JP4256505B2 - How to treat dredged soil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating dredged soil that can be reused by dredging sediment deposited on a bay coast, an outflow river, etc., and classifying it according to the particle size of stones, sand, fine particles and the like.
[0002]
[Prior art]
Conventionally, sediment deposited on bays and outflowing rivers may cause obstruction of the channel and decrease in river flow, so it is provided in advance after being dredged by dredgers equipped with dredgers (also called scavengers). It was put into a sedimentation basin, treated by sun drying or cement treatment to reduce the volume and temporarily piled up, and then landed in a disposal site. In addition, even when it was directly put into the settling basin, volume reduction such as draining water was attempted.
However, in the above conventional treatment method, salinity remains in dredged sand and affects vegetation, so that there is a limit to use as landfill. In addition, sedimentation of spilled sediments in the bays and rivers is a continuous occurrence, and dredging work must be performed almost regularly. Therefore, the disposal amount of dredged soil has become enormous, and it has been difficult to secure sedimentation basins and disposal sites.
[0003]
Therefore, after refining dredged sediments (hereinafter referred to as landfilled sediments), a lot of vibration sieves are used, and some are classified into gravel, sand, silt, etc. using liquid cyclones. A soil treatment system has been proposed (Japanese Patent Laid-Open No. 8-164363). This is done by using a rotary crusher that pulverizes particles such as aggregated lump or sand lump in the above-mentioned landfill sand into individual particles without crushing the individual particles such as sand. After the earth and sand are refined, the above-mentioned refined dredged sand is classified by a plurality of vibrating sieves, and the fine particles that have passed through the final stage sieve are further classified by a liquid cyclone.
3A and 3B are views showing the configuration of the rotary crusher 10, wherein FIG. 3A is a side view, and FIG. 3B is a cross-sectional view taken along line AA. The rotary crusher 10 is attached to the inner peripheral surface along the axial direction, and is attached to the outer peripheral surface along the axial direction with the cylindrical rotary drum 11 having a plurality of outer blades 11W protruding in the center direction. A rotor 12 having a plurality of inner blades 12W projecting in the center direction and eccentrically mounted inside the rotary drum 11, and an annular gear 11a provided on the outer periphery of the rotary drum 11 by a motor 13. The rotating shaft 12a attached to the rotor 12 is rotated in the opposite directions by the drive mechanism 12b, respectively, and the compression and rubbing force is applied to the dredged sand put in the rotary crusher 10 while adding water, The dredged material is pulverized without being crushed.
[0004]
[Problems to be solved by the invention]
However, since the dredged soil processing system using the conventional rotary crusher 10 uses a lot of vibration sieves, the processing speed is slow and the equipment becomes complicated. This is a treatment system for the sewage, so that there is a problem that dredged soil with a lot of water drawn directly from the ocean cannot be treated. This is because, in the rotary crusher 10, the amount of treated water to be added is limited in order to apply the compressing and rubbing force to the dredged sand put into the treatment gap. Incidentally, in the above-mentioned landfill earth and sand, the contained water is about 40% or less of the whole, whereas the pumped up porridge is about 90% moisture.
Against this background, establishment of dredging sand salinity removal technology and volume reduction technology by recycling is desired.
[0005]
The present invention has been made in view of the conventional problems, and removes salt from the dredged sediment from the gulf and outflow rivers, and efficiently classifies and recycles dredged soil into gravel, sand, fine particles, etc. An object of the present invention is to provide a method for treating dredged soil that can be used.
[0006]
[Means for Solving the Problems]
Processing method of dredged material according to claim 1 of the present invention, hydrolysis Gulf or outflow river directly from pumped dredged material and sends to the feed sump, the dredged material which has been previously deposited in grain refining means However, the finely divided material is sent to the feed sump, and the soot stored in the feed sump is put into a liquid cyclone for classification , and the solid matter precipitated at the bottom of the liquid cyclone is washed with water to remove the salt. In addition to taking out the solid matter, the treated water containing the fine particles at the top of the hydrocyclone is returned to the feed sump, and the supernatant of the feed sump and the wash water from which the solid matter has been washed are sent to a thickener tank to be solidified. It is characterized by taking out the fine particles in the cake from which the salt has been removed by liquid separation .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a processing flow showing a continuous processing system for dredged sand according to the present embodiment. The continuous treatment system according to the present embodiment includes a dredge robot 1 that pumps up and transports sediment deposited on the shores, outflow rivers, and the like, a feed sump 2 that stores dredged material from the dredge robot 1, and the treated water. A plurality of liquid cyclones 3 that float and separate light particles having a small particle diameter (hereinafter referred to as “fine particles”) out of the input material, and a precipitate composed of solids such as gravel and sand that have settled at the bottom of each liquid cyclone 3. A spigot tank 4 for temporarily storing things, a vibrating dewatering screen (aqua screen) 5 for cleaning the sediment in the spigot tank 4 and separating gravel, sand, etc. from the sediment, and an upper portion of each hydrocyclone 3 A thickener tank 6 for separating fine particles from the treated water containing the fine particles and the separated silt, and a deposit in the thickener tank 6 temporarily. A slurry tank 7 to built, and a filter press 8 for producing a dewatered cake from a slurry stored in the slurry tank 7.
[0012]
In addition, since the above-mentioned continuous processing system simultaneously processes dredged sand dredged from the gulf or outflow river and accumulated dredged sand (hereinafter referred to as landfilled sand), the conventional rotary crusher described above is used. 10 and without causing the particles such as gravel and sand of the above-mentioned clay sand to break down, while applying the force of compression and friction between the particles while adding water to the aggregated clay sand put in the receiving hopper 14 The granular granite sand is refined and sent to the feed sump 2. In addition, as the treated water to be added to the rotary crusher 10, seawater pumped from the vicinity of the dredging work site may be used.
[0013]
Next, a method for treating dredged soil by the continuous processing system will be described.
As described above, the dredge pumped up directly by the dredging robot 1 is basically overwhelmingly water (seawater) and already slurried, so this is directly sent to the feed sump 2.
On the other hand, the existing landfill earth and sand are sent from the receiving hopper 14 to the rotary crusher 10, and are finely granulated while being added with water, and then sent to the feed sump 2. That is, the reclaimed earth and sand S introduced into the gap between the rotary drum 11 and the rotor 12 of the rotary crusher 10 is scraped upward by the outer blades 11W of the rotary drum 11 as shown in FIG. Since it is pulled downward by the inner blades 12W of the rotor 12, compressive stress and shear stress act on the landfill earth and sand S, and as shown in FIG. Each particle P of the reclaimed earth and sand S is separated and finely divided into almost independent fine particles p. Further, since the force in the rubbing direction acts on the particles p, the particles p are mutually polished, and the acute angle portion of each particle p is removed. Therefore, various sizes of gravel, sand and silt having a relatively smooth surface are sent from the rotary crusher 10 to the feed sump 2 together with the treated water.
The rotary crusher 10 and the feed sump 2 are respectively provided with pre-sorting means (not shown) for removing relatively large contaminants mixed in the input, The processing in the subsequent process is made smooth.
[0014]
In the present embodiment, for example, the dredged robot 1 sends the dredged material from the gulf or the outflow river with about 10% sediment and about 90% moisture to the feed sump 2 at about 1000 m ³ / H. Is about 60% and the water content is about 40%. It is sent to the feed sump 2 after being put into the rotary crusher 10 and refined. Saddle with about 20% earth and sand and about 80% moisture is stored. This soot is conveyed to a plurality of hydrocyclones 3 by a pump 9.
In the hydrocyclone 3, fine particles of less than about 100 μm in the porcelain are suspended in the treated water, and particles such as gravel and sand of about 100 μm or more are precipitated at the bottom as solids. The treated water containing fine particles of less than about 100 μm above the liquid cyclone 3 is returned to the feed sump 2 and sent to the thickener tank 6 as the supernatant of the feed sump 2. At this time, most of the salinity in the sediment is dissolved in the treated water and removed from the solids such as gravel and sand.
[0015]
However, since there is a possibility that some salt and microorganisms such as plankton are attached to the gravel and sand, the solid matter precipitated at the bottom of the hydrocyclone 3 is once accumulated in the spigot tank 4 and then aqua. It is sent to the screen 5, washed with washing water (shower or passing flooded water) and carried out. Salinity is a non-adsorbing substance and is not strongly adsorbed to the earth and sand, so it can be easily removed by the above washing. In the aqua screen 5, simultaneously with the washing, fine particles of less than about 100 μm mixed in the solid matter are separated and sent to the thickener tank 6 to take out particles such as gravel and sand of about 100 μm or more.
Particles having a large particle size such as gravel and sand separated by the aqua screen 5 are originally of good quality if the salt content is removed, so that they can be used as fine aggregate for concrete. It can also be used as a backfill material.
[0016]
The thickener tank 6 collects the supernatant of the feed sump 2 containing treated water at the top of the hydrocyclone 3 and the silt containing fine particles of less than about 100 μm separated by the aqua screen 5. A liquid containing solids such as fine particles of less than 100 μm is slowly rotated in a tank, and solid-liquid separation is performed to agglomerate and precipitate the fine particles.
The supernatant liquid of the thickener tank 6 is discharged into the ocean, and the precipitate is once homogenized in the slurry tank 7 and then dehydrated by a filter press 8 to produce a cake. This dehydrated cake has a reduced salt content and can be reused.
[0017]
As described above, in the present embodiment, the dredged material from the gulf or the outflow river dredged by the dredging robot 1 and the reclaimed sand by the rotary crusher 10 by the dredged soil continuous processing system. Are simultaneously added to the hydrocyclone 3, and the solid matter precipitated at the bottom of the hydrocyclone 3 is washed on the aqua screen 5 to remove earth and sand while removing salt and about 100 μm above the hydrocyclone 3. The treated water containing less than fine particles was separated into solid and liquid by the thickener tank 6 and the dehydrated cake was made from the sediment in the thickener tank 6, so that dredged sand dredged from the bay and rivers, Can be processed at the same time, and the classified soil and the prepared dewatered cake can be reused. The dredging sediment fill up to can be greatly reduced. Moreover, since it is a simple system centering on the hydrocyclone 3 without using a vibrating screen, the classification of dredged sand can be performed continuously and at high speed, and the classification efficiency of dredged sand can be improved. . Furthermore, by using the liquid cyclone 3, salt and the like can be removed efficiently.
[0018]
In the above embodiment, after the water has been mixed with water was added water to a approximately 80% finely ground dredged material by rotating crusher 10, when introducing the mixture into the hydrocyclone 3 Even when dredged soil is only landfill, it can be treated in the same manner as in the above embodiment.
[0019]
In the above example, the liquid cyclone 3 used is one that separates particles such as gravel and sand having a size of about 100 μm or more from the charged material, but the particle size separated by the liquid cyclone 3 is not limited to this. It is determined as appropriate according to the type of the material to be input, the purpose and specification of the processing system. Furthermore, if the liquid cyclones 3 are provided in a plurality of stages and the soot is classified, it is possible to classify with high accuracy and fineness. Note that the number of hydrocyclone 3 is intended to be determined by the processing amount and the like of the continuous processing system, you need not name is always more.
[0020]
As described above, according to the invention described in claim 1, and sends the Gulf or out river directly from pumped dredged material to the feed sump, the dredged material which has been previously deposited in grain refining means Feeding the finely-divided product while adding water to the feed sump , putting the soot stored in the feed sump into a liquid cyclone and classifying it, washing the solid precipitated at the bottom of the liquid cyclone with water, The removed solid matter is taken out, the treated water containing the fine particles at the top of the liquid cyclone is returned to the feed sump, and the supernatant of the feed sump and the washing water that has washed the solid matter are sent to a thickener tank. since then solid-liquid separation so as to take out the fine fraction of the dredged material in which salt is removed, the classification of the dredged material can be performed at high speed with a simple configuration, improved classification efficiency It is possible to, can process the dredged material which has been previously deposited with the dredged material was dredged direct simultaneously and at high speed.
[Brief description of the drawings]
FIG. 1 is a processing flow showing a dredged material processing method according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining the operation of a rotary crusher.
FIG. 3 is a diagram showing the structure of a conventional rotary crusher.
[Explanation of symbols]
1 浚 渫 Robot, 2 Feed sump, 3 Liquid cyclone, 4 Spigot tank, 5 Aqua screen, 6 Thickener tank, 7 Slurry tank, 8 Filter press, 9 Pump 10 Rotating crusher, 11 Rotating crusher, 11W Outer blade, 11a Ring Gear, 12 rotor, 12W inner blade, 12a rotating shaft, 12b drive mechanism, 13 motor, 14 receiving hopper.

Claims (1)

And it sends the Gulf or out river directly from pumped dredged material to the feed sump sends also to was comminuted while hydrolyzing the dredged material which has been previously deposited in grain refining means to a feed sump, the feed The soot stored in the sump is put into a liquid cyclone and classified , and the solids precipitated at the bottom of the liquid cyclone are washed with water to take out the solids from which the salt has been removed, and the fine particles on the top of the liquid cyclone The treated water containing water is returned to the feed sump, and the supernatant of the feed sump and the washing water for washing the solid matter are sent to a thickener tank to separate the solids and liquids, and the fine fraction in the porridge from which salt has been removed. processing method of dredged material, characterized in that retrieving the.

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