Multi-section environment-friendly water-based cutting fluid regeneration process

Abstract

This invention provides a multi-stage environmentally friendly water-based cutting fluid regeneration process, belonging to the field of industrial wastewater treatment and recycling technology. This multi-stage environmentally friendly water-based cutting fluid regeneration process includes S1, a gravity sedimentation coarse filtration stage: waste cutting fluid is subjected to long-term gravity sedimentation under specific hydrostatic conditions, specifically for removing heavy, large-particle impurities, providing pretreatment for subsequent precision filtration. By setting up multi-stage progressive and functionally specialized physical purification stages, the process systematically solves the problem of efficiently removing complex pollutants from waste cutting fluid. Compared to traditional single-treatment methods, this process first utilizes gravity sedimentation to specifically target heavy, large particles, then uses a specific mesh filter to selectively trap lightweight abrasives, subsequently uses centrifugal force to efficiently separate fine metal powders, and finally uses a nanofiber membrane to achieve deep removal of submicron-level impurities and colloids.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment and recycling technology, specifically relating to a multi-stage environmentally friendly water-based cutting fluid regeneration process. Background Technology

[0002] Water-based cutting fluids, as an indispensable industrial medium in machining, are widely used in turning, milling, grinding, drilling, and other machining processes, serving functions such as cooling, lubrication, cleaning, and rust prevention. However, during circulation, cutting fluids inevitably introduce various contaminants, mainly including: 1. Solid particles, such as metal chips, metal powders, wear particles from machine tool guideways, and abrasive materials shed from grinding wheels (such as silica sand, silicon carbide, and alumina); 2. Spilled oils, such as leaked oil from machine tool hydraulic systems and guideway oils; 3. Microorganisms, as cutting fluids are rich in nutrients, bacteria and fungi will multiply rapidly under suitable temperatures; 4. Consumption of effective components, as the concentration of effective components such as lubricants, rust inhibitors, and extreme pressure additives in the cutting fluid decreases due to carry-over and consumption.

[0003] Pollution and consumption can lead to a sharp deterioration in the performance of cutting fluid, manifested as foul odor, deterioration, decreased pH value, loss of rust prevention properties, and insufficient lubrication. It may also clog machine tool nozzles and pipelines, ultimately affecting the surface quality and dimensional accuracy of machined workpieces, and even causing machine tool corrosion. The traditional practice is to treat the expired waste cutting fluid as hazardous waste and hand it over to a qualified unit for disposal, and replace it with new fluid. This approach not only generates high costs for waste fluid disposal and new fluid procurement, but also causes a huge waste of resources and a burden on the environment. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-stage environmentally friendly water-based cutting fluid regeneration process, which aims to solve the problems of liquid odor, deterioration, pH decrease, loss of rust prevention performance, and insufficient lubrication in the existing technology. These problems can clog machine tool nozzles and pipelines, ultimately affecting the surface quality and dimensional accuracy of machined workpieces, and even leading to machine tool corrosion. The traditional approach is to treat the expired waste cutting fluid as hazardous waste and hand it over to a qualified unit for disposal and replace it with new fluid. This method not only generates high waste fluid treatment costs and new fluid procurement costs, but also causes huge waste of resources and environmental burden.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A multi-stage environmentally friendly water-based cutting fluid regeneration process includes: S1. Gravity sedimentation coarse filtration section: The waste cutting fluid is subjected to long-term gravity sedimentation under specific hydrostatic pressure conditions. It is left to stand at room temperature for 8-24 hours to remove heavy large particulate impurities. S2, Mesh Filter Separation Section: The supernatant after coarse filtration is passed through a 300-500 mesh filter screen to remove impurity particles and fibers with a particle size greater than 10μm, while retaining lightweight abrasive particles such as silica sand. S3, Centrifugal Force Field Refinement Section: Utilizing the centrifugal force field generated by high-speed centrifugation, with a rotor radius of 30-80 cm, the centrifugal force RCF = 1.118 × 10⁻⁵ × r × n 2 (×g), with a rotation speed of 6000-10000 rpm, to separate and remove metal powder with a density greater than water from the cutting fluid that has passed through the mesh filter; S4, Membrane Deep Purification Section: The centrifuged liquid is filtered through a regenerable nanofiber membrane. The nanofiber membrane has a porosity of 70%-80% and a fiber diameter of 150-300nm. The membrane structure consists of a 150-micron nonwoven fabric support layer and a 50-micron nanofiber functional layer. High porosity: Nanofibers can stack to form a three-dimensional network structure, naturally possessing high porosity (70%-90%), ensuring that cutting fluid can pass through quickly; Mechanical strength: The fibers themselves possess a certain strength, allowing the formed membrane to withstand a certain amount of operating pressure. The membrane thickness consists of a 150-micron nonwoven support layer and a 50-micron nanofiber functional layer, enhancing mechanical strength. S5 Intelligent Component Regeneration Section: Real-time online detection of the concentration of key effective components in the membrane-purified liquid, calculation of additive replenishment based on the detection results, and automatic addition of a special additive composition to restore the cutting fluid performance indicators to the new fluid standard.

[0006] In a preferred embodiment of the present invention, in step S1, the waste cutting fluid is left to stand at room temperature for 8-24 hours.

[0007] As a preferred embodiment of the present invention, in step S5, the algorithm for dynamically calculating the amount of additive replenishment takes into account the initial formula of the cutting fluid, the amount of processing fluid, and the consumption rate of various components detected.

[0008] As a preferred embodiment of the present invention, the process further includes a pre-judgment step: before the waste cutting fluid enters the gravity settling tank, it is first subjected to oil-liquid separation treatment to remove any floating oil or impurities that may be mixed in, so as to protect the subsequent purification unit from oil pollution.

[0009] As a preferred embodiment of the present invention, S5 is provided with a feedback control system. The system uses one or more of turbidity, pH value, rust inhibitor concentration and antibacterial agent concentration as detection indicators, compares the detection data with a preset threshold, and then controls the dosing pump to perform variable compensation dosing of one or more additives.

[0010] As a preferred embodiment of the present invention, S4 uses pulse backflush technology to regenerate the nanofiber membrane online. This backflush operation is automatically triggered according to the change in pressure difference before and after the membrane, without interrupting the main process flow, thus ensuring the continuity and efficiency of the process.

[0011] In a preferred embodiment of the present invention, in step S3, the solid sludge after centrifugal separation is collected and discharged by an automatic sludge discharge device, and the centrifuge adopts a self-cleaning drum structure.

[0012] In a preferred embodiment of the present invention, in step S4, the nanofiber membrane is made of one or more materials selected from polyacrylonitrile, polyvinylidene fluoride or polyethersulfone through an electrospinning process and is composited on a nonwoven support layer.

[0013] As a preferred embodiment of the present invention, the online detection system in S5 includes a near-infrared spectroscopy analysis module or an electrochemical sensor array for real-time quantitative analysis of the concentration of at least two components in the rust inhibitor, lubricant, pH buffer and bactericide.

[0014] As a preferred embodiment of the present invention, in step S5, when the turbidity, conductivity or concentration of microbial metabolites of the regenerated liquid exceeds a set threshold, the system automatically returns this portion of the liquid to the front end of the S2 mesh filter separation section for further processing.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. By setting up multi-stage progressive and functionally specialized physical purification stages, the problem of efficient removal of complex pollutants in waste cutting fluid is systematically solved. Compared with traditional single treatment methods, this process first uses gravity sedimentation to target heavy and large particles, then uses a specific mesh filter to selectively trap light abrasives, then uses centrifugal force field to efficiently separate fine metal powders, and finally uses a nanofiber membrane to achieve deep removal of submicron impurities and colloids.

[0016] 2. A qualitative leap from "purification" to "regeneration" has been achieved. This process goes beyond simple liquid cleaning; it actively restores the core chemical properties of cutting fluid, such as rust prevention, lubrication, and antibacterial properties, by monitoring the concentration of key components online in real time and dynamically calculating and precisely adding specialized additives based on algorithmic models. This not only improves the reuse rate of the regenerated fluid, truly restoring its performance to the standards of new fluid for direct reuse in production, but also avoids errors from human experience and waste of additives through intelligent control, ensuring the stability and reliability of the regenerated quality. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart illustrating the operation of the present invention; Figure 2 This is a diagram illustrating the core technology of this invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1

[0020] Please see Figures 1-2 The present invention provides the following technical solutions: A multi-stage environmentally friendly water-based cutting fluid regeneration process includes: S1. Gravity sedimentation coarse filtration section: The waste cutting fluid is subjected to long-term gravity sedimentation under specific hydrostatic pressure conditions. It is left to stand at room temperature for 8-24 hours to remove heavy large particulate impurities. S2, Mesh Filter Separation Section: The supernatant after coarse filtration is passed through a 300-500 mesh filter screen to remove impurity particles and fibers with a particle size greater than 10μm, while retaining lightweight abrasive particles such as silica sand. S3, Centrifugal Force Field Refinement Section: Utilizing the centrifugal force field generated by high-speed centrifugation, with a rotor radius of 30-80 cm, the centrifugal force RCF = 1.118 × 10⁻⁵ × r × n 2 (×g), with a rotation speed of 6000-10000 rpm, to separate and remove metal powder with a density greater than water from the cutting fluid that has passed through the mesh filter; S4, Membrane Deep Purification Section: The centrifuged liquid is filtered through a regenerable nanofiber membrane. The nanofiber membrane has a porosity of 70%-80% and a fiber diameter of 150-300nm. The membrane structure consists of a 150-micron nonwoven fabric support layer and a 50-micron nanofiber functional layer. High porosity: Nanofibers can stack to form a three-dimensional network structure, naturally possessing high porosity (70%-90%), ensuring that cutting fluid can pass through quickly; Mechanical strength: The fibers themselves possess a certain strength, allowing the formed membrane to withstand a certain amount of operating pressure. The membrane thickness consists of a 150-micron nonwoven support layer and a 50-micron nanofiber functional layer, enhancing mechanical strength. S5 Intelligent Component Regeneration Section: Real-time online detection of the concentration of key effective components in the membrane-purified liquid, calculation of additive replenishment based on the detection results, and automatic addition of a special additive composition to restore the cutting fluid performance indicators to the new fluid standard.

[0021] In a specific embodiment of the invention, after the waste cutting fluid is fed into the settling tank, it is left to stand at room temperature for 8-24 hours. Under specific hydrostatic pressure, heavy iron filings and large particles of sand and gravel gradually settle to the bottom of the tank due to density differences, achieving initial separation. After settling, the supernatant is pumped to the mesh filter section to provide pretreated liquid for subsequent processes. When the supernatant passes through a filter device equipped with a 300-500 mesh coarse filter, impurity particles larger than 10 μm (usually between 25-50 μm) and fibrous materials are specifically retained. This effectively removes lightweight abrasive particles such as silica sand, while preventing damage to the subsequent fine filter due to large particle blockage. After filtration, the liquid enters the centrifuge section. After the mesh-filtered liquid is injected into the centrifuge, under conditions of a rotor radius of 30-80 cm and a rotation speed of 6000-10000 rpm, the centrifugal force is calculated using the formula RCF = 1.118 × 10⁻⁻⁶. 5 ·r·n² calculation; In this way, denser metal powders are efficiently separated and collected in the centrifuge's slag collection chamber under centrifugal force. After centrifugation, the liquid enters the cation exchange process. When the centrifuged liquid flows through a columnar container filled with cation exchange resin, the active groups of the resin undergo a displacement reaction with the metal cations in the liquid. Most of the residual metal ions are adsorbed and removed, significantly reducing the liquid's conductivity and corrosivity. When the exchange is saturated, the resin can be recycled through acid regeneration. When the ion-exchanged liquid passes through the nanofiber membrane module, the membrane functional layer (fiber diameter 150-300nm, porosity 70%-80%) forms a three-dimensional network structure. Submicron-sized colloidal particles and impurities larger than 1µm are non-destructively intercepted, significantly improving the liquid's light transmittance. When the membrane flux decreases, a backwashing device is used to regenerate the membrane function. Its nonwoven fabric supports... The composite structure of the support layer (150µm) and the nanofiber layer (50µm) ensures that the membrane maintains its mechanical integrity under operating pressure. When the purified liquid enters the mixing tank, the online concentration sensor detects the content of key components such as rust inhibitors and lubricants in real time. In this way, the control system dynamically calculates the amount of additives to replenish and drives the dosing unit to accurately add special composite additives. When the component indicators are restored to the standard of new liquid, the regenerated cutting fluid is output and packaged through the outlet valve, realizing the full-process regeneration of waste cutting fluid: the gravity sedimentation section and the mesh filter section constitute a staged pretreatment, the centrifugation section and the cation exchange section are used together to enhance the removal of metal impurities, the membrane purification section ensures the removal of submicron particles, and the intelligent regeneration section achieves accurate component restoration. The final regenerated liquid is clear and free of impurities, with performance comparable to new liquid. Moreover, the process is environmentally friendly and efficient. The nanofiber membrane and resin column can be regenerated and recycled, reducing disposal costs and environmental pollution.

[0022] Please refer to the details. Figures 1-2 In step S1, the waste cutting fluid is left to stand at room temperature for 8-24 hours.

[0023] In this embodiment: after the waste cutting fluid enters the gravity settling tank, the system controls the ambient temperature within the room temperature range (usually 15-30℃). This provides stable fluid dynamic conditions for impurity settling and avoids liquid deterioration caused by high temperature or precipitation caused by low temperature. When the settling time is set between 8-24 hours according to the impurity concentration, metal scraps and gravel can settle sufficiently. At the same time, this duration and temperature conditions synergistically inhibit the exponential growth of microorganisms. In this way, while achieving efficient separation of large particles, the formation of biological sludge is controlled from the source, providing pretreated liquid with controlled microbial content for subsequent processes.

[0024] Please refer to the details. Figures 1-2 In step S5, the algorithm for dynamically calculating the amount of additive replenishment takes into account the initial formula of the cutting fluid, the amount of processing fluid, and the consumption rate of various components detected.

[0025] In this embodiment: after the online concentration sensor collects real-time concentration data of key components such as rust inhibitors and extreme pressure agents in the purified cutting fluid, the control system calls the built-in algorithm model. The algorithm first determines the target concentration benchmark based on the initial formula database, then calculates the total amount of missing components by combining the actual treated fluid volume monitored by the flow meter, and simultaneously introduces the consumption rate coefficients of each component fitted from historical data for dynamic correction. After the system completes the multi-parameter fusion calculation, it generates a supplementary formula that matches the current fluid degradation characteristics. The dosing unit accurately adds the chemicals according to this optimal formula, so that the lubricity, rust prevention, and other indicators of the regenerated fluid are simultaneously restored to the new fluid standard, avoiding performance imbalances caused by excessive or insufficient amounts of a single component.

[0026] Please refer to the details. Figures 1-2 The process also includes a pre-judgment step: before the waste cutting fluid enters the gravity settling tank, it is first subjected to oil-liquid separation treatment to remove any floating oil or impurities that may be mixed in, so as to protect the subsequent purification unit from oil pollution.

[0027] In this embodiment, a pre-judgment and pre-treatment step is set at the beginning of the process: before the waste cutting fluid enters the main regeneration system, it first flows through a dedicated oil separation device. This device can effectively identify and separate any free floating oil or impurities that may be mixed in. After this step, most of the foreign oil contaminants are removed in advance, which greatly reduces the processing load of the subsequent purification units, especially protecting the precision filtration unit from oil contamination, and ensuring the stable operation of the entire process chain and the final regeneration effect.

[0028] Please refer to the details. Figures 1-2The S5 is equipped with a feedback control system. This system uses one or more of the following as detection indicators: turbidity, pH value, rust inhibitor concentration and antibacterial agent concentration. It compares the detection data with a preset threshold and then controls the dosing pump to dosing one or more additives with variable compensation.

[0029] In this embodiment: In segment S5, a multi-parameter feedback control system is established. This system simultaneously monitors multiple key performance indicators online, such as turbidity, pH value between 8.5 and 9.5, and concentration of specific components. It continuously compares the real-time monitoring data with the preset target threshold range within the system. Once one or more indicators deviate from the target range, the control system will respond immediately, independently and precisely adjusting the dosing pump of the corresponding additive for variable compensation dosing. This linkage control based on multi-indicator feedback enables the on-demand and precise replenishment of additives, ensuring the comprehensive balance and stability of the chemical properties of the regenerated liquid.

[0030] Please refer to the details. Figures 1-2 The S4 uses pulse backflush technology to regenerate the nanofiber membrane online. This backflush operation is automatically triggered according to the change in pressure difference before and after the membrane, without interrupting the main process flow, thus ensuring the continuity and efficiency of the process.

[0031] In this embodiment: During the operation of the S4 membrane deep purification section, an automatic monitoring system continuously tracks key parameters characterizing the degree of membrane fouling. When the parameter value reaches the preset trigger condition, a pulse backwash system is automatically activated. This system can generate a high-pressure backwash flow in a very short time to efficiently clean the membrane surface. The entire backwash process is designed to be very fast and automated, without stopping the main process's feeding and output. This ensures the continuous recovery of membrane filtration performance while maintaining the continuity and overall efficiency of the entire regeneration process.

[0032] Please refer to the details. Figures 1-2 In step S3, the solid sludge after centrifugal separation is collected and discharged by an automatic sludge discharge device, and the centrifuge adopts a self-cleaning drum structure.

[0033] In this embodiment, the solid-containing sludge generated after high-speed centrifugation is collected and discharged from the system by an automatic sludge discharge device. Simultaneously, the centrifuge used is equipped with a self-cleaning drum structure, which can automatically remove solid particles adhering to the inner wall during centrifugation or intermittent operation, eliminating the need for manual disassembly and cleaning.

[0034] Please refer to the details. Figures 1-2 In step S4, the nanofiber membrane is made of one or more of the following materials: polyacrylonitrile, polyvinylidene fluoride, or polyethersulfone, through an electrospinning process and is composited onto a nonwoven support layer.

[0035] In this embodiment, the nanofiber membrane is composed of one or more polymeric materials selected from polyacrylonitrile, polyvinylidene fluoride, or polyethersulfone, and is formed by electrospinning. The formed nanofiber layer is then laminated onto a nonwoven fabric support layer to form a multilayer composite membrane structure.

[0036] Please refer to the details. Figures 1-2 The online detection system in S5 includes a near-infrared spectroscopy analysis module or an electrochemical sensor array for real-time quantitative analysis of the concentration of at least two components in the rust inhibitor, lubricant, pH buffer, and bactericide.

[0037] In this embodiment, the online detection system includes a near-infrared spectroscopy analysis module, or an electrochemical sensor array, or both. This system is used for real-time, quantitative analysis of the concentration of various components in the regenerated solution. The analyzed components include at least two of the following: rust inhibitors, lubricants, pH buffers, and bactericides.

[0038] Please refer to the details. Figures 1-2 In step S5, when the turbidity, conductivity, or concentration of microbial metabolites of the regenerated liquid exceeds a set threshold, the system automatically returns this portion of the liquid to the front end of the S2 mesh filter separation section for reprocessing.

[0039] In this embodiment: when the online detection system detects that any one or more of the turbidity, conductivity or concentration of microbial metabolites of the regenerated liquid exceeds the preset threshold, the system automatically exports the portion of liquid that does not meet the index and returns it to the front inlet of the S2 mesh filter separation section to re-enter the filtration process.

[0040] The working principle and usage process of this invention: Waste cutting fluid is first collected and pumped into the system. Before formal treatment, a pre-judgment / degreasing step can be optionally installed to remove floating oil through a centrifugal or membrane degreasing device, providing protection for subsequent processes. The waste liquid enters a large settling tank, where it undergoes long-term gravity settling under controlled temperature and time. The densest metal chips and gravel naturally settle to the bottom under gravity, forming sludge, which is periodically discharged. The clarified liquid at the top overflows or is pumped into the next stage. The supernatant after settling flows through a stainless steel woven mesh of a specific mesh size. This step is specifically designed to trap lightweight, large-particle, and unsettled silica sand and abrasive materials, achieving solid-liquid separation. The filter needs to be cleaned or replaced regularly to maintain efficiency. The filtered liquid enters a high-speed centrifuge. Under the action of strong centrifugal force, metal powder with a density greater than water... The sludge, high in solids, is thrown against the wall and separated, and high-solids sludge is discharged. After this step, the liquid becomes initially clear. The centrifuged liquid is then pumped into a nanofiber membrane filtration system. This precision barrier can thoroughly remove submicron-sized colloids, bacteria, residual grease, etc., which is key to restoring the liquid's transparency. The membrane uses pulse backflush technology for online cleaning and regeneration to ensure continuous operation. The purified liquid flows through an online detection system to monitor key indicators such as concentration and pH value in real time. The data is transmitted to the control system, compared with preset standard values, and a dynamic algorithm calculates the types and quantities of additives that need to be added. The system automatically controls the dosing pump to accurately add the additives and mix them evenly. The final regenerated cutting fluid meets the standards of new fluid in terms of appearance and performance. It is then transported back to the production workshop through pipelines and directly reused in machine tool processing, forming a complete cycle.

[0041] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-stage environmentally friendly water-based cutting fluid regeneration process, characterized in that: include: S1. Gravity sedimentation coarse filtration section: The waste cutting fluid is subjected to long-term gravity sedimentation under specific hydrostatic pressure conditions. It is left to stand at room temperature for 8-24 hours to remove heavy large particulate impurities. S2, Mesh Filter Separation Section: The supernatant after coarse filtration is passed through a 300-500 mesh filter screen to remove impurity particles and fibers with a particle size greater than 10μm, while retaining lightweight abrasive particles such as silica sand. S3, Centrifugal Force Field Removal Section: Utilizing the centrifugal force field generated by high-speed centrifugation, with a rotor radius of 30-80 cm, a centrifugal force RCF = 1.118×10-5 × r × n² (×g), and a rotation speed of 6000-10000 rpm, metal powder with a density greater than water in the cutting fluid that has passed through the mesh filter is separated and removed. S4, Membrane Deep Purification Section: The centrifuged liquid is filtered through a regenerable nanofiber membrane. The nanofiber membrane has a porosity of 70%-80% and a fiber diameter of 150-300nm. The membrane structure consists of a 150-micron nonwoven fabric support layer and a 50-micron nanofiber functional layer. High porosity: Nanofibers can stack to form a three-dimensional network structure, naturally possessing high porosity (70%-90%), ensuring that cutting fluid can pass through quickly; Mechanical strength: The fibers themselves possess a certain strength, allowing the formed membrane to withstand a certain amount of operating pressure. The membrane thickness consists of a 150-micron nonwoven support layer and a 50-micron nanofiber functional layer, enhancing mechanical strength. S5 Intelligent Component Regeneration Section: Real-time online detection of the concentration of key effective components in the membrane-purified liquid, calculation of additive replenishment based on the detection results, and automatic addition of a special additive composition to restore the cutting fluid performance indicators to the new fluid standard.

2. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 1, characterized in that: In step S1, the waste cutting fluid is left to stand at room temperature for 8-24 hours.

3. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 2, characterized in that: In S5, the algorithm for dynamically calculating the amount of additive replenishment takes into account the initial formula of the cutting fluid, the amount of treated fluid, and the consumption rate of various components detected.

4. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 3, characterized in that: The process also includes a pre-judgment step: before the waste cutting fluid enters the gravity settling tank, it is first subjected to oil-liquid separation treatment to remove any floating oil or impurities that may be mixed in, so as to protect the subsequent purification unit from oil pollution.

5. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 4, characterized in that: The S5 is equipped with a feedback control system. This system uses one or more of the following as detection indicators: turbidity, pH value, rust inhibitor concentration, and antibacterial agent concentration. It compares the detection data with a preset threshold and then controls the dosing pump to perform variable compensation dosing of one or more additives.

6. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 5, characterized in that: The S4 uses pulse backflush technology to regenerate the nanofiber membrane online. This backflush operation is automatically triggered according to the change in pressure difference across the membrane, without interrupting the main process flow, thus ensuring the continuity and efficiency of the process.

7. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 6, characterized in that: In step S3, the solid sludge after centrifugal separation is collected and discharged by an automatic sludge discharge device, and the centrifuge adopts a self-cleaning drum structure.

8. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 7, characterized in that: In step S4, the nanofiber membrane is made of one or more materials selected from polyacrylonitrile, polyvinylidene fluoride, or polyethersulfone through an electrospinning process and is composited onto a nonwoven support layer.

9. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 8, characterized in that: The online detection system in S5 includes a near-infrared spectroscopy analysis module or an electrochemical sensor array for real-time quantitative analysis of the concentration of at least two components in rust inhibitors, lubricants, pH buffers, and bactericides.

10. The multi-stage environmentally friendly water-based cutting fluid regeneration process according to claim 9, characterized in that: In step S5, when the turbidity, conductivity, or concentration of microbial metabolites of the regenerated liquid exceeds a set threshold, the system automatically returns this portion of the liquid to the front end of the S2 mesh filter separation section for further processing.

Images