JPS63112687A - Method of fractionating pitch - Google Patents

Abstract

PURPOSE:To fractionate a highly concentrated component for use as a starting material of a highly value-added carbon product which is insoluble in benzene and soluble in quinoline by making use of a simple apparatus through simple procedures, by conducting fractionation of pitch with an arom. hydrocarbon in two stages different from each other in the operating conditions. CONSTITUTION:Coal tar pitch 3 is mixed with an arom. hydrocarbon solvent 4 to prepare a mixture 5. The mixture is heated and fed into a first fractionation column 1, where the mixture is separated into a low specific gravity soln. phase and a high specific gravity soln. phase under conditions of a temp. ranging from the critical temp. of the solvent to 370 deg.C, a pressure ranging from the critical pressure of the solvent to 100kg/cm<2>G, and a solvent to pitch weight ratio of 0.5-4. The low specific gravity soln. 6 and a high specific gravity soln. 7 are separately taken out of the column. If necessary, a second solvent 8 is added to the low specific gravity soln. 6, followed by feeding into a second fractionation column 2, where phase separation is conducted under conditions of a temp. ranging from the critical temp. of the solvent to 370 deg.C, a pressure of 20-100kg/cm<2>G, and a solvent to pitch weight ratio of 0.5-10 and a condition satisfying at least one of the following requirements: higher temp., lower pressure, and higher solvent to pitch weight ratio than those used in the first fractionation column 1. The low specific gravity soln. 9 and high specific gravity soln. 10 are separately taken out of the column. The solvent is removed from the high specific gravity soln. from the first fractionation column 1, the high specific gravity solution 10 from the second fractionation column 2 and the low specific gravity soln.

Description

[Detailed Description of the Invention] Object of the Invention This invention separates coal tar pitch and extracts quinoline, which is made up of free carbon, ash, and other inorganic substances contained in the coal tar pitch. A raffinate phase mainly consists of components that are insoluble in benzene, that is, quinoline-soluble components (hereinafter referred to as QI main components), an extraction phase that mainly consists of components that are soluble in benzene (hereinafter referred to as BS components), and The present invention relates to a method for separating a liquid into an intermediate phase mainly consisting of components soluble in BI-95m (hereinafter referred to as BI-95m).

Conventional technology Coal tar pitch is a pitch used in the production of binders for briquette coal used in coke production, caking fillers for coal, raw materials for carbon fiber production, raw materials for needle coke production, electrodes for aluminum scouring, etc. Coke manufacturing raw material, r
It is used as a raw material for producing various carbon materials, such as a raw material for producing graphite materials for i-nuclear furnaces, and the demand for it is increasing year by year.

However, in coal tar pitch obtained from coal tar that is a by-product during coke production, there is a so-called QI main component that is not dissolved in quinoline and consists of free carbon, ash, and other inorganic substances, and this QI main component cannot be removed. For example, in the production of carbon fibers, various problems arise such as yarn breakage during melt spinning and deterioration of coking properties and graphitization properties, and as a result, it is not possible to produce high-quality carbon materials.

The method for removing the main QI component is to add a solvent to coal tar pitch, stir and mix to dissolve the solvent-soluble content in the coal tar pitch, and remove the solvent-insoluble content by static separation, centrifugation, filtration, etc. Separate by means.

A method of expelling the solvent from the obtained solvent solution of the solvent-soluble portion is disclosed in Japanese Patent Application Laid-Open No. 60-69195 and Japanese Patent Publication No. 59-10.
It is described in Japanese Patent Application Laid-open No. 716, Japanese Patent Application Laid-open No. 72983/1983, and the like.

Refined coal tar pitch from which the main QI component has been removed consists of a BS component (a component soluble in benzene) and a BI-QS component (a component insoluble in benzene and soluble in quinoline), of which the BI-QS component is highly concentrated. It is attracting attention as a raw material for value-added carbon products.

However, a method for separating this BI-QS component at high concentration has not yet been developed.

JP-A-56-18688 describes a method for separating asphaltenes from asphaltene-containing heavy hydrocarbon materials, and JP-A-57-78,489 describes a method for separating asphaltenes and resin from bituminous materials. Been l/X.

However, asqualtene contains BS along with the BI-QS component.
It also contains components, but does not describe how to separate them.

Japanese Patent Application Laid-open No. 80-51782 discloses beta resin (Bl
・This relates to a method for producing QI Respitch with an adjusted amount of QS components, which is obtained from aromatic solvents with boiling points below 180°C such as benzene and toluene, or mixed solvents thereof, light oil whose main components are benzene and toluene, or coke oven gas. The gas oil mainly consists of components with a boiling point of 250℃ or less,
After mixing coal tar or pitch, the mixture is maintained at a temperature of 150° C. or higher and a pressure of 5 atm or higher to separate light liquid and heavy liquid produced by gravity sedimentation. , β in beta resin
It only has the effect of reducing one component (quinoline-soluble, pyridine-insoluble component), and the BI@QS component content in the obtained QI-less pitch does not greatly exceed the BI@QS component content in the raw material. , it is not possible to obtain a high concentration of EI/QS components, for example, 50 wt% or more.

The present invention uses coal tar pitch, especially pitch with a softening point of 100°C or less obtained by distilling coal tar that is produced as a by-product during coal carbonization, as a raw material, and a raffinate phase mainly containing a QI acid component. B
The purpose is to obtain a high concentration of BI/QS components, which are raw materials for high value-added carbon products, by separating them into an extraction phase containing S components and an intermediate phase containing BI-QS components.

3. Means for Solving the Problems of the Invention The pitch separation method according to the invention introduces a mixture of coal tar pitch and an aromatic hydrocarbon-based first solvent into a first separation zone, and The temperature ranges from the critical temperature of 370℃ to the critical pressure of the solvent to 100Kg/cm2G, and the weight ratio of solvent/coal tar pitch ranges from 0.5 to 4 to separate low specific gravity liquid and high specific gravity liquid. phase separation into liquid and
A low specific gravity liquid and a high specific gravity liquid are extracted separately, and then the low specific gravity liquid is introduced into a second fractionation zone either as it is or with the addition of a second solvent, and the temperature is increased. The critical temperature of the solvent used is 370°C, the pressure is 20 to 10
0Kg/cm2G and the total solvent/coal tar pitch weight ratio introduced into the second separation zone is 0.5. ~lO and maintained under conditions that meet at least one of the following three requirements: higher temperature, lower pressure, and higher solvent/coal tar pitch weight ratio than in the first fractionation zone to form a low specific gravity liquid. The high specific gravity liquid is phase separated from the high specific gravity liquid, and the low specific gravity liquid and the high specific gravity liquid are separately extracted. It is characterized by removing the solvent from each.

That is, the present invention performs a two-stage fractionation operation using an aromatic hydrocarbon solvent under different operating conditions, and in particular, in the first stage, the fractionation operation is performed under supercritical conditions of the solvent used. be.

This will be explained in detail with reference to the process flow sheet shown in FIG.

A first fractionating column 1 is provided as a first fractionating zone, and a second fractionating column 2 is provided as a second fractionating zone, and the coal tar pitch from line 3 and the aromatic hydrocarbon solvent from line 4 are mixed into a mixer 5.
The mixture is heated and introduced into the first fractionation column 1, and the temperature is from the critical temperature of the solvent used to 370°C, the pressure is from the critical pressure of the solvent to 100 Kg/cm2G, and the weight ratio of solvent/coal tar pitch. (hereinafter referred to as solvent ratio) is 0.
5 to 4 to phase separate the low specific gravity liquid and the high specific gravity liquid, and the low specific gravity liquid is passed through line 6 from the top of the column.

A high specific gravity liquid is separately withdrawn from the bottom of the column via line 7.

Any coal tar pitch can be used as the raw material, and BI
- Pitch with a low content of QS components and a softening point of 100° C. or lower, preferably 70° C. or lower, obtained by distilling coal tar produced as a by-product during coal carbonization, can also be suitably used.

The aromatic hydrocarbon solvent is preferably C6 to C9 benzene or alkylbenzene, and more preferably one solvent selected from benzene, toluene and xylene, or a mixed solvent of two or more thereof.

The critical temperature of benzene is 289℃ and the critical pressure is 49Kg/
cm2G; Torrz 7 (7) Critical temperature is 319℃, critical pressure is 40Kg/cm2G; critical temperature of xylene is 3
The temperature was 43°C and the critical pressure was 36Kg/cm2G.

Although FIG. 1 shows the case where the coal tar pitch and the solvent are heated after being mixed, it is also possible to heat the coal tar pitch and the solvent separately and then mix them. , line mixer, stirring mixer, etc. can be used, but it is also possible to simply join the lines without installing the mixer 5.

In this first-stage fractionation operation, QIJ&min is extracted as a high specific gravity liquid, and the BS component and BI-QS component from which the QI acid component has been removed are extracted as a low specific gravity liquid. The solvent ratio in the first fractionation zone ranges from 0.5 to 4, preferably 0.5 to 4.
5-3. More preferably, it is in the range of 0.5 to 1.5.As shown in Table 1, which shows the results of testing the influence of condition changes in the first stage fractionation operation, it is better to reduce the solvent ratio. It is possible to increase the extraction rate of purified pitch (BSt molecule BI/QS components) that does not contain acid components.

The low specific gravity liquid extracted from the top of the column through line 6 is then introduced into second fractionation column 2. At this time, the low specific gravity liquid may be directly introduced into the second fractionation column, or the second solvent may be added through line 8 and introduced into the second fractionation column.

If you want to make the operating conditions of the first and second fractionation columns different by increasing the solvent ratio as described below, it is necessary to add a solvent here, but one or both of the temperature and pressure If the operating conditions of the first fractionation column and the second fractionation column are to be made different by changing the number of fractionators, there is no need to add a solvent here.

However, even in that case, adding a solvent is not a problem and is also effective.

The second solvent added before introducing the low specific gravity liquid extracted from the top of the first fractionation column through line 6 into the second fractionation column is:
Aromatic hydrocarbon solvents, light hydrocarbon solvents, alcohol solvents, ketone solvents, etc. may be used, but if the solvent is to be recovered and recycled, the same aromatic hydrocarbon solvent as the first solvent may be used. It is preferable that

The second solvent may be heated before being fed into line 6 from line 8 or after being fed into line 6.

In the second fractionation column 2, the temperature ranges from the critical temperature of the solvent to 370°C.
°C, the pressure is in the range of 20 to 100 Kg/cm2G, and the solvent ratio is in the range of 0.5 to 1O, and at least one of the three requirements of higher temperature, lower pressure, and higher solvent ratio than the first fractionation column 1 is satisfied. The low-density liquid is phase-separated into a low-density liquid and a high-density liquid by maintaining the conditions to satisfy the above conditions, and the low-density liquid is passed through line 9 from the top of the column.

The high-density liquid is separately withdrawn from the bottom of the column via line IO.

In this second-stage separation operation, components mainly composed of BS are extracted as a low-density liquid, and components with a high concentration of BI-QS are extracted as a high-density liquid.

Finally, by removing the solvent from each of the high specific gravity liquid extracted from the first fractionating column through line 7, the low specific gravity liquid extracted from the second fractionating column through line 9, and the high specific gravity liquid extracted through line 1O. (device not shown)
, QI acid component 1539 in coal tar pitch used as raw material
Minutes and BI@Qsr&minutes are separated and collected.

The pressure in the second fractionation column is 20 to 50Kg/cm"G
It is preferable that

It is economically preferable to recover and recycle the solvent removed from the separated components.

The influence of temperature, pressure, and solvent ratio on the extraction rate of purified pitch (BSr & 100% B molecule QS component) in the first stage fractionation treatment of the present invention was tested.

BS component 85% by weight as raw material coal tar pitch, B
A soft pitch (softening point: 40 DEG C.) containing 13% by weight of I-QS component and 2% by weight of QI component was used, and toluene was used as the aromatic hydrocarbon solvent.

As the first separation zone, the inner diameter is 30 mmφ and the length is 50 mm.
A 0 mm fractionation tower (empty tower) was used.

To explain according to Fig. 1, a soft pitch preheated to 120"0 is pumped through line 3 by a pitch supply pump, and toluene is pumped at room temperature from line 4 by a solvent supply pump at the solvent ratio shown in Table 1. 1. Both are mixed in a mixer (line mixer) 5, and this mixture of soft pitch and toluene is heated to the temperature shown in Table 1 with a heater. 1. Then, this mixture is introduced into the second fractionation column 2, and The conditions shown in the table are maintained to phase-separate the low-density liquid and the high-density liquid, and the high-density liquid, i.e., the raffinate phase mainly consisting of the QI component, is extracted from the bottom of the column via line 7, and the raffinate phase consisting mainly of QI components is drawn out from the top of the column via line 7. 6, the low specific gravity liquid was extracted.The low specific gravity liquid was flushed under normal pressure to remove the solvent and purified pitch (BS component + BI-
QS component) was collected. Table 1 shows the extraction ratio of purified pitch to raw pitch.

The purpose of the first-stage fractionation treatment is to remove the QI acid component (deashing), and the higher the extraction rate of purified pitch, the more desirable it is.

Table 1 The lower the solvent ratio, the higher the extraction rate can be expected, and the solvent weight ratio is 0.
7 to 1.5, a contracted pitch extraction rate of 96% by weight or more is achieved.

1 yen 1 yu (pressure 63-+48 kg/cm2G) BS component 85% by weight as raw material coal tar pitch, B
A soft pitch (softening point: 40°C) containing 13% by weight of I-QS component and 2% by weight of QI component was used, and toluene was used as the aromatic hydrocarbon solvent, and the above procedure was carried out according to the flow sheet shown in Figure 1. Soft pits were separated and processed.

The first fractionation tower has an inner diameter of 30 mmφ and a length of 500 mm.
An empty column with an inner diameter of 50 mmφ and a length of 500 mm as the second fractionation column.
A blank tower of mm was used.

The operating conditions of the first fractionation column were the same as in Test Example 15, at 120°C.
A soft pitch preheated to
Toluene is pumped at room temperature using a solvent supply pump from line 4 at a ratio of solvent ratio 1.0, and both are mixed in a mixer (line mixer) 5.
Heat this mixture of soft pitch and toluene to 340'0
and then introduce this mixture into the second fractionation column 2,
It is maintained under conditions of a temperature of 340°C and a pressure of 63 kg/cm2G to cause phase separation into a low specific gravity liquid and a high specific gravity liquid, and the high specific gravity liquid, that is, the raffinate phase mainly consisting of QI acid components, is extracted from the bottom of the column through line 7. A low specific gravity liquid was extracted from the top of the column through line 6.

Low specific gravity liquid extracted from the top of the first fractionation tower.

2nd fractionation column 2 as is (without further addition of solvent)
The high specific gravity liquid is introduced from the bottom of the column into a low specific gravity liquid and the high specific gravity liquid is maintained under conditions of a temperature of 340°C and a pressure of 48 kg/cm2G. The liquid was extracted.

The high specific gravity liquid extracted from the bottom of the first fractionating column and the high specific gravity liquid extracted from the bottom of the second fractionating column were each subjected to normal pressure flashing to remove the solvent.

Furthermore, the solvent was removed from the low specific gravity liquid extracted from the top of the second fractionation column using a continuous distillation column.

When the amount and composition of the product was measured, it was found that the high specific gravity liquid extracted from the bottom of the first fractionation column contained insoluble pitch containing 80% by weight of QITlt (2.5% by weight relative to the raw material);
The high density liquid extracted from the bottom of the second fractionation column contains BI,
QsrIi, split main body (content 80% by weight or more) pitch (
The low specific gravity liquid extracted from the top of the second fractionation column contained BS component-based pitch (94% by weight relative to the raw material).
．． 5% by weight) was recovered.

Example 2 (Pressure 63424 kg/cm2G) 1st
The step-by-step fractionation operation was the same as in Example 1, and the mixture was introduced into the second fractionation column as it was (without further addition of solvent), and the temperature was 34.
The fractionation operation was performed under the conditions of 0° C. and a pressure of 24 kg/cm 2G.

The solvent of Example 1 was extracted from each of the high specific gravity liquid extracted from the bottom of the first fractionating column, the high specific gravity liquid extracted from the bottom of the second fractionating column, and the low specific gravity liquid extracted from the top of the second fractionating column. The product was removed in a similar manner and the amount and composition of the product was measured. It was found that the high specific gravity liquid extracted from the bottom of the first fractionation column contained insoluble pitch containing 80% by weight of QI acid components (ratio to the raw material: 2.5%). The high density liquid extracted from the bottom of the second fractionation column contains mainly BI/QS components (content rate of 80% by weight or more), pitch (7.2% by weight relative to the raw material), and the column of the second fractionation column. Pitch consisting mainly of BS components (90.3% by weight relative to the raw material) was recovered from the low specific gravity liquid extracted from the top.

length m91 Yu (pressure 63 + 50 kg/Cm2G) (solvent ratio 1.0 → 2.0) The first stage fractionation operation was the same as in Example 1, and the low specific gravity liquid was extracted from the top of the first fractionation column through line 6. Before introducing it into the second fractionation column, toluene was added from line 8 to make the solvent ratio 2.0, and the temperature at the second stage was 340°C and the pressure was 50k.
The fractionation operation was performed under the following conditions: g/cm2Gc7).

The solvent of Example 1 was extracted from each of the high specific gravity liquid extracted from the bottom of the first fractionating column, the high specific gravity liquid extracted from the bottom of the second fractionating column, and the low specific gravity liquid extracted from the top of the second fractionating column. The product was removed in a similar manner and the amount and composition of the product was measured. It was found that the high specific gravity liquid extracted from the bottom of the first fractionation column contained insoluble pitch containing 80% by weight of QI acid components (ratio to the raw material: 2.5%). Weight%), from the high specific gravity liquid extracted from the bottom of the second fractionation column, BIΦQS components mainly (content rate of 80% by weight or more), pitch (8.3% by weight relative to the raw material), and from the top of the second fractionation column Pitch consisting mainly of BS components (89.2% by weight relative to the raw material) was recovered from the extracted low specific gravity liquid.

Example 4 (Changing only the pressure) Using the same coal tar pitch and toluene as used in Example 1, the temperature in the first fractionation column was 340°C and the pressure was 100°C.
kg/cm2G and a solvent ratio of 1.0 (7) to cause phase separation into a low specific gravity liquid and a high specific gravity liquid, and the low specific gravity liquid was directly introduced into the second fractionation column.

The results of measuring the recovery rate of the BI-QS component-based pitch extracted and recovered from the bottom of the second fractionation column and its BI/QS component content by changing only the pressure at a temperature of 340 ° C. As shown in the figure.

In Figure 2, the horizontal axis is the pressure (K
g/cm2G), the right vertical axis is the recovery rate (Rwt%) of pitch mainly composed of BI-QS components, and the left vertical axis is BI/QS
It represents the component content (0wt%), and the O mark and A line represent BI・
QSJili, the data on the recovery rate of the biogenic pitch, the Φ mark and the B line show the data on the BI-QS component content.

As is clear from the φ mark and BIa in Figure 2, when the pressure of the second fractionation column is 20 kg/cm2G or higher, the concentration of BI/QS components contained in the pitch obtained from the bottom of the second fractionation column is 75% by weight. Above, if the pressure is 24kg/cm2G or more, B
The concentration of I-QS component is 82% by weight or more, the pressure is 50kg/
Above cm2G, the concentration of BI-QSI & min is 90% by weight.
As mentioned above, even if the pressure is increased to 50 kg/cm2G or more, the concentration of BI/QS components does not increase much further.

On the other hand, as is clear from the O mark and the A line, the recovery rate of BI/QS component-based pitch increases rapidly at a pressure of 50 kg/cm2G or less, so the pressure in the second separation zone is preferably 20 to 50 kg/cm2G. 24 to 50Kg/
It is better to set it to cm2G.

Example 5 (Solvent ratio 0.7 → 2.0) A mixture consisting of the same coal tar pitch used in Example 1 and 21.0% by weight of benzene, 50.4% by weight of toluene, and 28.6% by weight of xylene. Using a solvent, the temperature in the first fractionation column is maintained at 350° C., the pressure is 50 kg/cm2G, and the solvent ratio is 0.7 to cause phase separation into a low specific gravity liquid and a high specific gravity liquid, and the low specific gravity liquid is subjected to second fractionation. Line 8 before introducing into the tower
Add the above mixed solvent to make the solvent ratio 2.0, and
The fractionation operation was carried out under the conditions of a temperature of 350°C and a pressure of 50 kg/am2G in the fractionation column.

The solvent of Example 1 was extracted from each of the high specific gravity liquid extracted from the bottom of the first fractionating column, the high specific gravity liquid extracted from the bottom of the second fractionating column, and the low specific gravity liquid extracted from the top of the second fractionating column. The product was removed in a similar manner and the amount and composition of the product was measured. It was found that the high specific gravity liquid extracted from the bottom of the first fractionation column contained insoluble pitch containing 6 oi of QI acid component (ratio to the raw material: 3.3 % by weight), the high specific gravity liquid extracted from the bottom of the second fractionation column contains mainly BI@QS components (content rate of 80% by weight or more), pitch (7.5% by weight relative to the raw material), and the column of the second fractionation column. Pitch consisting mainly of BS components (89.2% by weight relative to the raw material) was recovered from the low specific gravity liquid extracted from the top.

X''ull (temperature 330°C → 370°C) Using the same coal tar pitch used in Example 1, a mixed solvent consisting of 42.4% by weight of benzene and 57.6% by weight of toluene, the temperature in the first fractionation column was The conditions were maintained at 330°C, pressure 50kg/cm2G, and solvent ratio 1.0 to allow phase separation into a low specific gravity liquid and a high specific gravity liquid, and the low specific gravity liquid was directly introduced into the second fractionation column at a temperature of 370°C. pressure 50k
The fractionation operation was carried out under the condition of g/cm 2G.

The solvent of Example 1 was extracted from each of the high specific gravity liquid extracted from the bottom of the first fractionating column, the high specific gravity liquid extracted from the bottom of the second fractionating column, and the low specific gravity liquid extracted from the top of the second fractionating column. The product was removed in a similar manner and the amount and composition of the product was measured. The high density liquid extracted from the bottom of the first fractionation column was found to be an insoluble pitch containing 71.5% by weight of the Ql component (relative to the raw material). 2.8% by weight), and the high specific gravity liquid extracted from the bottom of the second fractionation column contains mainly BI/QS components (content rate of 80% by weight or more), pitch c to raw material ratio of 2-0% by weight), second fractionation Pitch consisting mainly of BS components (95.2% by weight relative to the raw material) was recovered from the low specific gravity liquid extracted from the top of the column.

Example 7 (pressure cuff 5450 kg/cm2G) (
Solvent ratio 1.0-1.5) (temperature 350°C → 370°C) The same coal tar pitch used in Example 1, 21.0% by weight of benzene, 50% by weight of toluene, and 28.6% by weight of xylene. Using a mixed solvent consisting of Before introducing the liquid into the second fractionation column, add the above mixed solvent from line 8 to make the solvent ratio 1.5,
Temperature in the second fractionation column: 370℃, pressure: 50kg/cm2G
The fractionation operation was carried out under the following conditions.

The solvent of Example 1 was extracted from each of the high specific gravity liquid extracted from the bottom of the first fractionating column, the high specific gravity liquid extracted from the bottom of the second fractionating column, and the low specific gravity liquid extracted from the top of the second fractionating column. The product was removed in a similar manner and the amount and composition of the product was measured. The high density liquid extracted from the bottom of the first fractionation column also contained insoluble pitch containing 80% by weight of the QI acid component (2° relative to the raw material). 5% by weight), the high specific gravity liquid extracted from the bottom of the second fractionation column contained mainly BI-QS components (content rate of 80% by weight or more), pitch C to raw material ratio of 6.0% by weight), The low specific gravity liquid extracted from the top of the tower contains pitch mainly consisting of BS components (
91.5% by weight of the raw material) was recovered.

C9 Effects of the invention l) With simple equipment and operation, BI/QS components, which are raw materials for high value-added carbon products, can be produced at high concentrations.

2) Yield and purity of BI/QS components can be freely controlled.

[Brief explanation of the drawing]

Fig. 1 is a process flow sheet for explaining an embodiment of the present invention, and Fig. 2 shows a process flow sheet for explaining an embodiment of the present invention, and Fig. 2 shows that when the pressure in the second separation zone is changed, a low specific gravity liquid is extracted from the second separation zone and recovered. FIG. 2 is a diagram showing the results of measuring the recovery rate and BI-QSJi content of pitch mainly composed of BI/QS components. 1: First fractionating column 2: Second fractionating column 3: Coal tar pitch supply line 4: First solvent supply line 5: Mixer 6: First fractionating column low specific gravity liquid withdrawal line 7: First fractionating column high specific gravity liquid Extraction line 8: Second solvent supply line

Claims (1)

[Claims] 1. A mixture of coal tar pitch and an aromatic hydrocarbon-based first solvent is introduced into a first separation zone, and the temperature is between the critical temperature of the solvent and 370°C, and the critical pressure of the solvent is 100 kg. /
The mixture is maintained under conditions of a pressure of cm^2G and a solvent/coal tar pitch weight ratio of 0.5 to 4 to cause phase separation into a low specific gravity liquid and a high specific gravity liquid, and the low specific gravity liquid and the high specific gravity liquid are separated. The low density liquid is then introduced into a second fractionation zone, either as is or with the addition of a second solvent, and the low density liquid is then introduced into a second fractionation zone at a temperature of
from the critical temperature of the solvent introduced into the fractionation zone to 370°C,
The pressure is in the range of 20 to 100 Kg/cm^2G and the weight ratio of total solvent/coal tar pitch introduced into the second fractionation zone is in the range of 0.5 to 10, and the temperature is higher and lower than that in the first fractionation zone. The liquid is maintained under conditions that satisfy at least one of the three requirements of pressure and high solvent/coal tar pitch weight ratio to cause phase separation into a low specific gravity liquid and a high specific gravity liquid, and the low specific gravity liquid and the high specific gravity liquid are separated. A pitch separation method characterized in that the solvent is removed from each of a high specific gravity liquid extracted from a first separation zone, a high specific gravity liquid and a low specific gravity liquid extracted from a second separation zone. 2. The pitch separation method according to claim 1, wherein the coal tar pitch is a pitch with a softening point of 100° C. or lower obtained by distilling coal tar that is produced as a by-product during coal carbonization. 3. The pitch separation method according to claim 1, wherein the aromatic hydrocarbon solvent is one solvent selected from benzene, toluene, and xylene, or a mixed solvent of two or more. 4. The pitch separation method according to claim 1, wherein the weight ratio of solvent/coal tar pitch in the first separation zone is in the range of 0.5 to 3. 5. The pitch separation method according to claim 4, wherein the weight ratio of solvent/coal tar pitch in the first separation zone is in the range of 0.5 to 1.5. 6. The pitch separation method according to claim 1, wherein the second solvent added before being introduced into the second separation zone is an aromatic hydrocarbon solvent. 7 If the pressure in the second separation zone is 20 to 50 kg/
The pitch separation method according to claim 1, wherein the pitch is cm^2G. 8. The pitch separation method according to claim 1, which comprises recovering and recycling the solvent removed from the separated liquid.