A method for regenerating waste lubricating oil

Abstract

The present invention discloses a method for regenerating waste lubricating oil, and relates to the technical field of waste lubricating oil regeneration. The present invention utilizes modified attapulgite to perform adsorption decolorization and heavy metal removal of waste lubricating oil, so that the doped heavy metal salt forms inorganic matter attached to the surface of attapulgite, and the metal ions in the waste lubricating oil can be efficiently removed, greatly reducing the metal content in the waste lubricating oil; the present invention subjects the pretreated waste lubricating oil to two refining treatments, and adopts a high-temperature nitrogen spraying method to the waste lubricating oil to accelerate the vaporization reaction of the impurity components and improve the properties of the regenerated oil products, and then performs a second hydrogenation refining treatment to hydrogenate and saturate non-ideal components such as nitrogen-containing compounds and sulfur-containing compounds, and vaporize and remove them at high temperature; the present invention combines the pretreatment process with the hydrogenation post-treatment process to improve the properties of the regenerated oil products, and the process flow is simple, which is superior to the multi-tower equipment process of the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of waste lubricating oil regeneration, and in particular to a waste lubricating oil regeneration treatment method. Background Art

[0002] With the development of the automobile industry, the demand for motor vehicle lubricants continues to grow. The average annual growth rate of lubricant production in my country is 8.4%, far higher than the world's 1.4%. With the continuous expansion of lubricant demand, the pollution of waste lubricants to the environment is also worrying. Waste lubricants contain a large number of substances that are harmful to the human body, such as carcinogenic polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and various heavy metal ultrafine particles. Direct discharge will cause resource waste, water and soil resource pollution, and ecological environment damage. In particular, waste lubricants have polluted groundwater for as long as 100 years. A small amount of waste lubricants will hinder plant growth and poison aquatic organisms. At present, waste lubricants are disposed of by direct incineration and waste lubricant regeneration. The smoke generated by direct incineration contains a large amount of toxic substances such as dioxins, sulfur and phosphorus organic compounds, which seriously pollute the air. From the perspective of environmental protection, resource utilization and economy, it is a suitable choice to reuse waste lubricants after appropriate process treatment to remove deteriorated components and foreign pollutants.

[0003] During the use of lubricating oil, due to mechanical friction or operation, impurities such as rust, metal wear powder, ash powder and other incomplete combustion are generated, and the oil itself deteriorates, generating organic acid colloid and asphalt-like substances. At present, the market for the comprehensive utilization of waste lubricating oil regeneration lacks the intervention of high-end technology. Crude oil refining and small oil refining are prevalent. Due to backward technology, low product yield and serious pollution, it has brought about resource waste and secondary environmental pollution again, causing chaos in the domestic oil market. Fake oil and substandard oil products have flowed into the oil market in large quantities, bringing serious safety hazards to various oil-using equipment. In recent years, the country has continuously issued policies and regulations to guide high-end technology to intervene in the waste lubricating oil regeneration market, and support and support high-end technology to carry out waste oil regeneration projects.

[0004] Therefore, the introduction of high-quality waste lubricating oil recycling technology has important economic and social benefits for solving practical problems such as lubricating oil recycling and energy shortage in my country, promoting the comprehensive recycling of national resources, developing a circular economy, forming a closed-loop industrial chain, combating counterfeit and inferior oil products, purifying the oil market, reducing environmental pollution, and promoting the sustainable development of the ecological environment. Summary of the invention

[0005] The purpose of the present invention is to provide a method for regenerating waste lubricating oil to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solution: a method for regenerating waste lubricating oil, comprising the following steps:

[0007] (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the pH value of the solution was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added until the mass concentration was 3-7%, and after hydrolysis for 30 minutes, attapulgite was added, wet-grinded at 80°C for 20-35 minutes, filtered, and dried to obtain pretreated attapulgite;

[0008] (2) The pretreated attapulgite was dispersed in anhydrous ethanol, and a 15% sodium hydroxide solution was added at 40-60°C, and ultrasonic treatment was performed for 30-60 min. Then, 3-7 times the mass of chloroacetic acid of the pretreated attapulgite was added, and ultrasonic treatment was performed at 60°C for 2-3.5 h. Then, the solution was cooled to room temperature, and glacial acetic acid was added until the pH value of the solution was 7. The solution was filtered, and a 95% ethanol aqueous solution was added. The solution was centrifuged at 3000 rpm for 10 min. The solid was taken, and it was rinsed with distilled water for 3 times, and dried to obtain the modified attapulgite.

[0009] (3) Pump the waste lubricating oil into a sedimentation tank, stir at 100-200 rpm for 30 min, heat and let it settle for 10-12 h to remove large particle size impurities and some water;

[0010] (4) adding 0.01 to 0.03 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3), stirring at 70 to 80° C. and 100 rpm for 30 to 40 min, and filtering to remove the modified attapulgite;

[0011] (5) Preheat the furnace at 130~150m 3 / h nitrogen is introduced for 3-5 min, and the flow rate is increased to 200-250m 3 / h, at the same time, the waste lubricating oil obtained in step (4) is pumped into a heating furnace equipped with a nozzle and sprayed relative to nitrogen, the spraying pressure is 0.9~1.1 bar, and the temperature is 25°C. After all the waste lubricating oil is sprayed, a catalyst with a mass of 0.01~0.1 times that of the waste lubricating oil obtained in step (4) is added, wherein the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 100~220mL / min, and then the temperature is raised to 320~400°C at 8~15°C / min, and hydrogenation is performed at a pressure of 5~15MPa for 90~120min.

[0012] Furthermore, the amount of attapulgite added in step (1) is 1g:20mL~1g:30mL.

[0013] Furthermore, the grinding rate in step (1) is 0.262-1.572 m / s.

[0014] Furthermore, the drying temperature in steps (1) and (2) is 60° C. and the drying time is 12 h.

[0015] Furthermore, in step (2), the solid-liquid ratio of the pretreated attapulgite and anhydrous ethanol is 0.1 g:10 mL to 0.3 g:20 mL, the solid-liquid ratio of the pretreated attapulgite and sodium hydroxide solution is 0.1 g:6 mL, and the solid-liquid ratio of the pretreated attapulgite and ethanol aqueous solution is 0.1 g:4 mL.

[0016] Furthermore, the ultrasonic power in step (2) is 400-600W.

[0017] Furthermore, the heating temperature in step (3) is 60-80°C.

[0018] Furthermore, the filtration pressure in step (4) is 65500~67000Pa.

[0019] Furthermore, the nitrogen temperature in step (5) is 170-190°C.

[0020] Furthermore, in step (5), the nozzle and the gas inlet are placed horizontally opposite to each other.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] The present invention utilizes attapulgite and N-(3-triethoxysilylpropyl)-4-hydroxybutyramide to blend and grind for modification. N-(3-triethoxysilylpropyl)-4-hydroxybutyramide is grafted on the surface of attapulgite to improve the hydrophobicity of attapulgite and effectively disperse in waste lubricating oil, thereby better exerting the decolorization effect of attapulgite. Meanwhile, the attapulgite can be changed from a flaky structure to a loose porous structure, which is beneficial to the adsorption and decolorization of waste lubricating oil. Then, the hydroxyl group is carboxymethylated so that the modified attapulgite can react with the heavy metal salt in the waste lubricating oil to form inorganic substances attached to the surface of the attapulgite, so that the metal ions in the waste lubricating oil can be efficiently removed, and the metal content in the waste lubricating oil can be greatly reduced. After centrifugation, solid impurities such as adsorbent and asphalt are removed. In addition, the adsorbent used in the present invention can be acid-washed and reused for a second time.

[0023] The present invention subjects the pretreated waste lubricating oil to two refining treatments, and adopts a high-temperature nitrogen spraying method to the waste lubricating oil, so that light hydrocarbons, water and gasoline impurities in the waste lubricating oil are vaporized and removed, and the base oils are accumulated at the bottom of the tower due to gravity, so as to carry out a second refining treatment. In the spraying process, the present invention adopts a spraying form to form droplets with a smaller particle size of the waste lubricating oil, which can fully contact with the high-temperature gas, thereby accelerating the vaporization reaction of the impurity components and improving the properties of the regenerated oil products. Then, a second refining treatment is carried out, and after the gas is completely removed, hydrogen is introduced, and hydrogenation refining is carried out under the action of a catalyst, so that non-ideal components such as nitrogen-containing compounds and sulfur-containing compounds are hydrogenated and saturated, and vaporized and removed at high temperature. The present invention combines the pretreatment process with the hydrogenation post-treatment process, improves the properties of the regenerated oil products, and can be used as lubricating oil base oil again, and the process flow is simple, which is superior to the multi-tower equipment process of the prior art, has strong flexibility, a wide range of application, and does not cause any pollution to the environment. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the solution pH was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added to a mass concentration of 3%, and after hydrolysis for 30 minutes, attapulgite was added under stirring at a material-liquid ratio of 1g:20mL, and wet grinding was performed at a grinding rate of 0.262m / s and 80℃ for 20 minutes, and then filtered and dried at 60℃ for 12 hours to obtain pretreated attapulgite;

[0027] (2) The pretreated attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 0.1 g:10 mL, and a 15% sodium hydroxide solution was added at 40°C, and the solid-liquid ratio of the pretreated attapulgite and the sodium hydroxide solution was 0.1 g:6 mL. Ultrasound was performed at 400 W for 30 min, and chloroacetic acid was added in an amount three times the mass of the pretreated attapulgite. Ultrasound was continued at 60°C for 2 h, and then cooled to room temperature. Glacial acetic acid was added until the solution pH was 7, and filtered. A 95% ethanol aqueous solution was added, and the solid-liquid ratio of the pretreated attapulgite and the ethanol aqueous solution was 0.1 g:4 mL. Centrifuged at 3000 rpm for 10 min, the solid was taken, rinsed with distilled water three times, and dried at 60°C for 12 h to obtain modified attapulgite.

[0028] (3) Pump the waste lubricating oil into a sedimentation tank, stir at 100 rpm for 30 min, heat to 60 °C, and let it settle for 10 h to remove large particle size impurities and some water;

[0029] (4) adding 0.01 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3) of modified attapulgite, stirring at 70°C and 100 rpm for 30 min, and filtering under a pressure of 65500 Pa to remove the modified attapulgite;

[0030] (5) Preheat the furnace at 130m 3 / h to introduce nitrogen at 170℃ for 3 minutes, and increase the flow rate to 200m 3 / h, at the same time, the waste lubricating oil obtained in step (4) is pumped into a heating furnace equipped with a nozzle and sprayed relative to nitrogen. The oil spraying pressure is 0.9 bar and the temperature is 25°C. The nozzle and the gas inlet are placed horizontally opposite to each other. After the waste lubricating oil is completely sprayed, a catalyst with a mass of 0.01 times that of the waste lubricating oil obtained in step (4) is added, wherein the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 100 mL / min, and then the temperature is increased to 320°C at 8°C / min. Hydrogenation is performed at a pressure of 5 MPa for 90 min to finally obtain a base oil fraction with a yield of 89.1%.

[0031] Example 2

[0032] (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the solution pH was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added to a mass concentration of 5%, and after hydrolysis for 30 minutes, attapulgite was added under stirring at a material-liquid ratio of 1g:25mL, and wet grinding was performed at a grinding rate of 1.278m / s and 80℃ for 28 minutes, and then filtered and dried at 60℃ for 12 hours to obtain pretreated attapulgite;

[0033] (2) The pretreated attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 0.2 g:15 mL, and a 15% sodium hydroxide solution was added at 50°C, and the solid-liquid ratio of the pretreated attapulgite and the sodium hydroxide solution was 0.1 g:6 mL. Ultrasound was performed at 500 W for 45 min, and chloroacetic acid was added in an amount 5 times the mass of the pretreated attapulgite. Ultrasound was continued at 60°C for 3 h, and then cooled to room temperature. Glacial acetic acid was added until the solution pH was 7, and filtered. A 95% ethanol aqueous solution was added, and the solid-liquid ratio of the pretreated attapulgite and the ethanol aqueous solution was 0.1 g:4 mL. Centrifuged at 3000 rpm for 10 min, the solid was taken, rinsed with distilled water 3 times, and dried at 60°C for 12 h to obtain the modified attapulgite.

[0034] (3) Pump the waste lubricating oil into a sedimentation tank, stir at 150 rpm for 30 min, heat to 70 °C, and let it settle for 11 h to remove large particle size impurities and some water;

[0035] (4) adding 0.02 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3) of modified attapulgite, stirring at 75°C and 100 rpm for 35 min, and filtering under a pressure of 66850 Pa to remove the modified attapulgite;

[0036] (5) Preheat the furnace at 140m 3 / h to introduce nitrogen at 180℃ for 4 minutes, and increase the flow rate to 225m 3 / h, at the same time, the waste lubricating oil obtained in step (4) is pumped into a heating furnace equipped with a nozzle and sprayed relative to nitrogen. The oil spraying pressure is 1.0 bar and the temperature is 25°C. The nozzle and the gas inlet are placed horizontally opposite to each other. After the waste lubricating oil is completely sprayed, a catalyst with a mass of 0.06 times that of the waste lubricating oil obtained in step (4) is added, wherein the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 160 mL / min, and then the temperature is increased to 360°C at 10°C / min. Hydrogenation refining is carried out at a pressure of 10 MPa for 105 min to finally obtain a base oil fraction with a yield of 89.3%.

[0037] Example 3

[0038] (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the solution pH was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added to a mass concentration of 7%, and after hydrolysis for 30 minutes, attapulgite was added under stirring at a material-liquid ratio of 1g:30mL, and wet grinding was performed at a grinding rate of 1.572m / s and 80℃ for 35 minutes, and then filtered and dried at 60℃ for 12 hours to obtain pretreated attapulgite;

[0039] (2) The pretreated attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 0.3 g:20 mL, and a 15% sodium hydroxide solution was added at 60°C, and the solid-liquid ratio of the pretreated attapulgite and the sodium hydroxide solution was 0.1 g:6 mL. Ultrasound was performed at 600 W for 60 min, and chloroacetic acid 7 times the mass of the pretreated attapulgite was added. Ultrasound was continued at 60°C for 3.5 h, and then cooled to room temperature. Glacial acetic acid was added until the solution pH was 7, and filtered. A 95% ethanol aqueous solution was added, and the solid-liquid ratio of the pretreated attapulgite and the ethanol aqueous solution was 0.1 g:4 mL. Centrifuged at 3000 rpm for 10 min, the solid was taken, rinsed with distilled water 3 times, and dried at 60°C for 12 h to obtain modified attapulgite.

[0040] (3) Pump the waste lubricating oil into a sedimentation tank, stir at 200 rpm for 30 min, heat to 80 °C, and let it settle for 12 h to remove large particle size impurities and some water;

[0041] (4) adding 0.03 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3) of modified attapulgite, stirring at 80° C. and 100 rpm for 40 min, and filtering under a pressure of 67000 Pa to remove the modified attapulgite;

[0042] (5) Preheat the furnace at 150m 3 / h to introduce nitrogen at 190℃ for 5 min, and increase the flow rate to 250m 3 / h, at the same time, the waste lubricating oil obtained in step (4) is pumped into a heating furnace equipped with a nozzle and sprayed relative to nitrogen. The oil spraying pressure is 1.1 bar and the temperature is 25°C. The nozzle and the gas inlet are placed horizontally opposite to each other. After the waste lubricating oil is completely sprayed, a catalyst with a mass of 0.1 times that of the waste lubricating oil obtained in step (4) is added, wherein the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 220 mL / min, and then the temperature is increased to 400°C at 15°C / min. Hydrogenation refining is carried out at a pressure of 15 MPa for 120 min to finally obtain a base oil fraction with a yield of 89.22%.

[0043] Comparative Example 1

[0044] (1) Pump the waste lubricating oil into a sedimentation tank, stir at 150 rpm for 30 min, heat to 70 °C, and let it settle for 11 h to remove large particle size impurities and some water;

[0045] (2) adding attapulgite in an amount of 0.02 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (1), stirring at 75° C. and 100 rpm for 35 min, and filtering under a pressure of 66850 Pa to remove the modified attapulgite;

[0046] (3) Preheat the furnace at 140m 3 / h to introduce nitrogen at 180℃ for 4 minutes, and increase the flow rate to 225m 3 / h, at the same time, the waste lubricating oil obtained in step (2) is pumped into a heating furnace equipped with a nozzle and sprayed relative to nitrogen. The oil spraying pressure is 1.0 bar and the temperature is 25°C. The nozzle and the gas inlet are placed horizontally opposite to each other. After the waste lubricating oil is completely sprayed, a catalyst with a mass of 0.06 times that of the waste lubricating oil obtained in step (2) is added, wherein the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 160 mL / min, and then the temperature is raised to 360°C at 10°C / min, and hydrogenation is performed at a pressure of 10 MPa for 105 min.

[0047] Comparative Example 2

[0048] (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the solution pH was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added to a mass concentration of 5%, and after hydrolysis for 30 minutes, attapulgite was added under stirring at a material-liquid ratio of 1g:25mL, and wet grinding was performed at a grinding rate of 1.278m / s and 80℃ for 28 minutes, and then filtered and dried at 60℃ for 12 hours to obtain pretreated attapulgite;

[0049] (2) The pretreated attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 0.2 g:15 mL, and a 15% sodium hydroxide solution was added at 50°C, and the solid-liquid ratio of the pretreated attapulgite and the sodium hydroxide solution was 0.1 g:6 mL. Ultrasound was performed at 500 W for 45 min, and chloroacetic acid was added in an amount 5 times the mass of the pretreated attapulgite. Ultrasound was continued at 60°C for 3 h, and then cooled to room temperature. Glacial acetic acid was added until the solution pH was 7, and filtered. A 95% ethanol aqueous solution was added, and the solid-liquid ratio of the pretreated attapulgite and the ethanol aqueous solution was 0.1 g:4 mL. Centrifuged at 3000 rpm for 10 min, the solid was taken, rinsed with distilled water 3 times, and dried at 60°C for 12 h to obtain the modified attapulgite.

[0050] (3) Pump the waste lubricating oil into a sedimentation tank, stir at 150 rpm for 30 min, heat to 70 °C, and let it settle for 11 h to remove large particle size impurities and some water;

[0051] (4) adding 0.02 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3) of modified attapulgite, stirring at 75°C and 100 rpm for 35 min, and filtering under a pressure of 66850 Pa to remove the modified attapulgite;

[0052] (5) The waste lubricating oil obtained in step (4) is pumped into a heating furnace at 225 m 3 / h nitrogen is introduced, the temperature is raised to 180°C, heated for 1.5 hours, and naturally cooled to room temperature, and then 0.06 times the mass of the waste lubricating oil obtained in step (4) is added with a catalyst, the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 160 mL / min, and then the temperature is raised to 360°C at 10°C / min, and hydrogenation is performed at a pressure of 10 MPa for 105 minutes.

[0053] Effect example

[0054] The performance analysis results of Examples 1 to 3 of the present invention and Comparative Examples 1 and 2 are given in Table 1 below.

[0055] Table 1

[0056]

[0057] The present invention utilizes modified attapulgite to react with heavy metal salts in waste lubricating oil to form inorganic substances attached to the surface of the attapulgite, which can efficiently remove metal ions in the waste lubricating oil and greatly reduce the metal content in the waste lubricating oil. The present invention subjects the pretreated waste lubricating oil to two refining treatments in the form of spraying to accelerate the vaporization reaction of impurity components and improve the properties of the regenerated oil. Hydrogenation refining is then performed to hydrogenate and saturate non-ideal components such as nitrogen-containing compounds and sulfur-containing compounds, and vaporize and remove them at high temperature. The present invention combines the pretreatment process with the hydrogenation post-treatment process to improve the properties of the regenerated oil, which can be used as a lubricating oil base oil again. The process flow is simple, which is superior to the multi-tower equipment process in the prior art, has strong flexibility, a wide range of applications, and does not cause any pollution to the environment.

[0058] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for regenerating waste lubricating oil, characterized in that: The steps are: (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the solution pH was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added to a mass concentration of 5%, and after hydrolysis for 30 minutes, attapulgite was added under stirring at a material-liquid ratio of 1g:25mL, and wet grinding was performed at a grinding rate of 1.278m / s and 80℃ for 28 minutes, and then filtered and dried at 60℃ for 12 hours to obtain pretreated attapulgite; (2) The pretreated attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 0.2 g:15 mL, and a 15% sodium hydroxide solution was added at 50°C, and the solid-liquid ratio of the pretreated attapulgite and the sodium hydroxide solution was 0.1 g:6 mL. Ultrasound was performed at 500 W for 45 min, and chloroacetic acid was added in an amount 5 times the mass of the pretreated attapulgite. Ultrasound was continued at 60°C for 3 h, and then cooled to room temperature. Glacial acetic acid was added until the solution pH was 7, and filtered. A 95% ethanol aqueous solution was added, and the solid-liquid ratio of the pretreated attapulgite and the ethanol aqueous solution was 0.1 g:4 mL. Centrifuged at 3000 rpm for 10 min, the solid was taken, rinsed with distilled water 3 times, and dried at 60°C for 12 h to obtain the modified attapulgite. (3) Pump the waste lubricating oil into a sedimentation tank, stir at 150 rpm for 30 min, heat to 70 °C, and let it settle for 11 h to remove large particle size impurities and some water; (4) adding 0.02 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3) of modified attapulgite, stirring at 75°C and 100 rpm for 35 min, and filtering under a pressure of 66850 Pa to remove the modified attapulgite; (5) Preheat the furnace at 140m 3 / h to introduce nitrogen at 180℃ for 4 minutes, and increase the flow rate to 225m 3 / h, at the same time, the waste lubricating oil obtained in step (4) is pumped into a heating furnace equipped with a nozzle, and sprayed relative to nitrogen, the oil spraying pressure is 1.0 bar, the temperature is 25°C, the nozzle and the gas inlet are placed horizontally opposite to each other, after the waste lubricating oil is completely sprayed, add a catalyst with a mass of 0.06 times that of the waste lubricating oil obtained in step (4), the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 160 mL / min, and then the temperature is increased to 360°C at 10°C / min, and hydrogenation is performed at a pressure of 10 MPa for 105 min, and finally a base oil fraction with a yield of 89.3% is obtained; Or its steps are: (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the solution pH was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added to a mass concentration of 3%, and after hydrolysis for 30 minutes, attapulgite was added under stirring at a material-liquid ratio of 1g:20mL, and wet grinding was performed at a grinding rate of 0.262m / s and 80℃ for 20 minutes, and then filtered and dried at 60℃ for 12 hours to obtain pretreated attapulgite; (2) The pretreated attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 0.1 g:10 mL, and a 15% sodium hydroxide solution was added at 40°C, and the solid-liquid ratio of the pretreated attapulgite and the sodium hydroxide solution was 0.1 g:6 mL. Ultrasound was performed at 400 W for 30 min, and chloroacetic acid was added in an amount three times the mass of the pretreated attapulgite. Ultrasound was continued at 60°C for 2 h, and then cooled to room temperature. Glacial acetic acid was added until the solution pH was 7, and filtered. A 95% ethanol aqueous solution was added, and the solid-liquid ratio of the pretreated attapulgite and the ethanol aqueous solution was 0.1 g:4 mL. Centrifuged at 3000 rpm for 10 min, the solid was taken, rinsed with distilled water three times, and dried at 60°C for 12 h to obtain modified attapulgite. (3) Pump the waste lubricating oil into a sedimentation tank, stir at 100 rpm for 30 min, heat to 60 °C, and let it settle for 10 h to remove large particle size impurities and some water; (4) adding 0.01 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3) of modified attapulgite, stirring at 70°C and 100 rpm for 30 min, and filtering under a pressure of 65500 Pa to remove the modified attapulgite; (5) Preheat the furnace at 130m 3 / h to introduce nitrogen at 170℃ for 3 minutes, and increase the flow rate to 200m 3 / h, at the same time, the waste lubricating oil obtained in step (4) is pumped into a heating furnace equipped with a nozzle, and sprayed relative to nitrogen, the oil spraying pressure is 0.9 bar, the temperature is 25°C, the nozzle and the gas inlet are placed horizontally opposite to each other, after the waste lubricating oil is completely sprayed, 0.01 times the mass of the waste lubricating oil obtained in step (4) is added with a catalyst, the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 100 mL / min, and then the temperature is increased to 320°C at 8°C / min, and hydrogenation is performed at a pressure of 5 MPa for 90 min to finally obtain a base oil fraction with a yield of 89.1%; Or its steps are: (1) Anhydrous ethanol and deionized water were mixed in a volume ratio of 95:5, glacial acetic acid was added until the solution pH was 3, N-(3-triethoxysilylpropyl)-4-hydroxybutyramide was added to a mass concentration of 7%, and after hydrolysis for 30 minutes, attapulgite was added under stirring at a material-liquid ratio of 1g:30mL, and wet grinding was performed at a grinding rate of 1.572m / s and 80℃ for 35 minutes, and then filtered and dried at 60℃ for 12 hours to obtain pretreated attapulgite; (2) The pretreated attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 0.3 g:20 mL, and a 15% sodium hydroxide solution was added at 60°C, and the solid-liquid ratio of the pretreated attapulgite and the sodium hydroxide solution was 0.1 g:6 mL. Ultrasound was performed at 600 W for 60 min, and chloroacetic acid 7 times the mass of the pretreated attapulgite was added. Ultrasound was continued at 60°C for 3.5 h, and then cooled to room temperature. Glacial acetic acid was added until the solution pH was 7, and filtered. A 95% ethanol aqueous solution was added, and the solid-liquid ratio of the pretreated attapulgite and the ethanol aqueous solution was 0.1 g:4 mL. Centrifuged at 3000 rpm for 10 min, the solid was taken, rinsed with distilled water 3 times, and dried at 60°C for 12 h to obtain modified attapulgite. (3) Pump the waste lubricating oil into a sedimentation tank, stir at 200 rpm for 30 min, heat to 80 °C, and let it settle for 12 h to remove large particle size impurities and some water; (4) adding 0.03 times the mass of the waste lubricating oil to the waste lubricating oil obtained in step (3) of modified attapulgite, stirring at 80° C. and 100 rpm for 40 min, and filtering under a pressure of 67000 Pa to remove the modified attapulgite; (5) Preheat the furnace at 150m 3 / h to introduce nitrogen at 190℃ for 5 min, and increase the flow rate to 250m 3 / h, at the same time, the waste lubricating oil obtained in step (4) is pumped into a heating furnace equipped with a nozzle and sprayed relative to nitrogen. The oil spraying pressure is 1.1 bar and the temperature is 25°C. The nozzle and the gas inlet are placed horizontally opposite to each other. After the waste lubricating oil is completely sprayed, a catalyst with a mass of 0.1 times that of the waste lubricating oil obtained in step (4) is added, wherein the mass ratio of iron oxide, copper oxide and nickel oxide in the catalyst is 1:2:1, hydrogen is introduced at 220 mL / min, and then the temperature is increased to 400°C at 15°C / min. Hydrogenation refining is carried out at a pressure of 15 MPa for 120 min to finally obtain a base oil fraction with a yield of 89.22%.

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