JP2005342630A - Extraction treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means, as the method for treating the soil containing a low-boiling point polluted substance, which is capable of efficiently removing the low-boiling point substance by transferring without oxidizing the substance to a vapor phase by a heating system using a rotary kiln, making the exhaust released in the atmosphere zero or very little, making treating equipment decreased in size and closed, and remarkably reducing equipment cost and treatment cost. <P>SOLUTION: A treating object D<SB>1</SB>containing the low-boiling point substance is continuously fed into the rotary kiln 1 to be carried to the side of an outlet 1b and the rotary kiln 1 is heated at inside by filling it with superheated steam S1 being supplied continuously from outside so as to extract the low-boiling point substance in the treating object D<SB>1</SB>to the vapor phase side, and a treating object D<SB>2</SB>undergone the extraction is continuously taken out. The exhaust S2 from the rotary kiln 1 is cooled to a temperature lower than that of the treating object D<SB>1</SB>fed to the rotary kiln 1 and condensed so as to take the extracted low-boiling point substance into a condensate W2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a treatment method for extracting low-boiling substances from various objects to be treated including low-boiling substances such as soil contaminated with mercury and its compounds and low-boiling organic substances.

  Conventionally, heat treatment using a direct heating or indirect heating rotary kiln is generally used as a purification treatment for contaminated soil, etc., but it requires advanced exhaust gas treatment to generate a large amount of exhaust gas, and there are also facilities. There is a problem in that it is large and complicated, the processing cost and the equipment cost are high, and the transportation cost for transporting the contaminated soil from the contaminated area to the treatment plant is increased. Of course, direct heating is a matter of course, and even in indirect heating, the processing space tends to be in an oxidizing atmosphere, which makes it difficult to recover due to oxidation of contaminants and complicates the processing process for recovery. It was.

  In view of the above circumstances, the present invention oxidizes low-boiling substances in an object to be processed by a heating method using a rotary kiln as a method for treating various objects including low-boiling substances including the contaminated soil. The gas can be transferred to the gas phase without being removed and efficiently removed, and the exhaust emission to the atmosphere is reduced to zero or minimal, enabling the processing equipment to be downsized and closed, thereby significantly reducing equipment costs and processing costs. It aims to provide a means to obtain.

In order to achieve the above object, according to the first aspect of the present invention, the object to be treated D ₁ containing a low-boiling substance is continuously fed into the rotary kiln 1 to the outlet 1b side. While being conveyed, the rotary kiln 1 is filled with the superheated steam S1 continuously supplied from the outside and heated to extract low-boiling substances in the object D1 to the gas phase side, and the object D2 after extraction is extracted. The exhaust gas S2 from the rotary kiln 1 is cooled to a temperature equal to or lower than the temperature of the workpiece D1 supplied to the rotary kiln 1 to condense the extracted low-boiling substances into the condensate W2. The summary is an extraction processing method characterized by the above.

  According to a second aspect of the present invention, in the extraction processing method of the first aspect, the negative pressure generated along with the condensation of the exhaust gas is used as power for introducing the superheated steam S1 into the rotary kiln 1.

  According to a third aspect of the present invention, in the extraction method of the first or second aspect, the rotary kiln 1 has a double cylinder structure of a porous inner cylinder 11 and an outer cylinder 12, and is introduced between the inner and outer cylinders 11 and 12. The heated superheated steam S1 is supplied into the processing space 10 of the rotary kiln 1 through the hole (the vent hole 14) of the inner cylinder 11.

  The invention of claim 4 is the extraction processing method of claim 3, further comprising a superheated steam supply pipe line 20 disposed along the axis in the processing space 10 of the rotary kiln 1 having a double cylinder structure. By introducing the superheated steam S1 between the superheated steam supply conduit 20 and the inner and outer cylinders 11 and 12, the superheated steam S1 is supplied into the processing space 10 from both the peripheral part and the central part, and from the peripheral part. The superheated steam supply amount is set to be larger on the inlet 1a side than the rotary kiln outlet 1b side, and the superheated steam supply amount from the center is set to be larger on the outlet 1b side than on the rotary kiln inlet 1a side.

  The invention of claim 5 is such that the object to be processed D1 in the extraction processing method of any one of claims 1 to 4 is a contaminant due to mercury or / and a low boiling point organic substance.

  Invention of Claim 6 is set as the structure which sets the temperature in the rotary kiln 1 to 110-350 degreeC in the extraction processing method in any one of the said Claims 1-5.

  In the extraction processing method according to the first aspect of the present invention, superheated steam is used as a heat source for transferring the low boiling point substance in the object to be processed into the gas phase, and the processing space of the rotary kiln is filled with the superheated steam. By performing heat treatment and cooling and condensing the exhaust from the rotary kiln below the temperature of the workpiece to be supplied to the rotary kiln, all the low-boiling substances contained in the water vapor that is the main component of the exhaust are liquefied or solidified. Since it can be recovered in liquid form with condensed water (in the case of a non-water-soluble sublimable substance), advanced exhaust gas treatment as in conventional heat treatment is unnecessary, and thus the entire treatment facility can be downsized. Compared to the conventional method, the processing cost and equipment cost can be greatly reduced, and since the remaining gas phase components are almost eliminated, the entire system can be closed. , Yet extractant is downstream of the process is also easy since not subject to oxidation by hot air. Therefore, when the object to be treated is soil contaminated with mercury and its compounds or low-boiling organic substances, the contaminated components can be removed efficiently and at low cost, and the re-scattering of the contaminated components to the environment is ensured. The extracted contaminated components can be easily recycled because they are not oxidized, and the processing residue is not deteriorated by oxidation and returns to the state before contamination. Moisture contained in the processed material is also vaporized and removed and taken out from the rotary kiln as a dry state. Therefore, handling such as transportation and storage is facilitated, and drying as a pretreatment can be omitted at the time of reuse.

  According to the invention of claim 2, since the negative pressure generated as the exhaust gas condenses is used as the power for introducing superheated steam into the rotary kiln, a mechanical device such as a fan for forcibly supplying and discharging superheated steam is used. Equipment can be omitted or reduced in size, and negative pressure is applied to the processing space in the rotary kiln to improve the extraction efficiency, and the pressure in the entire processing space is balanced by the communication between the rotary kiln and the cooling unit that performs condensation. In addition, the extraction speed can be controlled by the supply temperature and the cooling temperature of the superheated steam, and the processing space is in a non-pressurized state, so that the processing apparatus can be designed simply and safely.

  According to invention of Claim 3, in order to supply superheated steam from the whole surrounding part in the processing space of a rotary kiln, a large amount of superheated steam passes through the deposition layer of a to-be-processed object, speeding up temperature rising and high extraction Efficiency is obtained.

  According to the invention of claim 4, since superheated steam is supplied from both the peripheral part and the central part into the processing space of the rotary kiln, the entire processing space can be easily set in an atmosphere optimal for extraction of low-boiling substances. Since the supply amount from the surrounding part is large at the inlet side and the supply amount from the central part is conversely increased at the outlet side, the material to be processed is supplied from the peripheral part at the inlet side where the temperature of the object is low. The amount of superheated steam that passes through the chamber increases, and the extraction temperature of the low-boiling substances increases as the temperature of the material to be processed increases faster. Since it can maintain, it can prevent that a part of extraction component returns in a to-be-processed object by the fall of atmospheric temperature.

  According to the fifth aspect of the present invention, it is possible to efficiently extract and remove the pollutant components by using the pollutants due to mercury or low boiling point organic substances as a treatment target.

  According to the invention of claim 6, since the inside of the rotary kiln is set to a specific temperature range, the extraction efficiency of low-boiling substances in the object to be processed is increased, and unnecessary thermal decomposition and thermal alteration of other components are suppressed. be able to.

  Embodiments of the present invention will be specifically described below with reference to the drawings. 1 is a schematic configuration diagram of a processing apparatus to which an extraction processing method according to an embodiment of the present invention is applied, FIG. 2 is a side view of the processing apparatus, FIG. 3 is a longitudinal side view of a rotary kiln portion of the processing apparatus, FIG. FIG. 4 is a sectional view taken along line AA in FIG. 3.

  In FIG. 1, reference numeral 1 denotes a rotary kiln that performs an extraction process, an inner cylinder 11 that is rotationally driven via a motor M <b> 1, and a non-rotating outer cylinder 12 that is fitted on the outer peripheral portion excluding both ends of the inner cylinder 11. A stirring shaft 2 is disposed in the inner cylinder 11 along the axial direction thereof. A screw feeder 3 that continuously feeds the workpiece D1 charged into the hopper 31 into the inner cylinder 11 is provided on the inlet 1a side of the rotary kiln 1, and on the outlet 1b side, exhaust S2 and after extraction processing are provided. An exhaust separation tank 4 for separating the processing residue D2 is provided. 32 is a chemical injection port attached to the screw feeder 3 located downstream of the hopper 31, 5 is a superheated steam generator for generating superheated steam S 1 higher than raw water W 1 such as tap water, and 6 is from the rotary kiln 1. A cooling device 7 for cooling and condensing the exhaust S2 is an activated carbon filling tank.

  As shown in FIG. 3, sealing members 13 that are in sliding contact with the inner cylinder 11 in an airtight state are fitted to both ends of the outer cylinder 12 of the rotary kiln 1. An annular space 15 sealed is formed, and a steam introduction pipe 5a from the superheated steam generator 5 is branched into and communicated with the annular space 15 into an inlet 1a side and an intermediate portion as shown in FIG. ing. Further, a large number of vent holes 14 are provided in a peripheral surface region of the inner cylinder 11 surrounded by the outer cylinder 12, and the superheated steam S1 introduced into the annular space 15 is introduced into the inner cylinder 11 from the vent holes 14. Are discharged into the processing space 10. A heat insulating material layer 16 is provided on the outer peripheral surface of the outer cylinder 12.

  Thus, the inner cylinder 11 has annular rails 17 fixed to the outer peripheral surfaces of both end portions exposed to the outside, and each annular rail 17 is free to play by a pair of rollers 18 and 18 as shown in FIGS. The rotary kiln 1 is rotatably supported and is driven to rotate via a chain 8 wound between a driven sprocket 19 provided on the outer peripheral surface of the end portion on the outlet side of the rotary kiln 1 and a driving sprocket of the motor M1. Although the rotary kiln 1 is illustrated as a horizontal posture in FIGS. 1 to 3, the rotary kiln 1 is actually installed in an inclined state in which the outlet 1 b side is lowered, and the object to be processed in the processing space 10 is rotated with the rotation of the inner cylinder 11. The object D1 is conveyed to the exit 1b side by the gravitational action based on the inclination.

  As shown in FIG. 3, the agitation shaft 2 has a hollow pipe shape and is provided with cylindrical agitation blades 21... Protruding in a radial direction at a plurality of locations in the longitudinal direction (4 locations in the figure). It is integrated with the feeder shaft 3a of the screw feeder 3 and is driven to rotate integrally with the screw feeder 3 via a motor M2 shown in FIGS. And the other end 2b side of the stirring shaft 2 penetrates the exhaust separation tank 4 and protrudes to the outside, and the protruded other end 2b is connected to the steam introduction pipe 5b from the superheated steam generator 5 so as to be relatively rotatable, Further, as shown in FIG. 3, a large number of vent holes 22 are formed on the peripheral surface of each stirring blade 21, and the stirring shaft 2 causes the superheated steam S1 introduced from the vent holes 22 of the stirring blade 21 to pass through. A superheated steam supply pipe 20 that discharges to the processing space 10 of the rotary kiln 1 is configured.

  Here, the air holes 14 in the inner cylinder 11 of the rotary kiln 1 and the air holes 22 in the respective stirring blades 21 of the stirring shaft 2 are both formed by electron beam drilling, and straight inside and outside the vessel wall. It is transparent to the shape. Therefore, the hole diameters of the two air holes 14..., 22... Are generally in the range of about 0.1 to 3 mm, but the hole diameter of the air holes 14 of the inner cylinder 11 is the inlet of the rotary kiln 1 continuously or stepwise. On the other hand, the diameter of the vent holes 22 of the stirring blade 21 is set so as to increase toward the stirring blade 21 on the outlet 1b side of the rotary kiln 1.

  As shown in FIG. 3, the exhaust separation tank 4 includes an intermediate separation chamber 4a through which the stirring shaft 2 passes, an upper gas collection chamber 4b loaded with a bag filter 41, and a lower processing residue duct 4c. ing. In the separation chamber 4a, the end of the rotary kiln 1 on the outlet 1b side, that is, the opening end 11a of the inner cylinder 11 is plunged through the sealing material 13 and is a disk-shaped member fixed to the stirring shaft 2. The baffle plate 42 is disposed so as to face the end opening 11a of the inner cylinder 11, and the flow of the exhaust gas S2 from the processing space 10 is blocked by the baffle plate 42 and once turned downward, and then turned upward and turned back. It is guided so as to rise further, so that the powder particles of the processing residue D1 accompanying the exhaust S2 are reduced and directed to the upper gas collection chamber 4b. The powder particles of the processing residue D1 adhering to the front surface of the baffle plate 42 are scraped off by coming into contact with the front surface of the baffle plate 42 where the scraper 43 attached to the separation chamber 4a rotates.

  The processing residue duct 4c has a shape narrowed downward, and its lower part is connected to an introduction port 45a of the screw feeder 45 through a damper 44 as shown in FIG. The screw feeder 45 constitutes an upwardly inclined cylindrical carry-out path, and is provided with a cooling jacket 46 for circulating a refrigerant C such as cooling water on the outer periphery.

  As shown in FIG. 1, the cooling device 6 introduces the exhaust gas from which dust has been removed through the bag filter 41 of the gas collection chamber 4b into the cooling chamber 6a through the exhaust introduction pipe 61, and connects the cooling pipe 62 in the cooling chamber 6a. It is condensed by heat exchange with the refrigerant C such as circulating water, and the condensate W2 is led to the lower overflow tank T1 through the discharge pipe 63 with a valve V1 provided at the lower end, and further from the overflow tank T1. It overflows and is stored in the condensate recovery tank T2 on the side. Note that the lower end of the discharge pipe 63 is located below the overflow level in the overflow tank T1, and the outlet side of the cooling chamber 6a is sealed with water when the valve V1 is opened. Further, the top of the cooling chamber 6a is connected to the activated carbon filling tank 7 by an exhaust pipe 9a having a valve V2, and an exhaust pipe 9b with a fan F is led out from the activated carbon filling tank 7.

  In the extraction processing method of the present invention using the processing apparatus having the above-described configuration, an object to be processed D1 such as soil containing low-boiling point contaminants such as low-boiling point metals such as mercury and its compounds and low-boiling point organic substances is charged into the hopper 31. The superheated steam S1 generated by the superheated steam generator 5 is continuously fed into the inner cylinder 11 of the rotary kiln 1 by the screw feeder 3 while the superheated steam supply pipe of the annular space 15 between the inner and outer cylinders 11 and 12 and the stirring shaft 2 is used. Introduce into the road 20 continuously. Thus, the processing space 10 in the inner cylinder 11 is always filled with the superheated steam S1 released from the vent holes 14 of the inner cylinder 11 and the vent holes 22 of the stirring blade 21. In addition, what is necessary is just to set the temperature of superheated steam S1 according to the kind of to-be-processed object D1 in the range of 150-350 degreeC generally, and when the to-be-processed object D1 is the said soil, it is set to about 300 degreeC. Good.

  The workpiece D1 sent into the inner cylinder 11 is repeatedly accumulated and dropped by the rotation of the inner cylinder 11 in the processing space 10 filled with the superheated steam S1, and the stirring action by the stirring blade 21 of the rotating stirring shaft 2 As the surface is renewed, it is transported along the inclination of the rotary kiln 1 to the outlet 1a side. In this process, the temperature is raised by the heat of the superheated steam S1, so the contained low-boiling contaminants together with the contained moisture It is vaporized and extracted and moves to the gas phase side.

  Therefore, in this extraction process, the release of superheated steam S1 from the surroundings into the processing space 10 increases on the inlet 1a side of the rotary kiln 1 due to the change in the diameter of the vent holes 14 and 22 described above. The discharge of the superheated steam S1 from the central portion into the processing space 10 is set so as to increase on the outlet 1b side. Accordingly, on the inlet 1a side where the temperature of the object to be treated D1 is low, there is a large amount of superheated steam S1 that exits the vent holes 14 and passes through the object to be treated D1. The extraction efficiency of will increase. On the other hand, on the outlet 1b side where the extraction has progressed, the release of superheated steam S1 from the peripheral portion necessary for extraction is reduced, but instead the ambient temperature is constant due to the superheated steam S1 supplied more from the central portion. Since the temperature is maintained at a high temperature, it is possible to reliably prevent a part of the extraction component from returning to the workpiece D1 due to a decrease in the atmospheric temperature.

  In addition, since low boiling point metals such as mercury contained in the contaminated soil are often oxidized, in the treatment of the object to be treated D1 including this, stannous chloride or A suitable reducing agent such as hydrazine may be injected, converted to metal by a reduction reaction in the treatment space 10 of the rotary kiln 1 and vaporized and extracted.

  Thus, the exhaust S2 containing the extracted components reaching the outlet 1b of the rotary kiln 1 and the processing residue D1 are separated in the exhaust separation tank 4, and the processing residue D1 falls and accumulates in the processing residue duct 4c, while the exhaust S2 is a cooling device. 6 is introduced into the cooling chamber 6a. Then, when the processing residue D2 accumulated in the processing residue duct 4c is accumulated to some extent, the damper 44 is opened and the motor M3 is driven to flow into the inlet 45a of the screw feeder 45 and to the upper outlet 45b. Although it is transported, it is taken out in a state where the temperature is lowered by heat exchange with the refrigerant C flowing through the cooling jacket 46 during this transporting process.

  The exhaust S2 introduced into the cooling chamber 6a is cooled and condensed by heat exchange with the refrigerant C flowing through the cooling pipe 62. In the processing method of the present invention, the object to be processed that supplies this cooling temperature to the rotary kiln 1 is used. By setting the temperature to be equal to or lower than the temperature of D1, all the extracted components contained in the water vapor that is the main component of the exhaust gas are condensed or liquefied and brought into the condensed water.

  That is, when the above cooling temperature is higher than the temperature of the workpiece D1 supplied to the rotary kiln 1, the workpiece D1 is vaporized in the process of raising the temperature from the original temperature to the temperature corresponding to the cooling temperature in the rotary kiln 1. The extracted component remains as a gas without being condensed in the cooling chamber 6a. However, if the cooling temperature is equal to or lower than the temperature of the original workpiece D1, the extracted component is present in the workpiece D1 before processing. It returns to the state of being contained without being vaporized, that is, liquid or solid.

  In this way, in this treatment method, the entire amount of the low boiling point substance extracted from the workpiece D1 can be recovered together with the condensed water, so that an advanced exhaust gas treatment as in the conventional heat treatment is unnecessary, and thus the entire treatment facility is small. In addition to significantly reducing processing costs and equipment costs compared to conventional methods, when pollutants such as contaminated soil are to be treated, the entire system can be closed to restore the pollutants to the environment. Spattering can be reliably prevented. Furthermore, according to this processing method, the extracted components are not oxidized by high-temperature air, so that subsequent processing is easy, and since there is no oxidative change, it is easy to recycle contaminants such as mercury and low-boiling organic substances. become. Further, the treatment residue D2 is not deteriorated due to oxidation, and contaminants such as contaminated soil return to a state close to that before the contamination, so that there is no hindrance to reuse, and in addition, moisture contained in the object to be treated D1 Since it is vaporized and removed along with the exhaust S2 and taken out as a dry state, handling such as transportation and storage becomes easy, and there is an advantage that drying as a pretreatment can be omitted at the time of reuse.

  Thus, during the extraction process, the valve V2 of the exhaust pipe 9a in the cooling device 6 is closed and the valve V1 of the exhaust pipe 63 is opened, but its outlet is sealed with water, so that the cooling chamber 6a is exhausted. Only the filter chamber 4b of the exhaust separation tank 4 communicates with the inlet pipe 61. As a result, a negative pressure is generated in the cooling chamber 6a due to a decrease in volume accompanying the condensation of the exhaust S2, and this negative pressure acts as a suction force that draws the exhaust S2 into the cooling chamber 6a. It functions as power to be introduced into the processing space 10. Therefore, in this configuration, mechanical equipment such as a fan for forcibly supplying and discharging the superheated steam S1 and the exhaust gas S2 can be omitted, and the negative pressure acting on the processing space 10 in the rotary kiln 1 can be used in the workpiece D1. Since the vaporization of the extracted components is promoted, the extraction efficiency is further improved, and the pressure inside the rotary kiln 1 communicates with the cooling chamber 6a of the cooling device 6 so that the pressure in the entire processing space is in an equilibrium state. The extraction speed can be easily controlled by the supply temperature and the cooling temperature, and this eliminates the need for a complicated control mechanism, and the entire processing space is in a non-pressurized state and does not require large pressure resistance on the vessel wall. The processing device can be designed simply and safely.

  The condensed water W2 generated in the cooling chamber 6a flows into the overflow tank T1 in a state containing liquefied or solidified extract components, and high specific gravity substances such as mercury Hg in the extract components are accumulated at the bottom of the tank T1. After the treatment, the drain valve V3 of the tank T1 can be opened to extract and collect mercury Hg and the like. On the other hand, the condensed water W2 containing the low-specific gravity extraction component overflows from the overflow tank T1 and is stored in the condensate recovery tank T2. Therefore, if the drain valve V4 is opened after being processed or at a stage where the liquid amount reaches a predetermined level, the water is extracted. Good.

  Note that in the process, gas components generated by thermal decomposition of air or organic substances in the workpiece D1 accompany the exhaust S2, and these non-condensed gas components gradually accumulate in the cooling chamber 6a of the cooling device 6. However, since the amount of non-condensable gas components generated per unit amount of the workpiece D1 is small, it is possible to continuously process a large amount of the workpiece D1 until the cooling efficiency is reduced due to the accumulation. It is. For such a non-condensable gas component, a continuous treatment amount is determined empirically according to the type and properties of the object to be processed D1 (the amount of mixed air, the type and amount of organic matter, etc.). When the processing is completed, the valve V2 of the exhaust pipe 9a is temporarily opened and the fan F of the exhaust pipe 9b is driven to discharge the amount accumulated in the cooling chamber 6a. At this time, even if a trace amount of harmful substances is mixed in the non-condensed gas component for some reason, it is adsorbed and removed in the process of passing through the activated carbon filling tank 7, and thus released into the atmosphere as a harmless purified gas G mainly composed of air. Is done.

  In the above-described embodiment, the superheated steam S1 is discharged from the peripheral portion and the central portion into the processing space 10 of the rotary kiln 1, but the extraction processing method of the present invention uses the superheated steam S1 continuously supplied from the outside. Various methods for vaporizing and extracting low-boiling substances by filling the space 10 are included. For example, the superheated steam supply line 20 of the stirring shaft 2 may not be provided, and the processing space 10 may be filled only by releasing the superheated steam S1 introduced between the inner and outer cylinders 11 and 12 of the rotary kiln 1 from the peripheral portion. . On the other hand, the inner cylinder 11 of the rotary kiln 1 is not provided with the air holes 14... And the heated air is circulated between the inner cylinder 11 and the outer cylinder 12, so that heating is performed from the surrounding portion by indirect heating. The superheated steam S1 can also be fed into the processing space 10 from the superheated steam supply conduit 20 of the stirring shaft 2 or the inlet 1a side of the rotary kiln 1. However, in the comparison of the method in which the superheated steam S1 is released from only one of the peripheral part and the central part of the processing space 10, the extraction efficiency from the peripheral part is higher. Therefore, by adopting a system in which the superheated steam S1 is supplied from both the peripheral portion and the central portion into the processing space 10, it becomes easy to set the entire processing space 10 to an optimum atmosphere for extracting contaminants. .

  In the above-described embodiment, the superheated steam supply pipe 20 that discharges the superheated steam S1 from the center to the processing space 10 also serves as the stirring shaft 2, but the supply pipe 20 has a simple pipe shape without a stirring function. As an alternative, the superheated steam S1 may be discharged from the whole or a major portion of the vent holes 22. Alternatively, the agitator shaft 2 may be used instead of the stirring blade 21. It is good also as a structure provided in both the surrounding surface of itself, and this stirring shaft 2 and the stirring blade 21. Furthermore, in the structure which discharge | releases the superheated steam S1 to the process space 10 from a peripheral part and a center part, the superheated steam supply amount from a peripheral part is increased on the inlet 1a side rather than the outlet 1b side of the rotary kiln 1, and from the center part. As a means for setting the superheated steam supply amount to be larger at the outlet 1b than at the inlet 1a side, the hole diameters of the vent holes 14 and 22 are changed in the above-described embodiment. Instead of this, the density of the two air holes 14... 21 may be changed, or this density change and hole diameter change may be combined.

  In the embodiment, the rotary kiln 1 has been described as having the outlet 1b side disposed at a low slope. However, the spiral fin having a function of transferring the workpiece D1 to the outlet side as it rotates on the inner peripheral surface of the inner cylinder 11. In addition, by providing an annular inclined plate or the like arranged at regular intervals, processing in a horizontal posture is also possible. Further, the outer cylinder 12 can be integrated with the inner cylinder 11 without non-rotating, and even in this case, the superheated steam S1 is supplied to the annular space 15 between the inner and outer cylinders 11 and 12 on the center side of the end. This can be achieved by an appropriate internal flow path configuration from the supply port. Further, in the configuration in which the heated steam is discharged only from the peripheral portion of the processing space, the rotary kiln 1 is inclined and the stirring shaft 2 is omitted, or the spiral fin or the annular inclined plate is provided on the inner cylinder 11 side instead of the stirring shaft 2. Or you may provide the protrusion etc. which have another stirring function.

  The extraction processing method of the present invention is not limited to extraction processing of contaminating components such as contaminated soil, but can be widely applied to various extraction processing in manufacturing industrial raw materials and intermediate raw materials. In addition, since the processing apparatus to which this extraction processing method is applied can be easily downsized as described above, the entire processing apparatus can be mounted on a moving vehicle, and the processing apparatus can be brought into the contaminated area for on-site processing. It becomes possible.

It is a schematic block diagram of the processing apparatus to which the extraction processing method which concerns on one Embodiment of this invention is applied. It is a side view of the processing apparatus. It is a vertical side view of the rotary kiln part of the processing apparatus. It is a cross-sectional arrow view of the AA line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary kiln 1a Inlet 1b Outlet 10 Processing space 11 Inner cylinder 12 Outer cylinder 14 Ventilation hole 15 Annular space (between inner and outer cylinders)
20 Superheated steam supply line 21 Ventilation hole 6 Cooling device 6a Cooling chamber C Refrigerant D1 Processed object D2 Process residue S1 Superheated steam S2 Exhaust W2 Condensate

Claims (6)

  The object to be treated containing low-boiling substances is continuously fed into the rotary kiln and conveyed to the outlet side, and the inside of the rotary kiln is filled with heated superheated steam continuously supplied from the outside and heated. The boiling point substance is extracted to the gas phase side, and the processed material after extraction is continuously taken out, while the exhaust from the rotary kiln is extracted by cooling to the temperature of the processed material supplied to the rotary kiln and condensing it. An extraction method characterized in that a low boiling point substance is taken into the condensate.   The extraction processing method according to claim 1, wherein a negative pressure generated as the exhaust gas condenses is used as power for introducing superheated steam into the rotary kiln.   The rotary kiln has a double cylinder structure of an inner cylinder and an outer cylinder having a porous structure, and superheated steam introduced between the inner and outer cylinders is supplied into the processing space of the rotary kiln through a hole in the inner cylinder. Extraction processing method.   By providing a superheated steam supply pipe disposed along the axis in the processing space of the rotary kiln having a double cylinder structure, by introducing superheated steam between the superheated steam supply pipe and the inner and outer cylinders, While supplying superheated steam from both the peripheral part and the central part in the processing space, the superheated steam supply amount from the peripheral part is larger on the inlet side than the rotary kiln outlet side, and the superheated steam supply amount from the central part is on the rotary kiln inlet The extraction processing method according to claim 3, wherein the extraction processing method is set so as to be larger on the exit side than on the side.   The extraction processing method according to any one of claims 1 to 4, wherein the object to be processed is a contaminant due to mercury or / and a low boiling point organic substance.   The extraction processing method according to any one of claims 1 to 5, wherein the temperature in the rotary kiln is set to 110 to 350 ° C.

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