A process for recycling and reusing floating oil and waste emulsion in hot-rolled aluminum materials.

Abstract

This invention discloses a process for recycling and reusing floating oil and waste emulsion in aluminum hot rolling emulsion, comprising the following steps: secondary filtration of the mixture of floating oil and waste emulsion to obtain an oil-water mixture, followed by settling and separation to obtain oil phase 1 and water phase 1; adding a flotation agent to water phase 1, introducing air, settling, and separating to obtain oil phase 2 and water phase 2; mixing oil phase 1 and oil phase 2, heating, adding sulfuric acid while stirring, adjusting the water-soluble pH with alkali, settling, and separating to obtain regenerated lubricating oil; adding composite additives to the regenerated lubricating oil to prepare an emulsion; adding water phase 2 to the emulsion to prepare a concentrated hot rolling emulsion, thus realizing the recycling and regeneration of floating oil and waste emulsion in aluminum hot rolling emulsion. This invention fundamentally achieves resource utilization and volume reduction of waste emulsion, and the obtained regenerated hot rolling emulsion has good lubrication performance and good compatibility with existing hot rolling emulsions, fully meeting the requirements of lubrication technology in aluminum hot rolling processes.

Description

Technical Field

[0001] This invention belongs to the field of emulsion recycling and treatment, specifically relating to a process for recycling and reusing floating oil and waste emulsion in hot-rolled aluminum materials. Background Technology

[0002] Hot rolling is a common method for mass-producing aluminum materials. Aluminum billets are heated to above their recrystallization temperature and then rolled several times to obtain the desired thickness, width, and shape. The rolling emulsion plays a crucial role in cooling and lubrication during hot rolling of aluminum. It is a chemically stable oil-water mixture formulated with mineral oil as a base and various additives such as rust inhibitors, emulsifiers, defoamers, and antioxidants. During the recycling of the emulsion, on the one hand, lubricating oil precipitates from the emulsion, and machine oil leaking from the rolling mill, combined with aluminum powder generated during rolling, forms a large amount of black floating oil. This black floating oil seriously affects product quality and requires regular cleaning. On the other hand, the emulsion gradually ages and deteriorates due to contamination, oxidation, and rancidity, requiring replenishment with new emulsion, regular discharge, and periodic replacement, thus generating a large amount of waste emulsion. Black floating oil and waste emulsion are classified as HW09 hazardous waste (code 900-006-09) and must undergo strict treatment before discharge.

[0003] The composition of hot-rolled aluminum floating oil and waste emulsion is complex and the concentration of pollutants is extremely high. The oil content of waste emulsion is around 5000 mg / L, and the COD is between 5000 and 15000 mg / L. It also contains a certain concentration of impurities such as metal scrap and sludge, which are relatively stable. All of these factors pose a significant obstacle to the treatment of hot-rolled aluminum floating oil and waste emulsion to meet standards. The treatment of hot-rolled aluminum floating oil and waste emulsion has always been a difficult problem in the hot-rolled aluminum industry.

[0004] Currently, the main technologies for treating waste emulsions from hot-rolled aluminum production include chemical methods (coagulation demulsification, acid-added demulsification, heating demulsification, catalytic oxidation, electrolysis, electrocoagulation, etc.), biochemical methods, and physical methods (air flotation, adsorption, vacuum low-temperature distillation, ultrafiltration, etc.). For example, CN116253454A, "A Method for Treating Waste Emulsions," first separates the oil and water phases, then evaporates the aqueous phase at low temperature, followed by RO treatment and / or biochemical treatment. The treated water quality can reach Class A discharge standards, and the residue after aqueous phase evaporation is incinerated or pyrolyzed. Cui Huizhen, Lu Minyuan, and Hong Ke published "Oil Separation-Demulsification-Coagulation-Flotation-MVR Evaporation Process for Treating Waste Emulsions" in the September 2020 issue of *Energy Saving*, introducing an example of a 20t / d waste emulsion treatment center using the oil separation-demulsification-two-stage coagulation-flotation-MVR evaporation process to treat waste emulsions. The project involved an investment of 5 million yuan, with an operating cost of 1244 yuan / t and a COD removal rate exceeding 99%. Li Yuanchen published "Evaporation Treatment Method for Hot-Rolled Aluminum Emulsion" in Volume 45, Issue 7 of *Light Alloy Processing Technology*, introducing the workflow of the evaporation system, the working principle and characteristics of the evaporator, and summarizing the application effects of the evaporation treatment method for hot-rolled aluminum emulsion. Zhou Lianchen, Zhang Zihong, Wang Wencheng, et al. published "Analysis of the Reasons for the Failure of Electrolytic Demulsification of Hot-Rolled Aluminum Emulsion" in Volume 36, Issue 9 of *Light Alloy Processing Technology*, introducing the principle of electrolytic demulsification of hot-rolled aluminum emulsion, analyzing the reasons for the failure of electrolytic demulsification, and proposing suggestions for improving the electrolytic demulsification process.

[0005] However, existing treatment methods focus primarily on the aqueous phase treatment of waste emulsions, largely neglecting the recycling and reuse of floating oil and waste emulsions generated during hot rolling. Furthermore, most existing methods suffer from high investment costs, long process flows, large reagent consumption, susceptibility to fouling, poor treatment efficiency, large amounts of hazardous waste, high treatment costs, and poor working environments. They fail to adequately meet the combined needs of low investment, low operating costs, no secondary pollution, ease of use, long-lasting effectiveness, and recyclability, thus failing to adequately satisfy the actual needs of aluminum rolling and processing enterprises. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a process for recycling and reusing floating oil and waste emulsion from hot-rolled aluminum materials. This process, from the perspective of resource recycling and reducing waste emulsion emissions, can effectively treat the floating oil and waste emulsion generated during hot rolling of aluminum materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The present invention first provides a flotation agent, which is composed of the following components in parts by weight: 10-50 parts sodium alkylbenzene sulfonate, 20-50 parts sodium hydroxide, 5-15 parts sodium carbonate, 5-15 parts sodium propionate, and 5-30 parts light white oil.

[0009] This invention also provides a composite additive, composed of the following components in parts by weight: 1-5 parts of an oily antioxidant, 20-50 parts of oleic acid, 10-30 parts of triethanolamine, 3-15 parts of triethanolamine borate, 5-30 parts of Span, 5-30 parts of Tween, 10-30 parts of fatty alcohol polyoxyethylene ether, and 1-5 parts of a stabilizer. This composite additive possesses good emulsifying and dispersing properties, excellent lubrication properties, and highly efficient rust-preventing properties, effectively meeting the technical requirements for lubrication in the hot rolling process of aluminum materials.

[0010] More preferably, the oily antioxidant is at least one of T501, T502, and T551; and the stabilizer is at least one of ethanol, glycerol, isohexyl glycol, and propylene glycol derivatives.

[0011] This invention also provides a process for recycling and reusing floating oil and waste emulsion in hot-rolled aluminum materials, comprising the following steps:

[0012] S1. Collect the mixture of floating oil and waste emulsion in the hot-rolled aluminum emulsion, and perform secondary filtration on the mixture to obtain waste residue and oil-water mixture; let the oil-water mixture stand, and then separate the oil and water to obtain oil phase 1 and water phase 1; the waste residue is processed by pressure filtration and then outsourced.

[0013] S2. Add the flotation agent to the aqueous phase 1 obtained in step S1, introduce air for a preset time, let stand, and separate the oil phase 2 and the aqueous phase 2.

[0014] S3. Mix the oil phase 1 obtained in step S1 and the oil phase 2 obtained in step S2, heat to the set temperature, add strong acid while stirring, then continue stirring, then add alkali to adjust the water-soluble pH value to the set range, let stand, and perform solid-liquid separation to obtain regenerated lubricating oil and waste residue. The waste residue is processed by pressure filtration and then outsourced.

[0015] S4. Add the composite additive to the regenerated lubricating oil obtained in step S3 to formulate an emulsified oil;

[0016] S5. Add the aqueous phase 2 obtained in step S2 and the water to be added as needed to the emulsified oil obtained in step S4 according to the preset ratio to prepare a hot-rolled concentrated emulsion, so as to realize the recycling and reuse of floating oil and waste emulsion in the hot-rolled emulsion of aluminum.

[0017] Preferably, in step S1, the oil-water mixture is left to stand for 4 to 24 hours.

[0018] Preferably, in step S2, the amount of flotation agent added is 2.5% to 5% of the mass of aqueous phase 1.

[0019] Preferably, in step S2, the time for introducing air is 2 to 3 minutes, and the time for letting it stand is 30 to 120 minutes.

[0020] In step S2, the flotation agent is added to the aqueous phase 1, and air is introduced to allow the black aluminum powder and other solid particles present in the aqueous phase 1 to be fully separated from the aqueous phase and enter the oil phase. After standing and separation, oil phase 2 and aqueous phase 2 are obtained.

[0021] It should be noted that sodium alkylbenzene sulfonate in the flotation agent is an anionic surfactant that can increase the foam of the waste emulsion and enhance the flotation effect; sodium hydroxide, sodium carbonate and sodium propionate can adjust the pH value of the waste emulsion to achieve demulsification; light white oil has a strong adsorption effect on fine particles such as aluminum powder in the emulsion, causing the fine particles to migrate from the aqueous phase to the oil phase, thereby accelerating the suspension of fine particles such as aluminum powder to the surface in the emulsion.

[0022] Preferably, in step S3, the set temperature is 50-100℃;

[0023] Preferably, in step S3, the strong acid is at least one of sulfuric acid, hydrochloric acid, and perchloric acid.

[0024] In some specific embodiments, in step S3, the strong acid is sulfuric acid with a mass concentration of 90%-98%, and the amount added is 5% to 10% of the total volume of oil phase 1 and oil phase 2.

[0025] Preferably, in step S3, the stirring time is 30 to 120 minutes.

[0026] It should be noted that adding a strong acid to the mixture of oil phase 1 and oil phase 2 has several benefits. Firstly, the strong acid reacts chemically with the black aluminum powder in the oil, producing substances such as aluminum sulfate and aluminum chloride, which accelerates the coagulation of fine particles like aluminum powder, leading to their removal as sediment. Secondly, the strong acid can also dissolve, sulfonate, or condense oxidation products in the oil (such as gums, asphaltenes, unsaturated hydrocarbons, carboxylic acids, amino acids, naphthenic acids, phenols, and other acidic and neutral products). Most of these products enter the acid sludge and are removed with the sediment, thus achieving the goal of removing impurities and improving oil quality.

[0027] Preferably, in step S3, the alkali is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, and the water-soluble pH value is set in the range of 6 to 10.

[0028] Preferably, in step S3, the settling time is 4h to 24h.

[0029] Preferably, in step S4, the amount of the composite additive added is 15% to 25% of the mass of the regenerated lubricating oil.

[0030] It should be noted that the oleic acid, triethanolamine, and triethanolamine borate in the composite additive can improve both the lubrication and rust prevention properties of the emulsion. Oleic acid and triethanolamine can also adjust the pH value of the emulsion. Span, Tween, and fatty alcohol polyoxyethylene ether are surfactants with hydrophilic and hydrophobic groups at one end of their molecules, which can reduce the interfacial tension between the oil and water phases and play a role in solubilization and dispersion. Antioxidants can prevent the oxidation of the lubricating oil in the emulsion and extend the service life of the emulsion. Stabilizers are polar organic compounds with small molecular weights that can enhance the binding force between Span, Tween, and fatty alcohol polyoxyethylene ether and the oil and water phases, thereby improving the stability of the emulsion.

[0031] Preferably, in step S5, the ratio of the total mass of the aqueous phase 2 and the water added as needed to the mass of the emulsified oil is (1-2):1.

[0032] In some specific embodiments, during the preparation of the hot-rolled emulsion in step S5, pH adjusters, bactericides, and disodium ethylenediaminetetraacetate (EDTA) may be added as needed, depending on the operating conditions and water quality. The pH adjuster is added to adjust the pH of the emulsion to between 7 and 9. Kathon, a highly effective bactericide, can be used to inhibit the growth of bacteria and fungi and prevent emulsion spoilage. Disodium EDTA is added to chelate calcium, magnesium, and other metal ions in the water, thereby improving the water quality of the emulsion and enhancing its stability.

[0033] The beneficial effects of this invention are:

[0034] 1) This invention provides a method for treating waste emulsion, which combines filtration, flotation and emulsion regeneration processes to effectively separate oil, water and slag in waste emulsion and reprocess it into hot-rolled emulsion, thereby turning waste into treasure and recycling it, and fundamentally realizing the resource utilization and volume reduction of waste emulsion.

[0035] 2) The regenerated hot-rolling emulsion prepared by this invention has good lubrication performance and good compatibility with existing hot-rolling emulsions, fully meeting the requirements of lubrication technology for hot-rolling aluminum materials.

[0036] 3) The waste emulsion recycling process provided by this invention has the advantages of short process, strong operability, low overall cost, no secondary pollution, convenient use, long-lasting effectiveness and recyclability. The investment can be recovered in a short period of time, which is economical and suitable for promotion. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0038] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0039] Example 1

[0040] The flotation agent used in this embodiment is composed of the following parts by weight: 20 parts sodium alkylbenzene sulfonate, 50 parts sodium hydroxide, 5 parts sodium carbonate, 5 parts sodium propionate, and 20 parts light white oil.

[0041] The composite additive is composed of the following components in parts by weight: 24 parts oleic acid, 13 parts triethanolamine, 14 parts triethanolamine borate, 5 parts Tween, 11 parts Span, and 28 parts fatty alcohol polyoxyethylene ether, 3 parts oily antioxidant, and 2 parts stabilizer, wherein the oily antioxidant is T502 and the stabilizer is isohexyl glycol.

[0042] A process for recycling and reusing floating oil and waste emulsion in hot-rolled aluminum materials includes the following steps:

[0043] S1. Collect the mixture of floating oil and waste emulsion in hot-rolled aluminum material emulsion, and perform secondary filtration on the mixture to obtain waste residue and oil-water mixture; the waste residue is processed by pressure filtration and then outsourced; the oil-water mixture is allowed to stand for 4 hours, and then the oil and water are separated to obtain oil phase 1 and water phase 1, with a volume ratio of 1:1.

[0044] S2. Add the flotation agent to the aqueous phase 1, wherein the amount of flotation agent added is 5% of the mass of the aqueous phase 1, air is introduced for 2 minutes, and the mixture is allowed to stand for 60 minutes. Solid particles such as black aluminum powder form a suspension, and oil phase 2 and aqueous phase 2 are separated, wherein the volume ratio of oil phase 2 to aqueous phase 2 is 1:9.

[0045] S3. Mix oil phase 1 and oil phase 2, heat to 90°C, and slowly add 98% concentrated sulfuric acid solution while stirring. The amount of sulfuric acid solution added is 5% of the total volume of the mixture of oil phase 1 and oil phase 2. Continue stirring for 60 minutes, then add 10% sodium hydroxide solution to make the water-soluble pH value 8.2. Let stand for 12 hours, and separate the solid and liquid to obtain regenerated lubricating oil and waste residue. The waste residue is processed by pressure filtration and then outsourced.

[0046] S4. Add a composite additive to the recycled lubricating oil, wherein the mass of the composite additive is 15% of the mass of the recycled lubricating oil, and blend it into an emulsified oil.

[0047] S5. Add the aqueous phase 2 to the emulsified oil obtained in step S4 at a mass ratio of 1:1, stir thoroughly to prepare a hot-rolled concentrated emulsion.

[0048] The performance of the hot-rolled concentrated emulsion was tested, and its performance indicators are shown in Table 1. It meets the requirements of the SH / T0365-92 emulsified oil standard.

[0049] Table 1 Performance Indicators of Hot-Rolled Concentrated Emulsion

[0050]

[0051] Each ton of the mixture of floating oil and waste emulsion from the hot-rolled aluminum emulsion in step S1 can regenerate 510 kg of hot-rolled emulsion oil through this process. At 11 yuan / kg, the revenue is 5600 yuan. This reduces outsourcing volume by 90%, saving 900 yuan in outsourcing costs (1000 yuan / ton). The total revenue is 5600 + 900 = 6500 yuan. The cost of treatment agents and composite additives is 2200 yuan, and labor and other costs are calculated at 500 yuan / ton, bringing the total expenditure to 2200 + 500 = 2700 yuan. The net profit from the recycling of each ton of the mixture of floating oil and waste emulsion from the hot-rolled aluminum emulsion is 6500 - 2700 = 3800 yuan. If the annual processing volume is 300 tons, the net profit is 300 * 3800 = 1140,000 yuan, indicating that the entire investment can be recovered in 1-2 years.

[0052] Example 2

[0053] The flotation agent used in this embodiment is composed of the following components in parts by weight: 28 parts sodium alkylbenzene sulfonate, 20 parts sodium hydroxide, 7 parts sodium carbonate, 15 parts sodium propionate, and 30 parts light white oil.

[0054] The composite additive is composed of the following components in parts by weight: 40 parts oleic acid, 18 parts triethanolamine, 5 parts triethanolamine borate, 10 parts Tween, 10 parts Span, and 12 parts fatty alcohol polyoxyethylene ether, 3 parts oily antioxidant, and 2 parts stabilizer. The oily antioxidant is T501, and the stabilizer is a mixture of isohexanediol and ethanol in a mass ratio of 3:2.

[0055] A process for recycling and reusing floating oil and waste emulsion in hot-rolled aluminum materials includes the following steps:

[0056] S1. Collect the mixture of floating oil and waste emulsion in hot-rolled aluminum material emulsion, and perform secondary filtration on the mixture to obtain waste residue and oil-water mixture; the waste residue is processed by pressure filtration and then outsourced; the oil-water mixture is allowed to stand for 12 hours, and then the oil and water are separated to obtain oil phase 1 and water phase 1, with a volume ratio of oil phase 1 to water phase 1 of 2:1.

[0057] S2. Add flotation agent to aqueous phase 1, wherein the mass of flotation agent is 2.5% of the mass of aqueous phase 1, introduce air for 2 min, let stand for 120 min, and black aluminum powder and other solid particles form a suspension, and separate oil phase 2 and aqueous phase 2, wherein the volume ratio of oil phase 2 to aqueous phase 2 is 1:19.

[0058] S3. Mix oil phase 1 and oil phase 2, heat to 70°C, and slowly add 98% sulfuric acid solution while stirring. The amount of sulfuric acid solution added is 8% of the total volume of the mixture of oil phase 1 and oil phase 2. Continue stirring for 90 minutes, then add 10% sodium hydroxide solution to make the water-soluble pH value 7.8. Let stand for 24 hours, and separate the solid and liquid to obtain regenerated lubricating oil and waste residue. The waste residue is outsourced for treatment after pressure filtration.

[0059] S4. Add a composite additive to the recycled lubricating oil, wherein the mass of the composite additive is 25% of the mass of the recycled lubricating oil, and blend it into an emulsified oil.

[0060] S5. Add aqueous phase 2 and tap water (added as needed) to the emulsified oil obtained in S4, wherein the total mass ratio of aqueous phase 2 and tap water (added as needed) to the mass ratio of emulsified oil is 2:1. Add 20 ppm of disodium EDTA and stir thoroughly to prepare a hot-rolled concentrated emulsion. The performance of the hot-rolled concentrated emulsion was tested, and its performance indicators are shown in Table 2, meeting the requirements of the SH / T0365-92 emulsified oil standard.

[0061] Table 2 Performance Indicators of Hot-Rolled Concentrated Emulsion

[0062]

[0063] Each ton of the mixture of floating oil and waste emulsion from the S1 aluminum hot-rolling emulsion can regenerate 680 kg of hot-rolling emulsion oil through this process. At 11 yuan / kg, the revenue is 7480 yuan. This reduces outsourcing volume by 85%, saving 850 yuan (1000 yuan / ton) in outsourcing costs. The total revenue is 7480 + 850 = 8330 yuan. The cost of processing agents and composite additives is 3750 yuan, and labor and other costs are calculated at 500 yuan / ton, bringing the total expenditure to 3750 + 500 = 4250 yuan. The net profit from the recycling of each ton of S1 mixture is 8330 - 4250 = 4080 yuan. If the annual processing volume is 300 tons, the net profit is 300 * 4080 = 1224,000 yuan. Therefore, the entire investment can be recovered in 1-2 years.

[0064] Example 3

[0065] The flotation agent used in this embodiment is composed of the following parts by weight: 45 parts sodium alkylbenzene sulfonate, 20 parts sodium hydroxide, 15 parts sodium carbonate, 10 parts sodium propionate, and 10 parts light white oil.

[0066] The compound additive is composed of the following components in parts by weight: 36 parts oleic acid, 16 parts triethanolamine, 10 parts triethanolamine borate, 6 parts Tween, 6 parts Span, and 18 parts fatty alcohol polyoxyethylene ether, 5 parts oily antioxidant, and 3 parts stabilizer. The oily antioxidant is composed of T501 and T551 in a mass ratio of 4:1, and the stabilizer is composed of glycerol and propylene glycol derivative in a mass ratio of 1:1.

[0067] A process for recycling and reusing floating oil and waste emulsion in hot-rolled aluminum materials includes the following steps:

[0068] S1. Collect the mixture of floating oil and waste emulsion in hot-rolled aluminum material emulsion, and perform secondary filtration on the mixture to obtain waste residue and oil-water mixture; the waste residue is processed by pressure filtration and then outsourced; the oil-water mixture is allowed to stand for 12 hours, and then the oil and water are separated to obtain oil phase 1 and water phase 1, with a volume ratio of 4:1.

[0069] S2. Add flotation agent to aqueous phase 1, wherein the mass of flotation agent is 3.5% of the mass of aqueous phase 1, introduce air for 2 min, let stand for 120 min, and solid particles such as black aluminum powder form a suspension, and separate oil phase 2 and aqueous phase 2, wherein the volume ratio of oil phase 2 to aqueous phase 2 is 1:17.

[0070] S3. Mix oil phase 1 and oil phase 2, heat to 50°C, and slowly add 98% sulfuric acid solution while stirring. The amount of sulfuric acid solution added is 10% of the total volume of the mixture of oil phase 1 and oil phase 2. Continue stirring for 90 minutes, then add 10% sodium hydroxide solution to make the water-soluble pH value 7.2. Let stand for 24 hours, and separate the solid and liquid to obtain regenerated lubricating oil and waste residue. The waste residue is outsourced for treatment after pressure filtration.

[0071] S4. Add a composite additive to the recycled lubricating oil, wherein the mass of the composite additive is 20% of the mass of the recycled lubricating oil, and blend it into an emulsified oil;

[0072] S5. Add aqueous phase 2 and tap water (as needed) to the emulsified oil, wherein the total mass ratio of aqueous phase 2 and tap water to the emulsified oil is 1.5:1. Add 20 ppm of disodium EDTA and stir thoroughly to prepare a hot-rolled concentrated emulsion. The performance of the hot-rolled concentrated emulsion is tested, and its performance indicators are shown in Table 3, meeting the requirements of the SH / T0365-92 emulsified oil standard.

[0073] Table 3 Performance Indicators of Hot-Rolled Concentrated Emulsion

[0074]

[0075]

[0076] The mixture of floating oil and waste emulsion from each ton of S1 aluminum hot-rolling emulsion can regenerate 800 kg of hot-rolling emulsion oil through this process. At 11 yuan / kg, the revenue is 8800 yuan. This reduces outsourcing volume by 90%, saving 900 yuan (1000 yuan / ton) in outsourcing costs. The total revenue is 8800 + 900 = 9780 yuan. The cost of treatment agents and composite additives is 4150 yuan, and labor and other costs are calculated at 500 yuan / ton, bringing the total expenditure to 4150 + 500 = 4650 yuan. The net profit from the recycling of each ton of S1 mixture is 9780 - 4650 = 5130 yuan. If the annual processing volume is 300 tons, the net profit is 300 * 5130 = 1539,000 yuan. Therefore, the entire investment can be recovered in 1-2 years.

Claims

1. A process for recycling and reusing floating oil and waste emulsion in hot-rolled aluminum materials, comprising the following steps: S1. Collect the mixture of floating oil and waste emulsion in the hot-rolled aluminum emulsion, and perform secondary filtration on the mixture to obtain waste residue and oil-water mixture; let the oil-water mixture stand, and then separate the oil and water to obtain oil phase 1 and water phase 1; the waste residue is processed by pressure filtration and then outsourced. S2. Add flotation agent to aqueous phase 1 obtained in step S1, introduce air for a preset time, let stand, and separate oil phase 2 and aqueous phase 2. S3. Mix the oil phase 1 obtained in step S1 and the oil phase 2 obtained in step S2, heat to the set temperature, add strong acid while stirring, then continue stirring, then add alkali to adjust the water-soluble pH value to the set range, let stand, and perform solid-liquid separation to obtain regenerated lubricating oil and waste residue. The waste residue is processed by pressure filtration and then outsourced. S4. Add composite additives to the regenerated lubricating oil obtained in step S3 and formulate it into an emulsified oil. S5. Add the aqueous phase 2 obtained in step S2 and the water to be added as needed to the emulsified oil obtained in step S4 according to the preset ratio to prepare a hot-rolled concentrated emulsion, so as to realize the recycling and reuse of floating oil and waste emulsion in the hot-rolled emulsion of aluminum. In step S2, the flotation agent is composed of the following components in parts by weight: 10-50 parts sodium alkylbenzene sulfonate, 20-50 parts sodium hydroxide, 5-15 parts sodium carbonate, 5-15 parts sodium propionate, and 5-30 parts light white oil. In step S4, the composite additive is composed of the following components in parts by weight: 1-5 parts of oily antioxidant, 20-50 parts of oleic acid, 10-30 parts of triethanolamine, 3-15 parts of triethanolamine borate, 5-30 parts of Span, 5-30 parts of Tween, 10-30 parts of fatty alcohol polyoxyethylene ether, and 1-5 parts of stabilizer.

2. The recycling process according to claim 1, characterized in that, The oily antioxidant is at least one of T501, T502, and T551; the stabilizer is at least one of ethanol, glycerol, isohexyl glycol, and propylene glycol derivatives.

3. The recycling process according to claim 1, characterized in that, In step S1, the oil-water mixture is left to stand for 4 to 24 hours.

4. The recycling process according to claim 1, characterized in that, In step S2, the amount of flotation agent added is 2.5% to 5% of the mass of aqueous phase 1; the time for introducing air is 2 to 3 minutes; and the settling time is 30 to 120 minutes.

5. The recycling process according to claim 1, characterized in that, In step S3, the set temperature is 50-100℃; the stirring time is 30-120 min; the strong acid is at least one of sulfuric acid, hydrochloric acid, and perchloric acid; when the strong acid is sulfuric acid, its mass concentration is 90%-98%, and the amount added is 5%-10% of the total volume of oil phase 1 and oil phase 2; the alkali is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate; the water-soluble pH value is set in the range of 6-10; and the standing time is 4h-24h.

6. The recycling process according to claim 1, characterized in that, In step S4, the amount of the composite additive added is 15% to 25% of the mass of the regenerated lubricating oil.

7. The recycling process according to claim 1, characterized in that, In step S5, the ratio of the total mass of the aqueous phase 2 and the water added as needed to the mass of the emulsified oil is (1~2):

1.

8. The recycling process according to claim 1, characterized in that, In step S5, when preparing the hot-rolled emulsion, pH adjuster, bactericide and disodium ethylenediaminetetraacetate are added as needed according to the working conditions and water quality.

Images