JP5771343B1 - Contaminated soil purification equipment - Google Patents

Abstract

Provided is a practical contaminated soil purification apparatus that makes it possible to purify a large amount of hazardous metal-contaminated soil as well as hazardous metal-contaminated soil containing harmful substances other than hazardous metals as a business. A contaminated soil purification apparatus S includes a crushing part 1, a classifying part 2, a sedimentation separating part 3, a filtering part 4, and a chelating agent regenerating part 5. The crushing unit 1 crushes stones and / or gravel mixed in soil contaminated with harmful metals. The classifying unit 2 mixes the soil discharged from the crushing unit 1 with washing water containing a chelating agent, separates harmful metals from the soil and captures them in the chelating agent, and separates coarse aggregate and sand from the soil. And collect. The sedimentation separation unit 3 separates the wash water containing fine-grained soil discharged from the classification unit 2 into supernatant water and sludge containing fine-grained soil by sedimentation separation. The chelating agent regeneration unit 5 regenerates the chelating agent by removing harmful metals or the like captured by the chelating agent in the supernatant water discharged from the sedimentation separation unit 4. [Selection] Figure 1

Description

  The present invention relates to a contaminated soil purification apparatus for purifying a large amount of contaminated soil contaminated with harmful metals and / or compounds thereof or other contaminants.

  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, soil contaminated with toxic metals (hereinafter referred to as “toxic metal-contaminated soil”) is insolubilized, for example, with toxic metals at the location where the toxic metal-contaminated soil actually exists (hereinafter referred to as “original location”). Effective purification, such as by containment or electrical repair, is quite difficult. For this reason, toxic metal-contaminated soil is generally removed from the original position by excavation and purified by an external soil purification device. It should be noted that the site where the toxic metal-contaminated soil has been removed is usually backfilled with the original soil purified by the soil purification device or another clean soil.

  Conventionally known methods for purifying toxic metal-contaminated soil with an off-site soil purification device include melting treatment (see, for example, Patent Literature 1) and soil cleaning treatment (see, for example, Patent Literatures 2 and 3). Yes. Here, the melting treatment is a soil purification method in which harmful metals contaminated soil is melted and then rapidly cooled to contain harmful metals and the like, and the soil is used as an aggregate. This is a problem that it is not suitable for treating a large amount of toxic metal-contaminated soil.

  On the other hand, soil washing treatment is a soil purification method that removes harmful metals, etc. by washing hazardous metal-contaminated soil, and hardly requires thermal energy. Is suitable. Therefore, the inventors of the present application already disclosed in Patent Document 4 as a method for purifying toxic metal-contaminated soil by soil cleaning treatment, from contamination by cleaning contaminants contaminated with toxic metals with a chelating agent-containing cleaning solution. By removing toxic metals, etc., contacting the cleaning waste liquid generated by this cleaning with a solid-phase adsorbent having a higher complexing ability than the chelating agent, and removing and recovering toxic metals from the chelating agent-containing cleaning liquid A method for purifying toxic metal contaminants by regenerating an agent-containing cleaning solution has been proposed (see paragraph [0006] of Patent Document 4).

  According to the method for purifying hazardous metal contaminants according to the invention described in Patent Document 4, solid-phase adsorption from a cleaning waste liquid after cleaning contaminated soil contaminated with hazardous metals with a cleaning agent containing a chelating agent Since harmful metals and the like are removed with the material, a cleaning solution or a chelating agent can be used repeatedly, and a contaminated soil purification system with very low energy consumption can be constructed. As a result, it becomes easy to purify naturally contaminated soil and other contaminated soil, and it is expected that the contaminated waste is expected to be reduced in volume and effectively used (paragraph [4] in Patent Document 4). 0010]).

JP 2000-246232 A JP 2000-325936 A JP 2007-098299 A Patent No. 5164169 specification

  As described above, the invention described in Patent Document 4 constructs a purification system capable of purifying toxic metal-contaminated soil while repeatedly using a cleaning solution containing a chelating agent without consuming almost any heat energy. Is possible. However, Patent Document 4 discloses a laboratory-scale example, but has not yet proposed a specific contaminated soil purification apparatus for actually purifying a large amount of harmful metal-contaminated soil as a business. Therefore, the present invention utilizes a laboratory-scale toxic metal contaminant purification method according to the invention described in Patent Document 4, and a large amount of toxic metal-contaminated soil, as well as predetermined contaminants other than toxic metals, etc. It is a problem to be solved to provide a practical contaminated soil purification device that makes it possible to actually purify toxic metal-contaminated soil including water as a business.

  The contaminated soil purification apparatus according to the present invention made to solve the above problems includes a crushing section, a classification section, a sedimentation separation section, and a chelating agent regeneration section. In this contaminated soil purification apparatus, the crushing section accepts soil contaminated with toxic metals and the like (toxic metals and / or compounds thereof) containing stones and / or gravel, Or crush the gravel. The classification unit mixes the soil discharged from the crushing unit and washing water containing a chelating agent, and removes harmful metals adhering to the soil from the soil and captures them in the chelating agent. The material (stone and / or gravel) and sand are separated and removed (recovered). The sedimentation separation unit separates wash water containing fine-grained soil (silt and / or clay) discharged from the classification unit into supernatant water and sludge containing fine-grained soil by sedimentation separation. The chelating agent regeneration unit receives the supernatant water discharged from the sedimentation separation unit and removes the harmful metals etc. or these ions from the chelating agent capturing the ions in the supernatant water. Play.

  In the contaminated soil purification apparatus according to the present invention, the chelating agent regeneration unit includes a washing water regeneration device, a washing water separation screen, a washing water reflux mechanism, a solid phase adsorbent regeneration mechanism, and a solid phase adsorbent particle return mechanism. It has. The washing water regenerating apparatus includes a solid-phase adsorbent that adsorbs harmful metals, etc. in these supernatant water or these ions when it comes into contact with the supernatant water having higher complexing power than the chelating agent and discharged from the sedimentation separation unit. The solid phase adsorbent particles and the supernatant water discharged from the sedimentation separation unit are mixed and stirred, and harmful metals are removed from the chelating agent in the supernatant water to regenerate the supernatant water as washing water. The cleaning water separation screen separates the cleaning water from the mixture of the solid-phase adsorbent particles and the cleaning water discharged from the cleaning water regenerator. The washing water reflux mechanism refluxs the washing water discharged from the washing water separation screen to the classification unit. In addition to the classification unit, the washing water may be supplied (refluxed) to the crushing unit.

  The solid-phase adsorbent regeneration mechanism mixes the solid-phase adsorbent particles discharged from the washing water separation screen with an acid solution, removes harmful metals adsorbed on the solid-phase adsorbent particles with the acid solution, and removes the solid phase adsorbent particles. Regenerate the adsorbent particles. The solid-phase adsorbent particle return mechanism returns the solid-phase adsorbent particles discharged from the washing water separation screen or the solid-phase adsorbent particles regenerated by the solid-phase adsorbent regeneration mechanism to the washing water regenerator. Here, the solid-phase adsorbent has a multipoint interaction by coordination bonds and hydrogen bonds in which a cyclic molecule is supported on a carrier and a chelate ligand is modified on the cyclic molecule, and harmful metals, etc. Selective capture.

  In the contaminated soil purification apparatus according to the present invention, the washing water regenerating apparatus is formed by mixing the solid phase adsorbent particles and the washing water into the inlet portion, and the solid phase adsorbent particles and the washing water flowing in from the inlet portion. A flow-through reactor including a cylindrical main body for flowing the mixture in the longitudinal direction, a stirrer for stirring the mixture in the main body, and an outlet for discharging the mixture from the main body is preferable.

  Further, the solid-phase adsorbent regeneration mechanism includes an acid liquid cleaning device that mixes the solid-phase adsorbent particles discharged from the washing water separation screen with an acid solution, and cleans and recovers the solid-phase adsorbent particles with the acid solution, The acid liquid separation screen for separating the acid liquid from the mixture of the solid phase adsorbent particles discharged from the acid liquid cleaning apparatus and the acid liquid, and the solid phase adsorbent particles discharged from the acid liquid separation screen are mixed with rinse water, It is preferable to have a water washing apparatus for washing the solid phase adsorbent particles and a water separation screen for separating the rinse water from the mixture of the solid phase adsorbent particles and the rinse water discharged from the water washing apparatus. Here, the solid-phase adsorbent particle returning mechanism preferably returns the solid-phase adsorbent particles discharged from the washing water separation screen or the solid-phase adsorbent particles discharged from the water separation screen to the washing water regenerating apparatus.

  In the contaminated soil purification apparatus according to the present invention, the crushing unit is configured to mix the soil contaminated with harmful metals and the like and the cleaning water supplied from the cleaning water reflux mechanism, and the soil discharged from the mixing apparatus and the cleaning It preferably has a wet mill breaker that accepts a mixture of water and crushes stones or gravel contained in the soil. The classifying unit mixes the soil discharged from the mill breaker and the washing water supplied from the washing water reflux mechanism, and separates and removes (recovers) the coarse aggregate from the soil, and discharges from the trommel. It preferably has a sand separation mechanism equipped with a cyclone and a sand screen that receives the mixture of the soil and washing water and separates (recovers) the sand from the mixture.

  The contaminated soil purification apparatus according to the present invention preferably includes a filtration unit that filters sludge discharged from the sedimentation separation unit to produce a filter cake, such as a vacuum filter, a filter press, and the like. In this case, it is more preferable that the contaminated soil purification device includes a continuous drying device for drying the filter cake discharged from the filtration unit, for example, an aeration band dryer or an aeration rotary dryer.

  According to the present invention, since the soil discharged from the crushing part is washed with the washing water containing the chelating agent in the classification part, coarse aggregate (stone and / or gravel), sand, fine-grained soil contained in the soil Toxic metals adhering to etc. are removed. For this reason, the fine aggregate contained in the coarse aggregate or sand separated and recovered in the classification part or the sludge discharged from the sedimentation part hardly contains harmful metals and the like. Therefore, coarse aggregate or sand can be used as civil engineering / building materials, and sludge can be used for plant cultivation or the like as improved soil by dehydrating by filtration or the like. Therefore, it is possible to generate coarse aggregate, sand (washed sand) and / or fine-grained soil (improved soil) that can be reused with almost no harmful metals, etc., from soil contaminated with harmful metals. . Certain chelating agents can also capture specific pollutants (eg, boron, fluorine, etc.) other than toxic metals (eg, “9000 Series Chelating Agent for Wastewater” by Honmachi Chemical Industry Co., Ltd.) .

  The washing water containing the chelating agent is used in a circulating manner, and harmful metals captured by the chelating agent are removed by the solid phase adsorbent in the middle of the circulation, and are appropriately adsorbed by the solid phase adsorbent. Harmful metals and the like are removed by the acid solution. For this reason, it is necessary to continuously purify a large amount of soil contaminated with harmful metals, etc. with almost no replenishment of chelating agents or solid-phase adsorbents, and clean aggregates or coarse aggregates, washing sand, improved soils, etc. Can be generated.

It is a block diagram which shows the schematic structure of the contaminated soil purification apparatus which concerns on this invention. It is a block diagram which shows the specific structure of the contaminated soil purification apparatus which concerns on this invention. It is a schematic diagram which shows the specific structure of the chelating agent reproduction | regeneration part of the contaminated soil purification apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, a schematic configuration of a contaminated soil purification apparatus according to the present invention will be described with reference to FIG. As shown in FIG. 1, the contaminated soil purification apparatus S according to the present invention includes a crushing unit 1, a classification unit 2, a sedimentation separation unit 3, a filtration unit 4, and a chelating agent regeneration unit 5.

  In this contaminated soil purification apparatus S, the crushing unit 1 accepts soil containing stones and / or gravel and contaminated with harmful metals or the like (toxic metals and / or compounds thereof) and is mixed in the soil. Crush stones and / or gravel; The classifying unit 2 mixes the soil discharged from the crushing unit 1 and washing water containing a chelating agent, separates harmful metals attached to the soil from the soil, and captures the chelating agent. Separate and collect coarse aggregate and sand from the soil. The sedimentation / separation unit 3 separates the wash water containing fine-grained soil (silt and / or clay) discharged from the classification unit 2 into supernatant water and sludge containing fine-grained soil by sedimentation separation. The filtration unit 4 filters the sludge discharged from the sedimentation separation unit 3 to generate a filter cake. The chelating agent regeneration unit 5 receives the supernatant water discharged from the sedimentation separation unit 3 and removes harmful metals and the like captured by the chelating agent in the supernatant water or regenerates the chelating agent.

  In this contaminated soil purification apparatus S, the chelating agent regeneration unit 5 is not shown in FIG. 1, but includes a washing water regeneration apparatus, a washing water separation screen, a washing water reflux mechanism, and a solid phase adsorbent regeneration mechanism. And a solid-phase adsorbent particle returning mechanism (see FIG. 2). The washing water regenerator includes a solid-phase adsorbent that adsorbs harmful metals, etc. in the supernatant water or these ions when coming into contact with the supernatant water having a higher complexing power than the chelating agent and discharged from the sedimentation separation unit 3. The solid phase adsorbent particles and the supernatant water discharged from the sedimentation separation unit 3 are mixed and stirred, and harmful metals and the like are removed from the chelating agent in the supernatant water to regenerate the supernatant water as washing water.

  The cleaning water separation screen separates the cleaning water from the mixture of the solid-phase adsorbent particles and the cleaning water discharged from the cleaning water regenerator. The washing water reflux mechanism causes the washing water discharged from the washing water separation screen to be refluxed to the classification unit 2. The washing water reflux mechanism may be configured to supply washing water to the crushing unit 1 in addition to the classification unit 2.

  The solid-phase adsorbent regeneration mechanism mixes the solid-phase adsorbent particles discharged from the washing water separation screen with an acid solution, removes harmful metals adsorbed on the solid-phase adsorbent particles with the acid solution, and removes the solid phase adsorbent particles. Regenerate the adsorbent particles. More specifically, the solid-phase adsorbent regeneration mechanism is an acid solution in which the solid-phase adsorbent particles discharged from the washing water separation screen are mixed with an acid solution, and the solid-phase adsorbent particles are washed with the acid solution and regenerated. Washing device, acid solution separation screen for separating acid solution from mixture of solid phase adsorbent particles and acid solution discharged from acid solution cleaning device, and solid phase adsorbent particles discharged from acid solution separation screen to rinse water And a water washing device for washing the solid-phase adsorbent particles with water, and a water separation screen for separating the rinse water from the mixture of solid-phase adsorbent particles and rinse water discharged from the water washing device.

  The solid-phase adsorbent particle return mechanism returns the solid-phase adsorbent particles discharged from the washing water separation screen or the solid-phase adsorbent particles regenerated by the solid-phase adsorbent regeneration mechanism to the washing water regenerator. More specifically, the solid-phase adsorbent particle return mechanism returns the solid-phase adsorbent particles discharged from the washing water separation screen and / or the solid-phase adsorbent particles discharged from the water separation screen to the washing water regeneration device. To do. Here, the solid-phase adsorbent has a multipoint interaction by coordination bonds and hydrogen bonds in which a cyclic molecule is supported on a carrier and a chelate ligand is modified on the cyclic molecule, and harmful metals, etc. Selective capture.

  In this contaminated soil purification apparatus S, the washing water recycling apparatus is configured to mix an inlet part into which solid-phase adsorbent particles and washing water flow, and a mixture obtained by mixing solid-phase adsorbent particles and washing water that has flowed in from the inlet part. It is a flow reactor that includes a cylindrical main body that flows in the longitudinal direction, a stirrer that stirs the mixture in the main body, and an outlet that discharges the mixture from the main body.

  Next, a specific configuration of the contaminated soil purification apparatus S will be described with reference to FIG. As shown in FIG. 2, in the contaminated soil purification apparatus S, first, it is contaminated with harmful metals or the like (toxic metals and / or compounds thereof), and in some cases other contaminants (for example, fluorine, boron, cyan, etc.). The soil (contaminated soil) collected by excavation of the ground contaminated with the second type specific harmful substance) is received by the input hopper 11. Then, the soil in the charging hopper 11 is first charged into the mixing device 12 and mixed with the cleaning water containing the chelating agent in the mixing device 12. Here, the soil is fine-grained soil (silt or clay having a particle size of 0.075 mm or less) and various types of stone or earth and sand such as stone (particle size is 75 mm or more), gravel (particle size is 2 to 75 mm). ) And / or sand (particle size is 0.075 to 2 mm).

  The soil in the input hopper 11 is contaminated with harmful metals or 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. Examples of other contaminants include fluorine or a compound thereof, boron or a compound thereof, and second-type specific harmful substances such as a cyanide compound.

  A mixture of soil and washing water generated by the mixing device 12 (hereinafter referred to as “soil / water mixture”) is transferred to a wet mill breaker 13. As the mill breaker 13, for example, a rod mill can be used. Although not shown in detail, the rod mill is a crushing device in which a plurality of rods (for example, ten 75 mmφ × 2 m steel rods) are arranged in a drum, and the rods rotate parallel to each other by the rotation of the drum. It moves and makes line contact, and crushes stones, gravel, etc. having a relatively large particle size by its impact force, shear force, friction force, and the like. At that time, toxic metals or other contaminants adhering to or contained in stones, gravel, etc. or other pollutants are peeled off or removed and separated into the washing water.

  Thus, toxic metals etc. or other pollutants or their ions that have been detached from the soil surface are captured by the chelating agent in the wash water. Here, the mill breaker 13 is not limited to a rod mill, and other crushing devices such as a ball mill can be used. Note that the mixing device 12 may not be provided, and the soil in the charging hopper 11 may be directly supplied to the mill breaker 13 while the cleaning water containing the chelating agent may be directly supplied to the mill breaker 13.

  Here, as a chelating agent used for washing water, for example, EDTA (ethylenediaminetetraacetic acid), biodegradable HIDS (3-hydroxy-2,2′-iminodisuccinic acid), IDS (2,2′-) Examples thereof include sodium salt of iminodisuccinic acid), MGDA (methylglycine diacetic acid), EDDS (ethylenediaminediacetic acid) or GLDA (L-glutamic acid diacetic acid). Any of these chelating agents can effectively capture (chelate) toxic metals or the like ions adhering to the soil. In addition, when actually treating the soil, a chelating agent suitable for the treatment is selected according to the type of harmful metal or the like contained in the soil, or a plurality of chelating agents are used. The higher the concentration of the chelating agent in the washing water, the higher the trapping amount of harmful metals and the like or these ions, but practically the range of 0.005 to 0.1 mol / liter, preferably 0.01 to 0. It may be set in the range of .05 mol / liter.

  The soil / water mixture discharged from the mill breaker 13 is introduced into the trommel 14. Although not shown in detail, the trommel 14 is a wet sieving device having a receiving tank capable of storing washing 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 (cylindrical central axis) by a motor. Further, the washing water can be sprayed into the drum screen.

  When the soil / water mixture flows through the rotating drum screen of the trommel 14, the soil particles finer than the mesh of the drum screen pass through the mesh of the drum screen together with the wash water, and go out of the drum screen and into the receiving tank. to go into. On the other hand, the soil particles coarser than the mesh of the drum screen cannot pass through the mesh of the drum screen, and are discharged out of the drum screen via the lower open end of the drum screen. In the trommel 14, the soil particles in the soil / water mixture rub against each other, so that toxic metals and other contaminants remaining on or attached to the surface of the soil particles or other contaminants are peeled off and separated into the wash water. In this way, the toxic metals and other contaminants or these ions released in the wash water are captured by the chelating agent in the wash water.

  In this embodiment, the classification diameter (opening) of the drum screen of the trommel 14 is set so that soil particles having a particle diameter of less than 2 mm pass through the mesh of the drum screen. Therefore, in the trommel 14, soil particles (pebbles, stones) having a particle size of 2 mm or more are separated or recovered from the soil / water mixture. Soil particles (pebbles, stones) having a particle size of 2 mm or more contain almost no contaminants. For this reason, soil particles (pebbles, stones) having a particle size of 2 mm or more separated by the trommel 14 can be used, for example, as aggregate or coarse aggregate for concrete, or can be sold.

  Further, such aggregates or coarse aggregates having a particle size of 2 mm or more may be classified using, for example, a sieving device to produce a plurality of types of aggregates or coarse aggregates having different particle sizes. For example, you may classify | categorize into the comparatively fine aggregate whose particle size is less than 5 mm, and the comparatively coarse coarse aggregate whose particle size is 5 mm or more. Note that the mesh size (opening) of the drum screen of the trommel 14 is not limited to that described above, and is arbitrarily set according to the particle size of the relatively large soil particles to be obtained. Of course you can.

  A soil / water mixture containing soil particles having a particle size of less than 2 mm and wash water contained in a receiving tank of the trommel 14 is introduced into the cyclone 15. Although not shown in detail, the cyclone 15 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, The soil / water mixture is separated into a mixture of fine soil having a relatively small particle size (for example, less than 0.075 mm) and washing water, and soil particles having a relatively large particle size (for example, 0.075 mm or more). A mixture of fine-grained soil and washing water (hereinafter referred to as “fine-grained soil-containing water”) is discharged from the upper end portion of the cyclone 15, and soil particles having a relatively large particle size are discharged from the lower end portion of the cyclone 15. . Here, the fine-grained soil-containing water is temporarily stored in the seal tank 16 (intermediate storage tank). The fine-grained soil contained in the fine-grained soil-containing water is, for example, silt or clay having a particle diameter of less than 0.075 mm.

  On the other hand, the relatively large soil particles discharged from the lower end of the cyclone 15 are introduced into the sand screen 17. The soil particles having a relatively large particle diameter are, for example, sand having a particle diameter of 0.075 to 2 mm. The sand screen 17 causes the washing water to flow at a predetermined pressure and amount of water, rinses the soil particles having a relatively large particle size, that is, sand, and collects and removes remaining floating matters or foreign matters. To do. The suspended matter or foreign matter collected by the sand screen 17 is reused as fuel if it is combustible (thermal recycling). Further, soil particles having a relatively large particle size, that is, sand (washed sand) that has been subjected to the rinsing treatment, contain almost no contaminants, and are used or sold as reclaimed sand. The wash water discharged from the sand screen 17 is temporarily stored in the feed tank 18 (intermediate storage tank).

  The fine soil-containing water temporarily stored in the seal tank 16 is introduced into the pH adjusting tank 19. Further, the wash water temporarily stored in the feed tank 18 is also introduced into the pH adjusting tank 19 and added to the fine-grained soil-containing water. In the pH adjusting tank 19, the pH of the fine-grained soil-containing water (including the added washing water) is adjusted to a pH adjusting agent such as an acidic liquid (for example, sulfuric acid or hydrochloric acid) and an alkaline liquid (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 19, the pH of the fine soil-containing water is automatically adjusted by a pH automatic control device equipped with a pH meter or the like.

  The fine-soil-containing water whose pH has been adjusted in the pH adjusting tank 19 is temporarily stored in the raw water tank 20. In the raw water tank 20, a polyaluminum chloride liquid (PAC), a polymer flocculant, and a pH adjuster (an acidic liquid or an alkaline liquid) are added to fine-grained soil-containing water. Thereby, many flocs in which water-insoluble metal hydroxide and fine-grained soil are mixed are generated in the raw water tank 20. At that time, water-polluting substances in the washing water are adsorbed on or attached to the floc. Note that the polyaluminum chloride liquid and the polymer flocculant may be added to the fine-grained soil-containing water in the pH adjusting tank 19 instead of the raw water tank 20. Moreover, you may provide between the pH adjustment tank 19 and the raw | natural water tank 20, the aggregation reaction tank which adds a polyaluminum chloride liquid, a polymer flocculant, and a pH adjuster to fine-grain soil containing water.

  The fine soil-containing water in the raw water tank 20 is introduced into the thickener 22 after the suspended matter is removed by the suspended matter collection device 21. Although the thickener 22 is not shown in detail, the water-insoluble flock or fine-grained soil is settled by gravity in a state where the fine-grained soil-containing water is almost stationary, and a sludge layer (for example, solid The proportion of the minute is 5 to 10%) and the supernatant water (wash water) which is located in the upper part and hardly contains flock or fine-grained soil is formed. The floating oil floating on the surface of the supernatant water is removed by overflowing a small amount of the supernatant water from the upper part of the thickener 22.

  Sludge staying or accumulating in the lower portion of the thickener 22 is extracted by a sludge pump or the like, transferred to the intermediate tank 23, and temporarily stored in the intermediate tank 23. Then, the sludge in the intermediate tank 23 is transferred to the filter press 24 as appropriate or continuously. Although not shown in detail, the filter press 24 is a batch-type or semi-continuous type pressure filter, and pressurizes and filters sludge received from the intermediate tank 23 to generate a filter cake and a filtrate. The filtration pressure of the filter press 24 is set so that the water content of the filter cake is 30 to 40%, for example. Here, the filtrate of the filter press 24 is returned to the thickener 22. A filter other than the filter press, for example, a vacuum filter (Oliver type filter) or the like may be used. Since the filter cake discharged from the filter press 24 contains almost no harmful metals or other contaminants, it can be used or sold as improved soil after being dried as necessary.

  On the other hand, the supernatant water in the thickener 22 is introduced into the treated water tank 25 and stored. When the treatment water tank 25 becomes full, the spare water tank 26 is used. The treated water stored in the treated water layer 25 or the reserve water tank 26 is introduced into the chelating agent regeneration unit 5 whose configuration and function will be described in detail later. In addition, when the treated water (circulated water) stored in the treated water tank 25 decreases due to evaporation or the like, the treated water tank 25 is appropriately replenished with tap water.

  In this contaminated soil purification apparatus S, soil contaminated with harmful metals or the like adheres to the soil when it is sequentially processed by the mixing device 12, the mill breaker 13, the trommel 14, the cyclone 15 and the sand screen 17. Hazardous metals and other pollutants or other pollutants are released into the wash water containing the chelating agent, but these contaminants released into the wash water are concentrated on the surface of fine soil with a relatively small particle size (environment). Ministry of Water, Atmospheric Environment Bureau, Soil Environment Division, “Technical considerations regarding permission review of contaminated soil treatment industry”, page 21, published in August 2013). Therefore, the coarse aggregate recovered by the trommel 14 or the sand (washed sand) recovered by the sand screen 17 contains almost no harmful metals and can be reused as a material for civil engineering and construction.

  As described above, toxic metals and other pollutants separated into the washing water during the flow from the mixing device 12 to the sand screen 17 are collected on the surface of the fine soil having a relatively small particle size. The soil is in contact with the cleaning water containing the chelating agent for a sufficiently long time (for example, 1 to 4 hours) in the course of distribution from the seal tank 16 or the feed tank 18 to the thickener 22. For this reason, most of the harmful metals and other contaminants adhering to the fine-grained soil are released into the washing water. Then, harmful metals and the like or other contaminants or these ions released in the washing water are captured by the chelating agent. Accordingly, the filter cake (improved soil) produced by the filter press 24 contains almost no harmful metals or other pollutants, and is dried using, for example, a continuous aeration band dryer or a ventilation rotary dryer. Can be reused.

  Hereinafter, the specific configuration and function of the chelating agent regeneration unit 5 of the contaminated soil purification apparatus S will be described with reference to FIG. As shown in FIG. 3, the chelating agent regeneration unit 5 is provided with a washing water regeneration device 30. The washing water reclaiming device 30 is attached to an elongated substantially cylindrical main body 31 that is long in the vertical direction, an agitator 32 that is disposed in the main body 31 and is driven to rotate by a motor, and an inner peripheral surface of the main body 31. And a plurality of annular baffle plates 33 (baffles). The stirrer 32 has a plurality of stirring blades or blades attached to a rotating shaft extending in the vertical direction.

  Here, the stirring blades and the baffle plates 33 are arranged so as to be alternately arranged in the vertical direction. The dimensions (for example, diameter, length, etc.) of the main body 31 are set so that the washing water and solid-phase adsorbent particles flowing in the main body 31 are set for a predetermined residence time (for example, 0.1 to 0.5 hours). ) Is preferably set. Further, the number, shape, rotation speed, and the like of the stirring blades of the stirrer 32 achieve a degree of turbulence (Reynolds number) such that the solid-phase adsorbent particles are dispersed almost uniformly in the washing water in the main body 31. It is preferably set so that.

  Then, after the supernatant water or the washing water discharged from the thickener 22 (sediment separation part 3) is temporarily stored in the treated water tank 25 or the reserve water tank 26 in the upper end opening of the main body 31, the pump 35 is used. It is supplied via a pipe 36. Further, the solid-phase adsorbent particles stored in the solid-phase adsorbent particle storage tank 37 are supplied to the upper end opening of the main body 31 by the particle feeder 38. The washing water and the solid-phase adsorbent particles supplied to the upper end opening of the main body 31 are stirred and mixed by the stirrer 32, and the solid-phase adsorbent particles are dispersed almost uniformly in the washing water (hereinafter referred to as “washing”). The washing water / particle mixture is generally stirred downward by the plurality of stirring blades of the stirrer 32 and flows downward in the main body 31.

  Thus, in the cleaning water regenerator 30 (main body portion 31), the cleaning water containing a chelating agent capturing toxic metals and the like or these ions has a higher solid-phase adsorbent (solid phase) than the chelating agent. Adsorbent particles). As a result, harmful metals or the like captured by the chelating agent or these ions are released from the chelating agent and are adsorbed or extracted by the solid phase adsorbent. As a result, harmful metals and the like are removed and collected from the cleaning water, while the chelating agent is again in a state where it can capture the harmful metals and the cleaning water is regenerated. Here, the plurality of baffle plates 33 increase the degree of turbulence (Reynolds number) of the cleaning water / particle mixture in the main body 31, thereby promoting the removal of harmful metals and the like from the chelating agent by the solid phase adsorbent. The

  After the chelating agent is thus regenerated, the washing water / particle mixture is washed from the lower end opening in the main body 31 to wash the washing water / particle mixture into washing water and solid-phase adsorbent particles. Introduced into the separation screen 40. As the cleaning water separation screen 40, for example, a preset mesh mesh (diameter) or a tilted / horizontal vibratory screen or a circular vibratory screen in which a mesh is inclined can be used. Here, the opening of the wire mesh or mesh of the washing water separation screen 40 is preferably set so that the solid adsorbent particles do not pass and the washing water can pass smoothly.

  Thus, the wash water that has passed through the wire mesh of the wash water separation screen 40 is introduced into the wash water storage tank 41 and stored. The cleaning water stored in the cleaning water storage tank 41 is supplied (refluxed) to the mixing device 12, the trommel 14, and the sand screen 17 through the pipe line 43 by the pump 42. The pump 42 and the pipe line 43 constitute a washing water reflux mechanism. On the other hand, the solid-phase adsorbent particles that do not pass through the wire mesh of the washing water separation screen 40 are discharged from the washing water separation screen 40, and then are solid-phase adsorbent particle storage tank 37 by the first bucket conveyor 45 and the first belt conveyor 46. Will be returned.

  Hereinafter, the specific configuration and function of the solid-phase adsorbent regeneration mechanism will be described. When the amount of adsorption of toxic metal or the like of the solid-phase adsorbent in the solid-phase adsorbent particles discharged from the washing water separation screen 40 reaches a saturated state or the vicinity thereof, the solid-phase adsorbent particles are separated from the second bucket conveyor 47 and It is transferred to the acid solution cleaning device 50 by the second belt conveyor 48. Then, the acid solution cleaning apparatus 50 is supplied with the acid solution stored in the acid solution storage tank 51 via the pipe line 53 by the pump 52.

  The acid cleaning apparatus 50 is attached to an elongated substantially cylindrical main body 54 that is elongated in the vertical direction, an agitator 55 that is disposed in the main body 54 and is driven to rotate by a motor, and an inner peripheral surface of the main body 54. And a plurality of baffles 56 having an annular shape. The stirrer 55 has a plurality of stirring blades or blades attached to a rotating shaft extending in the vertical direction. Here, the stirring blades and the baffle plates 56 are arranged so as to be alternately arranged in the vertical direction. The dimensions (for example, diameter, length, etc.) of the main body 54 are set so that the acid solution and the solid-phase adsorbent particles flowing in the main body 54 have a preset residence time (for example, 0.1 to 0.3 hours). ) Is preferably set. Further, the number, shape, rotation speed, and the like of the stirring blades of the stirrer 55 achieve a degree of turbulence (Reynolds number) such that the solid-phase adsorbent particles are dispersed almost uniformly in the acid solution in the main body 54. Is preferably set.

  The acid solution and the solid phase adsorbent particles to be regenerated are supplied to the upper end opening of the main body 54 of the acid solution cleaning apparatus 50, and the acid solution and the solid phase adsorbent particles are stirred and mixed by the stirrer 55. Thus, a mixture (hereinafter referred to as “acid solution / particle mixture”) in which the solid-phase adsorbent particles are substantially uniformly dispersed in the acid solution is generated, and the acid solution / particle mixture is a plurality of stirring blades of the stirrer 55. Flows downward in the main body 54 while being stirred.

  Thus, in the acid solution cleaning apparatus 50 (main body portion 54), the solid-phase adsorbent particles are brought into contact with the acid solution, and harmful metals or the like captured by the solid-phase adsorbent or these ions are released into the acid solution. Be made. Thereby, harmful metals and the like are removed from the solid-phase adsorbent, and the solid-phase adsorbent or solid-phase adsorbent particles are regenerated. Whether or not the amount of harmful metal adsorption of the solid-phase adsorbent reaches a saturated state or the vicinity thereof can be determined by detecting the content of harmful metals in the washing water discharged from the washing water separation screen 40. it can. The baffle plate 56 increases the degree of turbulence (Reynolds number) of the acid solution / particle mixture in the main body portion 54, thereby promoting the removal of harmful metals and the like from the solid-phase adsorbent.

  After the solid-phase adsorbent is regenerated in this way, the acid solution / particle mixture is separated from the lower end opening of the main body 54 by an acid for separating the acid solution / particle mixture into an acid solution and solid-phase adsorbent particles. It is introduced into the liquid separation screen 57. As the acid-liquid separation screen 57, for example, a preset mesh screen (caliber) wire mesh or a tilted / horizontal type vibration sieve in which a mesh is inclined, or a circular type vibration sieve can be used. Here, the opening of the mesh or mesh of the acid liquid separation screen 57 is the same as that of the washing water separation screen 40.

  Thus, the acid solution that has passed through the metal mesh of the acid solution separation screen 57 is returned to the acid solution storage tank 51 and stored. The acid solution stored in the acid solution storage tank 51 is again supplied to the acid solution cleaning device 50 via the pipe line 53 by the pump 52. On the other hand, the solid-phase adsorbent particles that do not pass through the metal screen of the acid liquid separation screen 57 are discharged from the acid liquid separation screen 57 and then transferred to the water washing device 60 by the third bucket conveyor 58 and the third belt conveyor 59. .

  The water washing apparatus 60 has a substantially cylindrical main body 61 and a stirrer 62 that is disposed in the main body 61 and is rotationally driven by a motor. The stirrer 62 has one or a plurality of stirring blades or blades attached to a rotary shaft extending in the vertical direction. Rinse water and solid-phase adsorbent particles to be washed are supplied to the upper end opening of the main body 61, and the rinse water and solid-phase adsorbent particles are agitated and mixed by a stirrer 62. A mixture (hereinafter referred to as “water / particle mixture”) that is almost uniformly dispersed in the rinse water is produced. Thus, in the water washing apparatus 60 (main body 61), the solid-phase adsorbent particles are brought into contact with the rinse water, and the acid solution adhering to the solid-phase adsorbent is removed. This completes the regeneration of the solid-phase adsorbent or solid-phase adsorbent particles.

  Thereafter, the water / particle mixture is introduced into the water separation screen 63 for separating the water / particle mixture into rinse water and solid-phase adsorbent particles from the lower end opening of the main body 61 of the water washing device 60. As the water separation screen 63, for example, a preset mesh screen (diameter) or a tilted / horizontal vibratory screen or a circular vibratory screen in which a mesh is inclined can be used. Note that the mesh of the metal screen or mesh of the water separation screen 63 is the same as that of the washing water separation screen 40.

  Thus, the rinse water that has passed through the wire mesh of the water separation screen 63 is introduced into the water storage tank 64 and stored. The rinse water stored in the water storage tank 64 is again supplied to the water washing apparatus 60 via the pipe line 66 by the pump 65. On the other hand, the solid-phase adsorbent particles that do not pass through the wire separation screen 63 are discharged from the water separation screen 63 and then returned to the solid-phase adsorbent particle storage tank 37 by the fourth bucket conveyor 67 and the fourth belt conveyor 68. Is done.

  In the chelating agent regeneration unit 5 according to the present invention, the means for transferring or returning the solid-phase adsorbent particles is not limited to a combination of a bucket conveyor and a belt conveyor, but a conveying device that can convey granular materials. Anything is acceptable. The first to fourth bucket conveyors 45, 47, 58, and 67 and the first to fourth belt conveyors 46, 48, 59, and 68 constitute a solid-phase adsorbent particle returning mechanism. Further, the acid solution cleaning device 50, the acid solution separation screen 57, the acid solution storage tank 51, the water washing device 60, the water separation clean 63, the water storage tank 64, the pumps 52 and 65, and the pipe lines 53 and 66 are a solid-phase adsorbent regeneration mechanism. Configure.

  According to the contaminated soil purification device S or the chelating agent regeneration unit 5 according to the present invention, the soil discharged from the crushing unit 1 (mixing device 2, mill breaker 3) is classified into the classification unit 2 (trommel 14, cyclone 15, sand screen). In 17), since it is washed with washing water containing a chelating agent, harmful metals and the like adhering to coarse aggregate (stone and / or gravel), sand, fine-grained soil, etc. contained in the soil are removed. For this reason, the coarse aggregate or sand separated and collected by the classifying unit 2 or the fine-grained soil contained in the filter cake discharged from the filter unit 4 (filter press 24) contains almost no harmful metals. Therefore, coarse aggregate or sand can be used as a civil engineering / building material, and a filter cake can be used as, for example, improved soil. Therefore, it is possible to generate coarse aggregate, sand (washed sand) and / or fine-grained soil (improved soil) that can be reused with almost no harmful metals, etc., from soil contaminated with harmful metals. . Further, by using a specific chelating agent, it is possible to remove specific contaminants other than harmful metals, such as boron and fluorine.

  In addition, washing water containing a chelating agent is circulated and used, and harmful metals captured by the chelating agent in the middle of the circulation are removed by the solid-phase adsorbent, and are appropriately adsorbed by the solid-phase adsorbent. Harmful metals and the like are removed by the acid solution. For this reason, it is necessary to continuously purify a large amount of soil contaminated with harmful metals, etc. with almost no replenishment of chelating agents or solid-phase adsorbents, and clean aggregates or coarse aggregates, washing sand, improved soils, etc. Can be generated.

  Therefore, according to the contaminated soil purification apparatus S or the chelating agent regeneration unit 5 according to the present invention, using the method for purifying hazardous metal contaminants according to the invention described in Patent Document 4, Furthermore, it becomes possible to actually purify toxic metal-contaminated soil containing predetermined contaminants other than toxic metals as a business.

  As described above, the contaminated soil purification apparatus S according to the present invention is useful for purification of a large amount of soil contaminated with harmful metals and the like, and particularly the site of a production facility that uses harmful metals and the like as raw materials or materials or the like. It is suitable for eliminating soil contamination in nearby areas or disposal of industrial waste containing hazardous metals.

  S Contaminated soil purification device, 1 crushing section, 2 classification section, 3 sedimentation separation section, 4 filtration section, 5 chelating agent regeneration section, 11 charging hopper, 12 mixing device, 13 mill breaker, 14 trommel, 15 cyclone, 16 seal tank , 17 Sand screen, 18 Feed tank, 19 pH adjustment tank, 20 Raw water tank, 21 Floating substance recovery device, 22 Thickener, 23 Intermediate tank, 24 Filter press, 25 Treated water tank, 26 Spare water tank, 30 Washing water regeneration device, 31 Main body part, 32 stirrer, 33 baffle plate, 35 pump, 36 conduit, 37 solid phase adsorbent particle storage tank, 38 particle feeder, 40 cleaning water separation screen, 41 cleaning water storage tank, 42 pump, 43 conduit, 45 1st Bucket conveyor, 46 1st belt conveyor, 47 2nd bucket conveyor, 48 2nd belt conveyor, 50 acid solution cleaning device, 51 acid solution storage tank, 52 pump, 53 conduit, 54 body, 55 stirrer, 56 baffle plate, 57 acid solution separation screen, 58 3rd bucket conveyor, 59 3rd belt Conveyor, 60 water washing device, 61 main body, 62 agitator, 63 water separation screen, 64 water storage tank, 65 pump, 66 pipe, 67 fourth bucket conveyor, 68 fourth belt conveyor.

Claims (4)

Accepting soil contaminated with stones or gravel and contaminated with a toxic metal or a compound thereof, and wash water containing a chelating agent having a chelating agent concentration in the range of 0.01 to 0.05 mol / liter; By applying impact force, shearing force and frictional force to the stones or gravel mixed in the soil, the stones or gravel is crushed and a part of the harmful metal or its compound adhering to the stones or gravel is removed from the soil. A wet rod mill that is detached from the washing water and captured by the chelating agent ,
A mixture of soil and washing water discharged from the rod mill is received in a drum screen, and a chelating agent concentration is in the range of 0.01 to 0.05 mol / liter in the mixture flowing in the drum screen. By spraying the wash water containing the agent, harmful metals remaining or adhering to the soil or their compounds are separated from the soil and captured by the chelating agent, and the coarse aggregate is separated and removed from the soil. Trommel to do,
A cyclone that receives the mixture of soil and wash water discharged from the trommel and separates it into sand and a mixture of fine-grained soil and wash water;
A sedimentation separation unit that separates the mixture of fine-grained soil and washing water discharged from the cyclone into supernatant water and sludge containing fine-grained soil by sedimentation separation;
A chelating agent regeneration unit that receives the supernatant water discharged from the sedimentation separation unit, removes the harmful metal or the compound from the chelating agent capturing the harmful metal or the compound in the supernatant water, and regenerates the chelating agent. A contaminated soil purification device comprising:
The chelating agent regeneration unit is
Solid-phase adsorbent particles comprising a solid-phase adsorbent that adsorbs a harmful metal or a compound thereof in the supernatant water when it comes into contact with the supernatant water discharged from the sedimentation separation unit with a higher complexing power than the chelating agent; A washing water regeneration device that mixes and stirs the supernatant water discharged from the sedimentation separation unit, removes harmful metals or compounds thereof from the chelating agent in the supernatant water, and regenerates the supernatant water as washing water;
A washing water separation screen for separating the washing water from the mixture of the solid-phase adsorbent particles and the washing water discharged from the washing water regenerator;
A washing water reflux mechanism for refluxing the washing water discharged from the washing water separation screen to the rod mill and the trommel ;
The solid-phase adsorbent particles discharged from the washing water separation screen are mixed with an acid solution, and the harmful metal adsorbed on the solid-phase adsorbent particles or a compound thereof is washed and removed with the acid solution , and the solid-phase adsorbent particles An acid cleaning device for regenerating
An acid liquid separation screen for separating the acid liquid from the mixture of the solid phase adsorbent particles discharged from the acid liquid cleaning apparatus and the acid liquid;
A water washing device for mixing the solid phase adsorbent particles discharged from the acid liquid separation screen with rinsing water, and washing the solid phase adsorbent particles with water,
A water separation screen for separating rinse water from a mixture of solid phase adsorbent particles and rinse water discharged from the water washing device;
A solid-phase adsorbent particle returning mechanism for returning the solid-phase adsorbent particles discharged from the washing water separation screen or the solid-phase adsorbent particles discharged from the water separation screen to the washing water regeneration device,
The solid-phase adsorbent has a multipoint interaction by coordination bonds and hydrogen bonds in which a cyclic molecule is supported on a carrier and a chelate ligand is modified on the cyclic molecule, and ions of harmful metals or their compounds are selectively used. A contaminated soil purification apparatus characterized by being incorporated.   The washing water regenerator causes an inlet part into which solid-phase adsorbent particles and washing water flow, and a mixture of the solid-phase adsorbent particles and washing water flowing in from the inlet part to flow in the longitudinal direction thereof. The flow reactor according to claim 1, comprising a cylindrical main body, a stirrer for stirring the mixture in the main body, and an outlet for discharging the mixture from the main body. The contaminated soil purification device described. A mixing device for supplying to the rod mill was mixed with wash water supplied hazardous metal or with contaminated soil in the compound from the wash water recirculation mechanism,
The cleaning process is performed with rinsing discharged sand from said cyclone, and having a sand SCREEN is removed by collecting the suspended matter or foreign remaining, according to claim 1 or 2 Contaminated soil purification equipment. The contaminated soil purification apparatus according to any one of claims 1 to 3 , further comprising a filtering unit that filters sludge discharged from the sedimentation separation unit to generate a filter cake.

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