JP2022134892A - Collection method of undersea resources - Google Patents

Abstract

To provide a collection method of undersea resources capable of efficiently collecting undersea resources contained in the mud of the underwater ground.SOLUTION: An insertion tube 3 connected to a bottom of a suction-collection pipe 2 is inserted into an underwater ground B. Then, while a liquid L is supplied into the insertion tube 3, stirring blades 6 attached to a bottom of a rotary shaft 4 inside the insertion tube 3 is rotated. Mud S inside the insertion tube 3 is excavated and dissolved by the stirring blades 6, and the mud S dissolved into a slurry is lifted to above the water through the suction-collection pipe 2 by lifting means. At this time, a deepest penetration position D1 of the stirring blades 6 is held above a lower end of the insertion tube 3 by a predetermined distance T, in a state that a lower-end opening 3c of the insertion tube 3 is blocked with the mud S of the underwater ground B, so as to prevent the slurried mud S from flowing out of the insertion tube 3 through the lower-end opening 3c.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method for extracting bottom-of-water resources, and more particularly to a method for extracting bottom-of-water resources capable of efficiently extracting bottom-of-water resources contained in mud of bottom-of-water ground.

In the development of marine resources, we use pump lifts, air lifts, and other means of lifting and collecting mud from the bottom of the sea, which contains bottom-of-water resources such as rare earths that exist in the deep sea, along with liquids such as water, to lift-and-recover ships on the water. are being harvested. The larger the mud mass, the more liquid volume is required to lift and collect it. As the amount of liquid that is lifted up and collected together with the mud increases, the number of man-hours required for the lifting and collection work and the work to separate the mud and the liquid increases, and the cost required for extracting bottom water resources also increases. Therefore, in order to efficiently extract the water bottom resources contained in the mud of the water bottom ground, it is important to finely thaw the mud of the water bottom ground and lift it up with a smaller amount of liquid.

Conventionally, various systems have been proposed for excavating and lifting up mud from the bottom of water (see Patent Document 1). In the marine resource lifting device of Patent Literature 1, a recovery hopper provided at the lower portion of the lifting pipe portion faces the ground surface of the underwater ground. Next, the rotated bit penetrates the bottom of the sea, and an emulsion (oil mixed with a surfactant) with a specific gravity lighter than that of seawater is sprayed from the nozzle at the bottom of the bit to clear the mud of the bottom of the sea. excavate. Mud and emulsion that have risen from the bottom of the water to the upper part of the collection hopper are lifted onto the water via the lifting pipe. In this method, most of the mud in the waterbed ground excavated by the bit spreads in the waterbed ground, so the mud cannot be finely thawed. Therefore, in this marine resource lifting apparatus, an emulsion having a specific gravity lighter than that of seawater is injected into the seabed ground in order to raise the mud. However, since it is necessary to inject a large amount of emulsion into the waterbed ground and lift it up, the number of man-hours for separating the lifted mud and the emulsion increases, and the cost required for collecting waterbed resources increases. There is also a concern that the emulsion that flows out into the water will harm the aquatic environment.

Japanese Patent Application Laid-Open No. 2019-11568

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for extracting bottom water resources that enables efficient extraction of bottom water resources contained in the mud of the bottom ground.

In order to achieve the above object, the method of extracting a bottom-of-water resource of the present invention is a method of extracting a bottom-of-water resource in which mud in the bottom-of-water ground containing the bottom-of-water resource is excavated and lifted onto the water, wherein A liquid is supplied to the inside of the insertion pipe in a state where at least the lower part of the insertion pipe connected to the lower part of the lifting and receiving pipe is inserted into the seabed ground, and the lifting A rotating shaft extending in the tube axial direction inside the storage tube and the insertion tube, and a stirring blade attached to the lower part of the rotating shaft are rotated inside the insertion tube to rotate the stirring blade The mud inside the insertion pipe is excavated and demulsified by the dissolution, and the mud made into a slurry by the dissolution is lifted above the water through the lifting pipe by the lifting means, and the deepest penetration position of the stirring blade is a predetermined distance above the lower end of the insertion pipe, and the lower end opening of the insertion pipe is maintained in a state where it is blocked by the mud of the waterbed ground, and the slurry-like mud flows through the lower end opening of the insertion pipe. It is characterized by preventing it from flowing out to the outside.

According to the present invention, the liquid is supplied to the inside of the insertion pipe inserted into the waterbed ground, and the stirring blade is rotated to excavate and demuld the mud inside the insertion pipe. Moreover, the deepest penetration position of the stirring blade is set above the lower end of the insertion pipe by a predetermined distance, and the lower end opening of the insertion pipe is maintained in a state where it is blocked by the mud of the waterbed ground, and the slurry-like mud is inserted. It is prevented from flowing out to the outside of the insertion tube through the lower end opening of the tube. As a result, the mud inside the insertion pipe can be effectively pulverized into a slurry with a relatively small amount of liquid, and the mud can be efficiently raised to the upper portion of the insertion pipe while eliminating wasteful outflow. Therefore, the water bottom resources contained in the mud of the water bottom ground can be efficiently collected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram illustrating an outline of an embodiment of a bottom water resource extraction method of the present invention; FIG. 2 is an explanatory view illustrating the inside of the insertion tube of FIG. 1 in plan view; FIG. 3 is an explanatory diagram illustrating the inside of the insertion tube in the A arrow view of FIG. 2 ; FIG. 3 is an explanatory diagram illustrating the inside of the insertion tube in the B arrow view of FIG. 2 ; 1. It is explanatory drawing which illustrates the state which inserted the insertion pipe of FIG. 1 in the water bottom ground. FIG. 6 is an explanatory diagram illustrating a state in which the stirring blades have penetrated from the state of FIG. 5 to the deepest penetration position of the submerged ground; 7 is an explanatory diagram illustrating a state in which the stirring blade is reciprocated in the tube axis direction inside the insertion tube from the state in FIG. 6. FIG. It is a graph which illustrates time transition of the penetration depth of a stirring blade.

Hereinafter, the method for extracting bottom water resources of the present invention will be described based on the embodiment shown in the drawings. In the present invention, a bottom-of-water resource extraction system 1 (hereinafter referred to as a bottom-of-water resource extraction system 1) illustrated in FIG. and hoist it on the water.

The sampling system 1 includes a lift-and-storage pipe 2 extending from the surface of the water toward the seabed ground B, an insertion pipe 3 connected to the lower part of the lift-and-storage pipe 2, and the inside of the lift-and-storage pipe 2 and the insertion pipe 3. and an axially extending rotating shaft 4 . The collection system 1 further includes a stirring blade 6 attached to the lower portion of the rotating shaft 4 and a liquid supply mechanism 8 for supplying the liquid L into the insertion tube 3 . The collection system 1 of this embodiment further comprises an intensity sensor 9 and a pressure sensor 10 installed in the insertion tube 3 . This embodiment exemplifies the case where the lifting pipe 2 is connected to the lifting and receiving ship 20 on the water, but it is not limited to the lifting and receiving ship 20. For example, the lifting and receiving pipe 2 is provided on the water. It can also be configured to be connected to a facility or the like.

The lift-and-storage pipe 2 and the insertion pipe 3 are in communication. The inner diameter of the insertion tube 3 is set larger than the inner diameter of the lift-and-storage tube 2 . The inner peripheral surface of the connecting portion between the lifting tube 2 and the insertion tube 3 has a smoothly continuous curved shape. The inner diameter of the lift-and-storage tube 2 is set, for example, within a range of 0.2 m or more and 1.0 m or less, and the inner diameter of the insertion tube 3 is set, for example, within a range of 0.5 m or more and 5 m or less. A lifting means is connected to the lifting pipe 2 for lifting the mud S raised to the upper part of the insertion pipe 3 through the lifting pipe 2 to the surface of the water. The pumping means is composed of, for example, an air lift pump, a slurry pump, or the like.

When collecting the mud S of the waterbed ground B, the insertion pipe 3 is in a state in which at least the lower part thereof is inserted into the waterbed ground B, and the upper part of the insertion pipe 3 protrudes upward from the surface of the waterbed ground B. . For example, 50% or more of the total length of the insertion pipe 3 is inserted into the seabed ground B. The length of the insertion tube 3 in the tube axis direction is appropriately set according to the depth of the stratum in which the submerged resources are distributed. In this embodiment, an annular stopper 3a is provided on the outer peripheral surface of the insertion tube 3 in plan view. With this stopper 3a as a boundary, the region of the insertion pipe 3 below the stopper 3a is inserted into the waterbed ground B, and the region of the insertion pipe 3 above the stopper 3a is below the surface of the waterbed ground B. will also protrude upwards.

The rotating shaft 4 is suspended from the hoisting/receiving vessel 20 through the hoisting/storage pipe 2 and the insertion pipe 3, and is rotated by a drive mechanism. As illustrated in FIGS. 2 to 4, in this embodiment, a stirring blade 6 for excavating and dissolving the mud S is attached to the head 5 which is detachably connected to the lower portion of the rotating shaft 4. . An excavating edge 7 for excavating the mud S of the water bottom ground B is provided at the lower end of the head 5 . A group of agitating blades 6 composed of a plurality of agitating blades 6 is provided on the outer peripheral surface of the head 5 located above the excavating blade 7 . Each stirring blade 6 extends toward the inner peripheral surface of the insertion tube 3 . A plurality of stirring blades 6 constituting the same stirring blade group are arranged at intervals in the circumferential direction of the rotating shaft 4 .

Each stirring blade 6 in this embodiment is formed in a flat plate shape and has a tapered shape that tapers from the root portion connected to the rotating shaft 4 (head 5) toward the tip. The front end portion of the stirring blade 6 in the rotation direction is sharply pointed. For example, the front end portion of the stirring blade 6 can be formed in a sawtooth shape with continuous peaks and valleys. The stirring impeller 6 is not limited to a flat plate shape, and can be curved like a screw blade, for example.

In this embodiment, a stirring blade group composed of two stirring blades 6 arranged at opposing positions is provided in three stages in the axial direction of the rotating shaft 4 . Each of the stirring blades 6 constituting the lowest stage stirring blade group is inclined downward in the direction of rotation. Each of the stirring blades 6 constituting the middle stirring blade group and the uppermost stirring blade group is inclined upward in the direction of rotation. As illustrated in FIG. 4, the angle θ (depression angle) between the axial direction of the rotating shaft 4 and the extending direction of the stirring blades 6 is, for example, 10 degrees or more and 80 degrees or less, preferably 20 degrees or more and 70 degrees or less. It is preferably set within the range of 25 degrees or more and 40 degrees or less.

The stirring blades 6 adjacent to each other in the axial direction of the rotating shaft 4 are arranged at positions shifted in the circumferential direction of the rotating shaft 4 in plan view. A gap (clearance) of about 50 mm to 500 mm is provided between the inner peripheral surface of the insertion tube 3 and the tip of the stirring blade 6 . The rotation speed of the stirring blade 6 (rotating shaft 4) is, for example, 10 rpm to 200 rpm.

The number of stages of the stirring blade group provided in the axial direction of the rotating shaft 4 and the number of the stirring blades 6 constituting each stage of the stirring blade group are not limited to this embodiment, and may be configured differently. For example, it is also possible to adopt a structure in which a stirring blade group composed of three stirring blades 6 is provided in two stages in the axial direction of the rotating shaft 4 . The stirring blades 6 constituting each stirring blade group are preferably arranged so as to be point-symmetrical about the axis of the rotating shaft 4 in plan view. The direction of inclination of the stirring blades 6 constituting the stirring blade groups of each stage is not limited to this embodiment. A downward sloping configuration is also possible.

The liquid supply mechanism 8 supplies water (seawater or freshwater) as the liquid L, for example. It is convenient to use on-site water (sea water or fresh water) that is available on-site. In addition, as the liquid L, for example, a liquid obtained by adding an additive to water, or a liquid other than water may be supplied. The liquid supply mechanism 8 of this embodiment has a jet nozzle 8 a provided at the tip of the stirring blade 6 . A liquid supply device installed on the surface of the water (ship 20) supplies liquid L to each injection nozzle 8a through a main pipe extending inside the rotating shaft 4 and a plurality of pipes 8b branched from the lower part of the main pipe. is supplied.

The injection nozzle 8a and the pipe 8b are attached to the rear side of the stirring blade 6 with respect to the rotating direction of the stirring blade 6. As shown in FIG. For example, the jet nozzle 8a and the pipe 8b may be installed in the stirring blade 6 so that the liquid L is jetted from the tip of the stirring blade 6 . In this embodiment, all the stirring blades 6 are provided with the injection nozzles 8a, but some of the stirring blades 6 can be selectively provided with the injection nozzles 8a. That is, for example, the injection nozzle 8a can be provided only for each stirring blade 6 that constitutes the lowest stage stirring blade group.

Even when the injection nozzles 8a are selectively provided in some of the stirring blades 6, the injection nozzles 8a provided in each stage should be arranged so as to be point-symmetrical about the axis of the rotating shaft 4 in plan view. is preferred. It should be noted that the liquid supply mechanism 8 may have any structure as long as it can supply the liquid L into the insertion tube 3, and is not limited to the structure of this embodiment.

The strength sensor 9 measures the strength of the unexcavated water bottom ground B. As shown in FIG. Examples of the index indicating the strength of the waterbed ground B include the uniaxial compressive strength of the mud S of the waterbed ground B in the direction of the tube axis, the N value, and the cone index. As the strength sensor 9, for example, a soil hardness meter, a soil layer strength test rod, or the like is used. The strength sensor 9 is installed at a position where the insertion tube 3 is inserted into the waterbed ground B. For example, the intensity sensor 9 is preferably installed near the lower end opening 3c of the insertion tube 3 (at a position where the distance from the lower end opening 3c in the tube axial direction is within 30 cm). In this embodiment, the strength sensor 9 is installed on the inner peripheral surface of the insertion tube 3 at a position that does not come into contact with the stirring blades 6, but it can also be installed on the outer peripheral surface or the lower end surface of the insertion tube 3, for example.

The pressure sensor 10 measures the pressure inside the insertion pipe 3 inserted into the seabed ground B. The pressure sensor 10 is installed, for example, in a range to be an excavation target region R1 in which the mud S is excavated and thawed by the stirring blades 6 . For example, the pressure sensor 10 may be arranged at a position where the distance upward from the lower end 3b of the insertion tube 3 is 100 cm or more and 500 cm or less. In this embodiment, the pressure sensor 10 is installed on the inner peripheral surface of the insertion tube 3 at a position where it does not come into contact with the stirring blades 6 . The measurement data of the strength sensor 9 and the pressure sensor 10 are sequentially transmitted to the management section on the water (the recovery vessel 20) so that the manager can grasp them. The intensity sensor 9 and the pressure sensor 10 can each be optionally provided.

Next, an example of a working procedure of a method for collecting bottom water resources using this collection system 1 will be described below.

An insertion tube 3 is connected to the lower part of the lifting and receiving tube 2, and a head 5 is detachably fixed inside the upper part of the insertion tube 3. - 特許庁As illustrated in FIG. 5, a lifting pipe 2 is extended from the surface of the water (a lifting ship 20) toward the waterbed ground B, and at least the lower part of the insertion pipe 3 is inserted into the unexcavated waterbed ground B. The upper part of the insertion tube 3 containing the head 5 is not inserted into the water bottom ground B, and the head 5 is arranged above the surface of the water bottom ground B. - 特許庁

At this stage, the inside of the lower part of the insertion pipe 3 inserted into the waterbed ground B is filled with the mud S of the waterbed ground B that has not yet been excavated. The inside of the upper part of the insertion pipe 3, which is not inserted into the seabed ground B, is filled with the water W of the water area. While the insertion tube 3 is being inserted into the waterbed ground B, the strength of the waterbed ground B is successively measured by the strength sensor 9 .

In this embodiment, when the insertion pipe 3 is inserted into the seabed ground B to a position where the stopper 3a provided on the outside of the insertion pipe 3 contacts the surface of the seabed ground B, the depth of the stratum in which the waterbed resources are distributed is reached. The lower part of the insertion tube 3 is inserted. The upper part of the insertion tube 3 in which the head 5 is housed protrudes above the surface of the submerged ground B.

Next, the rotating shaft 4 is lowered from the surface of the water (the hoisting and recovering vessel 20) toward the seabed B while being inserted into the inside of the hoisting pipe 2 and the insertion pipe 3, and the head 5 is attached to the lower end of the rotating shaft 4. (Stirring blade 6) is connected. With the head 5 connected to the lower end of the rotating shaft 4 , the head 5 is removed from the insertion tube 3 when the rotating shaft 4 is further moved downward toward the waterbed ground B. As a result, the head 5 (stirring blade 6) integrated with the rotating shaft 4 becomes movable in the direction of the tube axis.

Next, as illustrated in FIG. 6, the liquid supply mechanism 8 supplies the liquid L to the inside of the insertion tube 3, and the rotating shaft 4 and the stirring blade 6 attached to the lower part (head 5) of the rotating shaft 4 is rotated inside the insertion tube 3. Then, the rotating impeller 6 penetrates the mud S of the water bottom ground B from the surface of the water bottom ground B to excavate the mud S inside the insertion pipe 3 and dissolve it into slurry. In this embodiment, by injecting the liquid L from the injection nozzle 8a toward the inner peripheral surface of the insertion tube 3 at high pressure, while supplying the liquid L to the inside of the insertion tube 3, the tip of the stirring blade 6 and the insertion tube The mud S between the inner peripheral surface of 3 is excavated and demulsified. The pressure inside the insertion tube 3 (hereinafter referred to as the internal pressure of the insertion tube 3) is sequentially measured by the pressure sensor 10. FIG.

When the agitating blade 6 penetrates into the submerged ground B, the deepest penetration position D1 of the agitating blade 6 (the lowest agitating blade 6) is set above the lower end 3b of the insertion pipe 3 by a predetermined distance T. Then, the lower end opening 3c of the insertion pipe 3 is kept closed by the mud S of the waterbed ground B, and the mud S disintegrated into a slurry state by the stirring blade 6 flows into the insertion pipe 3 through the lower end opening 3c of the insertion pipe 3. Prevent it from leaking outside.

That is, the mud S in the excavation target region R1 from the surface of the submerged ground B inside the insertion pipe 3 to the deepest penetration position D1 is excavated and dissipated by the stirring blade 6, and the deepest penetration position D1 and the lower end 3b of the insertion pipe 3 are separated. A non-excavation region R2 having a thickness of a predetermined distance T in the pipe axial direction is left between the position depth D2. Then, the lower end opening 3c of the insertion pipe 3 is plugged with the mud S in the non-excavation region R2 that is relatively hard with respect to the thawed earth and sand S. In the drawing, the unexcavated mud S is indicated by hatching.

The above-mentioned predetermined distance T is such that even when the internal pressure of the insertion pipe 3 becomes maximum when the mud S inside the insertion pipe 3 is excavated and demulsified by the stirring blade 6, the lower end opening 3c of the insertion pipe 3 is The distance is set to prevent the mud S in the blocking non-excavation region R2 from collapsing due to the internal pressure of the insertion pipe 3. The resistance of the mud S in the non-excavation area R2 against the internal pressure of the insertion pipe 3 increases as the strength of the waterbed ground B (eg, uniaxial compressive strength, N value, cone index, etc.) and the predetermined distance T increase.

Therefore, the proper predetermined distance T that can prevent the mud S blocking the lower end opening 3c of the insertion pipe 3 from collapsing due to the internal pressure of the insertion pipe 3 is determined by the strength of the seabed ground B and the internal pressure of the insertion pipe 3. can be set based on By setting the predetermined distance T, it is possible to set the deepest penetration position D1 where the stirring blade 6 penetrates from the relationship with the depth D2 where the lower end 3b of the insertion tube 3 is located.

The strength of the waterbed ground B can be obtained by the strength sensor 9 when the insertion pipe 3 is inserted into the waterbed ground B as in this embodiment, or it can be obtained in advance before the insertion pipe 3 is inserted into the waterbed ground B. You can also keep it. Alternatively, the strength of the waterbed ground B can be obtained both before and during the insertion of the insertion pipe 3 into the waterbed ground B.

When obtaining the strength of the waterbed ground B in advance, for example, a known strength test (for example, a uniaxial compression test or a standard intrusion test, etc.). If the strength sensor 9 is provided as in this embodiment, the strength of the water bottom ground B can be measured by the strength sensor 9 when the insertion pipe 3 is inserted into the water bottom ground B.

When the strength of the waterbed ground B is obtained both before and when the insertion pipe 3 is inserted into the waterbed ground B, the measured value of the strength of the waterbed ground B that is relatively lower is adopted. and set the predetermined distance T. By doing so, the mud blocking the lower end opening 3c of the insertion pipe 3 is more likely than the case where the predetermined distance T is set based on the measured value either before or when the insertion pipe 3 is inserted into the waterbed ground B. S can be more reliably prevented from collapsing due to the internal pressure of the insertion tube 3 .

The internal pressure of the insertion pipe 3 inserted into the waterbed ground B can be obtained by the pressure sensor 10 after the insertion pipe 3 is inserted into the waterbed ground B as in this embodiment, or the insertion pipe 3 is inserted into the waterbed ground B. You can also get it in advance. Alternatively, the internal pressure of the insertion tube 3 can be obtained both before and after the insertion tube 3 is inserted into the seabed ground B.

The internal pressure of the insertion pipe 3 inserted into the waterbed ground B is based on the conditions such as the dimensions of the insertion pipe 3, the amount of liquid supplied to the inside of the insertion pipe 3 per unit time, and the amount of lifting per unit time by the lifting means. , can be calculated in advance. The internal pressure of the insertion tube 3 can also be obtained in advance by performing a preliminary test using the sampling system 1 or a simulation using a computer. For example, in the preliminary test, while supplying the liquid L to the inside of the insertion pipe 3 inserted in the waterbed ground B, the mud S inside the insertion pipe 3 is excavated and demulsified by the stirring blade 6. The pressure sensor 10 measures the internal pressure of the insertion tube 3 at R1.

By providing the pressure sensor 10 as in this embodiment, in the process of penetrating the stirring blades 6 into the waterbed ground B after inserting the insertion pipe 3 into the waterbed ground B, The pressure sensor 10 can measure the internal pressure of the insertion tube 3 . Then, the predetermined distance T can be set using the measured value of the internal pressure of the insertion tube 3 acquired by the pressure sensor 10 in the process of penetrating the stirring blade 6 .

When excavating and dissolving the mud S, the rotation speed and movement speed of the stirring blade 6, the amount of liquid supplied to the inside of the insertion tube 3 per unit time, the amount of liquid lifted per unit time by the lifting means, etc. When the conditions are changed, the internal pressure of the insertion tube 3 fluctuates accordingly. Therefore, it is preferable to set the predetermined distance T based on the maximum value of the internal pressure of the insertion pipe 3 during excavation and thawing.

When acquiring the internal pressure of the insertion tube 3 both before and after inserting the insertion tube 3 into the seabed ground B, the measured value with the relatively higher maximum internal pressure of the insertion tube 3 is adopted. and set the predetermined distance T. By doing so, the mud blocking the lower end opening 3c of the insertion pipe 3 is more likely than the case where the predetermined distance T is set based on either the measured value before or after inserting the insertion pipe 3 into the waterbed ground B. S can be more reliably prevented from collapsing due to the internal pressure of the insertion tube 3 .

After penetrating the stirring blade 6 to the deepest penetration position D1, as illustrated in FIG. In the shallow range), the mud S in the excavation target region R1 is repeatedly dismantled by reciprocating in the pipe axis direction. The number of times the stirring blades 6 are reciprocated can be appropriately determined according to the strength of the submerged ground B, the number of the stirring blades 6, the rotational speed of the stirring blades 6, etc. For example, the reciprocating motion is performed a plurality of times, about 2 to 15 times. Good. Although the work of reciprocating the stirring blades 6 can be omitted as appropriate, if this work is performed, the mud S in the excavation target region R1 can be made finer with greater certainty.

The mud S in the excavation target region R1 finely grained inside the insertion pipe 3 is mixed with the liquid inside the insertion pipe 3 (including the water W in the water area and the liquid L supplied by the liquid supply mechanism 8). It will be in a floating state, and the inside of the insertion pipe 3 above the deepest penetration position D1 will be in a state filled with slurry-like mud S. Then, the mud S in the excavation target region R1 made into a slurry by desludging is lifted to the upper part of the insertion pipe 3, and the raised slurry mud S is lifted up on the water (lifting ship) through the lifting pipe 2 by lifting means. 20).

By supplying new liquid L from the liquid supply mechanism 8 (injection nozzle 8a) to the inside of the insertion pipe 3, the water W inside the insertion pipe 3 and the mud S in the excavation target region R1 are newly supplied. Substitution with the liquid L is facilitated. Furthermore, the rotation of the stirring blade 6 generates a stirring flow inside the insertion tube 3, so that the mud S finely granulated inside the insertion tube 3 easily rises to the upper part of the insertion tube 3, and is efficiently lifted up on the water.

Thus, in the present invention, the liquid L is supplied to the inside of the insertion tube 3 inserted into the submerged ground B, and the stirring blades 6 are rotated to excavate and disintegrate the mud S inside the insertion tube 3 . Moreover, the deepest penetration position D1 of the stirring blade 6 is set above the lower end 3b of the insertion tube 3 by a predetermined distance T, and the lower end opening 3c of the insertion tube 3 is kept closed with the mud S of the waterbed ground B, It prevents the slurry-like mud S from flowing out of the insertion pipe 3 through the lower end opening 3 c of the insertion pipe 3 . As a result, the mud S inside the insertion pipe 3 is effectively finely granulated into a slurry with a relatively small amount of liquid, while avoiding waste due to the outflow of the slurry-like mud S. can be effectively raised to Therefore, the water bottom resources contained in the mud S of the water bottom ground B can be efficiently collected. By preventing the disintegrated mud S from flowing out, it is possible to prevent the state of the mud S around the outer periphery of the insertion tube 3 from being disturbed. Even when a liquid other than water is supplied as the liquid L, it is possible to prevent the liquid L from flowing out into the water outside the insertion tube 3, so the risk of harming the underwater environment is extremely low.

At first glance, it can be thought that more water bottom resources can be collected by setting the predetermined distance T to substantially zero and penetrating the stirring blades 6 as deeply as possible to disintegrate the mud S. However, the strength of the mud S of the seabed ground B, which contains seabed resources such as rare earths, is relatively low, and the depth of the water is deep, so there are many uncertain factors. Therefore, when the stirring blades 6 are penetrated to the lower end 3b of the insertion tube 3, the mud S demulsified inside the insertion tube 3 and the supplied liquid L are released to the outside of the insertion tube 3 through the lower end opening 3c of the insertion tube 3. very high risk of spillage. When such an outflow occurs, the slurry-like mud S dissipates and the internal pressure of the insertion tube 3 drops rapidly. Therefore, the efficiency of lifting and collecting the mud S is lowered. The present invention is a simple method in which a non-excavation area R2 having a thickness of a predetermined distance T is intentionally left in the lower part of the insertion pipe 3, but the efficiency of lifting and collecting the mud S can be effectively and stably improved. It has become. Therefore, it is a very useful method for those skilled in the art.

In addition, the inner diameter of the lifting pipe 2 used in the deep sea is small, and the gap between the inner peripheral surface of the lifting pipe 2 and the rotating shaft 4 is relatively narrow, but the mud S inside the insertion pipe 3 has a small amount of soil mass. Since it flows into the lifting/storage pipe 2 in a fine-grained state, the mud S is less likely to clog the suction/storage pipe 2.例文帳に追加Therefore, troubles are unlikely to occur in the lifting pipe 2, and the mud S of the water bottom ground B can be lifted up and collected very smoothly.

In order to efficiently disaggregate the mud S and generate an effective stirring flow, the rotational speed of the stirring blade 6 should be 20 rpm or more, more preferably 40 rpm or more. In particular, in order to generate a stirring flow that raises the mud S, the rotational speed of the stirring blades 6 must be increased accordingly. On the other hand, since there is a limit to how fast the stirring blades 6 can be rotated, the upper limit of the rotation speed is, for example, about 80 rpm or 60 rpm.

The moving speed of the stirring blades 6 in the pipe axis direction can be appropriately set according to the strength of the mud S of the water bottom ground B and the like. Specifically, for example, the moving speed of the stirring impeller 6 in the tube axis direction is preferably set within the range of 1 mm/sec to 100 mm/sec, more preferably 1 mm/sec to 10 mm/sec. The horizontal axis of the graph in FIG. 8 indicates the elapsed time after the impeller 6 penetrates into the submerged ground B, and the vertical axis indicates the penetration depth of the impeller 6 with the surface of the submerged ground B as the reference (0 m). ing. As shown in the graph of FIG. 8, the moving speed of the stirring blade 6 in the pipe axial direction when penetrating the stirring blade 6 from the surface of the submerged ground B to the deepest penetration position D1 after that inside the insertion pipe 3 When the stirring blades 6 are reciprocally moved in the pipe axis direction, it is preferable to set the moving speed of the stirring blades 6 in the pipe axis direction high.

When the impeller 6 penetrates into the unexcavated waterbed ground B, the mud S of the waterbed ground B has not been thawed, and the load applied to the agitation impeller 6 is relatively large. In this case, by penetrating the stirring blades 6 while setting the moving speed of the stirring blades 6 in the tube axis direction relatively slow, it is possible to avoid applying an excessive load to the stirring blades 6 . The mud S that has been excavated once is in a state of being demulsified to some extent, and the load applied to the stirring blades 6 is relatively small. Therefore, after the stirring blades 6 have penetrated to the deepest penetration position D1, the moving speed of the stirring blades 6 in the pipe axis direction is set relatively fast and the mud S inside the insertion pipe 3 is removed. It can be thawed efficiently.

When the liquid L is injected from the injection nozzle 8a provided at the tip of the stirring blade 6 toward the inner peripheral surface of the insertion tube 3, the tip of the stirring blade 6 and the inner peripheral surface of the insertion tube 3 that the stirring blade 6 does not reach. The mud S between them can be excavated and demulsified. Therefore, the mud S inside the insertion pipe 3 can be comprehensively lifted up. Furthermore, by arranging the injection nozzle 8a at the tip of the stirring blade 6 near the inner peripheral surface of the insertion tube 3, it is possible to cut the mud S between the tip of the stirring blade 6 and the inner peripheral surface of the insertion tube 3. The injection pressure of the liquid L required for is relatively low.

When the respective stirring blades 6 constituting the lowest stage stirring blade group are configured to be inclined downward in the direction of rotation, excavation and desludging are performed by the stirring blades 6 constituting the lowest stage stirring blade group. The mud S is directed upward and further disintegrated by the stirring blades 6 constituting the stirring blade group in the upper stage. Therefore, the mud S can be finely granulated very efficiently. Furthermore, since the downward pressure due to the mud S and the liquid (including the water W and the liquid L in the water area) stirred by the stirring blades 6 constituting the lowest stirring blade group is relatively small, the lower end of the insertion tube 3 This is advantageous in preventing collapse of the mud S in the non-excavation region R2 blocking the opening 3c.

As in this embodiment, when the pressure sensor 10 is provided, in the step of reciprocating the stirring blade 6 in the tube axis direction after the stirring blade 6 has penetrated to the deepest penetration position D1, the measured value of the pressure sensor 10 It is preferable to adjust the amount of liquid supplied to the inside of the insertion tube 3 per unit time based on. As the amount of liquid supplied to the inside of the insertion tube 3 per unit time is increased, the thawed mud S easily rises to the upper part of the insertion tube 3, which is advantageous for improving the lifting efficiency. On the other hand, when the amount of liquid supplied to the inside of the insertion pipe 3 becomes excessive with respect to the amount of mud S and liquid (including the water W and the liquid L in the water area), the internal pressure of the insertion pipe 3 increases by a predetermined distance T may be greater than the maximum value of the internal pressure of the insertion tube 3 used when setting . Therefore, based on the measurement value of the pressure sensor 10, the pressure of the insertion tube 3 is adjusted so that the lifting efficiency is increased as much as possible within the range not exceeding the maximum value of the internal pressure of the insertion tube 3 used when setting the predetermined distance T. It is preferable to adjust the amount of liquid supplied to the inside per unit time.

If the predetermined distance T can be set so that the lower end opening 3c of the insertion pipe 3 can be blocked by the mud S of the non-excavation region R2 of the waterbed ground B against the internal pressure of the insertion pipe 3, the predetermined distance T can be set. The method is not limited to the methods exemplified above. For example, a preliminary test using the collection system 1 or a simulation using a computer may be performed multiple times while changing the conditions for the predetermined distance T, and an appropriate predetermined distance T may be set based on the test results.

1 Bottom resource sampling system 2 Lifting and collecting pipe 3 Insertion pipe 3a Stopper 3b Lower end 3c Lower end opening 4 Rotating shaft 5 Head 6 Stirring blade 7 Excavating blade 8 Liquid supply mechanism 8a Injection nozzle 8b Piping 9 Strength sensor 10 Pressure sensor 20 Lifting and collecting ship B Submerged ground S Mud L Liquid W Water D1 Deepest penetration position D2 Depth R1 where the lower end of the insertion pipe is located Excavation target area R2 Non-excavation area

Claims (6)

In a method for extracting a bottom-of-water resource by excavating the mud of the bottom-of-water ground containing the bottom-of-water resource and pumping it up to the surface of the water,
A lifting pipe is extended from the water surface toward the waterbed ground, and a liquid is introduced into the insertion pipe in a state in which at least the lower part of the insertion pipe connected to the bottom of the lifting and storage pipe is inserted into the waterbed ground. While supplying, a rotating shaft extending in the tube axial direction inside the lifting and storing tube and the insertion tube, and a stirring blade attached to the lower part of the rotating shaft are rotated inside the insertion tube. excavating and dissolving the mud inside the insertion pipe with the stirring blade, and lifting the slurry of the mud by the dissolution onto the surface of the water through the lifting pipe,
The deepest penetration position of the stirring blade is set above the lower end of the insertion pipe by a predetermined distance, and the lower end opening of the insertion pipe is kept closed with the mud of the waterbed ground, and the slurry slurry is obtained. A method for extracting bottom-of-water resources, characterized by preventing the material from flowing out of the insertion tube through the lower end opening. 2. The method of extracting water bottom resources according to claim 1, wherein said predetermined distance is set based on the strength of said water bottom ground and the pressure inside said insertion pipe inserted into said water bottom ground. 3. The method for extracting water bottom resources according to claim 2, wherein the strength is obtained in advance before inserting the insertion pipe into the water bottom ground. 4. The method of extracting water bottom resources according to claim 2 or 3, wherein the strength is acquired by a strength sensor when the insertion pipe is inserted into the water bottom ground. 5. The method for extracting water bottom resources according to any one of claims 2 to 4, wherein the pressure is calculated and obtained in advance before inserting the insertion pipe into the water bottom ground. 6. The method for extracting water bottom resources according to any one of claims 2 to 5, wherein the pressure is acquired by a pressure sensor after the insertion pipe is inserted into the water bottom ground.

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