JP2008086921A - Washing method of contaminated sand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a washing method of contaminated sand, for the purpose of washing sand contaminated with excreta of animals or fine particles of earth entrained by rainwater in a sandbox of a park or a kindergarten, and improving fluidity or recovering characteristics of sand for a bunker of a golf course or farming. <P>SOLUTION: In this washing method of contaminated sand, contaminated sand is mixed with dilution water and formed into high speed slurry, and the speed of the slurry is rapidly reduced to separate contaminant in the contaminated sand. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for separating contaminants from contaminated sand.

  Sand and beach sand in parks and kindergartens, racetracks, bunkers in golf courses, and other contaminants such as fine foreign particles, animal excrement, and dead leaves are contaminated over time. The In addition, in sandy fields such as watermelons and straws, the soil itself is refined due to the residue of crop roots, contamination due to the inflow of fine foreign particles together with rainwater from the surrounding soil, and the cultivator working to refine the sand itself. The water retention becomes too large, and the characteristics such as sand permeability and fluidity deteriorate. As a result, the sandbox becomes unusable, and it becomes necessary to replace the entire amount of sand, resulting in a decrease in crop yield and quality.

Conventionally, the following methods are known as methods for cleaning contaminated sand.
Patent Document 1 uses a rotating slanted cylindrical tank with a built-in heating device, sucks contaminated sand into the cylindrical tank, sterilizes by mixing a bactericidal agent and an antibacterial agent, and then heat-drys to discharge the sand. The method is described.

  Patent Document 2 describes a method in which a contaminated sand cleaning liquid is pressed into a cylindrical tube containing a screw body, and sand is washed by a scouring effect caused by friction between sands generated when flowing along the screw body. Yes.

  However, the above method uses chemicals such as ozone water for cleaning, so the toxicity of residual ozone is uneasy, and it is not suitable for children's sandboxes that directly touch the skin. It cannot be used for cleaning. In addition, there is a problem that a heating device or a complicated device is required.

JP 2003-290324 A JP 2006-110502 A

  The present invention has been made in order to solve the above-mentioned problems. In a sandbox such as a park or kindergarten, washing of sand contaminated with fine particles of soil accompanied by animal manure or rainwater, a golf course bunker, To provide a method for cleaning contaminated sand for the purpose of improving fluidity and restoring properties of sand in agricultural sand.

As a result of diligent research to solve the above problems, the present inventors have found a method for obtaining cleaning sand using only water as a cleaning medium in consideration of the influence on the human body and the environment, and to complete the present invention. It came.
That is, the present invention is a method for cleaning contaminated sand, characterized in that contaminated sand and dilution water are used as a high-speed slurry, and the high-speed slurry is rapidly decelerated to separate contaminants in the contaminated sand. .

Hereinafter, the present invention will be described in detail.
Contaminated sand is composed of sand, contaminants and contained water, and since the contained water has a small volume, it has almost no fluidity.
Therefore, in this invention, dilution water is added to this contaminated sand, and the slurry which the contaminated sand disperse | distributed to the mixed water which consists of the water contained in contaminated sand and dilution water is made.

The composition of the slurry preferably satisfies 1.5 ≦ (G + K) / S ≦ 10, where S is the volume of contaminated sand, G is the volume of water contained in the contaminated sand, and K is the volume of diluted water. .
Generally, G is smaller than S, and the contaminated sand is not fluid. Therefore, dilution water is added to give fluidity to the contaminated sand. However, in order to ensure fluidity, G + K is 1.5 times or more of S. Preferably, too much water requires excessive energy to drive the slurry, so G + K is preferably 10 times or less than S.

  In the present invention, the slurry is increased in speed, and the high-speed slurry is rapidly decelerated to separate contaminants from the contaminated sand.

  Examples of means for obtaining a high-speed slurry include a means for mixing high-pressure water and soil using a water ejector. Further, as a means for rapidly decelerating the high-speed slurry, for example, in the case of a water ejector, a collision plate is installed in front of the traveling direction of the water ejector to decelerate the slurry, and further, a deceleration having a collision plate Can be used. The speed reducer is preferably a vertical cylindrical tank speed reducer with a built-in collision disk having a cross-sectional area capable of colliding with all the fluid of the slurry slightly decelerated flowing in from the water ejector, but is not limited thereto. Moreover, there may be not only one collision disk but also a plurality of collision disks.

  The distance between the tank wall of the vertical cylindrical tank and the collision disk is required to allow the slowed slurry to flow smoothly. It is preferable that the passing speed of the slurry in the gap between the collision disk and the tank wall of the cylindrical tank is 0.01 m / second or more.

In the present invention, the speed of the high-speed slurry is preferably 1 to 150 m / second, more preferably 1 to 50 m / second, and further preferably 5 to 30 m / second. When the speed of the high-speed slurry is in the above range, the contaminants can be efficiently peeled by decelerating with the collision plate.
In the present invention, after the contaminant is peeled from the contaminated sand, the contaminant is separated from the sand. Although the method to isolate | separate is not specifically limited, For example, it is preferable to use a sedimentation tank.

  Since the method of the present invention uses only water as a cleaning medium, there is no fear of causing chemical damage in cleaning of a sandbox in a kindergarten or field sand that can be touched manually. Furthermore, since the fine particles and plant secretions, which are one of the pollutants, can be almost certainly removed, the sand-specific properties such as sand fluidity and air permeability can be recovered.

  In addition, since the equipment itself is operated only by the action of water fluid, there is no need for rotating equipment other than pumps, and it is easy to install the equipment individually, so it is also suitable for washing golf bunker on bad terrain. It is easy to use. Furthermore, it is characterized in that it is more compact than conventional methods for separating fine particles using wind power.

Hereinafter, embodiments of the present invention will be described by dividing them into preferable steps.
(1) A slurrying process in which dilution water is added to contaminated sand composed of sand, contaminants and contained water to form a slurry.

  Sand is coarse sand having a particle size in the range of 2 mm to 0.85 mm, medium sand in the range of 0.85 mm to 0.25 mm, fine sand in the range of 0.25 mm to 0.075 mm, 0.075 mm to 0.005 mm. Of silt and a clay of 0.005 mm or less. Contaminants exist in these sand particles, but generally they adhere between the sand particles, are simply mixed with the sand, or adhere to the sand surface. By vigorously mixing, contaminants can be efficiently peeled from the sand.

  Therefore, when making a slurry, by injecting 0.5 to 30 MPa of diluted water pressurized by a high pressure hydrating apparatus into the mixer to generate a negative pressure suction force, It is preferable to sufficiently mix the above.

(2) A step of increasing the speed of the slurry to obtain a high-speed slurry.
For example, a water ejector is preferably used as a means for obtaining a high-speed slurry.
(3) A step of rapidly decelerating the flow rate of the high-speed slurry with a decelerator.
By this step, contaminants in the contaminated sand can be efficiently separated from the sand.

(4) The process of isolate | separating the slurry from which the contaminant was peeled from sand.
As the separation means, for example, a sedimentation tank can be used. By supplying the slurry to the sedimentation tank, the washing sand settles and is discharged to the lower part of the sedimentation tank, and most of the mixed water in which contaminants such as fine particles and germs are dispersed rises in the sedimentation tank. And continuously discharged from the upper part of the sedimentation tank.

As a condition for the mixed water in which the contaminants are dispersed to rise in the sedimentation tank, the content of fine particles accompanying the washing sand can be controlled by controlling the rising speed.
(5) A step of removing contaminants from the mixed water in which the contaminants are dispersed.
The means for removing is not particularly limited, and known means can be employed. Water from which contaminants have been removed can be recycled and reused.

In carrying out the present invention, it may be convenient to increase the economic efficiency and use the entire set of devices used in each of the above steps or loading them on a cart and using them in a movable state.
Such an embodiment includes a set of equipment having a mixer, a high-speed slurrying device, a slurry receiving tank, a slurry transfer pump, a settling separation tank, a discharge device, and a drainage tank. A cleaning apparatus is a preferred example. Needless to say, a known accessory device used for carrying out the method of the present invention can be loaded on the carriage as needed, in addition to the above-described devices.

FIG. 1 is a schematic diagram showing an example of a specific process using the method of the present invention.
The contaminated sand 1 is composed of particles having a particle size of 2 mm or less and contained water, and a small amount of water 3 is added to the contaminated sand 1 to obtain a wet sand 2 that is moistened into a gentle paste. Next, suction water 6 having a water pressure of 0.5 to 30 Mpa flows from one end of the mixer 5 in the shape of a horizontal cylinder, and the negative pressure suction force generated in the mixer is utilized to pass through the suction pipe 4. Aspirate the wet sand 2.

  The wet sand 2 collides with the other end of the mixer while forming a mixture with the suction water 6 inside the mixer 5, and then passes through the speed reducer 7 incorporating the collision plate. The body's velocity energy is reduced, resulting in a decelerated slurry 8. In addition, the water which added water 3 and the suction water 6 is dilution water, and the water which added the content water of contaminated sand to this dilution water is called mixed water.

  The slurry 8 is a slurry in which contaminated sand is dispersed in particles constituting the sand in mixed water, and fine particles of contaminants and bacteria are also dispersed in the same manner. The slurry 8 is stored in the slurry receiving tank 9 and simultaneously transferred from the slurry receiving tank 9 by the slurry transfer pump 10 and flows into the inner cylinder 12 mounted on the settling separation tank 13 installed at the tip of the pipe 11.

  The inner cylinder 12 has a function of preventing the inflowing slurry from flowing smoothly and disturbing the flow inside the sedimentation separation tank 13. Therefore, the equivalent diameter of the cross section of the inner cylinder 12 is selected so that the inflow rate into the settling tank is about 0.01 to 1 m / sec. The inner cylinder 12 is desirably installed vertically, and the immersion length in the sedimentation tank 13 is desirably 1.5 times or more the equivalent diameter.

The shape of the sedimentation separation tank 13 is composed of a barrel portion having an arbitrary shape such as a cylinder or a rectangular tube and a bottom portion such as an inverted cone or an inverted pyramid connected to the barrel portion, and the inner cylinder 12 is a central portion of the barrel portion. The inlet of the inner cylinder 12 is provided above the liquid level of the sedimentation tank 13.
Most of the sand in the slurry that has passed through the inner cylinder 12 settles and accumulates at the bottom of the settling tank, and is discharged by the discharge device 14 to obtain the washed sand 15.

  On the other hand, contaminants are dispersed in most of the mixed water separated from the slurry, and the mixed water becomes an upward flow and flows out from the upper part of the settling separation tank 13 to become drainage 16. Since the upward flow needs to be accompanied by fine particles corresponding to the pollutant, it is necessary to adopt the cross-sectional area of the sedimentation separation tank 13 so that the speed of the upward flow becomes a speed based on the Stokes theory. .

Since the pollutant is dispersed in the drainage 16, it is stored in the drainage tank 17 and then transferred to the next treatment facility using the drainage pump 18.
Supply water 23 for suction water 6 and hydration 3 is stored in a new water tank 20 and supplied by a pressure water pump 21 and a hydration pump 22.

Using the method of the present invention, the contaminated sand whose sand was refined by using a cultivator was washed on the farmland, and the following results were obtained.
The composition of the processing amount of the contaminated sand 1 of 900 liter / hr was 500 liter / hr of sand particles having a particle size of 20 microns or more, 100 liter / hr of fine particles of 20 microns or less, and 300 liter / hr of water.

  This contaminated sand 1 was subjected to water 3 at 200 liters / hr to form wet sand 2. Next, while a suction pressure of 3 Mpa is injected from one end of a horizontal cylindrical mixer 5 having a diameter of 50 mm and a length of 1000 mm at 1300 liter / hr, a negative pressure is generated inside the mixer 5. The wet sand 2 was sucked through the suction pipe 4 connected to 5. The mixture of the wet sand 2 and the suction water collides with the other end face of the mixer 5, and then passes through a cylindrical speed reducer 7 with a diameter of 300 mm and a length of 300 mm containing a disk with a diameter of 200 mm. It becomes.

This slurry 8 was stored in a 1 m ³ slurry receiving tank 9, transferred using a slurry transfer pump 10, and supplied to an inner cylinder 12 built in a sedimentation separation tank 13 installed 50m away. . The inner cylinder 12 has a diameter of 100 mm and an immersion length of 250 mm.
The shape of the sedimentation separation tank 13 is a cylindrical conical tank composed of a cylindrical body having a diameter of 600 mm and a length of 300 mm and a bottom of an inverted cone having a diameter of 600 mm and a height of 400 mm.

Most of the sand in the slurry that passed through the inner cylinder 12 settled to the bottom of the settling separation tank and was discharged by a screw-type discharge device to obtain washed sand. The discharge device may be a rotary valve type.
The composition of the washed sand 15 was 490 liter / hr for sand having a particle size of 20 microns or more, 16 liter / hr for fine particles having a particle size of 20 microns or less, and 300 liter / hr for entrained water.

On the other hand, most of the mixed water became an upward flow and overflowed from the upper end of the settling tank 13 to become drainage 16. The composition of the waste water 16 was 10 liter / hr for sand having a particle size of 20 microns or more, 84 liter / hr for fine particles having a particle size of 20 microns or less, and 1500 liter / hr for entrained water.
As a result, 84% of fine particles having a particle diameter of 20 microns or less could be removed.

It is the schematic which shows an example of the concrete process using the method of this invention.

Explanation of symbols

1 Contaminated sand 2 Wet sand 3 Water 4 Suction tube 5 Mixer 6 Suction water 7 Speed reducer

8 Slurry decelerated 9 Slurry receiving tank 10 Slurry transfer pump 11 Pipe 12 Inner cylinder 13 Sedimentation separation tank 14 Discharge device 15 Washing sand

16 Drainage 17 Drainage tank 18 Drainage pump 20 New water tank 21 Pressure water pump 22 Water pump 23 Supply water

Claims (5)

  A method for cleaning contaminated sand, characterized in that contaminated sand and dilution water are used as a high-speed slurry, and the high-speed slurry is rapidly decelerated to separate contaminants in the contaminated sand.   When the volume of contaminated sand is S, the volume of contained water in the contaminated sand is G, and the volume of diluted water is K, the composition of the slurry satisfies 1.5 ≦ (G + K) / S ≦ 10. The method for cleaning contaminated sand according to claim 1.   3. The method for cleaning contaminated sand according to claim 1, wherein the high-speed slurry has a speed of 1 to 150 m / sec.   The method for cleaning contaminated sand according to any one of claims 1 to 3, wherein a speed reducer having a collision plate is used as the speed reducing means.   A contaminated sand cleaning device in which a complete set of equipment including a mixer, a high-speed slurrying device, a slurry receiving tank, a slurry transfer pump, a sedimentation separation tank, a discharge device, and a drainage tank are loaded on a carriage.

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