JP4436341B2 - Solvent extraction method, solvent extraction device, soil cleaning method, and soil cleaning device - Google Patents

Description

  The present invention relates to a technique for extracting components from a mixed solvent. In particular, the present invention relates to a technique for reusing a solvent used for soil cleaning.

  A technique for cleaning and detoxifying soil that may be contaminated with organic chemicals is desired. Such a technique is required to be able to remove many kinds of contaminants exemplified in oil and PCB and to be inexpensive.

  In Patent Document 1, in a method for washing soil contaminated with harmful substances such as oil, PCB, or dioxins, one or more main washing steps of immersing and washing the contaminated soil with a solvent, A rough cleaning process for immersing and washing soil with a solvent, and the contaminated soil is preliminarily cleaned by introducing the solvent contaminated in the main cleaning process into the rough cleaning process. A method is described. This document describes that a mixed solvent in which an appropriate amount of a solvent suitable for a contaminating component is mixed as a solvent may be used.

Patent Document 2 discloses that the efficiency related to the purification treatment of soil contaminated with harmful organic substances and the efficiency related to the purification treatment of water containing harmful organic substances is greatly improved. A method for purifying polluted water is described.
JP 2001-334249 A JP 2005-103417 A

An object of the present invention is to provide a soil cleaning method and a soil cleaning apparatus that can remove many kinds of contaminants contained in soil at low cost.
In order to remove many kinds of pollutants contained in the soil, it is desirable to wash with a plurality of kinds of solvents. In order to be inexpensive, it is desirable that the solvent used for washing is purified and used again for washing.

However, in the conventional distillation / purification method described in Patent Document 1, it has been difficult to sufficiently separate the hydrophilic solvent, the hydrophobic solvent, and water.
Accordingly, another object of the present invention is to provide a solvent extraction method and a solvent extraction apparatus which can be efficiently regenerated so that a plurality of types of solvents used for soil washing can be reused.

  In the following, means for solving the problem will be described using the numbers used in [Best Mode for Carrying Out the Invention] in parentheses. These numbers are added to clarify the correspondence between the description of [Claims] and [Best Mode for Carrying Out the Invention]. However, these numbers should not be used to interpret the technical scope of the invention described in [Claims].

  The solvent extraction method according to the present invention includes an extraction step of extracting a first solvent by distillation from a mixed solution containing water, a first solvent having a boiling point lower than that of water and a second solvent having a boiling point higher than that of water, and the concentration remaining in the extraction step. A separation step of separating the water and the second solvent contained in the liquid based on the specific gravity difference.

  In the solvent extraction method according to the present invention, the mixed solution further contains a mixed component dissolved in the second solvent and having a boiling point higher than that of the second solvent. The solvent extraction method includes a step of concentrating the mixed components by distilling the second solvent after the separation step.

  In the solvent extraction method according to the present invention, before the extraction step, an original mixed solution containing water, a first solvent having a lower boiling point than water, a second solvent having a higher boiling point than water, and a mixed component having a higher boiling point than the second solvent is obtained. Concentrating the mixed components by distillation and extracting volatile components. In the extraction step, volatile components are supplied as a mixed solution.

  In the solvent extraction method according to the present invention, the mixed solution further contains a mixed component dissolved in the second solvent and having a boiling point higher than that of the second solvent. The solvent extraction method includes a step of concentrating the mixed components by distilling the concentrate between the extraction step and the separation step.

  The soil washing method according to the present invention includes a step of washing soil using water, a washing solution containing a first solvent having a boiling point lower than water and a second solvent having a boiling point higher than water, and the washing solution used for washing in the washing step. A step of recovering a mixture, an extraction step of extracting the first solvent from the mixture by distillation, and a separation step of separating water and the second solvent contained in the concentrated liquid remaining in the extraction step based on the specific gravity difference Is provided.

  In the soil washing method according to the present invention, when a mixed component extracted from soil and dissolved in the second solvent and having a boiling point higher than that of the second solvent is contained in the mixed solution, the mixed component is obtained by distilling the second solvent after the separation step. The step of concentrating.

  In the soil washing method according to the present invention, when a mixed component extracted from soil and dissolved in the second solvent and having a boiling point higher than that of the second solvent is contained in the mixed solution, the mixed solution is distilled by distillation before the extraction step. Concentrating and removing components.

  In the soil washing method according to the present invention, when a mixed component extracted from soil and dissolved in the second solvent and having a boiling point higher than that of the second solvent is contained in the mixed solution, the concentrated solution is distilled between the extraction step and the separation step. Thereby concentrating the mixed components.

  In the soil washing method according to the present invention, the first solvent has hydrophilicity.

  In the soil washing method according to the present invention, the second solvent has hydrophobicity.

  A solvent extraction apparatus according to the present invention includes a distillation section (3, 43, 58) for extracting a first solvent by distillation from a mixed solution containing water, a first solvent having a boiling point lower than water and a second solvent having a boiling point higher than water. And a separation unit (12, 52, 76) for separating the concentrated component after the first solvent is extracted from the mixed solution based on the specific gravity difference between the water and the second solvent.

  In the solvent extraction apparatus according to the present invention, the mixed solution further contains a mixed component which is dissolved in the second solvent and has a boiling point higher than that of the second solvent. The solvent extraction apparatus includes a second distillation section (16) that concentrates the mixed components by distilling the second solvent separated by the separation section (12).

  The solvent extraction apparatus according to the present invention is a mixed component obtained by distilling an original mixed solution containing water, a first solvent having a lower boiling point than water, a second solvent having a higher boiling point than water, and a mixed component having a higher boiling point than the second solvent. And a mixed component concentrating section (28) for extracting volatile components and supplying them to the distillation section as a mixed solution.

  In the solvent extraction apparatus according to the present invention, the mixed solution further contains a mixed component which is dissolved in the second solvent and has a boiling point higher than that of the second solvent. The solvent extraction device concentrates the mixed component by distilling the mixed solution after the first solvent extraction after the first solvent is extracted from the mixed solution in the distillation unit (58), and extracts the volatile component to the separating unit. A mixed component concentrating section (68) for supplying the concentrate is provided.

  The soil cleaning apparatus according to the present invention cleans the soil using a cleaning liquid containing water, a first solvent having a boiling point lower than that of water and a second solvent having a boiling point higher than that of water, and collects a mixed liquid that is a cleaning liquid used for the cleaning. A cleaning unit (1) for performing the extraction, a distillation unit (3, 43, 58) for extracting the first solvent from the mixed solution by distillation, and water contained in the concentrated liquid remaining after the first solvent is extracted in the distillation unit. And a separation unit (12, 52, 76) for separating the second solvent based on the specific gravity difference.

  In the soil washing apparatus according to the present invention, the mixed solution contains a mixed component that is dissolved in the second solvent and has a boiling point higher than that of the second solvent. The soil washing apparatus includes a second distillation unit (16) that concentrates the mixed component by distilling the second solvent separated by the separation unit.

  The soil washing apparatus according to the present invention is a mixed component obtained by distilling an original mixed solution containing water, a first solvent having a boiling point lower than water, a second solvent having a higher boiling point than water, and a mixed component having a higher boiling point than the second solvent. And a mixed component concentrating section (28) for extracting volatile components and supplying them to the distillation section as a mixed solution.

  In the soil washing apparatus according to the present invention, the mixed solution further contains a mixed component dissolved in the second solvent and having a boiling point higher than that of the second solvent. The soil washing apparatus concentrates the mixed component by distilling the mixed solution after the first solvent extraction after the first solvent is extracted from the mixed solution in the distillation unit (58), and extracts the volatile component to the separating unit. A mixed component concentrating section (68) for supplying the concentrate is provided.

  In the soil cleaning apparatus according to the present invention, the first solvent has hydrophilicity.

  In the soil washing apparatus according to the present invention, the second solvent has hydrophobicity.

ADVANTAGE OF THE INVENTION According to this invention, the soil washing | cleaning method and soil washing | cleaning apparatus which can remove many types of contaminant contained in soil at low cost are provided.
Furthermore, according to the present invention, there are provided a solvent extraction method and a solvent extraction apparatus that efficiently regenerates a plurality of types of solvents used for soil washing.

(First embodiment)
The best mode for carrying out the present invention will be described below with reference to the drawings. The soil cleaning apparatus of the present invention is suitably used for cleaning soil containing PCB.

  FIG. 1 shows a soil washing apparatus in the present embodiment. The soil cleaning apparatus includes a soil cleaning unit 1. The soil cleaning unit 1 is supplied with soil to be cleaned and a mixed solvent for cleaning the soil. The soil cleaning unit 1 separates and discharges the cleaned soil and the mixed solvent used for cleaning (including contaminants and moisture extracted from the soil).

  The soil cleaning unit 1 is connected to a solvent recovery tank 2. The solvent recovery tank 2 stores the mixed solvent discharged from the soil washing unit 1. The solvent recovery tank 2 is connected to the distillation tower 3. The distillation tower 3 distills the mixed solvent supplied from the solvent recovery tank 2. The liquid phase mixed solvent accumulates at the bottom 4 of the tower. Volatile components are extracted from the top 6, cooled by the cooler 8, condensed, and stored in the hydrophilic solvent tank 10. The liquid stored in the hydrophilic solvent tank 10 is supplied to the soil washing unit 1 through a pipe (not shown).

  In the distillation tower 3, a plurality of temperature sensors T1 to T6 are installed at different heights. The distillation column 3 is further provided with a control unit (not shown). The control unit controls the opening degree of the inlet valve of the hydrophilic solvent tank 10 based on the temperature information detected by the temperature sensors T1 to T6. Techniques for controlling a general distillation column with such temperature sensors, control units and valves are known. Hereinafter, all of the distillation columns described in [Best Mode for Carrying Out the Invention] are provided with such a temperature sensor, a controller, and a valve, but the description thereof is omitted as appropriate.

  A decanter 12 is connected to the distillation column 3. The decanter 12 is supplied with the liquid accumulated at the bottom 4 of the distillation column 3. The decanter 12 separates the components of the supplied liquid based on the specific gravity difference by means such as centrifugation. The separated first component is stored in the separated water tank 14. The liquid stored in the separated water tank 14 is supplied to the soil washing unit 1 through a pipe (not shown). The separated second component is supplied to the subsequent distillation column 16.

  The distillation column 16 distills the supplied second component. The liquid collects at the tower bottom 18. Volatile components are extracted from the top 20, cooled by the cooler 22, and stored in the hydrophobic solvent tank 24. The liquid stored in the hydrophobic solvent tank 24 is supplied to the soil washing unit 1 through a pipe (not shown). A hydrophobic solvent tank 26 is connected to the distillation column 16. The liquid stored in the hydrophobic solvent tank 26 is connected to a processing apparatus for processing PCB through a pipe (not shown).

  Next, operation | movement of a soil washing apparatus provided with such a structure is demonstrated. The soil to be cleaned is input to the soil cleaning unit 1. A mixed solvent for washing the soil is introduced into the soil washing unit 1. The mixed solvent includes a hydrophilic solvent and a hydrophobic solvent. A mixed solvent having such components removes various pollutants that may be contained in the soil.

Examples of the hydrophilic solvent include the following substances. Values in parentheses indicate boiling points.
Methanol (64.5 ° C)
Ethanol (78.3 ° C)
Propyl alcohol (82.3 ℃)
Ethyl ether (34.5 ° C)
Acetone (56.5 ° C)
Methyl ethyl ketone (79.6 ° C)
Methyl acetate (57.5 ° C)
Ethyl acetate (77.2 ° C)
These substances have a lower boiling point than water.

Examples of the hydrophobic solvent include the following substances. The first value in parentheses indicates the boiling point, and the second value indicates the azeotropic point.
Heptane (98.4 ° C, 79.2 ° C)
Octane (125.7 ° C, 89.6 ° C)
Toluene (110.6 ℃, 84 ℃)
Xylene (139.1 ° C, 92 ° C)
Ethylbenzene (136.2 ° C, 92 ° C)
In the present embodiment, a hydrophobic solvent having a boiling point higher than that of water is preferably used.

  The mixed solvent used for soil cleaning in the soil cleaning unit 1 is stored in the solvent recovery tank 2. This mixed solvent includes water and PCB extracted from soil in addition to a hydrophilic solvent and a hydrophobic solvent.

  The mixed solvent stored in the solvent recovery tank 2 is supplied to the distillation tower 3. The mixed solvent is distilled inside the distillation column 3. The temperature of distillation is controlled to a temperature at which the hydrophilic solvent evaporates and accumulates at the top 6 and water accumulates at the bottom 4. The hydrophilic solvent is drawn from the top of the tower, cooled by the cooler 8, condensed, and stored in the hydrophilic solvent tank 10. The hydrophilic solvent stored in the hydrophilic solvent tank 10 is supplied to the soil washing unit 1 and used to wash the soil again.

  Control of the lower temperature of the distillation column 3 is performed as follows. If the detection temperature increases, the opening of the inlet valve of the hydrophilic solvent tank 10 is adjusted to stop the extraction of the top liquid (hydrophilic solvent), and the retained amount of the hydrophilic solvent having a low boiling point is increased. Lower the temperature at the bottom of the distillation column by pushing water having an intermediate boiling point downward. Conversely, if the temperature at the bottom of the distillation column decreases, the extraction of the top liquid (hydrophilic solvent) starts, the amount of hydrophilic solvent with a low boiling point is reduced, the water having an intermediate boiling point is raised, and the bottom of the distillation column is raised. Increase the temperature.

  As the hydrophilic solvent volatilizes from the mixed solvent, a liquid containing a hydrophobic solvent, water and PCB as components remains at the bottom of the tower. This liquid is centrifuged in a decanter 12. The water separated by the decanter 12 is stored in the separated water tank 14. The liquid mixture of the hydrophobic solvent and PCB separated by the decanter 12 is supplied to the distillation column 16 at the subsequent stage. By extracting water from the column bottom 4 of the distillation column 3, the distillation temperature on the column bottom side is lowered, the separation efficiency of the hydrophilic solvent on the column top side is increased, and the purity is improved. The mixing of the PCB into the water of the separation water tank 14 has an effect that the PCB is extracted to the hydrophobic solvent side, so that the saturation solubility of the PCB in the water becomes lower.

  The liquid mixture of the hydrophobic solvent and PCB is distilled in the distillation column 16. The temperature of the distillation column is controlled to a temperature at which the hydrophobic solvent accumulates at the top of the column and PCB does not accumulate. The hydrophobic solvent collected at the top of the column is drawn out, cooled by the cooler 22, condensed, and stored in the hydrophobic solvent tank 24. The stored hydrophobic solvent is supplied to the soil washing | cleaning part 1, and is used in order to wash | clean soil again. At the bottom of the column, a mixed liquid of PCB and hydrophobic solvent in which PCB is concentrated is left. This liquid is withdrawn from the distillation column 16 and stored in the hydrophobic solvent tank 26. The liquid stored in the hydrophobic solvent tank 26 is sent to a processing apparatus for processing PCB.

  According to such a soil cleaning apparatus, the soil is cleaned with a mixed solvent of water, a hydrophilic solvent and a hydrophobic solvent, so that many kinds of pollutants are efficiently removed. Since both the hydrophilic solvent and the hydrophobic solvent used for soil cleaning are separated from water and PCB and used again for soil cleaning, the cost of using the solvent and the cost of disposal are remarkably suppressed. Extraction of water, hydrophilic solvent and hydrophobic solvent is not performed by side-cutting from the middle of the distillation column, but by extraction from the top and bottom of the column and a decanter, so that the design and control of the distillation column is simple, and Separation with higher purity is possible. According to this apparatus, even when the hydrophobic solvent and water become an azeotropic substance, the hydrophobic solvent can be separated and reused.

  In ordinary distillation / fractionation, as in the present embodiment, distillation is not performed under the condition that a plurality of components to be finally separated remain in the tower bottom in a mixed state. However, the inventor has confirmed that water, hydrophilic solvent, hydrophobic solvent and PCB can be separated to a preferable degree by the distillation apparatus described above.

  FIG. 4 shows the temperature inside the distillation column 3 actually detected by the temperature sensors (thermocouples) T1 to T6. The reflux ratio is 2.2. FIG. 5 shows the same data in tabular form. FIG. 6 shows the feed liquid supplied to the distillation column 3 under the conditions shown in FIGS. 4 and 5, the hydrophilic solvent accumulated at the top 6 and the hydrophobic after being drawn out from the bottom and separated by the decanter 12. The composition of an organic solvent and water is shown.

(Second embodiment)
FIG. 2 shows a soil washing apparatus according to the second embodiment. The soil cleaning apparatus includes the same soil cleaning unit 1 and solvent recovery tank 2 as in the first embodiment. The solvent recovery tank 2 is connected to the distillation tower 28. The distillation tower 28 distills the mixed solvent supplied from the solvent recovery tank 2. The liquid phase mixed solvent accumulates in the tower bottom 30. Volatile components are extracted from the column top 32 and supplied to the distillation column 43 at the subsequent stage. A hydrophobic solvent tank 36 is connected to the distillation column 28. The liquid stored in the tower bottom 30 is supplied to the hydrophobic solvent tank 36. The liquid stored in the hydrophobic solvent tank 36 is supplied to a processing apparatus (not shown) for processing the PCB.

  The distillation column 43 is provided with temperature sensors T1 to T6, a control unit, and valves similar to those of the distillation column 3 in the first embodiment. A decanter 52 is connected to the distillation column. The decanter 52 is supplied with the liquid accumulated at the bottom 44 of the distillation column 43. The decanter 52 separates the supplied liquid component based on the difference in specific gravity by means such as centrifugation. The separated first component is stored in the separated water tank 54. The separated second component is stored in the hydrophobic solvent tank 56. The liquid stored in the hydrophobic solvent tank 56 is supplied to the soil washing unit 1 through a pipe (not shown). Volatile components in the distillation tower are extracted from the top 46, cooled by the cooler 48, condensed, and stored in the hydrophilic solvent tank 50. The liquid stored in the hydrophilic solvent tank 50 is supplied to the soil washing unit 1 through a pipe (not shown).

  Next, operation | movement of a soil washing apparatus provided with such a structure is demonstrated. In the soil washing part 1, soil is washed with a mixed solvent including a hydrophilic solvent and a hydrophobic solvent. The mixed solvent used for soil washing is stored in the solvent recovery tank 2. This mixed solvent includes water and PCB extracted from soil in addition to a hydrophilic solvent and a hydrophobic solvent.

  The mixed solvent stored in the solvent recovery tank 2 is supplied to the distillation tower 28. The mixed solvent is distilled inside the distillation column. The distillation temperature is such that PCB and a part of the hydrophobic solvent are accumulated in the tower bottom 30, and the mixed solvent is evaporated after the PCB removal including the hydrophilic solvent, water, and a part of the hydrophobic solvent, and is evaporated to the top of the tower. The temperature is controlled.

  The PCB and a part of the hydrophobic solvent accumulated in the tower bottom 30 are drawn out to the hydrophobic solvent tank 36 and further sent to a processing apparatus for processing the PCB through a pipe (not shown). From the column top 32, the mixed solvent is withdrawn after PCB removal, and is supplied to the distillation column 43 in the subsequent stage.

  In the distillation tower 43, the mixed solvent is distilled after the PCB removal. The temperature of distillation is controlled to a temperature at which the hydrophilic solvent accumulates at the top of the column and water and the hydrophobic solvent remain in the liquid phase at the bottom of the column. The hydrophilic solvent collected at the top 46 is extracted, cooled by the cooler 48, condensed, and stored in the hydrophilic solvent tank 50. The stored hydrophilic solvent is sent to the soil washing unit 1 through a pipe (not shown) and reused for washing the soil.

  The liquid at the bottom 44 is supplied to the decanter 12 and centrifuged. The water separated by the decanter 12 is stored in the separated water tank 14. The hydrophobic solvent separated by the decanter 12 is stored in the hydrophobic solvent tank 56. The stored hydrophobic solvent is supplied to the soil washing unit 1 and reused for washing the soil.

  According to such a soil washing apparatus, the effect shown in the first embodiment can be obtained. Further, since the PCB is separated by the distillation column 28 on the front stage side, the distillation column 43 on the rear stage side is not contaminated with the PCB, and the burden of device design and maintenance is reduced. Of the liquid at the bottom 44 of the distillation column 43 on the rear stage side, the hydrophobic solvent is drawn out and stored by overflow, and if the mixed liquid of water and hydrophobic solvent extracted by the side cut is sent to the decanter 52, the side cut is extracted. It is possible to reduce the amount of water, and to reduce the amount of reflux, thereby reducing the running cost.

(Third embodiment)
FIG. 3 shows a soil washing apparatus according to the third embodiment. The soil cleaning apparatus includes the same soil cleaning unit 1 and solvent recovery tank 2 as in the first embodiment. The solvent recovery tank 2 is connected to the distillation column 58. The distillation column 58 distills the mixed solvent supplied from the solvent recovery tank 2. The liquid phase mixed solvent is collected at the bottom 60 of the tower. Volatile components are extracted from the tower top 62, cooled by a cooler 64, and stored in a hydrophilic solvent tank 66. The hydrophilic solvent tank 66 is connected to the soil washing unit 1 through a pipe (not shown). The liquid collected at the bottom 60 is drawn out and supplied to the distillation column 68 at the subsequent stage.

  The liquid supplied to the subsequent distillation tower 68 is collected at the tower bottom 70. Volatile components accumulated in the column top 72 are extracted, cooled by the cooler 74, condensed, and supplied to the decanter 76. The decanter 76 separates liquid components based on the specific gravity difference by centrifugation or the like. The separated first component is stored in the water tank 78. A part of the separated second component is stored in the hydrophobic solvent tank 80, and the other part is returned to the top 72.

  Next, operation | movement of a soil washing apparatus provided with such a structure is demonstrated. In the soil washing part 1, soil is washed with a mixed solvent including a hydrophilic solvent and a hydrophobic solvent. The mixed solvent used for soil washing is stored in the solvent recovery tank 2. This mixed solvent includes water and PCB extracted from soil in addition to a hydrophilic solvent and a hydrophobic solvent.

  The mixed solvent stored in the solvent recovery tank 2 is supplied to the distillation column 58. The mixed solvent is distilled inside the distillation column. The temperature of distillation is controlled to a temperature at which PCB, water, and a hydrophobic solvent accumulate at the bottom of the column, and a hydrophilic solvent accumulates at the column top 62 as a volatile component. The hydrophilic solvent collected at the top 62 is drawn out, cooled by the cooler 64, condensed, and stored in the hydrophilic solvent tank 66. The stored hydrophilic solvent is supplied to the soil washing unit 1 and reused for washing the soil. A mixed liquid of a hydrophobic solvent, water, and PCB is accumulated in the tower bottom 60. This mixed solution is supplied to the distillation column 68 at the subsequent stage.

  The mixed solution supplied from the column bottom 60 is distilled in the distillation column 68. The temperature of the distillation is controlled to a temperature at which water and a part of the hydrophobic solvent accumulate in the column top 72 and a part of the hydrophobic solvent and PCB accumulate in the column bottom 70 in the liquid phase. The mixed liquid of the hydrophobic solvent and PCB collected at the bottom 70 is drawn out and stored in the hydrophobic solvent tank 82. The stored mixed liquid is sent to a processing apparatus for processing PCB.

  The water and the hydrophobic solvent collected at the top 72 are drawn out, cooled by the cooler 74, and sent to the decanter 76. The decanter 76 separates water and the hydrophobic solvent into two phases based on the specific gravity difference. The separated water is stored in the separated water tank 78. A part of the separated hydrophobic solvent is returned to the top 72. The remainder of the hydrophobic solvent is stored in the hydrophobic solvent tank 80. The stored hydrophobic solvent is sent to the soil washing unit 1 and reused for washing the soil.

  According to the soil washing apparatus having such a configuration, the hydrophilic solvent and the hydrophobic solvent used for washing the soil are treated and reused, as in the first embodiment. Components can be removed at low cost. Even when the hydrophobic solvent and water form an azeotropic mixture, separation and recovery are possible. In this soil washing apparatus, since the hydrophilic solvent is not supplied to the distillation column 68 on the rear stage, compared with the first and second embodiments, the equipment on the rear stage can be reduced in size.

FIG. 1 shows a soil washing apparatus according to a first embodiment. FIG. 2 shows a soil washing apparatus according to the second embodiment. FIG. 3 shows a soil washing apparatus according to the third embodiment. FIG. 4 is a graph showing the temperature inside the distillation column. FIG. 5 is a table showing the temperature inside the distillation column. FIG. 6 shows the composition of the solvent separated by the distillation column and decanter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Soil washing | cleaning part 2 ... Solvent recovery tank 3 ... Distillation tower 4 ... Tower bottom 6 ... Tower top 8 ... Cooler 10 ... Hydrophilic solvent tank 12 ... Decanter 14 ... Separation water tank 16 ... Distillation tower 18 ... Tower bottom 20 ... Tower top 22 ... Cooler 24 ... Hydrophobic solvent tank 26 ... Hydrophobic solvent tank 27 ... Soil washing section 28 ... Solvent recovery tank 29 ... Distillation tower 30 ... Tower bottom 32 ... Tower top 34 ... Cooler 36 ... Hydrophobic solvent tank 42 ... distillation tower 44 ... tower bottom 46 ... tower top 48 ... cooler 50 ... hydrophilic solvent tank 52 ... decanter 54 ... separation water tank 56 ... hydrophobic solvent tank 57 ... soil washing part 58 ... solvent recovery tank 59 ... distillation tower 60 ... bottom 62 ... tower top 64 ... cooler 66 ... hydrophilic solvent 68 ... distillation tower 70 ... tower bottom 72 ... tower top 74 ... cooler 76 ... decanter 78 ... separation water tank 80 ... hydrophobic solvent tank 82 ... hydrophobic Solvent tank

Claims (12)

A method for extracting components of a solvent used for soil washing,
An extraction step of extracting the first solvent by distillation from a mixed solution containing water, a first solvent having a boiling point lower than water and a second solvent having a boiling point higher than water;
A separation step of separating water contained in the concentrated liquid remaining in the extraction step and the second solvent based on a specific gravity difference;
Prior to the extraction step, the mixing is performed by distilling the raw mixture containing water, a first solvent having a boiling point lower than water, a second solvent having a boiling point higher than water, and a mixed component having a boiling point higher than that of the second solvent. And concentrating the components and extracting the volatile components,
In the extraction step, the volatile component is supplied as the mixed solution. The solvent extraction method according to claim 1,
PCB contained in the soil is separated in the step of extracting the volatile component, and is removed from the volatile component. Washing the soil with a cleaning solution comprising water, a first solvent having a boiling point lower than water and a second solvent having a boiling point higher than water;
Recovering the mixed liquid that is the cleaning liquid used for cleaning in the cleaning step;
An extraction step of extracting the first solvent from the mixture by distillation;
A separation step of separating water contained in the concentrated liquid remaining in the extraction step and the second solvent based on a specific gravity difference;
Prior to the extraction step, comprising distilling the mixed solution to concentrate and remove a mixed component extracted from the soil and dissolved in the second solvent and having a boiling point higher than that of the second solvent. Cleaning method. A soil washing method according to claim 3,
PCB contained in the soil is removed in the step of concentrating and removing the mixed components. The soil washing method according to claim 3 or 4,
The first solvent has a hydrophilic property. A soil washing method according to any one of claims 3 to 5,
The soil washing method, wherein the second solvent has hydrophobicity. An apparatus for extracting the components of the solvent used for soil cleaning,
A distillation unit for extracting the first solvent by distillation from a mixed solution containing water, a first solvent having a boiling point lower than water and a second solvent having a boiling point higher than water;
A separation unit that separates a concentrated component after the first solvent is extracted from the mixed solution based on a specific gravity difference between water and the second solvent;
Concentrating the mixed components by distilling water, a first solvent having a lower boiling point than water, a second solvent having a higher boiling point than water, and a mixed component having a higher boiling point than the second solvent, and volatile components A solvent extraction device comprising: a mixed component concentration unit that extracts and supplies the mixture to the distillation unit as the mixed solution. The solvent extraction device according to claim 7,
PCB contained in the soil is separated in the mixed component concentration unit and removed from the volatile components. The soil is washed with water, a cleaning solution containing a first solvent having a boiling point lower than water and a second solvent having a boiling point higher than water, and dissolved in the second solvent contained in the cleaning solution and the soil used for the cleaning. A cleaning unit for recovering a raw liquid mixture containing a mixed component having a boiling point higher than that of the second solvent ;
A mixed component concentrating unit that concentrates the mixed component by distilling the original mixed solution, extracts a volatile component, and supplies the volatile component as a mixed solution;
A distillation section for extracting the first solvent from the mixture by distillation;
A soil washing apparatus comprising: a separation unit that separates water contained in the concentrated liquid remaining after the first solvent is extracted in the distillation unit and the second solvent based on a difference in specific gravity. A soil cleaning apparatus according to claim 9,
The PCB contained in the soil is separated in the mixed component concentration unit and removed from the volatile components. A soil cleaning apparatus according to claim 9 or 10,
The first solvent has a hydrophilic property. A soil cleaning apparatus according to any one of claims 9 to 11,
The second solvent has a hydrophobic soil cleaning device.

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