A pre-extraction assisted-solvent extraction process for oil sands or sludge containing heavy crude oil

Abstract

The application provides a pre-leaching auxiliary solvent extraction method for oil sand or oil sludge containing heavy crude oil, and belongs to the technical field of product separation and solid waste treatment in the field of petroleum chemical industry. The bitumen is dispersed by using aromatic hydrocarbon first, and then extracted by using naphthenic hydrocarbon, so that good extraction effect can be achieved, a surfactant does not need to be added, the solid phase residual oil rate after treatment is less than 1wt%, and the national relevant standard is met; the pre-leaching agent and the extractant used in the application have low boiling points, are easy to distill and recover, and the recovery rate is greater than 85%. In addition, the method provided by the application has the operation temperature of room temperature (20-30 DEG C), the operation condition is mild, the method is simple, the energy consumption is low, the organic solvent and the crude oil (containing bitumen and other heavy components) can be recovered by distillation, and the resource utilization is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of product separation and solid waste treatment in the field of petrochemical industry, and particularly relates to a pre-extraction auxiliary solvent extraction method for oil sand or oil sludge containing heavy crude oil. BACKGROUND

[0002] With the gradual depletion of light crude oil, the exploitation of unconventional oil resources such as oil sand and heavy oil has increased year by year. Oil sand is a mixture of heavy oil such as bitumen and symbiotic minerals such as sand or clay particles, and oil sand resources are abundant. Developing heavy oil resources enriched in oil sand can be used as a substitute for conventional oil resources and play a crucial role in the world's energy supply. Oil sludge is one of the main pollutants generated during oil production and refining, and as the remaining crude oil becomes increasingly heavy, the amount of oil sludge contaminated by heavy crude oil is increasing. For oil sand and oil sludge, the higher the content of heavy components such as asphaltene in the oil phase composition, the more difficult it is to handle. Oil-containing waste generated during oil production and processing is a harmful waste (HW08) included in the National Hazardous Waste List, and if not properly handled, it can pollute the ecological environment and harm human health. With the increasing requirements of national environmental regulations and standards for the treatment of oil-containing waste, efficient separation of bitumen from oil sand, reduction of bitumen residues in tailings, and harmless treatment and resource utilization of oil sludge are difficult problems faced by the industry.

[0003] Solvent extraction is one of the commonly used methods for extracting oil sand bitumen and treating oil sludge. Using the principle of "like dissolves like", the appropriate organic solvent is selected as the extractant to transfer the oil phase to the extractant. The mixture of extractant and oil is separated by distillation to recover the extractant and crude oil. Solvent extraction has the advantages of saving fresh water, no emulsification, wide applicability and high separation efficiency, but a large amount of energy is consumed in the distillation process to recover the solvent, resulting in high treatment cost.

[0004] CN100340503C proposes a method for treating oil-containing sludge, using wide-boiling oil (100℃-500℃) as an extractant, and adopting multi-stage hot extraction to recover oil from oil-containing sludge. The process flow is long, and needs to be operated at a relatively high temperature. At the same time, the distillation reuse temperature of wide-boiling oil is high, and a large amount of energy needs to be consumed. CN111943464B proposes a method for treating oil-containing solid substances such as oil sludge or oil sand, which fully contacts oil-containing solid substances with low-boiling weakly polar or low-boiling non-polar organic solvent liquid under normal temperature and pressure conditions to extract oil into the liquid phase. The low-boiling weakly polar or low-boiling non-polar organic solvent is a hydrocarbon solvent, an aldehyde solvent, a ketone solvent, an ether solvent, etc. which is a gas at normal temperature and pressure or has a boiling point lower than 25℃. After solid-liquid separation, the liquid mixture is gasified and separated by means of pressure reduction or heating evaporation, and then the gasified solvent is recovered by means of compression and condensation. Although the low-boiling organic solvent can be separated more easily by means of pressure reduction or heating gasification, the whole process has a higher requirement for the air tightness of the equipment, and the extraction effect of low-boiling weakly polar or non-polar solvent on heavy component oil such as asphaltene is limited. SUMMARY

[0005] Therefore, the present application aims to provide a pre-extraction auxiliary solvent extraction method for oil sand or oil sludge containing heavy crude oil. The extraction method provided by the present application has the advantages of low distillation reuse temperature of extractant, high recovery rate and outstanding extraction effect, and achieves the goal of harmless treatment and resource utilization of oil sand, oil sludge and other substances.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] The present application provides a pre-extraction auxiliary solvent extraction method for oil sand or oil sludge containing heavy crude oil, comprising the following steps:

[0008] Mixing the oil-containing solid substance with the pre-extraction agent to perform pre-extraction, and obtaining a solid-liquid mixture; the oil-containing solid substance is oil sand or oil sludge containing heavy crude oil; the pre-extraction agent comprises aromatic hydrocarbon; the boiling point of the aromatic hydrocarbon is <150℃;

[0009] Mixing the solid-liquid mixture with the first extractant to perform first extraction, and performing solid-liquid separation to obtain solid phase and liquid phase; the first extractant comprises naphthenic hydrocarbon; the boiling point of the first extractant is <100℃; the solid-liquid separation comprises standing or centrifugation; the standing time is 5-40 min; the centrifugation speed is 300-1000 rpm, and the centrifugation time is 3-10 min.

[0010] Preferably, the aromatic hydrocarbon comprises one or more of benzene, toluene and xylene.

[0011] Preferably, the mass ratio of the oil-containing solid substance to the pre-extraction agent is 1:(0.5-3).

[0012] Preferably, the cycloalkane comprises cyclohexane and / or cyclopentane.

[0013] Preferably, the mass of the solid-liquid mixture is 1:(0.5-3) times the mass of the first extraction agent based on the mass of the oil-containing solid substance.

[0014] Preferably, the oil phase asphaltene content of the oil-containing solid substance is ≥10wt%.

[0015] Preferably, when the oil phase asphaltene content of the oil-containing solid substance is ≥30wt%, the pre-extraction further comprises mixing the oil-containing solid substance with a pre-extraction agent before the pre-extraction; the pre-extraction agent comprises cycloalkane, and the boiling point of the pre-extraction agent is <100℃.

[0016] Preferably, the mass ratio of the oil-containing solid substance to the pre-extraction agent is 1:(1-5).

[0017] Preferably, when the oil phase asphaltene content of the oil-containing solid substance is ≥10wt% and <30wt%, the second extraction further comprises mixing the solid phase with a second extraction agent after the first extraction; the second extraction agent comprises cycloalkane, and the boiling point of the second extraction agent is <100℃.

[0018] Preferably, the mass ratio of the solid phase to the second extraction agent is 1:(1-3) times based on the mass of the oil-containing solid substance.

[0019] The present application provides a pre-extraction auxiliary solvent extraction method for oil sand or oil sludge containing heavy crude oil, comprising the following steps: mixing an oil-containing solid substance with a pre-extraction agent to perform pre-extraction, and obtaining a solid-liquid mixture; the oil-containing solid substance is oil sand or oil sludge containing heavy crude oil; the pre-extraction agent comprises aromatic hydrocarbon; the boiling point of the aromatic hydrocarbon is <150℃; mixing the solid-liquid mixture with a first extraction agent to perform first extraction, and performing solid-liquid separation to obtain a solid phase and a liquid phase; the first extraction agent comprises cycloalkane; the boiling point of the first extraction agent is <100℃; the solid-liquid separation comprises standing or centrifugation; the standing time is 5-40min; the centrifugation speed is 300-1000rpm, and the centrifugation time is 3-10min.

[0020] The present application first uses aromatic hydrocarbon to disperse asphaltene, and then uses cycloalkane to perform extraction, which can achieve good extraction effect, does not need to add surfactant, and the residual oil rate of the solid phase after treatment is lower than 1wt%, which meets the national relevant standards; the pre-extraction agent and the extraction agent used in the present application have low boiling points and are easy to distill and recover, and the recovery rate is greater than 85%.

[0021] In addition, the method provided by the application has the advantages of room temperature (20-30℃) operation, mild operation condition, simple method, low energy consumption, and recovery of organic solvent and crude oil (containing heavy components such as asphaltene) through distillation, and resource utilization.

[0022] Further, when the oil phase asphaltene content of the oil-containing solid substance is ≥30wt%, the application can reduce the amount of subsequent pre-extraction agent by mixing the oil-containing solid substance and the pre-extraction agent for pre-extraction before pre-extraction.

[0023] In addition, the application also has the following advantages:

[0024] The difference from the previous use of a large amount of aromatic hydrocarbon solvent for direct extraction is that asphaltene is a component in crude oil that is insoluble in low normal alkane (such as n-heptane), but can be dissolved in toluene, xylene and other aromatic solvents. For oil sludge or oil sand with high asphaltene content, the amount of toluene and other aromatic hydrocarbon solvents often needs to be increased during solvent extraction to achieve good extraction effect. However, the toxicity of toluene and other aromatic hydrocarbon solvents limits their extensive use. The application found that using a small amount of aromatic hydrocarbon to disperse asphaltene first, and then using naphthene for extraction can achieve the same good extraction effect, reducing the amount of aromatic hydrocarbon used.

[0025] The difference from the mixed solvent extraction is that the mixed solvent (such as a mixed solvent of toluene and cyclohexane) is used for direct extraction, and the asphaltene in the mixed solvent tends to aggregate and precipitate. Adding a mixed solvent cannot disperse the asphaltene in the oil sludge / oil sand, while the application disperses the oil phase (especially the insoluble asphaltene) in the oil sludge or oil sand into the solvent by adding a small amount of aromatic hydrocarbon solvent during pre-extraction, and then uses naphthene for extraction and separation. After adding naphthene, the asphaltene does not aggregate and precipitate in a short period of time, so that the asphaltene and other heavy oil can be effectively separated by short-term standing or low-speed centrifugation. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0027] Figure 1 It is a schematic diagram of the pre-extraction auxiliary solvent extraction process;

[0028] Figure 2 It is a schematic diagram of the Dean-Stark extraction device;

[0029] Figure 3 Photo of oil sand before and after pre-leaching assisted solvent extraction for Example 5 (mass ratio of toluene to cyclohexane = 2:1);

[0030] Figure 4 Photo of oil sand before and after pre-leaching assisted solvent extraction for Example 9 (mass ratio of toluene to cyclohexane = 2:1);

[0031] Figure 5 Photo of oil sand before and after pre-leaching assisted solvent extraction for Example 12 (mass ratio of xylene to cyclopentane = 2:1);

[0032] Figure 6 Photo of oil sand before and after pre-leaching assisted solvent extraction for Example 15 (mass ratio of benzene to cyclopentane = 2:1). DETAILED DESCRIPTION

[0033] The present application provides a pre-leaching assisted solvent extraction method for oil sand or oil sludge containing heavy crude oil, comprising the following steps:

[0034] Mixing the oil-containing solid material with a pre-leaching agent to perform pre-leaching to obtain a solid-liquid mixture; the oil-containing solid material is oil sand or oil sludge containing heavy crude oil; the pre-leaching agent comprises aromatic hydrocarbon; the boiling point of the aromatic hydrocarbon is < 150℃;

[0035] Mixing the solid-liquid mixture with a first extraction agent to perform first extraction, and then performing solid-liquid separation to obtain a solid phase and a liquid phase; the first extraction agent comprises cycloalkane; the boiling point of the first extraction agent is < 100℃; the solid-liquid separation comprises standing or centrifugation; the standing time is 5-40 min; the centrifugation speed is 300-1000 rpm, and the centrifugation time is 3-10 min.

[0036] The present application mixes the oil-containing solid material with a pre-leaching agent to perform pre-leaching to obtain a solid-liquid mixture.

[0037] In the present application, the oil-containing solid material is oil sand or oil sludge containing heavy crude oil; the oil phase asphaltene content of the oil-containing solid material is preferably ≥ 10wt%, and further preferably 10-62wt%.

[0038] The method provided by the present application can process oil-containing solid materials with extremely high asphaltene content (up to 62wt%), while ordinary solvent extraction has limited effect on the processing of oil-containing solid materials with high asphaltene content.

[0039] In the present application, the pre-extraction agent comprises aromatic hydrocarbon; the boiling point of the aromatic hydrocarbon is < 150℃; the aromatic hydrocarbon preferably comprises one or more of benzene, toluene and xylene. In the present application, the mass ratio of the oil-bearing solid substance to the pre-extraction agent is preferably 1:(0.5-3), further preferably 1:(0.8-2.5), and more preferably 1:(1.2-2.2).

[0040] In the present application, the pre-extraction is preferably carried out under stirring, the stirring speed is preferably 200-1000 rpm, further preferably 300-800 rpm, and more preferably 400-600 rpm; the stirring time is preferably 10-60 min, further preferably 15-45 min, and more preferably 20-35 min. In the present application, the pre-extraction temperature is preferably room temperature. The use of a small amount of aromatic hydrocarbon in the present application can extract and disperse the asphaltenes in the oil sludge / oil sand into the solvent system, which cannot be achieved by using mixed solvents.

[0041] In the present application, when the oil phase asphaltene content of the oil-bearing solid substance is ≥ 30wt%, the pre-extraction is preferably further preceded by mixing the oil-bearing solid substance with a pre-extraction agent and carrying out pre-extraction.

[0042] In the present application, the pre-extraction agent preferably comprises naphthenes, and the boiling point of the pre-extraction agent is preferably < 100℃; the naphthenes preferably comprise cyclohexane and / or cyclopentane. In the present application, the mass ratio of the oil-bearing solid substance to the pre-extraction agent is preferably 1:(1-5), further preferably 1:(1.2-4.5), and more preferably 1:(2-4); the pre-extraction is preferably carried out under stirring, the stirring speed is preferably 200-1000 rpm, further preferably 300-800 rpm, and more preferably 400-600 rpm; the stirring time is preferably 10-60 min, further preferably 15-45 min, and more preferably 20-35 min. In the present application, the pre-extraction temperature is preferably room temperature. In the present application, the pre-extraction is preferably followed by solid-liquid separation; the solid-liquid separation preferably comprises standing or centrifugation; the standing time is preferably 5-40 min, further preferably 10-30 min, and more preferably 15-25 min; the centrifugation speed is preferably 300-1000 rpm, and the time is preferably 3-10 min. The mixing of the oil-bearing solid substance and the pre-extraction agent in the present application for pre-extraction can reduce the amount of subsequent pre-extraction agent.

[0043] After obtaining the solid-liquid mixture, the solid-liquid mixture is mixed with a first extraction agent in the present application to carry out first extraction, and solid-liquid separation to obtain a solid phase and a liquid phase.

[0044] In the present application, the first extractant comprises cycloalkane; the boiling point of the first extractant is < 100℃; the cycloalkane preferably comprises cyclohexane and / or cyclopentane. In the present application, the mass of the solid-liquid mixture is preferably 1:(0.5-3), further preferably 1:(0.8-2.5), more preferably 1:(1.2-2.2) relative to the mass of the first extractant, based on the mass of the oil-containing solid material. In the present application, the first extraction is preferably carried out under stirring, the stirring speed is preferably 200-1000 rpm, further preferably 300-800 rpm, more preferably 400-600 rpm; the stirring time is preferably 10-60 min, further preferably 15-45 min, more preferably 20-35 min. In the present application, the temperature of the first extraction is preferably room temperature. The use of cycloalkane instead of n-alkane in the first extraction of the present application is because the addition of n-alkane will quickly cause the aggregation of asphaltene, which will cause the asphaltene dispersed from the oil sludge / oil sand into the solvent during the aromatic pre-leaching to quickly precipitate from the solvent system back to the surface of the solid, and the separation is not timely, so the purpose of oil-solid separation cannot be achieved.

[0045] In the present application, the solid-liquid separation comprises standing or centrifugation. In the present application, the standing time is 5-40 min, preferably 10-30 min, more preferably 15-25 min; the centrifugation speed is 300-1000 rpm, preferably 400-800 rpm, further preferably 500-700 rpm; the centrifugation time is preferably 3-10 min, further preferably 4-7 min. Since the main purpose of adding aromatic hydrocarbon in pre-leaching is to extract dispersed asphaltene, and the amount of added aromatic hydrocarbon is small, the first extraction by adding cycloalkane in the present application can extract more oil phase; in addition, the addition of cycloalkane during the first extraction can reduce the concentration of crude oil (asphaltene) in the extractant, which is conducive to more complete separation of crude oil and solid particles.

[0046] In the present application, when the oil phase asphaltene content of the oil-containing solid material is ≥10 wt% and < 30 wt%, after the first extraction, the solid-liquid separation obtains a solid phase and a liquid phase, and further comprises mixing the solid phase with a second extractant to perform a second extraction.

[0047] In this invention, the second extractant preferably comprises cycloalkanes, and the boiling point of the second extractant is preferably <100°C. In this invention, the mass of the solid phase is preferably based on the mass of the oil-containing solid material, and the mass ratio of the solid phase to the second extractant is preferably 1:(1-3), more preferably 1:(1.5-2.5); the second extractant preferably comprises cyclohexane and / or cyclopentane. In this invention, the second extraction is preferably carried out under conditions of repeated shaking or stirring; the repeated shaking time is preferably 10-30 s, more preferably 15-25 s; the stirring speed is preferably 200-1000 rpm, more preferably 300-800 rpm, more preferably 400-600 rpm; the stirring time is preferably 2-30 min, more preferably 5-25 min, more preferably 10-20 min. In this invention, the temperature of the second extraction is preferably room temperature. In an embodiment of this invention, manual repeated shaking is specifically used. This invention, through the second extraction, can remove the floating oil remaining on the solid surface after solid-liquid separation, thereby reducing the residual oil content in the solid phase.

[0048] Figure 1 This is a schematic diagram of the pre-extraction auxiliary solvent extraction process of the present invention. Figure 1 As shown, the present invention mixes oily solids with a pre-extracting agent for pre-extraction to obtain a solid-liquid mixture; the solid-liquid mixture is then mixed with an extractant (i.e., the first extractant) for a first extraction: the heavy crude oil in the solid is extracted into the liquid phase. After solid-liquid separation, the solid phase is dried after a second extraction, with a residual oil content of less than 1 wt%. The liquid phase can be fractionated to recover the extractant for recycling, while simultaneously obtaining recovered crude oil.

[0049] To further illustrate the present invention, the pre-leaching assisted solvent extraction method for oil sands or sludge containing heavy crude oil provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0050] In the embodiments and comparative examples of the present invention, the mass of the oil sand or oil sludge is 1 part, and the amount of solvent used is based on this.

[0051] Example 1

[0052] Taking an Indonesian oil sand (initial oil content of 36.22 wt% and bituminous content of 62.18 wt%) as an example, the oil sand was mixed with cyclohexane at a solid-liquid ratio of 1 part: 3 parts (mass ratio) for pre-extraction. The mixture was stirred magnetically at 500 rpm for 30 min, and then allowed to stand for 15 min for solid-liquid separation to obtain the first solid phase and the first liquid phase.

[0053] To the first solid phase, 0.5 parts of toluene was added, and pre-extraction was carried out by stirring at a speed of 500 rpm for 10 min to obtain a solid-liquid mixture;

[0054] To the solid-liquid mixture, 2.5 parts of cyclohexane was added, and first extraction was continued by stirring at a speed of 500 rpm for 10 min, and then solid-liquid separation was carried out by standing for 15 min to obtain a second solid phase and a second liquid phase; the second solid phase was placed in an oven for drying treatment at a temperature of 90℃ for 60 min, and then the residual oil rate of the treated solid phase was measured by the Dean-Stark method. Figure 2 The schematic diagram of the Dean-Stark extraction device of the present application is shown in FIG. 1.

[0055] Comparative Examples 1-3

[0056] Single solvent multistage extraction was used, and the solvents of Comparative Examples 1-3 were n-heptane, cyclohexane and toluene, respectively; the operation conditions were consistent with the pre-extraction conditions in Example 1 and repeated twice (i.e. oil sand and single solvent were mixed at a mass ratio of 1 part:3 parts, and two-stage extraction was carried out).

[0057] The pre-extraction auxiliary solvent extraction of Example 1 was compared with the single solvent multistage extraction of Comparative Examples 1-3, and the residual oil rate results are shown in Table 1.

[0058] Table 1 Residual oil rate results of treated solid phase of Example 1 and Comparative Examples 1-3

[0059]

[0060] As can be seen from Table 1, the pre-extraction auxiliary solvent extraction can make the residual oil rate of the solid phase less than 1wt%, which meets the requirements of the local standard DB61 / T1025-2016 "Control Limits for Disposal and Utilization of Oily Sludge". At the same time, the effect of the pre-extraction auxiliary solvent extraction is obviously better than that of the single solvent multistage extraction. In terms of the total amount of solvent used, the pre-extraction auxiliary solvent extraction uses 0.5 parts of toluene + 5.5 parts of cyclohexane to reduce the residual oil rate of the solid phase to 0.94wt%, which is close to the extraction effect (0.75wt%) of 6 parts of toluene in single solvent extraction. In the case of greatly reducing the amount of toluene, and without increasing the total amount of solvent used, an excellent extraction effect is achieved.

[0061] Examples 2-5

[0062] Taking a certain Indonesian oil sand (initial oil content of 36.22wt%, asphaltene content of 62.18wt%, and main mineral component of calcite) as an example, the oil sand was mixed with cyclohexane at a solid-liquid ratio of 1 part:3 parts (mass ratio) for pre-extraction, and magnetic stirring was carried out at a speed of 500 rpm for 30 min, and then solid-liquid separation was carried out by standing for 15 min to obtain a first solid phase and a first liquid phase;

[0063] Example 2-5 respectively added 0.5 parts, 1 part, 1.5 parts, 2 parts of toluene to the first solid phase, pre-extracted by stirring at a speed of 500 rpm for 10 min to obtain a solid-liquid mixture;

[0064] Examples 2-5 respectively added 2.5 parts, 2 parts, 1.5 parts, 1 part of cyclohexane to the solid-liquid mixture, continued to extract at a speed of 500 rpm for 10 min, then separated the solid and liquid after standing for 15 min to obtain a second solid phase and a second liquid phase; the second solid phase was placed in an oven for drying treatment, the temperature was 90°C, and the time was 60 min, then the residual oil rate of the treated solid phase was measured by Dean-Stark method. Figure 3 The photos of oil sands before and after pre-extraction auxiliary solvent extraction for Example 5 (mass ratio of toluene to cyclohexane = 2:1). As can be seen from the figure, the Indonesian oil sands before solvent extraction present black lumps, and the surface is covered with a layer of crude oil; after solvent extraction, it presents the soil yellow color of gravel itself, indicating that the crude oil covering the surface of the oil sands is removed by extraction.

[0065] Comparative Examples 4-7

[0066] The mixed solvent extraction was used, and the difference between the mixed solvent extraction and Examples 2-5 was that the same amount of toluene in the pre-extraction stage and cyclohexane added in the subsequent first extraction were mixed with the first solid phase at the same time, and stirred at a speed of 500 rpm for 20 min, then the solid and liquid were separated, and the rest of the steps were consistent with Examples 2-5.

[0067] The results of pre-extraction auxiliary solvent extraction and mixed solvent extraction of Examples 2-5 were compared, and the residual oil rate results are shown in Table 2.

[0068] Table 2 Residual oil rate results of treated solid phase of Examples 2-5 and Comparative Examples 4-7

[0069]

[0070] As can be seen from Table 2, the residual oil rate of the solid phase can be less than 1wt% by pre-extraction auxiliary solvent extraction, which meets the requirements of the local standard DB61 / T1025-2016 "Control Limits for Oily Sludge Disposal and Utilization". At the same time, the effect of pre-extraction auxiliary solvent extraction is obviously better than that of mixed solvent extraction; under the same conditions of solvent type, solvent amount, stirring time, stirring speed, etc., the effect of pre-extraction is better than that of direct mixed solvent extraction, especially in the case of less toluene, which shows the innovation and necessity of the pre-extraction method.

[0071] Examples 6-9

[0072] Take a certain Indonesian oil sand (initial oil content of 27.62wt%, asphaltene content of 28.69wt%, and main mineral component of calcite) as an example, 0.5 parts, 1 part, 1.5 parts, and 2 parts of toluene were added to 1 part of the oil sand in Examples 6-9 respectively, and pre-extraction was carried out by stirring at a speed of 500 rpm for 15 min to obtain a solid-liquid mixture;

[0073] 2.5 parts, 2 parts, 1.5 parts, and 1 part of cyclohexane were added to the solid-liquid mixture in Examples 6-9 respectively, and first extraction was continued by stirring at a speed of 500 rpm for 15 min, followed by standing for 10 min for solid-liquid separation to obtain a first solid phase and a first liquid phase;

[0074] 2 parts of cyclohexane were added to the first solid phase and second extraction was carried out by manual shaking, followed by standing for 10 min for solid-liquid separation to obtain a second solid phase and a second liquid phase; the second solid phase was placed in an oven for drying treatment at a temperature of 90°C for 60 min, and then the residual oil rate of the treated solid phase was measured by the Dean-Stark method. The results are shown in Table 3. Figure 4 The photos of the oil sand before and after pre-extraction assisted solvent extraction in Example 9 (mass ratio of toluene to cyclohexane = 2:1). As can be seen from the figure, the Indonesian oil sand before solvent extraction presents black clumps, and the surface is covered with a layer of crude oil; after solvent extraction, it presents the earthy yellow color of gravel itself, indicating that the crude oil covering the surface of the oil sand has been extracted and removed.

[0075] Table 3 Residual oil rate of treated solid phase in Examples 6-9

[0076]

[0077] As can be seen from Table 3, the residual oil rate of the solid phase can be reduced to less than 1wt% by pre-extraction assisted solvent extraction, which meets the requirements of the local standard DB61 / T1025-2016 "Control Limits for Disposal and Utilization of Oil-containing Sludge".

[0078] Examples 10-12

[0079] Take a certain Canadian oil sand (initial oil content of 14.61wt%, asphaltene content of 16.99wt%, and main mineral component of quartz sand, but also some other minerals) as an example, 0.5 parts, 1 part, and 2 parts of dimethylbenzene were added to 1 part of the oil sand in Examples 10-12 respectively, and pre-extraction was carried out by stirring at a speed of 500 rpm for 20 min to obtain a solid-liquid mixture;

[0080] 2.5 parts, 2 parts, and 1 part of cyclopentane were added to the solid-liquid mixture in Examples 10-12 respectively, and first extraction was continued by stirring at a speed of 500 rpm for 20 min, followed by standing for 5 min for solid-liquid separation to obtain a first solid phase and a first liquid phase;

[0081] The second extraction was performed by adding 2 parts of cyclopentane to the first solid phase and stirring at a speed of 500 rpm for 5 min, followed by standing for 5 min for solid-liquid separation to obtain a second solid phase and a second liquid phase; the second solid phase was placed in an oven for drying treatment at a temperature of 90 °C for 60 min, and then the residual oil rate of the treated solid phase was measured by the Dean-Stark method. The results of the residual oil rate are shown in Table 4. Figure 5 The photos of oil sands before and after pre-leaching assisted solvent extraction for Example 12 (mass ratio of xylene to cyclopentane = 2:1); as can be seen from the figure, the Canadian oil sands before solvent extraction appear as black lumps, and the surface is tightly covered with a layer of crude oil; after solvent extraction, it appears grayish white, indicating that the crude oil covering the surface of the oil sands has been removed by extraction.

[0082] Table 4 Results of residual oil rate of treated solid phase for Examples 10-12

[0083]

[0084] As can be seen from Table 4, the residual oil rate of the solid phase can be reduced to less than 1 wt% by pre-leaching assisted solvent extraction, which meets the requirements of the local standard DB61 / T1025-2016 “Control Limits for Disposal and Utilization of Oily Sludge”.

[0085] Examples 13-16

[0086] Taking a simulated oily sludge (initial oil content of 20 wt%, asphaltene content of 16.01 wt%) as an example, 0.5 parts, 1 part, 2 parts, and 2.5 parts of benzene were added to 1 part of the oily sludge in Examples 13-16, respectively, and pre-leaching was performed by stirring at a speed of 500 rpm for 30 min to obtain a solid-liquid mixture;

[0087] In Examples 13-16, 2.5 parts, 2 parts, 1 part, and 0.5 parts of cyclopentane were added to the solid-liquid mixture, respectively, and first extraction was continued by stirring at a speed of 500 rpm for 20 min, followed by standing for 5 min for solid-liquid separation to obtain a first solid phase and a first liquid phase;

[0088] Second extraction was performed by adding 2 parts of cyclopentane to the first solid phase and stirring at a speed of 500 rpm for 15 min, followed by standing for 5 min for solid-liquid separation to obtain a second solid phase and a second liquid phase; the second solid phase was placed in an oven for drying treatment at a temperature of 90 °C for 60 min, and then the residual oil rate of the treated solid phase was measured by the Dean-Stark method. The results of the residual oil rate are shown in Table 5. Figure 6The photos of the oil sludge before and after the pre-leaching assisted solvent extraction of Example 15 (mass ratio of benzene to cyclopentane = 2:1) are shown in the figure. As can be seen from the figure, the simulated oil sludge before solvent extraction presents black lumps, and the surface is tightly covered with a layer of crude oil; after solvent extraction, it presents white quartz sand particles, indicating that the crude oil covering the surface of the oil sludge is removed by extraction.

[0089] Table 5 Results of solid phase residual oil rate after treatment of Examples 13-16

[0090]

[0091]

[0092] By pre-leaching assisted solvent extraction, the solid phase residual oil rate can be less than 1wt%, meeting the requirements of the local standard DB61 / T1025-2016 "Control Limits for Disposal and Utilization of Oil-containing Sludge".

[0093] Although the above examples make a detailed description of the present application, it is only a part of the embodiments of the present application, not all the embodiments, and other embodiments can be obtained according to the present embodiments without creativity, which all belong to the protection scope of the present application.

Claims

1. A pre-extraction assisted-solvent extraction process for oil sands or oil sludge containing heavy crude oil, characterized in that, The method comprises the following steps: The oil-containing solid material is mixed with a pre-extraction agent to perform pre-extraction, to obtain a solid-liquid mixture; the oil-containing solid material is oil sand or oil sludge containing heavy crude oil, the oil phase asphaltene content of the oil-containing solid material is ≥10wt%; the pre-extraction agent is one or more of benzene, toluene and xylene, the mass ratio of the oil-containing solid material to the pre-extraction agent is 1:(0.5-3); when the oil phase asphaltene content of the oil-containing solid material is ≥30wt%, the method further comprises mixing the oil-containing solid material with a pre-extraction agent to perform pre-extraction, and then performing solid-liquid separation, and the obtained solid phase is subjected to pre-extraction; The pre-extraction agent is cyclohexane and / or cyclopentane; The solid-liquid mixture is mixed with a first extraction agent to perform first extraction, and then solid-liquid separation is performed to obtain a solid phase and a liquid phase; the first extraction agent is cyclohexane and / or cyclopentane; the mass of the solid-liquid mixture is based on the mass of the oil-containing solid material, the mass ratio of the solid-liquid mixture to the first extraction agent is 1:(0.5-3); the solid-liquid separation after the first extraction comprises standing or centrifugation; the standing time is 5-40min; the centrifugation speed is 300-1000rpm, and the centrifugation time is 3-10min; When the oil phase asphaltene content of the oil-containing solid material is ≥10wt% and <30wt%, the method further comprises mixing the solid phase obtained after the solid-liquid separation after the first extraction with a second extraction agent to perform second extraction; the second extraction agent is cyclohexane and / or cyclopentane.

2. The pre-leaching assisted solvent extraction process according to claim 1, characterized in that, The mass ratio of the oil-containing solid material to the pre-extraction agent is 1:(1-5).

3. The pre-leaching assisted solvent extraction process of claim 1, wherein, The mass of the solid phase in the second extraction is based on the mass of the oil-containing solid material, and the mass ratio of the solid phase obtained after the solid-liquid separation after the first extraction to the second extraction agent is 1:(1-3). The mass of the solid phase in the second extraction is based on the mass of the oil-containing solid material, and the mass ratio of the solid phase obtained after the solid-liquid separation after the first extraction to the second extraction agent is 1:(1-3).

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