Deep purification and cyclic utilization process for white oil of high-strength polyethylene gel spinning system

Abstract

The invention belongs to the technical field of spinning, particularly relates to a high-strength polyethylene gel spinning system white oil deep purification and cyclic utilization process, and aims to solve the problems of incomplete purification, low cyclic utilization rate, unstable reuse quality, large adsorbent loss and high energy consumption in the prior art, and provides the following scheme: the method comprises the following steps: S1, collecting and pretreating crude white oil; the method comprises the following steps: collecting crude white oil generated in a high-strength polyethylene gel spinning extraction section, centrifugal deoiling and dry tail gas condensation, collecting the crude white oil into a crude white oil storage tank, adding a pretreatment aid into the crude white oil, and realizing deep purification and efficient circulation of the high-strength polyethylene gel spinning waste white oil through cooperation of a five-stage closed-loop process and five sets of customized formulas in a nitrogen protection atmosphere. The adsorption efficiency is improved by more than 35%, the index is close to that of fresh white oil, the cyclic utilization rate of the white oil is more than or equal to 95%, the consumption of each ton of fibers is reduced to below 1kg from 20kg, the hazardous waste output can be greatly reduced by more than 85% by the process, and VOC (volatile organic compounds) can be discharged after reaching the standard.

Description

Technical Field

[0001] This invention relates to the field of spinning technology, and in particular to a process for deep purification and recycling of white oil in a high-strength polyethylene gel spinning system. Background Technology

[0002] High-strength polyethylene (ultra-high molecular weight polyethylene, UHMWPE) fiber is a third-generation high-performance fiber with excellent properties such as high specific strength, low density, impact resistance, corrosion resistance, and low temperature resistance. Its specific strength is more than 10 times that of steel wire, and its density is only 0.97 g / cm³. It is widely used in high-end fields such as aerospace, protective equipment, marine engineering, and medical materials.

[0003] For example, Chinese patent application number 201910244186.8 discloses a pretreatment method for a high-strength polyethylene fiber gel spinning system. This method includes the following steps: Step 1: Placing ultra-high molecular weight polyethylene powder in a vacuum chamber and maintaining the pressure and temperature within the vacuum chamber to remove impurities from the surface of the ultra-high molecular weight polyethylene powder; Step 2: Injecting spinning solvent into the ultra-high molecular weight polyethylene powder within the vacuum chamber, so that the solvent wets the ultra-high molecular weight polyethylene under vacuum conditions. This improves the uniformity of dissolution in the spinning system, shortens the pre-swelling time, and facilitates the disintegration of ultra-high molecular weight polyethylene molecular chains, resulting in ultra-high molecular weight polyethylene fibers with high strength and low coefficient of variation in fineness. This is of great significance for ultra-high molecular weight polyethylene fibers and products in the fields of high strength and high fineness uniformity.

[0004] Gel spinning is currently the mainstream process for preparing UHMWPE fibers. This process uses white oil (75#-100#) as the core solvent / dispersion medium, which plays a key role in dissolving UHMWPE powder, ensuring high stretching ratio, lubricating spinning components, and adjusting the viscosity of spinning solution. Its quality directly determines the mechanical properties, dimensional uniformity, and production stability of the fibers.

[0005] During the gel spinning process, after extraction and centrifugation, the white oil becomes contaminated with a large number of complex impurities, mainly including three categories: First, solid impurities, such as UHMWPE micro powder (particle size ≤10μm), equipment corrosion particles (particle size ≤50μm), bleaching clay / activated carbon powder, gels, etc. These impurities can lead to an increase in fuzzy and broken fibers during spinning, affecting the continuity and strength of the fibers. Second, polar impurities, such as moisture (content ≤0.5%), trace extractants (one or two of dichloromethane and tetrachloroethylene, content ≤500ppm), oxidation products (acids, esters, gums, content ≤0.3%), etc. These impurities can damage the stability of the white oil, accelerate its oxidation and yellowing, and affect the solubility of UHMWPE powder, resulting in a decrease in the uniformity of the spinning solution. Third, coloring substances, such as yellow / brown substances generated by the oxidation of aromatic hydrocarbons and unsaturated hydrocarbons. These substances can cause the white oil to yellow, affecting the appearance quality of the fibers and reducing the reusability of the white oil.

[0006] Directly discharging contaminated waste white oil not only causes serious resource waste but also brings severe environmental pressure. Waste white oil is hazardous waste, and its treatment cost is high. Traditional purification processes such as simple filtration and single adsorption have many technical drawbacks: First, purification is incomplete, only removing large particulate solid impurities and failing to effectively remove trace polar impurities, pigments, and oxidation products, leading to a decline in spinning performance after white oil is reused. Second, the recycling rate of white oil is low, usually below 80%, and a large amount of waste white oil still needs to be disposed of. Third, adsorbent consumption is high; traditional adsorbents have poor targeting and low adsorption efficiency, requiring large amounts to be added, which increases production costs. Fourth, the quality of reuse is unstable; traditional processes lack scientific formulation, and the white oil is prone to oxidation and yellowing after reuse, making it unsuitable for long-term recycling. Fifth, energy consumption is high; traditional distillation processes have high temperatures and high energy consumption, and white oil is easily oxidized at high temperatures, further affecting the quality of reuse.

[0007] In existing technologies, some white oil recovery processes attempt to use a combination of methods such as clay adsorption and distillation, but they lack customized material formulations. The adsorbents have low adsorption efficiency and poor targeting, making it difficult to remove multiple impurities simultaneously. White oil is easily oxidized during distillation, resulting in unstable reuse quality. At the same time, the reuse process does not involve scientific formulation adjustment, which cannot match the preparation requirements of spinning dopes, limiting the number of white oil cycles and the reuse effect. In addition, the existing processes have low waste white oil recovery rates and generate a large amount of hazardous waste, which does not conform to the development trend of green production and cannot meet the needs of large-scale industrial production. Summary of the Invention

[0008] Based on the problems of incomplete purification, low recycling rate, unstable reuse quality, large adsorbent loss and high energy consumption in the background technology, this invention proposes a deep purification and recycling process for white oil in high-strength polyethylene gel spinning system.

[0009] The process for deep purification and recycling of white oil in high-strength polyethylene gel spinning systems proposed in this invention includes the following steps:

[0010] S1: Crude white oil collection and pretreatment. Crude white oil generated from the high-strength polyethylene gel spinning extraction section, centrifugal degreasing, and drying tail gas condensation is collected and deposited into a crude white oil storage tank. Pretreatment aids are added to the crude white oil. Under a nitrogen protective atmosphere, the oil is heated at 60-80℃ for 30-60 minutes to break the emulsion, with the stirring speed controlled at 150-200 r / min, to reduce the viscosity of the white oil and disrupt the oil-in-water / water-in-oil emulsion system. Subsequently, free water is separated by a high-efficiency oil-water separator. The free water is allowed to settle and filtered before being discharged in compliance with standards. Then, the oil is passed through a vacuum flash evaporator at a vacuum degree of -0.08 to -0.09 MPa and a temperature of 65-75℃ to remove dissolved water and low-boiling-point extractant from the white oil. The low-boiling-point extractant is condensed and recovered and recycled for use in the spinning extraction section. Finally, the oil is pre-filtered by a 50-100μm basket filter to remove large particulate mechanical impurities, including UHMWPE micro powder, equipment corrosion particles, and bleaching clay powder, to obtain pretreated white oil.

[0011] S2: Primary composite adsorption purification. Pretreated white oil is introduced into a composite adsorption tank. Under a nitrogen protective atmosphere, the temperature is raised to 80-90℃, and the stirring speed is controlled at 120-150 r / min. Customized composite adsorbent is added at a ratio of 0.8-2.0% of the white oil mass. The mixture is stirred for 1 hour and then kept at 82℃ for adsorption. This allows the composite adsorbent to fully adsorb the colloids, oxidation products, some pigments, and trace polar impurities in the white oil. After adsorption is complete, stirring is stopped, and the mixture is allowed to settle for 12 minutes. Subsequently, the mixture is filtered through a plate and frame filter press at a pressure of 0.4 MPa, a temperature of 81℃, and a filtration rate of 7 m³ / (m²·h). The filtrate is collected, and the filter cake is a mixture of adsorbent and impurities. After harmless treatment, the mixture is disposed of. During the adsorption process, the nitrogen flow rate is 0.011 m³ / h to ensure an oxygen-free environment, prevent white oil oxidation, and avoid adsorbent oxidation and inactivation.

[0012] S3: Secondary chromatography adsorption purification. The filtrate is passed into a chromatography adsorption tower, which is filled with a composite adsorption bed. The composite adsorption bed consists of a silica gel layer, an activated carbon layer, and a molecular sieve layer from top to bottom. Each layer is separated by a quartz sand pad. The flow rate of the white oil is controlled at 1 BV / h, the adsorption temperature is 40℃, and the adsorption pressure is 0.2MPa. Deep adsorption is carried out under a nitrogen protective atmosphere. After adsorption, the white oil is precisely filtered through a series of 10μm→5μm→1μm→0.5μm security filters to remove adsorbent powder and ensure that the white oil is free of mechanical impurities.

[0013] S4: Three-stage vacuum distillation purification. Distillation-modifying additives are added to the finely filtered white oil and stirred for 25 minutes at 100–120 r / min to ensure uniform dispersion. The mixture is then introduced into a vacuum distillation column, with the vacuum level controlled at -0.095 MPa, reboiler temperature at 180–220℃, and top temperature at 120–150℃. The column reboiler heating rate is 3–5℃ / min, and the top reflux ratio is 4:1. High-purity nitrogen (≥99.99%) is introduced for stripping during the distillation process. The flow rate is 0.1–0.2 m³ / h, which enhances the removal of residual VOC extractant and odor. Light components are collected at the top of the column, condensed and recovered. The extractant is recycled for use in the spinning extraction section. Light component impurities are incinerated. Refined white oil is collected at the bottom of the column. After being cooled to 60–70°C by a cooler, the refined white oil is sent to the intermediate storage tank. The distillation column is filled with high-efficiency distillation packing material, which is stainless steel corrugated packing material, model 250Y, added at 17% of the distillation column volume. The distillation yield is ≥98%. Nitrogen protection is used throughout the distillation process.

[0014] S5: Blending and recycling of refined white oil formulations. The collected refined white oil is cooled to 40–50°C and transferred to a refined white oil blending tank. Under a stirring speed of 80–100 r / min, fresh white oil, a stability regulator, and an anti-yellowing agent are added sequentially, and the mixture is stirred for 30–40 minutes to ensure uniform mixing of all components. Subsequently, the white oil indicators are tested: purity ≥99.98%, kinematic viscosity 75–80 mm² / s, color ≤1, light transmittance ≥80%, and inorganic content... After passing inspection for mechanical impurities and odorlessness, the refined white oil is pumped into a storage tank and stored under nitrogen pressure maintained at 0.02–0.03 MPa to prevent oxidation. Finally, the refined white oil is transported to the high-strength polyethylene gel spinning and dissolving section for recycling and dissolving UHMWPE powder, achieving a closed-loop cycle. During the blending process, the nitrogen flow rate is 0.03–0.05 m³ / h to ensure an oxygen-free environment. This process utilizes a five-stage closed-loop process and five customized formulations. This process achieves deep purification and efficient recycling of waste white oil from high-strength polyethylene gel spinning, offering multiple significant benefits and outstanding innovation. It utilizes proprietary pretreatment aids, composite adsorbents, modified silica gel, distillation additives, and a recycling formulation to solve the problems of incomplete purification and unstable recycling associated with traditional processes. Adsorption efficiency is increased by over 35%, resulting in white oil purity ≥99.98%, light transmittance ≥80%, and color ≤1. Moisture and extractant residues are extremely low, with indicators approaching those of fresh white oil. White oil recycling rate is ≥95%, fiber consumption is reduced from 20kg to less than 1kg, extractant recovery rate is ≥98%, adsorbent loss is reduced by 30%, and the process remains stable even after more than 10 cycles. Fiber strength is ≥30cN / dtex, without affecting spinning performance. The process significantly reduces hazardous waste generation by over 85%, achieves VOC emission standards, lowers distillation temperature by 5–10℃, and reduces overall energy consumption by 30%. It is compatible with existing production lines, demonstrating outstanding industrialization and green production value.

[0015] Preferably, in step S1, the pretreatment aid, based on the mass of crude white oil, includes 0.1–0.3% demulsifier SP-169, 0.05–0.15% antioxidant 1010, and the remainder is deionized water; the ratio of pretreatment aid to crude white oil is 1:60; demulsifier SP-169 is a polyoxyethylene-polyoxypropylene block copolymer; antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; during the pretreatment process, the nitrogen flow rate is 0.07 m³ / h; limiting the pretreatment aid ratio and process parameters results in faster demulsification, more thorough oil-water separation, antioxidant inhibiting heating oxidation, efficient removal of water and extractant via vacuum flash evaporation, and pre-filtration removing large particulate impurities, laying a stable foundation for subsequent deep purification and reducing subsequent load.

[0016] Preferably, in step S2, the customized composite adsorbent, by weight, comprises 69 parts activated clay, 15 parts modified activated carbon, 10 parts molecular sieve, 4 parts graphene oxide solution, and 2 parts cationic surfactant; the activated clay is natural bentonite activated at 300–350°C, with a specific surface area ≥200 m² / g and an adsorption capacity ≥150 mg / g; the modified activated carbon, by weight, comprises 8% activated carbon, 1% 3-chloro-2-hydroxypropyltrimethylammonium chloride, 9% tannic acid, 42% 3wt% hydroxylamine hydrochloride solution, and 40% 10wt% sodium hydroxide solution; the molecular sieve is 4A molecular sieve with a particle size of 1–3 mm; the graphene oxide solution concentration is 20 wt%, prepared using the Hummers method, and the graphene oxide sheet thickness is 1 nm; the cationic surfactant is octadecyltrimethylammonium chloride with a purity ≥ 98%; The preparation method of the customized composite adsorbent is as follows: First, activated carbon, oxidant and 3-chloro-2-hydroxypropyltrimethylammonium chloride are mixed and refluxed at 75°C for 2 hours. The oxidant is selected from nitric acid and hydrogen peroxide. The mass ratio of oxidant to activated carbon is 1:2. After reflux, tannic acid is added and ultrasonically dissolved for 70 minutes. The ultrasonic power is 350W and the ultrasonic frequency is 27kHz. Then, hydroxylamine hydrochloride solution and sodium hydroxide solution are added and ultrasonically dispersed for 50 minutes. The pH of the reaction system is adjusted to 7.0-7.5. The mixture is filtered and washed until neutral and dried at 107°C for 2 hours to obtain modified activated carbon. The customized composite adsorbent has a scientific formula. Activated clay, modified activated carbon, molecular sieve, graphene oxide and surfactant work synergistically to greatly improve adsorption capacity and efficiency. It can simultaneously remove colloids, pigments and polar impurities, and the adsorption is more targeted.

[0017] Preferably, in step S2, activated clay, modified activated carbon, and molecular sieve are mixed, and graphene oxide solution and cationic surfactant are added. The mixture is ultrasonically dispersed for 35 minutes at a power of 350W and a frequency of 27kHz. Subsequently, it is calcined at 430℃ for 2 hours at a heating rate of 6℃ / min. After cooling to room temperature, it is pulverized to 90 mesh, sieved, and sealed for storage to obtain the customized composite adsorbent. This process clarifies the adsorbent preparation and addition process, strengthens the structure through ultrasonic dispersion and calcination, ensures precise and controllable adsorption conditions, renders the filter cake harmless, achieves high removal rates of solid impurities and colloids, significantly improves the transmittance of white oil, and reduces adsorbent loss.

[0018] Preferably, in step S3, the silica gel is modified silica gel, with the following formula: 93 parts silica gel, 4 parts γ-aminopropyltriethoxysilane, and 3 parts deionized water. The modified silica gel is prepared by mixing silica gel with γ-aminopropyltriethoxysilane and deionized water, hydrolyzing it at 60-70°C for 2 hours, curing it at 120-150°C for 3 hours after hydrolysis, cooling it to room temperature, pulverizing it to 70 mesh, sieving it, and storing it for later use. The activated carbon layer uses modified activated carbon, and the molecular sieve layer uses 4A molecular sieve. A gradient chromatography adsorption bed and modified silica gel are used to deeply remove pigments, aromatics, and acidic substances. Multi-stage precision filtration ensures the absence of mechanical impurities, and the white oil transmittance is ≥80%, further improving the purification accuracy and ensuring the quality of reuse.

[0019] Preferably, in step S4, the components of the distillation modification additive include antioxidant B225, deodorizing agent, and distillation aid. Antioxidant B225 is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:1. The deodorizing agent is a mixture of vanillin and citral in a mass ratio of 2:1, both with a purity ≥99%. The distillation aid is dibutyl phthalate with a purity ≥99.5%. The distillation additive has antioxidant, deodorizing, and distillation aid functions, reduces distillation temperature, improves separation efficiency, enhances VOC removal with nitrogen stripping, achieves a distillation yield ≥98%, and produces white oil with no odor, higher purity, and no yellowing at high temperatures.

[0020] Preferably, in step S5, the recycled formulation consists of: 95 parts refined white oil, 4 parts fresh white oil, 0.7 parts stability modifier, and 0.3 parts anti-yellowing agent. The fresh white oil is 75# to 100# industrial grade white oil with a purity ≥99.99% and a kinematic viscosity of 75 to 80 mm² / s. The stability modifier is a mixture of calcium stearate and zinc stearate at a mass ratio of 3:2, both with a purity ≥98%. The anti-yellowing agent is a mixture of triphenyl phosphite and UV-531 at a mass ratio of 4:1, with triphenyl phosphite and UV-531 having a purity ≥99% and ≥99% respectively. The recycled formulation is precisely formulated, supplementing the fresh white oil and adding stabilizing and anti-yellowing components to improve the compatibility and durability of the recycled white oil. It does not degrade or yellow during long-term recycling, matching the requirements of the spinning solution and ensuring fiber performance.

[0021] Preferably, the high-strength polyethylene is ultra-high molecular weight polyethylene with a weight-average relative molecular weight of 1 million to 5 million, a particle size of 100 to 200 mesh, and a bulk density of 0.3 to 0.5 g / cm³; the crude white oil is 75# to 100# industrial grade white oil with an initial kinematic viscosity of 75 to 80 mm² / s and a purity of ≥99.5%. Contaminants include UHMWPE micro powder, equipment corrosion particles, moisture, trace extractants, oxidation products, and color substances. The index ranges of UHMWPE and crude white oil are clearly defined to adapt to mainstream gel spinning systems. The equipment adopts an anti-corrosion coating to reduce rust and impurity introduction, reduce white oil adhesion loss, and improve process versatility and equipment life.

[0022] Preferably, in step S2, the filtration pressure of the plate and frame filter press is 0.3–0.5 MPa, the filtration temperature is 75–85°C, the filtration speed is 5–8 m³ / (m²·h), the filter cloth is made of polypropylene with a pore size of 0.1–0.2 μm, which can effectively trap adsorbent powder and impurities, limit the key parameters of pressure filtration and air stripping, ensure precise filter cloth selection, high-purity nitrogen without new impurities, and feature a sealed storage tank and polished pipeline design to prevent oxidation, leakage, and secondary pollution throughout the process, resulting in low white oil loss and more stable operation.

[0023] Preferably, the process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system also includes process monitoring and parameter adjustment steps, specifically: temperature sensors, pressure sensors, and liquid level sensors are respectively installed on the crude white oil storage tank, composite adsorption tank, chromatography adsorption tower, vacuum distillation tower, refined white oil blending tank, and refined white oil storage tank to monitor the temperature, pressure, and liquid level in each device in real time;

[0024] Sampling points were set up after pretreatment, primary composite adsorption, secondary chromatographic adsorption, vacuum distillation, and blending to meet standards. Samples were taken regularly to test the indicators of white oil, including purity, kinematic viscosity, color, transmittance, moisture content, extractant residue, and mechanical impurity content.

[0025] Based on monitoring data and test results, the operating parameters of each step are adjusted in real time, including heating temperature, stirring speed, adsorption time, distillation temperature and nitrogen flow rate, to ensure stable operation of the process and that the white oil purification effect and reuse quality meet the standards.

[0026] At the same time, a process operation log is established to record the operating parameters, test results and equipment operating status of each step. Online monitoring and sampling testing are added, parameters are adjusted in real time and operation is traceable, ensuring that the process is stable and meets the standards, significantly reducing white oil consumption and hazardous waste, with high extractant recovery rate, and outstanding environmental and economic benefits.

[0027] The beneficial effects of this invention are:

[0028] Through a five-stage closed-loop process and five customized formulas, this technology achieves deep purification and efficient recycling of waste white oil from high-strength polyethylene gel spinning. It boasts multiple significant effects and outstanding innovation. The proprietary pretreatment aids, composite adsorbents, modified silica gel, distillation additives, and recycling formulations solve the problems of incomplete purification and unstable recycling associated with traditional processes. Adsorption efficiency is increased by over 35%, resulting in white oil purity ≥99.98%, light transmittance ≥80%, and color ≤1. Moisture and extractant residues are extremely low, with indicators approaching those of fresh white oil. White oil recycling rate is ≥95%, fiber consumption is reduced from 20kg to less than 1kg, extractant recovery rate is ≥98%, adsorbent loss is reduced by 30%, and the oil remains stable even after more than 10 cycles. Fiber strength is ≥30cN / dtex, without affecting spinning performance. The process can significantly reduce hazardous waste generation by over 85%, achieve VOC emission standards, lower distillation temperature by 5–10℃, and reduce overall energy consumption by 30%. It is compatible with existing production lines, demonstrating outstanding industrialization and green production value. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the workflow proposed in this invention. Detailed Implementation

[0030] The present invention will be further explained below with reference to specific embodiments.

[0031] Reference Figure 1 Example 1

[0032] This embodiment proposes a process for deep purification and recycling of white oil in a high-strength polyethylene gel spinning system, including the following steps:

[0033] S1: Crude White Oil Collection and Pretreatment. Crude white oil generated from the high-strength polyethylene gel spinning extraction section, centrifugal degreasing, and drying tail gas condensation is collected and deposited into a crude white oil storage tank. Pretreatment aids are added to the crude white oil, and under a nitrogen protective atmosphere, it is heated at 70°C for 45 minutes to break the emulsion, with the stirring speed controlled at 175 r / min, to reduce the viscosity of the white oil and disrupt the oil-in-water / water-in-oil emulsion system. Free water is then separated by a high-efficiency oil-water separator. After settling and filtration, the free water is discharged in compliance with standards. The oil is then further processed by a vacuum flash evaporator at a vacuum of -0.08 MPa and a temperature of 70°C to remove dissolved water and low-boiling-point extractant. The low-boiling-point extractant is recovered by condensation and recycled. Used in the spinning extraction section, it is finally pre-filtered through a 70μm basket filter to remove large mechanical impurities, including UHMWPE micro powder, equipment rust particles, and kaolin powder, to obtain pretreated white oil. The pretreatment auxiliaries, based on the mass of crude white oil, include 0.3% demulsifier SP-169, 0.15% antioxidant 1010, and the balance being deionized water. The addition ratio of pretreatment auxiliaries to crude white oil is 1:60. Demulsifier SP-169 is a polyoxyethylene-polyoxypropylene block copolymer, and antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. During the pretreatment process, the nitrogen flow rate is 0.07 m³ / h.

[0034] S2: Primary composite adsorption purification. Pretreated white oil is introduced into a composite adsorption tank. Under a nitrogen protective atmosphere, the temperature is raised to 86℃, and the stirring speed is controlled at 135 r / min. A customized composite adsorbent is added at a ratio of 1.4% of the white oil mass. Stirring is performed for 1 hour, followed by heat adsorption at 82℃ to ensure the composite adsorbent fully adsorbs colloids, oxidation products, some pigments, and trace polar impurities from the white oil. After adsorption is complete, stirring is stopped, and the mixture is allowed to settle for 12 minutes. Subsequently, it is filtered through a plate and frame filter press at a pressure of 0.4 MPa, a temperature of 81℃, and a filtration rate of 7 m³ / (m²·h). The filtrate is collected, and the filter cake, a mixture of adsorbent and impurities, is disposed of after harmless treatment. During the adsorption process, nitrogen... The flow rate is 0.011 m³ / h to ensure an oxygen-free environment during adsorption, preventing oxidation of the white oil and avoiding adsorbent deactivation. The customized composite adsorbent, by weight, includes 69 parts activated clay, 15 parts modified activated carbon, 10 parts molecular sieve, 4 parts graphene oxide solution, and 2 parts cationic surfactant. The activated clay is natural bentonite activated at 330℃, with a specific surface area ≥200 m² / g and an adsorption capacity ≥150 mg / g. The modified activated carbon, by weight, includes 8% activated carbon, 1% 3-chloro-2-hydroxypropyltrimethylammonium chloride, 9% tannic acid, 42% 3wt% hydroxylamine hydrochloride solution, and 40% 10wt% sodium hydroxide solution. The molecular sieve... The 4A molecular sieve has a particle size of 2 mm; the graphene oxide solution concentration is 20 wt%, prepared using the Hummers method, and the graphene oxide sheet thickness is 1 nm; the cationic surfactant is octadecyltrimethylammonium chloride with a purity ≥98%; the preparation method of the customized composite adsorbent is as follows: first, activated carbon, oxidant, and 3-chloro-2-hydroxypropyltrimethylammonium chloride are mixed and refluxed at 75°C for 2 hours. The oxidant is selected from nitric acid, and the mass ratio of oxidant to activated carbon is 1:2. After reflux, tannic acid is added and ultrasonically dissolved for 70 minutes at an ultrasonic power of 350 W and an ultrasonic frequency of 27 kHz. Then, hydroxylamine hydrochloride solution and sodium hydroxide solution are added and ultrasonically dispersed for 50 minutes to adjust the reaction. The system pH value is 7.2. After filtration and washing to neutrality, it is dried at 107℃ for 2 hours to obtain modified activated carbon. Activated clay, modified activated carbon, and molecular sieve are mixed, and graphene oxide solution and cationic surfactant are added. The mixture is ultrasonically dispersed for 35 minutes at an ultrasonic power of 350W and an ultrasonic frequency of 27kHz. Subsequently, it is calcined at 430℃ for 2 hours at a calcination heating rate of 6℃ / min. After cooling to room temperature, it is pulverized to 90 mesh, sieved, and sealed for storage to obtain the customized composite adsorbent. The filtration pressure of the plate and frame filter press is 0.4MPa, the filtration temperature is 80℃, and the filtration speed is 6m³ / (m²·h). The filter cloth is made of polypropylene with a pore size of 0.1μm, which can effectively trap adsorbent powder and impurities.

[0035] S3: Secondary chromatography adsorption purification. The filtrate is passed into a chromatography adsorption tower filled with a composite adsorption bed. From top to bottom, the composite adsorption bed consists of a silica gel layer, an activated carbon layer, and a molecular sieve layer, separated by quartz sand pads. The white oil flow rate is controlled at 1 BV / h, the adsorption temperature at 40℃, and the adsorption pressure at 0.2 MPa. Deep adsorption is performed under a nitrogen protective atmosphere. After adsorption, the filtrate is precisely filtered through a series of 10μm→5μm→1μm→0.5μm security filters to remove the adsorbent. Micronized powder ensures the white oil is free of mechanical impurities. The silica gel is modified silica gel, with the following formula: 93 parts silica gel, 4 parts γ-aminopropyltriethoxysilane, and 3 parts deionized water. The modified silica gel is prepared by mixing silica gel with γ-aminopropyltriethoxysilane and deionized water, hydrolyzing it at 66°C for 2 hours, curing it at 135°C for 3 hours after hydrolysis, cooling it to room temperature, pulverizing it to 70 mesh, sieving it, and using it for later use. The activated carbon layer uses modified activated carbon, and the molecular sieve layer uses 4A molecular sieve.

[0036] S4: Three-stage vacuum distillation purification. A distillation-modified additive is added to the finely filtered white oil and stirred for 25 minutes at 110 r / min to ensure uniform dispersion. The mixture is then introduced into a vacuum distillation column, controlled at a vacuum of -0.095 MPa, a reboiler temperature of 210℃, a column top temperature of 140℃, a column reboiler heating rate of 4℃ / min, and a reflux ratio of 4:1. High-purity nitrogen (≥99.99%) is introduced during distillation for stripping at a flow rate of 0.2 m³ / h to enhance the removal of residual VOC extractant and odors. Light components are collected at the top of the column, condensed, and recovered. The extractant is recycled to the spinning extraction section. Impurities in the light components are... The incineration process collects refined white oil at the bottom of the column. After being cooled to 65°C by a cooler, the refined white oil is sent to an intermediate storage tank. The distillation column is filled with high-efficiency distillation packing material, which is stainless steel corrugated packing material, model 250Y, added at 17% of the column volume. The distillation yield is ≥98%. Nitrogen protection is used throughout the distillation process. The components of the distillation modification additive include antioxidant B225, deodorizing agent, and distillation aid. Antioxidant B225 is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:1. The deodorizing agent is a mixture of vanillin and citral in a mass ratio of 2:1, both with a purity of ≥99%. The distillation aid is dibutyl phthalate with a purity of ≥99.5%.

[0037] S5: Preparation and Recycling of Refined White Oil: The collected refined white oil is cooled to 45°C and sent to a refined white oil blending tank. Under a stirring speed of 90 r / min, fresh white oil, a stability regulator, and an anti-yellowing agent are added sequentially, and the mixture is stirred for 35 minutes to ensure uniform mixing of all components. Subsequently, the white oil indicators are tested: purity ≥99.98%, kinematic viscosity 78 mm² / s, color ≤1, light transmittance ≥80%, free of mechanical impurities, and odorless. After meeting the standards, it is pumped into a refined white oil storage tank, sealed with nitrogen at a pressure maintained at 0.02 MPa to prevent oxidation. Finally, the refined white oil is transported to the high-strength polyethylene gel spinning dissolution section for recycling in UHMW. PE powder is dissolved to achieve a closed-loop circulation. During the mixing process, nitrogen is introduced at a flow rate of 0.03 m³ / h to ensure an oxygen-free environment. The reused mixing formula is: 95 parts refined white oil, 4 parts fresh white oil, 0.7 parts stability modifier, and 0.3 parts anti-yellowing agent. The fresh white oil is 100# industrial grade white oil with a purity ≥99.99% and a kinematic viscosity of 78 mm² / s. The stability modifier is a mixture of calcium stearate and zinc stearate at a mass ratio of 3:2, both with a purity ≥98%. The anti-yellowing agent is a mixture of triphenyl phosphite and UV-531 at a mass ratio of 4:1, with triphenyl phosphite and UV-531 having a purity ≥99% and ≥99% respectively.

[0038] High-strength polyethylene is ultra-high molecular weight polyethylene with a weight-average relative molecular weight of 3 million, a particle size of 150 mesh, and a bulk density of 0.4 g / cm³; crude white oil is 100# industrial grade white oil with an initial kinematic viscosity of 78 mm² / s and a purity of ≥99.5%. Contaminants include UHMWPE micro powder, equipment corrosion particles, moisture, trace extractants, oxidation products, and color substances.

[0039] The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system also includes process monitoring and parameter adjustment steps. Specifically, temperature sensors, pressure sensors, and liquid level sensors are installed on the crude white oil storage tank, composite adsorption tank, chromatography adsorption tower, vacuum distillation tower, refined white oil blending tank, and refined white oil storage tank to monitor the temperature, pressure, and liquid level in each device in real time.

[0040] Sampling points were set up after pretreatment, primary composite adsorption, secondary chromatographic adsorption, vacuum distillation, and blending to meet standards. Samples were taken regularly to test the indicators of white oil, including purity, kinematic viscosity, color, transmittance, moisture content, extractant residue, and mechanical impurity content.

[0041] Based on monitoring data and test results, the operating parameters of each step are adjusted in real time, including heating temperature, stirring speed, adsorption time, distillation temperature and nitrogen flow rate, to ensure stable operation of the process and that the white oil purification effect and reuse quality meet the standards.

[0042] At the same time, a process operation log should be established to record the operating parameters, test results and equipment operating status of each step.

[0043] Reference Figure 1 Example 2

[0044] This embodiment proposes a process for deep purification and recycling of white oil in a high-strength polyethylene gel spinning system, including the following steps:

[0045] S1: Crude White Oil Collection and Pretreatment. Crude white oil generated from the high-strength polyethylene gel spinning extraction section, centrifugal degreasing, and drying tail gas condensation is collected and deposited into a crude white oil storage tank. Pretreatment aids are added to the crude white oil, and under a nitrogen protective atmosphere, it is heated at 70°C for 45 minutes to break the emulsion, with the stirring speed controlled at 175 r / min, to reduce the viscosity of the white oil and disrupt the oil-in-water / water-in-oil emulsion system. Free water is then separated by a high-efficiency oil-water separator. After settling and filtration, the free water is discharged in compliance with standards. The oil is then further processed by a vacuum flash evaporator at a vacuum of -0.08 MPa and a temperature of 70°C to remove dissolved water and low-boiling-point extractant. The low-boiling-point extractant is recovered by condensation and recycled. Used in the spinning extraction section, it is finally pre-filtered through a 70μm basket filter to remove large mechanical impurities, including UHMWPE micro powder, equipment rust particles, and kaolin powder, to obtain pretreated white oil. The pretreatment aids, based on the mass of crude white oil, include 0.2% demulsifier SP-169, 0.11% antioxidant 1010, and the balance is deionized water. The addition ratio of pretreatment aids to crude white oil is 1:60. Demulsifier SP-169 is a polyoxyethylene-polyoxypropylene block copolymer, and antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. During the pretreatment process, the nitrogen flow rate is 0.07 m³ / h.

[0046] S2: Primary composite adsorption purification. Pretreated white oil is introduced into a composite adsorption tank. Under a nitrogen protective atmosphere, the temperature is raised to 86℃, and the stirring speed is controlled at 135 r / min. A customized composite adsorbent is added at a ratio of 1.4% of the white oil mass. Stirring is performed for 1 hour, followed by heat adsorption at 82℃ to ensure the composite adsorbent fully adsorbs colloids, oxidation products, some pigments, and trace polar impurities from the white oil. After adsorption is complete, stirring is stopped, and the mixture is allowed to settle for 12 minutes. Subsequently, it is filtered through a plate and frame filter press at a pressure of 0.4 MPa, a temperature of 81℃, and a filtration rate of 7 m³ / (m²·h). The filtrate is collected, and the filter cake, a mixture of adsorbent and impurities, is disposed of after harmless treatment. During the adsorption process, nitrogen... The flow rate is 0.011 m³ / h to ensure an oxygen-free environment during adsorption, preventing oxidation of the white oil and avoiding adsorbent deactivation. The customized composite adsorbent, by weight, includes 69 parts activated clay, 15 parts modified activated carbon, 10 parts molecular sieve, 4 parts graphene oxide solution, and 2 parts cationic surfactant. The activated clay is natural bentonite activated at 330℃, with a specific surface area ≥200 m² / g and an adsorption capacity ≥150 mg / g. The modified activated carbon, by weight, includes 8% activated carbon, 1% 3-chloro-2-hydroxypropyltrimethylammonium chloride, 9% tannic acid, 42% 3wt% hydroxylamine hydrochloride solution, and 40% 10wt% sodium hydroxide solution. The molecular sieve... The 4A molecular sieve has a particle size of 2 mm; the graphene oxide solution concentration is 20 wt%, prepared using the Hummers method, and the graphene oxide sheet thickness is 1 nm; the cationic surfactant is octadecyltrimethylammonium chloride with a purity ≥98%; the preparation method of the customized composite adsorbent is as follows: first, activated carbon, oxidant, and 3-chloro-2-hydroxypropyltrimethylammonium chloride are mixed and refluxed at 75°C for 2 hours. The oxidant is selected from nitric acid, and the mass ratio of oxidant to activated carbon is 1:2. After reflux, tannic acid is added and ultrasonically dissolved for 70 minutes at an ultrasonic power of 350 W and an ultrasonic frequency of 27 kHz. Then, hydroxylamine hydrochloride solution and sodium hydroxide solution are added and ultrasonically dispersed for 50 minutes to adjust the reaction. The system pH value is 7.2. After filtration and washing to neutrality, it is dried at 107℃ for 2 hours to obtain modified activated carbon. Activated clay, modified activated carbon, and molecular sieve are mixed, and graphene oxide solution and cationic surfactant are added. The mixture is ultrasonically dispersed for 35 minutes at an ultrasonic power of 350W and an ultrasonic frequency of 27kHz. Subsequently, it is calcined at 430℃ for 2 hours at a calcination heating rate of 6℃ / min. After cooling to room temperature, it is pulverized to 90 mesh, sieved, and sealed for storage to obtain the customized composite adsorbent. The filtration pressure of the plate and frame filter press is 0.4MPa, the filtration temperature is 80℃, and the filtration speed is 6m³ / (m²·h). The filter cloth is made of polypropylene with a pore size of 0.1μm, which can effectively trap adsorbent powder and impurities.

[0047] S3: Secondary chromatography adsorption purification. The filtrate is passed into a chromatography adsorption tower filled with a composite adsorption bed. From top to bottom, the composite adsorption bed consists of a silica gel layer, an activated carbon layer, and a molecular sieve layer, separated by quartz sand pads. The white oil flow rate is controlled at 1 BV / h, the adsorption temperature at 40℃, and the adsorption pressure at 0.2 MPa. Deep adsorption is performed under a nitrogen protective atmosphere. After adsorption, the filtrate is precisely filtered through a series of 10μm→5μm→1μm→0.5μm security filters to remove the adsorbent. Micronized powder ensures the white oil is free of mechanical impurities. The silica gel is modified silica gel, with the following formula: 93 parts silica gel, 4 parts γ-aminopropyltriethoxysilane, and 3 parts deionized water. The modified silica gel is prepared by mixing silica gel with γ-aminopropyltriethoxysilane and deionized water, hydrolyzing it at 66°C for 2 hours, curing it at 135°C for 3 hours after hydrolysis, cooling it to room temperature, pulverizing it to 70 mesh, sieving it, and using it for later use. The activated carbon layer uses modified activated carbon, and the molecular sieve layer uses 4A molecular sieve.

[0048] S4: Three-stage vacuum distillation purification. A distillation-modified additive is added to the finely filtered white oil and stirred for 25 minutes at 110 r / min to ensure uniform dispersion. The mixture is then introduced into a vacuum distillation column, controlled at a vacuum of -0.095 MPa, a reboiler temperature of 210℃, a column top temperature of 140℃, a column reboiler heating rate of 4℃ / min, and a reflux ratio of 4:1. High-purity nitrogen (≥99.99%) is introduced during distillation for stripping at a flow rate of 0.2 m³ / h to enhance the removal of residual VOC extractant and odors. Light components are collected at the top of the column, condensed, and recovered. The extractant is recycled to the spinning extraction section. Impurities in the light components are... The incineration process collects refined white oil at the bottom of the column. After being cooled to 65°C by a cooler, the refined white oil is sent to an intermediate storage tank. The distillation column is filled with high-efficiency distillation packing material, which is stainless steel corrugated packing material, model 250Y, added at 17% of the column volume. The distillation yield is ≥98%. Nitrogen protection is used throughout the distillation process. The components of the distillation modification additive include antioxidant B225, deodorizing agent, and distillation aid. Antioxidant B225 is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:1. The deodorizing agent is a mixture of vanillin and citral in a mass ratio of 2:1, both with a purity of ≥99%. The distillation aid is dibutyl phthalate with a purity of ≥99.5%.

[0049] S5: Preparation and Recycling of Refined White Oil: The collected refined white oil is cooled to 45°C and sent to a refined white oil blending tank. Under a stirring speed of 90 r / min, fresh white oil, a stability regulator, and an anti-yellowing agent are added sequentially, and the mixture is stirred for 35 minutes to ensure uniform mixing of all components. Subsequently, the white oil indicators are tested: purity ≥99.98%, kinematic viscosity 78 mm² / s, color ≤1, light transmittance ≥80%, free of mechanical impurities, and odorless. After meeting the standards, it is pumped into a refined white oil storage tank, sealed with nitrogen at a pressure maintained at 0.02 MPa to prevent oxidation. Finally, the refined white oil is transported to the high-strength polyethylene gel spinning dissolution section for recycling in UHMW. PE powder is dissolved to achieve a closed-loop circulation. During the mixing process, nitrogen is introduced at a flow rate of 0.03 m³ / h to ensure an oxygen-free environment. The reused mixing formula is: 95 parts refined white oil, 4 parts fresh white oil, 0.7 parts stability modifier, and 0.3 parts anti-yellowing agent. The fresh white oil is 100# industrial grade white oil with a purity ≥99.99% and a kinematic viscosity of 78 mm² / s. The stability modifier is a mixture of calcium stearate and zinc stearate at a mass ratio of 3:2, both with a purity ≥98%. The anti-yellowing agent is a mixture of triphenyl phosphite and UV-531 at a mass ratio of 4:1, with triphenyl phosphite and UV-531 having a purity ≥99% and ≥99% respectively.

[0050] High-strength polyethylene is ultra-high molecular weight polyethylene with a weight-average relative molecular weight of 3 million, a particle size of 150 mesh, and a bulk density of 0.4 g / cm³; crude white oil is 100# industrial grade white oil with an initial kinematic viscosity of 78 mm² / s and a purity of ≥99.5%. Contaminants include UHMWPE micro powder, equipment corrosion particles, moisture, trace extractants, oxidation products, and color substances.

[0051] The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system also includes process monitoring and parameter adjustment steps. Specifically, temperature sensors, pressure sensors, and liquid level sensors are installed on the crude white oil storage tank, composite adsorption tank, chromatography adsorption tower, vacuum distillation tower, refined white oil blending tank, and refined white oil storage tank to monitor the temperature, pressure, and liquid level in each device in real time.

[0052] Sampling points were set up after pretreatment, primary composite adsorption, secondary chromatographic adsorption, vacuum distillation, and blending to meet standards. Samples were taken regularly to test the indicators of white oil, including purity, kinematic viscosity, color, transmittance, moisture content, extractant residue, and mechanical impurity content.

[0053] Based on monitoring data and test results, the operating parameters of each step are adjusted in real time, including heating temperature, stirring speed, adsorption time, distillation temperature and nitrogen flow rate, to ensure stable operation of the process and that the white oil purification effect and reuse quality meet the standards.

[0054] At the same time, a process operation log should be established to record the operating parameters, test results and equipment operating status of each step.

[0055] Reference Figure 1 Example 3

[0056] This embodiment proposes a process for deep purification and recycling of white oil in a high-strength polyethylene gel spinning system, including the following steps:

[0057] S1: Crude White Oil Collection and Pretreatment. Crude white oil generated from the high-strength polyethylene gel spinning extraction section, centrifugal degreasing, and drying tail gas condensation is collected and deposited into a crude white oil storage tank. Pretreatment aids are added to the crude white oil, and under a nitrogen protective atmosphere, it is heated at 70°C for 45 minutes to break the emulsion, with the stirring speed controlled at 175 r / min, to reduce the viscosity of the white oil and disrupt the oil-in-water / water-in-oil emulsion system. Free water is then separated by a high-efficiency oil-water separator. After settling and filtration, the free water is discharged in compliance with standards. The oil is then further processed by a vacuum flash evaporator at a vacuum of -0.08 MPa and a temperature of 70°C to remove dissolved water and low-boiling-point extractant. The low-boiling-point extractant is recovered by condensation and recycled. Used in the spinning extraction section, it is finally pre-filtered through a 70μm basket filter to remove large mechanical impurities, including UHMWPE micro powder, equipment rust particles, and kaolin powder, to obtain pretreated white oil. The pretreatment aids, based on the mass of crude white oil, include 0.2% demulsifier SP-169, 0.10% antioxidant 1010, and the balance is deionized water. The addition ratio of pretreatment aids to crude white oil is 1:60. Demulsifier SP-169 is a polyoxyethylene polyoxypropylene block copolymer, and antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. During the pretreatment process, the nitrogen flow rate is 0.07 m³ / h.

[0058] S2: Primary composite adsorption purification. Pretreated white oil is introduced into a composite adsorption tank. Under a nitrogen protective atmosphere, the temperature is raised to 86℃, and the stirring speed is controlled at 135 r / min. A customized composite adsorbent is added at a ratio of 1.4% of the white oil mass. Stirring is performed for 1 hour, followed by heat adsorption at 82℃ to ensure the composite adsorbent fully adsorbs colloids, oxidation products, some pigments, and trace polar impurities from the white oil. After adsorption is complete, stirring is stopped, and the mixture is allowed to settle for 12 minutes. Subsequently, it is filtered through a plate and frame filter press at a pressure of 0.4 MPa, a temperature of 81℃, and a filtration rate of 7 m³ / (m²·h). The filtrate is collected, and the filter cake, a mixture of adsorbent and impurities, is disposed of after harmless treatment. During the adsorption process, nitrogen... The flow rate is 0.011 m³ / h to ensure an oxygen-free environment during adsorption, preventing oxidation of the white oil and avoiding adsorbent deactivation. The customized composite adsorbent, by weight, includes 69 parts activated clay, 15 parts modified activated carbon, 10 parts molecular sieve, 4 parts graphene oxide solution, and 2 parts cationic surfactant. The activated clay is natural bentonite activated at 330℃, with a specific surface area ≥200 m² / g and an adsorption capacity ≥150 mg / g. The modified activated carbon, by weight, includes 8% activated carbon, 1% 3-chloro-2-hydroxypropyltrimethylammonium chloride, 9% tannic acid, 42% 3wt% hydroxylamine hydrochloride solution, and 40% 10wt% sodium hydroxide solution. The molecular sieve... The 4A molecular sieve has a particle size of 2 mm; the graphene oxide solution concentration is 20 wt%, prepared using the Hummers method, and the graphene oxide sheet thickness is 1 nm; the cationic surfactant is octadecyltrimethylammonium chloride with a purity ≥98%; the preparation method of the customized composite adsorbent is as follows: first, activated carbon, oxidant, and 3-chloro-2-hydroxypropyltrimethylammonium chloride are mixed and refluxed at 75°C for 2 hours. The oxidant is selected from nitric acid, and the mass ratio of oxidant to activated carbon is 1:2. After reflux, tannic acid is added and ultrasonically dissolved for 70 minutes at an ultrasonic power of 350 W and an ultrasonic frequency of 27 kHz. Then, hydroxylamine hydrochloride solution and sodium hydroxide solution are added and ultrasonically dispersed for 50 minutes to adjust the reaction. The system pH value is 7.2. After filtration and washing to neutrality, it is dried at 107℃ for 2 hours to obtain modified activated carbon. Activated clay, modified activated carbon, and molecular sieve are mixed, and graphene oxide solution and cationic surfactant are added. The mixture is ultrasonically dispersed for 35 minutes at an ultrasonic power of 350W and an ultrasonic frequency of 27kHz. Subsequently, it is calcined at 430℃ for 2 hours at a calcination heating rate of 6℃ / min. After cooling to room temperature, it is pulverized to 90 mesh, sieved, and sealed for storage to obtain the customized composite adsorbent. The filtration pressure of the plate and frame filter press is 0.4MPa, the filtration temperature is 80℃, and the filtration speed is 6m³ / (m²·h). The filter cloth is made of polypropylene with a pore size of 0.1μm, which can effectively trap adsorbent powder and impurities.

[0059] S3: Secondary chromatography adsorption purification. The filtrate is passed into a chromatography adsorption tower filled with a composite adsorption bed. From top to bottom, the composite adsorption bed consists of a silica gel layer, an activated carbon layer, and a molecular sieve layer, separated by quartz sand pads. The white oil flow rate is controlled at 1 BV / h, the adsorption temperature at 40℃, and the adsorption pressure at 0.2 MPa. Deep adsorption is performed under a nitrogen protective atmosphere. After adsorption, the filtrate is precisely filtered through a series of 10μm→5μm→1μm→0.5μm security filters to remove the adsorbent. Micronized powder ensures the white oil is free of mechanical impurities. The silica gel is modified silica gel, with the following formula: 93 parts silica gel, 4 parts γ-aminopropyltriethoxysilane, and 3 parts deionized water. The modified silica gel is prepared by mixing silica gel with γ-aminopropyltriethoxysilane and deionized water, hydrolyzing it at 66°C for 2 hours, curing it at 135°C for 3 hours after hydrolysis, cooling it to room temperature, pulverizing it to 70 mesh, sieving it, and using it for later use. The activated carbon layer uses modified activated carbon, and the molecular sieve layer uses 4A molecular sieve.

[0060] S4: Three-stage vacuum distillation purification. A distillation-modified additive is added to the finely filtered white oil and stirred for 25 minutes at 110 r / min to ensure uniform dispersion. The mixture is then introduced into a vacuum distillation column, controlled at a vacuum of -0.095 MPa, a reboiler temperature of 210℃, a column top temperature of 140℃, a column reboiler heating rate of 4℃ / min, and a reflux ratio of 4:1. High-purity nitrogen (≥99.99%) is introduced during distillation for stripping at a flow rate of 0.2 m³ / h to enhance the removal of residual VOC extractant and odors. Light components are collected at the top of the column, condensed, and recovered. The extractant is recycled to the spinning extraction section. Impurities in the light components are... The incineration process collects refined white oil at the bottom of the column. After being cooled to 65°C by a cooler, the refined white oil is sent to an intermediate storage tank. The distillation column is filled with high-efficiency distillation packing material, which is stainless steel corrugated packing material, model 250Y, added at 17% of the column volume. The distillation yield is ≥98%. Nitrogen protection is used throughout the distillation process. The components of the distillation modification additive include antioxidant B225, deodorizing agent, and distillation aid. Antioxidant B225 is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:1. The deodorizing agent is a mixture of vanillin and citral in a mass ratio of 2:1, both with a purity of ≥99%. The distillation aid is dibutyl phthalate with a purity of ≥99.5%.

[0061] S5: Preparation and Recycling of Refined White Oil: The collected refined white oil is cooled to 45°C and sent to a refined white oil blending tank. Under a stirring speed of 90 r / min, fresh white oil, a stability regulator, and an anti-yellowing agent are added sequentially, and the mixture is stirred for 35 minutes to ensure uniform mixing of all components. Subsequently, the white oil indicators are tested: purity ≥99.98%, kinematic viscosity 78 mm² / s, color ≤1, light transmittance ≥80%, free of mechanical impurities, and odorless. After meeting the standards, it is pumped into a refined white oil storage tank, sealed with nitrogen at a pressure maintained at 0.02 MPa to prevent oxidation. Finally, the refined white oil is transported to the high-strength polyethylene gel spinning dissolution section for recycling in UHMW. PE powder is dissolved to achieve a closed-loop circulation. During the mixing process, nitrogen is introduced at a flow rate of 0.03 m³ / h to ensure an oxygen-free environment. The reused mixing formula is: 95 parts refined white oil, 4 parts fresh white oil, 0.7 parts stability modifier, and 0.3 parts anti-yellowing agent. The fresh white oil is 100# industrial grade white oil with a purity ≥99.99% and a kinematic viscosity of 78 mm² / s. The stability modifier is a mixture of calcium stearate and zinc stearate at a mass ratio of 3:2, both with a purity ≥98%. The anti-yellowing agent is a mixture of triphenyl phosphite and UV-531 at a mass ratio of 4:1, with triphenyl phosphite and UV-531 having a purity ≥99% and ≥99% respectively.

[0062] High-strength polyethylene is ultra-high molecular weight polyethylene with a weight-average relative molecular weight of 3 million, a particle size of 150 mesh, and a bulk density of 0.4 g / cm³; crude white oil is 100# industrial grade white oil with an initial kinematic viscosity of 78 mm² / s and a purity of ≥99.5%. Contaminants include UHMWPE micro powder, equipment corrosion particles, moisture, trace extractants, oxidation products, and color substances.

[0063] The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system also includes process monitoring and parameter adjustment steps. Specifically, temperature sensors, pressure sensors, and liquid level sensors are installed on the crude white oil storage tank, composite adsorption tank, chromatography adsorption tower, vacuum distillation tower, refined white oil blending tank, and refined white oil storage tank to monitor the temperature, pressure, and liquid level in each device in real time.

[0064] Sampling points were set up after pretreatment, primary composite adsorption, secondary chromatographic adsorption, vacuum distillation, and blending to meet standards. Samples were taken regularly to test the indicators of white oil, including purity, kinematic viscosity, color, transmittance, moisture content, extractant residue, and mechanical impurity content.

[0065] Based on monitoring data and test results, the operating parameters of each step are adjusted in real time, including heating temperature, stirring speed, adsorption time, distillation temperature and nitrogen flow rate, to ensure stable operation of the process and that the white oil purification effect and reuse quality meet the standards.

[0066] At the same time, a process operation log should be established to record the operating parameters, test results and equipment operating status of each step.

[0067] Reference Figure 1 Example 4

[0068] This embodiment proposes a process for deep purification and recycling of white oil in a high-strength polyethylene gel spinning system, including the following steps:

[0069] S1: Crude White Oil Collection and Pretreatment. Crude white oil generated from the high-strength polyethylene gel spinning extraction section, centrifugal degreasing, and drying tail gas condensation is collected and deposited into a crude white oil storage tank. Pretreatment aids are added to the crude white oil, and under a nitrogen protective atmosphere, it is heated at 70°C for 45 minutes to break the emulsion, with the stirring speed controlled at 175 r / min, to reduce the viscosity of the white oil and disrupt the oil-in-water / water-in-oil emulsion system. Free water is then separated by a high-efficiency oil-water separator. After settling and filtration, the free water is discharged in compliance with standards. The oil is then further processed by a vacuum flash evaporator at a vacuum of -0.08 MPa and a temperature of 70°C to remove dissolved water and low-boiling-point extractant. The low-boiling-point extractant is recovered by condensation and recycled. Used in the spinning extraction section, it is finally pre-filtered through a 70μm basket filter to remove large mechanical impurities, including UHMWPE micro powder, equipment rust particles, and kaolin powder, to obtain pretreated white oil. The pretreatment aids, based on the mass of crude white oil, include 0.1% demulsifier SP-169, 0.08% antioxidant 1010, and the balance is deionized water. The addition ratio of pretreatment aids to crude white oil is 1:60. Demulsifier SP-169 is a polyoxyethylene-polyoxypropylene block copolymer, and antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. During the pretreatment process, the nitrogen flow rate is 0.07 m³ / h.

[0070] S2: Primary composite adsorption purification. Pretreated white oil is introduced into a composite adsorption tank. Under a nitrogen protective atmosphere, the temperature is raised to 86℃, and the stirring speed is controlled at 135 r / min. A customized composite adsorbent is added at a ratio of 1.4% of the white oil mass. Stirring is performed for 1 hour, followed by heat adsorption at 82℃ to ensure the composite adsorbent fully adsorbs colloids, oxidation products, some pigments, and trace polar impurities from the white oil. After adsorption is complete, stirring is stopped, and the mixture is allowed to settle for 12 minutes. Subsequently, it is filtered through a plate and frame filter press at a pressure of 0.4 MPa, a temperature of 81℃, and a filtration rate of 7 m³ / (m²·h). The filtrate is collected, and the filter cake, a mixture of adsorbent and impurities, is disposed of after harmless treatment. During the adsorption process, nitrogen... The flow rate is 0.011 m³ / h to ensure an oxygen-free environment during adsorption, preventing oxidation of the white oil and avoiding adsorbent deactivation. The customized composite adsorbent, by weight, includes 69 parts activated clay, 15 parts modified activated carbon, 10 parts molecular sieve, 4 parts graphene oxide solution, and 2 parts cationic surfactant. The activated clay is natural bentonite activated at 330℃, with a specific surface area ≥200 m² / g and an adsorption capacity ≥150 mg / g. The modified activated carbon, by weight, includes 8% activated carbon, 1% 3-chloro-2-hydroxypropyltrimethylammonium chloride, 9% tannic acid, 42% 3wt% hydroxylamine hydrochloride solution, and 40% 10wt% sodium hydroxide solution. The molecular sieve... The 4A molecular sieve has a particle size of 2 mm; the graphene oxide solution concentration is 20 wt%, prepared using the Hummers method, and the graphene oxide sheet thickness is 1 nm; the cationic surfactant is octadecyltrimethylammonium chloride with a purity ≥98%; the preparation method of the customized composite adsorbent is as follows: first, activated carbon, oxidant, and 3-chloro-2-hydroxypropyltrimethylammonium chloride are mixed and refluxed at 75°C for 2 hours. The oxidant is selected from nitric acid, and the mass ratio of oxidant to activated carbon is 1:2. After reflux, tannic acid is added and ultrasonically dissolved for 70 minutes at an ultrasonic power of 350 W and an ultrasonic frequency of 27 kHz. Then, hydroxylamine hydrochloride solution and sodium hydroxide solution are added and ultrasonically dispersed for 50 minutes to adjust the reaction. The system pH value is 7.2. After filtration and washing to neutrality, it is dried at 107℃ for 2 hours to obtain modified activated carbon. Activated clay, modified activated carbon, and molecular sieve are mixed, and graphene oxide solution and cationic surfactant are added. The mixture is ultrasonically dispersed for 35 minutes at an ultrasonic power of 350W and an ultrasonic frequency of 27kHz. Subsequently, it is calcined at 430℃ for 2 hours at a calcination heating rate of 6℃ / min. After cooling to room temperature, it is pulverized to 90 mesh, sieved, and sealed for storage to obtain the customized composite adsorbent. The filtration pressure of the plate and frame filter press is 0.4MPa, the filtration temperature is 80℃, and the filtration speed is 6m³ / (m²·h). The filter cloth is made of polypropylene with a pore size of 0.1μm, which can effectively trap adsorbent powder and impurities.

[0071] S3: Secondary chromatography adsorption purification. The filtrate is passed into a chromatography adsorption tower filled with a composite adsorption bed. From top to bottom, the composite adsorption bed consists of a silica gel layer, an activated carbon layer, and a molecular sieve layer, separated by quartz sand pads. The white oil flow rate is controlled at 1 BV / h, the adsorption temperature at 40℃, and the adsorption pressure at 0.2 MPa. Deep adsorption is performed under a nitrogen protective atmosphere. After adsorption, the filtrate is precisely filtered through a series of 10μm→5μm→1μm→0.5μm security filters to remove the adsorbent. Micronized powder ensures the white oil is free of mechanical impurities. The silica gel is modified silica gel, with the following formula: 93 parts silica gel, 4 parts γ-aminopropyltriethoxysilane, and 3 parts deionized water. The modified silica gel is prepared by mixing silica gel with γ-aminopropyltriethoxysilane and deionized water, hydrolyzing it at 66°C for 2 hours, curing it at 135°C for 3 hours after hydrolysis, cooling it to room temperature, pulverizing it to 70 mesh, sieving it, and using it for later use. The activated carbon layer uses modified activated carbon, and the molecular sieve layer uses 4A molecular sieve.

[0072] S4: Three-stage vacuum distillation purification. A distillation-modified additive is added to the finely filtered white oil and stirred for 25 minutes at 110 r / min to ensure uniform dispersion. The mixture is then introduced into a vacuum distillation column, controlled at a vacuum of -0.095 MPa, a reboiler temperature of 210℃, a column top temperature of 140℃, a column reboiler heating rate of 4℃ / min, and a reflux ratio of 4:1. High-purity nitrogen (≥99.99%) is introduced during distillation for stripping at a flow rate of 0.2 m³ / h to enhance the removal of residual VOC extractant and odors. Light components are collected at the top of the column, condensed, and recovered. The extractant is recycled to the spinning extraction section. Impurities in the light components are... The incineration process collects refined white oil at the bottom of the column. After being cooled to 65°C by a cooler, the refined white oil is sent to an intermediate storage tank. The distillation column is filled with high-efficiency distillation packing material, which is stainless steel corrugated packing material, model 250Y, added at 17% of the column volume. The distillation yield is ≥98%. Nitrogen protection is used throughout the distillation process. The components of the distillation modification additive include antioxidant B225, deodorizing agent, and distillation aid. Antioxidant B225 is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:1. The deodorizing agent is a mixture of vanillin and citral in a mass ratio of 2:1, both with a purity of ≥99%. The distillation aid is dibutyl phthalate with a purity of ≥99.5%.

[0073] S5: Preparation and Recycling of Refined White Oil: The collected refined white oil is cooled to 45°C and sent to a refined white oil blending tank. Under a stirring speed of 90 r / min, fresh white oil, a stability regulator, and an anti-yellowing agent are added sequentially, and the mixture is stirred for 35 minutes to ensure uniform mixing of all components. Subsequently, the white oil indicators are tested: purity ≥99.98%, kinematic viscosity 78 mm² / s, color ≤1, light transmittance ≥80%, free of mechanical impurities, and odorless. After meeting the standards, it is pumped into a refined white oil storage tank, sealed with nitrogen at a pressure maintained at 0.02 MPa to prevent oxidation. Finally, the refined white oil is transported to the high-strength polyethylene gel spinning dissolution section for recycling in UHMW. PE powder is dissolved to achieve a closed-loop circulation. During the mixing process, nitrogen is introduced at a flow rate of 0.03 m³ / h to ensure an oxygen-free environment. The reused mixing formula is: 95 parts refined white oil, 4 parts fresh white oil, 0.7 parts stability modifier, and 0.3 parts anti-yellowing agent. The fresh white oil is 100# industrial grade white oil with a purity ≥99.99% and a kinematic viscosity of 78 mm² / s. The stability modifier is a mixture of calcium stearate and zinc stearate at a mass ratio of 3:2, both with a purity ≥98%. The anti-yellowing agent is a mixture of triphenyl phosphite and UV-531 at a mass ratio of 4:1, with triphenyl phosphite and UV-531 having a purity ≥99% and ≥99% respectively.

[0074] High-strength polyethylene is ultra-high molecular weight polyethylene with a weight-average relative molecular weight of 3 million, a particle size of 150 mesh, and a bulk density of 0.4 g / cm³; crude white oil is 100# industrial grade white oil with an initial kinematic viscosity of 78 mm² / s and a purity of ≥99.5%. Contaminants include UHMWPE micro powder, equipment corrosion particles, moisture, trace extractants, oxidation products, and color substances.

[0075] The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system also includes process monitoring and parameter adjustment steps. Specifically, temperature sensors, pressure sensors, and liquid level sensors are installed on the crude white oil storage tank, composite adsorption tank, chromatography adsorption tower, vacuum distillation tower, refined white oil blending tank, and refined white oil storage tank to monitor the temperature, pressure, and liquid level in each device in real time.

[0076] Sampling points were set up after pretreatment, primary composite adsorption, secondary chromatographic adsorption, vacuum distillation, and blending to meet standards. Samples were taken regularly to test the indicators of white oil, including purity, kinematic viscosity, color, transmittance, moisture content, extractant residue, and mechanical impurity content.

[0077] Based on monitoring data and test results, the operating parameters of each step are adjusted in real time, including heating temperature, stirring speed, adsorption time, distillation temperature and nitrogen flow rate, to ensure stable operation of the process and that the white oil purification effect and reuse quality meet the standards.

[0078] At the same time, a process operation log should be established to record the operating parameters, test results and equipment operating status of each step.

[0079] Reference Figure 1 Example 5

[0080] This embodiment proposes a process for deep purification and recycling of white oil in a high-strength polyethylene gel spinning system, including the following steps:

[0081] S1: Crude White Oil Collection and Pretreatment. Crude white oil generated from the high-strength polyethylene gel spinning extraction section, centrifugal degreasing, and drying tail gas condensation is collected and deposited into a crude white oil storage tank. Pretreatment aids are added to the crude white oil, and under a nitrogen protective atmosphere, it is heated at 70°C for 45 minutes to break the emulsion, with the stirring speed controlled at 175 r / min, to reduce the viscosity of the white oil and disrupt the oil-in-water / water-in-oil emulsion system. Free water is then separated by a high-efficiency oil-water separator. After settling and filtration, the free water is discharged in compliance with standards. The oil is then further processed by a vacuum flash evaporator at a vacuum of -0.08 MPa and a temperature of 70°C to remove dissolved water and low-boiling-point extractant. The low-boiling-point extractant is recovered by condensation and recycled. Used in the spinning extraction section, it is finally pre-filtered through a 70μm basket filter to remove large mechanical impurities, including UHMWPE micro powder, equipment rust particles, and kaolin powder, to obtain pretreated white oil. The pretreatment aids, based on the mass of crude white oil, include 0.1% demulsifier SP-169, 0.05% antioxidant 1010, and the balance is deionized water. The addition ratio of pretreatment aids to crude white oil is 1:60. Demulsifier SP-169 is a polyoxyethylene-polyoxypropylene block copolymer, and antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. During the pretreatment process, the nitrogen flow rate is 0.07 m³ / h.

[0082] S2: Primary composite adsorption purification. Pretreated white oil is introduced into a composite adsorption tank. Under a nitrogen protective atmosphere, the temperature is raised to 86℃, and the stirring speed is controlled at 135 r / min. A customized composite adsorbent is added at a ratio of 1.4% of the white oil mass. Stirring is performed for 1 hour, followed by heat adsorption at 82℃ to ensure the composite adsorbent fully adsorbs colloids, oxidation products, some pigments, and trace polar impurities from the white oil. After adsorption is complete, stirring is stopped, and the mixture is allowed to settle for 12 minutes. Subsequently, it is filtered through a plate and frame filter press at a pressure of 0.4 MPa, a temperature of 81℃, and a filtration rate of 7 m³ / (m²·h). The filtrate is collected, and the filter cake, a mixture of adsorbent and impurities, is disposed of after harmless treatment. During the adsorption process, nitrogen... The flow rate is 0.011 m³ / h to ensure an oxygen-free environment during adsorption, preventing oxidation of the white oil and avoiding adsorbent deactivation. The customized composite adsorbent, by weight, includes 69 parts activated clay, 15 parts modified activated carbon, 10 parts molecular sieve, 4 parts graphene oxide solution, and 2 parts cationic surfactant. The activated clay is natural bentonite activated at 330℃, with a specific surface area ≥200 m² / g and an adsorption capacity ≥150 mg / g. The modified activated carbon, by weight, includes 8% activated carbon, 1% 3-chloro-2-hydroxypropyltrimethylammonium chloride, 9% tannic acid, 42% 3wt% hydroxylamine hydrochloride solution, and 40% 10wt% sodium hydroxide solution. The molecular sieve... The 4A molecular sieve has a particle size of 2 mm; the graphene oxide solution concentration is 20 wt%, prepared using the Hummers method, and the graphene oxide sheet thickness is 1 nm; the cationic surfactant is octadecyltrimethylammonium chloride with a purity ≥98%; the preparation method of the customized composite adsorbent is as follows: first, activated carbon, oxidant, and 3-chloro-2-hydroxypropyltrimethylammonium chloride are mixed and refluxed at 75°C for 2 hours. The oxidant is selected from nitric acid, and the mass ratio of oxidant to activated carbon is 1:2. After reflux, tannic acid is added and ultrasonically dissolved for 70 minutes at an ultrasonic power of 350 W and an ultrasonic frequency of 27 kHz. Then, hydroxylamine hydrochloride solution and sodium hydroxide solution are added and ultrasonically dispersed for 50 minutes to adjust the reaction. The system pH value is 7.2. After filtration and washing to neutrality, it is dried at 107℃ for 2 hours to obtain modified activated carbon. Activated clay, modified activated carbon, and molecular sieve are mixed, and graphene oxide solution and cationic surfactant are added. The mixture is ultrasonically dispersed for 35 minutes at an ultrasonic power of 350W and an ultrasonic frequency of 27kHz. Subsequently, it is calcined at 430℃ for 2 hours at a calcination heating rate of 6℃ / min. After cooling to room temperature, it is pulverized to 90 mesh, sieved, and sealed for storage to obtain the customized composite adsorbent. The filtration pressure of the plate and frame filter press is 0.4MPa, the filtration temperature is 80℃, and the filtration speed is 6m³ / (m²·h). The filter cloth is made of polypropylene with a pore size of 0.1μm, which can effectively trap adsorbent powder and impurities.

[0083] S3: Secondary chromatography adsorption purification. The filtrate is passed into a chromatography adsorption tower filled with a composite adsorption bed. From top to bottom, the composite adsorption bed consists of a silica gel layer, an activated carbon layer, and a molecular sieve layer, separated by quartz sand pads. The white oil flow rate is controlled at 1 BV / h, the adsorption temperature at 40℃, and the adsorption pressure at 0.2 MPa. Deep adsorption is performed under a nitrogen protective atmosphere. After adsorption, the filtrate is precisely filtered through a series of 10μm→5μm→1μm→0.5μm security filters to remove the adsorbent. Micronized powder ensures the white oil is free of mechanical impurities. The silica gel is modified silica gel, with the following formula: 93 parts silica gel, 4 parts γ-aminopropyltriethoxysilane, and 3 parts deionized water. The modified silica gel is prepared by mixing silica gel with γ-aminopropyltriethoxysilane and deionized water, hydrolyzing it at 66°C for 2 hours, curing it at 135°C for 3 hours after hydrolysis, cooling it to room temperature, pulverizing it to 70 mesh, sieving it, and using it for later use. The activated carbon layer uses modified activated carbon, and the molecular sieve layer uses 4A molecular sieve.

[0084] S4: Three-stage vacuum distillation purification. A distillation-modified additive is added to the finely filtered white oil and stirred for 25 minutes at 110 r / min to ensure uniform dispersion. The mixture is then introduced into a vacuum distillation column, controlled at a vacuum of -0.095 MPa, a reboiler temperature of 210℃, a column top temperature of 140℃, a column reboiler heating rate of 4℃ / min, and a reflux ratio of 4:1. High-purity nitrogen (≥99.99%) is introduced during distillation for stripping at a flow rate of 0.2 m³ / h to enhance the removal of residual VOC extractant and odors. Light components are collected at the top of the column, condensed, and recovered. The extractant is recycled to the spinning extraction section. Impurities in the light components are... The incineration process collects refined white oil at the bottom of the column. After being cooled to 65°C by a cooler, the refined white oil is sent to an intermediate storage tank. The distillation column is filled with high-efficiency distillation packing material, which is stainless steel corrugated packing material, model 250Y, added at 17% of the column volume. The distillation yield is ≥98%. Nitrogen protection is used throughout the distillation process. The components of the distillation modification additive include antioxidant B225, deodorizing agent, and distillation aid. Antioxidant B225 is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:1. The deodorizing agent is a mixture of vanillin and citral in a mass ratio of 2:1, both with a purity of ≥99%. The distillation aid is dibutyl phthalate with a purity of ≥99.5%.

[0085] S5: Preparation and Recycling of Refined White Oil: The collected refined white oil is cooled to 45°C and sent to a refined white oil blending tank. Under a stirring speed of 90 r / min, fresh white oil, a stability regulator, and an anti-yellowing agent are added sequentially, and the mixture is stirred for 35 minutes to ensure uniform mixing of all components. Subsequently, the white oil indicators are tested: purity ≥99.98%, kinematic viscosity 78 mm² / s, color ≤1, light transmittance ≥80%, free of mechanical impurities, and odorless. After meeting the standards, it is pumped into a refined white oil storage tank, sealed with nitrogen at a pressure maintained at 0.02 MPa to prevent oxidation. Finally, the refined white oil is transported to the high-strength polyethylene gel spinning dissolution section for recycling in UHMW. PE powder is dissolved to achieve a closed-loop circulation. During the mixing process, nitrogen is introduced at a flow rate of 0.03 m³ / h to ensure an oxygen-free environment. The reused mixing formula is: 95 parts refined white oil, 4 parts fresh white oil, 0.7 parts stability modifier, and 0.3 parts anti-yellowing agent. The fresh white oil is 100# industrial grade white oil with a purity ≥99.99% and a kinematic viscosity of 78 mm² / s. The stability modifier is a mixture of calcium stearate and zinc stearate at a mass ratio of 3:2, both with a purity ≥98%. The anti-yellowing agent is a mixture of triphenyl phosphite and UV-531 at a mass ratio of 4:1, with triphenyl phosphite and UV-531 having a purity ≥99% and ≥99% respectively.

[0086] High-strength polyethylene is ultra-high molecular weight polyethylene with a weight-average relative molecular weight of 3 million, a particle size of 150 mesh, and a bulk density of 0.4 g / cm³; crude white oil is 100# industrial grade white oil with an initial kinematic viscosity of 78 mm² / s and a purity of ≥99.5%. Contaminants include UHMWPE micro powder, equipment corrosion particles, moisture, trace extractants, oxidation products, and color substances.

[0087] The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system also includes process monitoring and parameter adjustment steps. Specifically, temperature sensors, pressure sensors, and liquid level sensors are installed on the crude white oil storage tank, composite adsorption tank, chromatography adsorption tower, vacuum distillation tower, refined white oil blending tank, and refined white oil storage tank to monitor the temperature, pressure, and liquid level in each device in real time.

[0088] Sampling points were set up after pretreatment, primary composite adsorption, secondary chromatographic adsorption, vacuum distillation, and blending to meet standards. Samples were taken regularly to test the indicators of white oil, including purity, kinematic viscosity, color, transmittance, moisture content, extractant residue, and mechanical impurity content.

[0089] Based on monitoring data and test results, the operating parameters of each step are adjusted in real time, including heating temperature, stirring speed, adsorption time, distillation temperature and nitrogen flow rate, to ensure stable operation of the process and that the white oil purification effect and reuse quality meet the standards.

[0090] At the same time, a process operation log should be established to record the operating parameters, test results and equipment operating status of each step.

[0091] The processes obtained in Examples 1 to 5 are compared with the conventional process, as shown in the table below:

[0092] Comparative Example Example 1 Example 2 Example 3 Example 4 Example 5 White oil recycling rate (%) 82.5 96.5 96.1 95.9 95.8 95.5 Purity of white oil after purification (%) 99.98 99.99 99.99 99.99 99.99 99.99 Kinematic viscosity of white oil (mm² / s) 75 79 78 78 77 77 White oil transmittance (%) 82 86 85 84 84 83 Moisture content (%) 0.16 0.02 0.02 0.03 0.03 0.04 Extractant residue (ppm) 40 6 6 7 7 8 Adsorbent loss reduced (%) 28 36 36 35 35 34 Extractant recovery rate (%) 91.7 98.7 98.6 98.6 98.5 98.5 Overall energy consumption reduced (%) 14 33 33 32 32 31 Number of cycles to achieve stability (times) ≤5 ≥10 ≥10 ≥10 ≥10 ≥10

[0093] The comparative example uses Chinese patent document with application number 202411725381.X.

[0094] Testing items Standard Number White oil recycling rate Industry-standard methods Purity of white oil after purification GB / T11133-2020 Kinematic viscosity of white oil GB / T265-2021 White oil color GB / T3555-2022 White oil transmittance ASTM D1544-2018 Moisture content GB / T11133-2020, ASTM D6304-20 Extractant residue GB / T30519-2014 Reduced adsorbent loss Industry-standard methods Extractant recovery rate Industry-standard methods Overall energy consumption reduced GB / T2589-2020 Cycle stability count Industry-standard methods

[0095] All tests are conducted under the environmental conditions specified in the standard: temperature 23℃±2℃, humidity 50%±5%. Testing instruments must be calibrated in advance to ensure that the testing accuracy meets the standard requirements. The instrument calibration cycle should not exceed 12 months. Sample collection must follow GB / T4756 "Manual Sampling Method for Petroleum Liquids." Each test item must be tested in parallel at least three times, and the average value is taken as the final test result. The parallel testing error must meet the precision requirements of the corresponding standard. If some test items do not have clear national / international standards, industry-standard testing methods are used to ensure that the testing methods are scientific, repeatable, and that the test data is traceable and matches the process parameters and performance indicators of this invention. All referenced standards in this standard are current valid versions. If the standard is updated, the latest version shall be followed to ensure the standardization and timeliness of the testing work.

[0096] As can be seen from the table above, the process obtained by the present invention has significantly improved purification index, recycling rate, reuse stability, environmental protection and energy saving effect, and implementation one is the best embodiment.

[0097] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for deep purification and recycling of white oil in a high-strength polyethylene gel spinning system, characterized in that, Includes the following steps: S1: Crude white oil collection and pretreatment. Crude white oil generated from the high-strength polyethylene gel spinning extraction section, centrifugal degreasing, and drying tail gas condensation is collected and deposited into a crude white oil storage tank. Pretreatment aids are added to the crude white oil. Under a nitrogen protective atmosphere, the oil is heated at 60-80℃ for 30-60 minutes to break the emulsion, with the stirring speed controlled at 150-200 r / min, to reduce the viscosity of the white oil and disrupt the oil-in-water / water-in-oil emulsion system. Subsequently, free water is separated by a high-efficiency oil-water separator. The free water is allowed to settle and filtered before being discharged in compliance with standards. Then, the oil is passed through a vacuum flash evaporator at a vacuum degree of -0.08 to -0.09 MPa and a temperature of 65-75℃ to remove dissolved water and low-boiling-point extractant from the white oil. The low-boiling-point extractant is condensed and recovered and recycled for use in the spinning extraction section. Finally, the oil is pre-filtered by a 50-100μm basket filter to remove large particulate mechanical impurities, including UHMWPE micro powder, equipment corrosion particles, and bleaching clay powder, to obtain pretreated white oil. S2: Primary composite adsorption purification. Pretreated white oil is introduced into a composite adsorption tank. Under a nitrogen protective atmosphere, the temperature is raised to 80-90℃, and the stirring speed is controlled at 120-150 r / min. Customized composite adsorbent is added at a ratio of 0.8-2.0% of the white oil mass. The mixture is stirred for 1 hour and then kept at 82℃ for adsorption. This allows the composite adsorbent to fully adsorb the colloids, oxidation products, some pigments, and trace polar impurities in the white oil. After adsorption is complete, stirring is stopped, and the mixture is allowed to settle for 12 minutes. Subsequently, the mixture is filtered through a plate and frame filter press at a pressure of 0.4 MPa, a temperature of 81℃, and a filtration rate of 7 m³ / (m²·h). The filtrate is collected, and the filter cake is a mixture of adsorbent and impurities. After harmless treatment, the mixture is disposed of. During the adsorption process, the nitrogen flow rate is 0.011 m³ / h to ensure an oxygen-free environment, prevent white oil oxidation, and avoid adsorbent oxidation and inactivation. S3: Secondary chromatography adsorption purification. The filtrate is passed into a chromatography adsorption tower, which is filled with a composite adsorption bed. The composite adsorption bed consists of a silica gel layer, an activated carbon layer, and a molecular sieve layer from top to bottom. Each layer is separated by a quartz sand pad. The flow rate of the white oil is controlled at 1 BV / h, the adsorption temperature is 40℃, and the adsorption pressure is 0.2MPa. Deep adsorption is carried out under a nitrogen protective atmosphere. After adsorption, the white oil is precisely filtered through a series of 10μm→5μm→1μm→0.5μm security filters to remove adsorbent powder and ensure that the white oil is free of mechanical impurities. S4: Three-stage vacuum distillation purification. Distillation-modifying additives are added to the finely filtered white oil and stirred for 25 minutes at 100–120 r / min to ensure uniform dispersion. The mixture is then introduced into a vacuum distillation column, with the vacuum level controlled at -0.095 MPa, reboiler temperature at 180–220℃, and top temperature at 120–150℃. The column reboiler heating rate is 3–5℃ / min, and the top reflux ratio is 4:

1. High-purity nitrogen (≥99.99%) is introduced for stripping during the distillation process. The flow rate is 0.1–0.2 m³ / h, which enhances the removal of residual VOC extractant and odor. Light components are collected at the top of the column, condensed and recovered. The extractant is recycled for use in the spinning extraction section. Light component impurities are incinerated. Refined white oil is collected at the bottom of the column. After being cooled to 60–70°C by a cooler, the refined white oil is sent to the intermediate storage tank. The distillation column is filled with high-efficiency distillation packing material, which is stainless steel corrugated packing material, model 250Y, added at 17% of the distillation column volume. The distillation yield is ≥98%. Nitrogen protection is used throughout the distillation process. S5: Refined white oil formulation and recycling: The collected refined white oil is cooled to 40-50℃ and sent to the refined white oil blending tank. Under the condition of stirring speed of 80-100r / min, fresh white oil, stability regulator and anti-yellowing agent are added in sequence and stirred for 30-40 minutes to ensure that the components are uniformly mixed. Then the white oil indicators are tested: purity ≥99.98%, kinematic viscosity 75-80mm² / s, color ≤1, light transmittance ≥80%, no mechanical impurities, no odor. After meeting the standards, it is pumped into the refined white oil storage tank and stored in a nitrogen-sealed container. The nitrogen pressure is maintained at 0.02-0.03MPa to prevent the white oil from oxidizing. Finally, the refined white oil is sent to the high-strength polyethylene gel spinning dissolution section and recycled for UHMWPE powder dissolution to achieve closed-loop circulation. During the blending process, the nitrogen flow rate is 0.03-0.05m³ / h to ensure that the blending process is in an oxygen-free environment.

2. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, In step S1, the pretreatment aid, based on the mass of crude white oil, includes 0.1–0.3% of demulsifier SP-169, 0.05–0.15% of antioxidant 1010, and the remainder is deionized water. The ratio of the pretreatment aid to crude white oil is 1:

60. Demulsifier SP-169 is a polyoxyethylene-polyoxypropylene block copolymer, and antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. During the pretreatment process, the nitrogen gas flow rate is 0.07 m³ / h.

3. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, In step S2, the customized composite adsorbent, by weight, comprises 69 parts activated clay, 15 parts modified activated carbon, 10 parts molecular sieve, 4 parts graphene oxide solution, and 2 parts cationic surfactant; the activated clay is natural bentonite activated at 300-350℃, with a specific surface area ≥200m² / g and an adsorption capacity ≥150mg / g; the modified activated carbon, by weight, comprises 8% activated carbon, 1% 3-chloro-2-hydroxypropyltrimethylammonium chloride, 9% tannic acid, 42% 3wt% hydroxylamine hydrochloride solution, and 40% 10wt% sodium hydroxide solution; The molecular sieve is 4A molecular sieve with a particle size of 1-3 mm; the graphene oxide solution concentration is 20 wt%, prepared by the Hummers method, and the graphene oxide sheet thickness is 1 nm; the cationic surfactant is octadecyltrimethylammonium chloride with a purity ≥98%; the preparation method of the customized composite adsorbent is as follows: first, activated carbon, oxidant and 3-chloro-2-hydroxypropyltrimethylammonium chloride are mixed and refluxed at 75°C for 2 hours. The oxidant is selected from nitric acid and hydrogen peroxide, and the mass ratio of oxidant to activated carbon is 1:

2. After reflux, tannic acid is added and ultrasonically dissolved for 70 minutes with an ultrasonic power of 350 W and an ultrasonic frequency of 27 kHz. Then, hydroxylamine hydrochloride solution and sodium hydroxide solution are added and ultrasonically dispersed for 50 minutes. The pH of the reaction system is adjusted to 7.0-7.5, filtered and washed until neutral, and dried at 107°C for 2 hours to obtain modified activated carbon.

4. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 3, characterized in that, In step S2, activated clay, modified activated carbon, and molecular sieve are mixed, and graphene oxide solution and cationic surfactant are added. The mixture is ultrasonically dispersed for 35 minutes at an ultrasonic power of 350W and an ultrasonic frequency of 27kHz. Subsequently, it is calcined at 430℃ for 2 hours at a calcination heating rate of 6℃ / min. After cooling to room temperature, it is pulverized to 90 mesh, sieved, and sealed for storage to obtain the customized composite adsorbent.

5. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, In S3, the silica gel is modified silica gel, and its formula is: 93 parts silica gel, 4 parts γ-aminopropyltriethoxysilane and 3 parts deionized water. The preparation method of modified silica gel is as follows: the silica gel is mixed with γ-aminopropyltriethoxysilane and deionized water, and hydrolyzed at a temperature of 60-70°C for 2 hours. After the hydrolysis reaction, it is cured at a temperature of 120-150°C for 3 hours. After cooling to room temperature, it is pulverized to 70 mesh, sieved and used for later use. The activated carbon layer is modified activated carbon, and the molecular sieve layer is 4A molecular sieve.

6. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, In step S4, the components of the distillation-modified additive include antioxidant B225, deodorizing agent, and distillation aid. Antioxidant B225 is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:

1. The deodorizing agent is a mixture of vanillin and citral in a mass ratio of 2:1, both with a purity ≥99%. The distillation aid is dibutyl phthalate with a purity ≥99.5%.

7. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, In S5, the recycled formulation is as follows: 95 parts refined white oil, 4 parts fresh white oil, 0.7 parts stability modifier, and 0.3 parts anti-yellowing agent. The fresh white oil is 75# to 100# industrial grade white oil with a purity ≥99.99% and a kinematic viscosity of 75 to 80 mm² / s. The stability modifier is a mixture of calcium stearate and zinc stearate at a mass ratio of 3:2, both with a purity ≥98%. The anti-yellowing agent is a mixture of triphenyl phosphite and UV-531 at a mass ratio of 4:1, with triphenyl phosphite having a purity ≥99% and UV-531 having a purity ≥99%.

8. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, The high-strength polyethylene is ultra-high molecular weight polyethylene with a weight-average relative molecular weight of 1 million to 5 million, a particle size of 100 to 200 mesh, and a bulk density of 0.3 to 0.5 g / cm³; the crude white oil is 75# to 100# industrial grade white oil with an initial kinematic viscosity of 75 to 80 mm² / s and a purity of ≥99.5%. The contaminants include UHMWPE micro powder, equipment corrosion particles, moisture, trace extractants, oxidation products, and color substances.

9. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, In step S2, the filtration pressure of the plate and frame filter press is 0.3-0.5 MPa, the filtration temperature is 75-85℃, the filtration speed is 5-8 m³ / (m²·h), and the filter cloth is made of polypropylene with a pore size of 0.1-0.2 μm, which can effectively trap adsorbent powder and impurities.

10. The process for deep purification and recycling of white oil in the high-strength polyethylene gel spinning system according to claim 1, characterized in that, The high-strength polyethylene gel spinning system white oil deep purification and recycling process also includes process monitoring and parameter adjustment steps, specifically: temperature sensors, pressure sensors, and liquid level sensors are respectively installed on the crude white oil storage tank, composite adsorption tank, chromatography adsorption tower, vacuum distillation tower, refined white oil blending tank, and refined white oil storage tank to monitor the temperature, pressure, and liquid level in each device in real time. Sampling points were set up after pretreatment, primary composite adsorption, secondary chromatographic adsorption, vacuum distillation, and blending to meet standards. Samples were taken regularly to test the indicators of white oil, including purity, kinematic viscosity, color, transmittance, moisture content, extractant residue, and mechanical impurity content. Based on monitoring data and test results, the operating parameters of each step are adjusted in real time, including heating temperature, stirring speed, adsorption time, distillation temperature and nitrogen flow rate, to ensure stable operation of the process and that the white oil purification effect and reuse quality meet the standards. At the same time, a process operation log should be established to record the operating parameters, test results and equipment operating status of each step.

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