JP2007330964A - High-efficiency separation method and apparatus for solid/liquid mixture by supercritical carbon dioxide and/or liquid carbon dioxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-efficiency separation method for a solid/liquid mixture by supercritical carbon dioxide and/or liquid carbon dioxide, and to provide its apparatus. <P>SOLUTION: Provided are the method for separating the solid/liquid mixture including the step of separating the solid/liquid mixture by utilizing difference in the specific gravity by using supercritical carbon dioxide and/or liquid carbon dioxide as a solvent for separation by difference in the specific gravity; the method for separating the solid/liquid mixture including the step of separating the solid/liquid mixture by utilizing separation by difference in the specific gravity and extraction separation by combining the step of separation by difference in the specific gravity and the step of extraction separation using supercritical carbon dioxide and/or liquid carbon dioxide as a solvent for extraction separation; the method for separating the solid/liquid mixture including steps of mixing the solid/liquid mixture with supercritical carbon dioxide and/or liquid carbon dioxide and controlling the density and viscosity of a fluid after mixing the solid/liquid mixture with supercritical carbon dioxide and/or liquid carbon dioxide; and its apparatus. This can provide new, high-efficiency separation method and apparatus for the solid/liquid mixture using supercritical carbon dioxide as the solvent for separation by the difference in the specific gravity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high-efficiency separation method and apparatus for a solid-liquid mixed material using supercritical carbon dioxide and / or liquid carbon dioxide, and more specifically, a slurry using supercritical carbon dioxide and / or liquid carbon dioxide. Using supercritical carbon dioxide and / or liquid carbon dioxide as a separation solvent that enables separation and recovery of solid-liquid mixed substances such as waste liquid by specific gravity difference separation or by specific gravity difference separation and extraction separation with high separation efficiency The present invention relates to a new separation method and apparatus for a solid-liquid mixed material used.

  Assuming that the solid-liquid mixture is, for example, waste silicon slurry discharged in the semiconductor and solar cell industries, this waste slurry is mixed with coolant (mineral oil, polyethylene glycol, water, etc.) and abrasive when slicing the silicon ingot. It is generated by using a slurry (abrasive) in which grains (SiC, diamond, alumina, etc.) are mixed. The slurry used for the slicing process contains a lot of silicon scrap generated during the cutting process and degrades the processing accuracy, and is eventually discarded. Since this waste slurry contains usable coolant and abrasive grains, it is desired to separate and recover them from the waste slurry. Conventionally, various ideas have been proposed (Patent Documents 1 to 6), None of them are in practical use. In recent years, the demand for semiconductors and solar cells has been greatly increased, and silicon itself is becoming tight, and efficient separation is required from the viewpoint of silicon recovery.

  Prior literature discloses a method of diluting an oil-based slurry waste liquid with an extractant such as kerosene and recovering abrasive grains (SiC) that precipitate due to a difference in specific gravity (Patent Document 7). In other prior literatures, SiC particles are separated by mixing fine particles with a collecting agent such as sodium alkyl sulfonate and a foaming agent in a slurry waste liquid separated by a filter press or the like. (Patent Document 8).

  In these methods, it is necessary to add a new dispersant, and new waste is generated by separating useful components of the slurry waste solution. For this reason, an extraction separation method using supercritical carbon dioxide that does not require post-treatment of a solvent has attracted attention. In the prior literature, after extracting and separating organic matter using subcritical or supercritical carbon dioxide, the temperature and pressure are lowered to separate carbon dioxide and organic matter, and further, carbon dioxide is recovered and again subcritical or A method of using supercritical carbon dioxide as an extractant is disclosed (Patent Document 9). A number of other organic substance dissolution extraction techniques have been proposed for using such supercritical carbon dioxide, but this type of method is limited to substances whose target extraction substance is soluble in supercritical carbon dioxide. There was a problem that.

Japanese Patent No. 3199159 JP 11-48146 A JP 2002-28866 A JP 2003-225700 A JP 2000-254543 A JP-A-11-172237 JP-A-9-109144 JP 2004-223321 A Japanese Patent Laid-Open No. 8-183989

  Under such circumstances, the present inventors have aimed to develop a high-efficiency separation technique for a new solid-liquid mixed material using supercritical carbon dioxide and / or liquid carbon dioxide in view of the above-described conventional technology. As a result of intensive research, the separation of a new solid-liquid mixed material using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent and adjusting the density and viscosity of the fluid with the solvent is performed. The technology has been successfully established, and the present invention has been completed.

  That is, the present invention provides a new method for separating a solid-liquid mixed substance that can separate a solid-liquid mixed substance such as slurry waste liquid with high separation efficiency using supercritical carbon dioxide and / or liquid carbon dioxide, and the method thereof. The object is to provide an apparatus. In addition, the present invention combines the specific gravity difference separation using supercritical carbon dioxide and / or liquid carbon dioxide and the extraction separation, and also controls the density and viscosity of the fluid with the solvent, so that the solid-liquid can be obtained with high separation efficiency. It is an object of the present invention to provide a new solid-liquid mixed material separation method and apparatus capable of separating and recovering mixed materials.

The present invention for solving the above-described problems comprises the following technical means.
(1) A method for separating a solid-liquid mixed material, wherein supercritical carbon dioxide and / or liquid carbon dioxide is used as a specific gravity difference separation solvent, and the solid-liquid mixed material is separated using the specific gravity difference.
(2) The solid-liquid mixed material separation method according to (1), wherein the solid-liquid mixed material is a slurry waste liquid.
(3) The method for separating a solid-liquid mixed material according to (2), wherein the slurry waste liquid is a slurry waste liquid generated in a silicon wafer manufacturing process.
(4) The density of the specific gravity difference separation solvent is adjusted by changing the temperature and / or pressure conditions to control the separation efficiency by the specific gravity difference separation, and / or the specific gravity difference separation is adjusted by adjusting the flow rate of the specific gravity difference separation solvent. The method for separating a solid-liquid mixed material according to the above (1), wherein the separation efficiency is controlled.
(5) The specific gravity difference separation step described in (1) above and the extraction separation step using supercritical carbon dioxide and / or liquid carbon dioxide as an extraction separation solvent are combined to separate and extract a solid-liquid mixed material by specific gravity difference. A method for separating a solid-liquid mixed material, wherein separation is performed using separation.
(6) The solid-liquid mixed substance separation method according to (5), wherein the specific gravity difference separation and the extraction separation are performed simultaneously in the same system.
(7) The density of the specific gravity difference separation solvent and / or the extraction separation solvent is adjusted by changing the temperature and / or pressure conditions to control the separation efficiency by the specific gravity difference separation and / or the extraction separation, and / or the specific gravity difference. The method for separating a solid-liquid mixed material according to (5) above, wherein the separation efficiency by specific gravity difference separation and / or extraction separation is controlled by adjusting the flow rate of the separation solvent and / or the extraction separation solvent.
(8) The solid-liquid mixed material separation method according to (5), wherein the specific gravity difference separation and the extraction separation are continuously performed in the same system.
(9) The method for separating a solid-liquid mixed material according to (5), including a recycling process for recovering a reusable material separated by using specific gravity difference separation and extraction separation.
(10) A separation apparatus that separates a solid-liquid mixed material using specific gravity difference separation using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent. Solid-liquid mixing comprising means for introducing critical carbon dioxide and / or liquid carbon dioxide and means for introducing a solid-liquid mixed substance, and means for adjusting the temperature in the system of the separator Substance separation device.
(11) Liquid carbon dioxide pressurizing means for sending liquid carbon dioxide or supercritical carbon dioxide to the lower part of the separator; for supercritical carbon dioxide, heating means; solid-liquid mixing in the intermediate part of the separator Pressurizing means for sending the substance, means for storing the solid substance separated by the specific gravity difference in the lowermost part of the separator, means for filtering the separated solvent and liquid substance flowing out from the uppermost part of the specific gravity difference separator, and the pressure in the system The solid-liquid mixed substance separation device according to (10), further comprising a means for adjusting and a gas-liquid separation means for separating the separation solvent and the liquid substance.
(12) A separation apparatus that separates a solid-liquid mixed material using a specific gravity difference and extraction separation using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent and an extraction separation solvent. The separation unit and the extraction / separation unit are included in the same vertical system, the extraction / separation unit is installed in the lower part, and the specific gravity difference separation unit is installed in the upper part. Supercritical carbon dioxide and / or liquid Means for introducing carbon and means for introducing the solid-liquid mixed substance at a predetermined position of the specific gravity difference separation section, and means for adjusting the temperature in the system of the separator. Separation device for liquid mixed substances.
(13) Liquid carbon dioxide pressurizing means for sending liquid carbon dioxide or supercritical carbon dioxide to the lower part of the extraction / separation section, and in the case of supercritical carbon dioxide, heating means, intermediate part of the specific gravity difference separation section Means for sending the solid-liquid mixed material to the unit, means for storing the solid substance separated in the specific gravity difference separation unit and extraction separation unit at the bottom of the separator, and the separation solvent and liquid substance flowing out from the top of the specific gravity difference separation unit The solid-liquid mixed substance separation device according to (12), comprising filtration means, means for adjusting the pressure in the system, and gas-liquid separation means for separating the separation solvent and the liquid substance.
(14) The solid-liquid mixed substance separation device according to (10) and (12), comprising means for individually controlling the temperature in the separator in a plurality of vertical portions.
(15) The solid-liquid mixed substance separation device according to (10) and (12), wherein the gas-liquid separation device includes an evaporation unit for a separation solvent (liquid carbon dioxide).
(16) The solid-liquid mixed substance separation device according to (15), which has a solvent circulation mechanism in which a gas separation solvent (carbon dioxide gas) is cooled and condensed to form liquid carbon dioxide and recycled.
(17) The solid-liquid mixed substance separation device according to (11) and (13), which has means for continuously discharging the solid substance collected and stored in the lower part of the separator.
(18) The solid-liquid mixed substance separation device according to (17), wherein the solid substance continuous discharge means is a water slurry discharge means by high-pressure water injection.
(19) The solid-liquid mixed substance separation device according to (18), wherein the water slurry discharging means by high-pressure water injection includes high-pressure solid-liquid separation means.
(20) The solid-liquid mixed substance separation device according to (19), wherein the high-pressure solid-liquid separation means is a high-pressure filter or a high-pressure cyclone.
(21) The solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are mixed, and the density and viscosity of the fluid after mixing the solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are controlled. The solid-liquid separation method according to (1).
(22) The solid-liquid mixed substance and supercritical carbon dioxide and / or liquid carbon dioxide are mixed in advance to control the density and viscosity of the fluid, and then solid-liquid separation is performed using a difference in specific gravity. Solid-liquid separation method.
(23) The solid-liquid separation method according to (22), wherein the supercritical carbon dioxide and / or liquid carbon dioxide to be mixed with the solid-liquid mixed material is obtained by circulating and reusing the fluid after solid separation.
(24) The apparatus used in the solid-liquid separation method according to (21), wherein the solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are mixed, and the density and viscosity of the fluid after mixing. A mixing control apparatus comprising density and viscosity adjusting means for controlling the viscosity.
(25) An apparatus used in the solid-liquid separation method according to (21), wherein the solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are mixed in advance, and the mixture is mixed with the density of the fluid and A mixture supply control device comprising a mixture supply means for supplying a specific gravity difference separation region while controlling viscosity.
(26) An apparatus for use in the solid-liquid separation method according to (21), further comprising a fluid circulation means for circulating and reusing the fluid after solid-liquid separation.

Next, the present invention will be described in more detail.
The present invention is a method for separating a solid-liquid mixed material such as slurry waste liquid with high separation efficiency, and using the supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent, Solid-liquid separation is performed using the difference. In addition, the present invention combines the specific gravity difference separation and the extraction separation using supercritical carbon dioxide and / or liquid carbon dioxide as an extraction separation solvent, and uses the specific gravity difference separation and extraction separation for the solid-liquid mixed material. And are separated.

  In the present invention, in the solid-liquid mixed substance separation process by the specific gravity difference separation, the density of the specific gravity difference separation solvent is adjusted by changing temperature and / or pressure conditions, and / or the flow rate of the specific gravity difference separation solvent is adjusted. Thus, it is possible to control the separation efficiency by specific gravity difference separation. Similarly, in the solid-liquid mixed substance separation process by specific gravity difference separation and extraction separation, similarly, the density of the solvent is adjusted by changing the temperature and / or pressure conditions, and / or the flow rate of the solvent is adjusted. Thus, it is possible to control the separation efficiency by specific gravity difference separation and / or extraction separation.

  In the present invention, supercritical carbon dioxide and / or liquid carbon dioxide is efficiently contact-mixed with a solid-liquid mixed substance, for example, supercritical carbon dioxide and / or oil components contained in the solid-liquid mixed substance. Alternatively, liquid carbon dioxide dissolves, and the density and viscosity of the mixed fluid decrease. As a result, the critical flow velocity of solids increases, and solid-liquid separation is efficiently performed due to the difference in specific gravity.

  In the present invention, in the separation process of the solid-liquid mixed material by the specific gravity difference separation, the density and viscosity of the mixed fluid may be adjusted by changing the temperature and / or pressure to control the separation efficiency by the specific gravity difference separation. Is possible. Also, when the density and / or particle size of solids in the solid-liquid mixed material is different, the solids can be separated from each other by controlling the rising speed of the mixed fluid in the separator relative to the limit flow rate of the solids. It is.

  Here, the case where the solid-liquid mixed material is, for example, an oil-based slurry waste liquid will be described. The slurry waste liquid is jetted and supplied from the spray nozzle to the specific gravity difference separator, and comes into contact with supercritical carbon dioxide and / or liquid carbon dioxide. Further, stirring is performed in a specific gravity difference separator. As a result, supercritical carbon dioxide and / or liquid carbon dioxide are efficiently contact-dissolved in the oil-based components in the slurry waste liquid, and the density and viscosity of the mixed fluid after dissolution are reduced, so that the solids contained in the slurry waste liquid It is possible to construct a solid-liquid mixed substance separation process and separation apparatus that can separate the components by specific gravity difference.

  In addition, the solid-liquid mixed substance and supercritical carbon dioxide and / or liquid carbon dioxide are mixed in advance in a mixer / or high-pressure pipe, and after mixing, the mixed fluid is supplied to the specific gravity difference separation region, thereby the specific gravity difference. It is also possible to achieve separation. Further, the above-described specific gravity difference separation can be achieved even by using a method in which the supercritical carbon dioxide and / or liquid carbon dioxide mixed with the solid-liquid mixed material circulates and reuses the fluid after the solid separation.

  In the present invention, in addition to liquid carbon dioxide, supercritical carbon dioxide having a temperature of 31.17 ° C. or higher and a pressure of 7.386 MPa or higher is used. The density of this supercritical fluid is close to that of a liquid, and its diffusion coefficient is significantly higher than that of a liquid. It has the action of dissolving nonpolar and weakly polar oils and fats, and its dissolving power changes by changing temperature and / or pressure. . Carbon dioxide can be vaporized, removed, liquefied and reused only under pressure conditions, and these circulation processes can be easily constructed.

  In the present invention, preferable examples of the solid-liquid mixed material include slurry waste liquids such as a general polishing / cutting agent slurry waste liquid and a silicon slurry waste liquid generated in a silicon wafer manufacturing process. These slurry waste liquids contain abrasives, abrasive grains used as abrasives, coolants, and the like. Examples of the abrasive grains include fine alumina, colloidal silica, silicon carbide, cerium oxide, silicon oxide, boron carbide, boron nitride, zirconium oxide, fine diamond, and fine sapphire. Examples of the coolant include oil-based coolants such as mineral oil, water-based coolants such as poly water-soluble glycols and amines, and lubricants. The coolant may contain a surfactant, water, a solvent, and the like.

  Generally, in abrasives and abrasives, the abrasive grains are usually dispersed in a coolant and a lubricant. These slurry waste liquids contain solids such as the above-mentioned abrasive grains, chips such as silicon, polishing scraps, iron scraps derived from wire saws, and fragments of crushed abrasive grains. As a composition of slurry waste liquid, for example, in the case of slurry waste liquid generated in a silicon wafer manufacturing process, generally, SiC abrasive grains are 48 to 55 w%, coolant is 30 to 35 wt%, Si scrap is 9 to 10%, and others As a percentage of iron scrap. The present invention is not limited to the above-described slurry waste liquid, and can be applied as a means for separating all kinds of solid-liquid mixed substances having properties and compositions equivalent or similar to those.

  When supercritical carbon dioxide and / or liquid carbon dioxide is used as a specific gravity difference separation solvent and a solid-liquid mixed material is separated using a specific gravity difference, the solid-liquid mixed material is separated from the supercritical carbon dioxide and / or liquid dioxide. A specific gravity difference separator into which carbon is fed is introduced from an intermediate portion, and solid-liquid separation is performed using the specific gravity difference. For example, an oil component is separated into an upper layer portion and a solid substance is separated into a lower layer portion. For example, in the case of a silicon slurry waste liquid using mineral oil as a coolant, the coolant is separated in the upper layer portion and the solid is precipitated in the lower layer portion. After discharging this precipitated solid matter to the outside, an aqueous solution containing a surfactant is added to the collected solid matter, mixed, and allowed to stand, so that silicon chips and iron scraps are also obtained as a supernatant, as a precipitate. , SiC separates. If necessary, iron scraps can be efficiently recovered by irradiating ultrasonic waves during mixing or by putting a magnet in the supernatant. By repeating the above operation, SiC is refined and can be reused as abrasive grains.

In the present invention, in the specific gravity difference separation, the density is changed by changing the temperature and / or pressure of the supercritical carbon dioxide and / or liquid carbon dioxide, which is the specific gravity difference separation solvent, and / or the flow rate of the separation solvent is increased. By adjusting, the separation efficiency can be increased. For example, in order to separate the liquid component (low density ρ _L ) and the solid component (high density ρ _H ) constituting the solid-liquid mixed substance, the density ρ _CO2 of the specific gravity difference separation solvent is ρ _L <ρ _CO2 <ρ. It is necessary to be in the relationship of _H , and high separation efficiency can be achieved by adjusting the density of the specific gravity difference separation solvent. In the case of silicon slurry waste liquid, the density of the coolant, which is a liquid component, is about 800 kg / m ³ , and the density of SiC, which is a solid main component, is about 3000 kg / m ³ , so the density of the specific gravity difference separation solvent is 800 kg / m ³ or more. It is required to be 3000 kg / m ³ or less.

If the density of the separation solvent is 800 kg / m ³ or more, the coolant can be separated into the upper part, and if it is 3000 kg / m ³ or less, SiC can be separated into the lower part. However, since the density of carbon dioxide does not exceed 3000 kg / m ³ , it may be substantially 800 kg / m ³ or more (about 1500 kg / m ³ even in solid carbon dioxide dry ice). For saturated liquid carbon dioxide, this condition is a saturation temperature of 17 ° C. (saturation pressure at that time 5.3 MPa) or less, and for pressurized liquid carbon dioxide or supercritical carbon dioxide, 20 MPa, 47 ° C. or less, 30 MPa. This is achieved at 67 ° C. or lower.

On the other hand, the sedimentation property of the solid particles is evaluated by a critical flow rate calculated from the Stokes equation, and the flow rate is determined so that the rising speed of the separation solvent is smaller than this value. In other words, it means that the cross-sectional area (inner diameter) of the separator is determined so that the rising speed of the separation solvent is sufficiently smaller than the critical flow rate for a constant flow rate. Assuming that the particle size of SiC is 10 μm and supercritical carbon dioxide (density 840 kg / m ³ ) at 40 ° C. and 20 MPa is used as a separation solvent, the critical flow rate is calculated as 5.4 m / h. It is preferable that the flow rate is adjusted so that the rising speed of carbon dioxide is a value sufficiently smaller than this.

In the case of an aqueous slurry, since the liquid component is water and the density is 1000 kg / m ³ , a larger numerical value is required for the density of the specific gravity difference separation solvent. For saturated liquid carbon dioxide, this condition is a saturation temperature of −14 ° C. (saturation pressure at that time 2.4 MPa) or less, and for pressurized liquid carbon dioxide, it is 5 ° C. or less at 20 MPa and 15 at 30 MPa. If it is supercritical carbon dioxide below ℃, it is achieved at 36 ℃ or below at 50 MPa. According to this operation, dehydration and drying can be performed at a low temperature. In any case, when the separation operation is completed, a reusable substance out of the solvent, liquid component, and solid substance can be recovered and reused.

  Next, in the present invention, the specific gravity difference separation is combined with the extraction separation using supercritical carbon dioxide and / or liquid carbon dioxide as the extraction separation solvent, and the solid-liquid mixed substance is utilized by the specific gravity difference separation and the extraction separation. Can be separated. In this case, the above-mentioned extraction / separation basically involves solid-liquid separation by bringing the solid-liquid mixed material into contact with supercritical carbon dioxide and / or liquid carbon dioxide and, for example, dissolving and extracting oil components in the extraction / separation solvent. Is done. Also in this extraction / separation step, it is possible to improve the separation efficiency by adjusting the temperature and / or pressure of the extraction / separation solvent and / or adjusting the flow rate of the extraction / separation solvent.

  For example, in the case of oil-based coolant, high extraction efficiency can be obtained due to the solvent effect of supercritical carbon dioxide under high pressure conditions. Since supercritical carbon dioxide has high diffusibility and permeability and low viscosity, it is easy for a solid substance to enter the microstructure, and high extraction efficiency can be expected. In general, in the case of slurry waste liquid, 98% wt% or more of the dissolved components are recovered, and since it is a dry process, the extracted coolant is not denatured and has no residual carbon dioxide or impurities. The coolant can be recovered.

  In the present invention, the specific gravity difference separation and the extraction separation can be performed in the same system. For example, the upper stage of the separation apparatus is configured as a specific gravity difference separator and the lower stage is configured as an extraction separator so that the specific gravity difference separation is performed in the first step and the extraction separation is performed in the second step. Is preferred. In addition, a reusable substance can be recovered from the solid substance obtained by solid-liquid separation by the above process. For example, in the case of silicon slurry waste liquid, the precipitated solid matter is discharged to the outside, and then an aqueous solution containing a surfactant is added to the collected solid matter, mixed, and allowed to stand to obtain silicon chips and iron as a supernatant. Since SiC is separated as waste and as precipitate, reusable SiC can be efficiently recovered.

  As described above, by integrating the specific gravity difference separator and the extraction separator integrally, it is possible to remarkably increase the extraction efficiency of supercritical carbon dioxide and / or liquid carbon dioxide in the extraction separation process. As a result, the volume of the solvent used, the extraction time, the capacity and size of the apparatus can be greatly reduced. On the other hand, in the present invention, the specific gravity difference separation and the extraction separation can be appropriately performed in separate systems.

  In the present invention, in the solid-liquid separation method, the solid-liquid mixed substance and supercritical carbon dioxide and / or liquid carbon dioxide are mixed, and after mixing the solid-liquid mixed substance and supercritical carbon dioxide and / or liquid carbon dioxide, The density and viscosity of the fluid are controlled, and the solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are mixed in advance to control the density and viscosity of the fluid. It is a preferred embodiment that liquid separation and supercritical carbon dioxide and / or liquid carbon dioxide mixed with a solid-liquid mixed material are obtained by circulating and reusing fluid after solid separation.

  In the present invention, it is possible to install a circulation mechanism composed of a closed system that recirculates as liquid carbon dioxide through evaporation, cooling, and condensation without exhausting the carbon dioxide. Can be used repeatedly. Further, in the present invention, the solid-liquid mixed substance is continuously separated from the solid-liquid mixed substance by continuously performing the operations of charging the solid-liquid mixed substance, specific gravity difference separation and extraction separation, and solid-liquid separation and recovery with a flow-type apparatus. And a device can be constructed.

  In the present invention, as a solid-liquid mixed substance separation apparatus, a supercritical carbon dioxide and / or liquid carbon dioxide is used as a specific gravity difference separation solvent, and a solid-liquid mixed substance is separated using specific gravity difference separation. And means for introducing supercritical carbon dioxide and / or liquid carbon dioxide at a predetermined position of the separator and means for introducing a solid-liquid mixed material, and means for adjusting the temperature in the system of the separator. Therefore, it is possible to construct a solid-liquid mixed substance separation device.

  In the present invention, preferably, in the separation apparatus, in the supercritical carbon dioxide, a heating means for liquid carbon dioxide for sending liquid carbon dioxide or supercritical carbon dioxide to the lower part of the separator. Means, a pressure means for sending the solid-liquid mixed material to the intermediate part of the separator, a means for storing the solid substance separated by the specific gravity difference at the bottom of the separator, and a separation solvent flowing out from the top of the specific gravity difference separator; Separation, collection and recovery of solid-liquid mixed substances such as slurry waste liquid using a device comprising means for filtering liquid substances, means for adjusting pressure in the system, and gas-liquid separation means for separating the separation solvent and liquid substances A reuse system can be constructed.

  Further, in the present invention, there is provided a separation apparatus that separates a solid-liquid mixed material using a specific gravity difference and extraction separation using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent and an extraction separation solvent. The specific gravity difference separation unit and the extraction separation unit are included in the same vertical system, the extraction separation unit is installed in the lower part and the specific gravity difference separation unit is installed in the upper part, and supercritical carbon dioxide and / or Or a means for introducing liquid carbon dioxide and a means for introducing a solid-liquid mixed substance into a predetermined position of the specific gravity difference separation unit, and a means for adjusting the temperature in the system of the separator. A solid-liquid mixed material separation apparatus can be constructed.

  In the present invention, preferably, in the separation apparatus, the liquid carbon dioxide pressurizing means for sending liquid carbon dioxide or supercritical carbon dioxide, supercritical carbon dioxide is provided below the extraction separation unit. The means for heating, the means for sending the solid-liquid mixed material to the intermediate part of the specific gravity difference separation part, the means for storing the solid substance separated by the specific gravity difference separation part and the extraction separation part at the bottom of the separator, the specific gravity difference separation Using a device equipped with a means for filtering the separation solvent and liquid substance flowing out from the top of the section, a means for adjusting the pressure in the system, and a gas-liquid separation means for separating the separation solvent and the liquid substance, slurry waste liquid etc. It is possible to construct a system for separating, recovering and reusing solid-liquid mixed materials.

  In this case, it is also possible to appropriately install in the above system a solvent circulation mechanism in which the separation solvent is recovered as a gas by an evaporation means for separating the separation solvent and the liquid component, and recirculated as liquid carbon dioxide through cooling and condensation. . In addition, a means for continuously discharging the collected solid substance can be provided at the lower part of the separator. This continuous discharge eliminates the need for solid material storage in the separator, which directly leads to a reduction in the size of the separator. In the present invention, the specific configuration of each means constituting the apparatus is not particularly limited, and can be arbitrarily designed according to the type of solid-liquid mixed substance, the purpose of use of the apparatus, and the like.

  Furthermore, in the present invention, the apparatus used in the above-mentioned solid-liquid separation method is a means for mixing a solid-liquid mixed material with supercritical carbon dioxide and / or liquid carbon dioxide, and controls the density and viscosity of the fluid after mixing. A mixing control device having density and viscosity adjusting means, and a solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are mixed in advance, and the mixture is placed in the specific gravity difference separation region while controlling the density and viscosity of the fluid. It is possible to construct a mixed supply control device to be supplied and a circulation device having a fluid circulation means for circulating and reusing the fluid after solid-liquid separation.

  Conventionally, various methods for recovering and reusing usable SiC and coolant contained in a large amount in a slurry waste liquid generated in a silicon wafer manufacturing process have been tried. However, in any method, it is necessary to use a large amount of organic solvent, strong acid / strong alkali, dilute alkaline aqueous solution, surfactant, etc., or to use a special treatment such as ultrasonic irradiation. Actually, in reality, there is almost no recovery of valuable materials from the slurry due to the necessity of processing the waste liquid. In addition, a method for recovering valuable materials in slurry waste liquid using supercritical carbon dioxide as an extraction solvent has been proposed as an alternative to the extraction method using existing organic solvents. In order to achieve this, a large amount of extraction solvent is required, and there are significant restrictions on downsizing the apparatus, improving the extraction efficiency and the recovery rate of valuable materials.

  Moreover, in the conventional specific gravity difference separation method, a centrifugal separator or the like is used. However, with this type of method, separation efficiency is poor and complete separation is not possible. In order to improve the separation efficiency, there is a method of diluting the solvent. However, after the separation, it is necessary to separate the diluted solvent from the target substance and to perform a post-treatment of the diluted solvent. In contrast, the present invention is characterized by separating solid-liquid mixed substances using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent or using a specific gravity difference separation solvent and an extraction solvent. To do. In the present invention, carbon dioxide, which is a gas at normal temperature and pressure, is used as the specific gravity difference separation solvent, so that the solvent does not remain in the separated material and there is no need for post-treatment. In particular, the density of supercritical carbon dioxide can be easily changed by changing the temperature and pressure, and it is overwhelming by the separation solvents such as water, alcohol, and organic solvents that were used in the conventional specific gravity difference separation. Since the viscosity is low, high separation efficiency can be obtained. In addition, since the density of supercritical carbon dioxide can be changed easily by changing the temperature, for example, after separating the target substance separated by specific gravity roughly in the same system, the target substance that could not be separated by the specific gravity difference is extracted. Separation is possible, resulting in a high separation efficiency that overwhelms the prior art supercritical carbon dioxide extraction.

  That is, in the present invention, supercritical carbon dioxide and / or liquid carbon dioxide is used as a specific gravity difference separation solvent, or a specific gravity difference separation solvent and an extraction solvent, thereby greatly reducing the amount of solvent used and reducing the size of the apparatus. And improvement of separation efficiency of valuable materials can be achieved at the same time. The present invention is a method for separating a specific value in a solid-liquid mixture by using a specific gravity difference separation and / or extraction separation using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent and / or an extraction separation solvent. It is useful as providing an efficient separation method.

The following effects are exhibited by the present invention.
(1) By using supercritical carbon dioxide (SC-CO ₂ ) and / or liquid carbon dioxide as a specific gravity difference separation solvent and extraction solvent, solid-liquid separation and extraction operations can be performed efficiently, and the particle size distribution is uniform from the solid matter. Can be separated and recovered efficiently.
(2) Reusable valuable components can be separated and recovered from the slurry waste liquid by solid-liquid separation and specific gravity difference separation.
(3) According to the present invention, for example, it is possible to construct a recycling process of silicon slurry waste liquid.
(4) In the present invention, a high extraction efficiency of 3 times or more can be obtained as compared with the extraction efficiency of the solid-liquid separation method by SC-CO ₂ extraction.
(5) Since carbon dioxide, which is a gas at normal temperature and pressure, is used as the separation solvent for specific gravity difference, there is an advantage that the solvent does not remain in the separated substance and there is no need for post-treatment.
(6) The density of supercritical carbon dioxide can be easily changed by changing the temperature and pressure, whereby the specific gravity difference separation and / or extraction separation conditions corresponding to the density of the substance to be treated can be set. It is possible to set arbitrarily.
(7) Supercritical carbon dioxide, which is a specific gravity difference separation solvent, has a very low viscosity as compared with water, organic solvents, and the like, and therefore, very high separation efficiency can be obtained.
(8) Carbon dioxide, which is a specific gravity difference separation solvent, can be easily changed in density and viscosity by changing temperature and pressure, and arbitrarily set density and viscosity conditions according to the material to be treated. Can do.

  Next, embodiments of the present invention will be specifically described with reference to the accompanying drawings. Below, an example of embodiment of the highly efficient separation apparatus of the solid-liquid mixture by a supercritical carbon dioxide is shown.

  This apparatus is an example of an embodiment of a high-efficiency separation apparatus for a solid-liquid mixture according to the present invention, and FIG. is there. In the figure, a specific gravity difference separator / extractor main body 1 is a vertical continuous specific gravity difference separator / extractor, and is a separator that performs specific gravity difference separation and extraction simultaneously. As shown in FIG. 1, supercritical carbon dioxide is sent from the lowermost part of the specific gravity difference separation / extractor body 1, and from the uppermost part of the specific gravity difference separation / extractor to outside the system of the specific gravity difference separation / extraction body 1. Discharged.

  The specific gravity difference separation / extractor body 1 has a specific gravity difference separation unit 2 in the upper layer, and a lower layer is provided with an extraction unit 3 provided with a stirrer 10. Further, a high-pressure metering pump 4 for transferring a solid-liquid mixed material for supplying a solid-liquid mixed material to be separated to the center of the specific gravity difference separation unit 2 and a solid-liquid mixed material storage tank 5 are provided. Furthermore, below the specific gravity difference separator / extractor body 1, there is provided a solid matter recovery device 11 for continuously recovering the separated solid matter with running water. In the solid matter recovery device 11, water is supplied by the high-pressure metering pump 8, and the continuously discharged solid matter is continuously recovered as a water slurry. The back pressure valve 9 controls the liquid level to be constant so that water and water slurry do not enter the specific gravity difference separator / extractor body 1.

  The specific gravity difference separator / extractor body 1 has a specific gravity difference separation unit 2 and an extraction unit 3 in the same system, the temperature of the specific gravity difference separation unit 2 is controlled by the heater 6, and the temperature of the extraction unit is controlled by the heater 7. Thus, the density of supercritical carbon dioxide can be set for each. In the specific gravity difference separation unit 2, the density of supercritical carbon dioxide suitable for specific gravity difference separation is set, and the extraction unit 3 is used for extraction. Each can be set to a suitable supercritical carbon dioxide density or temperature.

  FIG. 2 is an overall flowchart of an example of the present embodiment. The solid-liquid mixture high-efficiency separation apparatus of this embodiment includes a carbon dioxide supply line for supplying carbon dioxide to a specific gravity difference separation / extraction device, and a specific gravity difference separation / extraction device body 1, and also has a specific gravity difference separation / extraction. Under the vessel, the solids recovery device 11 that recovers the separated solids with water slurry, and further, the separation liquid and carbon dioxide are recovered from the top of the specific gravity difference separation / extraction device, and the separation liquid and carbon dioxide are separated respectively. This is a high-efficiency separator for a continuous solid-liquid mixture of a carbon dioxide circulation type constituted by a gas-liquid separator for recovery. The condenser 15 cools the gaseous carbon dioxide separated and recovered from the gas-liquid separator I23 and the gas-liquid separator II28 and the liquid carbon dioxide replenished from the liquefied carbon dioxide cylinder 13 with the cooling device 14, and stores them. Furthermore, the condenser 15 is equipped with a liquid level meter, a thermometer, and a pressure gauge, and can always store a certain amount of liquid carbon dioxide.

  The carbon dioxide supply line precools the liquid carbon dioxide stored in the condenser 15 with the precooler 16 and transfers the liquid carbon dioxide with the high-pressure metering pump 17. Further, the liquid carbon dioxide transferred by the high-pressure metering pump 17 is supplied to the specific gravity difference separator / extractor body 1 via the flow meter 18 and the heater 19. Further, by varying the discharge flow rate of the high-pressure metering pump 17, it is possible to control the separation efficiency of the solid-liquid mixture by the supercritical carbon dioxide flow rate.

  The solid matter recovery device 11 is disposed under the specific gravity difference separator / extractor body 1 and supplies water with the high-pressure metering pump 8 to continuously recover the separated solid matter as a water slurry. The flow rate of the recovered water slurry is controlled by the high-pressure metering pump 8, and the liquid level is kept constant by the back pressure valve 9 so that water and water slurry do not enter the specific gravity difference separator / extractor body 1. Control.

  The separation liquid and carbon dioxide transferred from the top of the specific gravity difference separator / extractor body 1 are filtered by the high-pressure filter 20 to collect a small amount of solids transferred together with the separation liquid and carbon dioxide, and the separation liquid And only carbon dioxide is discharged to the subsequent stage. The separation liquid and carbon dioxide that have passed through the high-pressure filter 20 are depressurized by the back pressure valve 21, further heated by the heater and line heater 24 installed in the back pressure valve 21, and transferred to the gas-liquid separator I 23.

  The separation liquid and carbon dioxide transferred to the gas-liquid separator I23 are heated again by the heater 30, the gaseous carbon dioxide is transferred to the activated carbon 31, and the separation liquid is transferred to the gas-liquid separator II28. The separated liquid transferred to the gas-liquid separator II28 is reheated by the heater 29 to completely vaporize carbon dioxide, transfer the gaseous carbon dioxide to the activated carbon 31, and capture the separated liquid in the gas-liquid separator II28. Gather. The separated liquid collected in the gas-liquid separator II28 can be taken out during continuous operation by operating the valve 25, the valve 26, and the valve 27. The gaseous carbon dioxide transferred from the gas-liquid separator I23 and the gas-liquid separator II28 becomes vapor together with the gaseous carbon dioxide by the activated carbon 31 and collects the separated separated liquid, and only the gaseous carbon dioxide is collected in the subsequent condenser 15. Transport to.

  Next, the present invention will be specifically described based on comparative experiments and examples, but the present invention is not limited to the following examples.

Comparative experiment (1) SC-CO ₂ extraction test apparatus In this comparative example, an extractor (capacity 75 ml, manufactured by SU316) equipped with a heater and a stirrer, a back pressure valve, a gas-liquid separator, a CO ₂ cylinder, and CO ₂ are cooled. A SC-CO ₂ extraction device composed of a cooler and a metering pump was used. FIG. 3 shows an outline of the SC-CO ₂ extraction apparatus. In this device, the liquid CO ₂ which is transported by the metering pump is turned SC-CO ₂ at extractor contacts the slurry waste fluid sample, the coolant from the extractor together with SC-CO ₂ was dissolved in SC-CO ₂ Go out and the solid material remains. The SC-CO ₂ exiting the extractor becomes atmospheric pressure after the back pressure valve, the coolant is separated by the gas-liquid separator, and the CO ₂ is separated and discharged out of the system.

(2) Sample and separation test flow In this comparative example, a slurry waste liquid consisting of SiC: 48 wt%, silicon chip: 9 wt%, iron scrap: 4 wt%, coolant (mineral oil): 39 wt% was used as a sample. The test flow in this comparative example is shown in FIG.

(3) SC-CO ₂ extraction test 26 g of slurry waste liquid was charged into the extractor, and liquid CO ₂ was sent to the extractor at a set pressure (10 to 34 MPa). The extractor was heated to 35 ° C. or 150 ° C., and extraction was started. At an extraction temperature of 35 ° C., extraction was performed by circulating SC-CO ₂ at 5.9 g / min for 60 min. On the other hand, at 150 ° C., extraction was performed by circulating SC-CO ₂ at 5.9 g / min for 120 min.

(4) SiC recovery test After taking out the solid material solid-liquid separated with SC-CO ₂ to the outside, the aqueous solution containing the surfactant is added to the recovered solid material, mixed, and allowed to stand, thereby leaving silicon chips. , Iron scraps, etc. moved to the supernatant, and SiC precipitated in the lower part. The precipitated SiC was left, the floating silicon chips were separated as a supernatant, and the iron scrap was collected by a magnet in the same process. By repeating this operation a plurality of times, SiC was recovered.

(5) Results FIG. 5 shows the relationship between the coolant recovery rate and the operating pressure. The coolant recovery rate is expressed by the extracted coolant amount × 100 / the coolant amount in the slurry waste liquid. As shown in the figure, the coolant recovery rate was 90% or more at 35 ° C. and 20 MPa or more, and 150 ° C. and 34 MPa. However, as shown in FIG. 6 (relationship between the coolant extraction rate and the CO ₂ density), the coolant extraction rate (the amount of extracted coolant / the amount of CO ₂ used) has a remarkable effect of increasing the CO ₂ density. Although there is a maximum, it is as low as 0.03 g coolant / gCO ₂ or less, and it has become clear that simple extraction separation is not economical.

  FIG. 7 shows the particle size distribution of the recovered SiC. The recovered SiC is free of silicon chips and iron scrap, and the slurry waste liquid also contains a lot of crushed and unnecessary SiC fine powder. It was revealed that SiC can be eliminated and SiC having a uniform particle size can be obtained.

  In this example, the slurry waste liquid was separated using a separation apparatus in which a separator and an extractor based on a specific gravity difference were provided in the same system. The composition of the slurry waste liquid was 48 wt% for SiC, 9 wt% for silicon chips, 4 wt% for iron scrap, and 39 wt% for coolant (mineral oil). FIG. 8 shows a schematic diagram of the separation apparatus used in this example. In the figure, 1 is a solid-liquid mixture separation device main body (specific gravity difference separation / extraction device main body), 2 is a specific gravity difference separation part by specific gravity difference separation, 3 is an extraction part by solvent extraction, and 4 is a high-pressure determination in which slurry is injected. Pumps, 5 are slurry storage tanks (solid-liquid mixed substance storage tanks), 16 and 17 are precoolers for precooling and pressurizing liquid carbon dioxide, high pressure pumps, 19 are preheaters, and 6 and 7 are supercritical carbon dioxides. A heater for adjusting the temperature of the fluid, 20 is a high pressure filter, 21 is a back pressure valve for controlling the pressure, and 28 is a gas-liquid separator II.

The liquid CO ₂ is sent to the separation apparatus main body 1 until the set pressure (20 MPa) is reached, and after the flow rate is adjusted to the set value (1 kg / h), heating of the heater 19 and the heaters 6 and 7 is started. Heating was continued until the temperature reached the set temperature. In this experiment, both the specific gravity difference separation unit 2 and the extraction unit 3 were set to 40 ° C., and the heating was controlled so as to maintain the temperature after reaching. After confirming that the temperature and pressure reached the set values and were stable, the slurry waste liquid supply was started at the set values (0.2 kg / h). Immediately after the operation, the coolant moved upward, the solid matter such as SiC moved downward, the coolant was held at the bottom of the gas-liquid separator II28, and the solid matter was held at the bottom of the extraction unit 3.

  The operation was performed for 1 hour after the temperature and pressure conditions were stabilized, and the supply of slurry waste liquid was stopped. The supply of supercritical carbon dioxide to the separator 1 was continued for a while even after the waste liquid supply was stopped, and the coolant in the separator 1 was discharged. Thereafter, the heating was stopped, and the pressure in the separator 1 was reduced until the pressure became atmospheric pressure. After confirming the pressure in the separator 1, the solid substance storage part at the lower part of the extraction part 3 was released, and the solid substance was collected. The extraction rate was determined by subtracting from the amount of coolant supplied by evaluating the amount of coolant in the solid. The amount of carbon dioxide used was the integrated value of a mass flow meter provided after the gas-liquid separator II28.

  In the above separation operation, solid waste separation of waste slurry generated in the slicing process of silicon ingot is performed, and the extraction efficiency in the case of solid-liquid separation only by supercritical carbon dioxide extraction separation is combined with specific gravity difference separation and extraction separation. The extraction efficiencies when separated in different systems were compared. The result is shown in FIG. As shown in the figure, it was found that extraction efficiency of 3 times or more can be obtained by solid-liquid separation using a system combining specific gravity difference separation and extraction separation.

  In this example, the slurry waste liquid was separated using a separation apparatus provided with a system for mixing a solid-liquid mixed substance and supercritical carbon dioxide in a high-pressure pipe. The composition of the slurry waste liquid was SiC 50%, silicon chips, Fe scrap 19%, and coolant 31%. FIG. 10 shows a schematic diagram of the separation apparatus used in this example. In the figure, 1 is a solid-liquid separator main body (specific gravity difference separator / extractor main body), 4 is a high-pressure pump (high-pressure metering pump) for press-fitting slurry, 5 is a slurry storage tank (solid-liquid mixed substance storage tank), 16 , 17 is a precooler for precooling and pressurizing liquid carbon dioxide, a high pressure metering pump, 19 is a preheater, 6 and 7 are heaters for adjusting the temperature of the supercritical carbon dioxide fluid, and 20 is a high pressure filter. 21 is a back pressure valve for controlling pressure, and 28 is a gas-liquid separator II.

While the liquid CO ₂ is sent from the in-system cleaning line 36 to the solid-liquid separator main body 1 until the set pressure (29 MPa) is reached, the preheater 19 and the heaters 6 and 7 are heated to reach the set temperature (35 ° C.). The heating was continued until the temperature reached, and the temperature was controlled so as to maintain the temperature after reaching the temperature. The CO ₂ was adjusted to set the flow rate (0.6 kg / h) together with the control of pressure and temperature, were supplied CO ₂ from the slurry CO ₂ mixing line 35 further CO ₂ inlet by switching the valve 32 and the valve 33 . Thereafter, the valve 34 was opened to supply a set amount (0.14 kg / h) of slurry waste liquid. The coolant was discharged from the upper part of the solid-liquid separator main body 1 along with CO ₂ and collected by the gas-liquid separator II28. The solids of SiC, silicon chips, and Fe scrap were collected in the lower solids recovery device 11.

The operation is performed for about 4 hours from the start of the supply of the slurry waste liquid. After the supply of the slurry is stopped, the valve 32 is opened, the valve 33 is closed, and the CO ₂ supply is switched to the in-system cleaning line. The coolant in the solid-liquid separator main body (specific gravity difference separator / extractor main body) 1 was discharged. Thereafter, the heating was stopped, and the pressure in the solid-liquid separator main body 1 was reduced until the pressure became atmospheric pressure. After depressurization, the solid matter recovery device 11 was opened and the solid matter was collected. At each location of the solid matter recovery device 11, the high-pressure filter 20, and the gas-liquid separator 28, the recovery amount with respect to the total supply amount of each substance of SiC, silicon chips, Fe scrap, and coolant was evaluated.

  In the above separation operation, the slurry waste liquid generated in the slicing process of the silicon ingot and supercritical carbon dioxide are mixed, and the coolant in the slurry waste liquid is reduced in density and viscosity so that the solids in the slurry waste liquid can be efficiently used. It was found that it was possible to settle and separate. FIG. 11 shows the recovered substance and recovery rate at each point.

  As described in detail above, the present invention relates to a method and apparatus for separating a solid-liquid mixed material with high efficiency by combining extraction separation with supercritical carbon dioxide and / or liquid carbon dioxide and specific gravity difference separation. According to the present invention, it is possible to separate and recover a reusable substance from a solid-liquid mixed substance with a high separation efficiency far exceeding that of the conventional supercritical carbon dioxide extraction method. In addition, according to the present invention, supercritical carbon dioxide and / or liquid carbon dioxide is used to control the density and viscosity of the medium contained in the solid-liquid mixed material, thereby far exceeding the conventional supercritical carbon dioxide extraction method. Solid-liquid mixed substances can be separated with separation efficiency, and it is possible to recover reusable substances. The present invention can be applied to, for example, a solid-liquid separation of slurry waste liquid such as silicon slurry waste liquid and a recycling process of useful materials that can be reused, and a high-efficiency separation method for general solid-liquid mixtures. It has a high technical significance as providing a high-efficiency separation technique for a new solid-liquid mixture.

A preferred embodiment (specific gravity difference / extraction separator) is shown. A preferred embodiment (overall configuration) is shown. It shows a schematic diagram of a SC-CO ₂ extraction test apparatus used in Comparative Example. The test flow in a comparative example is shown. The relationship between the coolant recovery rate and the operating pressure is shown. It shows a coolant extraction rate and CO ₂ density relationship. The particle size distribution of recovered SiC is shown. The schematic diagram of the separation apparatus which performs specific gravity difference separation and extraction separation simultaneously in the same system is shown. It shows the comparison results of the separation efficiency of the waste slurry by SC-CO _2. The schematic of the separation apparatus used in Example 2 is shown. The recovered material and the recovery rate at each point when the separation operation is carried out using the separation apparatus are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Specific gravity difference separation / extractor body 2 Specific gravity difference separation part 3 Extraction part 4 High-pressure metering pump 5 Solid-liquid mixed substance storage tank 6 Heater 7 Heater 8 High-pressure metering pump 9 Back pressure valve 10 Stirrer 11 Solid matter collection device 12 Safety valve 13 Liquefaction carbonic acid Gas cylinder 14 Cooling device 15 Condenser 16 Precooler 17 High pressure metering pump 18 Flow meter 19 Heater 20 High pressure filter 21 Back pressure valve 22 Safety valve 23 Gas-liquid separator I
24 Line heater 25 Valve 26 Valve 27 Valve 28 Gas-liquid separator II
30 Heater 31 Activated carbon 32 Valve 33 Valve 34 Valve 35 Slurry CO ₂ mixing line 36 In-system cleaning line

Claims (26)

  A method for separating a solid-liquid mixed material, wherein supercritical carbon dioxide and / or liquid carbon dioxide is used as a specific gravity difference separation solvent, and the solid-liquid mixed material is separated using the specific gravity difference.   The method for separating a solid-liquid mixed material according to claim 1, wherein the solid-liquid mixed material is a slurry waste liquid.   The method for separating a solid-liquid mixed material according to claim 2, wherein the slurry waste liquid is a slurry waste liquid generated in a silicon wafer manufacturing process.   The density of the specific gravity difference separation solvent is adjusted by changing the temperature and / or pressure conditions to control the separation efficiency by the specific gravity difference separation, and / or the flow rate of the specific gravity difference separation solvent is adjusted to achieve the separation efficiency by the specific gravity difference separation. The method for separating a solid-liquid mixed material according to claim 1, wherein the solid-liquid mixed material is controlled.   The specific gravity difference separation step according to claim 1 is combined with the extraction separation step using supercritical carbon dioxide and / or liquid carbon dioxide as an extraction separation solvent, and the solid-liquid mixed substance is utilized by specific gravity difference separation and extraction separation. And separating the solid-liquid mixed material.   The solid-liquid mixed material separation method according to claim 5, wherein the specific gravity difference separation and the extraction separation are performed simultaneously in the same system.   The density of the specific gravity difference separation solvent and / or the extraction separation solvent is adjusted by changing the temperature and / or pressure conditions to control the separation efficiency by the specific gravity difference separation and / or the extraction separation, and / or the specific gravity difference separation solvent and 6. The method for separating a solid-liquid mixed material according to claim 5, wherein the separation efficiency by specific gravity difference separation and / or extraction separation is controlled by adjusting the flow rate of the extraction separation solvent.   The solid-liquid mixed material separation method according to claim 5, wherein the specific gravity difference separation and the extraction separation are continuously performed in the same system.   The method for separating a solid-liquid mixed material according to claim 5, further comprising a recycling process for recovering the reusable material separated using specific gravity difference separation and extraction separation.   A separation apparatus that separates a solid-liquid mixed material using specific gravity difference separation using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent, wherein the supercritical carbon dioxide is placed at a predetermined position of the separator. And / or means for introducing liquid carbon dioxide and means for introducing a solid-liquid mixed substance, and further comprising means for adjusting the temperature in the system of the separator, apparatus.   Liquid carbon dioxide pressurizing means for sending liquid carbon dioxide or supercritical carbon dioxide to the lower part of the separator, and in the case of supercritical carbon dioxide, heating means, and a solid-liquid mixed substance is sent to the intermediate part of the separator Pressurizing means, means for storing the solid substance separated by the specific gravity difference at the bottom of the separator, means for filtering the separated solvent and liquid substance flowing out from the top of the specific gravity difference separator, means for adjusting the pressure in the system The solid-liquid mixed substance separation device according to claim 10, further comprising gas-liquid separation means for separating the separation solvent and the liquid substance.   A separation apparatus for separating a solid-liquid mixed material using a specific gravity difference and extraction separation using supercritical carbon dioxide and / or liquid carbon dioxide as a specific gravity difference separation solvent and an extraction separation solvent, comprising a specific gravity difference separation unit, The extraction / separation unit is included in the same vertical system, the extraction / separation unit is installed in the lower part and the specific gravity difference separation unit is installed in the upper part, and supercritical carbon dioxide and / or liquid carbon dioxide is introduced into a predetermined position of the extraction / separation part. And a means for introducing the solid-liquid mixed material into a predetermined position of the specific gravity difference separating section, and further comprising means for adjusting the temperature in the system of the separator. Separation device.   Liquid carbon dioxide pressurizing means for sending liquid carbon dioxide or supercritical carbon dioxide to the lower part of the extraction / separation part, in the case of supercritical carbon dioxide, heating means, solid liquid in the intermediate part of the specific gravity difference separation part Means for sending the mixed substance, means for storing the solid substance separated in the specific gravity difference separation section and the extraction separation section at the bottom of the separator, means for filtering the separation solvent and liquid substance flowing out from the top of the specific gravity difference separation section The apparatus for separating a solid-liquid mixed material according to claim 12, further comprising: means for adjusting the pressure in the system; and gas-liquid separation means for separating the separation solvent and the liquid substance.   13. The solid-liquid mixed substance separation device according to claim 10, further comprising means for individually controlling the temperature in the separator in a plurality of vertical portions.   13. The solid-liquid mixed substance separation device according to claim 10 or 12, wherein the gas-liquid separation device has a separation solvent (liquid carbon dioxide) evaporation means.   The solid-liquid mixed substance separation device according to claim 15, wherein the gas separation solvent (carbon dioxide gas) is converted into liquid carbon dioxide by cooling and condensing, and has a solvent circulation mechanism for recirculation.   14. The solid-liquid mixed substance separation device according to claim 11 and 13, further comprising means for continuously discharging the solid substance collected and stored in the lower part of the separator.   The solid-liquid mixed substance separation device according to claim 17, wherein the solid substance continuous discharging means is a water slurry discharging means by high-pressure water injection.   The apparatus for separating a solid-liquid mixed material according to claim 18, wherein the means for discharging the water slurry by the high-pressure water injection includes a high-pressure solid-liquid separation means.   The solid-liquid mixed substance separation device according to claim 19, wherein the high-pressure solid-liquid separation means is a high-pressure filter or a high-pressure cyclone.   The solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are mixed, and the density and viscosity of the fluid after mixing the solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are controlled. The solid-liquid separation method described.   The solid-liquid separation method according to claim 21, wherein the solid-liquid mixed material and supercritical carbon dioxide and / or liquid carbon dioxide are mixed in advance to control the density and viscosity of the fluid, and then the solid-liquid separation is performed using the difference in specific gravity. .   23. The solid-liquid separation method according to claim 22, wherein the supercritical carbon dioxide and / or liquid carbon dioxide mixed with the solid-liquid mixed material is obtained by circulating and reusing the fluid after the solid separation.   The apparatus used in the solid-liquid separation method according to claim 21, wherein the solid-liquid mixed substance is mixed with supercritical carbon dioxide and / or liquid carbon dioxide, and the density for controlling the density and viscosity of the fluid after mixing. And a viscosity control means.   The apparatus used in the solid-liquid separation method according to claim 21, wherein a solid-liquid mixed substance and supercritical carbon dioxide and / or liquid carbon dioxide are mixed in advance, and the mixture is controlled for density and viscosity of the fluid. A mixture supply control device comprising a mixture supply means for supplying to the specific gravity difference separation region.   The apparatus for use in the solid-liquid separation method according to claim 21, further comprising a fluid circulation means for circulating and reusing the fluid after the solid-liquid separation.