A method for regenerating waste mineral oil

Abstract

The present application relates to the technical field of waste mineral oil treatment, and specifically discloses a waste mineral oil regeneration treatment method. The waste mineral oil regeneration treatment method of the present application comprises the following steps: adding an alkaline regulator to the waste mineral oil, filtering, and obtaining pretreated waste mineral oil; preheating the pretreated waste mineral oil, distilling at atmospheric pressure, and preheating the pretreated waste mineral oil, distilling at atmospheric pressure to obtain a light component one and a heavy component one; the heavy component one is repeatedly heated and vacuum distilled, and the components after distillation are heat exchanged and condensed to obtain crude oil one and crude oil two; the light component one is condensed and then separated from oil and water to obtain light fuel oil; the crude oil one and the crude oil two are respectively mixed with an extraction solvent, and refined oil is extracted from the top of the extraction tower, and the bottom of the tower is extracted oil, and the extracted oil is heated by a flash tower, and the top of the tower is condensed to be a fresh solvent, and the bottom of the tower is extracted oil. The waste mineral oil regeneration treatment method of the present application has a high base oil recovery rate and better performance.

Description

Technical Field

[0001] The present application relates to the technical field of waste mineral oil treatment, and more specifically, to a waste mineral oil regeneration treatment method. Background Art

[0002] Waste mineral oil is a type of oil that loses its original properties during use due to contamination by foreign impurities, water absorption, high-temperature thermal decomposition, and oxidation. There are many types of waste mineral oil, which can be divided into waste engine oil, industrial lubricants, hydraulic oil, kerosene, and sludge according to their use. Waste mineral oil often contains a variety of toxic substances, such as polychlorinated biphenyls (PCBs), heavy metals added to improve oil performance, and additives such as chlorine, sulfur, and phosphorus, which are recognized carcinogenic and mutagenic compounds. The indiscriminate dumping of waste mineral oil is severely toxic to the ecological environment and living organisms; if waste mineral oil is poured into the soil, it can cause plant death; if it enters a drinking water source, 1 ton of waste oil can contaminate 1 million tons of drinking water.

[0003] The market capacity and potential of China's waste mineral oil market are rapidly increasing with the development of my country's economy. With the increasing depletion of oil resources and the continuous rise in oil prices, the recycling of waste mineral oil has also received great attention from countries around the world.

[0004] At present, the method for treating waste mineral oil includes the following steps: step 1, adding an organic solvent to a glass reactor, starting stirring, adding raw materials while stirring, and then turning on the heating. After the raw materials and the organic solvent are fully mixed, the heating is turned off, and a reaction hot liquid is generated at this time; step 2, filtering the reaction hot liquid generated in step 1 into a barrel, and then naturally cooling the barrel until solid precipitates, and then placing the barrel in an environment below 30°C for crystallization for 6 hours to obtain a solid; the waste mineral oil can be converted from liquid to solid powder. At this time, the solid powdered mineral oil is generally treated by burying, thereby reducing the impact of waste mineral oil emissions on the environment.

[0005] Converting waste mineral oil from liquid to solid powder and then landfilling it reduces the impact on the environment, but there is still usable base oil in the waste mineral oil, which leads to waste of base oil. Summary of the Invention

[0006] In order to improve the recovery rate of base oil in waste mineral oil and reduce the impact of waste mineral oil on the environment, the present application provides a waste mineral oil regeneration method.

[0007] This application provides a waste mineral oil regeneration method, which adopts the following technical solution:

[0008] A method for regenerating waste mineral oil comprises the following steps:

[0009] (1) Pretreatment: adding an alkaline regulator to the waste mineral oil and filtering to obtain pretreated waste mineral oil;

[0010] (2) distillation: preheating and distilling the pretreated waste mineral oil obtained in step (1) under normal pressure, and preheating and distilling the pretreated waste mineral oil under normal pressure to obtain a light component 1 and a heavy component 1; the heavy component 1 is further subjected to heating and vacuum distillation, and the components after distillation are heat exchanged and condensed to obtain crude oil 1 and crude oil 2; the light component 1 is condensed and then subjected to oil-water separation to obtain light fuel oil;

[0011] (3) Solvent refining: Crude oil 1 and crude oil 2 are mixed with extraction solvent respectively. Refined oil is extracted from the top of the extraction tower, and the bottom of the tower is extracted oil. The extracted oil is heated in a flash tower, and the top of the tower is condensed to produce fresh solvent, and the bottom of the tower is extracted oil.

[0012] Preferably, the crude oil 1 is 150# crude oil; the crude oil 2 is 350# crude oil;

[0013] Preferably, the extraction in step (3) is carried out in an extraction tower, and the extraction solvent is N-methylpyrrolidone; the extraction tower is temperature-controlled in layers, wherein the temperature of the upper layer is 100-130°C and the temperature of the lower layer is 50-60°C, the upper part of the tower extracts refined oil, and the bottom of the tower contains extracted oil and extraction solvent. The mass ratio of extraction solvent to oil is 1:1.

[0014] Preferably, the mass ratio of the alkaline regulator to the waste mineral oil is (1-5):100.

[0015] Preferably, the extracted oil in step (3) enters a solvent stripping tower for stripping, 150° C. steam is introduced into the stripping tower, and the water vapor removes the extraction solvent in the extracted oil. The extraction solvent enters a solvent drying tower after condensation, and the solvent is dried and recovered. The extracted oil at the bottom of the tower flows into the residual oil tank in the storage tank area.

[0016] By adopting the above technical solution, the waste mineral oil regeneration treatment method provided by the present application has a simple process. By combining pretreatment, distillation, and solvent extraction, the pickling process is reduced, and the generation of secondary pollution is reduced. The recovered base oil has high quality, low acidity, and low content of other impurities, and the base oil recovery rate is high.

[0017] The waste mineral oil of the present application undergoes a pretreatment step before distillation. An alkaline regulator is added to the waste mineral oil to neutralize the waste mineral oil and remove some of the acidic substances in the waste mineral oil. At the same time, ash and metal slag are filtered out. The waste mineral oil is heated to a certain temperature by atmospheric distillation to vaporize the organic components in the waste mineral oil into steam, which is then cooled by a condensing device to produce base oil. Subsequently, vacuum distillation is further used to separate the components in the waste mineral oil, so that water and light components such as light oil in the waste mineral oil are separated by vacuum evaporation. Other raw oils are further separated.

[0018] The use of solvent refining can improve the recovery efficiency of base oil in waste mineral oil and has good environmental protection effects.

[0019] Preferably, in step (1), the alkaline regulator is mainly made of the following raw materials in parts by weight: 10-20 parts of a neutralizer, 5-10 parts of a flocculant, and 2-5 parts of an auxiliary agent, wherein the auxiliary agent is at least two of tetrapod-shaped zinc oxide whiskers, water-swellable rubber, polyacrylamide, and attapulgite.

[0020] Preferably, the neutralizing agent is sodium hydroxide.

[0021] By adopting the above technical solution, in step (1), a pretreatment agent is used to replace the alkaline regulator, and the pretreatment agent includes a neutralizer, a flocculant, and an auxiliary agent. The three raw materials of the neutralizer, flocculant, and auxiliary agent cooperate with each other to reduce impurities in the waste mineral oil after pretreatment, wherein the neutralizer is used to neutralize the acidic substances in the waste mineral oil to form a residue, and the flocculant and the auxiliary agent work together to make the small particle impurities in the waste mineral oil agglomerate and become larger, and then be filtered out from the waste mineral oil; the four-needle zinc oxide whisker in the auxiliary agent is a three-dimensional four-needle structure, the whisker has a core, and four needle-shaped crystals extend radially from the core, each needle-shaped body is a single crystal microfiber, and the four-needle zinc oxide whisker is a hydrophilic material and oleophobic, and is not easy to adhere to the surface of the waste mineral oil, and the needle tip of the whisker scratches the waste mineral oil. The oil protective film on the surface of large solid particles in the oil continues to sink and grow larger under the action of the flocculant, and is thus filtered out, making it easier to clean up solid impurities in the waste mineral oil and, at the same time, reducing the oil carried on the surface of the solid impurities; the water-absorbing and swelling rubber in the auxiliary agent is easy to absorb water, thereby increasing the size of the rubber particles and facilitating the precipitation of the rubber particles; the silicon-oxygen structure on the surface of the attapulgite is a polar hydroxyl group, and there are a large number of exchangeable hydrophilic inorganic cations, which has extremely strong hydrophilicity and is easy to adsorb water and other small molecule olefins in the waste mineral oil; and the attapulgite is fibrous, which is easy to intertwine with the four-needle zinc oxide whiskers, thereby improving the cleaning of impurities in the waste mineral oil; polyacrylamide is easy to have an adsorption effect on negatively charged particles, and is easy to cooperate with the flocculant to clean up the negatively charged impurities in the waste mineral oil.

[0022] Preferably, the auxiliary agent is composed of tetrapod-shaped zinc oxide whiskers, water-swellable rubber, polyacrylamide, and attapulgite in a mass ratio of (2-5):(1-2):(1-2):(1-2).

[0023] Preferably, the attapulgite is modified attapulgite, and the preparation method of the modified attapulgite comprises the following steps: roasting the attapulgite to obtain pretreated attapulgite, activating the pretreated attapulgite in hydrochloric acid, washing, and drying.

[0024] Preferably, the calcination temperature is 400°C.

[0025] Preferably, the molar concentration of the hydrochloric acid is 2 mol / L, the activation time is 24 h, and the product is dried in a drying oven at a drying temperature of 105° C.

[0026] By adopting the above technical solution, the auxiliary agent is obtained by compounding four components: four-needle zinc oxide whiskers, water-swellable rubber, polyacrylamide, and attapulgite. The ratio of the four components is adjusted to achieve the optimal ratio. The four components in the auxiliary agent cooperate with the neutralizer and flocculant to further reduce the water and other impurities in the waste mineral oil after pretreatment. At the same time, the waste mineral oil carried on the surface of other impurities is reduced, thereby improving the recovery rate of the waste mineral oil and, at the same time, improving the quality of the recovered base oil.

[0027] Preferably, the four-needle zinc oxide whiskers are modified four-needle zinc oxide whiskers. The preparation method of the modified four-needle zinc oxide whiskers comprises the following steps: immersing sepiolite in an acrylic emulsion containing a pore-forming agent to obtain pretreated sepiolite, mixing the pretreated sepiolite with the four-needle zinc oxide whiskers, and drying to obtain the modified four-needle zinc oxide whiskers.

[0028] Preferably, the pore-forming agent is ammonium bicarbonate.

[0029] By adopting the above technical solution, the sepiolite is porous and has a large specific surface area, and has excellent adsorption properties, which makes it easy to remove undesirable components such as colloids, acids, esters, nitrogen-containing compounds, etc. present in the waste mineral oil, thereby reducing the acid value of the recovered base oil. The surface of the sepiolite immersed in the acrylic emulsion contains a sticky layer. The addition of a pore-forming agent facilitates increasing the porosity of the bonding layer, thereby increasing the porosity of the sepiolite. The tetrapod-shaped zinc oxide whiskers are bonded to the surface of the sepiolite, which facilitates increasing the weight of the tetrapod-shaped zinc oxide whiskers and facilitating better dispersion of the tetrapod-shaped zinc oxide whiskers in the waste mineral oil, thereby achieving a better effect of removing impurities from the waste mineral oil.

[0030] Preferably, the flocculant is composed of polyaluminum chloride, polyferric sulfate and calcium chloride in a mass ratio of (3-5):(1-2):(1-2).

[0031] By adopting the above technical solution, a flocculant is obtained by compounding three components: polyaluminum chloride, polyferric sulfate, and calcium chloride. The ratio of the three components is adjusted to achieve an optimal ratio. The calcium ions in the calcium chloride collide with the oil-water interface film of the waste mineral oil, destroying the stability of the waste mineral oil; at the same time, the calcium ions adsorb negatively charged tiny oil particles in the waste mineral oil and compress the double layer of the negatively charged tiny oil particles, thereby reducing the repulsive force between the tiny oil particles and causing them to aggregate into larger oil droplets; the polyaluminum chloride and polyferric sulfate cooperate with each other to compress the double layer of the waste mineral oil particles or neutralize the surface charge, thereby transforming the particles from a repulsive state to a cohesive state capable of contact and collision, destroying the protective film around the oil particles, and achieving an oil-water separation state.

[0032] Preferably, the non-condensable gas and respiratory gas generated during the distillation process are absorbed by alkali and incinerated to heat the low-temperature material.

[0033] By adopting the above technical solution, the non-condensable gases are small molecular hydrocarbons, hydrogen sulfide, sulfur dioxide, etc., and alkali is used to absorb the non-condensable gases, and the non-condensable gases are incinerated, so as to reduce the impact of the non-condensable gases on the environment, and at the same time make full use of the non-condensable gases and improve resource utilization.

[0034] Preferably, the filtration in step (1) adopts a polyetheramide composite membrane.

[0035] By adopting the above technical solution and using a polyetheramide composite membrane for filtration, insoluble impurities and most of the water can be directly removed, which can greatly improve the quality of waste mineral oil recovery and achieve a better concentration effect of the waste mineral oil solution.

[0036] Preferably, the refined oil in step (3) is flash evaporated under negative pressure, and the extracted extraction solvent is recovered.

[0037] Preferably, the refined oil in step (3) is pumped into a flash tower, and the flash tower is under negative pressure and has a temperature of 260° C. The extraction solvent sifted from the top of the tower is recovered after condensation.

[0038] By adopting the above technical solution, the refined oil is flash evaporated under negative pressure, which facilitates further reduction of the extraction solvent in the refined oil. At the same time, the extracted solvent is recovered to realize the recycling and reuse of waste mineral oil while maximizing the comprehensive recovery of resources, reducing the input of extraction solvent, reducing costs, saving resources, and reducing energy consumption.

[0039] Preferably, the refined oil in step (3) is subjected to steam stripping treatment, and the extraction solvent after steam stripping is recovered.

[0040] Preferably, the refined oil in step (3) is subjected to a stripping treatment. The stripping is carried out in a stripping tower, into which steam is introduced at a temperature of 150° C. The steam condenses the extraction solvent and is then dried and recovered.

[0041] By adopting the above technical solution, the stripping method for treating refined oil facilitates the reduction of solvents and other impurities in the refined oil, reducing residual moisture and acid content in the refined oil, thereby lowering the acid value of the recovered base oil and improving the quality of the refined oil. At the same time, the extraction solvent after stripping is recovered, which further reduces the input of extraction solvent, lowers costs, and conserves resources.

[0042] Preferably, the extraction solvent is composed of N-methylpyrrolidone, furfural, n-butanol, and epichlorohydrin in a mass ratio of (3-4):(2-4):(1-2):(1-2).

[0043] By adopting the above technical solution, furfural and N-methylpyrrolidone have different solubilities in ideal components and non-ideal components in waste mineral oil, and the polarities of furfural and N-methylpyrrolidone are relatively close to the polarities of non-ideal components, such as aromatic hydrocarbons and olefins. Therefore, during the heating process, non-ideal components are easily dissolved in furfural and N-methylpyrrolidone, and the addition of epichlorohydrin facilitates improving the thermal stability of furfural and N-methylpyrrolidone; the addition of n-butanol facilitates appropriately reducing the polarity of furfural and N-methylpyrrolidone, so as to better increase the solubility of non-ideal components, and n-butanol also has solubility for non-ideal components. The four components of N-methylpyrrolidone, furfural, n-butanol, and epichlorohydrin cooperate with each other, thereby improving the quality of the recovered base oil.

[0044] In summary, this application has the following beneficial effects:

[0045] 1. The waste mineral oil regeneration method of the present application adopts the methods of pretreatment, distillation and solvent refining, which reduces the pickling process and improves the quality of the recovered base oil. The acid value and sulfur content of the recovered base oil are both low.

[0046] 2. In the waste mineral oil regeneration method of the present application, during the pretreatment process of step (1), the alkaline regulator is mixed with the waste mineral oil and then filtered, thereby facilitating the reduction of acidic impurities and large particle residues in the waste mineral oil, thereby improving the quality of the recovered base oil.

[0047] 3. In the pretreatment process of step (1) of the waste mineral oil regeneration method of the present application, the alkaline regulator includes three raw materials: an auxiliary agent, a neutralizing agent, and a flocculant. The three raw materials cooperate with each other to improve the quality of the recovered base oil. DETAILED DESCRIPTION

[0048] The present application is further described in detail below with reference to the embodiments.

[0049] The processes, conditions, experimental methods, etc. used in implementing the present invention, except for those specifically mentioned below, are all common knowledge and common general knowledge in the art. The protection content of the present invention is not limited to the following embodiments. Variations and advantages that can be imagined by those skilled in the art without departing from the spirit and scope of the inventive concept are all included in the present invention.

[0050] Example

[0051] Example 1: A method for regenerating waste mineral oil, comprising the following steps:

[0052] (1) Pretreatment: adding an alkaline regulator to waste mineral oil to obtain a mixture, and pumping the mixture to a sealed raw material tank. A membrane material is provided at the inlet of the raw material tank to intercept and filter impurities such as residues in the oil to obtain pretreated waste mineral oil; wherein the alkaline regulator is sodium hydroxide with a mass fraction of 40%; the membrane material is a polyetheramide composite membrane; and the mass ratio of the alkaline regulator to the waste mineral oil is 2:100;

[0053] (2) Distillation:

[0054] S1 preheating: the pretreated waste mineral oil obtained in step (1) is fed into a distillation tower for distillation, the pretreated waste mineral oil is transported to a heat exchanger by an oil pump, and crude oil is obtained by vacuum fractionation. The crude oil is preheated to 80° C. in the heat exchanger and then heated in a normal pressure tubular heating furnace;

[0055] S2 normal pressure heating: the crude oil from step S1 is heated to 330°C in a normal pressure tubular heating furnace and then enters the normal pressure distillation tower;

[0056] S2 atmospheric distillation: The crude oil is separated into light components and heavy components in the atmospheric distillation tower. The light components are vaporized, condensed in the condenser, and then enter the diesel storage tank. The heavy components enter the vacuum tube furnace for further heating and atmospheric distillation. The light components are extracted by the vacuum unit, condensed, and then enter the oil-water separator for separation. The separated light fuel oil enters the oil tank for temporary storage and then sale. The oily wastewater enters the oily wastewater storage tank.

[0057] S3 vacuum heating: The heavy component 1 is heated to 390°C in a vacuum tube furnace and then enters the vacuum distillation tower;

[0058] S4 vacuum distillation: The vacuum distillation tower is evacuated to a vacuum degree of less than 1 kPa by a Roots vacuum pump. The heated heavy component 1 is separated in the vacuum distillation tower due to the different fractional gravities. The top portion is the light component 2, which is condensed to obtain crude oil 1 and temporarily stored in a crude oil 1 storage tank. The middle portion is the medium component, which is condensed to obtain crude oil 2 and temporarily stored in a crude oil 2 storage tank. The bottom portion is the heavy component 2, which is stored in an asphalt modifier storage tank. The non-condensable gas and respiratory gas generated during the distillation process are absorbed by alkali and incinerated in a tubular furnace.

[0059] (3) Solvent refining: The crude oil 1 and crude oil 2 obtained in step (2) are mixed with an extraction solvent respectively, and refined oil is extracted from the upper part of the tower, and the extracted oil and extraction solvent are at the bottom of the tower. The extraction and refining in the extraction tower has a ratio of extraction solvent to crude oil of 1:1, and the extraction solvent is N-methylpyrrolidone. The extraction tower is temperature-controlled by layers, wherein the temperature of the upper layer is controlled at 100°C-130°C, and the temperature of the lower layer is controlled at 50°C-60°C. Refined oil is extracted from the upper part of the tower, and the extracted oil and extraction solvent are at the bottom of the tower; the extracted oil and extraction solvent at the bottom of the extraction tower enter a solvent recovery tower to recover the solvent, and the pressure in the tower is -0.08MPa and the temperature is 220°C-260°C. The extraction solvent vapor at the top of the tower flows into the solvent recovery tank after condensation, and the oil extracted from the bottom of the tower enters the solvent stripping tower for stripping. 150°C steam is introduced into the stripping tower, and the water vapor carries out the extraction solvent in the extracted oil. After condensation, it enters the solvent drying tower for drying and recovery of the solvent; the oil extracted from the bottom of the tower flows into the residual oil tank in the storage tank area.

[0060] Working principle of solvent drying tower: solvent is recovered by negative pressure vacuum drying and steam stripping.

[0061] Example 2: A method for regenerating waste mineral oil, which differs from Example 1 in that: in step (1), the alkaline regulator includes the following raw materials by weight: 10 kg of a neutralizer, 5 kg of a flocculant, and 2 kg of an auxiliary agent, wherein the neutralizer is sodium hydroxide, the flocculant is composed of polyaluminum chloride, polyferric sulfate, and calcium chloride in a mass ratio of 3:1:1; and the auxiliary agent is composed of tetrapod-shaped zinc oxide whiskers and water-swellable rubber in a mass ratio of 1:1.

[0062] Example 3: A method for regenerating and treating waste mineral oil, which differs from Example 1 in that: in step (1), the alkaline regulator includes the following raw materials by weight: 20 kg of a neutralizer, 10 kg of a flocculant, and 5 kg of an auxiliary agent, wherein the neutralizer is sodium hydroxide, the flocculant is composed of polyaluminum chloride, polyferric sulfate, and calcium chloride in a mass ratio of 5:2:2, and the auxiliary agent is composed of polyacrylamide and attapulgite in a mass ratio of 1:1. The attapulgite is modified attapulgite, and the preparation method of the modified attapulgite includes the following steps: calcining the attapulgite to obtain pretreated attapulgite, activating the pretreated attapulgite in hydrochloric acid, washing, and drying. The calcination temperature is 400°C, the molar concentration of the hydrochloric acid is 2 mol / L, the activation time is 24 hours, and the drying is performed in a drying oven at a drying temperature of 105°C.

[0063] Example 4: A method for regenerating waste mineral oil, which differs from Example 3 in that the auxiliary agent is composed of tetrapod-shaped zinc oxide whiskers, water-swelling rubber, polyacrylamide, and attapulgite in a mass ratio of 2:1:1:1.

[0064] Example 5: A method for regenerating waste mineral oil, which differs from Example 3 in that the auxiliary agent is composed of tetrapod-shaped zinc oxide whiskers, water-swelling rubber, polyacrylamide, and attapulgite in a mass ratio of 5:2:2:2.

[0065] Example 6: A method for regenerating waste mineral oil, differing from Example 5 in that the tetrapod-shaped zinc oxide whiskers are modified tetrapod-shaped zinc oxide whiskers. The preparation method of the modified tetrapod-shaped zinc oxide whiskers comprises the following steps: immersing sepiolite in an acrylic emulsion containing a pore-forming agent for 15 minutes to obtain pretreated sepiolite; mixing the pretreated sepiolite with the tetrapod-shaped zinc oxide whiskers in a mass ratio of 1:5; and drying the mixture. The pore-forming agent is ammonium bicarbonate. The mass ratio of the pore-forming agent to the acrylic emulsion is 3:50.

[0066] Example 7: A method for regenerating waste mineral oil, which differs from Example 1 in that: the refined oil obtained in step (3) is flash evaporated under negative pressure; the flash evaporation step is: pumped into a flash evaporation tower, the flash evaporation tower is at negative pressure, the pressure is -0.08MPa, the temperature is controlled at 260°C, the extraction solvent evaporated from the top of the tower is condensed in a condenser and then refluxed into the solvent recovery tank.

[0067] Example 8: A method for regenerating waste mineral oil, differing from Example 1 in that the refined oil obtained in step (3) is subjected to steam stripping. The refined oil enters a base oil stripping tower for stripping to further remove the solvent. 150°C steam is introduced into the stripping tower, and the steam removes the extraction solvent from the refined oil. After condensation, the solvent enters a solvent drying tower for drying and recovery.

[0068] Example 9: A method for regenerating and treating waste mineral oil, which differs from Example 1 in that the refined oil obtained in step (3) is first flash evaporated under negative pressure and then subjected to stripping treatment. That is, the extracted refined oil contains a small amount of extraction solvent, which is pumped into a flash tower. The flash tower is under negative pressure, with a pressure of -0.08 MPa and a temperature controlled at 260°C. The extraction solvent evaporated from the top of the tower is condensed in a condenser and then refluxed into a solvent recovery tank. The refined oil at the bottom of the tower enters a base oil stripping tower for stripping to further remove the solvent. 150°C steam is introduced into the stripping tower, and the water vapor carries out the extraction solvent in the refined oil, which is then condensed and enters a solvent drying tower for drying and recovery.

[0069] Example 10: A method for regenerating waste mineral oil, which differs from Example 9 in that the extraction solvent consists of N-methylpyrrolidone, furfural, n-butanol, and epichlorohydrin in a mass ratio of 1:1:1:1.

[0070] Example 11: A method for regenerating waste mineral oil, which differs from Example 9 in that the extraction solvent consists of N-methylpyrrolidone, furfural, n-butanol, and epichlorohydrin in a mass ratio of 3:2:1:1.

[0071] Example 12: A method for regenerating waste mineral oil, which differs from Example 9 in that the extraction solvent is composed of N-methylpyrrolidone, furfural, n-butanol, and epichlorohydrin in a mass ratio of 4:4:2:2.

[0072] Comparative Example

[0073] Comparative Example 1: A method for regenerating waste mineral oil, which differs from Example 2 in that no auxiliary agent is added to the pretreatment agent.

[0074] Comparative Example 2: A method for regenerating waste mineral oil, which differs from Example 2 in that no flocculant is added to the pretreatment agent.

[0075] Comparative Example 3: A method for regenerating waste mineral oil, which differs from Example 2 in that the auxiliary agent in the pretreatment agent is tetrapod-shaped zinc oxide whiskers.

[0076] Comparative Example Comparative Example: A method for regenerating waste mineral oil, which differs from Example 1 in that no alkaline regulator is added in step (1).

[0077] Detection method

[0078] Recovery Test: 500 ml of waste mineral oil was taken and treated according to the treatment methods of Examples 1-6, Comparative Examples 1-3, and the comparative example to obtain recovered base oil, and then the recovery rate of the waste mineral oil was calculated. The recovery rate results are shown in Table 1. The recovery rate calculation formula is as follows:

[0079] Recovery rate = (recovered oil volume / waste mineral oil volume) × 100%

[0080] Acid Value Test of Recovered Base Oil: The acid values ​​of the recovered base oils obtained by the treatment methods of Examples 1-12, Comparative Examples 1-3, and the Comparative Example were tested according to the test method in GB / T4945-2002 "Determination of Acid and Base Number of Petroleum Products and Lubricants (Color Indicator Method)". The acid value test results are shown in Table 1.

[0081] Sulfur Content Testing of Recovered Base Oils: The recovered base oils treated according to the methods of Examples 1-12, Comparative Examples 1-3, and the comparative examples were tested for sulfur content according to the method specified in SH / T0689-2000, "Determination of Total Sulfur Content of Light Hydrocarbons, Motor Fuels, and Other Oils (Ultraviolet Fluorescence Method)." The results are shown in Table 1.

[0082] Table 1 Performance test results of recovered base oil and waste mineral oil of Examples 1-12, Comparative Examples 1-3 and Comparative Examples

[0083]

[0084]

[0085] Combining Example 1, untreated waste mineral oil, and the data in Table 1, it can be seen that the acid value and sulfur content of the recovered base oil obtained by the regeneration treatment method of the present application in Example 1 are both low, and the performance and quality of the recovered base oil obtained by treating the waste mineral oil are better.

[0086] Combining Example 1 and Comparative Example 1, and combining the data in Table 1, it can be seen that the waste mineral oil regeneration method of Example 1 has a high base oil recovery rate, and the recovered base oleic acid esters and sulfur content are both low. The difference between Example 1 and Comparative Example 1 is that Example 1 initially uses an alkaline regulator to treat the waste mineral oil. The inventors of the present application believe that treating the initial waste mineral oil helps to improve the base oil recovery rate and, at the same time, reduces the acid value and sulfur content of the recovered base oil, resulting in better performance of the recovered base oil.

[0087] In combination with Examples 1-3 and the data in Table 1, it can be seen that Examples 2-3 use a homemade alkaline regulator obtained by compounding multiple components. As a result, the base oil recovery rate after treatment is high, and at the same time, the acid value and sulfur content are low, and the performance of the recovered base oil is better.

[0088] Combining Example 2, Comparative Examples 1-3, and the data in Table 1, it can be seen that the base oil recovery rate after treatment in Example 2 is higher than the base oil recovery rates after treatment in Comparative Examples 1-3. At the same time, the acid value and sulfur content of the base oil after treatment in Example 2 are both lower. The pretreatment agent in Example 2 contains three components: a neutralizer, a flocculant, and an adjuvant. The three components cooperate with each other to help improve the effect of waste mineral oil pretreatment, thereby improving the base oil recovery rate. At the same time, the recovered base oil has better performance.

[0089] In combination with Examples 3-5 and the data in Table 1, it can be seen that the waste mineral oil treated in the manner of Examples 4-5 has a relatively high recovery rate, and the performance of the recovered base oil is better. In Examples 4-5, the auxiliary agent is obtained by compounding four components: four-needle zinc oxide whiskers, water-swellable rubber, polyacrylamide, and attapulgite. The ratio of the four components is adjusted, and the four components cooperate with each other to facilitate improving the recovery rate of the waste mineral oil, while reducing the acid value and sulfur content of the recovered base oil.

[0090] In combination with Examples 5-6 and the data in Table 1, it can be seen that the waste mineral oil treated by the method of Example 6 has a higher base oil recovery rate and better performance of the recovered base oil. The difference between Example 6 and Example 5 is that Example 6 uses modified four-needle zinc oxide whiskers to replace the four-needle zinc oxide whiskers, thereby reducing the acid value and sulfur content of the obtained base oil.

[0091] Combining Example 1, Examples 7-9, and the data in Table 1, it can be seen that Examples 7-9 perform subsequent treatment on the refined oil after solvent extraction to facilitate reducing the acid value and sulfur content of the recovered base oil.

[0092] In combination with Examples 9-12 and the data in Table 1, it can be seen that the acid value and sulfur content of the base oil obtained by treating the waste mineral oil using Examples 10-12 are reduced. The difference between Examples 10-12 and Example 9 is that the extraction solvent in Examples 10-12 is obtained by compounding four components: N-methylpyrrolidone, furfural, n-butanol, and epichlorohydrin, so that the quality of the recovered base oil is better.

[0093] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for regenerating waste mineral oil, characterized in that: The steps include: (1) Pretreatment: adding an alkaline regulator to the waste mineral oil and filtering to obtain pretreated waste mineral oil; (2) distillation: preheating and distilling the pretreated waste mineral oil obtained in step (1) under normal pressure to obtain a light component 1 and a heavy component 1; the heavy component 1 is further subjected to heating and vacuum distillation, and the components after distillation are heat exchanged and condensed to obtain crude oil 1 and crude oil 2; the light component 1 is condensed and then separated from oil and water to obtain light fuel oil; (3) Solvent refining: Crude oil 1 and crude oil 2 are mixed with extraction solvents respectively, and refined oil is extracted from the top of the extraction tower, and the bottom of the tower is the extracted oil. The extracted oil is heated in a flash tower, and the top of the tower is condensed to obtain fresh solvent, and the bottom of the tower is the extracted oil; The alkaline regulator in step (1) is mainly made of the following raw materials in parts by weight: 10-20 parts of a neutralizer, 5-10 parts of a flocculant, and 2-5 parts of an auxiliary agent; The auxiliary agent is composed of tetrapod-shaped zinc oxide whiskers, water-swellable rubber, polyacrylamide, and attapulgite in a mass ratio of (2-5):(1-2):(1-2):(1-2); The extraction solvent in step (3) is composed of N-methylpyrrolidone, furfural, n-butanol and epichlorohydrin in a mass ratio of (3-4):(2-4):(1-2):(1-2).

2. A method for regenerating waste mineral oil according to claim 1, characterized in that: The tetrapod-shaped zinc oxide whisker is a modified tetrapod-shaped zinc oxide whisker. The preparation method of the modified tetrapod-shaped zinc oxide whisker comprises the following steps: immersing sepiolite in an acrylic emulsion containing a pore-forming agent to obtain pretreated sepiolite, mixing the pretreated sepiolite with the tetrapod-shaped zinc oxide whisker, and drying to obtain the modified tetrapod-shaped zinc oxide whisker.

3. A method for regenerating waste mineral oil according to claim 2, characterized in that: The flocculant is composed of polyaluminium chloride, polyferric sulfate and calcium chloride in a mass ratio of (3-5):(1-2):(1-2).

4. A method for regenerating waste mineral oil according to claim 1, characterized in that: The non-condensable gas and respiratory gas produced during the distillation process are absorbed by alkali and incinerated.

5. The method for regenerating waste mineral oil according to claim 1, characterized in that: In the step (1), a polyetheramide composite membrane is used for filtration.

6. A method for regenerating waste mineral oil according to claim 1, characterized in that: The refined oil in step (3) is flash evaporated under negative pressure, and the evaporated extraction solvent is recovered.

7. A method for regenerating waste mineral oil according to claim 1, characterized in that: The refined oil in step (3) is subjected to a stripping treatment, and the extraction solvent after stripping is recovered.

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