A method for arsenic removal from wastewater from non-ferrous metal smelting

Abstract

This application relates to the field of wastewater treatment, specifically disclosing a method for arsenic removal from non-ferrous metal smelting wastewater, comprising the following steps: I. Adding a catalyst and hydrogen peroxide to the non-ferrous metal smelting wastewater, followed by reaction at a temperature of 20-80℃ and a stirring rate of 250-400 r / min for 3-10 min to obtain pretreated wastewater; II. Adding lime to the pretreated wastewater, reacting at a temperature of 25-35℃ and a stirring rate of 250-400 r / min for 48-55 min, filtering to remove filter residue, and effluent, wherein the amount of lime added is 10-15 g / L. This application exhibits excellent arsenic removal capability. Experimental data proves that even for non-ferrous metal smelting wastewater with complex composition, this application can still successfully reduce the arsenic content in the wastewater to 0.35 mg / L or below, meeting stringent discharge standards.

Description

Technical Field

[0001] This application relates to the technical field of wastewater treatment, and in particular to a method for arsenic removal from wastewater from non-ferrous metal smelting. Background Technology

[0002] The main raw material for non-ferrous metal smelting is ore, and arsenic exists in the ore in the form of sulfides. When the ore is crushed (arsenic enters the wastewater during crushing and leaching; the acidic or alkaline solutions used in leaching can dissolve the arsenic in the ore, forming arsenic-containing wastewater), smelted, and refined (in the refining stage, chemical reagents are used to improve the purity of the metal, which also generates arsenic-containing wastewater), some arsenic dissolves or transforms into soluble forms, such as arsenates or arsenites, which are then discharged with the wastewater, forming arsenic-containing wastewater. Because arsenic and its compounds are highly toxic, they pose a serious threat to the environment and human health. Therefore, effective measures must be taken to treat arsenic-containing wastewater to meet national emission standards and protect the environment and human health. In my country, the emission standard for arsenic-containing wastewater stipulates that the content of arsenic and its compounds must not exceed 0.5 mg / L, and the concept of green development has become a trend of the times.

[0003] Currently, the main methods for arsenic removal from non-ferrous metal smelting wastewater include chemical precipitation, flocculation, extraction, adsorption, and microbial methods. Flocculation and adsorption are only suitable for treating low-concentration arsenic-containing systems. Microbial methods require stringent bacterial culture conditions and are not suitable for large-scale treatment. Extraction is too costly. Therefore, chemical precipitation is currently the most commonly used method, specifically involving the addition of lime to the water for neutralization, achieving an arsenic removal rate of up to 99%. However, since the quality of smelting wastewater varies from enterprise to enterprise, relying on a single arsenic removal method is insufficient for effective removal. Therefore, for complex smelting wastewater, multiple methods are often used in combination for arsenic removal. Existing combined methods involve aeration oxidation and lime neutralization. However, given the presence of various other metal ions in smelting wastewater, this combined method struggles to reduce the arsenic and its compounds in the effluent to 0.5 mg / L or below. Therefore, achieving efficient removal of arsenic from complex non-ferrous metal smelting wastewater has become a challenging problem. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for arsenic removal from wastewater from non-ferrous metal smelting.

[0005] This application provides a method for arsenic removal from wastewater from non-ferrous metal smelting, comprising the following steps:

[0006] I. Add a catalyst and hydrogen peroxide to wastewater from non-ferrous metal smelting, and then react for 3-10 minutes at a temperature of 20-80℃ and a stirring rate of 250-400 r / min to obtain pretreated wastewater. The catalyst includes a Cu-NaA zeolite catalyst, which is prepared by the following method:

[0007] Coal gangue was roasted to remove carbon, cooled, and then silicon dioxide was added for further roasting. Sodium hydroxide solution was added and mixed, the mixture was cooled and stirred, vacuum dried, heated and crystallized, filtered, washed with water, and dried to obtain NaA zeolite. This NaA zeolite was then added to a Cu(NO3)2·3H2O solution with a concentration of 0.5-1.5 g / L, aged, sonicated, crystallized, filtered, washed, dried, and ground to obtain Cu-NaA zeolite catalyst.

[0008] II. Add lime to the pretreated wastewater and react for 48-55 minutes at a temperature of 25-35℃ and a stirring rate of 250-400 r / min. After filtering to remove the filter residue, the water is discharged. The amount of lime added is 10-15 g / L.

[0009] By adopting the above technical solution, this application first utilizes coal gangue for roasting and carbon removal, then adds silica to adjust the silica-alumina ratio, and then adds sodium hydroxide for crystallization to obtain NaA zeolite, which has good adsorption and loading capacity. Subsequently, this application loads Cu onto NaA zeolite to obtain a Cu-NaA zeolite catalyst with good catalytic ability. Next, this application adds hydrogen peroxide to non-ferrous metal smelting wastewater for Fenton treatment, and uses the Cu-NaA zeolite catalyst as an auxiliary catalyst in the reaction. Since non-ferrous metal smelting wastewater contains complex metal ions, especially low-valence ions, the system can undergo a vigorous oxidation reaction, significantly reducing the number of low-valence ions and significantly increasing the number of high-valence ions, thereby mitigating the interference of low-valence metal ions on arsenic removal. Subsequently, this application adds lime to the pretreated wastewater that has undergone the Fenton reaction for neutralization and arsenic removal. The hydroxide ions in the lime can form colloids with the high-valence ions in the system, thereby forming flocculent coagulations with the arsenate ions in the system and precipitating them, thus achieving the purpose of efficient arsenic removal. More importantly, the Cu-NaA zeolite catalyst of this application not only possesses excellent catalytic ability but also exhibits good adsorption effects. When added to water, it not only catalyzes the Fenton reaction but also pre-adsorbs a portion of the arsenic before removal, thereby further enhancing the arsenic removal efficiency of this application. In summary, this application demonstrates excellent arsenic removal capability. Experimental data proves that even for complex non-ferrous metal smelting wastewater, this application can successfully reduce the arsenic content to 0.35 mg / L or below, meeting stringent discharge standards.

[0010] Preferably, in step I, the concentration of the Cu(NO3)2·3H2O solution is 1.2 g / L.

[0011] By adopting the above technical solution, this application strictly controls the concentration of Cu(NO3)2·3H2O solution, thereby controlling the Cu loading. At this point, the catalytic and adsorption effects of the Cu-NaA zeolite catalyst can achieve an optimal balance, further reducing the arsenic content in non-ferrous metal smelting wastewater. If the concentration of Cu(NO3)2·3H2O solution is too high, the number of adsorption channels on the NaA zeolite surface will decrease significantly, affecting the adsorption effect; if the concentration of Cu(NO3)2·3H2O solution is too low, its catalytic effect will be impaired, failing to significantly promote the intensity of the pretreatment reaction.

[0012] Preferably, in step I, the catalyst further includes Fe. 3+ - Montmorillonite carbon catalyst was prepared by the following method: Montmorillonite and sodium alginate were mixed in a weight ratio of 1:(0-2.5), calcined in an oxygen-free environment, and ground to obtain montmorillonite carbon. This carbon was then reacted with FeCl3·6H2O, and the solid was collected by filtration to obtain Fe... 3+ - Montmorillonite carbon catalyst.

[0013] Preferably, the Fe 3+ - The weight ratio of montmorillonite carbon catalyst to Cu-NaA zeolite catalyst is 1:(3.5-4).

[0014] By adopting the above technical solution, this application utilizes montmorillonite and sodium alginate to obtain montmorillonite carbon through blending, anaerobic calcination, and grinding. Then, ferric ions are loaded onto the carbon to obtain Fe3+ carbon, which possesses both adsorption and catalytic capabilities. 3+ - Montmorillonite carbon catalyst, sodium alginate can introduce a large number of hydroxyl and carboxyl groups, and together with montmorillonite, form a porous material with high surface area and large porosity through calcination. Fe 3+ - Montmorillonite carbon catalyst and Cu-NaA zeolite catalyst can exhibit good synergistic effects, due to Fe 3+ Montmorillonite-carbon catalysts possess excellent adsorption properties and a high specific surface area, effectively enriching low-valence metal ions in wastewater and promoting their oxidative transformation in the Fenton reaction, thus reducing the interference of these low-valence metal ions on the arsenic removal process. Simultaneously, the introduction of Cu-NaA zeolite catalysts enhances the system's catalytic activity, accelerating the decomposition of hydrogen peroxide to generate hydroxyl radicals and improving the overall redox capacity of the system. This combination not only improves wastewater treatment efficiency but also extends catalyst lifespan and reduces treatment costs.

[0015] Preferably, the Fe 3+The weight ratio of montmorillonite carbon catalyst to Cu-NaA zeolite catalyst is 1:3.75.

[0016] By adopting the above technical solution, this application enables Fe 3+ - A superior synergistic effect was formed between the montmorillonite carbon catalyst and the Cu-NaA zeolite catalyst, further improving the efficiency and stability of the Fenton reaction.

[0017] Preferably, the weight ratio of montmorillonite to sodium alginate is 1:2.

[0018] By adopting the above technical solution, this application strictly controls the weight ratio of montmorillonite to sodium alginate to be 1:2, so that the prepared Fe... 3+ Montmorillonite-carbon catalysts possess a more uniform structure and a higher active surface area, enhancing their adsorption capacity and catalytic efficiency. This further improves the rate and extent of conversion from low-valence metal ions to high-valence metal ions in the Fenton reaction, reduces the interference of low-valence metal ions on subsequent arsenic removal processes, and adsorbs more arsenic-containing ions from the water, thereby significantly reducing the arsenic content in the final effluent and achieving highly efficient arsenic removal.

[0019] Preferably, in step I, the temperature is 60°C.

[0020] By adopting the above technical solution, this application controls the temperature in non-ferrous metal smelting wastewater at 60℃, which helps promote the decomposition of hydrogen peroxide and the activity of the Cu-NaA zeolite catalyst, thereby enhancing the Fenton reaction effect. Under high temperature conditions, the chemical reaction rate in the system accelerates, making it easier for low-valence metal ions to be oxidized to high-valence states, further reducing the interference of these low-valence metal ions on the subsequent arsenic removal process and improving the arsenic removal efficiency. At the same time, a suitable temperature also helps to improve the adsorption performance of the adsorbent, ensuring a more stable and reliable wastewater treatment effect.

[0021] Preferably, in step I, the reaction time is 5 minutes.

[0022] By adopting the above technical solution, this application strictly controls the time of the Fenton reaction. The short-term strong oxidation reaction helps to rapidly reduce the number of low-valence ions in the system and promote the generation of high-valence ions, thereby reducing the interference of low-valence metal ions on the subsequent arsenic removal steps and ensuring efficient arsenic removal.

[0023] Preferably, in step II, the temperature is 30°C.

[0024] By adopting the above technical solution, this application strictly controls the temperature during neutralization and arsenic removal. This temperature can further optimize the reaction conditions while maintaining efficient arsenic removal, making the entire treatment process more stable and controllable. It can not only promote the formation of stable flocculent coagulants with lime and high-valence metal ions and arsenate in wastewater, but also effectively avoid the problem of increased energy consumption and reaction runaway caused by excessive temperature, ensuring that the arsenic content of the final effluent is consistently below 0.35 mg / L.

[0025] Preferably, in step II, the stirring rate is 300 r / min.

[0026] By adopting the above technical solution, this application strictly controls the stirring speed during neutralization and arsenic removal. This stirring speed helps to improve the contact efficiency between hydroxide ions and high-valence ions in the system, promotes the formation and stability of colloids, and thus more effectively combines with arsenate to form flocculent coagulants and precipitate, ultimately achieving a highly efficient arsenic removal effect.

[0027] In summary, this application has the following beneficial technical effects:

[0028] 1. The Cu-NaA zeolite catalyst prepared from coal gangue in this application not only has excellent catalytic ability but also pre-adsorbs some arsenic, significantly improving the effect of the Fenton reaction, efficiently oxidizing low-valence metal ions, and reducing their interference with the subsequent arsenic removal process; 2. In the wastewater pretreated by the Fenton reaction, the content of high-valence metal ions increases, which can form colloids with hydroxide ions in lime, further promoting the flocculation and precipitation of arsenate, so that the arsenic content in the final effluent is stably below 0.35 mg / L, meeting the national emission standards;

[0029] 3. By optimizing reaction conditions, such as temperature, stirring rate and reaction time, this application ensures the high efficiency and stability of the entire arsenic removal process, making it suitable for non-ferrous metal smelting wastewater with complex compositions and solving the problem that existing technologies cannot handle multi-component systems. Detailed Implementation

[0030] Material source

[0031] Unless otherwise specified, all raw materials used in this application are commercially available products, specifically:

[0032] The main components of coal gangue are SiO2 and Al2O3, accounting for 80.98 wt% of the total content, and the molar ratio of SiO2 to Al2O3 is 1.95.

[0033] Montmorillonite was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0034] The present application will be further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0035] Preparation Example 1.1

[0036] The preparation method of Cu-NaA zeolite catalyst includes the following steps:

[0037] Coal gangue was calcined at 550℃ for 2 hours for high-temperature decarbonization. After cooling, 2 kg of the calcined material was taken, and silicon dioxide was added to it to adjust the molar ratio of silicon dioxide to aluminum hydroxide to 2:1. It was then calcined in a muffle furnace at 750℃ for 2 hours. Subsequently, 7 g / mL sodium hydroxide solution was added and mixed, adjusting the molar ratio of sodium hydroxide to silicon dioxide to 2:1. The temperature was adjusted to 25℃, and the mixture was stirred for 12 hours. It was then vacuum dried, heated to 80℃ for crystallization for 24 hours, and naturally cooled. After washing with centrifugation and water until the pH was <11, it was dried in a drying oven to obtain NaA zeolite. All of it was transferred to a Cu(NO3)2·3H2O solution with a concentration of 1.5 g / L, aged for 2 hours, and ultrasonically treated at 25℃ for 30 minutes. It was then heated to 80℃ for crystallization for 6 hours, filtered, washed, dried, and ground to obtain Cu-NaA zeolite catalyst.

[0038] Preparation Example 1.2

[0039] The preparation method of Cu-NaA zeolite catalyst includes the following steps:

[0040] Coal gangue was calcined at 550℃ for 2 hours for high-temperature decarbonization. After cooling, 2 kg of the calcined material was taken, and silicon dioxide was added to it to adjust the molar ratio of silicon dioxide to aluminum hydroxide to 2:1. It was then calcined in a muffle furnace at 750℃ for 2 hours. Subsequently, 7 g / mL sodium hydroxide solution was added and mixed to adjust the molar ratio of sodium hydroxide to silicon dioxide to 2:1. The temperature was adjusted to 25℃, and the mixture was stirred for 12 hours. It was then vacuum dried, heated to 80℃ for crystallization for 24 hours, and naturally cooled. After washing with centrifugation and water until the pH was <11, it was dried in a drying oven to obtain NaA zeolite. All of it was transferred to a Cu(NO3)2·3H2O solution with a concentration of 0.5 g / L, aged for 2 hours, and ultrasonically treated at 25℃ for 30 minutes. It was then heated to 80℃ for crystallization for 6 hours, filtered, washed, dried, and ground to obtain Cu-NaA zeolite catalyst.

[0041] Preparation Example 2.1

[0042] The preparation method of Cu-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 0.8 g / L, while the rest is the same as in Preparation Example 1.1.

[0043] Preparation Example 2.2

[0044] The preparation method of Cu-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 1.0 g / L, while the rest are the same as in Preparation Example 1.1.

[0045] Preparation Example 2.3

[0046] The preparation method of Cu-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 1.2 g / L, while the rest are the same as in Preparation Example 1.1.

[0047] Preparation Example 3.1

[0048] Fe 3+ - A method for preparing montmorillonite carbon catalyst, comprising the following steps:

[0049] 1 kg of montmorillonite was dissolved in deionized water and ultrasonically stirred until homogeneous. Then, 2.5 kg of sodium alginate was added and stirred until a gel-like substance was formed. Next, 2% CaCl2 was added dropwise, stirring to form a hydrogel. The gel was then dried at 60°C and calcined in a tube furnace under anaerobic conditions at a heating rate of 10°C / min to 650°C for 2 hours to obtain montmorillonite char. The montmorillonite char was ground into powder and washed until neutral. 1 kg of the montmorillonite char powder was added to 2 L of water, followed by 2 kg of FeCl3·6H2O. After stirring for 12 hours, 0.5% NaOH solution was added dropwise until the pH reached 12. The mixture was then allowed to stand at 60°C for 24 hours, filtered, and the solid was collected and dried to obtain Fe. 3+ - Montmorillonite carbon catalyst.

[0050] Preparation Example 3.2

[0051] Fe 3+ - A method for preparing montmorillonite carbon catalyst, comprising the following steps:

[0052] Grind 1 kg of montmorillonite into powder and wash until neutral. Take 1 kg of montmorillonite char powder, add 2 L of water, then add 2 kg of FeCl3·6H2O. Stir for 12 h, then add 0.5% NaOH solution dropwise until the pH value equals 12. Then let it stand at 60℃ for 24 h, filter, collect the solid, and dry to obtain Fe. 3+ - Montmorillonite carbon catalyst.

[0053] Preparation Example 4.1

[0054] Fe 3+ The preparation method of the montmorillonite carbon catalyst differs from that of Preparation Example 3.1 in that the amount of sodium alginate used is 2 kg, while the rest are the same as those in Preparation Example 3.1.

[0055] Preparation Example 4.2

[0056] Fe 3+ The preparation method of the montmorillonite carbon catalyst differs from that of Preparation Example 3.1 in that the amount of sodium alginate used is 1.5 kg, while the rest are the same as those in Preparation Example 3.1.

[0057] Preparation Example 4.3

[0058] Fe 3+ The preparation method of the montmorillonite carbon catalyst differs from that of Preparation Example 3.1 in that the amount of sodium alginate used is 1.0 kg, while the rest are the same as those in Preparation Example 3.1.

[0059] Preparation Example 4.4

[0060] Fe 3+ The preparation method of the montmorillonite carbon catalyst differs from that of Preparation Example 3.1 in that the amount of sodium alginate used is 0.5 kg, while the rest are the same as those in Preparation Example 3.1.

[0061] Preparation Example 5.1

[0062] Fe 3+ The preparation method of the montmorillonite carbon catalyst differs from that of Preparation Example 3.1 in that FeCl3·6H2O is replaced with the same number of moles of Cu(NO3)2·3H2O, while the rest is the same as that of Preparation Example 3.1.

[0063] Preparation Example 5.2

[0064] Fe 3+ The preparation method of the montmorillonite carbon catalyst differs from that of Preparation Example 3.1 in that FeCl3·6H2O is replaced with the same number of moles of Co(NO3)26H2O, while the rest is the same as that of Preparation Example 3.1.

[0065] Comparative preparation example 1.1

[0066] The preparation method of Cu-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 0.3 g / L, while the rest is the same as in Preparation Example 1.1.

[0067] Comparative preparation example 1.2

[0068] The preparation method of Cu-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 2.0 g / L, while the rest is the same as in Preparation Example 1.1.

[0069] Comparative preparation example 1.3

[0070] The preparation method of Fe-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that Cu(NO3)2·3H2O solution is replaced with Fe(NO3)2·9H2O solution of the same concentration, while the rest is the same as that of Preparation Example 1.1.

[0071] Comparative preparation example 1.4

[0072] The preparation method of the La-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that the Cu(NO3)2·3H2O solution is replaced with a LaCl3 solution of the same concentration, while the rest is the same as that of Preparation Example 1.1.

[0073] Comparative preparation example 1.5

[0074] The preparation method of the Co-NaA zeolite catalyst differs from that of Preparation Example 1.1 in that the Cu(NO3)2·3H2O solution is replaced with a Co(NO3)2·6H2O solution of the same concentration, while the rest is the same as that of Preparation Example 1.1.

[0075] Example 1.1

[0076] A method for arsenic removal from wastewater from non-ferrous metal smelting includes the following steps:

[0077] 1. Add a catalyst (Cu-NaA zeolite catalyst prepared in Preparation Example 1.1) and hydrogen peroxide to non-ferrous metal smelting wastewater. The amount of catalyst added is 6 g / L and the amount of hydrogen peroxide added is 0.05 mol / L. Then react for 10 min at a temperature of 80℃ and a stirring rate of 250 r / min to obtain pretreated wastewater.

[0078] 2. Add lime to the pretreated wastewater, controlling the amount of lime added to be 10 g / L. React for 48 min at a temperature of 35℃ and a stirring rate of 250 r / min. After filtering to remove the filter residue, the wastewater is discharged.

[0079] Example 1.2

[0080] A method for arsenic removal from wastewater from non-ferrous metal smelting includes the following steps:

[0081] 1. Add a catalyst (Cu-NaA zeolite catalyst prepared in Preparation Example 1.2) and hydrogen peroxide to non-ferrous metal smelting wastewater. The amount of catalyst added is 6 g / L and the amount of hydrogen peroxide added is 0.05 mol / L. Then react for 3 min at a temperature of 20 °C and a stirring rate of 400 r / min to obtain pretreated wastewater.

[0082] 2. Add lime to the pretreated wastewater, controlling the amount of lime added to be 15g / L. React for 55min at a temperature of 25℃ and a stirring rate of 400r / min. After filtering to remove the filter residue, the wastewater is discharged.

[0083] Example 1.3

[0084] A method for arsenic removal from wastewater from non-ferrous metal smelting includes the following steps:

[0085] 1. Add a catalyst (Cu-NaA zeolite catalyst prepared in Preparation Example 1.1) and hydrogen peroxide to non-ferrous metal smelting wastewater. The amount of catalyst added is 6 g / L and the amount of hydrogen peroxide added is 0.05 mol / L. Then react for 5 min at a temperature of 60 °C and a stirring rate of 250 r / min to obtain pretreated wastewater.

[0086] 2. Add lime to the pretreated wastewater, controlling the amount of lime added to be 10g / L. React for 48min at a temperature of 30℃ and a stirring rate of 300r / min. After filtering to remove the filter residue, the wastewater is discharged.

[0087] Examples 2.1-2.3

[0088] A method for arsenic removal from wastewater from non-ferrous metal smelting differs from Example 1.3 in that: in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is replaced with the Cu-NaA zeolite catalyst prepared in Preparation Examples 2.1-2.3, while the rest is the same as in Preparation Example 1.3.

[0089] Example 3.1

[0090] A method for removing arsenic from wastewater from non-ferrous metal smelting differs from Example 1.3 in that: in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is replaced with a mixture of Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 and Fe2O3 zeolite catalyst prepared in Preparation Example 3.1 at a weight ratio of 1:3.5. 3+ - Montmorillonite carbon catalyst, the rest are the same as in Preparation Example 1.3.

[0091] Example 3.2

[0092] A method for removing arsenic from wastewater from non-ferrous metal smelting differs from Example 1.3 in that, in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is replaced with a mixture of the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 and the Fe zeolite catalyst prepared in Preparation Example 3.2 at a weight ratio of 1:4. 3+ - Montmorillonite carbon catalyst, the rest are the same as in Preparation Example 1.3.

[0093] Example 3.3

[0094] A method for removing arsenic from wastewater from non-ferrous metal smelting differs from Example 3.1 in that: in step I, the Cu-NaA zeolite catalyst prepared in Example 1.1 and the Fe2O3 catalyst prepared in Example 3.1 are used. 3+ - The weight ratio of montmorillonite to carbon catalyst was 1:3.75, and all other aspects were the same as in Preparation Example 3.1.

[0095] Examples 4.1-4.4

[0096] A method for removing arsenic from wastewater from non-ferrous metal smelting differs from Example 3.3 in that: in step I, the Fe prepared in Example 3.1 is... 3+ - The montmorillonite carbon catalyst was replaced with the Fe prepared in Examples 4.1-4.4, respectively. 3+ - Montmorillonite carbon catalyst, the rest are the same as in Preparation Example 3.1.

[0097] Comparative Examples 1.1-1.5

[0098] The difference from Example 1.3 is that in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 was replaced with the catalyst prepared in Comparative Preparation Examples 1.1-1.5, and the rest was the same as in Preparation Example 3.1.

[0099] Comparative Example 2.1

[0100] The difference from Example 1.3 is that step I is removed. Specifically, lime is added to the non-ferrous metal smelting wastewater, and the amount of lime added is controlled at 50 g / L. The mixture is reacted for 48 min at a temperature of 50°C and a stirring rate of 300 r / min. After filtering to remove the filter residue, the water is discharged.

[0101] Comparative Example 2.2

[0102] The difference from Example 1.3 is that step I is removed. Specifically, lime is added to the non-ferrous metal smelting wastewater, and the amount of lime added is controlled at 10 g / L. The mixture is reacted for 48 min at a temperature of 30°C and a stirring rate of 300 r / min. After filtering to remove the filter residue, the water is discharged.

[0103] Comparative Example 3

[0104] The difference from Example 1.3 is that in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 was completely replaced with ferrous sulfate, while the rest was the same as in Example 1.3.

[0105] Performance testing

[0106] The arsenic content in the effluent was determined by inductively coupled plasma mass spectrometry. The total arsenic content in the non-ferrous metal smelting wastewater of this application was 180 mg / L. The removal rate was calculated, and the removal rate and the arsenic content in the effluent were recorded in Table 1.

[0107] Table 1 Performance Test Table

[0108] Group Arsenic content in effluent (mg / L) Removal rate % Example 1.1 0.35 99.806 Example 1.2 0.34 99.811 Example 1.3 0.31 99.828 Example 2.1 0.30 99.833 Example 2.2 0.31 99.828 Example 2.3 0.24 99.867 Example 3.1 0.19 99.894 Example 3.2 0.21 99.883 Example 3.3 0.15 99.917 Example 4.1 0.16 99.911 Example 4.2 0.15 99.917 Example 4.3 0.12 99.933 Example 4.4 0.15 99.917 Comparative Example 1.1 0.63 99.650 Comparative Example 1.2 0.60 99.667 Comparative Example 1.3 0.85 99.528 Comparative Example 1.4 0.78 99.567 Comparative Example 1.5 0.82 99.544 Comparative Example 2.1 0.96 99.467 Comparative Example 2.2 1.34 99.256 Comparative Example 3 0.59 99.672

[0109] Data Analysis:

[0110] As can be seen from Table 1, the arsenic removal treatment method of Examples 1.1-1.2 of this application can remove more than 99.806% of the arsenic in non-ferrous metal smelting wastewater with a total arsenic content of 180 mg / L, and the arsenic content in the final effluent is no higher than 0.35 mg / L. This proves that by adding hydrogen peroxide to the non-ferrous metal smelting wastewater for Fenton treatment, using Cu-NaA zeolite catalyst as a catalyst to assist the reaction, and then adding lime to the pretreated wastewater that has undergone the Fenton reaction for neutralization and arsenic removal, the arsenic content of the complex non-ferrous metal smelting wastewater can be reduced to 0.35 mg / L or below, meeting the strict emission standards.

[0111] The difference between Example 1.3 and Example 1.1 lies in the optimization of various treatment process parameters. Data shows that the arsenic removal rate in the non-ferrous metal smelting wastewater of Example 1.3 was 99.828%, and the final arsenic content in the effluent was 0.31 mg / L. This proves that by strictly controlling the temperature and reaction time in step I, and the temperature and stirring speed in step II, this application further reduced the interference of low-valence metal ions on the subsequent arsenic removal process. The short-term strong oxidation reaction helps to rapidly and significantly reduce the number of low-valence ions in the system, promotes the generation of high-valence ions, and makes the entire treatment process more stable and controllable. It can not only promote the formation of stable flocculants between lime and high-valence metal ions and arsenate in wastewater, but also effectively avoid the problems of increased energy consumption and reaction runaway caused by excessive temperature. It improves the contact efficiency between hydroxide ions and high-valence ions in the system, promotes the formation and stabilization of colloids, and thus more effectively combines with arsenate to form flocculants and precipitate, ultimately achieving a highly efficient arsenic removal effect.

[0112] The difference between Examples 2.1-2.3 and Example 1.3 lies in the different Cu-NaA zeolite catalysts. Data shows that Example 2.3 exhibits the highest arsenic removal rate and the lowest arsenic content in the final effluent from non-ferrous metal smelting wastewater. This demonstrates that by strictly controlling the concentration of the Cu(NO3)2·3H2O solution, the loading of Cu is controlled. At this point, the catalytic and adsorption effects of the Cu-NaA zeolite catalyst achieve an optimal balance, further reducing the arsenic content in non-ferrous metal smelting wastewater. If the concentration of the Cu(NO3)2·3H2O solution is too high, the number of adsorption channels on the NaA zeolite surface will decrease significantly, affecting the adsorption effect; if the concentration of the Cu(NO3)2·3H2O solution is too low, its catalytic effect is impaired, failing to significantly promote the intensity of the pretreatment reaction.

[0113] The difference between Examples 3.1-3.3 and Example 1.3 is that Fe was also added. 3+ - Montmorillonite carbon catalyst. Data shows that the arsenic removal rate in non-ferrous metal smelting wastewater in Examples 3.1-3.2 was improved, and the arsenic content in the final effluent was reduced, proving that the Fe... 3+ - Montmorillonite carbon catalyst and Cu-NaA zeolite catalyst can exhibit good synergistic effects, due to Fe 3+ Montmorillonite carbon catalysts possess excellent adsorption properties and a high specific surface area, enabling them to effectively enrich low-valence metal ions in wastewater, promote their oxidative transformation in the Fenton reaction, and reduce the interference of these low-valence metal ions on the arsenic removal process. At the same time, the introduction of Cu-NaA zeolite catalysts enhances the catalytic activity of the system, accelerates the decomposition of hydrogen peroxide to generate hydroxyl radicals, and improves the redox capacity of the entire system.

[0114] The difference between Examples 4.1-4.4 and Example 3.3 lies in Fe. 3+ - The montmorillonite-carbon catalysts differ, with Example 4.3 showing the highest arsenic removal rate and lowest arsenic content in the final effluent from non-ferrous metal smelting wastewater. This demonstrates that the application, by strictly maintaining a montmorillonite to sodium alginate weight ratio of 1:2, ensures the preparation of Fe... 3+ Montmorillonite-carbon catalysts possess a more uniform structure and a higher active surface area, enhancing their adsorption capacity and catalytic efficiency. This further improves the rate and extent of conversion from low-valence metal ions to high-valence metal ions in the Fenton reaction, reduces the interference of low-valence metal ions on subsequent arsenic removal processes, and adsorbs more arsenic-containing ions from the water, thereby significantly reducing the arsenic content in the final effluent and achieving highly efficient arsenic removal.

[0115] The difference between Comparative Examples 1.1-1.2 and Example 1.3 lies in the concentration of the Cu(NO3)2·3H2O solution used in the preparation of the Cu-NaA zeolite catalyst. Data shows that the arsenic removal rate in the non-ferrous metal smelting wastewater of Comparative Examples 1.1-1.2 was significantly reduced, while the arsenic content in the final effluent was significantly increased. This demonstrates that by strictly controlling the concentration of the Cu(NO3)2·3H2O solution, the loading of Cu was controlled. At this point, the catalytic and adsorption effects of the Cu-NaA zeolite catalyst achieved an optimal balance, further reducing the arsenic content in the non-ferrous metal smelting wastewater. If the concentration of the Cu(NO3)2·3H2O solution is too high, the number of adsorption channels on the NaA zeolite surface will be significantly reduced, affecting the adsorption effect; if the concentration of the Cu(NO3)2·3H2O solution is too low, its catalytic effect is impaired, failing to significantly promote the intensity of the pretreatment reaction.

[0116] The difference between Comparative Examples 1.3-1.5 and Example 1.3 is that, in preparing the Cu-NaA zeolite catalyst used in these examples, the Cu(NO3)2·3H2O solution was replaced with Fe(NO3)2·9H2O solution, LaCl3 solution, and Co(NO3)2·6H2O solution, respectively. Data shows that the arsenic removal rate in the non-ferrous metal smelting wastewater of Comparative Examples 1.3-1.5 was significantly reduced, and the arsenic content in the final effluent was significantly increased. This proves that the Cu-NaA zeolite catalyst of this application not only has excellent catalytic ability but also good adsorption effect. After being added to the water body, it can not only catalyze the Fenton reaction but also pre-adsorb some arsenic before arsenic removal, thereby further improving the arsenic removal effect of this application.

[0117] The difference between Comparative Example 2.1 and Example 1.3 is that step I was removed, and all process parameters in step II were optimized. The difference between Comparative Example 2.2 and Example 1.3 is that step I was removed. The results show that the arsenic removal rate in the non-ferrous metal smelting wastewater of Comparative Example 2.1 and Comparative Example 2.2 was significantly reduced, and the arsenic content in the final effluent was also significantly increased. This proves that by adding hydrogen peroxide to the non-ferrous metal smelting wastewater for Fenton treatment and using Cu-NaA zeolite catalyst as a catalyst to assist the reaction, the arsenic removal rate can be greatly improved, achieving a highly efficient arsenic removal effect.

[0118] The difference between Comparative Example 3 and Example 1.3 is that the Cu-NaA zeolite catalyst was completely replaced with ferrous sulfate. Data shows that the arsenic removal rate in the non-ferrous metal smelting wastewater of Comparative Example 3 was significantly reduced, and the arsenic content in the final effluent was significantly increased. This proves that the Cu-NaA zeolite catalyst of this application not only has excellent catalytic ability, but also has good adsorption effect. After being added to the water body, it can not only catalyze the Fenton reaction, but also pre-adsorb some arsenic before arsenic removal, thereby further improving the arsenic removal effect of this application.

[0119] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for arsenic removal treatment of wastewater from non-ferrous metal smelting, characterized in that, Includes the following steps: I. Add a catalyst and hydrogen peroxide to wastewater from non-ferrous metal smelting, and then react for 3-10 minutes at a temperature of 20-80℃ and a stirring rate of 250-400 r / min to obtain pretreated wastewater. The catalyst includes a Cu-NaA zeolite catalyst, which is prepared by the following method: Coal gangue was roasted to remove carbon, cooled, and then silicon dioxide was added for further roasting. Sodium hydroxide solution was added and mixed, the mixture was cooled and stirred, vacuum dried, heated and crystallized, filtered, washed with water, and dried to obtain NaA zeolite. This NaA zeolite was then added to a Cu(NO3)2·3H2O solution with a concentration of 0.5-1.5 g / L, aged, sonicated, crystallized, filtered, washed, dried, and ground to obtain Cu-NaA zeolite catalyst. The catalyst also includes Fe 3+ - Montmorillonite carbon catalyst, prepared by the following method: Montmorillonite and sodium alginate were mixed in a weight ratio of 1:(0-2.5), calcined in an oxygen-free environment, and ground to obtain montmorillonite char. This char was then reacted with FeCl3·6H2O, and the solid was collected by filtration to obtain Fe... 3+ - Montmorillonite carbon catalyst; II. Add lime to the pretreated wastewater and react for 48-55 minutes at a temperature of 25-35℃ and a stirring rate of 250-400 r / min. After filtering to remove the filter residue, the water is discharged. The amount of lime added is 10-15 g / L.

2. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 1, characterized in that, In step I, the concentration of the Cu(NO3)2·3H2O solution is 1.2 g / L.

3. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 1, characterized in that, The Fe 3 + - The weight ratio of montmorillonite carbon catalyst to Cu-NaA zeolite catalyst is 1:(3.5-4).

4. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 3, characterized in that, The Fe 3 + The weight ratio of montmorillonite carbon catalyst to Cu-NaA zeolite catalyst is 1:3.

75.

5. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 1, characterized in that, The weight ratio of montmorillonite to sodium alginate is 1:

2.

6. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 1, characterized in that, In step I, the temperature is 60°C.

7. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 1, characterized in that, In step I, the reaction time is 5 minutes.

8. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 1, characterized in that, In step II, the temperature is 30°C.

9. The method for arsenic removal treatment of non-ferrous metal smelting wastewater according to claim 1, characterized in that, In step II, the stirring rate is 300 r / min.