RU2649387C2 - Method for selective deasphalting of heavy feedstock - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: extraction is carried out with a mixture of at least one polar solvent and at least one apolar solvent so as to obtain an asphalt phase and a deasphalted oil DAO phase, the ratios of said polar solvent to said apolar solvent of the solvent mixture being controlled depending on the properties of the feedstock and the required asphalt yield, said process being carried out under subcritical conditions for the solvent mixture. Polar solvent used is selected from pure aromatic or naphthene-aromatic solvents, the polar solvents comprising hetero-elements or mixtures thereof or fractions from distillation with a high aromatic content such as fractions from FCC (Fluid Catalytic Cracking), coal distillation by-products, biomass or biomass / coal mixture, the apolar solvent used comprising a solvent consisting of a saturated hydrocarbon having a carbon number greater than or equal to 2, preferably from 2 to 9, extraction temperature from 90 to 320°C and pressure - from 0.1 to 6 MPa.

EFFECT: present invention relates to a process for selective deasphalting of a heavy feedstock by means of single-step liquid extraction in an extraction medium.

17 cl, 3 dwg, 1 ex

Description

Technical field

The present invention relates to the field of refining crude oil. In particular, the present invention relates to a method for the selective deasphalting of heavy feedstocks, especially residues from the distillation of crude oil, by liquid extraction.

State of the art

Residues from the distillation of crude oil contain such molecular structures as resins, maltens and asphaltenes, aromatic polyaromatic products, organic products of high molecular weight, with a high content of S, N and O heteroatoms with which metals such as nickel, vanadium form complexes ... These molecular structures are a major inconvenience in oil refining processes. Indeed, the performance of valorization and conversion methods is faced with limitations, which are mainly due to the presence of these so-called refractory molecular structures.

Most often, residues from the distillation of crude oil are pre-treated with deasphalting, well known to the specialist. The principle of deasphalting is based on dividing the oil residue into two phases: i) a phase called “deasphalted oil”, also called “matrix oil” or “oil phase” or DAO (De-Asphalted Oil in English-German terminology), which can be suitable for processing through various cleaning methods; and ii) a phase called “asphalt” or sometimes “pitch” (in English-German terminology) containing the refractory molecular structures described above. Asphalt, due to its low quality and changing state, which can change from a solid phase, then to a pasty and, finally, to a liquid phase, depending on temperature conditions, is a harmful product for technological treatment schemes, the amount of which should be minimized.

Such deasphalting, referred to in the following description as conventional deasphalting, is usually carried out using a paraffin type solvent. For example, US Pat. Nos. 4,305,812 and 4,452,216 describe deasphalting as countercurrent extraction in a column with several solvents of increasing polarity injected at different column heights.

US 7857964 describes the effect of the type of paraffin solvent used in the deasphalting method on the performance of hydrotreating residues.

US 2008/149534 refers to a cascade deasphalting process, in particular a two-stage process. The first paraffin solvent with 5 or 7 carbon atoms (C5 or C7) is used to extract asphalt. The collected deasphalted DAO oil is then treated with another paraffin solvent containing less carbon (C3 or C4) to separate the resin-containing fraction from the matrix oil.

The solutions proposed at a certain level are based on conventional deasphalting, which by its principle has limitations on output and flexibility in comparison with the processing provided for oil residues. The disadvantage of using solvents or a mixture of paraffin type solvents in conventional deasphalting is the restriction on the yield of DAO deasphalted oil, the yield being increased with the molecular weight of the solvent (to solvent C6 / C7), after which it reaches a limit value equal to the threshold inherent in each raw material and each solvent .

The subject of the present invention is the elimination of the aforementioned limitations of conventional deasphalting through the use of a selective deasphalting method that overcomes the threshold of dependence on the paraffin solvent used. The proposed solution allows you to adjust the properties of the raw materials in the form of residues before they are received for processing, while maximizing the final yield of deasphalted DAO oil.

The applicant proposes a method for the selective deasphalting of heavy raw materials by means of a single-stage liquid extraction in an extraction medium, said extraction being carried out using a mixture of at least one polar solvent and at least one apolar solvent, the ratios of the said polar solvent and the said apolar solvent being regulated depending on the properties of the feedstock and the required yield on asphalt, and the above method is carried out under conditions temperatures and pressures determined for the solvent mixture.

Subject of invention

The present invention relates to a method for the selective deasphalting of heavy raw materials through a single-stage liquid extraction in an extraction medium, said extraction being carried out using a mixture of at least one polar solvent and at least one apolar solvent, so as to obtain an asphalt phase and a deasphalted phase DAO oils, and the ratios of the named polar solvent and the named apolar solvent of the solvent mixture are regulated depending on oystv feed raw material and the desired output on asphalt, said method is performed in subcritical conditions for the solvent mixture.

Advantageously according to the invention, the ratio of the polar solvent in the mixture of the polar solvent and the apolar solvent is from 0.1 to 99.9%.

Advantageously according to the invention, the polar solvent used is selected from pure aromatic or naphthenaromatic solvents, the polar solvents containing heteroelements or mixtures thereof, or distillation fractions with a high content of aromatic compounds, such as fractions from FCC (Fluid Catalytic Cracking), side fractions of coal, biomass or biomass / coal mixtures.

Advantageously according to the invention, the apolar solvent used comprises a solvent consisting of saturated hydrocarbon (s) with a carbon number greater than or equal to 2, preferably from 2 to 9.

Advantageously according to the invention, the volumetric ratio of the mixture of polar and apolar solvents to the weight of the feedstock is from 1/1 to 10/1, expressed in liters per kilogram.

Advantageously according to the invention, the deasphalted DAO oil recovered at least partially with a mixture of polar and apolar solvent in the extraction step is subjected to a separation step in which the deasphalted DAO oil is separated from the solvent mixture under supercritical or subcritical conditions.

Description of drawings

FIG. 1 is a deasphalting scheme comprising the selective deasphalting method of the invention.

FIG. 2 is a deasphalting scheme comprising the selective deasphalting method of the invention, which uses a diluent whose boiling point is lower than or equal to the boiling point of a polar solvent from the solvent of the invention.

FIG. 3. illustrates the variation in the yield of DAO deasphalted oil depending on the type of precipitating solvent for RA AM / RSV AL feedstock under conventional deasphalting conditions and under the conditions of the invention. '

DETAILED DESCRIPTION OF THE INVENTION

In the following description and in the foregoing description, the expression “solvent mixture of the invention” is meant to mean a mixture of at least one polar solvent and at least one apolar solvent according to the invention.

The method according to the invention is carried out in one step and includes bringing into contact the heavy raw materials to be deasphalted with a mixture of at least one polar solvent and at least one apolar solvent in the extraction medium. The ratios of the polar solvent and apolar solvent are regulated, on the one hand, depending on the properties of the feedstock and the required extraction coefficient, on the other hand, depending on the following schemes and valorization methods, such as hydrocracking, hydrotreating, hydroconversion, catalytic cracking, thermal cracking .

The method according to the invention is a method of selective deasphalting, which allows you to go further in maintaining the solubility in matrix oil of all or part of the molecular structures called difficult to process. It allows you to go further in maintaining the solubility in matrix oil of all or part of the polar structures of heavy resins and asphaltenes, which are the main components of the asphalt phase. The invention thus allows one to choose which type of polar structure remains soluble in the matrix oil. In this regard, the method of selective deasphalting according to the invention allows to selectively extract only some part of this asphalt, i.e. the most polar and most difficult to process structures in the methods of conversion and purification.

The asphalt recovered by the method of the invention is the last asphalt, consisting mainly of polyaromatic or heteroatom difficult to process molecular structures. The asphalt yield is correlated with the DAO oil yield according to the following equation:

Asphalt output = 100- [oil output DAO]

According to the invention, the feedstock used is selected from a feedstock of petroleum origin such as crude oil, or a residual fraction from the distillation of crude oil, such as atmospheric residue or vacuum residue from the distillation of so-called conventional crude oil (degree APN> 20 ° C), heavy reservoir oil (degree APN from 10 to 20 ° C) or superheavy reservoir oil (degree APN <10 ° C). Said feedstock may also be a residual fraction from any pre-treatment step, such as, for example, hydrocracking, hydrotreating or thermal cracking of one of these types of crude oil or one of these atmospheric residues or one of these vacuum residues. The named feed may also be a residual fraction from direct liquefaction of coal (atmospheric residue or vacuum residue) with or without hydrogen, with or without a catalyst, whatever the method used, or a residual fraction from direct liquefaction of only lignocellulosic biomass or in a mixture with coal and / or residual oil fraction, with or without hydrogen, with or without a catalyst, whatever the method used.

The method according to the invention can be carried out in an extraction column or extractor, preferably in a mixer-settler. The method according to the invention is carried out by means of a single-stage liquid extraction. Preferably, the solvent mixture of the invention is fed into the extraction column or mixer-settler at two different levels.

According to the method of the invention, liquid extraction is used under subcritical conditions for said solvent mixture, i.e. at temperatures below the critical temperature of the solvent mixture. The extraction temperature is preferably from 50 to 350 ° C, preferably from 90 to 320 ° C, even more preferably from 100 to 310 ° C, even more preferably from 120 to 310 ° C, even more preferably from 150 to 310 ° C, and the pressure is preferably from 0.1 to 6 MPa, preferably from 2 to 6 MPa.

The volume ratio of the solvent mixture of the invention (polar solvent volume + apolar solvent volume) to the weight of the feed is usually from 1/1 to 10/1, preferably 2/1 to 8/1, expressed in liters per kilogram.

The mixture of selective deasphalting solvents of the invention is a mixture of at least one polar solvent and at least one apolar solvent.

The polar solvent used in the method according to the invention can be selected from pure aromatic or naphthenaromatic solvents, the polar solvents containing heteroelements or mixtures thereof. The aromatic solvent is preferably selected from monoaromatic hydrocarbons, preferably only from benzene, toluene or xylene, or a mixture thereof; diaromatic or polyaromatic; aromatic naphthenic hydrocarbons, such as tetralin or indan; heteroatomic aromatic hydrocarbons (enriched with oxygen, nitrogen, sulfur), or any other family of compounds that are more polar than saturated hydrocarbons, such as dimethyl sulfoxide (DMSO), dimethylformamide (DMF), tetrahydrofuran (THF). The polar solvent used in the process of the invention may be a fraction from a high aromatics distillation fraction. The high aromatic distillation fractions of the invention can be, for example, FCC (Fluid Catalytic Cracking) fractions such as heavy gasoline or LCO (light cycle oil) LCO. Also referred to are side fractions from coal distillation, biomass or biomass mixtures / coal, possibly with residual petroleum feedstock after thermochemical conversion with or without hydrogen, with or without a catalyst, Preferably, the polar solvent used is a pure monoaromatic hydrocarbon or mixed with an aromatic hydrocarbon.

The apolar solvent used in the method of the invention is preferably a solvent consisting of saturated hydrocarbon (s) with a carbon number greater than or equal to 2, preferably from 2 to 9. These solvents are used in pure form or in a mixture (for example, a mixture of alkanes and / or cycloalkanes, or light fractions from the distillation of oil such as naphtha).

Advantageously according to the invention, the boiling point of the polar solvent from the solvent mixture of the invention is higher than the boiling point of the apolar solvent.

In combination with the temperature and pressure conditions of the extraction according to the invention, changing the ratio between the polar and apolar solvent creates a true key opportunity for regulating the method of selective deasphalting according to the invention. For a given feedstock, the higher the ratio and / or polarity inherent in the polar solvent in the solvent mixture, the higher the yield on deasphalted oil, with some of the polar structures of the feed remaining soluble and / or dispersible in the DAO oil phase. As a result of a decrease in the ratio of polar solvent in the mixture, the amount of collected asphaltene phase increases. Thus, the method according to the invention allows to selectively recover, regardless of the feedstock, the asphalt phase, called the latter, with a high content of impurities and difficult to valorize compounds, leaving at least part of the polar structures of heavy resins and asphaltenes soluble in matrix oil which are the least polar, not representing difficulties for valorization.

According to the invention, the ratio of the polar solvent in the mixture of the polar solvent and the apolar solvent is from 0.1 to 99.9%, preferably from 0.1 to 95%, preferably from 1 to 95%, more preferably from 1 to 90%, even more preferably from 1 to 85% and very preferably from 1 to 80%.

The ratio of the polar solvent in the mixture of polar and apolar solvent depends on the required selectivity, i.e. from the desired output for DAO deasphalted oil. This depends on the objectives of the technological scheme, within which the method according to the invention is used, and market demands.

The ratio of the polar solvent in the mixture of polar and apolar solvent also depends on the type of feedstock, and the molecular structures that make up the feedstock vary from one feedstock to another. Not all downloads have the same recyclability. The fraction of recoverable asphalt is not necessarily the same depending on the type of raw material.

The type of raw material also depends on its origin: petroleum, coal or biomass.

According to the method of the invention, the deasphalted oil recovered at least partially with the solvent mixture of the invention in the extraction step can advantageously undergo a separation step in which the deasphalted DAO oil is separated from the solvent mixture of the invention, or at least a separation step, in which the deasphalted DAO oil is separated only from the apolar solvent, under supercritical or subcritical solvent conditions for a mixture of solvents, preferably in super critical conditions. At the exit from this stage, the DAO deasphalted oil is preferably sent to a light distillation unit before recovery. The mixture of polar and apolar solvents is predominantly recycled after separation, and the apolar / polar ratio is checked in the stream and adjusted, if necessary, using make-up tanks, containing separately polar and apolar solvents.

The separated asphalt phase (or asphalt) of the extraction step of the invention is preferably in a liquid state and is usually diluted, at least partially, with a portion of the solvent mixture of the invention, the amount of which can reach up to 200%, preferably from 30 to 80% of the asphalt discharged. Asphalt, recovered at least partially with a mixture of polar and apolar solvents, may be mixed with at least one diluent at the outlet of the extraction step so as to facilitate its release. The diluent used may be any solvent or solvent mixture capable of dissolving or dispersing asphalt. The diluent may be a polar solvent selected from monoaromatic hydrocarbons, preferably benzene, toluene or xylene; diaromatic or polyaromatic; aromatic naphthenic hydrocarbons, such as tetralin or indan; heteroatomic aromatic hydrocarbons; polar solvents with a molecular weight corresponding to boiling points, for example, between 200 ° C and 600 ° C, such as LCO (light cycle oil from FCC), HCO (Heavy cycle oil from FCC), sludge from FCC, HCGO (heavy coker gas-oil), or an aromatic extract or extra-aromatic fraction extracted from the oil chain, the VGO fraction from the conversion of residual fractions and / or coal and / or biomass.

The volumetric ratio of the diluent to the mass of asphalt is determined so that the mixture can be easily discharged.

According to the first embodiment of the method according to the invention, when the boiling point of the polar solvent of the solvent mixture according to the invention is lower than the boiling point of the diluent, the asphalt phase mixed with the diluent and at least partially with the solvent of the invention preferably undergoes a separation step in which the solvent of the invention is separated from mixtures of asphalt phase and thinner. Advantageously, the solvent of the invention obtained at the outlet of this step is recycled to the extraction step of the process of the invention, preferably in a mixture with a solvent separated from the deasphalted DAO oil.

The mixture of the asphalt phase and the separated diluent may be subjected to a separation step in which the asphalt phase is at least partially separated from the diluent. Advantageously, the diluent obtained at the outlet of this separation is recycled to the process of the invention for the discharge of asphalt into the extraction step of the invention.

According to a second embodiment of the method according to the invention, when the boiling point of the polar solvent of the solvent mixture according to the invention is higher than or equal to the boiling point of the diluent, the asphalt phase mixed with the diluent and at least partially the solvent mixture of the invention preferably undergo a preliminary separation step in which the asphalt phase separated from the diluent and the solvent mixture of the invention. After separation of the asphalt phase, the mixture of diluent and solvents coming from the solvent mixture of the invention preferably undergoes a separation step in which the diluent, polar solvent, and apolar solvent are individually separated.

According to a second embodiment of the method according to the invention, said separated thinner is advantageously recycled to the method according to the invention for the release of asphalt in the extraction step according to the invention.

According to the second variant of the method according to the invention, the polar solvent and the apolar solvent separated from the diluent are recycled to the extraction stage of the method according to the invention after they have been individually sent to the feed tanks located at the inlet of the extraction stage. These tanks are used as a reservoir for creating a mixture of polar and apolar solvents used in the extraction step of the invention and for controlling their ratios.

The method according to the invention has the advantage of significantly increasing the yield of DAO deasphalted oil over the entire range, including as yet not studied by conventional deasphalting. For a given raw material, the achieved yield on DAO deasphalted oil is at most 75% (extraction with normal heptane), the selective deasphalting according to the invention allows both polar and apolar solvent to be used by adjusting the ratio, providing a yield in the range of 75-99.9% deasphalted DAO oil.

The yield of deasphalted DAO oil by choice, whatever the feedstock, is preferably from 50 to 99.9%, preferably from 75 to 99.9%, more preferably from 80 to 99.9%.

The method according to the invention, due to its selectivity and its flexibility, allows to obtain an asphalt fraction with a yield on asphalt, which can be significantly lower than the yield that can be achieved by a conventional deasphalting method for a given raw material. The named asphalt yield is preferably from 1 to 50%, preferably from 1 to 25%, more preferably from 1 to 20%.

The present invention has the advantage of providing a double benefit, namely: i) improving the properties of the feedstock, providing easier and more perfect valorization, with ii) a controlled restriction of yield on asphalt.

Description of drawings

In the embodiment described in FIG. 1, preheated with furnaces and / or heat exchangers (not shown), the feedstock (1) is fed to an extraction unit (13), such as an extraction column, preferably a settling mixer. The polar solvent (3) and the apolar solvent (2) are mixed at the inlet to the mixer (10), fed from two recharge tanks, each filled individually with a polar solvent (tank 4) and an apolar solvent (tank 5). The solvent mixture is preferably fed to the extraction unit (13) at two different levels. At least a portion of the solvent mixture is sent via line 11 mixed with feedstock fed to the extraction unit (13) via line 1. At least another part of the solvent mixture is sent directly to the extraction unit (13) via line 12, in which extraction is carried out under the conditions defined above according to the invention.

At the exit from the extraction step, the recovered deasphalted DAO oil in the mixture, at least partially with the solvent mixture of the invention, is routed through line 15 to a separator (17), in which the deasphalted DAO oil is separated from the solvent of the invention (25). The named mixture is mainly separated in a separator under supercritical or subcritical conditions. After that, the DAO deasphalted oil is preferably sent to the light distillation unit or column (21) through line 20 before being removed via line 23. The solvent at the outlet of the light fractionation unit is sent to line 27 through line 24.

In FIG. 1, asphalt, also containing a solvent mixture according to the invention, is discharged from the extraction unit (13) as a liquid mixture or as a solid dispersed with a thinner supplied through a pipeline 14. Then, a mixture of asphalt, a solvent according to the invention and a thinner is supplied through a pipe 16 to a separator or a column for distillation of light fractions (18), in which, when the boiling point of the polar solvent of the solvent mixture according to the invention is lower than the boiling point of the thinner, asphalt and thinner are separated about solvent according to the invention. Asphalt and a diluent are recovered via line 19, and the solvent of the invention is directed to line 27 via line 26.

The solvent at the outlet of the separators (17, 18) and the unit for distillation of light fractions (21) is mainly recycled to the extraction method along line (27). The composition of the mixture of polar and apolar solvents is preferably checked in the stream using a densitometer or refractometer (28). The ratios of the polar solvent and the apolar solvent are regulated, if necessary, by feeding respectively the polar solvent and the apolar solvent, delivered from the feed tanks 4 and 5 via pipelines 6 and 7. The mixture selected in this way is predominantly averaged in a static type mixer (29) before being sent to mixer (10).

In FIG. 2 is a schematic diagram of an embodiment of the method of the invention in which the boiling point of the polar solvent of the mixture used to dissolve according to the invention is higher than or equal to the boiling point of the diluent. In this case, the asphalt is predominantly separated at the inlet of mixing the solvents of the invention and the diluent before separating each of the polar and apolar solvents from the diluent for optimal recycling. FIG. 2 contains the same conventions as FIG. 1, with the exception of the part regarding the separation of the solvent of the invention from asphalt and a diluent.

So in FIG. 2, a mixture of asphalt, a solvent according to the invention and a diluent separated from the extraction unit (13) is sent via line 16 to a separator (31), in which the asphalt is separated and recovered through line 32. After that, the solvent according to the invention and a diluent at the outlet of the separator ( 31) are sent to the separator (34) through a pipe 33, in which the diluent, polar solvent and apolar solvent are individually separated by pipelines 37, 35 and 36, respectively. The polar solvent and apolar solvent are returned from tvetstvenno in tanks for feed 4 and 5 (lines 35, 36). The separated diluent from the separator (34) returns via line 37 to line 14 supplying the diluent.

The need for recirculation of the diluent may depend on the valorization scheme of the selected asphalt, i.e. Valorization of liquefied or non-liquefied asphalt.

Advantageously by the method of the invention, asphalt extraction can be carried out in various ways.

In an embodiment, the asphalt is recovered in batches in solid form by means of two parallel drums, as in a coke recovery system (delayed coker in English-German terminology). Asphalt accumulates alternately in the drums and is removed mechanically by opening the containers.

Another embodiment is the curing of asphalt by flocculation in water. The collected asphalt is thus ready for transportation and / or storage.

In another embodiment of the method of the invention, asphalt is discharged from the extraction plant in the form of sludge. Solid asphalt is transported in this case by a fluid other than solvent and thinner. Separation of asphalt from said fluid is carried out by filtration. Preferably, at least one fluid is used that develops the dissolving power of asphalt under supercritical conditions. The separation of asphalt and fluid is subsequently carried out by placing mainly in subcritical or supercritical conditions.

Examples

Use feedstock consisting of 70 mass. % of the atmospheric residue of Arabian medium and 30 mass. % of Arabian light vacuum residue (RA AM / RSV AL) with the following characteristics:

The experiment was conducted in the laboratory.

The feedstock is deasphalted under the following conditions:

The resulting yields of DAO deasphalted oil

The change in the yield of DAO deasphalted oil depending on the type of precipitating solvent is shown in FIG. 3. In the case of a solvent containing 100% paraffin molecules with a carbon number lower than or equal to 7, the yield on DAO deasphalted oil reaches 94% for the feed used. This percentage corresponds to the normal deasphalting area. The addition of a polar solvent to the solvent allows this threshold to be exceeded. By changing the volume ratio of the polar solvent to the apolar solvent, the yields of DAO deasphalted oil reach from 94 to 99.9% under the conditions of the invention, therefore, asphalt yields reach from 0.1 to 6%.

Claims (20)

1. A method for the selective deasphalting of heavy raw materials through a single-stage liquid extraction in an extraction medium, said extraction being carried out using a mixture of at least one polar solvent and at least one apolar solvent so as to obtain an asphalt phase and a phase of deasphalted DAO oil, wherein the named polar solvent and the named apolar solvent of the solvent mixture are regulated depending on the properties of the feedstock and t ebuemogo output on asphalt, said method is performed in subcritical conditions for the solvent mixture, in which the polar solvent used is selected from pure aromatic or naphthenaromatic solvents, the polar solvents containing heteroelements or mixtures thereof, or fractions from distillation with a high content of aromatic compounds, such as fractions from FCC (Fluid Catalytic Cracking), side fractions from distillation of coal, biomass or biomass / coal mixtures, and in which the apolar solvent used contains a solvent consisting of a saturated hydrocarbon with a carbon number greater than or equal to 2, preferably from 2 to 9, and in which the extraction temperature is from 90 to 320 ° C, and the pressure is from 0.1 to 6 MPa. 2. The method according to claim 1, wherein said liquid extraction is carried out in an extraction column or in a settling mixer. 3. The method according to claim 1 or 2, in which the mixture of solvents is fed into the extraction column or into the mixer-settler at two different levels. 4. The method according to claim 3, in which the ratio of the polar solvent in the mixture of the polar solvent and the apolar solvent is from 0.1 to 99.9%. 5. The method according to claim 4, in which the volume ratio of the mixture of polar and apolar solvents to the mass of the feedstock is from 1/1 to 10/1, expressed in liters per kilogram. 6. The method according to claim 5, in which the feedstock is selected from raw materials of petroleum origin such as crude oil, atmospheric residue, type of vacuum residue from crude oil, called ordinary, heavy crude oil or superheavy crude oil, residual fraction from any pre-treatment method, such as hydrocracking, hydrotreating, thermal cracking of one of these types of crude oil or one of these atmospheric residues, or one of these vacuum residues, the residual fraction from the direct liquefaction of only lignocellulosic biomass or mixed with coal and / or residual oil fraction. 7. The method according to any one of claims 4 to 6, wherein the deasphalted DAO oil recovered at least partially with a mixture of polar and apolar solvents in the extraction step is subjected to a separation step in which the deasphalted DAO oil is separated from the solvent mixture or at least at least the separation stage, in which the deasphalted DAO oil is only separated from the apolar solvent under supercritical or subcritical conditions. 8. The method according to claim 7, in which the separated mixture of polar and apolar solvents is recycled to the extraction stage, and the amounts and ratios of polar and apolar solvents are checked in the stream and regulated, if necessary, by recharge tanks. 9. The method according to claim 8, in which the recovered asphaltic phase is mixed with at least one diluent for at least one dilution of the polar and apolar solvent at the outlet of the extraction stage for easier release. 10. The method according to claim 9, in which when the boiling point of the polar solvent of the mixture of polar and apolar solvents is lower than the boiling point of the diluent, the asphalt phase in the mixture with the diluent and at least partially the mixture of polar and apolar solvents undergo a separation stage in which the mixture of polar and apolar solvents are separated from the mixture of the asphalt phase and the diluent. 11. The method of claim 10, wherein the mixture of the asphalt phase and the diluent undergoes a separation step in which the asphalt phase is separated from the diluent. 12. The method according to claim 9, in which, when the boiling point of the polar solvent of the mixture of polar and apolar solvents is higher than or equal to the boiling point of the diluent, the asphalt phase in the mixture with the diluent and at least partially the mixture of polar and apolar solvents are subjected to separation stages, in which the asphalt phase is separated from the diluent and the mixture of polar and apolar solvents. 13. The method of claim 12, wherein the diluent and the mixture of polar and apolar solvents are subjected to a separation step, wherein the diluent, polar solvent and apolar solvent are individually separated. 14. The method according to claims 11 and 13, in which the thinner separated from the asphalt phase or separated from the polar solvent and from the apolar solvent, the thinner is recycled to the extraction stage. 15. The method according to claim 10, in which the mixture of polar and apolar solvents, separated from the mixture of the asphalt phase and diluent, is recycled to the extraction stage of the method according to the invention. 16. The method according to item 13, in which the individually separated polar solvent and apolar solvent are pre-sent to the tanks for recharge placed at the entrance of the extraction stage to create a mixture of polar and apolar solvents in the ratios used in the extraction stage. 17. The method according to PP.11 and 12, in which the extraction of the asphalt phase is carried out in a separate batch in solid form or flocculation in water, or in the form of sludge with at least one fluid.

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