JP6252818B1 - Soil purification system and soil purification method - Google Patents

Abstract

In a soil purification facility for purifying contaminated soil using a chelating agent, means for reducing the amount of chelating agent held and used, and reducing the site area of the facility for recovering the chelating agent I will provide a. A soil purification system includes a soil classification unit that classifies contaminated soil into gravel, sand, and soil, and a sand / soil purification unit 2 that purifies the separated sand and soil with a chelate cleaning solution. The sand / soil purification unit 2 includes a sand cleaning unit 14, a soil cleaning unit 15, a chelating agent regeneration unit 16, a sand rinsing unit 17, a soil rinsing unit 18, and a chelating agent recovery unit 19. The sand cleaning unit 14 and the soil cleaning unit 15 clean the sand and soil with a chelate cleaning solution, respectively. The chelating agent regeneration unit 16 regenerates the chelate cleaning solution and returns it to the sand cleaning unit 14 and the soil cleaning unit 15. The chelating agent recovery unit 19 recovers the chelating agent from the cleaning wastewater discharged from the sand rinsing unit 17 and the soil rinsing unit 18. [Selection] Figure 3

Description

  The present invention classifies soil contaminated with a toxic metal or a compound thereof into a gravel, sand, and soil at a soil classification unit, and the sand and soil separated at the soil classification unit into a chelate cleaning solution containing a chelating agent and water. TECHNICAL FIELD The present invention relates to a soil purification system and a soil purification method that purify using water.

  In recent years, sites of production facilities that use harmful metals such as chromium, lead, cadmium, selenium, mercury and / or their compounds (hereinafter collectively referred to as “hazardous metals”) as raw materials or materials, or the vicinity thereof The problem is soil contamination due to soil contamination or industrial waste disposal including hazardous metals. Then, the soil contaminated with toxic metal (hereinafter referred to as “toxic metal-contaminated soil”) is insolubilized, for example, toxic metal at the position where the toxic metal-contaminated soil actually exists (hereinafter referred to as “original position”). Effective purification, such as by containment or electrical repair, is quite difficult. For this reason, the toxic metal-contaminated soil is generally removed from the original position by excavation or the like and purified by an external soil purification facility.

  As a method for purifying toxic metal-contaminated soil at such off-site soil purification facilities, conventionally, a soil clarification method has been widely used in which toxic metal-contaminated soil is washed with a cleaning solution to remove toxic metals. ing. Thus, the inventor of the present application attaches or binds to soil while wet-classifying the soil contaminated with harmful metals and the like into a gravel, sand, and soil using a chelating cleaning solution containing a chelating agent and water as a cleaning solution. Various types of closed system type soil remediation facilities or soil remediation methods for removing harmful metals and the like that do not discharge the cleaning liquid to the outside have been proposed (see Patent Documents 1 to 14).

Japanese Patent No. 5771342 Japanese Patent No. 5771343 Japanese Patent No. 6022102 Japanese Patent No. 6022103 Japanese Patent No. 6022104 Japanese Patent No. 6026700 Japanese Patent No. 6026701 Japanese Patent No. 6026702 Japanese Patent No. 6052942 Japanese Patent No. 6052943 Japanese Patent No. 6052944 Japanese Patent No. 6052945 Japanese Patent No. 6052946 Japanese Patent No. 6052947

Hideki Kiyosawa “Estimation method of soil surface evaporation based on ground temperature change” Bulletin of Mie University, Mie University Faculty of Agriculture, 1984, 68, 25-40

  By the way, in the soil remediation facilities disclosed in Patent Documents 1 to 14, a cleaning liquid circulating in a series of distribution systems including a mill breaker, a trommel, a cyclone, a thickener, a cleaning liquid storage tank and the like has a predetermined concentration (for example, 0.3 to 1.0 mass%) chelating agent. On the other hand, since a series of distribution systems of soil purification apparatuses hold a large amount of cleaning liquid (for example, 1000 to 2000 tons), a large amount of chelating agent is required to prepare such a cleaning liquid, and the processing cost of soil is low. There is a problem of rising. Furthermore, when it becomes necessary to discard or replace the cleaning liquid in a series of distribution systems for some reason, there is a problem that a large amount of chelating agent contained in the cleaning liquid has to be processed.

  Moreover, although the sand separated in the soil treatment facility is usually reused as a civil engineering / building material, sand containing a chelating agent is not preferable as a civil engineering / building material. On the other hand, the soil separated at the soil treatment facility is reused as, for example, agricultural soil, but soil containing a chelating agent is not preferable as agricultural soil. In addition, the amount of chelating agent in the soil remediation facility decreases by the amount taken away by the sand and soil. It is necessary to replenish the chelating agent. For this reason, in a soil remediation facility that purifies a large amount of contaminated soil (for example, 1000 tons / day), a large amount of chelating agent must be replenished, and the soil treatment cost in the soil remediation facility is very high. There's a problem.

  Therefore, in the soil purification facility described in Patent Documents 3, 6, 9, and 12 according to the present applicant, the sand containing the chelating agent discharged from the hydrocyclone is washed with rinsing water to remove the chelating agent. I have to. On the other hand, washing wastewater containing a chelating agent is evaporated in the atmosphere by the evaporating sand in the sand container, and the chelating agent remains and accumulates in the evaporating sand (so-called salt field method). The chelating agent is recovered by introducing it into the treatment system. However, since a large amount of rinsing water is required to wash the sand containing the chelating agent, there is a problem that a large site is required to install a sand container for evaporating a large amount of washing wastewater. The same problem occurs when the soil separated in the soil purification facility is washed with rinse water.

  The present invention has been made to solve the above-mentioned conventional problems. The soil contaminated with harmful metals is purified using a chelating agent, and the sand and soil are separated from the soil and recycled. In a closed system type soil remediation facility that can be used, the amount of chelating agent retained or distributed in the soil remediation facility can be reduced, and the chelating agent is prevented from being taken out of the soil remediation facility by sand and soil. It is another object of the present invention to provide a means that can be reduced or can reduce the site area of the facility for the recovery of the chelating agent.

A soil purification system for purifying soil that contains gravel, sand, and soil and is contaminated with harmful metals or the like (that is, harmful metals and / or compounds thereof) according to the present invention made to solve the above-described problems, A soil classification unit for classifying into gravel, sand and soil, and a sand / soil purification unit for cleaning and purifying the sand and soil separated by the soil classification unit with a common chelating cleaning solution containing a chelating agent and water It has.

  In this soil treatment system, the soil classification unit includes a mixing device, a trommel, a hydrocyclone, a thickener, and a filter press. Here, the mixing device mixes the soil put into the soil classification unit and the washing water. Trommel separates gravel from a mixture of soil and wash water discharged from the mixing device. The hydrocyclone separates the sand from the mixture of sand, soil and wash water discharged from the trommel. The thickener separates the mixture of soil and washing water discharged from the hydrocyclone into supernatant water and sludge containing soil by sedimentation separation. The filter press separates the soil by filtering sludge discharged from the thickener.

The sand / soil purification unit includes a sand cleaning unit, a soil cleaning unit, a chelating agent regeneration unit, a sand rinsing unit, a soil rinsing unit, and a chelating agent recovery unit. Here, the sand cleaning unit cleans the sand discharged from the liquid cyclone with a chelate cleaning liquid, and removes harmful metals and the like from the sand. The soil cleaning unit cleans the soil discharged from the filter press with a chelate cleaning solution, and removes harmful metals and the like from the soil. The chelating agent regeneration unit is common to the sand cleaning unit and soil cleaning unit, and removes harmful metals from the chelating agent in the chelating cleaning solution discharged from the sand cleaning unit and soil cleaning unit to regenerate the chelating cleaning solution. Return to the sand cleaning section and soil cleaning section. The sand rinsing section removes the chelating agent by washing the sand discharged from the sand washing section with rinsing water. The soil rinsing unit removes the chelating agent by washing the soil discharged from the soil washing unit with rinsing water. The chelating agent recovery unit is common to the sand cleaning unit and the soil cleaning unit, and recovers the chelating agent from the cleaning wastewater containing the chelating agent discharged from the sand rinsing unit and the soil rinsing unit.

  And the sand washing | cleaning part has a flow-type mixing stirrer, a vibration sieve, and a vacuum suction type belt conveyor. The mixing stirrer mixes and stirs the sand discharged from the hydrocyclone and the chelate cleaning solution, and causes the chelating agent to capture harmful metals and the like attached to or bonded to the sand. The vibrating sieve removes (most of) the chelate cleaning solution from the mixture of sand and chelate cleaning solution discharged from the mixing stirrer. The vacuum suction type belt conveyor receives sand wet with the chelate cleaning liquid discharged from the vibration sieve, and while the sand is transported by the filter medium mounting belt, the sand is vacuum sucked through the filter medium mounting belt to chelate the sand. Reduce the cleaning liquid content.

  The soil cleaning unit includes a mixing and dispersing device, a soil cleaning device, and a filtration device. The mixing and dispersing device mixes the soil discharged from the filter press and the chelate cleaning liquid, and generates a soil dispersion slurry in which the soil is dispersed in the chelate cleaning liquid. The soil cleaning device allows the soil dispersion slurry generated by the mixing and dispersing device to flow through a plug flow so as to ensure a preset residence time while stirring, thereby removing harmful metals attached to the soil from the soil. Separated and captured by chelating agent. The filtration device filters the soil dispersion slurry discharged from the soil washing device.

The chelating agent regeneration unit is a solid-phase adsorption that adsorbs harmful metals in the chelating cleaning solution when the chelating cleaning solution discharged from the sand cleaning unit and the filtering device has a higher complexing power than the chelating agent and comes into contact with the chelating cleaning solution. And a chelate cleaning liquid regenerating apparatus that regenerates the chelating cleaning liquid by removing harmful metals from the chelating agent in the chelating cleaning liquid. The sand rinsing unit receives the sand discharged from the sand cleaning unit, and sprays or sprays rinsing water on the sand while transporting the sand with a filter medium mounting belt, thereby removing the chelating agent held in the sand. On the other hand, a vacuum suction type belt conveyor that reduces the amount of rinsing water by evacuating the sand through the filter medium mounting belt and accelerating the downward movement of the rinsing water with the air flowing through the voids between the sand particles Having a sand rinsing device. The soil rinsing unit receives the soil discharged from the soil washing unit, and sprays or sprays rinsing water on the soil while transporting the soil with a filter medium mounting belt to remove the chelating agent held in the soil. On the other hand, a vacuum suction belt conveyor that reduces the amount of rinse water used by vacuum suction of the soil through the filter medium mounting belt and promoting downward movement of the rinse water with air flowing through the voids between the soil particles Having a soil rinsing device.

  The chelating agent recovery unit includes a cleaning wastewater storage tank, a sand container, a roof, a cleaning wastewater spraying device, and a cleaning wastewater reflux mechanism. The washing waste water storage tank receives and stores the washing waste water containing the chelating agent discharged from the sand rinse portion and the soil rinse portion. The sand container is a container having an upper side that is disposed on the ground and accommodates water evaporating sand. A roof is arrange | positioned above a sand accommodating part, and prevents the fall of rain water to a sand accommodating part. The cleaning wastewater spraying device sprays the cleaning wastewater stored in the cleaning wastewater storage tank onto the water evaporation sand stored in the sand storage unit. The washing waste water recirculation mechanism recirculates excess washing waste water flowing down through the gaps between the water evaporation sand particles contained in the sand containing portion to the washing waste water storage tank.

  The soil purification system according to the present invention further includes a water evaporation sand transfer means and a water evaporation sand supply means. Here, the water evaporating sand transfer means is a cleaning wastewater sprayed on the water evaporating sand after the cleaning wastewater is sprayed over a predetermined period from the cleaning wastewater spraying device onto the water evaporating sand accommodated in the sand container. When the water vapor evaporates in the air and the chelating agent is accumulated in the water evaporating sand, the water evaporating sand in which the chelating agent in the sand accommodating portion is accumulated is transferred to the sand washing portion. The water evaporating sand supply means supplies a part of the sand discharged from the sand rinsing unit to the sand accommodating unit as water evaporating sand.

  On the other hand, the soil purification method according to the present invention is used in a soil purification facility or a soil purification system that purifies soil contaminated with harmful metals and the like including gravel, sand, and soil. Here, the soil purification facility or the soil purification system in which the soil purification method according to the present invention is used has substantially the same configuration as the soil purification system according to the present invention (water evaporation sand transfer means and water evaporation sand supply). Except means).

  Thus, in the soil purification method according to the present invention, the washing wastewater sprayed from the washing wastewater spraying device on the water evaporation sand accommodated in the sand container, while the washing wastewater adhering to the water evaporation sand is dispersed. The water is evaporated into the air and removed from the sand container. Then, the water evaporating sand used for a predetermined period of time in the sand container and introducing the chelating agent is introduced into the sand cleaning unit, and the chelating agent accumulated in the water evaporating sand is recovered, while the sand rinsing unit A part of the discharged sand is used as water evaporating sand to be accommodated in the sand accommodating portion. In the soil purification method according to the present invention, fine sand is used as water evaporating sand, and the amount of cleaning wastewater sprayed from the cleaning wastewater spraying device to the sand container is determined by the amount of water evaporating sand stored in the sand container. It is preferable to set so that the water content is maintained at 30 to 35%.

  According to the soil purification system or the soil purification method of the present invention, sand discharged from the liquid cyclone without adding a chelating agent to a large amount of washing water circulating through a series of distribution systems in the soil purification system, and a filter press Since the soil discharged from the soil is washed with the chelate washing liquid, the amount of the chelating agent retained in the soil purification system can be greatly reduced. And since the sand and soil wash | cleaned with the chelate washing | cleaning liquid are wash | cleaned by the rinse water in a sand rinse part and a soil rinse part, respectively, the sand and soil suitable for reuse which do not contain a chelating agent can be obtained. Moreover, since the chelating agent in the washing waste water discharged from the sand rinsing part and the soil rinsing part is returned to the sand washing part by the chelating agent recovery part, the amount of the chelating agent used can be greatly reduced. Furthermore, since the content of the chelate cleaning liquid in the sand wetted with the chelate cleaning liquid is reduced by vacuum suction on the vacuum suction belt conveyor, the amount of rinse water used in the sand rinse section, that is, the amount of cleaning waste water to be evaporated is reduced. And the site area of the sand container in the chelating agent recovery unit can be reduced.

It is a block diagram which shows schematic structure of the soil purification system which concerns on this invention. It is a typical top view which shows schematic structure of the soil classification part which makes a part of soil purification system shown in FIG. It is a block diagram which shows schematic structure of the sand and soil purification part which makes a part of soil purification system shown in FIG. It is a typical elevation view of the sand washing | cleaning part which makes a part of sand / soil purification part shown in FIG. It is a typical elevation which shows the structure of the mixing and dispersing apparatus of the soil washing | cleaning part which makes a part of sand / soil purification part shown in FIG. (A) is a typical top view of the soil washing | cleaning apparatus of the soil washing | cleaning part which makes a part of sand / soil purification part shown in FIG. 3, (b) is a schematic plan of the soil washing | cleaning apparatus shown to (a). It is an AA line sectional view, and (c) is a typical elevation sectional view expanding and showing one slurry channel of a soil washing device. It is a typical elevation which shows the structure of the chelating agent reproduction | regeneration part which makes a part of sand / soil purification part shown in FIG. It is a typical partial cross section side view which shows the structure of the sand rinse part which makes a part of sand / soil purification part shown in FIG. It is a typical partial cross section side view which shows the structure of the soil rinse part which makes a part of sand / soil purification part shown in FIG. It is a typical top view which shows the structure of the soil purification system (except for a chelating agent reproduction | regeneration part) shown in FIG. It is a typical fragmentary sectional elevational view of the sand accommodating part, the washing | cleaning wastewater spraying apparatus, and the roof cut | disconnected by the plane perpendicular | vertical to the longitudinal direction (front-back direction) of a sand accommodating part. It is a typical top view of the principal part of a sand storage part and a washing wastewater spraying device in the state where a roof and a frame structure were removed.

Hereinafter, a soil purification system and a soil purification method according to embodiments of the present invention will be specifically described with reference to the accompanying drawings.
As shown in FIG. 1, according to the embodiment of the present invention, a soil purification system S for purifying soil containing gravel, sand and soil and contaminated with harmful metals or the like (ie, harmful metals and / or compounds thereof) The soil classification unit 1 wet-classifies contaminated soil into gravel, sand, and soil using washing water, and the sand and soil separated by the soil classification unit 1 are washed with a chelating cleaning solution containing a chelating agent and water. And a sand / soil purification unit 2 for purification.

  As shown in FIG. 2, in the soil classification unit 1, soil (contaminated soil) collected by excavation of ground contaminated with harmful metals or the like or contaminated with other pollutants is received by the input hopper 3. It is done. Then, the soil in the charging hopper 3 is first charged into a container-like mixer 4 and mixed with washing water in the mixer 4. Here, the soil is a gravel (particle size is 2 to 75 mm) of various particle sizes, sand (particle size is 0.075 to 2 mm), soil (silt or clay having a particle size of 0.075 mm or less), Is included. The soil in the input hopper 3 is contaminated with harmful metals and the like, and in some cases is further contaminated with other contaminants. Here, examples of harmful metals include chromium, lead, cadmium, selenium, mercury, metal arsenic, and compounds thereof. The chelate cleaning liquid described later can effectively capture (remove) such harmful metals and the like.

  A mixture of soil and washing water generated by the mixer 4 (hereinafter referred to as “soil / water mixture”) is transferred to the mill breaker 5. For example, a rod mill can be used as the mill breaker 5. Although not shown in detail, the rod mill is a device in which a plurality of rods are arranged in a drum, and the rods roll in parallel with each other due to the rotation of the drum and make line contact with each other. To remove harmful metals attached to or adhered to the gravel and separate them from the gravel. Most of the harmful metals and the like that have separated into the washing water adhere to the surface of the sand and soil (fine-grained soil) particles.

  The soil / water mixture discharged from the mill breaker 5 is introduced into the trommel 6. Although not shown in detail, the trommel 6 is a wet sieving device having a receiving tank capable of storing cleaning water and a substantially cylindrical drum screen arranged to be inclined with respect to a horizontal plane. The drum screen can be rotated around its central axis by a motor. In addition, cleaning water can be sprayed into the drum screen.

  When the soil / water mixture flows inside the rotating drum screen of the trommel 6, the soil particles (sand, soil) finer than the mesh of the drum screen pass through the mesh of the drum screen together with the washing water, and come out of the drum screen. Exit and enter the tank. On the other hand, soil particles (pebbles) that are coarser than the mesh of the drum screen cannot pass through the mesh of the drum screen, and are thus discharged out of the drum screen via the opening end on the lower side of the drum screen.

  The classified diameter (opening) of the mesh of the drum screen is set so that, for example, soil particles (sand, soil) having a particle size of less than 2 mm pass through the mesh of the drum screen. Therefore, in the trommel 6, soil particles (that is, gravel) having a particle size of 2 mm or more are separated from the soil / water mixture. Note that the mesh size (opening) of the drum screen of the trommel 6 is not limited to that described above, and is arbitrarily set according to the particle size of the soil particles having a relatively large particle size to be obtained. be able to.

  A soil / water mixture containing soil particles (sand, soil) having a particle size of less than 2 mm and wash water contained in a trough 6 receiving tank is introduced into the hydrocyclone 7. Although not shown in detail, the hydrocyclone 7 generates a swirling flow by pumping the soil / water mixture in a substantially conical cylinder that narrows downward, and utilizes the centrifugal force generated thereby. , Soil / water mixture, soil with relatively small particle size (eg less than 0.075 mm) and wash water (most wash water) and relatively large particle size sand (eg 0.075 mm) And a mixture of washing water (the washing water ratio is small). A mixture of soil and washing water (hereinafter referred to as “soil-containing water”) is discharged from the upper end of the hydrocyclone 7, and a mixture of sand and washing water is discharged from the lower end of the cyclone 7. Then, the soil-containing water is transferred to the PH adjustment tank 8. The soil contained in the soil-containing water is, for example, silt or clay having a particle size of less than 0.075 mm. The mixture of sand and washing water discharged from the lower end of the hydrocyclone 7 is transferred to the sand / soil purification unit 2 (see FIG. 3) after reducing the washing water ratio using, for example, a vibrating sieve. .

  The soil-containing water discharged from the cyclone 7 is introduced into the pH adjusting tank 8, and its pH (hydrogen index) is adjusted to a pH adjusting agent such as an acid solution (for example, sulfuric acid or hydrochloric acid) and an alkali solution (for example, sodium hydroxide). Using an aqueous solution or the like, the pH is adjusted to almost neutral or a predetermined pH (for example, pH 7 to 8). Although not shown, in the pH adjusting tank 8, the pH of the soil-containing water is automatically adjusted by an automatic control device equipped with a pH meter or the like.

  The soil-containing water whose pH is adjusted in the pH adjusting tank 8 is introduced into the coagulating tank 9. In the coagulation tank 9, a polyaluminum chloride liquid (PAC), a polymer coagulant, and a pH adjuster (acid solution or alkali solution) are added to the soil-containing water. As a result, a large number of flocs in which water-insoluble metal hydroxide and soil are mixed are generated in the aggregation tank 9.

  Soil-containing water containing a large number of flocs in the coagulation tank 9 is introduced into the thickener 10. Although the thickener 10 is not shown in detail, the floc or soil is settled by gravity in a state where the soil-containing water is almost stationary, and a sludge layer (for example, the solid content ratio is 5 to 10%) located below. ) And supernatant water (wash water) which is located at the top and hardly contains flock or soil. When the floating oil is floating on the surface of the supernatant water, the floating oil can be removed by, for example, floating an oil absorbing mat on the surface of the thickener 10 and collecting the oil absorbing mat appropriately. it can.

  The supernatant water in the thickener 10 is introduced into the wash water storage tank 11 and stored. The washing water stored in the washing water storage tank 11 is supplied to the mixer 4 and the trommel 6. In addition, when the wash water stored in the wash water storage tank 11 is reduced by evaporation or the like, water (industrial water, tap water, etc.) is appropriately replenished.

  On the other hand, the sludge accumulated in the lower part of the thickener 10 is transferred to the intermediate tank 12 and temporarily stored. Then, the sludge in the intermediate tank 12 is transferred to the filter press 13 as appropriate or continuously. Although not shown in detail, the filter press 13 is a batch-type or semi-continuous type pressure filter, and the sludge received from the intermediate tank 12 is pressure-filtered to obtain a filter cake (soil) and a filtrate (washing). Water). The filtration pressure of the filter press 13 is preferably set so that, for example, the moisture content of the filter cake is 30 to 40%. Here, the filtrate of the filter press 13 is returned to the thickener 10, and the filter cake (soil) is transferred to the sand / soil purification unit 2 (see FIG. 3). Thus, the wash water is circulated and used in the soil classification unit 1 and is not discharged to the outside. That is, the soil classification unit 1 is a closed system with respect to the washing water.

  As shown in FIG. 3, the sand / soil purification unit 2 includes a sand cleaning unit 14, a soil cleaning unit 15, a chelating agent regeneration unit 16, a sand rinsing unit 17, a soil rinsing unit 18, and a chelating agent recovery unit. 19. Here, the sand washing | cleaning part 14 wash | cleans the sand discharged | emitted from the liquid cyclone 7 with the chelate washing | cleaning liquid containing a chelating agent and water, and removes a harmful metal etc. from this sand. The soil washing part 15 wash | cleans the soil (filter cake) discharged | emitted from the filter press 13 with a chelate washing | cleaning liquid, and removes a harmful metal or its compound from this soil. The chelating agent regeneration unit 16 regenerates the chelating cleaning solution by removing harmful metals from the chelating agent in the chelating cleaning solution discharged from the sand cleaning unit 14 and the soil cleaning unit 15. Return it. The sand rinsing unit 17 removes the chelating agent by washing the sand discharged from the sand washing unit 14 with rinsing water. The soil rinsing unit 18 cleans the soil discharged from the soil cleaning unit 15 with rinsing water and removes the chelating agent. The chelating agent recovery unit 19 recovers the chelating agent from the cleaning wastewater containing the chelating agent discharged from the sand rinsing unit 17 and the soil rinsing unit 18.

  As shown in FIG. 4, the sand cleaning unit 14 includes a flow type mixing stirrer 21, a vibrating sieve 22, and a vacuum suction type belt conveyor 23. The mixing stirrer 21 is a device for mixing and stirring the sand discharged from the hydrocyclone 7 and the chelate cleaning liquid, and trapping harmful metals or the like adhering to or bound to the sand by the chelating agent. The vibrating sieve 22 is a device for removing most of the chelate cleaning liquid from the mixture of sand and chelate cleaning liquid discharged from the mixing stirrer 21. The vacuum suction type belt conveyor 23 receives the sand wet with the chelate cleaning liquid discharged from the vibration sieve 22, and vacuum-sucks the sand through the filter medium mounting belt 36 while conveying the sand with the filter medium mounting belt 36. It is an apparatus for significantly reducing the content of chelate cleaning solution (or chelate cleaning solution content) of the sand.

  Specifically, the mixing stirrer 21 includes an elongated substantially cylindrical main body 25 whose central axis extends in the vertical direction, and a plurality of baffle plates 26 (baffle plates) attached to the inner peripheral surface of the main body 25. A stirrer 27 disposed in the main body 25 and a motor 28 that rotationally drives the stirrer 27 are provided. Each baffle plate 26 is basically annular with a hole formed in the center thereof, but in order to facilitate the downward movement of sand, it is tapered so as to incline downward. Is formed.

  The stirrer 27 has a plurality of stirring blades or blades attached to a rotating shaft extending in the vertical direction. The shape or size of the stirring blade is set so that it can pass through the hole of each baffle plate 26. Here, the baffle plates 26 and the stirring blades of the stirrer 27 are arranged so as to be alternately arranged in the vertical direction.

  The dimensions (for example, diameter, height, etc.) of the main body 25 ensure that the chelate cleaning liquid and sand particles flowing in the main body 25 have a preset residence time (for example, 0.1 to 0.3 hours). It is preferably set so that it can be performed. The number, shape, rotational speed, and the like of each stirring blade of the stirrer 27 are determined according to the degree of turbulence (for example, Reynolds number 20000 to 100,000) in which the sand particles are dispersed almost uniformly in the chelate cleaning liquid in the main body 25. ) Is preferably set to be achieved.

  Then, the sand and the chelate cleaning liquid are supplied to the upper end opening of the main body 25, and the chelate cleaning liquid and the sand particles are stirred and mixed by the stirrer 27. As a result, a mixture in which the sand particles are dispersed almost uniformly in the chelate cleaning liquid (hereinafter referred to as “sand / cleaning liquid mixture”) is generated, and this sand / cleaning liquid mixture is stirred by a plurality of stirring blades of the stirrer 27. The main body 25 flows downward at a slow speed as a whole. Thus, in the mixing stirrer 21 (main body portion 25), the sand particles are brought into contact with the chelate cleaning liquid, and harmful metals attached to the surface of the sand particles in the sand / cleaning liquid mixture are removed. The baffle plate 26 increases the degree of turbulence (Reynolds number) of the sand / cleaning liquid mixture in the main body 25, thereby promoting the removal or removal of harmful metals from the sand particles.

  Examples of the chelating agent used in the chelate cleaning solution include EDTA (ethylenediaminetetraacetic acid), HIDS (3-hydroxy-2,2′-iminodisuccinic acid), IDS (2,2′-iminodisuccinic acid), MGDA (methylglycine). Diacetic acid), EDDS (ethylenediaminediacetic acid) or sodium salt of GLDA (L-glutamic acid diacetic acid). Any of these chelating agents can effectively capture (chelate) harmful metals attached to or bound to sand particles. Note that a chelating agent suitable for the treatment is selected or a plurality of chelating agents are used depending on the type of harmful metal adhering to or bound to the sand.

  After harmful metals are removed from the sand in this way, the sand / cleaning liquid mixture is introduced into the vibrating sieve 22 from the lower end opening of the main body 25, and most of the chelate cleaning liquid is separated from the sand / cleaning liquid mixture. . As the vibrating screen 22, a tilted vibrating screen machine in which a wire mesh 30 having a preset mesh opening (diameter) is disposed in an inclined manner in the casing 31 is used. A circular vibrating screen or the like may be used. Moreover, you may use a stationary inclination sieve instead of a vibration sieve. As the wire mesh 30 of the vibration sieve 22, a mesh (diameter) that does not allow sand particles to pass therethrough is used. The chelate cleaning liquid that has passed through the wire mesh 30 is introduced into the cleaning liquid storage tank 33 through the pipe 32 and stored. The chelate cleaning liquid stored in the cleaning liquid storage tank 33 is transported to the chelating agent regeneration unit 16 described later.

  On the other hand, sand that does not pass through the wire mesh 30 of the vibrating screen 22 is introduced into the vacuum suction belt conveyor 23. The sand introduced into the vacuum suction belt conveyor 23 is wetted with the chelate cleaning liquid, and the content of the chelate cleaning liquid is considerably high (for example, 20 to 40%). Therefore, the sand is vacuum-sucked by the vacuum suction belt conveyor 23 to reduce the content of the chelate cleaning liquid in the sand as much as possible.

  The vacuum suction type belt conveyor 23 includes a first roller 34 and a second roller 35 having the same diameter, and a ring-shaped or endless filter medium mounting belt wound around the first roller 34 and the second roller 35. 36. Here, the first roller 34 is a driven roller, and the second roller 35 is a driving roller driven by a motor (not shown). The first roller 34 and the second roller 35 are arranged at the same height, and the filter medium mounting belt 36 travels in the horizontal direction at a portion where it does not contact the first roller 34 or the second roller 35. The filter medium mounting belt 36 is supported by a plurality of support rollers (not shown) when traveling on the upper horizontal travel path. Here, the filter medium mounting belt 36 conveys sand wet with the chelate cleaning liquid supplied from the vibrating sieve 22 in the horizontal direction (rightward in the positional relationship in FIG. 4).

  In the vertical direction, a decompression chamber 37 is provided between the upper horizontal traveling path and the lower horizontal traveling path of the filter medium mounting belt 36. The decompression chamber 37 is a container having an upper opening, and the upper opening of the decompression chamber 37 is closed by a filter medium mounting belt 36 that travels on the upper horizontal travel path. The decompression chamber 37 is connected to a vacuum pump (not shown) through an exhaust pipe 38, and the air in the decompression chamber 37 is sucked and exhausted by the vacuum pump, and the decompression chamber 37 is in a decompressed state.

  The decompression chamber 37 is connected to the cleaning liquid storage tank 33 through a drain pipe 39. Here, the drainage pipe 39 is 10 m or longer downward so that air does not flow backward and the chelate cleaning liquid is discharged downward without any trouble even when the decompression chamber 37 is in a decompressed state or a vacuum state. It is growing. And the lower end part of the drainage pipe | tube 39 is immersed in the chelate washing | cleaning liquid in the washing | cleaning liquid storage tank 33 so that the decompression chamber 37 can maintain a pressure reduction state or a vacuum state (so that air does not flow in).

  Thus, the sand moistened with the chelate cleaning liquid supplied to the filter medium mounting belt 36 in the portion traveling on the upper horizontal traveling path is sucked by the decompression chamber 37 in a decompressed state or a vacuum state while being transported, and the sand Most of the chelate cleaning liquid held between the particles is sucked into the decompression chamber 37 via the filter medium mounting belt 36. Further, the chelate cleaning solution remaining and adhering to the sand particles is discharged into the decompression chamber 37 by the air flowing at high speed into the decompression chamber 37 through the interparticle voids of the sand layer on the filter medium mounting belt 36. Thereby, the chelate washing liquid content ratio of the sand on the filter medium mounting belt 36 becomes very small (for example, 5 to 10%). Thus, the sand whose chelate cleaning liquid content ratio is reduced is scraped off by the scraper 40 and transferred to the sand rinsing section 17 described later.

  On the other hand, the chelate cleaning liquid in the decompression chamber 37 flows down to the cleaning liquid storage tank 33 by gravity. As described above, the drainage pipe 39 extends downward for 10 m or longer, and its lower end is immersed in the chelate cleaning liquid in the cleaning liquid storage tank 33, so that air flows into the decompression chamber 37 via the drainage pipe 39. Never do.

  Hereinafter, the configuration and function of the soil cleaning unit 15 will be described with reference to FIGS. 5 and 6A to 6C. The soil cleaning unit 15 includes a mixing / dispersing device 15A, a soil cleaning device 15B, and a filtration device (not shown). The mixing / dispersing device 15A mixes the soil discharged from the filter press 13 and the chelate cleaning liquid, and generates a soil dispersion slurry in which the soil is dispersed in the chelate cleaning liquid. The soil cleaning device 15B causes the soil dispersion slurry generated by the mixing / dispersing device 15A to flow through a plug flow so as to ensure a preset residence time while stirring, thereby removing harmful metals attached to the soil. Remove from the soil and trap with chelating agents. The filtration device (not shown) filters the soil dispersion slurry discharged from the soil cleaning device 15B. In addition, as a filtration apparatus, a vacuum filter, a filter press, etc. can be used.

  As shown in FIG. 5, the mixing and dispersing device 15 </ b> A that forms part of the soil washing unit 15 is crushed by the crusher 41 that crushes the soil (filter cake) discharged from the filter press 13 and the crusher 41. A premixing tank 42 for premixing the soil pieces and the chelate washing liquid, and the mixture produced by the premixing tank 42 are stirred to make the earth pieces (for example, the particle size is about several 0.1 to 0.5 mm or 0 And a line mixer 43 for dispersing or suspending particles in the chelate cleaning solution.

  In the mixing and dispersing device 15A, the soil (filter cake) discharged from the filter press 13 is supplied to the crusher 41, and the soil has a particle size of, for example, several mm (for example, 1 to 5 mm) by a blade 41a that rotates at high speed. ) Is broken into a large number of small pieces of earth. On the other hand, the chelate cleaning liquid in the chelate cleaning liquid storage tank 44 is supplied to the crusher 41 by the pump 45 via the conduit 46. Although not shown in detail, the chelate cleaning liquid is sprayed or supplied to a large number of pieces of soil immediately after being crushed by the blade 41a, and prevents the pieces of soil from adhering to each other. As such a crusher 41, for example, a “dehydrated cake crusher” according to Taiheiyo Kiko Co., Ltd. or a “dehydrated cake recycling device” according to Shoko Co., Ltd. can be used. In the case of using a commercially available crusher, it is necessary to provide a mechanism for injecting or supplying the chelate cleaning liquid to a large number of pieces of soil immediately after crushing.

  The chelate cleaning liquid and the soil pieces in the crusher 41 are transferred to the premixing tank 42. The chelate cleaning liquid and the small soil pieces in the premixing tank 42 are stirred and premixed by a stirrer 47 that is driven to rotate by a motor. Then, the mixture of the chelate cleaning solution and the soil pieces in the premixing tank 42 is transferred to the line mixer 43 by the pump 48 via the conduit 49. The line mixer 43 is a flow-type mixer in which a blade that is rotated at a very high speed by a motor is arranged in a horizontal cylindrical stirring chamber, and the chelate cleaning solution and the soil pieces are stirred very vigorously. Then, soil or soil fine particles (for example, particles having a particle size of about 0.1 to 0.5 mm or about 0.1 to 1 mm) are dispersed (suspended) almost uniformly in the cleaning liquid. A dispersed slurry is produced. The soil dispersion slurry is transferred to the soil cleaning device 15B. As such a line mixer 43, for example, “Satake Multi Line Mixer” according to Satake Chemical Machinery Co., Ltd. can be used.

  As shown in FIGS. 6 (a) to 6 (c), the soil cleaning device 15B has five elongated rectangular parallelepiped shapes or prismatic shapes that are formed by partitioning with four flat partition walls 51 to 54 and extend in parallel to each other. It has the storage tank 50 provided with the water channels 55-59. Here, the storage tank 50 may be, for example, an iron rectangular parallelepiped tank installed on the ground, or may be a concrete rectangular parallelepiped pit. Moreover, the partition walls 51-54 may be formed by, for example, connecting a plurality of iron plates or plastic plates in the direction in which the water channel extends.

  In these water channels 55 to 59, two adjacent water channels are in the form of four curved lines in one end of the channel in the longitudinal direction of the water channel (left and right in the positional relationship in FIGS. 6A and 6B) (FIG. 6A). The parts indicated by arrows in FIG. That is, the partition walls 51 to 54 do not exist in these communicating portions, and adjacent water channels communicate with each other.

  Air discharge pipes 61 to 65 for discharging air into the soil dispersion slurry and stirring the soil dispersion slurry are disposed at the bottoms of the water channels 55 to 59, respectively. Each of the air discharge pipes 61 to 65 is a porous pipe extending in the longitudinal direction of the water channel and having a plurality of air discharge holes arranged in the longitudinal direction of the water channel at the bottom (lower side) of the peripheral wall. Not connected to a compressor or blower that supplies compressed air. When pressurized air is supplied to the air discharge pipes 61 to 65, the air is discharged as bubbles from the air discharge holes into the soil dispersion slurry and floats, and the soil dispersion slurry is stirred by the bubbles. .

  FIG. 6C shows a cross section of the water channel 55 on the most upstream side in the flow direction of the soil dispersion slurry (the direction indicated by the curved arrow and the straight arrow in FIG. 6A). As is clear from FIG. 6C, the air discharge pipe 61 is disposed near the bottom of the water channel in the vicinity of one side surface of the water channel 55. For this reason, the bubbles discharged from the air discharge pipe 61 rise in the vicinity of this side surface. As a result, a circulating flow that flows in the direction indicated by the arrow P in a plane perpendicular to the longitudinal direction of the water channel is formed in the water channel 55, and the soil dispersion slurry is effectively stirred. The shape, size, capacity, etc. of the storage tank 50 and each water channel 55-59, the supply amount of pressurized air to the air discharge pipes 61-65, etc. are the moisture content of the soil dispersion slurry preset in the soil washing apparatus 15B. , Flow rate, residence time, flow rate, flow turbulence (for example, Reynolds number) and the like are preferably set.

  As shown in FIG. 7, the chelating agent regeneration unit 16 has a solid adsorbent particle or a packing (packing) in which the solid adsorbent is fixed as a means for regenerating the chelate cleaning solution or chelating agent. A packed tower 71 (chelate cleaning liquid regenerator) is provided. The chelating agent regeneration unit 16 includes an intermediate storage tank 72 that stores a chelate cleaning liquid to be regenerated, a regenerated chelate cleaning liquid storage tank 73 that stores the regenerated chelate cleaning liquid, an acid liquid storage tank 74 that stores an acid liquid, and water. And a water storage tank 75 for storing the water.

  In the intermediate storage tank 72, a chelate cleaning liquid introduced from the cleaning liquid storage tank 33 (see FIG. 4) of the sand cleaning section 14 and a chelate cleaning liquid (filtrate) discharged from a filtration device (not shown) of the soil cleaning section 15 are stored. Stored temporarily. When the chelate cleaning liquid is regenerated, the chelate cleaning liquid stored in the intermediate storage tank 72 is transferred to the packed tower 71, while the chelate cleaning liquid regenerated in the packed tower 71 is transferred to the regenerated chelate cleaning liquid storage tank 73. And a series of a plurality of pipes 77-80 are provided. Further, a pump 81 and a pipe line 82 are provided for supplying the chelate cleaning liquid stored in the regenerated chelate cleaning liquid storage tank 73 to the sand cleaning section 14 (mixing agitator 21) and the soil cleaning section 15 (chelate cleaning liquid storage tank 44). ing.

  Further, when the solid phase adsorbent is regenerated, the chelating agent regeneration unit 16 transfers the acid solution stored in the acid solution storage tank 74 to the packed tower 71, while the acid solution discharged from the packed tower 71 is acidified. A pump 83 and a plurality of pipes 84 and 85 for returning to the liquid storage tank 74 are provided. In addition, when the solid-phase adsorbent regenerated with the acid solution is washed with water, the chelating agent regeneration unit 16 transfers water stored in the water storage tank 75 to the packed tower 71 while being discharged from the packed tower 71. A pump 86 and a plurality of pipes 87 and 88 for returning water to the water storage tank 75 are provided.

  Here, valves 91, 92, 93, and 94 for opening and closing the corresponding pipe lines are respectively connected to the pipe lines 77, 78, 84, and 87 for transferring the chelate cleaning solution, the acid solution, and the water to the packed tower 71. It is installed. On the other hand, valves 79, 80, 85 and 88 for discharging the chelate cleaning liquid, acid solution or water from the packed tower 71 are provided with valves 95, 96, 97 and 98 for opening and closing the corresponding pipe lines, respectively. Has been. By switching the open / close states of these valves 91 to 94 and 95 to 98, any of the chelate cleaning solution, the acid solution, and water can be supplied to and discharged from the packed tower 71. In addition, opening / closing of these valves 91-94 and 95-98 is automatically controlled by a controller (not shown).

  Hereinafter, an example of the operation method of the chelating agent regeneration unit 16 will be described. In addition, the driving | operation method demonstrated below is a mere illustration, and of course, the driving | operation method of the chelating agent reproduction | regeneration part 16 which concerns on this invention is not limited to the following. When regenerating the chelate cleaning liquid (chelating agent), the valves 91, 92, 95, 96 interposed in the pipe lines 77-80 are opened, while the other valves 93, 94, 97, 98 are closed, The pump 76 is operated. Thereby, the chelate cleaning liquid in the intermediate storage tank 72 flows through the packed tower 71 and is transferred to the regenerated chelate cleaning liquid storage tank 73.

  Thus, in the packed tower 71, the chelate cleaning liquid containing the chelating agent capturing toxic metals and the like is brought into contact with the solid phase adsorbent (solid phase adsorbent particles) having a higher complexing power than the chelating agent. As a result, harmful metals and the like captured by the chelating agent are separated from the chelating agent and adsorbed or extracted by the solid phase adsorbent. As a result, harmful metals and the like are removed and recovered from the chelate cleaning solution, while the chelating agent is again in a state where it can capture the harmful metals and the chelate cleaning solution is regenerated. The chelate cleaning solution stored in the regenerated chelate cleaning solution storage tank 73 is returned by the pump 81 to the sand cleaning unit 14 and the soil cleaning unit 15 through the pipe line 82.

  A solid-phase adsorbent having a higher complexing power than a chelating agent is a solid material such as a gel, and is generally coordinated with a chelating agent when contacted with an aqueous solution containing a chelating agent capturing a metal. It has a strong binding force other than a covalent bond to such an extent that the metal ions can be detached from the chelating agent and transferred to the solid phase adsorbent. Examples of such a solid-phase adsorbent include a material in which a cyclic molecule is densely supported on a carrier such as silica gel or a resin and a chelate ligand is modified on the cyclic molecule. When such a solid-phase adsorbent is used, a plurality of various bonds and interactions such as coordination bonds and hydrogen bonds occur due to adjacent cyclic molecules and chelate ligands, resulting in multipoint interactions, and metal ions In contrast to this, a chemical bond stronger than that of a chelating agent is generated, and metal ions can be selectively taken in by the properties of the cyclic molecule.

  As the chelate cleaning solution is regenerated, the amount of adsorption of harmful metals and the like in the solid-phase adsorbent increases with time, but there is an upper limit on the adsorption capacity of the solid-phase adsorbent. For this reason, when the amount of adsorption of harmful metals or the like in the solid phase adsorbent reaches a saturated state or the vicinity thereof, the solid phase adsorbent is regenerated. That is, the acid solution is flowed into the packed tower 71 with the chelate cleaning solution removed, and harmful metals adsorbed on the solid phase adsorbent are removed by the acid solution to regenerate the solid phase adsorbent. Thus, while the toxic metal and the like are recovered by the acid solution, the solid phase adsorbent is regenerated and becomes capable of adsorbing or extracting the toxic metal and the like or these ions again. The solid phase adsorbent is regenerated with an acid solution and then washed with water to remove a small amount of acid solution adhering to the solid phase adsorbent.

  When the amount of adsorption of harmful metals or the like of the solid-phase adsorbent in the packed tower 71 reaches a saturated state or in the vicinity thereof, the solid-phase adsorbent is regenerated with an acid solution. The provided valves 93, 92, 95, 97 are opened, while the other valves 91, 94, 96, 98 are closed, and the pump 83 is operated. As a result, the acid solution in the acid solution storage tank 74 flows through the packed tower 71 and returns to the acid solution storage tank 74. Before starting the regeneration operation of the solid-phase adsorbent, the chelate cleaning liquid in the packed tower 71 is removed. If a plurality of packed towers 71 are arranged in parallel, the chelate cleaning liquid can be regenerated continuously even when the supply of the chelate cleaning liquid to some of the packed towers 71 is stopped. Whether or not the amount of harmful metal adsorption of the solid-phase adsorbent reaches a saturated state or in the vicinity thereof can be determined by detecting the content of harmful metal or the like in the chelate cleaning liquid discharged from the packed tower 71. .

  The time for which the acid solution is allowed to flow into the packed column 71 is preferably set according to the size or shape of the packed column 71, the size of the solid-phase adsorbent particles, and the like. The acid solution circulates through the acid solution storage tank 74 and the packed tower 71. At that time, the solid-phase adsorbent in the packed tower 71 comes into contact with the acid solution, and harmful metals and the like adsorbed on the solid-phase adsorbent are separated into the acid solution. That is, while the harmful metal and the like are recovered by the acid solution, the solid-phase adsorbent is regenerated to be able to adsorb the harmful metal and the like again.

  When the solid-phase adsorbent is washed with water after the regeneration of the solid-phase adsorbent with the acid solution is completed, the valves 94, 92, 95, 98 provided in the pipes 87, 78, 79, 88 are opened. The other valves 91, 93, 96, 97 are closed and the pump 86 is operated. Thereby, the water in the water storage tank 75 flows through the packed tower 71 and returns to the water storage tank 75. Before the washing operation of the solid phase adsorbent is started, the acid solution in the packed tower 71 is removed. Water circulates between the water storage tank 75 and the packed tower 71 and flows. At that time, the solid phase adsorbent in the packed tower 71 comes into contact with water, and the acid solution adhering to the solid phase adsorbent is washed. Thereafter, regeneration of the chelate cleaning solution is resumed.

  As shown in FIG. 8, the sand rinsing unit 17 (sand rinsing device) includes a belt conveyor 100, a sand supply device 101, a rinsing water spraying device 102, and a washing waste water receiving tank 103. Here, the belt conveyor 100 is coaxially attached to a substantially cylindrical drive roller 104 that is coaxially attached to a shaft 104a that is rotationally driven by an electric motor (not shown), and a shaft 105a that is not connected to a drive source. A substantially cylindrical driven roller 105, a ring-shaped or endless conveying belt 106 wound around the driving roller 104 and the driven roller 105, and a number of supporting rollers 107 that support or guide the conveying belt 106. , And a guide plate 108 for guiding the sand discharged from the belt conveyor 100.

  The driving roller 104 and the driven roller 105 have the same diameter and are disposed at the same height. The conveyor belt 106 is made of a porous material, mesh material, fibrous material, or cloth material that can be curved in a ring shape that allows rinsing water to pass but not sand particles. The rinse water spraying device 102 sprays rinse water on the sand transported by the transport belt 106 in a region having a predetermined length (for example, 1 to 2 m) in the moving direction of the transport belt 106. The amount of rinse water sprayed from the rinse water spray device 102 is preferably set so that the chelate cleaning liquid adhering to the sand can be washed away almost entirely. For example, the amount of rinse water 1.5 to 2.0 times the amount of chelate cleaning liquid adhering to the sand is sprayed. As a specific example, for example, when sand having a chelate cleaning liquid content ratio of 10% is transported at 5 tons (dry basis) per hour, 0.75 to 1.0 tons of rinse water is sprayed per hour. Become.

  The sand supply device 101 supplies the sand discharged from the sand cleaning unit 14 on the conveying belt 106 in the vicinity of the driven roller 105 at a predetermined flow rate. The sand thus supplied is conveyed by the conveyor belt 106, falls downward through the guide plate 108 at a position corresponding to the drive roller 104, and is stored in a sand storage (not shown). Rinsing water is sprayed from the rinse water spraying device 102 onto the sand transported by the transport belt 106. The rinse water moves downward through the gap between the sand particles, passes through the conveyor belt 106, and flows down or falls as washing waste water into the washing waste water receiving tank 103. At that time, the chelate cleaning liquid adhering to the sand is washed downward by the rinsing water and flows into or falls into the cleaning waste water receiving tank 103.

  Thus, sand containing no chelating agent is stored in a sand storage tank (not shown). On the other hand, the cleaning wastewater containing the chelating agent in the cleaning wastewater receiving tank 103 of the sand rinsing unit 17 is introduced into the cleaning wastewater evaporator 131 (see FIG. 10) of the chelating agent recovery unit 19. The chelating agent is recovered from the cleaning wastewater by the cleaning wastewater evaporator 131, and the chelating agent is returned to the sand cleaning unit 14 together with the sand.

  In order to further reduce the amount of rinse water used in the sand rinsing unit 17, that is, the amount of discharged cleaning waste water, the belt conveyor 100 is the same as the vacuum suction belt conveyor for the sand cleaning unit 14 shown in FIG. It may be used. In this case, the downward flow of rinsing water or washing wastewater is promoted by the air flowing into the decompression chamber at high speed through the interparticle voids of the sand layer on the filter media mounting belt, so the amount of rinsing water used is greatly increased. Can be reduced.

As shown in FIG. 9, the soil rinsing unit 18 includes a soil crusher 110 and a soil rinsing device 111. Here, the soil crusher 110 crushes the soil (filter cake) discharged from the filtration device (not shown) of the soil cleaning device 15B that forms a part of the soil cleaning unit 15 to break up the particles or powder. Generate crushed soil. The soil rinsing device 111 sprays or sprays rinsing water on the crushed soil generated by the soil pulverizer 110 to remove (recover) the chelating agent held in the crushed soil.

  The soil crusher 110 has a particle size of, for example, a few mm (for example, 1 to 3 mm) by using a blade 112 that rotates the soil (filter cake) discharged from the filtration device (not shown) of the soil cleaning device 15B at high speed. Break into many pieces. The soil rinsing device 111 includes a belt conveyor 114, a crushed soil receiving unit 115, a rinsing water spraying device 116, and a washing waste water receiving tank 117. The belt conveyor 114 has a substantially cylindrical drive roller 118 coaxially attached to a shaft 118a that is rotationally driven by an electric motor (not shown), and a substantially coaxially attached shaft 119a that is not connected to a drive source. A cylindrical driven roller 119, a ring-shaped or endless conveying belt 120 wound around the driving roller 118 and the driven roller 119, a number of supporting rollers 121 that support or guide the conveying belt 120, and the belt And a guide plate 122 for guiding the crushed soil discharged from the conveyor 114.

  The driving roller 118 and the driven roller 119 have the same diameter and are disposed at the same height. The conveyor belt 120 is made of a porous material, mesh material, fibrous material, or cloth-like material that can be curved in a ring shape that allows rinsing water to pass but not crushed soil particles. The rinsing water spraying device 116 sprays rinsing water on the crushed soil transported by the transport belt 120 in a region having a predetermined length (for example, 1 to 2 m) in the moving direction of the transport belt 120. The amount of rinse water sprayed from the rinse water spray device 116 is preferably set so that almost all of the chelate cleaning solution adhering to the crushed soil can be washed away. For example, an amount of rinsing water that is 1.2 to 2.0 times the amount of the chelate cleaning solution adhering to the crushed soil is sprayed.

  The crushed soil receiving unit 115 supplies the crushed soil discharged from the soil pulverizer 110 onto the conveyor belt 120 at a predetermined flow rate in the vicinity of the driven roller 119. The crushed soil supplied in this manner is transported by the transport belt 120, falls downward via the guide plate 122 at a position corresponding to the drive roller 118, and is stored in a soil storage (not shown). Rinse water is sprinkled from the rinse water spraying device 116 to the crushed soil transported by the transport belt 120, and the rinse water moves downward through the gaps between the particles of the crushed soil and passes through the transport bell 120 for cleaning. It flows down to the waste water receiving tank 117. At this time, the chelate cleaning liquid adhering to the crushed soil is washed downward by the rinse water and flows down to the washing waste water receiving tank 117. Here, a part of rinse water is hold | maintained in the clearance gap between the particles of crushed soil. That is, the chelate cleaning liquid held or attached to the crushed soil is replaced with rinsing water. That is, the chelating agent contained in or adhering to the crushed soil is washed away by the rinsing water and stored in the washing waste water receiving tank 117 together with the rinsing water (part). Thus, soil containing no chelating agent is stored in a soil storage (not shown). The cleaning wastewater containing the chelating agent accommodated in the cleaning wastewater receiving tank 117 of the soil rinsing device 111 is introduced into the cleaning wastewater evaporator 131.

  In order to further reduce the amount of rinse water used in the soil rinsing device 111, that is, the discharge amount of washing waste water, the belt conveyor 114 is the same as the vacuum suction belt conveyor for the sand cleaning unit 14 shown in FIG. It may be used. In this case, the downward movement of the rinsing water or washing waste water is promoted by the air flowing into the decompression chamber at high speed through the interparticle voids of the pulverized soil layer on the filter belt, so the amount of rinsing water used Can be greatly reduced.

  Thus, the cleaning waste water (rinsing water containing the chelating agent) accommodated in the cleaning waste water receiving tanks 103 and 117 of the sand rinsing unit 17 and the soil rinsing unit 18 is introduced into the cleaning waste water evaporator 131 of the chelating agent recovery unit 19. . Then, the cleaning waste water evaporator 131 recovers the chelating agent from the cleaning waste water and returns it to the sand cleaning unit 14.

Hereinafter, the configuration and function of the cleaning waste water evaporator 131 of the chelating agent recovery unit 19 will be described in detail.
As shown in FIGS. 10 to 12, the cleaning wastewater evaporator 131 of the chelating agent recovery unit 19 includes a cleaning wastewater receiving tank 103 (see FIG. 8) of the sand rinsing unit 17 and a cleaning wastewater receiving tank 117 of the soil rinsing unit 18 (see FIG. 10). 9 is provided with a cleaning waste water storage tank 134 that receives the cleaning waste water containing the chelating agent discharged from 9) through the cleaning waste water passage 133. The washing waste water storage tank 134 is a concrete water storage tank embedded in the ground and having a rectangular planar shape. Above the cleaning wastewater storage tank 134, a roof (not shown) that prevents rainwater from dropping into the cleaning wastewater storage tank 134 is provided. In the following, the cleaning wastewater storage tank 134 and the cleaning wastewater passage 133 are aligned in FIG. 10 (in FIG. 10) in order to clearly show the positional relationship between the facility or the apparatus in the chelating agent recovery unit 19 or the cleaning wastewater evaporator 131. Regarding the positional relationship, the side where the cleaning waste water storage tank 134 is located is called “left”, and the side where the washing waste water passage 133 is located is called “right”.

  Further, the cleaning waste water evaporation device 131 is provided with a container-shaped sand storage portion 135 for storing water evaporation sand that is appropriately separated from the cleaning waste water storage tank 134 in a direction perpendicular to the left-right direction. Yes. In this embodiment, fine sand (sand having a particle size of 0.075 to 0.25 mm) is used as such water evaporation sand. In the following description, the cleaning wastewater storage tank 134 and the sand container 135 are arranged side by side (in a direction perpendicular to the left-right direction) in order to simply show the positional relationship between the facility or the apparatus in the chelating agent recovery unit 19 or the cleaning wastewater evaporator 131. , The side where the cleaning waste water storage tank 134 is located is referred to as “front”, and the side where the sand container 135 is located is referred to as “rear”.

  The sand container 135 has a front end wall 136, a rear end wall 137, a left side wall 138, a right side wall 139, and a bottom wall 140, and has a relatively short length in the left-right direction and a relatively long length in the front-rear direction. It is a concrete box-like container installed on the ground or buried in the ground, which has a rectangular planar shape and has a depth capable of accommodating an appropriate amount of water evaporating sand. Further, the cleaning wastewater evaporator 131 includes a roof 142 that is disposed above the sand container 135 and prevents rain water from dropping into the sand container 135, and a cleaning agent that contains a chelating agent stored in the cleaning wastewater storage tank 134. A cleaning wastewater spraying device 143 for spraying wastewater onto the water evaporating sand stored in the sand storage unit 135 and a cleaning wastewater recirculation mechanism 144 for returning the cleaning wastewater at the bottom of the sand storage unit 135 to the cleaning wastewater storage tank 134 are provided. ing.

  The sand container 135 is made of concrete and is embedded in the ground 150 so that the vicinity of the upper end of the sand container 135 is exposed to the atmosphere. The sand container 135 has a rectangular shape with a relatively short length in the left-right direction (for example, 20 to 50 m) and a relatively long length in the front-rear direction (for example, 100 to 200 m) in plan view, and its depth. Is configured to accommodate an appropriate amount of water evaporating sand (for example, 0.4 to 0.8 m), and integrally formed front end wall 136, rear end wall 137, left side wall 138, right side wall 139, and bottom It is a box-like (shallow pool-like) container having a wall 140. Note that the lengths of the sand container 135 in the left-right direction and the front-rear direction are appropriately set according to the amount of cleaning waste water evaporated in the sand container 135.

  On the upper surface of the bottom wall 140, a plurality of drainage grooves 151 extending in parallel in the front-rear direction at a predetermined interval and having a predetermined depth (for example, 5 to 10 cm) are provided. These drainage grooves 151 are connected to a collective drainage groove 152 provided in the vicinity of the front end portion of the sand accommodating portion 135. The front end of the collective drainage groove 152 is connected to the cleaning wastewater storage tank 134. The drainage groove 151 and the collective drainage groove 152 are components of the cleaning wastewater recirculation mechanism 144.

  Thus, the cleaning wastewater flowing down through the gaps of the water evaporating sand and flowing into each drainage groove 151 (that is, excess cleaning wastewater that has not evaporated) flows into the cleaning wastewater storage tank 134 by gravity through the collective drainage groove 152. Reflux naturally. A perforated plate 154 that allows cleaning wastewater to pass through but does not allow water evaporation sand to pass therethrough is disposed on the plurality of convex portions 153 that are positioned between the drain grooves 151 in the left-right direction. Here, the perforated plate 154 is not a single plate-like member, but a large number of perforated plates having dimensions suitable for manufacture and transportation (for example, a perforated plate having 1 to 2 m on the left and right, 2 to 5 m on the front and back, and 5 to 10 mm in thickness). It consists of A sand layer 155 having a predetermined thickness (for example, 30 to 60 cm) is formed on the porous plate 154.

  A plurality of left vertical frames 157 are disposed on the left side wall 138 of the sand container 135 with an appropriate interval (for example, 5 to 10 m) in the front-rear direction. A plurality of right vertical frames 158 are arranged at appropriate intervals (for example, 5 to 10 m). Note that the left vertical frame 157 and the right vertical frame 158 are disposed at the same position in the front-rear direction. Then, the vicinity of the upper end of the left vertical frame 157 and the vicinity of the upper end of the right vertical frame 158 disposed at the same position in the front-rear direction are connected by a horizontal frame 159 extending horizontally in the left-right direction. Further, the vicinity of the upper end of the left vertical frame 157 adjacent in the front-rear direction is connected by a vertical frame (not shown) extending in the front-rear direction, and the vicinity of the upper end of the right vertical frame 158 adjacent in the front-rear direction is in the front-rear direction. They are connected by an extending vertical frame (not shown).

  As described above, the roof 142 is mounted on the bowl-shaped frame structure constituted by the left vertical frame 157, the right vertical frame 158, the horizontal frame 159, and the vertical frame (not shown). The roof 142 has a slightly larger planar shape than the sand container 135 so that rainwater can be prevented from descending to the sand container 135 during normal rainfall. Although not shown, the rain that has fallen on the roof 142 is discharged out of the sand container 135 by a rainwater discharger such as a kite and does not flow into the washing wastewater storage tank 134.

  The cleaning wastewater spraying device 143 includes a plurality of water supply pipes 161 that are disposed below the roof 142 above the sand container 135 and extend in the front-rear direction. Although not shown in detail, each water supply pipe 161 is supported by a horizontal frame 159 using a fixture. These water supply pipes 161 are arranged in parallel with an appropriate interval (for example, 1 to 2 m) in the left-right direction. Each water supply pipe 161 is provided with a plurality of water discharge nozzles 162 that open downward with an appropriate interval (for example, 1 to 2 m) in the front-rear direction.

  The front end portion of each water supply pipe 161 extending in the front-rear direction is connected to the rear end portion of the cleaning wastewater supply pipe 164 via an intermediate pipe 163 extending in the left-right direction. In addition, the rear end part of each water supply pipe 161 is closed. The front end of the cleaning wastewater supply pipe 164 is immersed in the cleaning wastewater in the cleaning wastewater storage tank 134. A cleaning wastewater supply pump 165 is interposed in the cleaning wastewater supply pipe 164 in the vicinity of the cleaning wastewater storage tank 134. Here, the cleaning wastewater supply pump 165 sucks and pressurizes the cleaning wastewater in the cleaning wastewater storage tank 134 via the cleaning wastewater supply pipe 164 (the portion on the cleaning wastewater storage tank side from the cleaning wastewater supply pump 165), and pressurizes the cleaning wastewater supply pipe. The water is supplied to each water supply pipe 161 through 164 (the part on the sand accommodating part side from the cleaning wastewater supply pump 165) and the intermediate pipe 163. Thus, cleaning wastewater can be discharged from each water discharge nozzle 162 toward the upper surface of the sand layer 155 (water evaporating sand) in the sand container 135.

  Hereinafter, a method of recovering the chelating agent by treating the cleaning wastewater containing the chelating agent with the chelating agent recovery unit 19 or the cleaning waste water evaporator 131 will be described. The cleaning wastewater containing the chelating agent discharged from the cleaning wastewater receiving tank 103 (see FIG. 8) and the cleaning wastewater receiving tank 117 (see FIG. 9) is removed from the cleaning wastewater passage 133 except for moisture that naturally evaporates (vaporizes) into the atmosphere. Then, it flows into the cleaning wastewater storage tank 134 and is stored.

  The cleaning wastewater stored in the cleaning wastewater storage tank 134 is supplied to each water supply pipe 161 by the cleaning wastewater supply pump 165 via the cleaning wastewater supply pipe 164 and the intermediate pipe 163, and from each water discharge nozzle 162 to the sand container. It is discharged in the form of drops or mists generally downward toward the upper surface of the sand layer 155 in 135, and is evenly spread on the sand layer 155. In this manner, the washing waste water is sprayed on the sand layer 155 in the sand container 135 by the water discharge nozzle 162, and the washing waste water is always held between the sand particles in the sand layer 155, or the sand particles are thin films of the washing waste water. Is maintained in a saturated moisture state (for example, a water content ratio of 30 to 35%) covered with.

  Then, the cleaning wastewater retained in the sand layer 155 evaporates (vaporizes) into the atmosphere. Thus, all of the cleaning wastewater flowing into the cleaning wastewater storage tank 134 evaporates (vaporizes) from the sand layer 155 into the atmosphere. At that time, the chelating agent contained in the cleaning wastewater remains in the sand layer 155. Therefore, the chelating agent contained in the cleaning wastewater is reliably recovered without being discharged to the outside. The area or size of the sand container 135 required for evaporating the cleaning wastewater from the sand layer 155 will be described later.

  The amount of cleaning wastewater sprayed from the cleaning wastewater spraying device 143 (water discharge nozzle 162) to the sand layer 155 is preferably set to be larger than the amount of cleaning wastewater evaporated from the sand layer 155 (for example, 1. 2 to 2.0 times). Thereby, the water evaporating sand constituting the sand layer 155 is maintained in a saturated moisture state (for example, a water content ratio of 30 to 35%). Here, surplus cleaning wastewater flows down the gaps between the sand particles in the sand layer 155, passes through the perforated plate 154, and flows into the drainage groove 151. Then, the excess cleaning wastewater in the drainage groove 151 returns to the cleaning wastewater storage tank 134 via the collective drainage groove 152.

When such a cleaning wastewater evaporation process is repeatedly performed, the chelating agent is gradually accumulated in the sand layer 155 in the sand container 135. Therefore, every time a predetermined period elapses (for example, every 2 to 6 months), water evaporating sand in a predetermined area or section (for example, an area of 100 to 200 m ² ) in the sand container 135 is removed. Then, it is introduced into the sand washing section 14 and the chelating agent is recovered. Then, fine sand sieved from the sand discharged from the sand rinsing unit 17 is introduced as water evaporating sand into the section or region where the water evaporating sand is removed from the sand containing unit 135. That is, the water evaporating sand containing the chelating agent in a predetermined section or region in the sand container 135 is replaced with fine sand obtained by sieving from the sand not containing the chelating agent. Therefore, the loss of the chelating agent from the soil purification system S to the outside can be prevented or reduced. Further, since a part of the sand that does not contain the chelating agent from the sand rinsing unit 17 is used as the water evaporating sand stored in the sand storing unit 135, the water evaporating sand used in the sand storing unit 135 can be easily procured. Can do.

  Hereinafter, an example of the specifications (surface area, dimensions, etc.) of the cleaning wastewater storage tank 134 and the sand container 135 required for evaporating the cleaning wastewater from the sand layer 155 will be described. For example, the soil remediation system S purifies 100 tons of contaminated soil (including moisture) per hour, and this contaminated soil includes 25 tons of gravel (dry basis), 30 tons of sand (dry basis), It shall contain 25 tons of soil (dry basis) and 20 tons of water (water content 25%). And when this soil purification system S is operated for 250 days a year using 8 hours a day, the specifications of the washing waste water storage tank 134 and the sand container 135 can be set as follows, for example. In addition, the specification demonstrated here is an example to the last, and even when the amount of soil treatment of soil treatment system S, or operation time or operation days differ from these, it is the same method of washing waste water storage tank 134 and sand storage part 135. Of course, specifications or dimensions can be set.

<Specifications of cleaning wastewater storage tank 134>
The specification of the washing waste water storage tank 134 is set as follows, for example.
・ Cuboid storage tank (left and right dimensions: 20m, front and rear dimensions: 30m, depth: 3m)
・ Surface area 600m ²
・ Maximum water storage capacity: about 1600 tons

<Specifications of sand container 135>
The specification of the sand accommodating part 135 is set as follows, for example.
・ Cuboid (left and right dimensions: 50m, front and rear dimensions: 160m, depth: 0.8m)
・ Top surface area 8000m ²
・ Sand capacity approximately 4000m ³

<Discharge of washing wastewater from the sand rinse section 17>
The amount of chelate cleaning liquid contained in the sand (30 tons / hr on a dry basis) discharged from the vacuum suction belt conveyor 23 of the sand cleaning section 14 is 10%, and the amount of rinse water used in the sand rinse section 17 is included in the sand. If it is set to 2.0 times the amount of the chelate cleaning liquid that is deposited or adhered, the discharge amount of the cleaning wastewater containing the chelating agent from the sand rinse portion 17 becomes 12000 tons / year.
30 tons / hr x 0.1 x 8 hr x 250 days x 2.0 = 12,000 tons / year

<Discharge of washing wastewater from soil rinse section 18>
The chelate cleaning solution content ratio of the soil discharged from the soil cleaning unit 15 (25 tons / hr on a dry basis) is 20%, and the amount of rinsing water used in the soil rinsing unit 18 is included in or attached to the soil. If it is 1.2 times the cleaning liquid, the discharge amount of the cleaning wastewater containing the chelating agent from the soil rinsing section 18 will be 12,000 tons / year.
25 tons / hr x 0.2 x 8 hr x 250 days x 1.2 = 12,000 tons / year

<Water evaporation in washing waste water storage tank 134>
In general, it is known that the evaporation amount of water from the water surface in lakes and reservoirs is 0.5 to 1.0 ton per 1 m ^{2 of} water surface. Therefore, it is estimated that at least 300 tons of water evaporates annually from the cleaning wastewater storage tank 134 (surface area 600 m ² ).
0.5 tons / m ² · year × 600 m ² = 300 tons / year As described above, the maximum water storage capacity of the washing waste water storage tank 134 is about 1600 tons. This corresponds to approximately 16 days of discharge of washing wastewater (24000 tons / year, that is, 96 tons / day after 250 days of operation). On the other hand, since the cleaning wastewater stored in the cleaning wastewater storage tank 134 is processed in the sand storage unit 135 every day, the cleaning wastewater storage tank 134 can store the cleaning wastewater with sufficient margin without overflowing. it can.

<Water evaporation in sand layer 155>
For example, in view of the disclosure content (research results) of Non-Patent Document 1, the amount of water evaporation in the sand layer 155 in the sand container 135 is 3.15 tons / m ² · year as described below. Estimated. That is, in Non-Patent Document 1, the water content ratio is 32.1% (saturated moisture state) when the temperature is 14.2 ° C., the relative humidity is 59%, and the air flow rate is 250 cm / second. The evaporation rate of water from the soil is disclosed as 11.3 × 10 ⁻⁶ g / cm ² · sec. In addition, when the temperature is 14.8 ° C., the relative humidity is 57%, and the air flow rate is 170 cm / sec, the water content is evaporated from the soil having a water content ratio of 32.9% (saturated moisture state). The speed is disclosed to be 7.9 × 10 ⁻⁶ g / cm ² · sec.

In view of such disclosure of Non-Patent Document 1, when the average climatic state in Japan is assumed to be a temperature of 15 ° C., a relative humidity of 60%, and a wind speed of about 2 m / second, saturated moisture in the sand container 135 is assumed. The average water evaporation from the sand layer 155 in the state is estimated to be approximately 10.0 × 10 ⁻⁶ g / cm ² · sec. The amount of evaporation is 3.15 ton / m ² · year when converted to a practical unit.
10.0 × 10 ⁻⁶ g / cm ² · sec = 10.0 × 10 ⁻⁶ × 10 ⁻⁶ × 10 ⁴ tons / m ² · sec = 1.0 × 10 ⁻⁷ tons / m ² · sec = 1 0.0 × 10 ⁻⁷ × 3600 × 24 × 365 tons / m ² · year = 3.15 tons / m ² · year Therefore, from the sand layer 155 (8000 m ² ) in the sand containing portion 135, 25200 tons of water per year Evaporate.
3.15 tons / m ² · year x 8000 m ² = 25200 tons / year

<Balance of water in washing waste water evaporator 131>
As described above, the discharge amount of the cleaning wastewater from the sand rinse part 17 is estimated to be 12,000 tons per year. In addition, the amount of cleaning wastewater discharged from the soil rinse section 18 is estimated to be 12,000 tons per year. On the other hand, at least 300 tons of water can be evaporated per year in the washing wastewater storage tank 134 and 25200 tons of water can be evaporated per year in the sand container 135. Therefore, it is estimated that the cleaning wastewater evaporator 131 can evaporate 25,500 tons of water annually. As described above, the cleaning waste water evaporator 131 evaporates a larger amount of cleaning waste water than the amount of cleaning waste water discharged from the sand rinsing unit 17 and the soil rinsing unit 18 (24,000 tons per year) in one year. Therefore, basically, all of the cleaning waste water can be evaporated and treated. However, since the evaporation amount of the washing wastewater decreases, for example, in the winter season or the rainy season, the size (160 m) in the front-rear direction or the dimension (50 m) in the left-right direction of the sand container 135 in the above specific example is 10-20. It is preferable to make it about% longer.

  As described above, according to the contaminated soil purification system S or the contaminated soil purification method according to the present invention, a chelating agent is not added to a large amount of washing water circulating through a series of distribution systems in the soil purification system S, and discharged from the liquid cyclone 7. Since the sand discharged from the filter press 13 and the soil discharged from the filter press 13 are washed with the chelate washing liquid, the amount of the chelating agent retained in the soil purification system S can be greatly reduced. And since the sand and soil washed with the chelate washing liquid are washed with rinsing water in the sand rinsing part 17 and the soil rinsing part 18, respectively, sand and earth suitable for reuse not containing a chelating agent can be obtained. . Moreover, since the chelating agent in the cleaning wastewater discharged from the sand rinsing unit 17 and the soil rinsing unit 18 is returned to the sand cleaning unit 14 by the chelating agent recovery unit 19, the amount of chelating agent used can be greatly reduced. it can. Further, since the content of the chelate cleaning liquid in the sand wet with the chelate cleaning liquid is reduced by vacuum suction with the vacuum suction belt conveyor 23, the amount of rinse water used in the sand rinse section 17, that is, the amount of cleaning waste water to be evaporated is set. It can reduce, and the site area of the sand accommodating part 135 can be reduced.

  S soil purification system, 1 soil classification unit, 2 sand / soil purification unit, 3 input hopper, 4 mixer, 5 mil breaker, 6 trommel, 7 liquid cyclone, 8 PH adjustment tank, 9 coagulation tank, 10 thickener, 11 washing Water storage tank, 12 Intermediate tank, 13 Filter press, 14 Sand cleaning section, 15 Soil cleaning section, 16 Chelating agent regeneration section, 17 Sand rinsing section, 18 Soil rinsing section, 19 Chelating agent recovery section, 21 Mixing stirrer, 22 Vibration Sieve, 23 Vacuum suction belt conveyor, 25 Main body, 26 Baffle plate, 27 Stirrer, 28 Motor, 30 Wire net, 31 Casing, 32 Pipe line, 33 Cleaning liquid storage tank, 34 1st roller, 35 2nd roller, 36 Filter media installed Belt, 37 Decompression chamber, 38 Exhaust pipe, 39 Drain pipe, 40 Scraper, 41 Crusher, 42 Premix tank, 43 Mixer, 44 chelate cleaning liquid storage tank, 45 pump, 46 pipe, 47 stirrer, 48 pump, 49 pipe, 50 storage tank, 51-54 partition wall, 55-59 water channel, 61-65 air discharge pipe, 71 packed tower, 72 Intermediate storage tank, 73 Regenerated chelate cleaning liquid storage tank, 74 Acid liquid storage tank, 75 Water storage tank, 76 pump, 77-80 pipe, 81 pump, 82 pipe, 83 pump 84 pipe, 85 pipe, 86 pump, 87 pipe , 88 pipe line, 91-98 valve, 100 belt conveyor, 101 sand supply device, 102 rinse water spray device, 103 washing waste water receiving tank, 104 drive roller, 104a shaft, 105 driven roller, 105a shaft, 106 transport belt, 107 support Roller, 108 Guide plate, 110 Soil crusher, 111 Soil rinsing device, 11 Blade, 114 Belt conveyor, 115 Soil supply device, 116 Rinse water spray device, 117 Washing waste water receiving tank, 118 Drive roller, 118a shaft, 119 Driven roller, 119a shaft, 120 Conveyor belt, 121 Support roller, 122 Guide plate, 131 Washing Waste water evaporation device, 133 Washing waste water passage, 134 Washing waste water storage tank, 135 Sand container, 136 Front end wall, 137 Rear end wall, 138 Left side wall, 139 Right side wall, 140 Bottom wall, 142 Roof, 143 Washing waste water spraying device, 144 Washing wastewater recirculation mechanism, 150 ground, 151 drainage groove, 152 collecting drainage groove, 153 convex portion, 154 perforated plate, 155 sand layer, 157 left vertical frame, 158 right vertical frame, 159 horizontal frame, 161 water supply pipe, 162 water discharge nozzle, 163 Medium Pipe, 164 cleaning waste water supply pipe, 165 cleaning waste supply pump.

Claims (3)

A soil purification system that purifies soil contaminated with harmful metals or compounds thereof including gravel, sand and soil,
The soil purification system is configured to wash a soil classification unit that classifies the soil into gravel, sand, and soil, and sand and soil separated by the soil classification unit with a common chelating cleaning solution containing a chelating agent and water. And have a sand and soil purification section to purify
The soil classification part is
A mixing device for mixing the soil put into the soil classifying unit and washing water;
Trommel that separates gravel from a mixture of soil and wash water discharged from the mixing device;
A liquid cyclone for separating sand from a mixture of sand, soil and wash water discharged from the trommel;
A thickener that separates a mixture of soil and washing water discharged from the hydrocyclone into supernatant water and sludge containing soil by sedimentation separation;
A filter press that separates soil by filtering sludge discharged from the thickener;
The sand and soil purification unit
A sand washing unit for washing sand discharged from the hydrocyclone with a chelate washing solution and removing harmful metals or compounds thereof from the sand;
Cleaning the soil discharged from the filter press with a chelate cleaning solution, and removing a toxic metal or a compound thereof from the soil;
The sand washing unit and to remove toxic metals or their compounds from chelating agent chelates in the cleaning liquid discharged from the soil cleaning unit reproduces the chelating agent, is returned to the sand cleaning unit and the soil washing unit, the sand A chelating agent regeneration unit common to the cleaning unit and the soil cleaning unit ;
A sand rinsing part for removing the chelating agent by washing the sand discharged from the sand washing part with rinsing water;
A soil rinsing section for removing the chelating agent by rinsing the soil discharged from the soil washing section with rinsing water;
A chelating agent recovery unit for recovering a chelating agent from washing waste water containing a chelating agent discharged from the sand rinsing unit and the soil rinsing unit, and a chelating agent recovery unit common to the sand rinsing unit and the soil rinsing unit ,
The sand washing part
Mixing and stirring the sand discharged from the liquid cyclone and the chelate cleaning liquid, stirring, and a flow-type mixing stirrer that captures the harmful metal adhering to or binding to the sand or a compound thereof in the chelating agent;
A vibrating sieve for removing the chelate cleaning liquid from the mixture of sand and chelate cleaning liquid discharged from the mixing stirrer;
The sand wet with the chelating cleaning liquid discharged from the vibrating sieve is received, and the sand is vacuum sucked through the filter medium mounting belt while the sand is transported by the filter medium mounting belt to reduce the content of the chelate cleaning liquid in the sand. A vacuum suction belt conveyor
The soil washing part
A mixing and dispersing device for mixing the soil discharged from the filter press and the chelate cleaning liquid, and generating a soil dispersion slurry in which the soil is dispersed in the chelate cleaning liquid;
The soil dispersion slurry produced by the mixing and dispersing device is allowed to flow through a plug flow so as to ensure a preset residence time while stirring, thereby removing harmful metals or compounds thereof adhering to the soil from the soil. A soil cleaning device that captures the chelating agent,
A filtration device for filtering the soil dispersion slurry discharged from the soil cleaning device,
The chelating agent regenerating unit has a complexing power higher than that of the chelating agent when the chelating cleaning solution discharged from the sand cleaning unit and the filtration device is brought into contact with the chelating cleaning solution. It has a solid phase adsorbent that adsorbs, has a chelate cleaning liquid regenerating device that regenerates the chelating cleaning liquid by removing harmful metals or their compounds from the chelating agent in the chelating cleaning liquid,
The sand rinsing unit receives the sand discharged from the sand washing unit, and sprays or sprays rinsing water on the sand while transporting the sand with a filter medium mounting belt, and thereby a chelating agent held in the sand is obtained. Vacuum suction type that reduces the amount of rinsing water by evacuating the sand through the filter media mounting belt while promoting removal of the rinsing water by air flowing through the gap between the sand particles A sand rinsing device with a belt conveyor ;
The soil rinsing unit receives the soil discharged from the filtration device, and sprays or sprays rinsing water on the soil while transporting the soil with a filter medium mounting belt, thereby removing the chelating agent held in the soil. On the other hand, vacuum suction belt that reduces the amount of rinse water used by vacuum suction of the soil through the filter medium mounting belt and promoting downward movement of rinse water with air flowing through the voids between the soil particles Having a soil rinsing device with a conveyor ,
The chelating agent recovery unit
A cleaning wastewater storage tank that receives and stores cleaning wastewater containing a chelating agent discharged from the sand rinse portion and the soil rinse portion,
A container-shaped sand container that is disposed on the ground and accommodates water evaporating sand, the upper side being opened;
A roof disposed above the sand container and preventing rain water from dropping into the sand container;
A cleaning wastewater spraying device for spraying the cleaning wastewater stored in the cleaning wastewater storage tank to the water evaporation sand stored in the sand storage unit,
A washing waste water recirculation mechanism that recirculates excess washing waste water flowing down through the gaps between the particles of water evaporating sand contained in the sand containing portion to the washing waste water storage tank;
The soil purification system further includes a cleaning wastewater sprayed from the cleaning wastewater spraying device over a predetermined period on the water evaporation sand stored in the sand container, and the water of the cleaning wastewater sprayed on the water evaporation sand. When the water evaporates in the air and the chelating agent is accumulated in the water evaporating sand, the water evaporating sand is transferred to the sand cleaning unit. Means,
A soil purification system comprising water evaporating sand supply means for supplying a part of sand discharged from the sand rinsing unit to the sand container as water evaporating sand. A soil purification method in a soil purification facility for purifying soil contaminated with harmful metals or compounds thereof including gravel, sand and soil,
The soil purification facility is configured to wash a soil classification unit that classifies the soil into gravel, sand, and soil, and sand and soil separated by the soil classification unit with a common chelating cleaning solution containing a chelating agent and water. And have a sand and soil purification section to purify
The soil classification part is
A mixing device for mixing the soil put into the soil classifying unit and washing water;
Trommel that separates gravel from a mixture of soil and wash water discharged from the mixing device;
A liquid cyclone for separating sand from a mixture of sand, soil and wash water discharged from the trommel;
A thickener that separates a mixture of soil and washing water discharged from the hydrocyclone into supernatant water and sludge containing soil by sedimentation separation;
A filter press that separates soil by filtering sludge discharged from the thickener;
The sand and soil purification unit
A sand washing unit for washing sand discharged from the hydrocyclone with a chelate washing solution and removing harmful metals or compounds thereof from the sand;
Cleaning the soil discharged from the filter press with a chelate cleaning solution, and removing a toxic metal or a compound thereof from the soil;
The sand washing unit and to remove toxic metals or their compounds from chelating agents chelate in the washing liquid discharged from the soil cleaning unit plays a chelating agent, sends back to the sand cleaning unit and the soil washing unit, the sand A chelating agent regeneration unit common to the cleaning unit and the soil cleaning unit ;
A sand rinsing part for removing the chelating agent by washing the sand discharged from the sand washing part with rinsing water;
A soil rinsing section for removing the chelating agent by washing the soil discharged from the soil washing section with rinsing water;
A chelating agent recovery unit for recovering a chelating agent from washing waste water containing a chelating agent discharged from the sand rinsing unit and the soil rinsing unit, and a chelating agent recovery unit common to the sand rinsing unit and the soil rinsing unit ,
The sand washing part
Mixing and stirring the sand discharged from the liquid cyclone and the chelate cleaning liquid, stirring, and a flow-type mixing stirrer that captures the harmful metal adhering to or binding to the sand or a compound thereof in the chelating agent;
A vibrating sieve for removing the chelate cleaning liquid from the mixture of sand and chelate cleaning liquid discharged from the mixing stirrer;
The sand wet with the chelating cleaning liquid discharged from the vibrating sieve is received, and the sand is vacuum sucked through the filter medium mounting belt while the sand is transported by the filter medium mounting belt to reduce the content of the chelate cleaning liquid in the sand. A vacuum suction belt conveyor
The soil washing part
A mixing and dispersing device for mixing the soil discharged from the filter press and the chelate cleaning liquid, and generating a soil dispersion slurry in which the soil is dispersed in the chelate cleaning liquid;
The soil dispersion slurry produced by the mixing and dispersing device is allowed to flow through a plug flow so as to ensure a preset residence time while stirring, thereby removing harmful metals or compounds thereof adhering to the soil from the soil. A soil cleaning device that captures the chelating agent,
A filtration device for filtering the soil dispersion slurry discharged from the soil cleaning device,
The chelating agent regenerating unit has a complexing power higher than that of the chelating agent when the chelating cleaning solution discharged from the sand cleaning unit and the filtration device is brought into contact with the chelating cleaning solution. It has a solid phase adsorbent that adsorbs, has a chelate cleaning liquid regenerating device that regenerates the chelating cleaning liquid by removing harmful metals or their compounds from the chelating agent in the chelating cleaning liquid,
The sand rinsing unit accepts the sand discharged from the sand washing unit, by dispersing or injecting a rinse water into the sand while conveying the sand in the filter medium fitting belt, a chelating agent held in the sand Vacuum suction type that reduces the amount of rinsing water by evacuating the sand through the filter media mounting belt while promoting removal of the rinsing water by air flowing through the gap between the sand particles A sand rinsing device with a belt conveyor ;
The soil rinsing unit receives the soil discharged from the filtration device, and sprays or sprays rinsing water on the soil while transporting the soil with a filter medium mounting belt, thereby removing the chelating agent held in the soil. On the other hand, vacuum suction belt that reduces the amount of rinse water used by vacuum suction of the soil through the filter medium mounting belt and promoting downward movement of rinse water with air flowing through the voids between the soil particles Having a soil rinsing device with a conveyor ,
The chelating agent recovery unit
A cleaning wastewater storage tank that receives and stores cleaning wastewater containing a chelating agent discharged from the sand rinse portion and the soil rinse portion,
A container-shaped sand container that is disposed on the ground and accommodates water evaporating sand, the upper side being opened;
A roof disposed above the sand container and preventing rain water from dropping into the sand container;
A cleaning wastewater spraying device for spraying the cleaning wastewater stored in the cleaning wastewater storage tank to the water evaporation sand stored in the sand storage unit,
A washing waste water recirculation mechanism that recirculates excess washing waste water flowing down through the gaps between the particles of water evaporating sand contained in the sand containing portion to the washing waste water storage tank;
The soil purification method includes:
While spraying the cleaning wastewater from the cleaning wastewater spraying device on the water evaporation sand stored in the sand storage unit, the water of the cleaning wastewater adhering to the water evaporation sand is evaporated into the air. Removing from the sand container,
Introducing the water evaporating sand in which the chelating agent is accumulated for a predetermined period in the sand containing unit into the sand washing unit, and recovering the chelating agent accumulated in the water evaporating sand;
A method for soil purification, wherein a part of the sand discharged from the sand rinsing part is used as sand for water evaporation contained in the sand container.   The water evaporating sand is fine sand, and the water content of the water evaporating sand accommodated in the sand accommodating portion is set to 30 to 35 in terms of the amount of washing waste water sprayed from the washing waste water dispersing device to the sand accommodating portion. The soil purification method according to claim 2, wherein the soil purification method is set to be maintained at%.

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