Manganese lanthanum cerium thorium catalytic composite water purifying agent based on pyrite tailings, preparation method and application thereof

Abstract

This invention provides a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings, its preparation method, and its application. It belongs to the field of solid waste resource utilization technology. The method includes: first, crushing and screening pyrite tailings to obtain tailings powder; then, leaching the powder with sulfuric acid; filtering to obtain an acid leaching solution containing iron and aluminum ions; detecting the iron and aluminum content in the acid leaching solution and adjusting the iron-aluminum ratio; using manganese, lanthanum, cerium, and thorium elements contained in the acid leaching solution as built-in catalysts; then, subjecting the prepared acid leaching solution to an oxidative hydrolysis polymerization reaction to obtain polyferric sulfate or polyaluminum ferric sulfate solution; finally, concentrating and drying the polymerization solution to obtain the composite water purification agent. This invention utilizes the endogenous catalytic synergistic effect of manganese, lanthanum, cerium, and thorium in pyrite tailings, eliminating the need for additional exogenous catalysts, achieving full-component resource utilization of pyrite tailings and significantly improving the performance of the water purification agent.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings, its preparation method, and its application. Background Technology

[0002] Pyrite tailings are solid waste generated during the mining and beneficiation of pyrite. These wastes have high sulfur and iron content, with silicon dioxide as the main gangue mineral, and also contain calcium oxide, aluminum oxide, and other components. Currently, the scale of pyrite tailings stockpiles is enormous, with a total iron content ranging from 21.36% to 38.36%, indicating significant potential for resource utilization. However, current methods for utilizing pyrite tailings are very limited. Large quantities of tailings can only be stockpiled for extended periods, occupying significant amounts of land, potentially causing groundwater pollution, and negatively impacting the surrounding environment. How to efficiently utilize these tailings remains a challenge for the industry.

[0003] Polyferric sulfate and polyaluminum ferric sulfate are commonly used inorganic polymeric flocculants in water treatment, known for their good coagulation effect and wide applicable pH range, making them widely used in the water treatment industry. Currently, numerous technologies are attempting to prepare these water purification agents using pyrite tailings or slag; however, several problems remain in actual production. Specifically, the preparation of polyferric sulfate typically requires the addition of catalysts such as sodium nitrite, nitric acid, and manganese dioxide. These exogenous catalysts not only increase raw material costs but also complicate the production process. Simultaneously, the catalytic properties of trace elements such as manganese, lanthanum, cerium, and thorium naturally present in pyrite tailings have not been effectively utilized. Even studies that optimize water purification agent performance by adding rare earth elements have failed to leverage the inherent composition of the tailings for resource utilization, resulting in the waste of strategic resources such as rare earths and thorium in the tailings and hindering the high-value utilization of all components of the tailings.

[0004] Furthermore, current preparation technologies are unable to efficiently extract the main iron and aluminum components from pyrite tailings, nor can they leverage the endogenous catalytic effects of manganese, lanthanum, cerium, and thorium in the tailings, making it difficult to balance the resource utilization of tailings with the performance and cost control of water purification agents.

[0005] Therefore, it is necessary to provide a composite water purification agent and its preparation method that uses pyrite tailings as raw material and makes full use of the synergistic catalytic effect of manganese, lanthanum, cerium and thorium in the tailings, in order to solve the above-mentioned problems. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings, its preparation method, and its application. By utilizing the endogenous catalytic synergistic effect of manganese, lanthanum, cerium, and thorium in pyrite tailings, the invention achieves the resource utilization of all components of the tailings without the need for additional external catalysts. This significantly improves the polymerization degree and water purification performance of the water purification agent, while also significantly enhancing the removal efficiency of turbidity, COD, total phosphorus, and heavy metals.

[0007] To achieve the above objectives, the present invention provides the following solution: On the one hand, the present invention provides a method for preparing a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings, comprising the following steps: S1. Pyrite tailings are crushed and screened to obtain tailings powder; S2. Add the tailings powder to a sulfuric acid solution with a mass concentration of 20%~60%, mix at a sulfuric acid solution to tailings powder liquid-solid ratio of 3~8:1mL / g, stir and react at 60~130℃ for 1~5h, and filter to obtain Fe-containing... 3+ Al 3+ Acid leaching solution; S3. Detect the iron and aluminum content in the acid leaching solution, and adjust the iron-aluminum molar ratio of the acid leaching solution to 0.5~5:1 based on the detection results; and the manganese, lanthanum, cerium and thorium elements contained in the acid leaching solution serve as built-in catalysts for the oxidative hydrolysis polymerization reaction; S4. Heat the adjusted acid leaching solution to 50~80℃ and carry out an oxidative hydrolysis polymerization reaction for 1~4 hours under stirring to obtain polyferric sulfate or polyaluminum ferric sulfate solution. S5. The polyferric sulfate or polyaluminum ferric sulfate solution is successively concentrated and dried to obtain a composite water purification agent.

[0008] Preferably, in S1, the Fe content in the pyrite tailings is 20%~40%, the Al content is 3%~10%, the Mn content is 0.1%~0.5%, and the total content of La, Ce, and Th is 50~200ppm; the particle size of the tailings powder is not greater than 200 mesh.

[0009] Preferably, in step S1, after obtaining the tailings powder, the method further includes: separating the tailings powder into pyrite concentrate by magnetic separation or shaking table gravity separation, and using the remaining tailings powder for acid leaching reaction.

[0010] Preferably, in S2, the mass concentration of the sulfuric acid solution is 30%~50%, the liquid-to-solid ratio is 4~6:1mL / g, the acid leaching reaction temperature is 80~110℃, and the reaction time is 2~4h.

[0011] Preferably, in S3, the iron-aluminum molar ratio is adjusted to 1~3:1 by adding ferrous sulfate or aluminum sulfate.

[0012] Preferably, in S4, the oxidative hydrolysis polymerization reaction is carried out by introducing air, oxygen or adding an oxidant, wherein the oxidant is selected from one or more of sodium chlorate and hydrogen peroxide, and the amount of oxidant added is 0.5% to 8% of the mass of the acid leaching solution.

[0013] Preferably, in S4, the oxidative hydrolysis polymerization reaction temperature is 60~70℃ and the reaction time is 2~3h.

[0014] Preferably, in step S5, the drying is spray drying or vacuum drying, the drying temperature is 80~120℃, and the product moisture content is ≤5%.

[0015] On the other hand, the present invention also provides a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings prepared according to the above preparation method, wherein the water purification agent uses ferric sulfate / aluminum sulfate as the effective component and contains manganese, lanthanum, cerium and thorium catalytic active components.

[0016] In addition, the aforementioned manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings can be used in water treatment. Specifically, the composite water purification agent is added to the water body to be treated at a dosage of 10~200 mg / L, stirred and mixed, and then allowed to settle for water treatment.

[0017] Compared with the prior art, the present invention discloses at least the following technical effects: (1) This invention uses pyrite tailings as raw material to prepare a composite water purification agent, fully explores the utilization value of iron and aluminum major elements in the tailings, and uses manganese, lanthanum, cerium and thorium trace elements associated with the tailings as built-in catalytic components, without the need to add external catalysts such as sodium nitrite, nitric acid and manganese dioxide, thus reducing the production cost of the water purification agent from the source; at the same time, this method realizes the resource utilization of all components of pyrite tailings, which not only solves the industry problem of tailings piling up occupying land and polluting the ecological environment, but also incorporates rare earth and thorium elements in the tailings that have reached the boundary grade into the catalytic system, realizes the high-value utilization of strategic resources, and thus achieves the environmental protection goal of treating waste with waste.

[0018] (2) This invention is based on the quaternary catalytic effect of manganese, lanthanum, cerium and thorium, which can efficiently promote Fe during the preparation process. 2+ Oxidation, hydrolysis, and polymerization reactions occur, in which manganese ions can activate oxygen, while lanthanum and cerium ions accelerate Fe... 2+ / Fe 3+The redox cycle and thorium ions enhance the charge density and flocculation performance of the polymer products, shortening the oxidative polymerization reaction time by 30% to 50% and increasing the degree of polymerization of the products by more than 20%. At the same time, the preparation process is simple and efficient, without the need for complex extraction and separation equipment and procedures. Iron, aluminum and catalytic elements can be extracted simultaneously through a one-step acid leaching, realizing the integration of "extraction-blending-catalysis-polymerization", which is more suitable for large-scale industrial production.

[0019] (3) The composite water purification agent prepared by the present invention has the advantages of both polyferric sulfate and polyaluminum sulfate. The trace amounts of manganese, lanthanum, cerium and thorium residues give the product stronger charge neutralization and adsorption bridging capabilities. Compared with traditional water purification agents, under the condition of reducing the dosage by 20% to 30%, it can still achieve a turbidity removal rate increase of 5% to 10%, a COD removal rate increase of 10% to 15%, and a total phosphorus removal rate of over 95%. At the same time, it also has excellent synergistic removal effects on iron, manganese heavy metal ions and fluoride ions. The water purification performance is significantly better than that of conventional commercially available water purification products. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating the preparation method of a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings according to the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, this invention provides a method for preparing a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings, comprising the following steps: S1. The pyrite tailings are crushed and screened to obtain tailings powder.

[0025] Specifically, the Fe content in pyrite tailings is 20%–40%, the Al content is 3%–10%, the Mn content is 0.1%–0.5%, and the total content of La, Ce, and Th is 50–200 ppm. After crushing and screening the tailings, controlling the particle size of the tailings powder to be no larger than 200 mesh increases the contact area between the tailings powder and the acid solution, improving the efficiency of the acid leaching reaction. Furthermore, this step can also separate the tailings powder into pyrite concentrate through magnetic separation or shaking table gravity separation, allowing the remaining tailings powder to be used in subsequent reactions, further improving the utilization rate of the tailings raw material.

[0026] S2. Add the tailings powder to a sulfuric acid solution with a mass concentration of 20%~60%, mix at a sulfuric acid solution to tailings powder liquid-solid ratio of 3~8:1mL / g, stir and react at 60~130℃ for 1~5h, and filter to obtain Fe-containing... 3+ Al 3+ The acid leaching solution.

[0027] Specifically, the preferred concentration of the sulfuric acid solution in this step is 30%~50%, the liquid-to-solid ratio is 4~6:1mL / g, the acid leaching reaction temperature is 80~110℃, and the reaction time is 2~4h. The sulfuric acid solution can react with the iron and aluminum minerals in the tailings powder, converting the iron and aluminum components into ionic states and leaching them into the solution. At the same time, manganese, lanthanum, cerium, and thorium in the tailings are leached out simultaneously, providing built-in catalytic components for subsequent reactions. After filtration, insoluble acid leaching residue can be removed to obtain a pure acid leaching solution.

[0028] S3. Detect the iron and aluminum content in the acid leaching solution, and adjust the iron-aluminum molar ratio of the acid leaching solution to 0.5~5:1 based on the detection results; and the manganese, lanthanum, cerium and thorium elements contained in the acid leaching solution serve as built-in catalysts for the oxidative hydrolysis polymerization reaction.

[0029] Specifically, this step preferably adjusts the Fe / Al molar ratio to 1-3:1 by adding ferrous sulfate or aluminum sulfate, based on the required Fe / Al ratio in the target water purifier. Controlling the Fe / Al ratio optimizes the coagulation performance of the final water purifier. The manganese, lanthanum, cerium, and thorium elements naturally present in the acid leaching solution have synergistic catalytic activity, eliminating the need for additional external catalysts. This reduces production costs and provides a catalytic core for the oxidative hydrolysis polymerization reaction, accelerating the reaction process.

[0030] S4. Heat the adjusted acid leaching solution to 50~80℃ and carry out an oxidative hydrolysis polymerization reaction for 1~4 hours under stirring to obtain polyferric sulfate or polyaluminum ferric sulfate solution.

[0031] Specifically, the preferred oxidation-hydrolysis polymerization reaction temperature for this step is 60-70℃, and the reaction time is 2-3 hours. During the reaction, air, oxygen, or one or more oxidants such as sodium chlorate or hydrogen peroxide can be introduced, with the amount of oxidant added being 0.5%-8% of the mass of the acid leaching solution. Under the synergistic catalytic action of manganese, lanthanum, cerium, and thorium, Fe can be rapidly oxidized. 2+ Oxidized to Fe 3+ It also triggers a hydrolysis-polymerization reaction, effectively shortening the reaction time and increasing the degree of polymerization of the product, thereby obtaining a highly active polyferric sulfate or polyaluminum ferric sulfate solution.

[0032] S5. The polyferric sulfate or polyaluminum ferric sulfate solution is successively concentrated and dried to obtain a composite water purification agent.

[0033] Specifically, this step preferably uses spray drying or vacuum drying, controlling the drying temperature at 80~120℃, and drying until the moisture content of the finished product is ≤5%. Concentration can increase the solid content of the polymerization liquid, and drying can remove free water from the product, making it easier to store, transport and add to use, ultimately obtaining a high-efficiency composite water purification agent with ferric sulfate / aluminum sulfate as the effective components and containing manganese, lanthanum, cerium and thorium catalytic active components.

[0034] In addition, the composite water purifier prepared above can be used in water treatment. Specifically, the water purifier is added to the water body to be treated at a dosage of 10~200mg / L, stirred and mixed, and then allowed to settle. This can achieve efficient removal of turbidity, COD, phosphorus and heavy metals.

[0035] The following detailed implementation methods further illustrate the above content. In both the examples and comparative examples, secondary sedimentation effluent from a municipal wastewater treatment plant was used as the test water sample. The initial water quality indicators of this sample were: turbidity 18 NTU, chemical oxygen demand (COD) 52 mg / L, and total phosphorus content 1.8 mg / L. The water purification performance test conditions for all samples were uniformly set as follows: water purification agent dosage 60 mg / L, rapid stirring for 2 minutes, slow stirring for 10 minutes, and settling for 30 minutes before testing the water quality indicators.

[0036] Example 1 Step 1: Select pyrite tailings as raw material. The pyrite tailings contain 32.5% total iron (TFe), 6.8% aluminum oxide (Al2O3), 0.28% manganese (Mn), 45 ppm lanthanum (La), 38 ppm cerium (Ce), and 22 ppm thorium (Th). The pyrite tailings are then crushed, ball-milled, and screened sequentially to control the particle size of the resulting tailings powder to be no larger than 200 mesh, thus obtaining tailings powder that meets the requirements.

[0037] Step 2: Weigh 100g of the above tailings powder and add 500mL of a 40% sulfuric acid solution. The liquid-to-solid ratio of the sulfuric acid solution to the tailings powder is 5:1mL / g. Place the mixture at 95℃ and stir continuously for 3 hours. After the reaction is complete, filter to separate the acid leaching solution and acid leaching residue. The acid leaching solution contains Fe. 3+ Approximately 65g / L, Al 3+ Approximately 12g / L, Mn 2+ Approximately 0.5 g / L, La 3+ +Ce 3+ +Th 4+ Approximately 0.015 g / L.

[0038] Step 3: Detect the iron and aluminum content in the above-mentioned acid leaching solution. The iron-aluminum molar ratio in the acid leaching solution is found to be 5.0:1. Based on the iron-aluminum ratio requirements of the target water purification agent, aluminum sulfate is added to the acid leaching solution to adjust the iron-aluminum molar ratio to 2.5:1. The trace elements manganese, lanthanum, cerium, and thorium contained in this acid leaching solution serve as built-in catalysts for the oxidative hydrolysis polymerization reaction, eliminating the need for additional external catalysts.

[0039] Step 4: Heat the acid leaching solution after adjusting the iron-aluminum molar ratio to 65°C. Under continuous stirring, add sodium chlorate oxidant at a mass of 1.5% of the total mass of the acid leaching solution and introduce air to carry out the oxidative hydrolysis polymerization reaction for 2.5 hours. After the reaction is completed, a polyaluminum ferric sulfate solution is obtained.

[0040] Step 5: The above polyaluminum ferric sulfate solution is vacuum concentrated at 100°C until the solid content of the system is about 40%. Then, it is dried by spray drying at 100°C until the moisture content of the finished product is no more than 5%, thus obtaining a manganese lanthanum cerium thorium catalytic composite water purification agent based on pyrite tailings.

[0041] The composite water purifier prepared in this embodiment underwent water treatment performance testing. After treatment, the effluent turbidity was 1.2 NTU, with a removal rate of 93.3%; COD was 12.5 mg / L, with a removal rate of 76.0%; and total phosphorus was 0.08 mg / L, with a removal rate of 95.6%. In a comparative experiment, commercially available polyferric sulfate (PFS), at the same dosage, treated the same water sample, resulting in an effluent turbidity of 2.5 NTU, a removal rate of 86.1%; COD of 18.6 mg / L, with a removal rate of 64.2%; and total phosphorus of 0.21 mg / L, with a removal rate of 88.3%.

[0042] Example 2 Step 1: Select pyrite tailings as raw material. The pyrite tailings contain 32.5% total iron (TFe), 6.8% aluminum oxide (Al2O3), 0.28% manganese (Mn), 45 ppm lanthanum (La), 38 ppm cerium (Ce), and 22 ppm thorium (Th). The pyrite tailings are then crushed, ball-milled, and screened sequentially to control the particle size of the resulting tailings powder to be no larger than 200 mesh, thus obtaining tailings powder that meets the requirements.

[0043] Step 2: Weigh 100g of the above tailings powder and add 400mL of a 50% sulfuric acid solution. The liquid-to-solid ratio of the sulfuric acid solution to the tailings powder is 4:1mL / g. Place the mixture at 105℃ and stir continuously for 2.5 hours. After the reaction is complete, filter to separate the Fe-containing material. 3+ Al 3+ The acid leaching solution and the acid leaching residue.

[0044] Step 3: Detect the iron and aluminum content in the above-mentioned acid leaching solution. The iron-aluminum molar ratio in the acid leaching solution is 2.8:1. According to the iron-aluminum ratio requirement of the target water purification agent, aluminum sulfate is added to the acid leaching solution to adjust the iron-aluminum molar ratio to 1.5:1. The trace elements manganese, lanthanum, cerium, and thorium contained in this acid leaching solution serve as built-in catalysts for the oxidative hydrolysis polymerization reaction, and no additional external catalyst is required.

[0045] Step 4: Heat the acid leaching solution after adjusting the iron-aluminum molar ratio to 70°C. Under continuous stirring, add hydrogen peroxide oxidant at a mass of 2.0% of the total mass of the acid leaching solution and introduce oxygen to carry out the oxidative hydrolysis polymerization reaction for 2 hours. After the reaction is completed, a polyaluminum ferric sulfate solution is obtained.

[0046] Step 5: The above polyaluminum ferric sulfate solution is vacuum concentrated at 100°C until the solid content of the system is about 40%. Then, it is dried by spray drying at 100°C until the moisture content of the finished product is no more than 5%, thus obtaining a manganese lanthanum cerium thorium catalytic composite water purification agent based on pyrite tailings.

[0047] The composite water purifier prepared in this embodiment was tested for water treatment performance under the same test conditions, and the turbidity removal rate was 91.8%, the COD removal rate was 73.5%, and the total phosphorus removal rate was 94.2%.

[0048] Example 3 Step 1: Select pyrite tailings as raw material. The pyrite tailings contain 32.5% total iron (TFe), 6.8% aluminum oxide (Al2O3), 0.28% manganese (Mn), 45 ppm lanthanum (La), 38 ppm cerium (Ce), and 22 ppm thorium (Th). The pyrite tailings are then crushed, ball-milled, and screened sequentially to control the particle size of the resulting tailings powder to be no larger than 200 mesh, thus obtaining tailings powder that meets the requirements.

[0049] Step 2: Weigh 100g of the above tailings powder and add 600mL of a 30% sulfuric acid solution. The liquid-to-solid ratio of the sulfuric acid solution to the tailings powder is 6:1mL / g. Place the mixture at 85℃ and stir continuously for 4 hours. After the reaction is complete, filter to separate the Fe-containing material. 3+ Al 3+ The acid leaching solution and the acid leaching residue.

[0050] Step 3: Detect the iron and aluminum content in the above-mentioned acid leaching solution. The iron-aluminum molar ratio in the acid leaching solution is found to be 3.5:1. Based on the iron-aluminum ratio requirements of the target water purification agent, aluminum sulfate is added to the acid leaching solution to adjust the iron-aluminum molar ratio to 3.0:1. The trace elements manganese, lanthanum, cerium, and thorium contained in this acid leaching solution serve as built-in catalysts for the oxidative hydrolysis polymerization reaction, eliminating the need for additional external catalysts.

[0051] Step 4: Heat the acid leaching solution after adjusting the iron-aluminum molar ratio to 60°C. Under continuous stirring, add sodium chlorate oxidant at a mass of 1.0% of the total mass of the acid leaching solution and introduce air to carry out the oxidative hydrolysis polymerization reaction for 3 hours. After the reaction is completed, a polyaluminum ferric sulfate solution is obtained.

[0052] Step 5: The above polyaluminum ferric sulfate solution is vacuum concentrated at 100°C until the solid content of the system is about 40%. Then, it is dried by spray drying at 100°C until the moisture content of the finished product is no more than 5%, thus obtaining a manganese lanthanum cerium thorium catalytic composite water purification agent based on pyrite tailings.

[0053] The composite water purifier prepared in this embodiment was tested for water treatment performance under the same test conditions, and the turbidity removal rate was 92.5%, the COD removal rate was 74.8%, and the total phosphorus removal rate was 94.8%.

[0054] Comparative Example 1 This comparative example uses chemically pure reagents as raw materials to prepare polyaluminum ferric sulfate, without using pyrite tailings or adding any catalyst. The specific preparation steps are as follows: Step 1: Select chemically pure ferrous sulfate and chemically pure aluminum sulfate (free of Mn, La, Ce, and Th) as raw materials and mix them according to an iron-aluminum molar ratio of 2.5:1 to obtain a mixed raw material.

[0055] Step 2: Dissolve the above mixed raw materials in water to prepare a mixed solution with the same iron and aluminum concentration as the acid leaching solution in Example 1.

[0056] Step 3: Add sodium chlorate oxidant at a mass of 1.5% of the total mass of the solution to the above mixed solution. Do not add any built-in or external catalyst. Heat the mixed solution to 65°C and carry out the oxidative hydrolysis polymerization reaction under continuous stirring. The reaction needs to be carried out for more than 5.5 hours to achieve a degree of polymerization similar to that in Example 1.

[0057] Step 4: The above polyaluminum ferric sulfate solution is vacuum concentrated at 100°C until the solid content of the system is about 40%. Then, it is dried by spray drying at 100°C until the moisture content of the finished product is no more than 5%, thus obtaining the polyaluminum ferric sulfate sample.

[0058] The water purification agent prepared in this comparative example was tested for water treatment performance under the same test conditions, with a turbidity removal rate of 78.5%, a COD removal rate of 52.3%, and a total phosphorus removal rate of 76.8%.

[0059] Comparative Example 2 This comparative example pre-removes manganese, lanthanum, cerium, and thorium from the acid leaching solution of pyrite tailings, and does not have an internal catalytic system. All other preparation steps and parameters are consistent with Example 1. The specific preparation steps are as follows: Step 1: Select the same pyrite tailings as in Example 1, and process them by crushing, ball milling, and screening to obtain tailings powder with a particle size of no more than 200 mesh.

[0060] Step 2: Weigh 100g of the above tailings powder and add 500mL of 40% sulfuric acid solution to it. The liquid-solid ratio of sulfuric acid solution to tailings powder is 5:1mL / g. Place the mixed solution at 95℃ and stir continuously for 3 hours. Filter to obtain acid leaching solution. Use chemical precipitation to remove trace elements such as manganese, lanthanum, cerium and thorium from the acid leaching solution to obtain acid leaching solution without built-in catalyst.

[0061] Step 3: Detect the iron and aluminum content of the acid leaching solution after impurity removal. The iron-aluminum molar ratio is 3.2:1. Add aluminum sulfate to the acid leaching solution to adjust the iron-aluminum molar ratio to 2.5:1. There is no built-in catalyst in the system, nor is any external catalyst added.

[0062] Step 4: Heat the acid leaching solution after adjusting the iron-aluminum molar ratio to 65°C. Under continuous stirring, add sodium chlorate oxidant at a mass of 1.5% of the total mass of the acid leaching solution and introduce air to carry out the oxidative hydrolysis polymerization reaction for 4.5 hours to obtain polyaluminum ferric sulfate solution.

[0063] Step 5: The above polyaluminum ferric sulfate solution is vacuum concentrated at 100°C until the solid content of the system is about 40%. Then, it is dried by spray drying at 100°C until the moisture content of the finished product is no more than 5%, thus obtaining the polyaluminum ferric sulfate sample.

[0064] The water purification agent prepared in this comparative example was tested for water treatment performance under the same test conditions, with a turbidity removal rate of 82.6%, a COD removal rate of 58.7%, and a total phosphorus removal rate of 80.3%.

[0065] Comparative Example 3 This comparative example does not adjust the iron-aluminum molar ratio of the pyrite tailings acid leaching solution. All other preparation steps and parameters are consistent with those in Example 1. The specific preparation steps are as follows: Step 1: Select the same pyrite tailings as in Example 1, and process them by crushing, ball milling, and screening to obtain tailings powder with a particle size of no more than 200 mesh.

[0066] Step 2: Weigh 100g of the above tailings powder and add 500mL of 40% sulfuric acid solution to it. The liquid-solid ratio of the sulfuric acid solution to the tailings powder is 5:1mL / g. Place the mixed solution at 95℃ and stir continuously for 3 hours. Filter to obtain an acid leaching solution containing manganese, lanthanum, cerium and thorium.

[0067] Step 3: Detect the iron and aluminum content of the acid leaching solution. The iron-aluminum molar ratio is 3.2:1. No ferrous sulfate or aluminum sulfate is added to adjust the iron-aluminum ratio. Manganese, lanthanum, cerium, and thorium in the acid leaching solution are used directly as built-in catalysts.

[0068] Step 4: Heat the acid leaching solution to 65°C, add sodium chlorate oxidant at a mass of 1.5% of the total mass of the acid leaching solution while stirring continuously, and introduce air to carry out the oxidative hydrolysis polymerization reaction for 2.5 hours to obtain polyaluminum ferric sulfate solution.

[0069] Step 5: The above polyaluminum ferric sulfate solution is vacuum concentrated at 100°C until the solid content of the system is about 40%. Then, it is dried by spray drying at 100°C until the moisture content of the finished product is no more than 5%, thus obtaining the polyaluminum ferric sulfate sample.

[0070] The water purification agent prepared in this comparative example was tested for water treatment performance under the same test conditions, with a turbidity removal rate of 85.3%, a COD removal rate of 65.2%, and a total phosphorus removal rate of 86.5%.

[0071] Based on the test results provided in Examples 1-3 and Comparative Examples 1-3 above, this invention utilizes the synergistic effect of the built-in catalysts Mn, La, Ce, and Th in tailings and the optimized formulation of the iron-aluminum ratio to significantly improve the preparation efficiency and purification performance of the water purification agent.

[0072] To further characterize the composite water purifier prepared according to this invention, the composite water purifier prepared in Example 1, which has the best overall performance, was used as the test sample. The parameters of the oxidative polymerization reaction were compared, the chemical composition was detected, and the compatibility with various types of water bodies was tested. Specific test contents and results are as follows: (I) Comparison Test of Oxidative Polymerization Reaction Time To verify the promoting effect of the built-in manganese, lanthanum, cerium, and thorium catalytic system on the polymerization reaction, Example 1, Comparative Example 1, and Comparative Example 2 were selected for a reaction time versus degree of polymerization comparison experiment. The degree of polymerization was expressed as Fe... x (OH) γ The OH / Fe molar ratio was used for characterization. The higher the molar ratio, the higher the degree of polymerization of the water purification agent and the more complete the flocculation skeleton structure. The specific test results are shown in Table 1 below.

[0073] Table 1 Comparison of Oxidative Polymerization Reaction Time

[0074] As shown in Table 1, under the premise that all other preparation process parameters are completely consistent, Example 1, based on the Mn, La, Ce, and Th catalytic system built into pyrite tailings, has the fastest reaction rate, completing the polymerization reaction in just 2.5 hours, with a degree of polymerization as high as 0.68. Comparative Example 2, with the built-in catalytic elements removed, and Comparative Example 1, without any catalyst, have reaction times extended to 4.5 hours and 5.5 hours, respectively, with a significantly reduced degree of polymerization. This demonstrates that trace amounts of manganese, lanthanum, cerium, and thorium in tailings possess excellent synergistic catalytic activity, significantly accelerating the oxidation and hydrolysis polymerization of ferrous iron, shortening the production cycle, and effectively improving the degree of polymerization of the water purification agent and perfecting the flocculation framework structure.

[0075] (II) Chemical Composition Analysis of Water Purification Agent To clarify the internal elemental composition and trace catalytic element retention of the composite water purifier of this invention, inductively coupled plasma optical emission spectrometry (ICP-OES) was used to perform quantitative elemental analysis on the solid composite water purifier prepared in Example 1, accurately detecting the content of major and trace elements within the product. The results showed that the composite water purifier contained 18.5% Fe, 5.2% Al, 0.12% Mn, 18 mg / kg La, 15 mg / kg Ce, and 9 mg / kg Th. The aforementioned trace elements Mn, La, Ce, and Th are uniformly dispersed within the polymeric iron-aluminum framework structure, stably forming built-in catalytic active centers during the water purification process, ensuring the synergistic purification effect of coagulation, adsorption, and oxidation.

[0076] (III) Testing the effectiveness of appropriate treatment for different types of water bodies To verify the versatility and practical engineering application capability of the composite water purifier of this invention, treatment experiments were conducted on three typical polluted water bodies: domestic sewage, industrial wastewater, and landscape water bodies. The dosage of the water purifier was set differently according to the degree of pollution of different water bodies, and the stirring and sedimentation test conditions were uniform. The removal effect of pollutants in various water bodies was tested, and the specific test data are shown in Table 2 below.

[0077] Table 2 Treatment effects on different water bodies

[0078] As shown in Table 2, the composite water purifier prepared in this invention exhibits excellent adaptability to three typical water bodies: domestic sewage, industrial wastewater, and landscape water bodies. The dosage can be adjusted according to the different pollution loads of the water bodies, demonstrating flexible adaptability. For landscape water bodies with relatively low pollution levels, a low dosage of only 30 mg / L is sufficient for highly efficient purification, with turbidity, COD, and total phosphorus removal rates reaching 91%, 70%, and 92%, respectively. For conventional domestic sewage, stable treatment to standards can be achieved at a general dosage of 60 mg / L. For industrial wastewater with complex pollutants and higher concentrations, increasing the dosage to 120 mg / L further enhances the removal rates of turbidity, COD, and total phosphorus to 96%, 82%, and 97%, respectively, demonstrating stronger purification capabilities. Simultaneously, this water purifier exhibits good removal effects on heavy metal ions such as lead, copper, chromium, and zinc in water bodies, with heavy metal removal rates reaching 78%–85%. In summary, this composite water purifier has a wide range of applications and comprehensive purification functions. It can be used for conventional municipal sewage treatment, as well as to meet the purification and restoration needs of industrial wastewater and landscape water environments. It is highly versatile in engineering applications.

[0079] Therefore, this invention utilizes the Mn, La, Ce, and Th elements naturally present in pyrite tailings to construct a built-in synergistic catalytic system, significantly shortening the oxidative polymerization reaction time and increasing the degree of polymerization of the product without the need for an external catalyst. Simultaneously, by adjusting the iron-aluminum molar ratio, the coagulation framework structure of the water purification agent is optimized. The prepared composite water purification agent not only possesses excellent purification capabilities for conventional municipal sewage but is also adaptable to different water qualities such as industrial wastewater and landscape water bodies. It exhibits good removal effects on turbidity, organic matter, total phosphorus, and various heavy metal ions, demonstrating a wide range of applications and stable treatment results. Furthermore, it achieves solid waste resource utilization and low-cost water treatment, possessing high value for industrial application and promotion.

[0080] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0081] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings, characterized in that, Includes the following steps: S1. Pyrite tailings are crushed and screened to obtain tailings powder; S2. Add the tailings powder to a sulfuric acid solution with a mass concentration of 20%~60%, mix at a sulfuric acid solution to tailings powder liquid-solid ratio of 3~8:1mL / g, stir and react at 60~130℃ for 1~5h, and filter to obtain Fe-containing... 3+ Al 3+ Acid leaching solution; S3. Detect the iron and aluminum content in the acid leaching solution, and adjust the iron-aluminum molar ratio of the acid leaching solution to 0.5~5:1 based on the detection results; and the manganese, lanthanum, cerium and thorium elements contained in the acid leaching solution serve as built-in catalysts for the oxidative hydrolysis polymerization reaction; S4. Heat the adjusted acid leaching solution to 50~80℃ and carry out an oxidative hydrolysis polymerization reaction for 1~4 hours under stirring to obtain polyferric sulfate or polyaluminum ferric sulfate solution. S5. The polyferric sulfate or polyaluminum ferric sulfate solution is successively concentrated and dried to obtain a composite water purification agent.

2. The preparation method according to claim 1, characterized in that, In S1, the Fe content in the pyrite tailings is 20%~40%, the Al content is 3%~10%, the Mn content is 0.1%~0.5%, and the total content of La, Ce, and Th is 50~200ppm; the particle size of the tailings powder is no greater than 200 mesh.

3. The preparation method according to claim 1, characterized in that, In S1, after obtaining the tailings powder, the process further includes: separating the tailings powder into pyrite concentrate by magnetic separation or shaking table gravity separation, and using the remaining tailings powder for acid leaching reaction.

4. The preparation method according to claim 1, characterized in that, In S2, the mass concentration of the sulfuric acid solution is 30%~50%, the liquid-to-solid ratio is 4~6:1mL / g, the acid leaching reaction temperature is 80~110℃, and the reaction time is 2~4h.

5. The preparation method according to claim 1, characterized in that, In S3, the iron-aluminum molar ratio is adjusted to 1~3:1 by adding ferrous sulfate or aluminum sulfate.

6. The preparation method according to claim 1, characterized in that, In S4, the oxidative hydrolysis polymerization reaction is carried out by introducing air, oxygen or adding an oxidant. The oxidant is selected from one or more of sodium chlorate and hydrogen peroxide, and the amount of oxidant added is 0.5% to 8% of the mass of the acid leaching solution.

7. The preparation method according to claim 6, characterized in that, In S4, the oxidative hydrolysis polymerization reaction temperature is 60~70℃ and the reaction time is 2~3h.

8. The preparation method according to claim 1, characterized in that, In S5, the drying is spray drying or vacuum drying, the drying temperature is 80~120℃, and the product moisture content is ≤5%.

9. A manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The water purification agent uses ferric sulfate / aluminum sulfate as its active ingredient and contains catalytically active components such as manganese, lanthanum, cerium, and thorium.

10. The application of the manganese-lanthanum-cerium-thorium catalytic composite water purification agent based on pyrite tailings as described in claim 9 in water treatment, characterized in that, The composite water purification agent is added to the water body to be treated at a dosage of 10~200mg / L, stirred and mixed, and then allowed to settle for water treatment.

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