Arsenic removal treatment method for non-ferrous metal smelting sewage

Abstract

The invention relates to the field of sewage treatment, and particularly discloses a non-ferrous metal smelting sewage arsenic removal treatment method which comprises the following steps: I, adding a catalyst and hydrogen peroxide into non-ferrous metal smelting sewage, and then reacting for 3-10 minutes under the conditions that the temperature is 20-80 DEG C and the stirring speed is 250-400 r / min to obtain pretreated sewage; and II, lime is added into the pretreated sewage, a reaction is performed for 48-55 min under the conditions that the temperature is 25-35 DEG C and the stirring speed is 250-400 r / min, filtering is performed to remove filter residues, then water is discharged, and the adding amount of the lime is 10-15 g / L. According to the present invention, the arsenic removal agent has excellent arsenic removal ability, and the experimental data proves that the arsenic content in the non-ferrous metal smelting sewage with complex components can be smoothly reduced to 0.35 mg / L or less so as to meet the strict emission standard.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to a method for removing arsenic from sewage from non-ferrous metal smelting. Background Art

[0002] The main raw material for non-ferrous metal smelting is ore, and the element arsenic exists in the ore in the form of sulfide. When the ore is crushed (arsenic enters the wastewater during the crushing and leaching process of the ore. The acidic or alkaline solution used in the leaching process can dissolve the arsenic in the ore to form arsenic-containing wastewater), smelted and refined (in the refining stage of the metal, in order to improve the purity of the metal, chemical reagents will be used for treatment, and arsenic-containing wastewater will be produced in this process), part of the arsenic will dissolve or be converted into soluble forms, such as arsenate or arsenite, and form arsenic-containing wastewater with the wastewater discharge. 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 the national emission standards and protect the environment and human health. In my country, the emission standards for arsenic-containing wastewater stipulate that the content of arsenic and its compounds shall not exceed 0.5 mg / L. The concept of green development has become the trend of the times.

[0003] At present, the arsenic removal treatment methods for non-ferrous metal smelting wastewater mainly include chemical precipitation, flocculation, extraction, adsorption and microbial methods. Among them, flocculation and adsorption are only suitable for the treatment of low-concentration arsenic systems. The bacterial culture conditions in the microbial method are relatively harsh and not suitable for large-scale treatment. The implementation cost of the extraction method is too high. Therefore, the most commonly used treatment method is chemical precipitation. Specifically, lime is added to the water body for neutralization reaction, and the arsenic removal rate can reach 99%. However, since the water quality of smelting wastewater generated by each enterprise is different, relying on a single arsenic removal method cannot achieve the purpose of effective arsenic removal. Therefore, for smelting wastewater with complex components, multiple methods are often used for combined arsenic removal. The existing combined method is a combination of aeration oxidation and lime neutralization. However, in the face of the presence of multiple other metal ions in smelting wastewater, this combined method is also difficult to reduce the content of arsenic and its compounds in the effluent to 0.5 mg / L or less. Therefore, how to achieve efficient removal of arsenic in non-ferrous metal smelting wastewater with complex components has become a more difficult problem. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a method for removing arsenic from non-ferrous metal smelting wastewater.

[0005] The present application provides a method for removing arsenic from non-ferrous metal smelting wastewater, comprising the following steps: I. Adding a catalyst and hydrogen peroxide to non-ferrous metal smelting wastewater, and then reacting for 3-10 minutes at a temperature of 20-80° C. and a stirring rate of 250-400 r / min to obtain pretreated wastewater, wherein the catalyst includes a Cu-NaA zeolite catalyst, which is prepared by the following method: The coal gangue is roasted to remove carbon, and after cooling, silicon dioxide is added to continue roasting, and sodium hydroxide solution is added to blend, the temperature is lowered and stirred, vacuum dried, the temperature is increased for crystallization, filtered, washed with water, and dried to obtain NaA zeolite, which is added to a Cu(NO3)2·3H2O solution with a concentration of 0.5-1.5 g / L, aged, ultrasonicated, crystallized, filtered, washed, dried, and ground to obtain a Cu-NaA zeolite catalyst; II. Add lime to the pretreated sewage, react for 48-55 minutes at a temperature of 25-35°C and a stirring rate of 250-400r / min, filter and remove the residue to discharge the water, and the amount of lime added is 10-15g / L.

[0006] By adopting the above technical scheme, the present application first uses coal gangue for roasting and decarbonization, then adds silicon dioxide to adjust the silicon-aluminum ratio, and then adds sodium hydroxide for crystallization to obtain NaA zeolite, which has good adsorption capacity and loading capacity. Subsequently, the present application loads Cu on NaA zeolite to obtain a Cu-NaA zeolite catalyst with good catalytic ability. Next, the present application adds hydrogen peroxide to the non-ferrous metal smelting wastewater for Fenton treatment, and uses the Cu-NaA zeolite catalyst as a catalyst-assisted reaction. Since the non-ferrous metal smelting wastewater contains metal ions with complex components, especially low-valent ions, the system can undergo a violent oxidation reaction, greatly reducing the number of low-valent ions in the system and greatly increasing the number of high-valent ions, thereby reducing the interference of low-valent metal ions with arsenic removal. Subsequently, the present 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-valent ions in the system, thereby forming flocculent coagulants and precipitating with the arsenate in the system, thereby achieving the purpose of efficient arsenic removal. More importantly, the Cu-NaA zeolite catalyst of the present application not only has excellent catalytic ability, but also has good adsorption effect. After being put into the water body, it can not only catalyze the Fenton reaction, but also pre-adsorb a part of arsenic before arsenic removal, thereby further improving the arsenic removal effect of the present application. In summary, the present application has a very excellent arsenic removal ability. Experimental data prove that for non-ferrous metal smelting wastewater with complex components, the present application can still successfully reduce the arsenic content in non-ferrous metal smelting wastewater to 0.35 mg / L and below, meeting strict emission standards.

[0007] Preferably, in step I, the concentration of the Cu(NO3)2·3H2O solution is 1.2 g / L.

[0008] By adopting the above technical solution, the present application strictly controls the concentration of the Cu(NO3)2·3H2O solution, thereby controlling the Cu loading amount. At this time, the catalytic effect and adsorption effect 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 the Cu(NO3)2·3H2O solution is too high, the number of adsorption channels on the surface of the NaA zeolite will be greatly reduced, affecting the adsorption effect; if the concentration of the Cu(NO3)2·3H2O solution is too low, its catalytic effect will be impaired, and it will not be able to significantly promote the intensity of the pretreatment reaction.

[0009] Preferably, in step I, the catalyst further comprises Fe 3+ -montmorillonite charcoal catalyst, prepared by the following method: montmorillonite and sodium alginate are mixed in a weight ratio of 1: (0-2.5), calcined in the absence of oxygen, and ground to obtain montmorillonite charcoal, which is then mixed with FeCl3·6H2O for reaction, and the solid is collected by filtration to obtain Fe 3+ -Montmorillonite carbon catalyst.

[0010] Preferably, the Fe 3+ -The weight ratio of montmorillonite carbon catalyst to Cu-NaA zeolite catalyst is 1:(3.5-4).

[0011] By adopting the above technical scheme, the present invention uses montmorillonite and sodium alginate to mix, calcine without oxygen, grind, obtain montmorillonite charcoal, and then load trivalent iron ions on it to obtain Fe with both adsorption and catalytic ability. 3+ -Montmorillonite carbon catalyst, sodium alginate can introduce a large number of hydroxyl and carboxyl groups, and form a porous material with high surface area and large porosity through calcination with montmorillonite. 3+ -Montmorillonite carbon catalyst and Cu-NaA zeolite catalyst can play a good synergistic effect, because Fe 3+ -Montmorillonite carbon catalyst has excellent adsorption performance and high specific surface area, which can effectively enrich low-valent metal ions in sewage, promote their oxidation transformation in Fenton reaction, and reduce the interference of these low-valent metal ions in the arsenic removal process; at the same time, the introduction of Cu-NaA zeolite catalyst enhances the catalytic activity of the system, accelerates the process of hydrogen peroxide decomposition to generate hydroxyl radicals, and improves the redox capacity of the entire system. This combination not only improves the effect of sewage treatment, but also prolongs the service life of the catalyst and reduces the treatment cost.

[0012] Preferably, the Fe 3+-The weight ratio of montmorillonite carbon catalyst to Cu-NaA zeolite catalyst is 1:3.75.

[0013] By adopting the above technical solution, the present invention makes Fe 3+ -The montmorillonite carbon catalyst and the Cu-NaA zeolite catalyst formed a more excellent synergistic effect, further improving the efficiency and stability of the Fenton reaction.

[0014] Preferably, the weight ratio of montmorillonite to sodium alginate is 1:2.

[0015] By adopting the above technical solution, the present invention strictly controls the weight ratio of montmorillonite to sodium alginate to be 1:2, so that the prepared Fe 3+ -Montmorillonite carbon catalyst has a more uniform structure and a higher active surface area, which enhances the adsorption capacity and catalytic efficiency of the catalyst. This further improves the rate and degree of conversion of low-valent metal ions to high-valent metal ions in the Fenton reaction, reduces the interference of low-valent metal ions on the subsequent arsenic removal process, and adsorbs more arsenic-containing ions in the water body, thereby significantly reducing the arsenic content in the final effluent, achieving the effect of efficient arsenic removal.

[0016] Preferably, in step I, the temperature is 60°C.

[0017] By adopting the above technical solution, the present application controls the temperature in non-ferrous metal smelting wastewater at 60°C, which helps promote the decomposition of hydrogen peroxide and the activity of the Cu-NaA zeolite catalyst, thereby enhancing the effect of the Fenton reaction. Under high temperature conditions, the chemical reaction rate in the system is accelerated, making it easier for low-valent metal ions to be oxidized to high-valent states, further reducing the interference of these low-valent metal ions with the subsequent arsenic removal process and improving the arsenic removal efficiency. At the same time, the appropriate temperature also helps to improve the adsorption performance of the adsorbent, ensuring that the sewage treatment effect is more stable and reliable.

[0018] Preferably, in step I, the reaction is performed for 5 min.

[0019] By adopting the above technical scheme, the present application strictly controls the time of the Fenton reaction. The short-term strong oxidation reaction helps to quickly reduce the number of low-valent ions in the system and promote the generation of high-valent ions, thereby reducing the interference of low-valent metal ions on subsequent arsenic removal steps and ensuring efficient arsenic removal.

[0020] Preferably, in step II, the temperature is 30°C.

[0021] By adopting the above technical scheme, the present 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 high-valent metal ions and arsenate in the lime and sewage, but also effectively avoid the increase in energy consumption and reaction runaway caused by excessively high temperature, ensuring that the arsenic content of the final effluent is stably lower than 0.35 mg / L.

[0022] Preferably, in step II, the stirring rate is 300 r / min.

[0023] By adopting the above technical scheme, the present application strictly controls the stirring speed during neutralization and arsenic removal, which helps to improve the contact efficiency between hydroxide ions and high-valent ions in the system, promote the formation and stability of colloids, and thus more effectively combine with arsenate to form flocculent coagulants and precipitate, ultimately achieving an efficient arsenic removal effect.

[0024] In summary, this application has the following beneficial technical effects: 1. The Cu-NaA zeolite catalyst prepared by using coal gangue in the present application not only has excellent catalytic ability, but also can pre-adsorb part of arsenic, significantly improving the effect of Fenton reaction, efficiently oxidizing low-valent metal ions, and reducing their interference with the subsequent arsenic removal process; 2. In the sewage pretreated by Fenton reaction in the present application, the content of high-valent 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 lower than 0.35 mg / L, meeting the national emission standards; 3. This application ensures the efficiency and stability of the entire arsenic removal process by optimizing reaction conditions such as temperature, stirring rate and reaction time. It is suitable for non-ferrous metal smelting wastewater with complex components and solves the problem that existing technologies are difficult to deal with multi-component systems. DETAILED DESCRIPTION

[0025] Material Source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: The main components of coal gangue are SiO2 and Al2O3, accounting for 80.98wt% of the total content, and the molar ratio of SiO2 to Al2O3 is 1.95; Montmorillonite was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0026] The present application is further described in detail below in combination with preparation examples, embodiments and comparative examples.

[0027] Preparation Example 1.1 The preparation method of Cu-NaA zeolite catalyst comprises the following steps: The gangue was calcined at 550°C for 2h for high-temperature decarbonization. After cooling, 2kg of the calcined material was taken and silica was added thereto to adjust the molar ratio of silica to aluminum hydroxide to 2:1. The material was then calcined at 750°C for 2h in a muffle furnace. Subsequently, 7g / mL of sodium hydroxide solution was added and blended to adjust the molar ratio of sodium hydroxide to silica to 2:1. The temperature was adjusted to 25°C, stirred for 12h, vacuum dried, heated to 80°C for crystallization for 24h, cooled naturally, washed by centrifugation and water washing until pH <11, dried in a drying oven to obtain NaA zeolite, and all of it was transferred to a Cu(NO3)2·3H2O solution with a concentration of 1.5g / L, aged for 2h, and ultrasonically treated at 25°C for 30min, heated to 80°C for crystallization for 6h, filtered, washed, dried, and ground to obtain a Cu-NaA zeolite catalyst.

[0028] Preparation Example 1.2 The preparation method of Cu-NaA zeolite catalyst comprises the following steps: The coal gangue was roasted at 550°C for 2h for high-temperature decarbonization. After cooling, 2kg of the roasted material was taken and silica was added thereto to adjust the molar ratio of silica to aluminum hydroxide to 2:1. The material was then roasted at 750°C for 2h in a muffle furnace. Subsequently, 7g / mL of sodium hydroxide solution was added and blended to adjust the molar ratio of sodium hydroxide to silica to 2:1. The temperature was adjusted to 25°C, stirred for 12h, vacuum dried, heated to 80°C for crystallization for 24h, cooled naturally, washed by centrifugation and water washing until pH <11, dried in a drying oven to obtain NaA zeolite, and all of it was transferred to a Cu(NO3)2·3H2O solution with a concentration of 0.5g / L, aged for 2h, and ultrasonically treated at 25°C for 30min, heated to 80°C for crystallization for 6h, filtered, washed, dried, and ground to obtain a Cu-NaA zeolite catalyst.

[0029] Preparation Example 2.1 The preparation method of Cu-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 0.8 g / L, and the rest is the same as Preparation Example 1.1.

[0030] Preparation Example 2.2 The preparation method of Cu-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 1.0 g / L, and the rest is the same as Preparation Example 1.1.

[0031] Preparation Example 2.3 The preparation method of Cu-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 1.2 g / L, and the rest is the same as Preparation Example 1.1.

[0032] Preparation Example 3.1 Fe 3+ - A method for preparing a montmorillonite carbon catalyst, comprising the following steps: 1 kg of montmorillonite was dissolved in deionized water, and 2.5 kg of sodium alginate was added after ultrasonic stirring. After stirring into a colloid, 2% CaCl2 was added dropwise and stirred to form a hydrogel. Then, the mixture was dried at 60 °C and placed in a tube furnace in an oxygen-free environment. The temperature was raised to 650 °C at a rate of 10 °C / min and calcined for 2 h to obtain montmorillonite charcoal. The obtained montmorillonite charcoal was ground into powder and washed to neutrality. 1 kg of montmorillonite charcoal powder was added to 2 L of water and 2 kg of FeCl3·6H2O. After stirring for 12 h, 0.5% NaOH solution was added dropwise until the pH value was equal to 12. The mixture was then allowed to stand at 60 °C for 24 h, filtered, the solid was collected, and dried to obtain Fe 3+ -Montmorillonite carbon catalyst.

[0033] Preparation Example 3.2 Fe 3+ - A method for preparing a montmorillonite carbon catalyst, comprising the following steps: 1 kg of montmorillonite was ground into powder and washed to neutrality. 1 kg of montmorillonite charcoal powder was added to 2 L of water and 2 kg of FeCl3·6H2O. After stirring for 12 h, 0.5% NaOH solution was added dropwise until the pH value was equal to 12. Then, the mixture was allowed to stand at 60 ° C for 24 h, filtered, the solid was collected, and dried to obtain Fe 3+ -Montmorillonite carbon catalyst.

[0034] Preparation Example 4.1 Fe 3+ -The preparation method of montmorillonite carbon catalyst is different from that of Preparation Example 3.1 in that the amount of sodium alginate used is 2 kg, and the rest is the same as Preparation Example 3.1.

[0035] Preparation Example 4.2 Fe 3+ -The preparation method of montmorillonite carbon catalyst is different from that of Preparation Example 3.1 in that the amount of sodium alginate used is 1.5 kg, and the rest is the same as Preparation Example 3.1.

[0036] Preparation Example 4.3 Fe 3+ -The preparation method of montmorillonite carbon catalyst is different from that of Preparation Example 3.1 in that the amount of sodium alginate used is 1.0 kg, and the rest is the same as that of Preparation Example 3.1.

[0037] Preparation Example 4.4 Fe 3+ -The preparation method of montmorillonite carbon catalyst is different from that of Preparation Example 3.1 in that the amount of sodium alginate used is 0.5 kg, and the rest is the same as Preparation Example 3.1.

[0038] Preparation Example 5.1 Fe 3+ -The preparation method of montmorillonite carbon catalyst is different from that of Preparation Example 3.1 in that FeCl3·6H2O is replaced by the same molar number of Cu(NO3)2·3H2O, and the rest is the same as Preparation Example 3.1.

[0039] Preparation Example 5.2 Fe 3+ -The preparation method of montmorillonite carbon catalyst is different from that of Preparation Example 3.1 in that FeCl3·6H2O is replaced by the same molar number of Co(NO3)26H2O, and the rest is the same as Preparation Example 3.1.

[0040] Comparative Preparation Example 1.1 The preparation method of Cu-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 0.3 g / L, and the rest is the same as Preparation Example 1.1.

[0041] Comparative Preparation Example 1.2 The preparation method of Cu-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the concentration of Cu(NO3)2·3H2O solution is 2.0 g / L, and the rest is the same as Preparation Example 1.1.

[0042] Comparative Preparation Example 1.3 The preparation method of Fe-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the Cu(NO3)2·3H2O solution is replaced by Fe(NO3)2·9H2O solution of the same concentration, and the rest is the same as Preparation Example 1.1.

[0043] Comparative Preparation Example 1.4 The preparation method of La-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the Cu(NO3)2·3H2O solution is replaced by LaCl3 solution of the same concentration, and the rest is the same as Preparation Example 1.1.

[0044] Comparative Preparation Example 1.5 The preparation method of Co-NaA zeolite catalyst is different from that of Preparation Example 1.1 in that the Cu(NO3)2·3H2O solution is replaced by Co(NO3)2·6H2O solution of the same concentration, and the rest is the same as Preparation Example 1.1.

[0045] Example 1.1 A method for removing arsenic from nonferrous metal smelting wastewater comprises the following steps: 1. Add a catalyst (Cu-NaA zeolite catalyst prepared in Preparation Example 1.1) and hydrogen peroxide to non-ferrous metal smelting wastewater, wherein the amount of the catalyst added is 6 g / L and the amount of hydrogen peroxide added is 0.05 mol / L, and then react for 10 min at a temperature of 80° C. and a stirring rate of 250 r / min to obtain pretreated wastewater; 2. Add lime to the pretreated sewage, control the amount of lime added to 10g / L, react for 48min at a temperature of 35°C and a stirring rate of 250r / min, filter and remove the residue and then discharge the water.

[0046] Example 1.2 A method for removing arsenic from nonferrous metal smelting wastewater comprises the following steps: 1. Add a catalyst (Cu-NaA zeolite catalyst prepared in Preparation Example 1.2) and hydrogen peroxide to non-ferrous metal smelting wastewater, wherein the amount of the catalyst added is 6 g / L and the amount of hydrogen peroxide added is 0.05 mol / L, and then react for 3 min at a temperature of 20° C. and a stirring rate of 400 r / min to obtain pretreated wastewater; 2. Add lime to the pretreated sewage, control the amount of lime added to 15g / L, react for 55min at a temperature of 25°C and a stirring rate of 400r / min, filter and remove the residue and then discharge the water.

[0047] Example 1.3 A method for removing arsenic from nonferrous metal smelting wastewater comprises the following steps: 1. Add a catalyst (Cu-NaA zeolite catalyst prepared in Preparation Example 1.1) and hydrogen peroxide to non-ferrous metal smelting wastewater, wherein the amount of the catalyst added is 6 g / L and the amount of hydrogen peroxide added is 0.05 mol / L, and then react for 5 min at a temperature of 60° C. and a stirring rate of 250 r / min to obtain pretreated wastewater; 2. Add lime to the pretreated sewage, control the amount of lime added to 10g / L, react for 48min at a temperature of 30°C and a stirring rate of 300r / min, filter and remove the residue and then discharge the water.

[0048] Examples 2.1-2.3 A method for removing arsenic from non-ferrous metal smelting wastewater, which differs from Example 1.3 in that: in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is replaced by the Cu-NaA zeolite catalyst prepared in Preparation Examples 2.1-2.3, respectively, and the rest is the same as Preparation Example 1.3.

[0049] Example 3.1 A method for removing arsenic from nonferrous metal smelting wastewater, which differs from Example 1.3 in that: in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is replaced by the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 and the Fe prepared in Preparation Example 3.1 in a weight ratio of 1:3.5. 3+ -montmorillonite carbon catalyst, and the rest are the same as in Preparation Example 1.3.

[0050] Example 3.2 A method for removing arsenic from nonferrous metal smelting wastewater, which differs from Example 1.3 in that: in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is replaced by the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 and the Fe prepared in Preparation Example 3.2 in a weight ratio of 1:4. 3+ -montmorillonite carbon catalyst, and the rest are the same as in Preparation Example 1.3.

[0051] Example 3.3 A method for removing arsenic from nonferrous metal smelting wastewater, which is different from Example 3.1 in that: in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 and the Fe 3+ -montmorillonite carbon catalyst weight ratio is 1:3.75, and the rest is the same as Preparation Example 3.1.

[0052] Examples 4.1-4.4 A method for removing arsenic from nonferrous metal smelting wastewater, which is different from Example 3.3 in that: in step I, the Fe 3+ -montmorillonite carbon catalyst was replaced by Fe prepared in Preparation Examples 4.1-4.4 3+ -montmorillonite carbon catalyst, and the rest are the same as in Preparation Example 3.1.

[0053] Comparative Examples 1.1-1.5 The difference from Example 1.3 is that in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is replaced by the catalysts prepared in Comparative Preparation Examples 1.1-1.5 respectively, and the rest is the same as Preparation Example 3.1.

[0054] Comparative Example 2.1 The difference from Example 1.3 is that step I is removed, specifically: lime is added to the non-ferrous metal smelting wastewater, the amount of lime added is controlled to 50 g / L, the reaction is carried out at a temperature of 50°C and a stirring rate of 300 r / min for 48 minutes, and the filter residue is removed and the water is discharged.

[0055] Comparative Example 2.2 The difference from Example 1.3 is that step I is removed, specifically: lime is added to the non-ferrous metal smelting wastewater, the amount of lime added is controlled to be 10 g / L, the reaction is carried out at a temperature of 30°C and a stirring rate of 300 r / min for 48 minutes, and the filter residue is removed and the water is discharged.

[0056] Comparative Example 3 The difference from Example 1.3 is that in step I, the Cu-NaA zeolite catalyst prepared in Preparation Example 1.1 is completely replaced by ferrous sulfate, and the rest is the same as Example 1.3.

[0057] Performance Testing 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 the present 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.

[0058] Table 1 Performance test table 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 Data Analysis: As can be seen from Table 1, the arsenic removal treatment method of Examples 1.1-1.2 of the present application can remove more than 99.806% of 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 not higher than 0.35 mg / L, which proves that the present application adds hydrogen peroxide to the non-ferrous metal smelting wastewater for Fenton treatment, uses Cu-NaA zeolite catalyst as a catalyst to assist the reaction, and then adds lime to the pretreated wastewater that has undergone the Fenton reaction for neutralization and arsenic removal, which can reduce the arsenic content of non-ferrous metal smelting wastewater with complex components to 0.35 mg / L or less, meeting strict emission standards.

[0059] The difference between Example 1.3 and Example 1.1 is that various treatment process parameters are optimized. The data show that the arsenic removal rate in non-ferrous metal smelting wastewater of Example 1.3 is 99.828%, and the arsenic content in the final effluent is 0.31 mg / L, which proves that the present application further reduces the interference of low-valent metal ions on the subsequent arsenic removal process by strictly controlling the temperature and reaction time in step I and the temperature and stirring speed in step II. The short-term strong oxidation reaction helps to quickly reduce the number of low-valent ions in the system and promote the generation of high-valent ions, making the entire treatment process more stable and controllable. It can not only promote the formation of stable flocculent coagulants with high-valent metal ions and arsenate in the sewage, but also effectively avoid the increase in energy consumption and reaction runaway caused by excessive temperature, improve the contact efficiency between hydroxide ions and high-valent ions in the system, promote the formation and stability of colloids, thereby more effectively combining with arsenate to form flocculent coagulants and precipitate, and finally achieve efficient arsenic removal effect.

[0060] The difference between Example 2.1-2.3 and Example 1.3 is that the Cu-NaA zeolite catalyst is different. The data show that Example 2.3 has the highest arsenic removal rate in non-ferrous metal smelting wastewater and the lowest arsenic content in the final effluent, proving that the present application controls the loading amount of Cu by strictly controlling the concentration of the Cu(NO3)2·3H2O solution. At this time, the catalytic effect and adsorption effect of the Cu-NaA zeolite catalyst can achieve the 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 surface of the NaA zeolite will be greatly reduced, affecting the adsorption effect; if the concentration of the Cu(NO3)2·3H2O solution is too low, its catalytic effect is impaired and the intensity of the pretreatment reaction cannot be significantly promoted.

[0061] The difference between Examples 3.1-3.3 and Example 1.3 is that Fe 3+ -montmorillonite carbon catalyst, the data show that the arsenic removal rate in non-ferrous metal smelting wastewater in Examples 3.1-3.2 is improved, and the arsenic content in the final effluent is reduced, proving that the Fe 3+ -Montmorillonite carbon catalyst and Cu-NaA zeolite catalyst can play a good synergistic effect, because Fe 3+ -Montmorillonite carbon catalyst has excellent adsorption properties and a high specific surface area, which can effectively enrich low-valent metal ions in wastewater, promote their oxidation conversion in the Fenton reaction, and reduce the interference of these low-valent metal ions in the arsenic removal process; at the same time, the introduction of Cu-NaA zeolite catalyst enhances the catalytic activity of the system, accelerates the process of hydrogen peroxide decomposition to generate hydroxyl radicals, and improves the redox capacity of the entire system.

[0062] The difference between Examples 4.1-4.4 and Example 3.3 is that Fe 3+ -montmorillonite carbon catalyst is different, among which Example 4.3 has the highest arsenic removal rate in non-ferrous metal smelting wastewater and the lowest arsenic content in the final effluent, proving that the application strictly controls the weight ratio of montmorillonite to sodium alginate to be 1:2, so that the prepared Fe 3+ -Montmorillonite carbon catalyst has a more uniform structure and a higher active surface area, which enhances the adsorption capacity and catalytic efficiency of the catalyst. This further improves the rate and degree of conversion of low-valent metal ions to high-valent metal ions in the Fenton reaction, reduces the interference of low-valent metal ions on the subsequent arsenic removal process, and adsorbs more arsenic-containing ions in the water body, thereby significantly reducing the arsenic content in the final effluent, achieving the effect of efficient arsenic removal.

[0063] The difference between Comparative Example 1.1-1.2 and Example 1.3 is that when preparing the Cu-NaA zeolite catalyst used in this example, the concentration of the Cu(NO3)2·3H2O solution is different. The data show that the arsenic removal rate in the non-ferrous metal smelting wastewater of Comparative Example 1.1-1.2 is significantly reduced, and the arsenic content in the final effluent is significantly increased, proving that the present application controls the Cu loading by strictly controlling the concentration of the Cu(NO3)2·3H2O solution. At this time, the catalytic effect and adsorption effect of the Cu-NaA zeolite catalyst can achieve 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 surface of the NaA zeolite will be greatly reduced, affecting the adsorption effect; if the concentration of the Cu(NO3)2·3H2O solution is too low, its catalytic effect is impaired, and the intensity of the pretreatment reaction cannot be significantly promoted.

[0064] The difference between Comparative Examples 1.3-1.5 and Example 1.3 is that when preparing the Cu-NaA zeolite catalyst used in this example, the Cu(NO3)2·3H2O solution was replaced by Fe(NO3)2·9H2O solution, LaCl3 solution and Co(NO3)2·6H2O solution, respectively. The data showed 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, proving that the Cu-NaA zeolite catalyst of the present application not only has excellent catalytic ability, but also has good adsorption effect. After being put into the water body, it can not only catalyze the Fenton reaction, but also pre-adsorb a part of arsenic before arsenic removal, thereby further improving the arsenic removal effect of the present application.

[0065] The difference between Comparative Example 2.1 and Example 1.3 is that step I is removed, and the process parameters in step II are optimized. The difference between Comparative Example 2.2 and Example 1.3 is that step I is removed. The results show that the arsenic removal rates in non-ferrous metal smelting wastewater in Comparative Example 2.1 and Comparative Example 2.2 are significantly reduced, and the arsenic content in the final effluent is also significantly increased, which proves that the present application adds hydrogen peroxide to the non-ferrous metal smelting wastewater for Fenton treatment, and uses Cu-NaA zeolite catalyst as a catalyst to assist the reaction, which can greatly improve the arsenic removal rate and achieve the effect of efficient arsenic removal.

[0066] The difference between Comparative Example 3 and Example 1.3 is that the Cu-NaA zeolite catalyst is completely replaced with ferrous sulfate. The data show that the arsenic removal rate in non-ferrous metal smelting wastewater in Comparative Example 3 is significantly reduced, and the arsenic content in the final effluent is significantly increased, proving that the Cu-NaA zeolite catalyst of the present application not only has excellent catalytic ability, but also has a good adsorption effect. After being put into the water body, it can not only catalyze the Fenton reaction, but also pre-adsorb a portion of arsenic before arsenic removal, thereby further improving the arsenic removal effect of the present application.

[0067] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for removing arsenic from non-ferrous metal smelting wastewater, characterized in that: The following steps are involved: A catalyst and hydrogen peroxide are added to non-ferrous metal smelting wastewater, and then reacted for 3-10 minutes at a temperature of 20-80° C. and a stirring rate of 250-400 r / min to obtain pretreated wastewater, wherein the catalyst includes a Cu-NaA zeolite catalyst, which is prepared by the following method: The coal gangue is roasted to remove carbon, and after cooling, silicon dioxide is added to continue roasting, and sodium hydroxide solution is added to blend, the temperature is lowered and stirred, vacuum dried, the temperature is increased to crystallize, filtered, washed with water, and dried to obtain NaA zeolite, which is added to a Cu(NO3)2∙3H2O solution with a concentration of 0.5-1.5 g / L, aged, ultrasonicated, crystallized, filtered, washed, dried, and ground to obtain a Cu-NaA zeolite catalyst; Add lime to the pretreated sewage, react for 48-55 minutes at a temperature of 25-35° C. and a stirring rate of 250-400 r / min, filter and remove the residue to obtain water, and the amount of lime added is 10-15 g / L.

2. The method for removing arsenic from 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 removing arsenic from non-ferrous metal smelting wastewater according to claim 1, characterized in that: In the step I, the catalyst further comprises 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 without oxygen, and ground to obtain montmorillonite charcoal, which was then mixed with FeCl3·6H2O for reaction, and the solid was collected by filtration to obtain Fe 3+ -Montmorillonite carbon catalyst.

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

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

75.

6. The method for removing arsenic from non-ferrous metal smelting wastewater according to claim 3, characterized in that: The weight ratio of the montmorillonite to the sodium alginate is 1:

2.

7. The method for removing arsenic from non-ferrous metal smelting wastewater according to claim 1, characterized in that: In the step I, the temperature is 60°C.

8. The method for removing arsenic from non-ferrous metal smelting wastewater according to claim 1, characterized in that: In the step I, the reaction was carried out for 5 min.

9. The method for removing arsenic from non-ferrous metal smelting wastewater according to claim 1, characterized in that: In the step II, the temperature is 30°C.

10. The method for removing arsenic from non-ferrous metal smelting wastewater according to claim 1, characterized in that: In step II, the stirring rate is 300 r / min.