JP2011121032A - Sorting apparatus, sorting method, and soil purification equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately sort soil and heavy metals. <P>SOLUTION: This sorting apparatus is constituted so as to sort heavy metals from heavy metal-containing soil by utilizing sedimentation rate difference and includes a water tank 1, a bed screen 2 provided so as to be immersed in the water of the water tank 1, a bed 5 provided so as to be immersed in the water of the water tank 1, formed so that bed particles having a particle size larger than the mesh size of the bed screen 2 are provided on the bed screen 2 in a layered state and receiving the supply of the heavy metal-containing soil 6 on the upper side thereof, a water supply valve 8 for supplying water to the water thank 1, a separated soil discharge port 14 for discharging the water in the water tank 1 and the soil on the bed 5 and a diaphragm 10 for shaking the bed 5 on the soil 6 on the bed 5. The bed 5 is constituted of the bed particles having a specific gravity between the specific gravities of both of the particles of the soil 6 and the particles of the heavy metals and higher than the particles of the soil 6 and lower than the particles of the heavy metals with respect to a sedimentation rate prescribed by specific gravity and a particle size. The heavy metals in the soil 6 are sorted by passing the soil 6 through the bed 5 and the bed screen 2 to sediment the heavy metals in the water tank 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sorting apparatus, a sorting method, and a soil purification facility that sort heavy metals from soil contaminated with heavy metals such as lead, cadmium, and chromium by using a sedimentation speed difference.

Due to recent industrial activities, contamination of soil and groundwater due to oil, organic solvents, heavy metals, etc. in urban areas and factory sites has become apparent, which has become a social problem that has hindered the use of land and groundwater.
At present, various purification measures are being taken against such pollution, and in particular, as a countermeasure for heavy metal-contaminated soil, a method using insolubilization treatment has been frequently used. However, when reusing land using this kind of method, in which heavy metals remain on the raw soil, it is subject to restrictions due to legal revisions, and in order to reuse land without any restrictions in the future, It is required to separate and remove heavy metals from contaminated soil.

As a technique for separating heavy metals from contaminated soil in this way, there is known a technique for separating heavy metals from contaminated soil using the difference in sedimentation speed between soil and heavy metals as described in Patent Documents 1 and 2. .
In Patent Document 1, a screen plate is disposed in a water tank, and an upper portion thereof is used as a separation chamber for separating heavy metal from the contaminated soil to be introduced, and an air chamber is provided below the screen plate. Describes an apparatus that swings water on a screen plate and contaminated soil by sending and exhausting air, and separates the soil and heavy metal into layers by a difference in sedimentation speed due to a difference in specific gravity.
Further, in Patent Document 2, a liquid containing lead and sand flows into a lead separation tank to generate an upward flow, and the upward flow rising speed is smaller than the lead sedimentation speed and equal to or higher than the sand sedimentation speed. A device is described that separates both by utilizing the difference in sedimentation velocity caused by the difference in specific gravity between lead and sand.

JP 2003-39060 A JP 2004-216204 A

By the way, by using the technology to separate soil and heavy metals using the difference in sedimentation rate, it is possible to save energy and eliminate the need for measures against environmental pollution caused by dusting, which is essential in dry processing. Is obtained.
However, the sedimentation rate of solids in the fluid tends to be fast when the particle size of the solids is large and slow when the particle size is small. In the devices of Patent Documents 1 and 2 that use only the specific gravity difference, it is difficult to accurately select soil and heavy metals.
That is, in the apparatus of Patent Document 1, a heavy metal having a small particle size with a slow sedimentation rate is deposited on the upper layer of the soil, the boundary between the soil and the heavy metal becomes ambiguous, and there is a possibility that the separated products are mixed with each other. Moreover, in the apparatus of patent document 2, if it is going to discharge | emit large particle | grains of soil to upper part, lead with small particle size will be discharged | emitted together and there exists a possibility that lead may mix in clean soil.
Therefore, there is a need for a technique that can accurately select soil and heavy metal while utilizing the difference in sedimentation speed between soil and heavy metal.

  The present invention is proposed in view of the above-described problems, and has advantages such as energy saving treatment, no need for countermeasures against environmental pollution due to dust generation, and in addition, using the difference in sedimentation speed between the soil and It is an object of the present invention to provide a sorting device, a sorting method, and a soil purification facility that can accurately sort heavy metals.

The sorting device of the present invention is a sorting device that sorts heavy metals from soil containing heavy metals using a difference in sedimentation speed, a fluid tank, and a bed screen provided to be immersed in the fluid of the fluid tank, Beds that are immersed in the fluid of the fluid tank, and bed particles having a particle size larger than the mesh of the bed screen are provided in layers on the bed screen, and soil containing heavy metal is supplied to the upper side. A fluid supply section for supplying fluid to the fluid tank; a discharge port for discharging the fluid in the fluid tank and the soil on the bed; and a swinging section for swinging the soil on the bed and the bed. A bed particle having a specific gravity intermediate between the particles of the soil and the particles of the heavy metal, and having a sedimentation rate defined by the specific gravity and the particle size that is faster than the particles of the soil and slower than the particles of the heavy metal. Configure the serial bed, characterized by sorting by precipitating the heavy metal of the soil to the bed and the fluid tank is passed through the bed screen. The fluid is appropriate within the scope of the present invention, such as water.
In the above configuration, by providing bed particles that are faster than the soil particles and slower than the heavy metal particles with respect to the sedimentation rate defined by the specific gravity and the particle size, it is possible to accurately select the soil and the heavy metal using the difference in the sedimentation rate. In addition, the bed of bed particles can clearly separate soil and heavy metal regardless of the amount of solid heavy metal in the soil, thereby preventing mutual contamination. Therefore, soil and heavy metal can be accurately selected in the selection of soil and heavy metal using soil and heavy metal, which can be processed with energy saving and have no advantage of environmental pollution countermeasures due to dust generation. Further, since the bed particles have an intermediate specific gravity between the soil particles and the heavy metal particles, the bed particles can be more stably provided in layers on the bed screen.

The sorting apparatus of the present invention is characterized in that the bed particles are spherical particles.
By the said structure, a heavy metal can be settled more smoothly and a heavy metal can be more correctly selected.

Further, the sorting device of the present invention is configured to flow the fluid from the lower side to the upper side of the bed screen and swing the bed and the soil by applying vibration to the fluid. It is characterized by doing.
With the above-described configuration, for example, the bed and the soil thereon can be swung using a water flow without using a mechanism for vibrating the bed screen.

The screening apparatus according to the present invention includes an openable / closable gate provided in the vicinity of the bed screen and in the vicinity of the discharge port, and a sight glass or residual metal detection provided in the vicinity of the bed screen and in the vicinity of the gate. And when the heavy metal staying on the bed screen reaches a predetermined amount by visual inspection from the sight glass or detection by the residual metal detection part, the gate is opened and discharged to stay. A heavy metal is allowed to settle in the fluid tank.
For example, when the heavy metal mixed in the soil is deformed and stays on the bed screen without being discharged under the bed screen, the mesh of the bed screen and the bed particles, soil particles, heavy metal particles When heavy metal stays on the bed screen, such as when the heavy metal stays on the bed screen, such as when the alignment is not sufficient and the small particle size range stays on the bed screen, the staying heavy metal is discharged into the fluid tank through the gate. It is possible to prevent heavy metals from being deposited on the screen.

The sorting method of the present invention is a sorting method for sorting heavy metals from soil containing heavy metals using the difference in sedimentation speed, and has a particle size larger than the mesh of the bed screen and has a specific gravity in the fluid of the fluid tank. A first step of supplying soil containing heavy metal on a bed in which bed particles that are faster than the particles of the soil and slower than the particles of the heavy metal are provided in layers on the bed screen with respect to the sedimentation rate defined by the particle size A fluid is supplied to the fluid tank and the bed and the soil are swung so that the heavy metal in the soil passes through the bed and the bed screen and settles in the fluid tank, and the flow of the fluid And a second step of discharging the soil on the bed.
In the above configuration, by providing bed particles that are faster than the soil particles and slower than the heavy metal particles with respect to the sedimentation rate defined by the specific gravity and the particle size, it is possible to accurately select the soil and the heavy metal using the difference in the sedimentation rate. Moreover, regardless of the amount of solid heavy metals in the soil, the bed and particles can clearly separate the soil and heavy metals and prevent mutual contamination. Therefore, soil and heavy metal can be accurately selected in the selection of soil and heavy metal using soil and heavy metal, which can be processed with energy saving and have no advantage of environmental pollution countermeasures due to dust generation.

In the second method, in the second step, the fluid is caused to flow from the lower side to the upper side of the bed screen, and the bed and the soil are shaken by applying vibration to the fluid. Features.
With the above-described configuration, for example, the bed and the soil thereon can be swung using a water flow without using a mechanism for vibrating the bed screen.

Moreover, the soil purification equipment of the present invention classifies soil containing heavy metals into coarse grains, medium grains, and fine grains in a first classifying section such as a two-stage wet vibrating sieve, and according to the present invention for the medium grains. The heavy metal is sorted using a sorting apparatus for medium grains, and the fine grain sorting apparatus according to the present invention is used for the fine grains obtained by further classifying the fine grains with a second classification section such as a wet vibration sieve. And selecting heavy metals.
In the above-described configuration, by providing a classification unit in which the particle size range to be classified and the sedimentation speed are matched in advance with the sorting device in the previous process of the sorting device, the sorting amount in the sorting process can be reduced and the sorting efficiency by the plants can be reduced. And improve the efficiency of the sorting device and soil purification equipment.

  According to the present invention, the soil and heavy metal can be accurately selected in the selection of soil and heavy metal using the difference in sedimentation speed between the soil and heavy metal, which has advantages such as energy saving treatment and no need for countermeasures against environmental pollution due to dust generation. Can do.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a longitudinal front view showing a configuration of a sorting device according to an embodiment of the present invention. The longitudinal section side view showing the composition of the sorting device of the embodiment by the present invention. The flowchart which shows the purification process process of a soil purification facility provided with the screening device of embodiment. The schematic diagram which shows typically the relationship between the particle size of a bed particle, and the particle size of a soil particle. The partial schematic diagram which shows typically the relationship between the particle size of a bed particle and the particle size of a soil particle.

[Sorting Device of Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal front view showing the configuration of the sorting apparatus of the embodiment, and FIG. 2 is a longitudinal side view showing the configuration of the sorting apparatus of the embodiment.

  The sorting apparatus according to the present embodiment sorts heavy metals from soil containing heavy metals using a difference in sedimentation speed, and as shown in FIGS. 1 and 2, the lower part thereof has a weight shape such as a substantially conical shape. There is a water tank 1 which is a fluid tank in which sorting water is stored. A bed screen 2 having a large number of meshes is arranged substantially horizontally on the protruding portion 1a protruding upward in the water tank 1, and is immersed in water separated from the water surface 3 of the water stored in the protruding portion 1a. ing. The upper side of the bed screen 2 is a sorting chamber 4 for sorting soil and heavy metals, and the mesh opening of the bed screen 2 is set larger than the maximum particle size of heavy metals in the six layers of soil. On the bed screen 2, bed particles having a diameter larger than the mesh opening of the bed screen 2 are laid in layers, and are immersed in water separated from the water surface 3 to form five beds. On the bed 5 layer, the contaminated soil 6 containing heavy metal is supplied from the contaminated soil supply port 7 located on the upper left side of FIG. 2 and provided in the water separated from the water surface 3.

  Here, the bed particles constituting the bed 5 will be described in detail. The bed particles have a particle diameter larger than the mesh of the bed screen 2 described above and an intermediate specific gravity between soil particles and heavy metal particles. In order to satisfy the condition that the sedimentation rate is larger than the soil particles and smaller than the heavy metal particles, it is preferable to use spherical particles.

Regarding the sedimentation velocity of the particles under the above conditions, Re: Reynolds number, μ: fluid viscosity coefficient (Pa · s), V: sedimentation velocity (terminal velocity m / s), D: particle size (m), ρf: fluid density ( kg / m3), ρs: particle density (kg / m3), CR: resistance coefficient, Reynolds number Re is expressed by the following formula (1).
Re = VDρf / μ (1)
The resistance coefficient is represented by the following formulas (2) and (3), the sedimentation speed is represented by the following formula (4), and the conditions for the sedimentation speed of the bed particles satisfy the following formula (4).
CR = 24 / Re Re <1 (2)
CR = (0.55 + 4.8 / √Re) 1 <Re <104 (3)
V = (4 gD (ρs−ρf) / 3ρfCR) 1/2 (4)

  For example, if the heavy metal is lead, the bed particles are aluminum spheres or alumina spheres, and the fluid is water, the specifications are as follows: water particle density: ρf = 1000, water fluid viscosity coefficient: μ = 0.001, soil particle density: ρs = 2600, lead particle density: ρs = 1300, aluminum particle density: ρs = 2700, alumina particle density: ρs = 3600. The actual settling velocity is slower than the calculated value due to the fluctuation of the particles in the fluid and the coarse density between the particles at rest. Table 1 shows the settling velocity calculated for each single particle size by equation (4). become that way. According to Table 1 below, it is possible to use bed particles having a required particle size.

4 and 5 schematically show the relationship between the particle size of the bed particles and the particle size of the soil particles. The large-diameter circle represents the bed particle 5a and the small-diameter circle represents the soil particle 6a. .
FIG. 4 shows a state in which the bed particles 5a and the soil particles 6a that have risen due to the water flow descend due to the difference in sedimentation speed, and the heavy metal particles that are heavier than the bed particles 5a and have a fast sedimentation speed are held between the bed particles 5a. The particles move to the lower portion every time the bed 5 and the soil 6 are swung by the intermittent water flow, and are finally discharged from the bed screen 2 to the hatch.
FIG. 5 shows a relational expression between the particle diameter of the soil particle 6a and the particle diameter of the bed particle 5a. The particle diameter (radius) r of the soil particle 6a is 0.15 times the particle diameter (radius) r0 of the bed particle 5a. However, in the actual apparatus, the bed pressure of the bed 5 is appropriately selected and set to about 0.3 times.

  In the sorting apparatus, the water tank 1 is provided with a water supply valve 8 that is a fluid supply unit, and the water supply is supplied into the water tank 1 through the water supply valve 8 constantly or intermittently. Further, a diaphragm 10 that is a swinging portion is provided at a place other than the place where the protruding portion 1 a of the water tank 1 is provided so that the drive shaft 9 can be moved up and down. When the diaphragm 10 is reciprocated through the drive shaft 9 by a drive source (not shown), the water in the water tank 1 that is subjected to vibration by being in contact with the diaphragm 10 is swung in the direction indicated by the two-dot chain line in the figure. The moving water swings the bed 5 and the soil 6 through the mesh of the bed screen 2 of the sorting chamber 4.

  A drain valve 12 is provided at the bottom of the water tank 1 to discharge the separated heavy metal 11 deposited on the bottom to the outside of the apparatus, and in the vicinity of the lower end of the water tank 1, the amount of heavy metal deposited on the lower end of the water tank 1 is constant. A detector 13 is provided for detecting the occurrence of the failure.

  In the upper right side of FIG. 2, a separated soil discharge port 14 for discharging clean soil together with water from the aquarium 1 is formed. The separated soil discharge port 14 corresponds to the height of the layered soil 6 or the layered soil 6. It is formed in the height corresponding to the upper part of. Reference numeral 16 denotes a separated soil discharge path for further conveying and discharging the soil 6 discharged from the separated soil discharge port. In addition, a gate that can be opened and closed for discharging heavy metal remaining on the bed screen 2 into the aquarium 1 is disposed below the separated soil outlet 14 in the vicinity of the bed screen 2 and in the vicinity of the separated soil outlet 14. 15 is provided. In the opening and closing of the gate 15, a sight glass 17 for visually observing the state on the bed screen 2 is provided near the bed screen 2 in the vicinity of the bed screen 2, and the gate 15 is opened and closed according to the observation result by the sight glass 17. Alternatively, a residual metal detector 18 that detects heavy metal remaining in the vicinity of the gate 15 and the bed screen 2 is provided, and the gate 12 is opened and closed in conjunction with the detection result of the residual metal detector 18.

  The operation of the sorting apparatus of this embodiment will be described. First, soil 6 contaminated with heavy metals such as soil contaminated with lead shot is supplied from the contaminated soil supply port 7 to the bed 5 in the sorting chamber 4 by the contaminated soil supply means (not shown). On the other hand, the water supply valve 8 is continuously or intermittently opened by the control of a control unit that operates according to a control program (not shown), and water is continuously or intermittently supplied into the water tank 1. 10 is reciprocated to add vibration, and thereby the water in the water tank 1 is swung in the direction of the arrow of the thick two-dot chain line shown in the figure. This rocking of the water rocks the bed 5 and the soil 6 above it through the mesh of the bed screen 2 of the sorting chamber 4. Further, the supplied water flows from the lower side to the upper side of the bed screen 2 and flows so as to overflow from the separated soil discharge port 14, and the supplied soil 6 is left-hand side of FIG. From the contaminated soil supply port 7 toward the separated soil discharge port 14 on the right side of FIG.

  When the water is continuously swung while supplying water, the heavy metal in the soil 6 gradually moves along with the soil 6 to the separated soil discharge port 14 and descends in the soil 6 due to the difference in sedimentation speed between the soil particles and the heavy metal particles. It reaches the bed 5 and descends through the bed particles, passes through the bed 5 and reaches the bed screen 2. Since the mesh of the screen of the bed screen 2 is set larger than the maximum particle size of heavy metal in the soil 6, the heavy metal passes through the bed screen 2 and settles in the water tank 1 and is separated into the bottom of the water tank 1. Deposited as heavy metal 11. In addition, the soil 6 from which the heavy metal has been separated moves on the bed 4 and is discharged together with the overflowing water from the separated soil discharge path 16 through the separated soil discharge port 14.

  The detector 13 detects the amount of the separated heavy metal 11 deposited on the bottom of the water tank 1 continuously or intermittently, and the detected value is output to a control unit that operates according to a control program (not shown). The control unit compares the reference value set in the storage unit with the detection value acquired from the detection unit 13 as needed, and supplies the contaminated soil when the detection value reaches a set reference value that is a predetermined amount. The means is temporarily stopped to stop the supply of the contaminated soil 6, the water supply of the water supply valve 8 and the operation of the diaphragm 10 are stopped, the discharge valve 12 is opened, and the deposited separated heavy metal 11 is discharged out of the apparatus. After the separated heavy metal 11 is discharged, the control unit operates the contaminated soil supply unit, the water supply valve 8 and the diaphragm 10 again, and restarts the heavy metal selection process from the soil 6. For the detector 13, for example, an appropriate detector capable of detecting heavy metals such as a fluorescent X-ray detector that measures X-ray fluorescence by irradiating X-rays can be used.

  Further, residual heavy metal that has not passed through the bed screen 2 due to deformation or the like moves on the bed screen 2 toward the separated soil discharge port 14 or the gate 15. For the remaining heavy metal, the heavy metal on the bed screen 2 is visually observed with the sight glass 17, and the gate 15 is opened as necessary to discharge the remaining heavy metal into the water tank 1, or on the bed screen 2. In conjunction with the detection of heavy metal by the residual metal detector 18, the gate 15 is opened to discharge the remaining heavy metal into the water tank 1 so that the heavy metal is not retained on the bed screen 2.

  For the interlocking of the residual metal detector 18 and the gate 15, the same or the same type of configuration as that of the control unit of the detector 13 can be used. For example, a control unit that operates according to a control program (not shown) stores its memory. The reference value set in the unit is compared with the detection value acquired from the residual detection unit 18 as needed, and when the detection value reaches the set reference value that is a predetermined amount, the gate 15 is opened and the bed screen 2 is opened. The heavy metal remaining in the water tank 1 is discharged into the water tank 1. Further, the gate 15 can be opened and closed at an appropriate point in time when the sorting device is in operation.

  Next, the example which provides the sorting apparatus of this embodiment in soil purification equipment is demonstrated. Drawing 3 is a flow chart which shows the purification processing process of a soil purification facility provided with the sorting device of an embodiment.

  3 includes a receiving hopper 101, a cutting feeder 102, a drum washer 103, a two-stage wet vibrating screen 104, a medium grain sorting device 105, a wet vibrating screen 106, a dehydrating device 107, and a dehydrating device. The apparatus 108, the water treatment device 109, the fine particle sorting device 110, the fine particle sorting device 111, the classification device 112, and the dehydrating device 113 are provided. Two sorters 110 are provided.

In this soil purification facility, contaminated soil to be input to the receiving hopper 101 is temporarily stored, and the contaminated soil is cut out and supplied by the cutting feeder 102. The drum washer 103 injects cleaning water into the supplied contaminated soil, and stirs to crush and knead the contaminated soil, and separates and cleans heavy metal and soil.
The two-stage wet vibrating screen 104 corresponding to the first classification unit classifies the contaminated soil into coarse particles, medium particles, and fine particles while spraying cleaning water on the contaminated soil charged from the drum washer 103, Next, the middle and fine grains are classified into a middle grain and a fine grain, respectively, and classified in two stages. In this example, the mesh size of the upper sieve of the two-stage wet vibrating sieve 104 is 10 mm, and the mesh of the lower sieve. The size of the soil is classified as 2.2 mm, and the soil is classified into coarse particles having a particle size of 10 mm or more, medium particles having a particle size of 2.2 mm or more and less than 10 mm, and fine particles having a particle size of less than 2.2 mm. Here, those classified into coarse particles on the upper sieve are collected.

What is classified into medium grains on the lower sieve by the two-stage wet vibrating sieve 104 is sent to the intermediate grain sorting device 105. The medium grain sorting device 105 sorts the medium grain soil and heavy metals using the difference in sedimentation speed, and the medium grain heavy metals sorted here are sent to the dehydrator 107 to be dehydrated and collected.
Further, the medium-sized soil sorted by the medium-grain sorting device 105 is sent to the dehydrating device 108 to be dehydrated and collected. Water generated in the dehydrator 108 is sent to the water treatment device 109 where it is treated and drained.

  In the intermediate particle sorting apparatus 105 in this example, aluminum particles having a particle diameter of 10 mm are used as bed particles of the bed 5, the mesh of the bed screen 2 is 9 mm, and the bed screen 2 swings while supplying water from the water supply valve 8. In this case, from Table 1, lead, which is a heavy metal of 2.2 mm ≦ D (particle size) <10 mm, has a higher settling speed than aluminum particles of 10 mm particle size, which are bed particles, as shown in Table 1. Lead gradually settles under the bed 5, and lead having a particle size smaller than 9 mm passes through the bed screen 2 and settles on the bottom of the water tank 1. At this time, if lead of 9 mm ≦ D (particle diameter) <10 mm is present, it moves on the bed screen 2 to the gate 15 side as it swings, and a predetermined amount of staying or residual metal detection unit by the sight glass 17 When a predetermined amount is detected by 18, the gate 15 is opened, discharged into the water tank 1, and settled at the bottom of the water tank 1. In addition, the soil of 2.2 mm ≦ D (particle diameter) <10 mm in the sorting chamber 4 has a lower sedimentation speed than the aluminum particles having a particle diameter of 10 mm, which are bed particles, as shown in Table 1. When the soil 6 is supplied and rocked, the soil 6 gradually moves to the right side in FIG. 2 and is discharged from the separated soil discharge port 14.

  Further, the fine particles classified by the two-stage wet vibrating screen 104 are further sent to the wet vibrating screen 106 corresponding to the second classifying section, and are classified into fine particles and fine particles by the wet vibrating screen 106. In this example, the mesh size of the sieve of the wet vibrating sieve 106 is 0.6 mm, and the particle diameter of 0.6 mm or more and less than 2.2 mm that passes through the two-stage wet vibrating sieve 104 and remains on the sieve of the wet vibrating sieve 106. The one having a particle diameter of less than 0.6 mm that has passed through the two-stage wet vibration 104 and the wet vibration sieve 106 is classified into fine particles. Fine particles of 0.6 mm ≦ D (particle size) <2.2 mm classified by the wet vibrating screen 106 are sent to the fine particle sorting device 110, which uses the difference in sedimentation speed to finely fine the particles. Grain soil and heavy metals are sorted, and the fine heavy metals sorted here are recovered. Further, the fine soil selected by the fine particle sorting device 110 is sent to the classification device 112 together with the fine soil selected by the fine particle sorting device 111, which will be described later, and is classified. It is sent to 113 for dehydration and collected as soil. Slurry and water generated in the classification device 112 are sent to the water treatment device 109 for treatment and drainage.

  In the fine particle sorting apparatus 110 in this example, aluminum particles having a particle size of 2.3 mm are used as bed particles of the bed 5, the mesh opening of the bed screen 2 is set to 2 mm, and rocking while supplying water from the water supply valve 8. To do. In this case, from Table 1, lead, which is a heavy metal with 0.6 mm ≦ D (particle size) <2.2 mm, has a higher settling speed than aluminum particles with a particle size of 2.3 mm, which are bed particles. As lead is gradually repeated, lead gradually settles under the bed 5, and lead having a particle diameter of less than 2 mm passes through the bed screen 2 and settles on the bottom of the water tank 1. At this time, if lead of 2 mm ≦ D (particle diameter) <2.2 mm is present, it moves on the bed screen 2 to the gate 15 side as it swings, and a predetermined amount of stagnation or residual metal by the sight glass 17 By detecting a predetermined amount by the detection unit 18, the gate 15 is opened, discharged into the water tank 1, and settled at the bottom of the water tank 1. In addition, the soil of 0.6 mm ≦ D (particle diameter) <2.2 mm in the sorting chamber 4 is deposited on the bed 5 because the settling speed is slower than the aluminum particles having a particle diameter of 10 mm, which is bed particles, as shown in Table 1. When the soil 6 is supplied and rocked while moving, it gradually moves to the right side of FIG. 2 and is discharged from the separated soil outlet 14.

  The fine particles classified under the sieve by the wet vibrating sieve 106 (in this example, fine particles having a particle size of less than 0.6 mm) are put into a fine particle sorting device 111 which is a centrifugal sorting device (not shown) and sorted and sorted. Fine heavy metals are discarded or recovered. In addition, the soil that does not contain heavy metals sorted by the fine grain sorting device 111 is sent to the classification device 112 and classified, and those having a predetermined particle size or more are sent to the dehydration device 113 for dehydration, and recovered as soil. The water used in the classification device 112 is sent to the water treatment device 109 for treatment and drainage. In addition, the water used in the fine particle sorting device 111 is also sent to the water treatment device 109 as it is for treatment and drainage.

  In the above embodiment, by providing bed particles that are faster than the soil particles and slower than the heavy metal particles with respect to the settling velocity defined by the specific gravity and the particle size, it is possible to accurately select the soil and heavy metals using the difference in the sedimentation velocity. . Moreover, the separation boundary of soil and heavy metals can be clarified by the bed 5 of bed particles, and mutual mixing can be prevented. In addition, the bed particles having an intermediate specific gravity can provide bed particles more stably on the bed screen 2 in a layered manner, and a reliable and wide range of particle diameters that can be selected based on the settling speed difference can be secured. In addition, when the bed particles are spherical particles, heavy metals can be settled more smoothly, and heavy metals can be more accurately selected. In addition, the diaphragm can swing the bed and the soil on the bed using water flow. Further, the gate can prevent heavy metal from being deposited on the bed screen. In addition, by providing a classification part in the pre-process of the sorting device in which the particle size range to be classified and the sedimentation speed are matched with the sorting device in advance, the sorting amount in the sorting process is reduced and the sorting efficiency is reduced due to the plants. Thus, it is possible to improve the efficiency of the sorting device and the soil purification facility.

  The invention disclosed in this specification is specified by changing these partial configurations to other configurations disclosed in this specification, in addition to the configurations of each invention and embodiment, to the extent applicable. Also included are those specified by adding other configurations disclosed in this specification to these configurations, or those conceptualized by deleting these partial configurations to the extent that partial effects can be obtained. To do.

  The example which sorts the soil contaminated with the lead shot of the following Table 2 with a sorting device is explained. Table 2 shows the soil of each particle size, the distribution / ratio (particle size distribution) of the soil of each particle size, and the lead content contained in the soil of each particle size. In addition, the bed 5 in the sorting apparatus is formed using an alumina sphere having a particle diameter of 7 mm, the bed screen 2 has an opening of 6 mm, and a soil particle diameter of 2.2 mm ≦ D (particle diameter) < A medium grain sorting device for sorting 10 mm of soil was constructed. As a result of classifying and sorting the contaminated soil into medium grains, the lead contained in the recovered soil of 2.2 mm ≦ D (particle diameter) <10 mm is eluted to less than 150 mg / kg. The amount was less than 0.01 mg / L.

  Further, the bed 5 is formed by using an aluminum sphere having a particle size of 2.3 mm as bed particles in the sorting device, and the opening of the bed screen 2 is selected to be 2 mm, so that the soil particle size is 0.6 mm ≦ D (particle size). <The fine grain sorter which sorts out 2.3 mm soil was constituted. As a result of classifying and sorting the contaminated soil into fine particles in this fine particle sorting apparatus, the lead content in the recovered soil of 0.6 mm ≦ D (particle size) <2.3 mm is less than 150 mg / kg. The elution amount was less than 0.01 mg / L.

  The present invention can be used for purifying soil contaminated with heavy metals such as lead, cadmium, and chromium.

DESCRIPTION OF SYMBOLS 1 ... Water tank 1a ... Protruding part 2 ... Bed screen 3 ... Water surface 4 ... Sorting room 5 ... Bed 5a ... Bed particle 6 ... Soil 6a ... Soil particle 7 ... Contaminated soil supply port 8 ... Water supply valve 9 ... Drive shaft 10 ... Diaphragm 11 ... Separated heavy metal 12 ... Drain valve 13 ... Detector 14 ... Separated soil outlet 15 ... Gate 16 ... Separated soil outlet 17 ... Sight glass 18 ... Residual metal detector 101 ... Accepting hopper 102 ... Cutting feeder 103 ... Drum washer 104 ... 2-stage wet vibrating sieve 105 ... medium grain sorting apparatus 106 ... humidity vibrating sieve 107 ... dehydrating apparatus 108 ... dehydrating apparatus 109 ... water treatment apparatus 110 ... fine grain sorting apparatus 111 ... fine grain sorting apparatus 112 ... classifying apparatus

Claims (7)

A sorting device that sorts heavy metals from a soil containing heavy metals using a settling velocity difference,
A fluid tank;
A bed screen provided to be immersed in the fluid of the fluid tank;
Beds that are immersed in the fluid of the fluid tank, and bed particles having a particle size larger than the mesh of the bed screen are provided in layers on the bed screen, and soil containing heavy metal is supplied to the upper side. ,
A fluid supply section for supplying fluid to the fluid tank;
A discharge port for discharging the fluid in the fluid tank and the soil on the bed;
A rocking portion that rocks the bed and the soil on the bed,
The bed has a specific gravity intermediate between the particles of the soil and the particles of the heavy metal, and the bed is composed of bed particles that are faster than the particles of the soil and slower than the particles of the heavy metal with respect to the sedimentation rate defined by the specific gravity and the particle size. ,
A sorting apparatus for sorting heavy metals in the soil by passing through the bed and the bed screen and settling in the fluid tank.   The sorting apparatus according to claim 1, wherein the bed particles are spherical particles. While flowing the fluid from the bottom to the top of the bed screen,
The sorting apparatus according to claim 1 or 2, wherein the swinging section swings the bed and the soil by applying vibration to the fluid. An openable and closable gate provided in the vicinity of the bed screen and in the vicinity of the outlet;
A sight glass or a residual metal detector provided in the vicinity of the bed screen and in the vicinity of the gate;
When heavy metal staying on the bed screen reaches a predetermined amount by visual inspection from the sight glass or detection of the residual metal detection unit, the gate is opened and discharged,
The sorting apparatus according to claim 1, wherein the stagnant heavy metal is allowed to settle in the fluid tank. A sorting method for sorting heavy metals from soil containing heavy metals using a difference in sedimentation speed,
In the fluid of the fluid tank, bed particles having a particle size larger than the bed screen mesh and a sedimentation rate defined by specific gravity and particle size are faster than the soil particles and slower than the heavy metal particles are layered on the bed screen. A first step of supplying a heavy metal-containing soil on a bed provided in
The fluid is supplied to the fluid tank and the bed and the soil are swung so that the heavy metal in the soil passes through the bed and the bed screen and settles in the fluid tank. A second step of draining the soil on the bed;
A sorting method comprising:   6. The sorting according to claim 5, wherein, in the second step, the fluid is caused to flow from the lower side to the upper side of the bed screen, and the bed and the soil are shaken by applying vibration to the fluid. Method. The soil containing heavy metals is classified into coarse grains, medium grains and fine grains in the first classification section,
Sorting heavy metals using the medium grain sorting device according to any one of claims 1 to 4 with respect to the medium grain,
A soil remediation facility characterized in that heavy metals are sorted using the fine grain sorting apparatus according to any one of claims 1 to 4 with respect to the fine grains obtained by further classifying the fine grains with a second classification section. .

Images