A process for purifying wastewater from grinding mills

Abstract

This application discloses a wastewater purification process for grinding mills, belonging to the field of wastewater treatment technology. The process includes the following steps: (1) placing the wastewater in a first sedimentation tank for settling, and then adding the liquid above the sedimentation tank to an equalization tank for homogenization to obtain a first treated liquid; (2) filtering the first treated liquid through a nanofiber filter, and then pumping it into an adsorption column with adsorption resin for adsorption to obtain a second treated liquid; (3) placing the second treated liquid in a second sedimentation tank, adding modified core-shell material for adsorption treatment, and filtering to obtain a third treated liquid; (4) treating the third treated liquid with a nanofiltration membrane to obtain purified wastewater. This process adopts a six-stage treatment method of sedimentation, homogenization, nanofiber filtration, adsorption resin adsorption, modified core-shell material adsorption, and nanofiltration membrane, which can achieve deep purification of wastewater, improve the surface finish of steel billets, and realize the recycling of wastewater.

Description

Technical Field

[0001] This application relates to a process for purifying and treating wastewater from grinding mills, belonging to the field of wastewater treatment technology. Background Technology

[0002] In the precision gravure printing plate production process, the grinding machine is a key piece of equipment for processing the printing rollers. The grinding process continuously generates a large amount of production wastewater, which is mixed with a large amount of iron sludge, copper sludge, metal shavings, and fine solid impurities. Currently, the industry's conventional treatment methods are relatively simple, and grinding wastewater containing iron sludge and copper sludge is difficult to effectively purify and recycle. Wastewater treatment is difficult, and the solid waste separation effect is poor. It can only be directly discharged or frequently replaced, which not only causes serious waste of water resources, but also increases the cost of production sewage discharge and the pressure on environmental protection.

[0003] Currently, when grinding wastewater that has not undergone deep purification is recycled for a long period, hard solid particles such as iron filings and copper sludge remaining in the water will continue to participate in the grinding process during the spraying and circulation. This can easily cause processing defects such as scratches on the printing roller surface and surface pinholes, leading to a deterioration in the surface roughness of the workpiece and a decrease in the grinding smoothness. This severely restricts the processing accuracy and finished product quality of gravure printing plates, reducing the product yield. At the same time, traditional processes generally rely on manual cleaning of sediment sludge periodically, resulting in low automation, high labor intensity, and poor timeliness of sludge cleaning operations. This makes it difficult to adapt to the continuous and large-scale industrial production rhythm, resulting in low overall production efficiency.

[0004] Patent CN121517072A discloses a method for treating wastewater from grinding machines, primarily addressing the issue of incomplete demulsification of oily substances in the wastewater. However, grinding machines used in precision gravure printing primarily employ water-based grinding coolant and water-based lubricating media for cooling and chip removal, without the introduction of large amounts of machine oil, cutting oil, or emulsified oil. Therefore, the content of mineral oil, emulsified oil, and other oily substances in the raw wastewater from these grinding machines is low and does not fall under the category of wastewater containing high concentrations of oil. The main challenge in treating this type of grinding machine wastewater is not the oil itself, but rather the presence of fine suspended metal particles such as iron sludge and copper sludge, metal dust, and high-solids impurities. Therefore, the treatment method described in this patent is not applicable to the purification of wastewater from precision gravure printing grinding machines.

[0005] Therefore, there is an urgent need for a wastewater purification process for precision gravure printing grinding machines in order to achieve wastewater recycling. Summary of the Invention

[0006] To address the aforementioned issues, a wastewater purification process for grinding mills is provided. This process employs a six-stage treatment method, including sedimentation, homogenization, nanofiber filtration, adsorption resin adsorption, modified core-shell material adsorption, and nanofiltration membrane. This method achieves deep purification of the wastewater, improving the surface finish of the steel billet and enabling the recycling of the wastewater.

[0007] This application provides a process for purifying and treating wastewater from grinding mills, including the following steps: (1) Place the wastewater in the first sedimentation tank and let it stand for at least 3 hours. Then filter the liquid above the sedimentation tank and add it to the equalization tank to adjust the pH to 5-6 for homogenization to obtain the first treated liquid. (2) The first treatment liquid is filtered through a nano carbon fiber filter and then pumped into an adsorption column with adsorption resin for adsorption to obtain the second treatment liquid. (3) The second treatment solution is placed in the second sedimentation tank, and the modified core-shell material is added for adsorption treatment. The solution is then filtered to obtain the third treatment solution. The method for preparing the modified core-shell material is as follows: S1: Pretreated zeolite is obtained by calcining and soaking zeolite. S2: Pretreated zeolite was oxidized with potassium permanganate and nitric acid to obtain carboxylated zeolite; S3: Carboxylated zeolite is placed in a solution of diepoxy monomers, and epoxide zeolite is obtained after the reaction. S4: Add epoxide zeolite to the β molecular sieve precursor solution, react at 60-80℃ for 4-8 hours, and obtain the core-shell material after crystallization, drying and calcination; S5: Place the core-shell material in a chitosan solution, where the mass of chitosan accounts for 3-5 wt% of the mass of the core-shell material. Add a pH adjuster dropwise while stirring to adjust the pH to not less than 6. React for more than 8 hours, then filter and wash to obtain the modified core-shell material. (4) The third treatment liquid is treated with nanofiltration membrane to obtain purified wastewater.

[0008] The wastewater purification process described in this application employs multi-stage purification, enabling the dry and wet separation of iron and copper sludge in the wastewater. Furthermore, metal ions can be permanently fixed and stored in the adsorbent, allowing for long-term wastewater treatment and reducing production losses and labor costs. This process also features mild operating conditions and strong automation adaptability, allowing for long-term stable treatment of grinding mill wastewater and facilitating industrial-scale application.

[0009] Current adsorbents mostly use a single material for adsorption. However, single materials have problems such as disordered pores, abrupt changes in pore size, and easy clogging. Therefore, adsorbents made of single materials are difficult to adsorb wastewater for a long time and need to be replaced after a period of use, which increases losses.

[0010] The modified core-shell material used in the wastewater purification process of this application involves the in-situ growth of a β-molecular sieve shell on a carboxylated zeolite core, forming a core-shell composite structure. The epoxide monomer acts as a bridging transition, enabling the formation of a uniformly transitional, gradient-connected multi-level pore structure between the zeolite core and the β-molecular sieve shell. This significantly increases the specific surface area of ​​the core-shell material, thereby increasing the number of adsorption active sites on the surface of the core-shell material. This allows for the stable chelation and storage of copper and iron metal ions, enabling long-term continuous adsorption of wastewater and reducing losses.

[0011] Furthermore, the uniformly transitioned pores and increased specific surface area provide smooth channels for the diffusion and transport of metal ions, thereby increasing the adsorption reaction rate. Spatial confinement also enables stable storage of copper and iron ions, effectively suppressing metal ion desorption and significantly delaying the adsorbent saturation cycle, thus enabling the material to perform long-term continuous adsorption. It also facilitates the loading of chitosan; the modified material surface is enriched with a large number of strong chelating functional groups such as amino, hydroxyl, and carboxyl groups, which further enhance the adsorption of copper and iron ions through chitosan, thereby further improving the purification effect on wastewater.

[0012] Optionally, the mass concentration of the diepoxy monomer in the diepoxy monomer solution is 2-5 wt%.

[0013] The aforementioned mass concentration of the diepoxy monomer ensures uniform grafting of the diepoxy monomer onto the surface of the carboxylated zeolite, resulting in a moderate amount of epoxy groups. This is beneficial for the uniform coating of β-molecular sieves onto the zeolite core, while also preventing excessive epoxy groups from clogging the initial pores on the zeolite surface and affecting the formation of a uniform transition structure of the core-shell material pores.

[0014] Optionally, the diepoxy monomer includes ethylene glycol diglycidyl ether (CAS: 2224-15-9), 1,4-butanediol diglycidyl ether (CAS: 2425-79-8), and 1,6-hexanediol diglycidyl ether (CAS: 16096-31-4).

[0015] The aforementioned diepoxy monomers selected in this application have good solubility and high reactivity with carboxylated zeolite, which can ensure the stable grafting of diepoxy monomers. Furthermore, their molecular chain length is moderate, which can better serve as a bridging medium between zeolite and β molecular sieve, so that the channels in the core-shell material form a uniformly transitioned hierarchical structure, thereby improving the adsorption effect on metal ions in wastewater.

[0016] Optionally, the diepoxy monomer is selected from ethylene glycol diglycidyl ether and 1,6-hexanediol diglycidyl ether in a molar ratio of 1:1.

[0017] The combination of the two substances can optimize the grafting efficiency and bridging effect of epoxy groups, improve the pore connectivity between the core and shell of the core-shell material, facilitate the loading of chitosan, and enhance the storage capacity for metal ions such as iron and copper.

[0018] Optionally, the reaction temperature in step S3 is 40-60℃, and the reaction time is 3-5h.

[0019] The reaction temperature and time ensure uniform and stable grafting of epoxy groups, reduce reaction costs, and facilitate industrial application.

[0020] Optionally, the β-zeolite precursor solution in step S4 includes a silicon source, an aluminum source, a template agent, and water in a molar ratio of 1:(0.1-0.3):(0.5-0.7):(50-70).

[0021] The β-zeolite precursor solution of this application can ensure that a shell layer with moderate thickness and uniform and regular pores grows uniformly on the surface of epoxide zeolite, thereby ensuring a uniform transition of the core-shell material pores, which can improve both the adsorption of metal ions and the storage of metal ions.

[0022] Optionally, the β-zeolite precursor solution in S4 includes a silicon source, an aluminum source, a template agent, and water in a molar ratio of 1:0.2:0.6:60.

[0023] The shell prepared by the above-mentioned β-zeolite precursor solution has the best mechanical properties and can maintain the pore structure for a long time during use, further improving the service life of the modified core-shell material.

[0024] Specifically, in the above molar ratio, the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the template agent is tetraethylammonium bromide.

[0025] The modified core-shell material prepared in this application can efficiently adsorb metal ions and minute impurities in wastewater within a service life of less than 200 hours. However, after 200 hours, the core and shell layers delaminate, leading to partial release of adsorbed metal ions and minute impurities. Therefore, a new batch of modified core-shell material needs to be used. However, this partial release is not caused by the pore structure of the modified core-shell material. Solving the delamination problem between the core and shell layers would greatly improve the service life of the modified core-shell material. To solve this problem, this application also makes the following improvements: The β-zeolite precursor solution also contains 3-10 wt% polymer, which is obtained by polymerizing N-methylallylamine and p-acetoxystyrene in a molar ratio of 1:(0.1-0.3).

[0026] The polymers contained in the β-zeolite precursor solution have three main functions: First, they can anchor the amino groups in N-methylallylamine to the epoxy groups on the zeolite surface, promoting uniform coating of the β-zeolite shell onto the zeolite core, improving the bonding force between the core and shell layers, and reducing core-shell delamination. Second, if all polymers are obtained by polymerizing N-methylallylamine, the reaction sites of the polymers will be too dense, leading to local agglomeration and growth on the surface of the epoxide zeolite, resulting in pore blockage. By using acetoxystyrene to regulate the position of N-methylallylamine in the polymer, it is ensured that N-methylallylamine reacts fully with the epoxy groups on the surface of the epoxide zeolite, avoiding local pore blockage and improving pore uniformity. Third, acetoxystyrene can stabilize the core-shell bridging effect, enhancing the rigidity and thermal stability of the β-zeolite, preventing the decomposition and collapse of the pores during the crystallization and calcination of the zeolite, and further inhibiting core-shell delamination.

[0027] Modified core-shell materials prepared from polymer-containing β-zeolite precursor solutions have a service life that can be extended to more than 400 hours compared to modified core-shell materials without added polymers, significantly improving the service life of modified core-shell materials.

[0028] The polymer prepared by the above molar ratio can be dissolved in the β-zeolite precursor solution. If the amount of p-acetoxystyrene is too large, it cannot be dissolved in the β-zeolite precursor solution, and thus the above effect cannot be achieved. Therefore, the molar ratio of p-acetoxystyrene in this application cannot exceed the above range.

[0029] Optionally, the mass ratio of the modified core-shell material to the volume ratio of the second treatment liquid is (0.2-1):1, in g / L.

[0030] The above mass-to-volume ratio ensures that the modified core-shell material fully adsorbs copper and iron ions and fine impurities in the wastewater, while avoiding resource waste caused by excessive use of modified core-shell material. This optimizes adsorption efficiency and helps achieve stable storage of copper and iron ions in the modified core-shell material.

[0031] Optionally, the temperature of the adsorption column adsorption treatment in step (2) is 20-25℃ and the time is 15-30min.

[0032] The adsorption resin used in this application is CR resin. Under the above-mentioned temperature and time, the adsorption resin can efficiently adsorb trace organic matter and impurity ions in wastewater, avoid interfering with the adsorption effect of subsequent modified core-shell materials, and improve the treatment efficiency of wastewater.

[0033] Optionally, the temperature for the adsorption treatment of the modified core-shell material in step (3) is 30-40℃ and the time is 1-1.5h.

[0034] The adsorption temperature of modified core-shell materials is higher than that of adsorption resins. At this temperature, the adsorption activity of the modified core-shell materials can be improved, enhancing the complexation and chelation effect on metal ions. Furthermore, it can prevent the desorption of metal ions, achieving stable storage of metal ions. The aforementioned adsorption time ensures effective adsorption of metal ions in wastewater, reducing the metal ion content in the third-stage treatment solution, shortening the treatment time, and improving treatment efficiency.

[0035] The beneficial effects of this application include, but are not limited to: 1. According to the wastewater purification process of the grinding mill in this application, the wastewater can be automatically purified and the dry mud can be automatically collected and packaged during the operation of the grinding mill. This not only improves the smoothness of the steel billet after grinding and reduces the problem of roughness of the steel billet caused by scratches and pinholes caused by iron filings and copper mud contained in the water, but also allows the purified wastewater to be reused, reducing resource waste.

[0036] 2. According to the grinding mill wastewater purification process of this application, an adsorption resin is used for the initial adsorption of copper and iron impurities, followed by a secondary adsorption using a composite adsorbent of amino-modified bentonite and modified core-shell material. This process can significantly reduce the content of copper and iron ions in the wastewater and avoid the desorption of metal ions, making it suitable for the batch treatment of grinding mill wastewater.

[0037] 3. According to the grinding mill wastewater purification process of this application, the core and shell material is provided with through-hole channels and a reasonable pore size gradient distribution, which can significantly increase the adsorption sites of metal ions and stably store metal ions, realize long-term continuous adsorption, and extend the service life of the adsorbent.

[0038] 4. According to the grinding mill wastewater purification process of this application, the wastewater is subjected to multi-stage treatment including sedimentation, resin adsorption, adsorbent adsorption, and nanofiltration membrane nanofiltration. This process can simultaneously remove various pollutants such as large-particle iron and copper mud, fine suspended impurities, free iron ions, and copper ions from the wastewater, thereby effectively improving the surface finish and overall processing precision of the grinding roller and increasing the product yield. Attached Figure Description

[0039] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a process flow diagram of the grinding mill wastewater purification treatment involved in this application. Detailed Implementation

[0040] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0041] Unless otherwise specified, all raw materials used in the embodiments and comparative examples of this application were purchased commercially. The adsorption resin used in the following embodiments and comparative examples is Mitsubishi Chemical's CR11 series adsorption resin, the nanofiber filter screen has a mesh size of 200 mesh, the nanofiltration membrane has a molecular weight cutoff of 400 Da, and the zeolite particle size is 0.5 mm. In the β-molecular sieve precursor solution, the aluminum source is boehmite (calculated as Al2O3 molar ratio), the silicon source is tetraethyl orthosilicate (calculated as SiO2), and the template agent is tetraethylammonium bromide.

[0042] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art. The polymers of Examples 8-10 of this application can dissolve in the β-zeolite precursor solution, while the polymer in Example 11 is dispersed in the β-zeolite precursor solution and cannot be completely dissolved in it.

[0043] The flowcharts for the wastewater purification treatment process of grinding mills in the following embodiments and comparative examples are provided. Figure 1 .

[0044] Example 1 This embodiment relates to a process for purifying and treating wastewater from a grinding mill, including the following steps: (1) The wastewater discharged from the grinding mill was placed in the first sedimentation tank and left to stand for 3 hours. Then, the liquid above the sedimentation tank was filtered through a 10-mesh screen and added to the adjustment tank. The pH was adjusted to 6 with dilute sulfuric acid and homogenized at a stirring rate of 80 r / min to obtain the first treated liquid. (2) The first treatment liquid is filtered through a nano carbon fiber filter, and then pumped into an adsorption column with adsorption resin for adsorption at 25°C for 15 min to obtain the second treatment liquid. (3) The second treatment solution is placed in the second sedimentation tank, and the modified core-shell material is added for adsorption treatment at 30°C for 1.5 h. The mass ratio of the modified core-shell material to the volume of the second treatment solution is 1:1, and the unit is g / L. The third treatment solution is obtained by filtration through a 300-mesh sieve. The preparation method of the modified core-shell material is as follows: S1: The zeolite was calcined at 400℃ for 120 min, then soaked in 10wt% sodium chloride aqueous solution for 24 h, filtered and dried to obtain pretreated zeolite; S2: Pretreated zeolite and potassium permanganate were stirred to form a mixture. Then, nitric acid solution was added to the mixture and stirred to form a paste. The mixture was then reacted at 80°C for 120 min. The reactants were then washed with water until the wash water no longer showed a distinct purple-red color. The mixture was filtered and dried to obtain carboxylated zeolite. The mass ratio of pretreated zeolite, potassium permanganate, and nitric acid solution was 1:0.15:0.3, and the mass concentration of the nitric acid solution was 15 wt%. S3: Carboxylated zeolite was placed in a 2 wt% solution of 1,4-butanediol diglycidyl ether, and 2 wt% of triethylbenzylammonium bromide was added as a catalyst. The reaction was carried out at 80°C for 5 h. After filtration, washing with water and drying, epoxidized zeolite was obtained. S4: Mix silicon source, aluminum source, template agent and water in a molar ratio of 1:0.1:0.5:50 and stir at 80 r / min for 30 min to obtain β molecular sieve precursor solution; Epoxy zeolite was added to a β molecular sieve precursor solution and reacted at 80°C for 4 hours. Then, it was crystallized at 120°C for 48 hours, dried, and calcined at 500°C for 4 hours to obtain the core-shell material. S5: The core-shell material is placed in a 1wt% chitosan acetic acid solution, where the mass of chitosan accounts for 5wt% of the mass of the core-shell material. Sodium carbonate is added dropwise at a speed of 100r / min to adjust the pH to 6. After reacting for 8 hours, the mixture is filtered, washed with water until neutral, and dried to obtain the modified core-shell material. (4) The third treatment liquid is treated by nanofiltration membrane to obtain purified wastewater, which is then used in the grinding mill.

[0045] Example 2 This embodiment relates to a process for purifying and treating wastewater from a grinding mill, including the following steps: (1) The wastewater discharged from the grinding mill was placed in the first sedimentation tank and left to stand for 5 hours. Then, the liquid above the sedimentation tank was filtered through a 10-mesh screen and added to the adjustment tank. The pH was adjusted to 5 with dilute sulfuric acid and homogenized at a stirring rate of 80 r / min to obtain the first treatment liquid. (2) The first treatment liquid is filtered through a nano carbon fiber filter and then pumped into an adsorption column with adsorption resin for adsorption at 20°C for 30 min to obtain the second treatment liquid. (3) The second treatment solution is placed in the second sedimentation tank, and the modified core-shell material is added for adsorption treatment at 40°C for 1 hour. The mass ratio of the modified core-shell material to the volume of the second treatment solution is 0.2:1, with units of g / L. The third treatment solution is obtained by filtration through a 300-mesh sieve. The preparation method of the modified core-shell material is as follows: S1: The zeolite was calcined at 400℃ for 120 min, then soaked in 10wt% sodium chloride aqueous solution for 24 h, filtered and dried to obtain pretreated zeolite; S2: Pretreated zeolite and potassium permanganate were stirred to form a mixture. Then, nitric acid solution was added to the mixture and stirred to form a paste. The mixture was then reacted at 80°C for 120 min. The reactants were then washed with water until the wash water no longer showed a distinct purple-red color. The mixture was filtered and dried to obtain carboxylated zeolite. The mass ratio of pretreated zeolite, potassium permanganate, and nitric acid solution was 1:0.15:0.3, and the mass concentration of the nitric acid solution was 15 wt%. S3: Carboxylated zeolite was placed in a 5 wt% ethylene glycol diglycidyl ether solution, and 2 wt% triethylbenzylammonium bromide was added as a catalyst. The reaction was carried out at 90°C for 3 h. After filtration, washing with water and drying, epoxidized zeolite was obtained. S4: Mix silicon source, aluminum source, template agent and water in a molar ratio of 1:0.3:0.7:70 and stir at 80 r / min for 30 min to obtain β molecular sieve precursor solution; Epoxy zeolite was added to a β molecular sieve precursor solution and reacted at 60°C for 8 hours. Then, it was crystallized at 120°C for 48 hours, dried, and calcined at 500°C for 4 hours to obtain the core-shell material. S5: The core-shell material is placed in a 1wt% chitosan acetic acid solution, where the mass of chitosan accounts for 3wt% of the mass of the core-shell material. Sodium carbonate is added dropwise at a speed of 100r / min to adjust the pH to 6. After reacting for 8 hours, the mixture is filtered, washed with water until neutral, and dried to obtain the modified core-shell material. (4) The third treatment liquid is treated by nanofiltration membrane to obtain purified wastewater, which is then used in the grinding mill.

[0046] Example 3 This embodiment relates to a process for purifying and treating wastewater from a grinding mill, including the following steps: (1) The wastewater discharged from the grinding mill was placed in the first sedimentation tank and left to stand for 4 hours. Then, the liquid above the sedimentation tank was filtered through a 10-mesh screen and added to the adjustment tank. The pH was adjusted to 6 with dilute sulfuric acid and homogenized at a stirring rate of 80 r / min to obtain the first treated liquid. (2) The first treatment liquid is filtered through a nano carbon fiber filter, and then pumped into an adsorption column with adsorption resin for adsorption at 25°C for 20 min to obtain the second treatment liquid. (3) The second treatment solution is placed in the second sedimentation tank, and the modified core-shell material is added for adsorption treatment at 35°C for 1.5 h. The mass ratio of the modified core-shell material to the volume of the second treatment solution is 0.8:1, in g / L. The third treatment solution is obtained by filtration through a 300-mesh sieve. The preparation method of the modified core-shell material is as follows: S1: The zeolite was calcined at 400℃ for 120 min, then soaked in 10wt% sodium chloride aqueous solution for 24 h, filtered and dried to obtain pretreated zeolite; S2: Pretreated zeolite and potassium permanganate were stirred to form a mixture. Then, nitric acid solution was added to the mixture and stirred to form a paste. The mixture was then reacted at 80°C for 120 min. The reactants were then washed with water until the wash water no longer showed a distinct purple-red color. The mixture was filtered and dried to obtain carboxylated zeolite. The mass ratio of pretreated zeolite, potassium permanganate, and nitric acid solution was 1:0.15:0.3, and the mass concentration of the nitric acid solution was 15 wt%. S3: Carboxylated zeolite was placed in a 4 wt% solution of diepoxy monomers, and 2 wt% of triethylbenzylammonium bromide was added as a catalyst. The reaction was carried out at 80°C for 4 h. After filtration, washing with water and drying, epoxide zeolite was obtained. The diepoxy monomers were selected from ethylene glycol diglycidyl ether and 1,6-hexanediol diglycidyl ether in a molar ratio of 1:1. S4: Mix silicon source, aluminum source, template agent and water in a molar ratio of 1:0.2:0.6:60 and stir at 80 r / min for 30 min to obtain β molecular sieve precursor solution; Epoxy zeolite was added to a β molecular sieve precursor solution and reacted at 70°C for 6 hours. Then, it was crystallized at 120°C for 48 hours, dried, and calcined at 500°C for 4 hours to obtain the core-shell material. S5: The core-shell material is placed in a 1wt% chitosan acetic acid solution, where the mass of chitosan accounts for 4wt% of the mass of the core-shell material. Sodium carbonate is added dropwise at a speed of 100r / min to adjust the pH to 7. After reacting for 8 hours, the mixture is filtered, washed with water until neutral, and dried to obtain the modified core-shell material. (4) The third treatment liquid is treated by nanofiltration membrane to obtain purified wastewater, which is then used in the grinding mill.

[0047] Example 4 The difference between this embodiment and Embodiment 3 is that the mass concentration of the diepoxy monomer solution is 8 wt%, while the rest is the same as in Embodiment 3.

[0048] Example 5 The difference between this embodiment and Embodiment 3 is that all the diepoxy monomers are ethylene glycol diglycidyl ether, while the rest are the same as in Embodiment 3.

[0049] Example 6 The difference between this embodiment and Example 3 is that the molar ratio of ethylene glycol diglycidyl ether and 1,6-hexanediol diglycidyl ether in the diepoxy monomer is 1:3, while the rest is the same as in Example 3.

[0050] Example 7 The difference between this embodiment and embodiment 3 is that the mass ratio of the modified core-shell material to the volume of the second treatment liquid is 0.1:1, while the rest is the same as in embodiment 3.

[0051] Example 8 The difference between this embodiment and Example 3 is that the β-zeolite precursor solution also contains 3 wt% polymer of the total mass of the β-zeolite precursor solution. The polymer is prepared by adding N-methylallylamine and p-acetoxystyrene in a molar ratio of 1:0.3 to a solvent (the volume ratio of water and DMSO is 1:1), followed by adding 2 wt% azobisisobutyronitrile as an initiator, polymerizing at 60°C for 6 hours, and then distilling under reduced pressure, washing with solvent, and distilling under reduced pressure to obtain a liquid polymer. The rest is the same as in Example 3.

[0052] Example 9 The difference between this embodiment and Example 3 is that the β-zeolite precursor solution also contains 10 wt% polymer of the total mass of the β-zeolite precursor solution. The polymer is prepared by adding N-methylallylamine and p-acetoxystyrene in a molar ratio of 1:0.1 to a solvent (the volume ratio of water and DMSO is 1:1), followed by adding 2 wt% azobisisobutyronitrile as an initiator, polymerizing at 60°C for 6 hours, and then distilling under reduced pressure, washing with solvent, and distilling under reduced pressure to obtain a liquid polymer. The rest is the same as in Example 3.

[0053] Example 10 The difference between this embodiment and Example 9 is that the molar ratio of N-methylallylamine to p-acetoxystyrene in the polymer is 1:0.5, while the rest is the same as in Example 9.

[0054] Example 11 The difference between this embodiment and Example 9 is that no p-acetoxystyrene is added to the polymer; otherwise, they are the same as in Example 9.

[0055] Comparative Example 1 The difference between this comparative example and Example 3 is that step (2) was not performed; otherwise, it is the same as Example 3.

[0056] Comparative Example 2 The difference between this comparative example and Example 3 is that step (3) does not include steps S3-S4, which involves modifying the carboxylated zeolite in a chitosan solution. The rest is the same as in Example 3.

[0057] Comparative Example 3 The difference between this comparative example and Example 3 is that epichlorohydrin is used instead of the diepoxy monomer; otherwise, they are the same as in Example 3.

[0058] Test Example 1 Using the methods described in the above embodiments and comparative examples, the wastewater from the grinding mill was purified. The total content of ferrous and ferric ions in the wastewater was 145.37 mg / L, and the content of ferrous ions was 126.85 mg / L. The iron and copper ion content of the purified wastewater was tested, and the iron ion removal rate and copper ion removal rate were calculated. The test results are shown in Table 1. In Table 1, the higher the iron ion removal rate and copper ion removal rate, the better the wastewater purification effect.

[0059] Wherein, the iron ion removal rate = [(C1-C2 / C1)]×100%, the copper ion removal rate = [(C3-C4 / C4)]×100%, C1 is the total content of ferrous and ferric ions in the initial wastewater, in mg / L; C2 is the total content of ferrous and ferric ions in the purified wastewater, in mg / L; C3 is the copper ion content in the initial wastewater, in mg / L; and C4 is the copper ion content in the purified wastewater, in mg / L.

[0060] Table 1

[0061] Test Example 2 Using the methods described in the above embodiments and comparative examples, continuous purification treatment of grinding mill wastewater was carried out in the manner of Test Example 1. That is, the modified core-shell material used to treat one round of wastewater was reused to treat the next round of wastewater without replacement of the modified core-shell material. However, the other components, such as the nanofiber filter, adsorption resin, and nanofiltration membrane, were replaced. Using the treatment time of the modified core-shell material as a node, the iron and copper ion contents of the wastewater after 200 hours and 400 hours of purification were tested, and the decrease rates of iron and copper ion removal were calculated. The test results are shown in Table 2. Simultaneously, a force of 20N was applied to the modified core-shell material after 200 hours and 400 hours of purification to observe whether it broke. In Table 2, the lower the decrease rates of iron and copper ion removal, the better the continuous adsorption effect of the modified core-shell material.

[0062] The iron ion removal rate decrease rate = [(initial iron ion removal rate - iron ion removal rate at a certain time point) / initial iron ion removal rate] × 100%, and the copper ion removal rate decrease rate = [(initial copper ion removal rate - copper ion removal rate at a certain time point) / initial iron ion removal rate] × 100%. The aforementioned "certain time point" refers to the 200h and 400h time points. The calculation methods for iron ion removal rate and copper ion removal rate are the same as in Example 1.

[0063] Table 2

[0064] As can be seen from the data in Tables 1 and 2, the wastewater purification process of this application can efficiently purify the wastewater from the grinding mill and also play a long-term role in extending the service life of the modified core-shell material, thereby reducing wastewater treatment losses.

[0065] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A process for purifying and treating wastewater from a grinding mill, characterized in that, Includes the following steps: (1) Place the wastewater in the first sedimentation tank and let it stand for at least 3 hours. Then filter the liquid above the sedimentation tank and add it to the equalization tank to adjust the pH to 5-6 for homogenization to obtain the first treated liquid. (2) The first treatment liquid is filtered through a nano carbon fiber filter and then pumped into an adsorption column with adsorption resin for adsorption to obtain the second treatment liquid. (3) The second treatment solution is placed in the second sedimentation tank, and the modified core-shell material is added for adsorption treatment. The solution is then filtered to obtain the third treatment solution. The method for preparing the modified core-shell material is as follows: S1: Pretreated zeolite is obtained by calcining and soaking zeolite. S2: Pretreated zeolite was oxidized with potassium permanganate and nitric acid to obtain carboxylated zeolite; S3: Carboxylated zeolite is placed in a solution of diepoxy monomers, and epoxide zeolite is obtained after the reaction. S4: Add epoxide zeolite to the β molecular sieve precursor solution, react at 60-80℃ for 4-8 hours, and obtain the core-shell material after crystallization, drying and calcination; S5: Place the core-shell material in a chitosan solution, where the mass of chitosan accounts for 3-5 wt% of the mass of the core-shell material. Add a pH adjuster dropwise while stirring to adjust the pH to not less than 6. React for more than 8 hours, then filter and wash to obtain the modified core-shell material. (4) The third treatment liquid is treated with nanofiltration membrane to obtain purified wastewater.

2. The wastewater purification process for grinding mills according to claim 1, characterized in that, The mass concentration of the diepoxy monomer in the solution is 2-5 wt%.

3. The wastewater purification process for grinding mills according to claim 2, characterized in that, The diepoxy monomers include ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether.

4. The wastewater purification process for grinding mills according to claim 3, characterized in that, The diepoxy monomer is selected from ethylene glycol diglycidyl ether and 1,6-hexanediol diglycidyl ether in a molar ratio of 1:

1.

5. The wastewater purification process for grinding mills according to claim 4, characterized in that, The reaction temperature in step S3 is 80-90℃, and the reaction time is 3-5h.

6. The wastewater purification process for grinding mills according to claim 1, characterized in that, In step S4, the β-zeolite precursor solution includes a silicon source, an aluminum source, a template agent, and water in a molar ratio of 1:(0.1-0.3):(0.5-0.7):(50-70).

7. The wastewater purification process for grinding mills according to claim 6, characterized in that, In step S4, the β-zeolite precursor solution includes a silicon source, an aluminum source, a template agent, and water in a molar ratio of 1:0.2:0.6:

60.

8. The wastewater purification process for grinding mills according to any one of claims 1-6, characterized in that, The mass ratio of the modified core-shell material to the volume ratio of the second treatment liquid is (0.2-1):1, with units of g / L.

9. The wastewater purification treatment process for grinding mills according to any one of claims 1-6, characterized in that, The temperature for the adsorption column adsorption treatment in step (2) is 20-25℃, and the time is 15-30 min.

10. The wastewater purification process for grinding mills according to any one of claims 1-6, characterized in that, Step (3) The temperature for the adsorption treatment of the modified core-shell material is 30-40℃ and the time is 1-1.5h.

Images