JP6544610B1 - Soil purification system - Google Patents

Abstract

[PROBLEMS] To provide a simple and low-cost soil remediation system capable of classifying gravel, sand and fine particles while washing soil with washing water, while reducing harmful metals adsorbed on the fine particles. Do. A soil purification system S includes soil classifying units 1 to 8, an iron content removing device 12, and a chelate cleaning device 14. The soil classification units 1 to 8 crush the gravel and sand in the soil with the mill breaker 3 while washing the soil with washing water, and then use the trummel 4, cyclone 5 and thickener 8 to remove the gravel, sand and fine particles. Classify to The iron removing device 12 uses magnetic balls to adsorb and remove iron-based fine particles from the sludge containing fine particles separated by thickener 8 and washing water by magnetic force. Reduce the rate. The chelate cleaning device 14 removes harmful metals and the like from sludge (fine particles) using a chelate cleaning liquid. [Selected figure] Figure 1

Description

  TECHNICAL FIELD The present invention relates to a soil purification system for purifying a soil which contains straw, sand and fine particles and which is contaminated with harmful metals or compounds thereof.

  In recent years, for example, sites of production facilities using harmful metals such as chromium, lead, cadmium, selenium, mercury, etc. and / or compounds thereof or ions thereof (hereinafter collectively referred to as "harmful metals etc.") as raw materials or materials Or the soil pollution in the neighboring land due to soil pollution or illegal dumping of industrial waste containing harmful metals etc. occurs frequently. 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 inventor of the present application has already classified the harmful metal-contaminated soil with washing water, classified it into gravel, sand and fine particles, and then washed the fine particles with a chelating cleaning solution containing a chelating agent. Various soil purification facilities (contaminated soil purification devices) have been proposed which are designed to remove harmful metals and the like from fine grains (see Patent Documents 1 and 2, for example).

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 processor, 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, , 500-600 tons per day on a dry basis). 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 increases as the content of the fine particles of harmful metals and the like increases. When fine particles are washed with a washing solution containing chemicals other than chelating agents to remove harmful metals etc. (chemical treatment), or harmful metals etc. are removed by physicochemical treatment using adsorbents etc. The same problem arises in the case.

  The present invention was 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 can be classified into fine particles, and harmful metals etc. adsorbed or attached to the separated fine particles can be removed, or at least the content rate of harmful metals etc. of fine particles etc. The problem to be solved is to provide a soil purification system with lower treatment cost that can reduce the rate.

  According to the present invention, which was made to solve the above problems, a soil which contains soot, sand and fine particles and which purifies soil contaminated with harmful metals and the like (toxic metals and / or compounds thereof) or these ions The purification system comprises a mixer, a wet crusher, a trommel, a hydrocyclone, a thickener, an iron removal device, a filter, a chelate cleaning device, and a filtrate return means.

  Here, the mixer mixes the soil introduced into the soil purification system with the washing water. A wet crusher is an iron or iron oxide (hereinafter referred to as “localized” or “localized” that is unevenly distributed or scattered within the gravel and sand by crushing the gravel and sand in the mixture containing the soil and wash water discharged from the mixer. Collects iron-based fine particles exposed on the surface, and adsorbs or adheres harmful metals etc. in cleaning water to iron etc. exposed on the surface of iron-based fine particles. 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 (fine particle fraction) by magnetically removing the iron-based fine particle fraction from the sludge discharged from the thickener. The filter receives the sludge containing fines and water from which the iron-based fines have been removed by the iron removing device, filters and separates into a filter cake containing fines and a filtrate. The chelating agent washing device cleans the filter cake separated by the filter with a chelating agent washing solution containing a chelating agent and water to remove harmful metals and the like remaining in fine particles. The filtrate return means returns the filtrate separated by the filter to the thickener.

  In the soil purification system according to the present invention, the iron removal device includes an iron removal device having an iron-based fine particle adsorption device, a screen device, a centrifuge, and a magnetic sphere return device. In the iron-based fine particle adsorption device, the iron-based fine particle adsorption device is such that a plurality of permanent magnets have the same magnetic pole (N pole or S pole) in the hollow portion of the hollow spherical body outward in the spherical body radial direction The plurality of (multiple) magnetic balls mounted as such and the sludge discharged from the thickener are received in the upper part of a trough-like or groove-like air passage which descends in a zigzag manner, and the mixture of magnetic balls and sludge is In the air passage, it is moved downward by gravity, and at the time of movement, iron-based fine particles in the sludge are attracted to 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. In this case, the upright belt conveyor includes a drive 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 drive 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 And a magnetic ball locking member for locking the lowering of the magnetic ball. The magnetic ball conveying means conveys the magnetic spheres discharged from the centrifugal separator to the lower end of the upright belt conveyor and causes the endless metal belt to attract the magnetic spheres by magnetic force. The magnetic sphere supply means separates the magnetic spheres from the endless metal belt at the upper end of the upright belt conveyor and supplies it to 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, in the soil remediation system according to the present invention, the gravel and / or sand is crushed by the wet crusher to generate fine particles, and among these fine particles, uneven distribution or point in the weir or sand Fine particles containing a large amount of iron and other fine particles are iron-based fine particles, and iron and the like exposed on the surface of these iron-based fine particles extend from a wet crusher to an iron content removing device It 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 removing device, when a mixture of magnetic spheres and sludge is moved downward by gravity in a trough-like or groove-like air passage which descends in a zigzag manner, the iron-based fine particles in the sludge are reduced. It is attracted to the magnetic sphere by the 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, when the sludge discharged from the iron removal device is chemically treated by the chelate cleaning device, the load of harmful metals and the like on the chelate cleaning device can be reduced. As a result, the necessary amount or use amount of a chemical agent such as a chelating agent can be reduced, and the treatment 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 or treatment agents, 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.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows schematic structure of the soil purification system which concerns on Embodiment 1 of this 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. It is a block diagram which shows schematic structure of the chelate washing apparatus which is a component of a soil purification system. It is a typical elevation view which shows the structure of the mixing and dispersing apparatus which makes a part of chelate washing | cleaning apparatus. (A) is a schematic plan view of the fine particle size washing apparatus which forms a part of the chelate washing apparatus, and (b) is a sectional view taken along line A-A of the fine particle size washing apparatus shown in (a), (C) is an elevational cross-sectional view of one slurry passage of the fine particle content washing device. It is a block diagram which shows schematic structure of the soil purification system which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be specifically described with reference to the attached drawings.
(Embodiment 1)
As shown in FIG. 1, in the soil remediation system S according to Embodiment 1 of the present invention, it is collected by excavating the ground contaminated with harmful metals and the like (toxic metals and / or their compounds, or ions thereof) Soil (contaminated soil) is received by 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 input 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, one having a particle diameter of 2 to 75 mm), a sand (for example, one having a particle diameter of 0.075 to 2 mm) and a fine particle fraction (for example, a particle diameter of 0.075 mm or less) And, optionally, stones (eg, those having 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 the micro-mass of iron or the like (iron and / or iron oxide) present inside or unevenly distributed or scattered inside 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, part or most of the harmful metals and the like 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. There is no proposal for a method for treating harmful metals and the like in which harmful metals and the like are adsorbed on the exposed micro-mass (iron-based fine particles) such as iron.

  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 so 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 straw and sand, the straw separated by the trommel 4 is clean, and is used, for example, as an aggregate for concrete be able to. 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.

  Soil particles contained in the receiving tank of the trommel 4 and having a particle diameter of less than 2 mm, that is, a soil / water mixture containing sand and fine particles and washing water, are introduced into the 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 mixture of sand and water discharged from the lower end 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 solution (PAC), 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.

  The water containing fine particles in the coagulation tank 7 is introduced into the thickener 8. 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 as washing water. 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. In addition, when the wash water stored by the wash water tank 10 reduces by evaporation etc., tap water is replenished suitably. On the other hand, the sludge deposited under 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 removal device 12 by a sludge pump or the like (not shown). 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 specific configuration and function of the iron removal device 12 will be described in detail later.

  The sludge discharged from the iron removal device 12 is introduced into the filter press 13 and dewatered to form a filtrate and a cake. The filtrate is then returned to the thickener 8. On the other hand, the cake is transferred to the chelate cleaning device 14 to remove harmful metals and the like remaining in the fine particles (non-ferrous fine particles). Here, if the content rate of the harmful metal or the like in the fine particles contained in the cake is within the standard, the cake is disposed of by landfilling or the like without being transferred to the chelate cleaning device 14. In place of the filter press 13, another filter, such as a vacuum filter, may be used. The specific configuration and function of the chelate cleaning device 14 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 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 includes the magnetic spheres 20 and the like. A zigzag descending air passage is formed to move the sludge mixture. 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 filter press 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.

  The sludge (fine particle fraction) discharged from the iron-based fine particle adsorption device 18 and separated by the screen device 19 is subjected to a filtration treatment by the filter press 13 and the chelate washing device 14 (FIG. 1) The chelate washing treatment with a chelating agent is applied in the reference), but since the harmful metal etc. in the sludge is reduced by the iron-based fine particle adsorption device 18 as described above, the chelate washing treatment or the like of the fine particle (sludge) The burden of harmful metals and the like on the regeneration treatment of the chelating agent is reduced. For this reason, the required amount or use amount of the chelating agent in the soil purification system S can be reduced, and the treatment 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.

  Hereinafter, the configuration and function of the chelate cleaning device 14 will be described. When the content rate of harmful metals and the like of the cake discharged from the filter press 13 is lower than a predetermined regulation value in disposal by landfill, reuse, etc., it is not necessary or necessary to use the chelate cleaning device 14 .

  First, the general configuration and function of the cleaning device 14 will be described with reference to FIG. In the chelate cleaning device 14, first, the cake (filter cake) discharged from the filter press 13 (see FIG. 1) and the chelate cleaning solution containing the chelating agent in the cleaning solution storage tank 56 are continuously supplied to the mixing and dispersing device 51. Be done. Then, the mixing and dispersing device 51 mixes the cake and the chelate washing solution, and fine particles or small particles in the chelate washing solution (for example, the particle diameter is about several 0.1 to 0.5 mm, or 0.1 Particles of about 1 mm (approximately 1 mm in size) are dispersed almost uniformly (suspended) to form a fine particle slurry.

  The fine particle slurry generated by the mixing and dispersing device 51 is transferred to the fine particle washing device 52. The fine particle content cleaning device 52 flows the fine particle content slurry by plug flow (plug flow) so as to secure a preset residence time (for example, 0.5 to 2 hours) while stirring. The harmful metals and the like attached to the fine particles are released and captured by the chelating agent in the chelating solution. Thereby, harmful metals and the like adsorbed (adhered) on the surface of the fine particles in the fine particle slurry are removed.

  Here, as a chelating agent used for the chelating washing solution, for example, EDTA (ethylenediaminetetraacetic acid), or HIDS (3-hydroxy-2,2'-iminodisuccinic acid), IDS (2,2'-iminodisuccinic acid), MGDA (Methylglycinediacetic acid), EDDS (ethylenediaminediacetic acid) or sodium salt of GLDA (L-glutamic acid diacetic acid), and the like. 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.

  The fine particle slurry discharged from the fine particle washing device 52 is transferred to the filtering device 53. The filtration unit 53 filters the fine particle slurry to produce a cake with a moisture content of 30 to 40 percent (filter cake) and a filtrate. In addition, as such a filtration apparatus 53, a filter press, a vacuum filter, etc. can be used. The filter cake (fine particle content) discharged from the filter device 53 contains almost no harmful metals and the like.

  The filtrate discharged from the filtering device 53, that is, the chelate washing solution is introduced into the washing solution regeneration unit 54. The cleaning liquid regeneration unit 54 includes a cleaning liquid regeneration device 55, a cleaning liquid storage tank 56, an acid liquid storage tank 57, and a water storage tank 58. Here, although not shown in detail, the cleaning solution regenerating apparatus 55 has higher complexing power than the chelating agent, and when it comes in contact with the chelating cleaning solution (filtrate) discharged from the filtering apparatus 53, harmful metals etc. in the chelating cleaning solution Solid adsorbent adsorbing or extracting solid particles or packings (pieces or particles) on which the solid adsorbents are immobilized are retained inside, and chelating agents in the chelate washing liquid flowing in the gaps of the packings harmful metals etc. Is a packed tower type device for removing the

  In the cleaning solution regenerating apparatus 55, a chelating cleaning solution containing a chelating agent capturing harmful metals and the like is brought into contact with a solid phase adsorbent having higher complexing power than the chelating agent. 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.

  The chelate washing solution thus regenerated by the washing solution regenerating apparatus 55 is temporarily stored in the washing solution storage tank 56, and then returned to the mixing and dispersing apparatus 51 by the washing solution reflux mechanism (not shown in detail). That is, the chelate washing solution circulates in the chelate washing device 14 while repeating purification of fine particles and regeneration of the chelating agent. In addition, the loss of the chelating agent is replenished appropriately.

  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.

  The amount of adsorption of harmful metals and the like in the solid phase adsorbent increases with time as the chelate washing solution is regenerated, but the amount of adsorption of harmful metals and the like in the solid phase adsorbent has an upper limit. Therefore, 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 by the solid phase adsorbent regeneration mechanism (not shown in detail). That is, in the solid phase adsorbent regeneration mechanism, the acid solution in the acid solution storage tank 57 is flowed to the cleaning solution regeneration unit 55 in a state where the chelate washing solution is removed, and harmful metals and the like adsorbed on the solid phase adsorbent are treated with the acid solution. Remove and regenerate solid phase adsorbent. At this time, the acid liquid circulates between the acid liquid storage tank 57 and the cleaning liquid regenerating apparatus 55. 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 harmful metals and the like again.

  The solid phase adsorbent in the washing liquid regenerating apparatus 55 is regenerated by the acid solution and then washed with water by a water washing mechanism (not shown in detail) to remove the acid liquid adhering to the solid phase adsorbent. At this time, water used for water washing of the solid phase adsorbent circulates and flows between the water storage tank 58 and the cleaning liquid regenerating apparatus 55. The detailed configuration of the cleaning solution regenerating unit 54 and the operation method thereof are disclosed in Japanese Patent No. 6264592 (see FIG. 3 and paragraphs [0035] to [0045]) and Japanese Patent No. 6264593, with the applicant of the present application as the patentee. (See FIG. 3 and paragraphs [0035] to [0045]) and the like.

Hereinafter, the specific configuration and function of the chelate cleaning device 14 will be described.
First, the specific configuration and function of the mixing and dispersing device 51 which is a component of the chelate cleaning device 14 will be described with reference to FIG. The mixing and dispersing device 51 continuously mixes the cake (fine particles) discharged from the filter press 13 (see FIG. 1) and the chelate washing solution, and the fine particles are dispersed in the chelating washing solution. Generate a slurry. Specifically, the mixing and dispersing device 51 pre-mixes the crusher 61 for crushing the cake (fine particles) discharged from the filter press 13, the cake pieces crushed by the crusher 61, and the chelate washing solution. The mixture produced by the premixing tank 62 and the premixing tank 62 is stirred to chelate cake pieces (for example, particles having a particle size of about 0.1 to 0.5 mm, or about 0.1 to 1 mm). And a line mixer 63 for dispersing or suspending in the washing solution.

  Then, in the mixing and dispersing device 51, the cake discharged from the filter press 13 is supplied to the crusher 61, and the cake is rotated by the blade 61a rotating at a high speed, for example, a large number of particles of several mm (for example, 1 to 5 mm). It is broken up into cake pieces. On the other hand, to the crusher 61, the chelate cleaning solution in the chelating solution storage tank 64 is supplied by the pump 65 through the conduit 66. The chelate cleaning liquid is appropriately supplied to the chelate cleaning liquid storage tank 64 from the cleaning liquid storage tank 56 (see FIG. 7). Although not shown in detail, the chelate washing solution is sprayed or supplied to a large number of cake pieces immediately after being broken down by the blade 61a to prevent the cake pieces from adhering to each other. In addition, as such a crusher 61, for example, a "dewatered cake crusher" related to Taiyo Kiko Co., Ltd. or a "dewatered cake recycling apparatus" related to Futosha Co., Ltd. can be used. In the case of using a commercially available crusher, it is necessary to provide a mechanism for injecting or supplying a chelate washing solution to a large number of cake pieces immediately after being crushed.

  The chelate solution and cake pieces in the crusher 61 are transferred to the premix tank 62. The chelate washing solution and the cake pieces in the premix tank 62 are stirred and premixed by a stirrer 67 which is rotationally driven by a motor. Then, the mixture of the chelate washing solution and the cake pieces in the premix tank 62 is transferred by the pump 68 to the line mixer 63 through the pipe line 69. The line mixer 63 is a flow-through type mixer in which a blade rotationally driven at a very high speed by a motor is disposed in a horizontally-arranged substantially cylindrical stirring chamber and very vigorously stirs the chelate washing solution and the cake pieces. The cake or fine particles in the chelate washing solution (eg, particles having a particle size of about 0.1 to 0.5 mm, or about 0.1 to 1 mm) are almost uniformly dispersed (suspended). A fine particle size slurry is produced. The fine particle slurry is transferred to the fine particle washing device 52 (see FIG. 7). As such a line mixer 63, for example, a "Satake multi line mixer" or the like according to Satake Chemical Engineering Co., Ltd. can be used.

  Hereinafter, with reference to FIGS. 9A to 9C, the specific configuration and function of the fine particle content washing device 52 which is a component of the chelate washing device 14 will be described. The fine particle content washing device 52 adsorbs (adheres to the fine particle content) by flowing the fine particle content slurry produced by the mixing and dispersing device 51 by plug flow so as to secure a preset residence time while stirring. And the like) are released from the fine particles and trapped by the chelating agent.

  The fine particle content cleaning device 52 has a storage tank 70 provided with five elongated rectangular parallelepiped or prismatic slurry passages 75 to 79 extending in parallel with each other and formed by dividing by four flat plate-like partition walls 71 to 74. doing. The storage tank 70 may be, for example, an iron rectangular parallelepiped shaped tank installed on the ground, or may be a concrete rectangular parallelepiped shaped pit. Further, the partition walls 71 to 74 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 75 to 79 have four curves in one communicating portion (FIG. 9A) at one end of the slurry channel longitudinal direction (left and right direction in FIG. 9A and FIG. 9B). Communicate with each other at the portions shown by That is, the partition walls 71 to 74 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 75 to 79, air release pipes 81 to 85 for releasing air into the fine particle slurry and stirring the fine particle slurry are disposed. Each air discharge pipe 81 to 85 extends in the longitudinal direction of the slurry channel, 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 channel. 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 81 to 85, 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. 9C shows a cross section of the most upstream slurry passage 75 as viewed in the flow direction of the fine particle slurry (the direction indicated by the curved arrow and the straight arrow in FIG. 9A). . As is clear from FIG. 9 (c), the air discharge pipe 81 is disposed in the vicinity of the slurry passage bottom in the vicinity of one side surface of the slurry passage 75. Therefore, the air bubbles released from the air release pipe 81 rise in the vicinity of this side surface. As a result, a circulating flow is formed in the slurry passage 75 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 70 and the respective slurry passages 75 to 79, and the supply amount of the pressurized air to the air discharge pipes 81 to 85, 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.

  In the soil purification system S according to the first embodiment, harmful metals and the like are hardly adsorbed by the moss and sand during the washing and classification of the contaminated soil by the washing water, and are concentrated and adsorbed to the fine particles, It is possible to obtain clean and reusable straw and sand. Then, in the soil purification system S, the mill breaker 3 crushes the gravel and the sand to generate an iron-based fine particle fraction and a non-ferrous-based fine particle fraction. Therefore, the iron-based fine particle fraction existing before crushing and the iron-based fine particle fraction generated by crushing are introduced to the iron content removing device 12, and all of these iron-based fine particle fractions are considerably large ( In comparison with non-ferrous fine particles, it adsorbs harmful metals etc.).

  Then, in the iron content removing device 12, the magnetic spheres 20 in the first to fourth channel members 100 to 104 (refer to FIG. 3) of the iron based fine particle content adsorption device 18 are iron based thin particles having a large adsorption amount of harmful metals and the like. Since the particulate matter is removed from the sludge, the content or retention rate of harmful metals and the like of the sludge can be reduced. Therefore, it is possible to reduce the load of harmful metals and the like on the chelate cleaning device 14 that performs the chelate cleaning process on the sludge discharged from the iron content removing device 12. In addition, depending on the property of the soil, the content rate of harmful metals and the like can be reduced to such an extent that dumping or landfill treatment is possible.

  Since the content rate of harmful metals and the like of the sludge discharged from the iron removing device 12 is thus reduced, when the cake discharged from the filter press 13 for filtering the sludge is chelate-cleaned by the chelate cleaning device 14, The amount of use or necessary amount of chelating agent and solid phase adsorbent can be reduced, and the cost of treating the soil can be reduced. In addition, since the mill breaker 3 and the iron content removal apparatus 12 are of a machine structure which performs physical processing and do not use special chemicals for processing harmful metals and the like, the operation cost is very low.

Second Embodiment
Hereinafter, soil purification system S 'which concerns on Embodiment 2 of this invention is demonstrated, referring FIG. However, the soil purification system S ′ according to the second embodiment and the soil purification system S according to the first embodiment shown in FIGS. 1 to 9 are common in many respects. So, below, in order to avoid duplication of explanation, difference with soil purification system S in soil purification system S 'is mainly explained. In addition, in the component of soil purification system S 'which concerns on Embodiment 2, the same reference number as Embodiment 1 is attached | subjected to what is common in the component of soil purification system S which concerns on Embodiment 1. FIG.

  Although soil purification system S 'which concerns on Embodiment 2 abbreviate | omits the description of the one part in FIG. 10, like the soil purification system S which concerns on Embodiment 1, it extends from the input hopper 1 to the intermediate tank 9 A series of apparatuses 1 to 9, a flush water storage tank 10, a spare water tank 11, and an iron removal apparatus 12 are provided. However, the soil purification system S 'does not include the filter press 13 and the chelate cleaning device 14 in the first embodiment. And soil purification system S 'is provided with the fine particle content washing apparatus 91, the filtration apparatus 92, the clarification filter 93, the reverse osmosis membrane separation apparatus 94 (RO separation apparatus), and the chelating agent regenerating apparatus 95. There is.

  Although not shown in detail, the fine particle washing apparatus 91 receives sludge containing non-ferrous fine particles discharged from the iron removing apparatus 12 and washing water, and a chelating washing solution containing a chelating agent and water. These are mixed and stirred to form a fine particle slurry, and the nonferrous fine particles are adsorbed (adhered) by continuously flowing so as to secure a preset residence time. The harmful metal or the like is released and captured by the chelating agent, or the harmful metal or the like present in water is captured by the chelating agent. As such a fine particle content washing device 91, for example, the fine particle content washing device 52 (see FIGS. 9A to 9C) according to the first embodiment can be used. The ratio of the flow rate of the sludge supplied to the fine particle size washing device 91 to the flow rate of the chelate washing solution is set to, for example, 1: 1. In addition, the chelating agent to be used is the same as that of Embodiment 1.

  The fine particle slurry discharged from the fine particle washing device 91 is transferred to the filtering device 92. The filtration device 92 filters the fines slurry to produce a cake with a moisture content of 30 to 40 percent (filter cake) and a filtrate. In addition, as the filtration apparatus 92, a filter press, a vacuum filter, etc. can be used. The cake (fine particle) discharged from the filtering device 92 hardly contains harmful metals and the like.

  The filtrate or chelate washing solution discharged from the filtration device 92 is pressure-fed to the reverse osmosis membrane separation device 94 after suspended matter or suspended matter (SS) is removed by a clear filter 93 (for example, sand filter). . Although not shown in detail, the reverse osmosis membrane separation device 94 receives the chelate washing solution discharged from the clear filter 93, and the reverse osmosis membrane does not contain the concentrated water in which the chelating agent is concentrated and the chelating agent. Separates to permeate water.

  The reverse osmosis membrane of the reverse osmosis membrane separator 94 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 94 is of 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 94 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 91 and the concentration of the chelating agent. For example, the ratio of the flow rate of the sludge supplied to the fine particle washing device 91 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 device 91 is set to 1% by mass If so, the reverse osmosis membrane separation device 94 generates about 50% of the permeated 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 91, 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 91 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 94 is introduced into the chelating agent regeneration device 95 and regenerated. That is, 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. As such a chelating agent regenerating apparatus 95, for example, the cleaning fluid regenerating unit 54 (see FIG. 7) in the first embodiment can be used.

  According to the soil purification system S ′ according to the second embodiment, similar to the soil purification system S according to the first embodiment, clean and reusable straw and sand can be obtained, and are discharged from the iron removing device 12 The content of harmful metals etc. in the sludge can be reduced. Thus, since the content rate of harmful metals and the like of the sludge discharged from the iron content removing device 12 is reduced, it is possible to reduce the use amount or necessary amount of the chelating agent in the fine particle content cleaning device 91, The amount of use or necessary amount of solid phase adsorbent in the chelating agent regenerating apparatus 95 can be reduced, and the processing cost of the soil can be reduced.

  S soil purification system (embodiment 1), S 'soil purification system (embodiment 2), 1 input hopper, 2 mixer, 3 mill breaker (wet crusher), 4 trommel, 5 cyclone, 6 PH adjustment tank, 7 Coagulation tank, 8 chicna, 9 intermediate tank, 10 washing water tank, 11 spare water tank, 12 iron content removing device, 13 filter press, 14 chelate washing device, 18 iron based fine particle adsorption device, 19 screen device, 20 magnetic sphere, 21 Body part, 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 sludge port Pumps, 35 housings, 36 bearing devices, 37 rotating cylinders, 37a upper opening and closing doors, 37b lower opening and closing doors, 38 gear mechanisms, 39 motors, 40 baffles, 41 horizontal conveyors, 41a belts, 42 upright conveyors, 43a driving rollers , 43b drive roller, 44a driven roller, 44b driven roller, 45 metal belt, 46 idle roller, 47 magnetic ball locking member, 48 guide member, 49 permanent magnet, 51 mixing and dispersing device, 52 fine particle washing device, 53 filtration Equipment, 54 cleaning fluid regeneration unit, 55 cleaning fluid regeneration device, 56 cleaning fluid storage tank, 57 acid solution storage tank, 58 water storage tank, 61 disintegrator, 61a blade, 62 premixing tank, 63 line mixer, 64 chelate cleaning fluid storage tank, 65 pump, 66 Pipeline, 67 stirrer, 68 pump, 69 pipeline, 7 0 Reservoir, 71-74 partition wall, 75-79 slurry passage, 81-85 air discharge pipe, 91 fine particle washing device, 92 filtration device, 93 clarification filter, 94 reverse osmosis separation device, 95 chelating agent regeneration device, 100 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;
A filter that receives sludge containing fine particles and water from which iron-based fine particles have been removed by the iron content removing device, filters the sludge, and separates into a filter cake containing fine particles and a filtrate;
A chelate washing device for washing the filter cake separated by the filter with a chelate washing solution containing a chelating agent and water to remove harmful metals or compounds thereof remaining in fine particles;
And a filtrate return means for returning the filtrate separated by the filter 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.

Images