JP6544609B1 - Soil purification system - Google Patents

Abstract

Provided is a simple and low-cost soil purification system capable of wet classification of soil into gravel, sand, and fine particles while removing harmful metals and the like adsorbed on the fine particles. A soil purification system (S) is classified into gravel, sand and fine particles while washing soil with washing water by a mill breaker (3), a trommel (4), a hydrocyclone (5) and a thickener (8). The iron content removing device 12 magnetically adsorbs and removes iron-based fine particles from the sludge discharged from the thickener 8 to reduce the content rate of harmful metals and the like in the sludge. The fine particle content cleaning device 13 cleans the sludge discharged from the iron content removing device 12 with a chelate cleaning solution to remove harmful metals and the like from the fine particles. The filtering device 14 filters the sludge discharged from the iron content removing device 12. The reverse osmosis membrane separation device 16 separates the filtrate of the filtration device 14 into permeate and retentate. The chelating agent regenerating apparatus 17 removes harmful metals and the like from the concentrated water and supplies it to the fine particle size washing apparatus 13 as a chelate washing solution. [Selected figure] Figure 1

Description

  TECHNICAL FIELD The present invention relates to a soil remediation system that purifies soil that contains straw, sand, and fine particles and that is contaminated with harmful metals and / or compounds thereof.

  In recent years, for example, harmful metals such as chromium, lead, cadmium, selenium, mercury and / or compounds thereof (hereinafter, these are collectively referred to as "harmful metals etc.") In the country, soil pollution occurs frequently due to soil pollution or illegal dumping of industrial waste containing harmful metals. Then, soil contaminated with harmful metals (hereinafter referred to as “toxic metal-contaminated soil”) is present at a position (hereinafter referred to as “in-situ position”), for example, insolubilization of harmful metals or the like, containment or electrical repair It is rather difficult to clean up more effectively. For this reason, harmful metal-contaminated soil is generally removed from the in-situ site by drilling and purified at an external soil purification facility.

  As a method of purifying harmful metal-contaminated soil at such a soil purification facility outside the in-situ site, conventionally, a washing method of washing harmful metal-contaminated soil with washing water etc. to remove harmful metals etc. is widely used . Then, when the harmful metal-contaminated soil is washed with washing water, most of the harmful metals and the like that have been temporarily removed from the soil are adsorbed or adhered to the surface of the relatively small particle size fine particles, and the fine particles It is known to be concentrated on the surface of (see, for example, Non-Patent Document 1).

  Therefore, by classifying the harmful metal contaminated soil with washing water while classifying it into sand, sand and fine particles, the fine particles are subjected to a chemical treatment to remove harmful metals and the like. It is possible to obtain straw, sand and fine particles containing almost no harmful metals. Thus, the applicant has already classified the harmful metal-contaminated soil with washing water, and classified it into gravel, sand and fine particles, and then a chelating cleaning solution containing a chelating agent and water for the fine particles. Various soil purification facilities (contaminated soil purification devices) have been proposed in which harmful metals and the like are removed from fine particles by performing washing treatment (see, for example, Patent Documents 1 and 2).

Patent No. 5723054 gazette Patent No. 5723055 gazette Patent No. 4755159 gazette Patent No. 60071144 gazette

Ministry of the Environment Water and Atmosphere Environment Bureau Soil Environment Division "Technical notes on permission assessment etc. of contaminated soil treatment industry" page 21, published in August 2013 Tetsuo Katsura "Drainage treatment by iron powder method" flotation, vol. 23 (1976), no. 3, P190-198 (https://www.jstage.jst.go.jp/article/rpsj1954/23/3/23_3_190/_pdf)

  By the way, in this kind of soil remediation facility by a contaminated soil treatment company, a large amount of contaminated soil is usually cleaned (for example, 2000 tons per day), so a large amount of fine particles is generated (for example, on a dry basis) 500 to 600 tons per day). Therefore, when such a large amount of fine particles is washed with, for example, a chelate washing solution, a large amount of a relatively expensive chelating agent is required, resulting in a problem that the cost of treating contaminated soil increases. The necessary amount or use amount of the chelating agent in such a soil remediation facility increases as the content of the fine particles of harmful metals and the like increases. The same problem occurs when the fine particles are washed with chemicals other than chelating agents to remove harmful metals and the like. In addition, the same problem arises when removing harmful metals and the like more physicochemically using activated carbon and the like.

  The present invention has been made to solve the above-mentioned conventional problems, and comprises washing with soil and containing soil, sand and fine particles and contaminated with harmful metals and the like while washing the soil with washing water. It is an object of the present invention to provide a simple and low-cost soil remediation system which can be classified into fine particles and capable of removing harmful metals and the like adsorbed or attached to separated fine particles. It is an issue to be solved.

  The soil remediation according to the present invention made to solve the above-mentioned problems according to the present invention, which comprises soot, sand and fine particles and purifies soil contaminated with harmful metals etc (hazardous metals and / or compounds thereof) or these ions The system includes a mixer, a wet crusher, a trommel, a hydrocyclone, a thickener, an iron removing device, a fine particle washing device, a filtration device, a reverse osmosis membrane separation device, and a chelating agent regenerating device , And a permeated water transfer means.

  Here, the mixer mixes the soil introduced into the soil purification system with the washing water. The wet crusher is iron and / or unevenly distributed or scattered within the gravel and / or sand by crushing the gravel and / or sand in the mixture containing the soil and the washing water discharged from the mixer. Or iron oxide (hereinafter collectively referred to as "iron etc.") forms iron-based fine particles exposed on the surface, and iron etc. exposed to the surface of iron-based fine particles Harmful metals in cleaning water etc. Adsorb (adhere). The trommel separates the straw from the mixture discharged from the wet crusher, which contains straw, sand, fines and wash water. A hydrocyclone separates sand from a mixture comprising sand, fines and wash water discharged from the trommel. The thickener separates the mixture containing the fines and the wash water discharged from the hydrocyclone into the supernatant water and the sludge containing the fines and the wash water by sedimentation.

  The iron content removing device reduces the content of harmful metals and the like of the sludge by magnetically removing the iron-based fine particles from the sludge discharged from the thickener by magnetic adsorption. The iron-based fine particles contain iron and the like to such an extent that they can be adsorbed by magnetic force. The fine particle washing apparatus mixes the sludge discharged from the iron removing apparatus with a chelating washing solution containing a chelating agent and water to form a fine particle slurry, and the fine particle slurry has a preset residence time. The chelating agent is allowed to trap harmful metals or the like or these ions attached (adsorbed) to the fine particle content by flowing so as to ensure. The filtration device filters the fine particle slurry discharged from the fine particle washing device to produce a filtrate and a filter cake.

  The reverse osmosis membrane separation device separates the filtrate discharged from the filtration device into the concentrated water in which the chelating agent is concentrated and the permeated water which does not contain the chelating agent by the reverse osmosis membrane. The chelating agent regenerator receives concentrated water discharged from the reverse osmosis membrane separation device, and has a higher complexing power than the chelating agent, and adsorbs harmful metals and the like in the concentrated water when contacted with the concentrated water. The solid phase adsorbent removes harmful metals and the like from the chelating agent in the concentrated water, and the concentrate is supplied to the fine particle size washing apparatus as a chelating washing solution. The permeated water transfer means transfers (returns) the permeated water discharged from the reverse osmosis membrane separation device to the thickener.

  The iron removal device has an iron-based fine particle adsorption device, a screen device, a centrifugal separator, and a magnetic ball return device. The iron-based fine particle adsorption device comprises a plurality of (a plurality of permanent magnets are attached to the hollow portion of a hollow spherical body so that the same magnetic poles (N pole or S pole) are directed outward in the radial direction of the spherical body ) And the sludge discharged from the thickener in the upper part of a zigzag or groove-like air passage, and the mixture of the magnetic ball and the sludge is moved downward by gravity in the air passage. At the time of movement, the iron-based fine particles in the sludge are adsorbed onto the magnetic spheres by magnetic force. The screen device receives the mixture of magnetic spheres and sludge discharged from the lower or lower end of the iron-based fine particle adsorption device, and separates (screens) it into magnetic spheres and sludge. The centrifuge intermittently receives the magnetic spheres, which adsorbs the iron-based fine particles, discharged from the screen device in a batch system (batch system), and the iron-based particles from the magnetic spheres by centrifugal force. Let go. The magnetic sphere return device returns the magnetic spheres discharged from the centrifuge and hardly adsorbing the iron-based fine particles to the iron-based fine particle adsorption device.

  In the soil purification system according to the present invention, the air passage of the iron-based fine particle adsorption device is constituted of a plurality of linear channel members disposed in an inclined manner so as to lead downward in a zigzag manner. preferable.

  In the soil purification system according to the present invention, it is preferable that the magnetic sphere return device comprises an upright belt conveyor, magnetic sphere conveyance means, and magnetic sphere supply means. Here, the upright belt conveyor includes a driving roller disposed at a position lower than the lower end of the centrifuge and a driven roller disposed at a position higher than the upper end of the iron-based fine particle adsorption device above the driving roller. And an endless metal belt made of ferromagnetic metal wrapped around a driving roller and a driven roller, and attached to the outer surface of the endless metal belt and attracted to the endless metal belt when traveling over the endless metal belt It is preferable to have a magnetic ball locking member for locking the lowering of the magnetic ball. In this case, the magnetic ball transport means transports the magnetic spheres discharged from the centrifuge to the lower end portion of the upright belt conveyor or in the vicinity thereof and causes the endless metal belt to attract the magnetic spheres by magnetic force. Also, the magnetic sphere supply means separates the magnetic spheres from the endless metal belt at or near the upper end of the upright belt conveyor and supplies (moves) the iron-based fine particle adsorption device.

  Generally, in the process of washing and classification of contaminated soil using washing water, harmful metals and the like are hardly adsorbed (adhered) on the gravel and sand, but collected in fine particles and adsorbed (adhered) (for example, non-adhesion) Patent Document 1). The fine particle content is a relatively small amount of iron-based fine particle content containing iron etc. to an extent that can be adsorbed by magnetic force, and a relatively large amount of fine particle content that can not be adsorbed by magnetic force other than iron-based fine particle content (hereinafter Non-ferrous fine particles). On the other hand, since iron and the like have the property of adsorbing harmful metals and the like (see, for example, Non-patent Document 2), the amount of adsorbed harmful metals and the like of iron-based fine particles including iron etc. exposed on the surface (adhesion amount ) Is considerably larger than the adsorption amount (adhesion amount) of harmful metals and the like of non-ferrous fine particles.

  And, according to the soil remediation system according to the present invention, the gravel and / or sand are crushed by the wet crusher to generate fine particles, and among these fine particles, uneven distribution or in sand or sand Fine particles containing a large amount of small agglomerates such as iron scattered are iron-based fine particles, and iron etc. exposed on the surface of these iron-based fine particles are transferred from a wet crusher to an iron removal device Adsorbs relatively large amounts of harmful metals etc. in a series of distribution processes. Therefore, iron-based fine particles existing before crushing and iron-based fine particles generated by crushing are introduced into the iron-removing apparatus, and all of these iron-based fine particles are considerably large (non-ferrous It adsorbs harmful metals, etc.) compared to the system fines.

  Thus, in the iron-based fine particle content adsorption device of the iron content removal device, the mixture in which the magnetic spheres and the sludge are mixed travels downward by gravity in the trough-like or groove-like air passage which descends in a zigzag manner. The iron-based fine particles in it are attracted to the magnetic spheres by magnetic force. Thus, since the iron-based fine particles in the sludge having a large amount of adsorption of harmful metals and the like are adsorbed by the magnetic spheres and removed from the sludge, the content or retention of harmful metals and the like in the sludge can be reduced. it can. Therefore, the load of harmful metals and the like on the fine particle washing apparatus for purifying the sludge discharged from the iron content removing apparatus (iron-based fine particle adsorption apparatus) with the chelate washing solution, and the chelating agent regeneration for removing harmful metals and the like from the chelating agent The load of harmful metals and the like on the apparatus can be reduced, the necessary amount or use amount of the chelating agent and the solid phase adsorbent can be reduced, and the processing cost of the soil can be reduced. The wet crusher and the iron removal device are of mechanical construction to apply physical treatment and do not use special chemicals, so their operating cost is very low.

  In each of the magnetic spheres, a plurality of permanent magnets are mounted in the hollow portion of the hollow sphere so that the same magnetic poles (for example, the N pole) are directed outward in the radial direction of the sphere. Repel each other. For this reason, in the iron-based fine particle adsorption device, on the screen device, or in other magnetic ball moving paths, the magnetic spheres do not adsorb to each other to form a lump (a bunch of grapes), and each magnetic sphere Can repel each other, move appropriately, and move smoothly.

It is a block diagram showing a schematic structure of a soil purification system concerning the present invention. It is a typical elevation view of the iron content removal apparatus which comprises a soil purification system. It is a typical elevational cross-sectional view of the iron-type fine particle content adsorption device which constitutes an iron content removal device. It is a typical sectional view of a magnetic sphere. It is a typical partial cross section elevation view of a centrifuge. (A) is a schematic side view of a part of the magnetic ball transfer conveyor and the upright belt conveyor, (b) is a schematic side view of a part of the upright belt conveyor, (c) is an upright It is a typical front view of a part of model belt conveyor. (A) is a schematic plan view of the fine particle washing apparatus, (b) is a sectional view taken along line A-A of the fine particle washing apparatus shown in (a), (c) is the fine particle washing FIG. 5 is an elevational cross-sectional view of one slurry passage of the device. It is a typical elevation view of a chelating agent regeneration device.

  As shown in FIG. 1, in the soil purification system S according to the embodiment of the present invention, soil collected by excavating ground contaminated with harmful metals etc. (hazardous metals and / or compounds thereof) or these ions The (contaminated soil) is received in the input hopper 1. Examples of the harmful metals include chromium, lead, cadmium, selenium, mercury, metal arsenic and the like. Then, the soil in the charging hopper 1 is continuously or intermittently charged into the mixer 2 and mixed with the washing water continuously supplied to the mixer 2. Here, the soil includes a weir (for example, a particle size of 2 to 75 mm), sand (for example, a particle size of 0.075 to 2 mm), and a fine particle fraction (for example, a particle size of 0.075 mm or less) In some cases, it also contains stones (eg, a particle size of 75 mm or more).

  A mixture containing soil and wash water generated by the mixer 2 (hereinafter referred to as "soil / water mixture") is transferred to a mill breaker 3 which is a wet crusher. For example, a rod mill can be used as the mill breaker 3. Although not shown in detail, the rod mill is a crushing apparatus in which a plurality of rods (for example, 10 75 mmφ × 2 m steel rods) are disposed in a drum, and the rods rotate parallel to one another by rotation of the drum. Can move into line contact and break up gravel and sand (in some cases even stones) by their impact force, shear force, frictional force etc. to produce small diameter soil particles such as fines . A ball mill or the like can be used as the mill breaker 3 in addition to the rod mill. In addition, a part of the gravel and the sand become fine particles, and not all the fine particles.

  Thus, the mill breaker 3 crushes sand and sand (in some cases, stones) in the soil-water mixture discharged from the mixer 2 to generate small-diameter soil particles such as fine particles. As a result, harmful metals and the like adsorbed (adhered) or contained in the straw and sand are released into the water. At this time, basically (except for adsorption by iron and the like described later), harmful metals and the like released in water are hardly adsorbed or not attached to straw and sand, and collected into fine particles and adsorbed. Or attach (see, for example, Non-Patent Document 1).

  In addition, a large number of iron-based fine particles are generated in which micro-mass of iron or the like (iron and / or iron oxide) unevenly distributed or scattered in the straw and sand is exposed to the surface. On the other hand, iron and the like generally have the property of adsorbing harmful metals and the like. For this reason, some of the harmful metals and the like or these ions present in the wash water are adsorbed or attached to the exposed surface of the iron-based fine particles such as iron. As a result, the adsorption amount (adhesion amount) of harmful metals and the like of iron-based fine particles is considerably larger than the adsorption amount (adhesion amount) of harmful metals and the like of non-ferrous fine particles. That is, the fine particles discharged from the mill breaker 3 are iron-based fine particles having a large amount of adsorption (adhesion) of harmful metals etc. and non-ferrous fine particles having a small amount of adsorption (adhesion) of harmful metals etc. And consists of In addition, it is needless to say that iron-based fine particles existing before crushing also adsorb considerably more harmful metals and the like than non-ferrous-based fine particles.

  The iron-based fine particles that adsorb the harmful metals and the like in this manner are removed by the iron removing device 12 as described later. On the other hand, it is generally known that iron and the like (iron and / or iron oxide) have the property of adsorbing harmful metals and the like, and utilizing this property, iron powder or iron oxide is contained in sludge containing harmful metals and the like. Various "iron powder methods" have been proposed in which harmful metals and the like are removed from sludge by adding powder (see, for example, Patent Documents 3 to 4 and Non-Patent Document 2). However, as in the present invention, crushing iron and sand forms iron-based fine particles in which fine lumps such as fresh iron (which has not adsorbed harmful metals and the like yet) are exposed on the surface. Processing methods for harmful metals and the like in which harmful metals and the like are made to be adsorbed to the exposed micro-mass (iron-based fine particles) such as iron have not been proposed yet by persons other than the applicant or the inventor of the present application. .

  The soil / water mixture discharged from the mill breaker 3 is introduced into the trommel 4. Although not shown in detail, the trommel 4 is a sieving device having a receiving tank capable of storing water, and a substantially cylindrical drum screen disposed to be inclined with respect to a horizontal surface, and the drum screen Is rotatable about its central axis (the central axis of the cylinder) by a motor. In addition, the washing water can be sprayed in the form of a spray into the drum screen.

  As the soil-water mixture flows inside the rotating drum screen of Trommel 4, soil particles finer than the mesh of the drum screen pass through the mesh of the drum screen together with the washing water and go out of the drum screen to the inside of the receiving tank to go into. On the other hand, since soil particles coarser than the mesh of the drum screen can not pass through the mesh of the drum screen, they are discharged out of the drum screen via the lower open end of the drum screen.

  In the trommel 4, the classification diameter (opening) of the mesh of the drum screen is set such that soil particles having a particle size of less than 2 mm, that is, sand and fine particles pass through the mesh of the drum screen. Therefore, in this trommel 4, a weir, which is a soil particle having a particle size of 2 mm or more (sometimes also a stone) is separated from the soil-water mixture. As mentioned above, since harmful metals and the like released in water are hardly adsorbed or attached to the sand and sand, the sand separated by the trommel 4 is substantially clean, for example, as an aggregate for concrete, etc. It can be used. The mesh size (opening) of the drum screen of the trommel 4 is not limited to the above, and of course it can be set arbitrarily according to the particle size of the soil particles to be obtained. It is.

  A soil-water mixture containing soil particles having a particle diameter of less than 2 mm, ie, sand and fine particles, contained in the receiving tank of the trommel 4 and washing water is introduced into a cyclone 5 (hydrocyclone). Although not shown in detail, the cyclone 5 pumps the soil-water mixture into a generally conical cylinder that narrows downward to generate a swirling flow, and the centrifugal force generated thereby is used to A mixture of soil and water, a mixture of fine particles having a relatively small particle size (for example, particle size less than 0.075 mm) and water, sand having a relatively large particle size (for example, a particle size of 0.075 mm or more) and water Separated into a mixture of

  Then, a mixture of fine particles and water (hereinafter referred to as “fine-grain-containing water”) is discharged from the upper end of the cyclone 5, and a mixture of sand and water having a relatively large particle diameter is discharged from the lower end of the cyclone 5. Be done. Here, since the sand discharged from the lower end portion of the cyclone 5 hardly contains harmful metals and the like as described above, it is drained or dried and used as regenerated sand. On the other hand, the fine particle-containing water is transferred to the PH adjustment tank 6.

  In the PH adjustment tank 6, the pH (hydrogen index) of the fine particle-containing water is approximately neutral using an acid solution (eg, sulfuric acid, hydrochloric acid) and an alkali solution (eg, sodium hydroxide aqueous solution) Adjusted. Although not shown, in the pH adjustment tank 6, the pH of the fine particle-containing water is automatically adjusted by a pH automatic control device equipped with a pH meter or the like.

  The fine particle-containing water whose pH has been adjusted in the PH adjustment tank 6 is introduced into the aggregation tank 7. In the coagulation tank 7, a polyaluminum chloride (PAC) aqueous solution, a polymer flocculant, and a pH adjuster (acidic solution or alkaline solution) are added to the fine particle-containing water. As a result, a large number of flocs in which the water-insoluble metal hydroxide and the fine particles are mixed are generated in the aggregation tank 7.

  Fine-grain-containing water (including floc) in the coagulation tank 7 is introduced into the thickener 8 (gravity settling tank). The chicna 8 is not shown in detail, but the non-water-soluble floc or fines are caused to settle by gravity while the fines-containing water is almost stationary, and the sludge layer located at the lower part (for example, solid) (5 to 10%) and a supernatant (wash water) which is located on the top and contains almost no floc or fines. When floated oil floats on the surface of the supernatant water, the floated oil is removed by overflowing a small amount of supernatant water from the top of the thickener 8.

  Supernatant water in the chicna 8 is introduced into the washing water tank 10 and temporarily stored. When the washing water tank 10 is full, the spare water tank 11 is used. The washing water stored in the washing water layer 10 or the reserve water tank 11 is supplied to the mixer 2 and the trommel 4 as circulating water. When the wash water stored in the wash water tank 10 decreases due to evaporation or the like, tap water is appropriately replenished. On the other hand, the sludge which has been deposited or accumulated in the lower part of the thickener 8 is transferred to the intermediate tank 9 and temporarily stored. A series of devices 1 to 9 from the input hopper 1 to the intermediate tank 9 are components of the soil classification unit of the soil purification system S.

  The sludge in the intermediate tank 9 is transferred to the iron content removing device 12. The iron content removing device 12 reduces the content of harmful metals and the like of the sludge by adsorbing and removing the iron-based fine particles from the sludge with a magnetic force. The iron-based fine particles discharged from the iron removal device 12 are supplied to, for example, a steelmaker or the like and used as a steelmaking material. The sludge discharged from the iron removing device 12 is treated by the fine particle washing device 13, the filtering device 14, the clarifying filter 15, the reverse osmosis membrane separation device 16 and the chelating agent regenerating device 17, and harmful metals are eliminated. An almost clean fine particle containing almost no components, etc. and a chelate washing solution are produced. The specific configurations and functions of these devices 13 to 17 will be described in detail later.

Hereinafter, the specific configuration and function of the iron removal device 12 will be described with reference to FIGS. 2 to 6.
As shown in FIG. 2, the iron removing device 12 is characterized in that the iron-based fine particle adsorption is brought into contact with the (large number) of magnetic spheres 20 and the sludge discharged from the thickener 8 (see FIG. 1) as its main components. Device 18, a screen device 19 for separating a mixture (hybrid) of magnetic spheres 20 and sludge discharged from iron-based fine particle adsorption device 18 into magnetic spheres 20 and sludge, and magnetic spheres received from screen device 19 A centrifugal separator 22 removes iron-based fine particles from 20, and a magnetic sphere return device 23 returns magnetic balls 20 discharged from the centrifuge 22 to the iron-based fine particles adsorption device 18.

  Furthermore, the iron content removing device 12 temporarily stores the first to third magnetic spheres for temporarily storing the magnetic spheres 20 supplied to the iron-based fine particle adsorption device 18, the centrifugal separator 22 or the magnetic sphere return device 23, respectively. Containers 24 to 26 and a sludge storage tank 27 for temporarily storing sludge flowing down from the screen device 19 are provided. In the magnetic sphere 20, as will be described later, in the hollow portion of the hollow spherical body 29, a plurality of permanent magnets 30 have the same magnetic poles (N pole or S pole) such that the same magnetic pole (south pole) It is attached (see FIG. 4).

  As shown in FIG. 3, the iron-based fine particle adsorption device 18 is disposed in the air at a substantially overlapping position or the same position in plan view, and arranged in order from the upper side to the lower side in the vertical direction. The first to fourth channel members 100 to 103 are extended. In the following, in order to briefly show the positional relationship in the iron-based fine particle adsorption device 18, for convenience, the side on which the second magnetic sphere storage container 25 is positioned with respect to the extending direction of each channel member 100 to 103 in plan view. (Left side in FIG. 3) is referred to as “left”, and the opposite side, ie, the side on which the first magnetic sphere storage container 24 is located (right side in FIG. 3) is referred to as “right” (see FIG. 2) .

  Although not shown in detail, each channel member 100 to 103 is a bowl-like or groove-like member opened at the top, and the channel formed by the bottom surface and both side surfaces is a mixture of magnetic spheres 20 and sludge. However, it can move (roll or flow) without deviating or falling sideways. The uppermost first channel member 100 is disposed so as to be inclined downward toward the left, and at its left end, the mixture of the magnetic spheres 20 and sludge moved leftward in the first channel member 100 is lowered. The opening 100a is provided to allow free fall. Since the opening 100a is located slightly to the right of the left end of the second channel member 101 immediately below it, the mixture of the magnetic spheres 20 and sludge discharged from the opening 100a is contained in the second channel member 101. Fall or flow down.

  The second channel member 101 is disposed so as to be inclined downward toward the right, and an opening 101a is provided at the right end thereof similarly to the first channel member 100. Since the opening 101a is located slightly to the left of the right end of the third channel member 101 immediately below it, the mixture of magnetic spheres 20 and sludge discharged from the opening 101a is contained in the third channel member 102. Fall or flow down. The third channel member 102 is disposed to be inclined downward toward the left, and an opening 102 a is provided at the left end portion thereof similarly to the first channel member 100. Since the opening 102a is located slightly to the right of the left end of the fourth channel member 103 immediately below it, the mixture of magnetic spheres 20 and sludge discharged from the opening 102a is contained in the fourth channel member 103. Fall or flow down.

  The fourth channel member 103 is disposed so as to be inclined downward toward the right, and an opening 103a is provided at the right end thereof similarly to the first channel member 100. Since the opening 103a is located slightly to the left of the right end of the screen device 19 located below the opening 103a, the mixture of the magnetic spheres 20 and sludge discharged from the opening 103a falls onto the screen of the screen device 19. (See Figure 2). As described above, since the first to fourth linear channel members 100 to 103 are arranged in an inclined manner so as to lead downward in a zigzag shape, the iron-based fine particle adsorption device 18 has a magnetic sphere A zig-zag descending air passage is formed to move the mixture of 20 and sludge. The first to fourth channel members 100 to 103 are formed of a nonmagnetic material or a diamagnetic material so that the magnetic spheres 20 are not adsorbed.

  Thus, the large number of magnetic balls 20 discharged from the first magnetic ball storage container 24 (see FIG. 2) and the sludge discharged from the thickener 8 (see FIG. 1) are supplied near the right end of the first channel member 100. Then, the mixture of the magnetic spheres 20 and the sludge moves (rolls or flows) by gravity in the zigzag-falling air passage formed by the first to fourth channel members 100 to 103 in order. At that time, the iron-based fine particles to which harmful metals and the like in the sludge are adsorbed or to which the harmful metals and the like are attached are attracted to the outer peripheral surface of the magnetic spheres 20 by magnetic force. This reduces the content of harmful metals and the like in the sludge.

  As shown in FIG. 4, in the magnetic sphere 20, a plurality of permanent magnets 30 are generally mounted in the hollow portion of the hollow spherical body 29 so that the respective N poles are directed outward in the spherical body radial direction. It is a thing. The magnetic spheres 20 may be mounted such that the respective S poles of the permanent magnets 30 are directed outward in the radial direction of the spherical body. Specifically, each permanent magnet 30 is inserted into a magnet holding hole 32 formed in the hollow spherical magnet holding member 31. The magnet holding member 31 with the permanent magnet 30 is fitted into the hollow portion of the hollow spherical body 29. In other words, the hollow spherical body 29 is externally fitted to the circumferential surface of the magnet holding member 31, or the circumferential surface of the magnet holding member 31 is covered with the hollow spherical body 29.

  The magnet holding hole 32 formed in the magnet holding member 31 is a tapered hole whose cross-sectional area narrows in the central direction of the magnetic sphere, and the permanent magnet 30 is fitted or aligned with the magnet holding hole 32 (complementary shape Is formed. Therefore, the permanent magnet 30 can be easily attached to the magnet holding member 31 by inserting or inserting the permanent magnet 30 into the magnet holding hole 32 from the outside of the magnet holding member 31. The shape of the end face of the permanent magnet 30 located radially outward in the state of being mounted on the magnet holding member 31 is preferably a curved surface (a part of a spherical surface) that matches the outer peripheral surface of the magnet holding member 31. In this way, the outer peripheral surface of the assembly of the permanent magnet 30 and the magnet holding member 31 becomes spherical, and the assembly and the hollow spherical body 29 can be brought into close contact.

The diameter of the magnetic spheres 20 (i.e., the outer diameter of the hollow spheres 29) is practically, for example, 3 to 5 cm in order to facilitate the transportation of the magnetic spheres 20. Further, the apparent density (or bulk density) of the magnetic spheres 20, that is, the value obtained by dividing the mass of the magnetic spheres 20 by its volume is to reduce the weight of the magnetic spheres 20 as much as possible without floating in the sludge. It is practical to set it in the range of 1.1 to 1.3 g / cm ³ . The apparent density of the magnetic spheres 20 can be adjusted or increased or decreased by appropriately setting the size of the permanent magnet 20 and the number of attached magnets, the volume of the magnet holding member 31 or the hollow portion thereof, etc. It is easy to adjust the apparent density of to 1.1 to 1.3 g / cm ³ .

  The material of the hollow spheres 29 is not particularly limited as long as it has corrosion resistance to sludge and appropriate mechanical strength, but it is practical to use stainless steel or aluminum (or its alloy). The thickness of the hollow spherical body 29 is preferably, for example, about 0.2 to 0.5 mm. If the hollow spheres 29 are formed of a pair of hollow hemispheres that can be screwed together, the manufacture of the magnetic spheres 20 is easy. In this case, the magnetic sphere 20 can be easily assembled by inserting the magnet holding member 31 mounted with the permanent magnet 30 into one hemisphere and screwing the other hemisphere to the hemisphere. The magnetic spheres 20 can be disassembled by canceling the connection. The magnet holding member 31 can be manufactured, for example, by injection molding of a thermoplastic resin (for example, polyethylene, polypropylene or the like). The permanent magnet 20 may be a neodymium magnet having a tapered shape corresponding to the magnet holding hole 32, the large diameter end face being an N pole, and the small diameter end face being an S pole. Note that a neodymium magnet in which the end face on the large diameter side is the S pole and the end face on the small diameter side is the N pole may be used.

  As shown in FIG. 2 again, the screen device 19 receives the mixture of the magnetic spheres 20 and the sludge discharged from the iron-based fine particle adsorption device 18 and separates (screens) the magnetic spheres 20 and the sludge. Although not shown in detail, the screen device 19 is a mesh-like or grid-like screen extending obliquely downward to the second magnetic sphere storage container 25 below the iron-based fine particle adsorption device 18. Have. The opening (opening size) of the screen is such that the magnetic spheres 20 can not pass through.

  When a mixture of magnetic spheres 20 and sludge mixed or dropped from the iron-based fine particle adsorption device 18 onto the screen, the magnetic spheres 20 roll on the inclined screen and the second magnetic sphere storage container Drop into 25 On the other hand, the sludge flows downward through the mesh or opening of the screen and is stored in the sludge reservoir 27. The iron content removing device 12 is provided with a sludge pump 34 for transporting the sludge in the sludge storage tank 27 to the fine particle washing device 13 (see FIG. 1).

  The first magnetic sphere storage container 24 is disposed above the iron-based fine particle adsorption device 18, and the opening degree of the lower end portion (bottom portion) of the first magnetic sphere storage container 24 can be freely adjusted. An opening and closing door 24a is attached. By adjusting the opening degree of the open / close door 24a, the magnetic spheres 20 stored in the first magnetic sphere storage container 24 are discharged downward at a desired passing amount (flow rate) to adsorb the iron-based fine particles It can be supplied to the first channel member 100 of the device 18.

  The second magnetic ball storage container 25 is disposed below the tip (lower end) of the screen device 19 inclined downward, and the magnetic spheres 20 rolled on the screen of the screen device 19 are the tip of the screen. It falls by gravity from this and is accommodated in the 2nd magnetic sphere storage container 25. As shown in FIG. In addition, since the magnetic spheres repel each other by magnetic force (repulsive force), the magnetic spheres 20 do not aggregate in a lump or bunch of grape when moving, and can move smoothly and rapidly (magnetic spheres 20 The same applies when moving within a device or container, or moving to another device or container).

  A centrifugal separator 22 is disposed below the second magnetic sphere storage container 25. The centrifugal separator 22 intermittently and batch-forms the magnetic spheres 20 discharged from the iron-based fine particle adsorption device 18 and temporarily stored in the second magnetic sphere storage container 25 via the screen device 19 (batch Formula (1) is received, and the iron-based fine particles are separated from the magnetic spheres 20 by centrifugal force. At the lower end portion (bottom portion) of the second magnetic sphere storage container 25, an open / close door 25a for allowing the magnetic spheres 20 stored therein to be dropped at any time and supplied to the centrifuge 22 is attached.

  As shown in FIG. 5, the centrifugal separator 22 has a housing 35 which is a substantially cylindrical container, and a central portion of the housing by a bearing device 36 disposed coaxially with the housing 35 in the housing 35 and fixed to the housing 35. And a rotary cylinder 37 rotatably supported about an axis. An upper opening / closing door 37a and a lower opening / closing door 37b that can be opened and closed as needed are attached to the upper end portion and the lower end portion of the rotating cylinder 37, respectively. The circumferential portion (side portion) of the rotary cylinder 37 is formed of a cylindrical mesh member or lattice member provided with a large number of openings with openings that the magnetic spheres 20 can not pass through. The rotary cylinder 37 is rotationally driven by the motor 39 via the gear mechanism 38. In place of the gear mechanism 38, a belt / pulley mechanism may be used. Further, in the housing 35, a hollow-cone-shaped baffle 40 (an umbrella-shaped baffle plate) for receiving and dropping particles of iron-based fine particles flying in a horizontal direction by centrifugal force from the rotating cylinder 37 rotating at high speed is provided. It is arranged.

  As apparent from FIG. 2, the third magnetic sphere storage container 26 is disposed below the centrifuge 22, and when the lower open / close door 37 b (see FIG. 5) is opened when the rotary cylinder 37 is stopped, The magnetic spheres 20 in the cylinder 37 fall by gravity and are stored in the third magnetic sphere storage container 26. At the lower end portion of the third magnetic sphere storage container 26, an open / close door 26a capable of freely adjusting the opening degree is attached. By adjusting the opening degree of the open / close door 26a, the magnetic spheres 20 in the third magnetic sphere storage container 26 can be continuously discharged (dropped) downward at a desired passing amount (flow rate).

  Under the third magnetic sphere storage container 26, the magnetic spheres 20 continuously discharged from the third magnetic sphere storage container 26 are received on a belt 41a (endless belt) and transported in the horizontal direction by the belt 41a. A horizontal belt conveyor 41 is provided to supply the vertical belt conveyor 42. One end (upstream end with respect to the magnetic ball transport direction) of the horizontal belt conveyor 41 is located near the lower end of the third magnetic sphere storage container 26, and the other end (downstream end with respect to the magnetic sphere transport direction) Are located near the lower end of the upright belt conveyor 42. The horizontal belt conveyor 41 and the upright belt conveyor 42 are components of the magnetic ball return device 23.

  The belt 41a is formed of a flexible nonmagnetic material (for example, rubber). And, on both sides of the belt 41a, there are provided side plates (not shown) disposed close to the side of the belt for preventing the magnetic balls 20 on the belt from falling off the side of the belt. . The side plates may not be provided, and ridge-like or bank-like protrusions having an appropriate height (for example, 1 to 2 cm) and extending in the belt extension direction may be integrally formed on both sides of the belt 41a.

  The upright belt conveyor 42 has a position slightly higher than the upper end of the first magnetic sphere storage container 24 directly above the two drive rollers 43a and 43b disposed slightly above the horizontal belt conveyor 41 and the drive rollers 43a and 43b. A ring (endless) of ferromagnetic material (for example, steel, stainless steel, etc.) wound around two driven rollers 44a and 44b, drive rollers 43a and 43b, and driven rollers 44a and 44b. A metal belt 45 and a plurality of idle rollers 46 are provided.

  Here, the drive rollers 43a and 43b are rotationally driven in the counterclockwise direction by a motor (not shown). Along with this, the metal belt 45 travels in a counterclockwise direction between the drive rollers 43a and 43b and the driven rollers 44a and 44b. Here, in the drive roller 43a, a plurality of permanent magnets 49 (see FIG. 6) have an S pole in the roller radial direction in order to assist the movement / adsorption of the magnetic spheres 20 on the belt 41a to the metal belt 45. It is worn so as to face outward.

  When the permanent magnet 30 of the magnetic sphere 20 is mounted such that the S pole is directed outward in the radial direction of the spherical body, the permanent magnet 49 is attached such that the N pole is directed outward in the radial direction of the roller. Ru. The idle roller 46 abuts against the inner surface (rear surface) of the ring-shaped metal belt 45, and regulates the position or traveling path of the metal belt 45 so that the metal belt 45 travels on a predetermined traveling track.

  Since the metal belt 45 is formed of a ferromagnetic material, the magnetic spheres 20 can be attached to the metal belt 45 by magnetic force. The magnetic properties or magnetic strength of the permanent magnet 30 (see FIG. 4) of the magnetic sphere 20 is such that the magnetic sphere 20 is properly spaced below the metal belt 45 (e.g. 5) when the metal belt 45 extends in the horizontal direction. And the magnetic sphere 20 can move upward against gravity and adhere to the lower surface of the metal belt by magnetic force.

  In the horizontal belt conveyor 41, the magnetic ball 20 is magnetically applied to the lower surface of the metal belt between the top of the magnetic ball 20 on the belt 41a and the lower surface of the metal belt at the lower end of the upright belt conveyor 42. It is arranged such that the above-mentioned appropriate spacing can occur. Therefore, the magnetic balls 20 transported to the lower side of the upright belt conveyor 42 by the horizontal belt conveyor 41 adhere to the lower surface of the metal belt by magnetic force in order.

  As shown in FIGS. 6A to 6C, the outer surface of the metal belt 45 of the upright belt conveyor 42 is slightly longer than the diameter of the magnetic spheres 20 in the extending direction (traveling direction) of the metal belt 45. A plurality of (multiple) magnetic ball locking members 47 are attached at intervals so as to extend linearly in the belt width direction. The material of the magnetic ball locking member 47 is not particularly limited as long as it is easy to attach to and remove from the metal belt 45 (for example, screwing) and has durability against collision with the magnetic ball 20. For example, a synthetic resin or an aluminum alloy can be used.

  In the magnetic ball locking member 47, when the metal belt 45 extends in the vertical direction and travels or moves upward, the magnetic ball 20 adhering to the surface of the metal belt 45 by the magnetic force moves downward by gravity or Lock to roll. It is practical to set the height or projecting length of the magnetic ball locking member 47 from the surface of the metal belt to 1/8 to 1/4 of the diameter of the magnetic ball 20. Further, it is practical to set the distance between the magnetic ball locking members 47 adjacent in the extension direction (traveling direction) of the metal belt 45 to 1.2 to 1.5 times the diameter of the magnetic ball 20.

  Thus, the magnetic spheres 20 transported by the horizontal belt conveyor 41 and magnetically attached to the metal belt 45 at or near the lower end of the upright belt conveyor 42 are moved downward by the metal belt 45 which travels in a counterclockwise direction. To the upper end of the upright belt conveyor 42 without moving or rolling.

  As apparent from FIG. 2, near the upper end portion of the upright belt conveyor 42, the magnetic spheres 20 adhering to the metal belt 45 are separated from the metal belt 45 and guided to the first magnetic sphere storage container 24. A guide member 48 is provided. The end on the upright belt conveyor side of the guide member 48 is located near the driven roller 44a, while the end on the first magnetic ball storage container side is located near the upper end of the first magnetic ball storage container 24. . The guide member 48 is inclined downward from the upright belt conveyor side to the first magnetic sphere storage container side. The guide member 48 is formed of a nonmagnetic material.

  In the positional relationship in FIG. 2, the magnetic balls 20 adhering to and moving on the metal belt 45 traveling in the counterclockwise direction collide with or contact the end of the guide member 48 in the vicinity of the driven roller 44a. As a result, the magnetic spheres 20 are separated from the metal belt 45 by the guide members 48, roll on the upper surface of the guide members 48 and fall into the first magnetic sphere storage container 24. That is, the magnetic spheres 20 continuously discharged downward from the third magnetic sphere storage container 26 are the first magnetic spheres by the magnetic sphere return device 23 (horizontal belt conveyor 41, upright belt conveyor 42, guide member 48) It is continuously returned to the storage container 24.

  As described above, the magnetic spheres 20 are, in order, the first magnetic sphere storage container 24, the iron-based fine particle adsorption device 18, the screen device 19, the second magnetic sphere storage container 25, and the centrifuge 22. The third magnetic sphere storage container 26 and the magnetic sphere return device 23 (horizontal belt conveyor 41, upright belt conveyor 42, guide member 48) circulate and move. The seven dashed arrows in FIG. 2 indicate the moving direction of such a magnetic sphere 20. Here, the magnetic spheres 20 move continuously from the first magnetic sphere reservoir 24 to the second magnetic sphere reservoir 25 and intermittently from the second magnetic sphere reservoir 25 to the third magnetic sphere reservoir 26. Or, it moves batchwise and moves continuously from the third magnetic sphere storage container 26 to the first magnetic sphere storage container 24.

  Hereinafter, an example of the operation method of the iron content removal apparatus 12 is demonstrated. The first channel member 100 (see FIG. 3) of the iron-based fine particle adsorption device 18 is continuous with a large number of magnetic spheres 20 that do not substantially adsorb the iron-based fine particle from the first magnetic sphere storage container 24. While being supplied as such, sludge substantially consisting of fine particles (iron fine particles and non-ferrous fine particles) and water is continuously supplied from the intermediate tank 9 (see FIG. 1). Then, in the first to fourth channel members 100 to 103, the mixture of the magnetic spheres 20 and the sludge is moved (rolled or flowed) by gravity in the air passage which is inclined downward in a zigzag manner. At that time, the iron-based fine particles to which harmful metals and the like in the sludge are adsorbed or to which the harmful metals and the like are attached are attracted to the outer peripheral surface of the magnetic spheres 20 by magnetic force. This reduces the content of harmful metals and the like in the sludge.

  The iron-based fine particles are those produced by crushing straw and sand with a mill breaker 3 (see FIG. 1), which is a wet crusher, or those existing before crushing of straw and sand, and any of them Micro-mass such as iron is exposed on the surface, and harmful metals and the like are adsorbed on the micro-mass such as iron which is exposed. In general, small pieces of iron or the like are unevenly distributed or scattered in a gutter and sand, and the proportion of such small pieces is about 2 to 7% by mass. For this reason, at least a part of the fine particle fraction generated by crushing the straw and sand becomes an iron-based fine particle fraction in which fresh iron (that is, harmful metals and the like are not adsorbed) is exposed on the surface.

Iron is a ferromagnetic material (soft magnetic material) and is adsorbed to a magnet. In addition, iron oxides present in the soil substantially include triiron tetraoxide (Fe ₃ O ₄ ), γ-type diiron trioxide (γ-Fe ₂ O ₃ ), and α-type diiron trioxide ( Triiron tetraoxide and γ-type diiron trioxide, which are made of α-Fe ₂ O ₃ ), are ferromagnetic substances (soft magnetic substances) and are adsorbed to a magnet. The α-type diiron trioxide is not magnetized and is not adsorbed to the magnet. For this reason, the iron-based fine particles, in which small lumps such as iron are exposed on the surface, are permanent magnets in the magnetic sphere 20 due to the ferromagnetism (soft magnetism) of iron, triiron tetraoxide or γ type ferric trioxide They are attracted to 30 (see FIG. 4) and are attracted to the outer peripheral surface of the magnetic spheres 20 (hollow spheres 29) by magnetic force.

  Micro-mass such as iron exposed on the surface of iron-based fine particles generated by crushing gravel and sand with mill breaker 3 (see FIG. 1) is unevenly distributed or scattered in the gravel or sand It is produced from small pieces of fresh iron or the like that does not adsorb harmful metals and the like, and is exposed to the surface after crushing and adsorbs harmful metals and the like from washing water around them. Thus, the fine particles discharged from the mill breaker 3 (see FIG. 1) and introduced into the iron-based fine particle adsorption device 18 are iron-based fine particles having a relatively large (or relatively large) adsorption amount of harmful metals and the like. And non-ferrous fine particles having a relatively (or considerably) low adsorption amount of harmful metals and the like.

  And, as described above, since the iron-based fine particles are removed from the sludge in the iron-based fine particles adsorption device 18, the fine particles contained in the sludge discharged from the iron-based fine particles adsorption device 18 are harmful Non-ferrous fine particles with relatively small (or considerably) adsorbed amount of metal etc. are mostly. Therefore, a part or a considerable part of harmful metals and the like contained in the contaminated soil introduced into the soil purification system S is removed in the iron-based fine particle adsorption device 18.

  The mixture of magnetic spheres 20 and sludge discharged downward from the iron-based fine particle adsorption device 18 is introduced into the screen device 19 and the magnetic spheres 20 adsorbing the iron-based fine particles, and the iron-based fine particles It is separated into the removed sludge. Then, the magnetic spheres 20 are stored in the second magnetic sphere storage container 25, and the sludge is stored in the sludge storage tank 27.

  As will be described in detail later, a chelating agent for the sludge (fine particle fraction) discharged from the iron-based fine particle adsorption device 18 and separated by the screen device 19 is a chelating agent by the fine particle washing device 13 (see FIG. 1) The chelating agent is treated by washing and the chelating agent is regenerated by the solid phase adsorbent in the chelating agent regeneration device 17 (see FIG. 1), but as described above, the iron-based fine particle adsorption device 18 Since harmful metals and the like are reduced, the burden of harmful metals and the like on the chelate washing treatment of fine particles (sludge) and the regeneration treatment of the chelating agent is reduced. For this reason, the required amount or use amount of the chelating agent and solid phase adsorbent in the soil purification system S can be reduced, and the processing cost of the soil can be reduced.

  The magnetic spheres 20 adsorbing the iron-based fine particles in the second magnetic sphere storage container 25 are appropriately supplied to the rotating cylinder 37 of the centrifuge 22. Specifically, while the upper opening / closing door 37a is opened and the lower opening / closing door 37b is closed, the opening / closing door 25a is opened, and the second magnetic ball storage container 25 is processed once in the rotary cylinder 37. A minute number of magnetic spheres 20 are supplied. For example, the magnetic spheres 20 are supplied in an amount that occupies 1/3 to 1/2 of the space in the rotary cylinder 37.

  Thereafter, the upper opening / closing door 37a is closed, the motor 39 is activated, and the rotary cylinder 37 is rotated at high speed (for example, 100 to 500 r.p.m. when the radius of the rotary cylinder 37 is 1 m). As a result, the iron-based fine particles adsorbed or attached to the outer peripheral surface of the magnetic sphere 20 are separated from the magnetic sphere 20 by strong centrifugal force (for example, 10 to 100 G), and many meshes of the peripheral wall of the rotating cylinder 37 Or through the hole and jump out to the outside. Here, the rotational speed of the rotating cylinder 37 is such that most of the iron-based fine particles are released from the magnetic balls 20 according to the radius of the rotating cylinder 37, the magnetic force of the magnetic balls 20, the magnetic properties of the iron-based fine particles, etc. It is preferably set to release.

  The iron-based fine particles separated from the magnetic spheres 20 and jumping out of the rotary cylinder 37 collide with the baffle 40 and then fall and accumulate in the bottom of the housing 35. The iron-based fine particles in the housing 35 are appropriately discharged to the outside manually. The removed iron-based fine particles can be used, for example, as an iron-making material. Then, after a predetermined time (for example, 2 to 5 minutes) has elapsed, the rotation of the motor 39 and thus the rotary cylinder 37 is stopped. Thereafter, the lower opening / closing door 37b is opened, and the magnetic spheres 20 from which the iron-based fine particles in the rotary cylinder 37 have been partially removed fall by gravity into the third magnetic sphere storage container 26.

  The magnetic spheres 20 in the third magnetic sphere storage container 26 are continuously supplied onto the belt 41 a of the horizontal belt conveyor 41 and transported by the belt 41 a to the vicinity of the lower end portion of the upright belt conveyor 42. After that, the magnetic balls 20 on the belt 41 a are transported to the upper end portion thereof by the upright belt conveyor 42, and are introduced into the first magnetic ball storage container 24 by the guide member 48. In addition, the supply amount (supply speed) of the magnetic spheres 20 from the third magnetic sphere storage container 26 to the horizontal belt conveyor 41 changes the opening degree of the open / close door 26a to change the horizontal belt conveyor 41 or the upright belt. It is adjusted to be equal to or less than the maximum transport amount of the conveyor 42.

  As shown in FIG. 1 again, the sludge discharged from the iron content removing device 12 (sludge storage tank 27 in FIG. 2) is introduced into the fine particle content cleaning device 13. The fine particle washing device 13 includes a sludge containing non-ferrous fine particles discharged from the iron removing device 12 and washing water, and a chelating agent and water supplied from a chelating agent regeneration device 17 described later. Accept the chelate washing solution, mix and stir them to form a fine particle slurry, and roughly plug flow to ensure a preset residence time (for example, 0.5 to 2 hours) By continuously flowing, harmful metals and the like attached to (adsorbed) fine particles or these ions are captured by the chelating agent. Thereby, harmful metals and the like adsorbed (adhered) on the surface of the fine particles in the fine particle slurry are removed. The ratio of the flow rate of the sludge supplied to the fine particle size washing device 13 to the flow rate of the chelate washing solution is set to, for example, 1: 1.

  As a chelating agent used for the chelate washing solution, for example, EDTA (ethylenediaminetetraacetic acid), or HIDS (3-hydroxy-2,2'-iminodisuccinic acid), IDS (2,2'-iminodisuccinic acid), MGDA (methylglycine) And sodium salts of EDDS (ethylenediaminediacetic acid) or GLDA (L-glutamic acid diacetic acid). Any of these chelating agents can effectively capture (chelate) harmful metals and the like contained in the fine particle slurry or fine particle fraction. Of course, a chelating agent suitable for the treatment is selected or plural kinds of chelating agents are used according to the type of harmful metal and the like contained in the fine particle fraction.

  Hereinafter, the specific configuration and function of the fine particle content washing device 13 will be described with reference to FIGS. 7 (a) to 7 (c). The fine particle content washing apparatus 13 has a storage tank 50 provided with five elongated rectangular parallelepiped or prismatic slurry passages 55 to 59 extending in parallel with each other and formed by dividing by four flat plate-like partition walls 51 to 54. doing. The storage tank 50 may be, for example, an iron rectangular parallelepiped tank installed on the ground, or a concrete rectangular pit. The partition walls 51 to 54 may be formed, for example, by connecting a plurality of iron plates or plastic plates in the extending direction of the slurry passage.

  The two slurry channels adjacent in the slurry channels 55 to 59 have four curves in one communicating portion (FIG. 7A) at one end of the slurry channel longitudinal direction (left and right direction in FIG. 7A and FIG. 7B). Communicate with each other at the portions shown by That is, the partition walls 51 to 54 do not exist in these communicating portions, and the adjacent slurry passages communicate with each other.

  At the bottom of each of the slurry passages 55 to 59, air release pipes 61 to 65 for releasing air into the fine particle slurry and stirring the fine particle slurry are disposed. Each air discharge pipe 61 to 65 extends in the longitudinal direction of the slurry passage, and is a porous pipe in which a plurality of air discharge holes are formed in the bottom of the peripheral wall (lower side) aligned in the longitudinal direction of the slurry passage. Although not shown, it is connected to a compressor or blower that supplies compressed air. When pressurized air is supplied to the air release pipes 61 to 65, the air becomes air bubbles from the air release holes, is released into the fine particle slurry and floats up, and the air bubbles agitate the fine particle slurry by the air bubbles. Be done.

  FIG. 7C shows a cross section of the most upstream slurry passage 55 viewed in the flow direction of the fine particle slurry (the direction indicated by the curved arrow and the straight arrow in FIG. 7A). . As is clear from FIG. 7 (c), the air discharge pipe 61 is disposed in the vicinity of the slurry passage bottom in the vicinity of one side surface of the slurry passage 55. Therefore, the air bubbles discharged from the air discharge pipe 61 rise in the vicinity of this side surface. As a result, a circulating flow is formed in the slurry passage 55 in the direction indicated by the arrow P in a plane perpendicular to the longitudinal direction of the slurry passage, and the fine particle slurry is agitated. The shape, size, volume and the like of the storage tank 50 and the respective slurry passages 55 to 59, and the supply amount of the pressurized air to the air release pipes 61 to 65, etc. The water content is preferably set corresponding to the water content, flow rate, residence time, flow rate, turbulent flow rate (eg, Reynolds number), and the like.

  As apparent from FIG. 1, the fine particle slurry discharged from the fine particle washing device 13 is transferred to the filtering device 14. The filtration unit 14 filters the fines slurry to produce a filter cake with a moisture content of 30 to 40 percent and a filtrate. In addition, as the filtration apparatus 14, a filter press, a vacuum filter, etc. can be used. The filter cake (fine particle content) discharged from the filter device 14 contains almost no harmful metals and the like, and therefore, is used as a culture soil for agriculture, for example, or disposed of in landfills or the like.

  The filtrate or chelate washing solution discharged from the filtration device 14 is transferred to the reverse osmosis membrane separation device 16 after suspended matter or suspended matter (SS) is removed by a clear filter 15 (for example, sand filter). . Although not shown in detail, the reverse osmosis membrane separation device 16 receives the chelate washing solution discharged from the clear filter 15, is pressurized by a high-pressure pump, and is concentrated by the reverse osmosis membrane by which the chelating agent is concentrated. Separate into water and permeate free of chelating agent. Then, the concentrated water is supplied to the chelating agent regenerating apparatus 17, and the permeated water not containing the chelating agent is returned to the thickener 8 by a permeated water transfer means (for example, a pump and a pipeline).

  The reverse osmosis membrane of the reverse osmosis membrane separation device 16 has, for example, a three-layer structure in which a polysulfone supporting layer and a crosslinked aromatic polyamide dense layer are laminated on the surface of a polyester non-woven fabric (100 to 120 μm thick). It can be used. The cross-linked aromatic polyamide dense layer has a large number of pores with a pore diameter of approximately 0.5 to 1.5 nm, and is permeable to water but impermeable to the chelating agent (eg, 0.2 to 0.2 nm) 0.25 μm) semipermeable membrane. Also, the polysulfone support layer is a relatively thick (e.g., 40 to 50 [mu] m) porous membrane to support or protect a very thin crosslinked aromatic polyamide dense layer to prevent its failure.

The reverse osmosis membrane separation device 16 is a spiral type, and includes a plurality of reverse osmosis membrane elements in which a spirally wound reverse osmosis membrane is accommodated in a cylindrical container. For example, it is practical that each reverse osmosis membrane element has a total length of about 1 to 2 m and an outer diameter of about 0.2 to 0.4 m. For example, the effective membrane area of the reverse osmosis membrane in a commercially available reverse osmosis membrane element of this type having a total length of about 1 m and an outer diameter of about 0.2 m (for example, manufactured by Austentec Co., Ltd., Nakatsugawa City, Gifu Prefecture) is It is about 40 m ² . In the case of this reverse osmosis membrane element, when the chelating agent concentration of about 1% by mass is supplied at a pressure of about 1 MPa, the processing amount of the chelating agent is estimated to be about 1.5 m ³ / hr. Therefore, for example, in the case of processing a chelate washing solution at 60 m ^{3 /} h, 40 reverse osmosis membrane elements may be connected in parallel.

  The reverse osmosis membrane separation device 16 is a continuous type, and the operating conditions such as the supply amount and supply pressure (operating pressure) of the chelate cleaning liquid, the discharge amount of concentrated water and permeated water, and the chelating agent concentration ratio of concentrated water It is appropriately set in accordance with the amount of chelating cleaning fluid to be supplied to the cleaning device 13 and the concentration of the chelating agent. For example, the ratio of the flow rate of the sludge supplied to the fine particle washing apparatus 13 to the flow rate of the chelate washing solution is set to 1: 1, and the chelating agent concentration of the fine particle slurry in the fine particle washing apparatus 13 is set to 1% by mass If so, the reverse osmosis membrane separation device 16 generates about 50% of permeate water (chelating agent concentration 0) and about 50% concentrated water (chelating agent concentration about 2% by mass) of the supply amount of the chelate washing solution. Set to Therefore, in the fine particle content washing device 13, the sludge containing no chelating agent and the chelate washing solution having a chelating agent concentration of about 2% by mass are mixed 1: 1, and the chelating agent concentration in the fine particle content washing device 13 is 1 mass. It is maintained at about%.

  The concentrated water, that is, the chelate washing solution discharged from the reverse osmosis membrane separation device 16 is introduced into the chelating agent regeneration device 17 and regenerated. The chelating agent regenerating apparatus 17 has a complexing power higher than that of the chelating agent, and when it comes in contact with a chelating washing solution, it adsorbs or extracts harmful metals and the like in the chelating washing solution, or a small piece on which the solid adsorption material is immobilized. Or having particulate matter, and removing harmful metals and the like from the chelating agent in the chelating washing solution to regenerate the chelating washing solution.

  The solid phase adsorbent is a carrier having a cyclic molecule supported on the carrier, a coordination with a chelate ligand modified to the cyclic molecule and multipoint interaction by hydrogen bond and selectively incorporating ions such as harmful metals. is there. Thereby, harmful metals and the like captured by the chelating agent are released 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 washing liquid (chelating agent), and the chelate washing liquid (chelating agent) is in a state capable of capturing harmful metals and the like again.

  Solid phase adsorbents having higher complexing power than chelating agents are in solid form such as, for example, a gel, and generally, when contacted with an aqueous solution containing a chelating agent capturing a metal, coordination bond with the chelating agent The metal ion has a strong avidity other than the degree of covalent bonding that can release the metal ion from the chelating agent and transfer it to the solid phase adsorbent. Such a solid phase adsorbent, for example, when using EDTA (ethylenediaminetetraacetic acid) as a chelating agent, has a strong binding ability to recover almost 100% of metal ions from an aqueous solution of EDTA having a concentration of 10 mM / l. It is possessed.

  As such a solid phase adsorbent, for example, a solid support of a cyclic molecule on a carrier such as silica gel or resin, and a modification of a chelate ligand to this cyclic molecule, and the like can be mentioned. When such a solid phase adsorbent is used, a plurality of various bonds and interactions such as coordination bonds and hydrogen bonds are caused by adjacent cyclic molecules and chelate ligands, resulting in multipoint interaction and metal ion On the other hand, stronger chemical bonds occur than chelating agents, and metal ions can be selectively incorporated by the nature of cyclic molecules.

  Hereinafter, the specific configuration and function of the chelating agent regenerating apparatus 17 will be described with reference to FIG. The chelating agent regenerating apparatus 17 is provided with a packed tower 70 in which solid adsorbent particles or a packing (solid packing) to which the solid adsorbent is fixed is packed. In addition, the chelating agent regenerating apparatus 17 includes an intermediate storage tank 71 for storing the chelate cleaning liquid (concentrated water) to be regenerated, a cleaning liquid storage tank 72 for storing the regenerated chelate cleaning liquid, and an acid liquid storage tank 73 for storing the acid liquid. , And a water storage tank 74 for storing water.

  Concentrated water discharged from the reverse osmosis membrane separation device 16 (see FIG. 1), that is, a chelate washing solution is temporarily stored in the intermediate storage tank 71. Then, when the chelate washing liquid is regenerated, the pump 76 for transferring the chelate washing liquid stored in the intermediate storage tank 71 to the washing liquid storage tank 72 while transferring the chelate washing liquid stored in the intermediate storage tank 71 to the packing tower 70 Pipelines 77-80 are provided. Further, a pump 81 and a pipeline 82 are provided for supplying the chelate washing solution stored in the washing solution storage tank 72 to the fine particle content washing device 13 (see FIG. 1).

  Further, when the solid phase adsorbent is regenerated to the chelating agent regenerating apparatus 17, the acid solution stored in the acid solution storage tank 73 is transferred to the packing tower 70, while the acid liquid discharged from the packing tower 70 is acid. A pump 83 and a plurality of pipelines 84, 85 for returning to the liquid storage tank 73 are provided. In the chelating agent regenerating apparatus 17, when the solid phase adsorbent regenerated with the acid solution is washed with water, the water stored in the water storage tank 74 is transferred to the packing tower 70, and the water is discharged from the packing tower 70. A pump 86 and a plurality of lines 87, 88 are provided for returning water to the water reservoir 74.

  Pipes 77, 78, 84, 87 for transferring the chelate washing solution, acid solution or water to the packed column 70 are provided with valves 91, 92, 93, 94 for opening and closing the corresponding pipes, respectively. There is. On the other hand, in the conduits 79, 80, 85, 88 for discharging the chelate washing solution, the acid solution or the water from the packed column 70, valves 95, 96, 97, 98 for opening and closing the corresponding conduits are interposed, respectively. It is done. By switching the open / close states of these valves 91 to 98, it is possible to supply or discharge the chelate washing solution, the acid solution or the water to the packed tower 70. The opening and closing of these valves 91 to 98 are automatically controlled by a controller (not shown).

  Hereinafter, an example of the operation method of the chelating agent regenerating apparatus 17 will be described. When the chelating cleaning solution (chelating agent) is regenerated, the valves 91, 92, 95, 96 provided in the conduits 77-80 are opened while the other valves 93, 94, 97, 98 are closed, The pump 76 is operated. As a result, the chelate cleaning liquid in the intermediate storage tank 71 flows in the packed tower 70 and is transferred to the cleaning liquid storage tank 72.

  In the packed tower 70, a chelating cleaning solution containing a chelating agent capturing harmful metals and the like is brought into contact with the solid phase adsorbent (solid phase adsorbent particles). As a result, harmful metals and the like trapped in the chelating agent are released 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 washing solution, and the chelating agent becomes able to capture the harmful metals and the like again, and the chelate washing solution is regenerated.

  While the amount of adsorption of harmful metals and the like in the solid phase adsorbent increases with the regeneration of the chelate washing solution, the adsorption capacity of the solid phase adsorbent has an upper limit. For this reason, when the adsorption amount of harmful metals and the like in the solid phase adsorbent reaches a saturated state or in the vicinity thereof, the solid phase adsorbent is regenerated. That is, the acid solution is flowed into the packed column 70 in a state where the chelate washing solution has been removed, and harmful metals and the like adsorbed on the solid phase adsorbent are removed by the acid solution to regenerate the solid phase adsorbent. Thus, while harmful metals and the like are recovered by the acid solution, the solid phase adsorbent is regenerated to be in a state capable of adsorbing or extracting harmful metals or these ions again.

  When the solid phase adsorbent in the packed column 70 is regenerated with the acid solution, the valves 93, 92, 95, 97 provided in the pipelines 84, 78, 79, 85 are opened, while the other valve 91 is , 94, 96, 98 are closed and the pump 83 is operated. As a result, the acid liquid in the acid liquid storage tank 73 flows through the inside of the packed tower 70 and is refluxed to the acid liquid storage tank 73. Whether or not the harmful metal adsorption amount of the solid phase adsorbent has reached a saturated state or in the vicinity thereof can be determined by detecting the content of the harmful metal or the like in the chelate washing solution discharged from the packed column 70 .

  When the solid phase adsorbent is washed with water after the regeneration of the solid phase adsorbent by the acid solution is finished, the valves 94, 92, 95, 98 interposed in the conduits 87, 78, 79, 88 are opened. , The other valves 91, 93, 96, 97 are closed and the pump 86 is operated. Thus, the water in the water storage tank 74 circulates in the packed tower 70 and returns to the water storage tank 74. Water circulates between the water reservoir 74 and the packed tower 70. At this time, the solid phase adsorbent in the packed column 70 comes in contact with water, and the acid solution adhering to the solid phase adsorbent is washed. After this, regeneration of the chelate washing solution is resumed.

  The chelate washing solution thus regenerated is temporarily stored in the washing solution storage tank 72 and then supplied to the fine particle size washing device 13 (see FIG. 1). That is, the chelate washing solution circulates while repeating purification of fine particles and regeneration of the chelating agent. In addition, the loss of the chelating agent is replenished appropriately.

  As described above, according to the soil remediation system S according to the present invention, clean and reusable straw, sand and fines can be obtained. Further, since the content rate of harmful metals and the like of the sludge discharged from the iron content removing device 12 can be reduced, the load of the harmful metals and the like on the fine particle part washing device 13 and the harmful metals and the like to the chelating agent regenerating device 17 The load can be reduced, the required amount or use amount of the chelating agent and solid phase adsorbent can be reduced, and the cost of treating the soil can be reduced.

  S Soil remediation system, 1 input hopper, 2 mixer, 3 mill breaker (wet crusher), 4 trommel, 5 cyclone, 6 PH adjustment tank, 7 aggregation tank, 8 chicna, 9 intermediate tank, 10 washing water tank, 11 spare Water tank, 12 iron removing device, 13 fine particle washing device, 14 filtration device, 15 clarification filter, 16 reverse osmosis membrane separation device, 17 chelating agent regenerating device, 18 iron fine particle adsorption device, 19 screen device, 20 Magnetic sphere, 21 main body, 21a inclined plate, 22 centrifuge, 23 magnetic sphere return device, 24 first magnetic sphere storage container, 24a opening and closing door, 25 second magnetic sphere storage container, 25a opening and closing door, 26 third magnetic Sphere storage container, 26a opening and closing door, 27 sludge storage tank, 29 hollow spherical body, 30 permanent magnet, 31 magnet holding member, 32 magnet holding hole, 34 slot Pump, 35 housing, 36 bearing device, 37 rotary cylinder, 37a upper opening / closing door, 37b lower opening / closing door, 38 gear mechanism, 39 motor, 40 baffles, 41 horizontal conveyor, 41a belt, 42 upright conveyor, 43a driving roller , 43b drive roller, 44a driven roller, 44b driven roller, 45 metal belt, 46 idle roller, 47 magnetic ball locking member, 48 guide member, 50 storage tank, 51 to 54 partition wall, 55 to 59 slurry passage, 61 to 65 Air discharge pipe, 70 packed tower, 71 intermediate storage tank, 72 washing liquid storage tank, 73 acid liquid storage tank, 74 water storage tank, 76 pump, 77-80 pipe, 81 pump, 82 pipe, 83 pump, 84 pipe, 85 pipe Route, 86 pumps, 87 pipelines, 88 pipelines, 91 to 98 valves, 10 0 first channel member, 101 second channel member, 102 third channel member, 103 fourth channel member.

Claims (3)

What is claimed is: 1. A soil remediation system for remediation of soil contaminated with harmful metals or their compounds, comprising gravel, sand and fine particles,
A mixer for mixing the soil introduced into the soil remediation system with washing water;
Iron or iron oxide that is unevenly distributed or scattered inside the gravel and sand by crushing the gravel and sand in the mixture containing the soil and the washing water discharged from the mixer A wet crusher that produces fines and makes the iron or iron oxide exposed on the surface of the fine irons adsorb or adhere to harmful metals or their compounds in the wash water;
A trommel that separates the straw from the mixture containing the straw, sand, fine particles and washing water, which is discharged from the wet crusher;
A hydrocyclone separating sand from a mixture comprising sand, fines and wash water discharged from the trommel;
A thickener which separates a mixture containing fine particles and wash water discharged from the hydrocyclone into supernatant water and sludge containing fine particles and wash water by sedimentation separation;
An iron removing device for reducing the content of harmful metals or compounds thereof by removing magnetic fine particles from the sludge discharged from the thickener by magnetic attraction;
The sludge discharged from the iron removing device is mixed with a chelate washing solution containing a chelating agent and water to form a fine particle slurry, and the fine particle slurry is flowed to secure a preset residence time. A fine particle washing apparatus for causing a chelating agent to trap harmful metals or compounds thereof adhering to fine particles by
A filtering device for filtering the fine particle slurry discharged from the fine particle washing device to form a filtrate and a filter cake;
A reverse osmosis membrane separation device that separates the filtrate discharged from the filtration device into concentrated water concentrated with a chelating agent and permeated water containing no chelating agent by a reverse osmosis membrane;
A solid phase adsorbent that receives concentrated water discharged from the reverse osmosis membrane separation device and has a higher complexing power than a chelating agent and adsorbs harmful metals or compounds thereof in the concentrated water when contacted with the concentrated water A chelating agent regenerating apparatus for removing harmful metals or compounds thereof from a chelating agent in water and supplying the concentrate as a chelating washing solution to the fine particle size washing apparatus;
A permeated water transfer means for transferring the permeated water discharged from the reverse osmosis membrane separation device to the thickener;
The iron removal device is
A plurality of magnetic spheres in which a plurality of permanent magnets are mounted in the hollow portion of the hollow spherical body so that the same magnetic poles are directed outward in the radial direction of the spherical body, and the sludge discharged from the thickener in a zigzag shape The mixture of magnetic spheres and sludge is received by the upper part of the descending trough-like or groove-like air passage, and the mixture of the magnetic spheres and the sludge is moved downward by gravity in the air passage, An iron-based fine particle adsorption device to be adsorbed on the
A screen device for receiving a mixture of magnetic spheres and sludge discharged from the lower part of the iron-based fine particle adsorption device and separating it into magnetic spheres and sludge;
A centrifugal separator which intermittently receives in a batch system magnetic spheres adsorbing iron-based fine grains discharged from the screen device and separates iron-based fine grains from the magnetic spheres by centrifugal force;
And a magnetic sphere return device for returning the magnetic spheres discharged from the centrifugal separator to the iron-based fine particle adsorption device.   The soil purification system according to claim 1, wherein the air passage is configured by a plurality of linear channel members that are arranged to be inclined downward and to form a zigzag shape. The magnetic ball return device is
A driving roller disposed at a position lower than the lower end of the centrifugal separator, a driven roller disposed above the driving roller at a position higher than the upper end of the ferrous fine particle adsorption device, and the driving roller An endless metal belt made of ferromagnetic metal wound around the driven roller, and a magnetic material attached to the outer surface of the endless metal belt and attracted to the endless metal belt when traveling upwards of the endless metal belt An upright belt conveyor having a magnetic ball locking member for locking down the balls;
Magnetic ball conveying means for conveying the magnetic spheres discharged from the centrifugal separator to the lower end of the upright belt conveyor and causing the endless metal belt to adsorb the magnetic spheres by magnetic force;
A magnetic ball supply means for separating magnetic balls from the endless metal belt at the upper end portion of the upright belt conveyor and supplying the iron-based fine particle adsorption device to the magnetic metal ball suction device. Soil purification system according to 2.

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