, granulate, and let stand for 2.5 days to obtain roasted green pellets. Place the roasted raw material in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermally catalyzed raw material, where the hydrothermal time is 4.5 hours and the hydrothermal temperature is 240°C. Roast the hydrothermally catalyzed raw material to obtain a composite catalyst, where the roasting temperature is 950°C and the roasting time is 4.5 hours.

[0059] The photocatalytic removal test, the detection of COD concentration and the calculation of COD removal capacity, the detection of total phosphorus concentration and the calculation of total phosphorus removal capacity, the detection of ammonia nitrogen concentration and the calculation of ammonia nitrogen removal capacity, and the detection of mercury ion concentration and the calculation of removal capacity are the same as those in Example 1. The test results of this comparative example are shown in Table 4.

[0060] Table 4 Influence of different preparation processes on the performance of the prepared catalysts

[0061]

[0062] As can be seen from Table 4, the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the catalysts prepared by the process of the present invention are significantly higher than those of the catalysts prepared by Comparative Process 1 and Comparative Process 2.

[0063] Comparative Example 2 Comparison of the performance of different catalysts

[0064] Process of the present invention: Mix red mud and arsenic alkali residue in a mass ratio of 60:100, stir evenly to obtain alkali mud residue. Mix sulfuric acid solution and alkali mud residue in a liquid-solid ratio of 0.55:1 mL / g, stir evenly to obtain acid-loaded mud residue, where the concentration of the sulfuric acid solution is 5M. Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder, where the roasting temperature is 650 °C, the roasting time is 4.5 hours, and the grinding time is 30 minutes. Mix lignosulfonate and roasted powder in a mass ratio of 2.5:100, stir evenly to obtain roasted sulfonic acid mixed powder, where the lignosulfonate is potassium lignosulfonate. Mix water and roasted sulfonic acid mixed powder in a liquid-solid ratio of 0.65:1 mL / g, granulate, and let stand for 2.5 days to obtain roasted green pellets. Place the roasted green pellets in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermally catalytic green pellets, where the hydrothermal time is 0.5 hours and the hydrothermal temperature is 240 °C. Roast the hydrothermally catalytic green pellets to obtain a composite catalyst, where the roasting temperature is 550 °C and the roasting time is 4.5 hours.

[0065] The photocatalytic removal test, the detection of COD concentration and the calculation of COD removal capacity, the detection of total phosphorus concentration and the calculation of total phosphorus removal capacity, the detection of ammonia nitrogen concentration and the calculation of ammonia nitrogen removal capacity, and the detection of mercury ion concentration and the calculation of removal capacity are the same as those in Example 1. The test results of this comparative example are shown in Table 5.

[0066] Table 5 Comparison of the performance of different catalysts

[0067]

[0068] As can be seen from Table 5, the COD, total phosphorus, ammonia nitrogen, and mercury removal capacities of the catalysts prepared by the process of the present invention are significantly higher than those of titanium dioxide and iron arsenate catalysts.

Claims

1. A method for co - utilizing red mud and arsenic - containing soda residue to prepare a composite catalyst, characterized in that, It includes the following steps: (1) Mix red mud and arsenic alkali residue, and stir evenly to obtain alkali mud residue; The mass ratio of the red mud to the arsenic alkali residue is 30 - 60:100; (2) Mix sulfuric acid solution and alkali mud residue, and stir evenly to obtain acid-loaded mud residue; (3) Roast the acid-loaded mud residue, and then grind the roasted residue to obtain roasted powder; (4) Mix lignosulfonate and roasted powder, and stir evenly to obtain roasted sulfonic acid mixed powder; (5) Mix water and roasted sulfonic acid mixed powder, granulate, and stand still to obtain roasted green pellets; Place the roasted raw material in a hydrothermal autoclave to carry out hydrothermal reaction on the roasted green pellets to obtain hydrothermal catalytic raw material; Roast the hydrothermal catalytic raw material to obtain the composite catalyst.

2. The method for co-utilizing red mud and arsenic alkali residue to prepare a composite catalyst according to claim 1, characterized in that, In step (2), the liquid-solid ratio of the sulfuric acid solution to the alkali mud residue is 0.25 - 0.55:1 mL / g; The concentration of the sulfuric acid solution is 2 - 8 M.

3. The method for co-using red mud and arsenic alkali residue to prepare a composite catalyst according to claim 1, wherein In step (3), the roasting temperature is 450 - 850 °C, the roasting time is 0.5 - 4.5 hours, and the grinding time is 10 - 30 minutes.

4. The method for co-using red mud and arsenic alkali residue to prepare a composite catalyst according to claim 1, wherein In step (4), the mass ratio of the lignosulfonate to the roasted powder is 0.5 - 2.5:

100.

5. The method for co-using red mud and arsenic alkali residue to prepare a composite catalyst according to claim 1, characterized in that, In step (4), the lignosulfonate is any one or a combination of sodium lignosulfonate, calcium lignosulfonate, and potassium lignosulfonate.

6. The method for co-using red mud and arsenic alkali residue to prepare a composite catalyst according to claim 1, wherein, In step (5), the liquid-solid ratio of water to the roasted sulfonic acid mixed powder is 0.35 - 0.65:1 mL / g; The standing time is 0.5 - 2.5 days; The hydrothermal time is 0.5 - 4.5 hours, and the hydrothermal temperature is 120 - 240 °C; The roasting temperature is 550 - 950 °C, and the roasting time is 0.5 - 4.5 hours.

7. The composite catalyst prepared by the method of any one of claims 1 - 6.

8. Use of the composite catalyst according to claim 7 in sewage treatment, characterized in that, The sewage treatment includes removing one or more of COD, phosphorus, ammonia nitrogen, and mercury ions.

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