JP4637570B2 - Method and system for dewatering sediment from dam lake - Google Patents

Description

  The present invention relates to a dehydration processing method and system capable of stably and efficiently dewatering sediments in a dam lake.

  One of the technologies to effectively use the mixture of water, clay, silt, sand, gravel, etc. (hereinafter referred to as “mud”) generated by dredging sediments in dam lakes and tunnel excavation There is dehydration technology. Among these, mechanical dehydration using a machine such as a screw press is a technique for reducing the volume and increasing the strength of the mud and making it easy to carry and effectively use. As a technique for performing a dehydration treatment of a mud using a screw press, for example, one disclosed in Patent Document 1 is known.

  Patent document 1 is a technology related to recycling sludge generated by dredging. First, mud dredged by a high-concentration dredger is first screened to remove gravel and impurities, and then reacted with a flocculant to floc. After making a dehydrated undiluted solution in which (agglomerated mud) is produced, it is dehydrated by a screw press to separate the drainage to obtain a dehydrated cake. Furthermore, a method is disclosed in which a solidifying agent is added to and mixed with the dewatered cake to form a granular soil.

A screw press is generally composed of a cylindrical or conical outer cylinder (screen) having drainage permeability and a screw shaft on which blades are attached in a spiral shape, and the screw shaft is attached to both end faces of the outer cylinder. It is pivotally supported. The volume of the space between the screw shaft and the outer cylinder is such that the shaft diameter of the screw shaft gradually increases from the dehydrating stock solution inlet side toward the dehydrated cake outlet side, or the outer cylinder diameter gradually decreases. By gradually reducing. As a result, the mud is gradually squeezed with a strong pressure while being sent to the outlet side by the blades, and finally discharged as a dehydrated cake and discharged from the cake outlet while discharging the drainage through the outer cylinder.
JP 2002-192200 A

  By the way, in the above prior art, while the screw press is operated with predetermined specifications and operating conditions (such as the rotational speed of the screw shaft), the properties of the collected mud vary depending on the location. Therefore, there has been a problem that the dehydrated stock solution produced from the mud cannot be stably dehydrated and cannot be efficiently performed.

  Specifically, the content of sand in the dehydrated stock solution, the concentration of mud water (a component obtained by removing sand from the dehydrated stock solution, that is, a mixture of water, clay, and silt), that is, the fine particles contained in the mud water (clay, For example, when the content of sand in the dehydrated stock solution is large (low muddy water content) and the muddy water concentration is high, the rotational speed is too low and clogging occurs in the screw press ( On the other hand, when the content of sand in the dehydrated stock solution is low (high content of muddy water) and the concentration of muddy water is low, the rotational speed is too high and the dewatering is incomplete (incomplete dehydration). Efficiency).

  The present invention was devised in view of the above-described conventional problems, and an object thereof is to provide a method and a system for dewatering a sediment in a dam lake that can stably and efficiently perform a dewatering process. To do.

The dewatering method for sediments in a dam lake according to the present invention is a method for collecting and dewatering mud sediments at the bottom of a dam lake, wherein the “sand content ratio” The ratio of sand to fine particles is determined in advance from the first region, which is higher than the “content ratio”, and the second region, where the “content ratio of fine particles smaller than sand” is higher than the “content ratio of sand”. A mud deposit is collected and mixed to produce a mixed dehydrated undiluted solution at a set ratio, and a dewatering step is performed to dehydrate the mixed dehydrated undiluted solution with a screw press .

Further, the mixing operation in the mud collecting step is performed by simultaneously collecting and mixing the mud deposits from the first region and the second region by a plurality of mud collecting means.

Further, the mixing operation in the mud collecting step is performed by alternately collecting and mixing the mud deposits from the first region and the second region by one mud collecting means. .

  The sediment collection in the mud sampling step is performed sequentially from the surface layer to the deep layer.

The dam lake sediment dewatering system according to the present invention is a system for collecting and dewatering the mud deposits at the bottom of the dam lake, and using a mud collecting means movably provided in the dam lake. The first region where the "sand content ratio" is higher than the "content ratio of fine particles smaller than sand" and the "content ratio of fine particles smaller than sand" is higher than the "sand content ratio" A mud sampling unit that collects mud deposits from the second region so that the ratio of sand to fine particles becomes a predetermined set ratio, and mixes them to produce a mixed dehydrated stock solution, and the mixed dehydration A screw press for dehydrating the stock solution.

  The mud collecting unit includes a plurality of mud collecting means for collecting mud deposits, a plurality of mud collecting pipes for transporting each mud deposit collected by the plurality of mud collecting means, It is connected to a plurality of mud collecting pipes, and has a mixing pipe in which mud deposits from the plurality of mud collecting pipes are mixed and conveyed.

The mud collecting unit conveys the mud deposit collected by the mud collecting means and one mud collecting means for collecting the mud deposit alternately from the first area and the second area. And a mixing section for mixing the mud deposit in the first region and the mud deposit in the second region conveyed by the mud tube. It is characterized by.

  With the method and system for dewatering sediments from a dam lake according to the present invention, dewatering can be performed stably and efficiently.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a method and a system for dewatering sediments from a dam lake according to the present invention will be described in detail with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the dam lake sediment dewatering system 1 according to the present embodiment is basically composed of a mud collecting unit 2 and a screw press 3. In this specification and claims, “sediment” and “mud deposit” are muddy substances deposited on the bottom of a dam lake due to inflow from rivers, etc., and include water, clay, silt. , A mixture containing sand, gravel, etc. Further, “fine-grained portion” refers to clay and silt among particles contained in the mud deposit.

  The mud collecting unit 2 includes two sets of mud collecting means 100 and 101, two mud collecting pipes 102 and 103 for conveying the mud deposits collected by the respective mud collecting means 100 and 101, and these two pipes. Are connected to the mud collecting pipes 102 and 103, and one mixing pipe 104 is provided for receiving and transporting the mud deposits from the mud collecting pipes 102 and 103. The mud collecting means 100, 101 is composed of two dredgers (not shown) that can move in the dam lake D and the mud collecting pipes 100a, 101a of each dredger, and the like, collected from the mud collecting pipes 100a, 101a of each dredger. The mud deposits thus carried are conveyed to the mixing tube 104 through the respective mud collecting tubes 102 and 103. In the mixing pipe 104, the mud deposits from both the mud collecting pipes 102 and 103 are mixed to form a mixed dehydrated stock solution, and then transferred to the vibrating screen 105 in the subsequent stage.

  In this embodiment, two mud collecting pipes 102 and 103 are gathered and connected to one mixing pipe 104, and the mud deposit is mixed inside the mixing pipe 104 to the vibrating screen 105. However, the present invention is not limited to this. That is, for example, the collected mud deposits may be sent individually and directly to the vibrating screen 105 by the mud collecting pipes 102 and 103 connected to the respective mud collecting means 100 and 101. Alternatively, two vibration sieves may be provided individually for each of the mud collecting pipes 102 and 103. In these modifications, in the former case, the mud deposits from the region A and the region C are mixed in the vibrating screen 105, and in the latter case, they are mixed in the storage tank 106. However, as in the present embodiment, the configuration in which the respective mud collecting pipes 102 and 103 are assembled and connected to the single mixing pipe 104 is from the dam lake D to the vibrating screen 105 in comparison with these modifications. The number of pipes and vibrating screens 105 can be reduced, which is more advantageous in terms of cost and securing of piping site.

  As shown in Fig. 2, mud deposits at the bottom of a dam lake contain gravel, sand, fine particles, etc., and these particles generally follow their properties (mass, specific gravity, particle size, etc.). Divided into multiple regions. Looking especially at the particle size, mud deposits at the bottom of a dam lake generally show a certain particle size distribution. In the example shown in the figure, the muddy deposits are distributed in three areas A, B, and C from the surface layer to the semi-deep layer, the upstream part of the river, the middle stream part, and the downstream part close to the dam body T. The mud deposits in region A are gravel (55% gravel, 30% sand, 15% fines), and the mud deposit in region B is sandy soil (5% gravel, 70% sand, fine particles) 25%), the mud deposits in region C have a grain size composition called silty clay (20% sand, 80% fine granule). In the deepest layer of mud deposits, riverbed gravel G is distributed over the entire lake bottom.

  In particular, when attention is paid to sand and fine particles in the mud deposit, the region A which is the upstream portion has a high content ratio of sand, and the region C which is the downstream portion has a high content ratio of fine particles. In the middle stream region B, the content ratio of sand and fine particles is medium. Further, looking at the region B in more detail, in the region B, the upstream content rate is relatively high and the downstream content rate is relatively high.

  Moreover, the deposit state of each area | region AC has a possibility that the accumulation state, ie, particle size distribution, may collapse | crumble by the procedure of a collection | working operation | work, etc. Specifically, for example, if the mud deposits in the region C are collected to a deep level without collecting the mud deposits in the region A and the region B, the region A is affected by the weight and the flow of the river. In addition, the mud deposit in the region B collapses to the portion from which the mud deposit in the region C has been removed, and the particle size distribution of the entire sediment on the lake bottom changes.

The two mud collecting means 100, 101 each have an area where the “sand content ratio” of the mud deposits at the bottom of the dam lake is higher than the “content ratio of fine particles having a smaller diameter than the sand” (hereinafter referred to as “first Area)) and the area where the content ratio of fine particles smaller in diameter than sand is higher than the "content ratio of sand" (hereinafter referred to as "second area"). Muddy deposits are collected so that the ratio is a predetermined ratio.

  In the illustrated example, based on samples collected from each region in advance, the ratio of sand to fine particles contained in the mud deposit located in the central part of region B is set in advance. It is said. Specifications of the screw press 3 used in the dehydration processing system 1 (for example, the volume between the outer cylinder of the screw press 3 and the screw shaft) and the rotational speed of the screw shaft, which is one of the operating conditions of the screw press 3. Is determined to be optimal for this set ratio. In addition, if mud deposits are collected at an appropriate ratio from the upstream region and the downstream region centering on the central portion of the region B, the particle size composition of the mixed dehydrated stock solution mixed with them is determined in advance. It is possible to match the set ratio.

  The vibrating sieve 105 removes gravel from the mixed dehydrated stock solution that has been charged. A pump P1 is provided at the outlet 105a of the vibrating sieve 105, and the remaining mixed dehydrated stock solution from which gravel has been removed is introduced into the cyclone classifier 107 by the pump P1 and centrifuged, and then sent to the storage tank 106. In the cyclone classifier 107, particles adhering to the wall surface by centrifugal separation are returned to the vibrating screen 105 again, thereby more reliably removing gravel remaining in the mixed dehydrated stock solution from the mixed dehydrated stock solution. In the illustrated example, particles having a diameter of 3 mm or more are classified as gravel, particles having a diameter of 74 μm or more and less than 3 mm are classified as sand, and particles less than 74 μm are classified as fine particles. The gravel separated by the vibrating screen 105 is accumulated in the gravel place 41 of the earth and sand pit 4 and is carried out by the backhoe 5 and the bulldozer 6 as needed for various uses.

  The storage tank 106 is provided with a stirrer 108. In the storage tank 106, while receiving and storing the mixed dehydrated stock solution from the cyclone classifier 107, the storage tank 106 is stirred by the stirrer 108 to make the particle size distribution uniform. And send it to the latter part.

  In addition, the storage tank 106 is connected to the aggregated mud water returning means 109, and the aggregated mud water is returned from the aggregated mud water generating unit 7 described later. Agglomerated muddy water is a mixture of fine particles and water, and its amount is very small compared to the mixed dehydrated stock solution introduced from the vibrating sieve 105 side. The dilution water is supplied from the dilution water supply means 110 connected to the storage tank 106, and the ratio of the sand and fine particles contained in the mixed dehydrated stock solution is adjusted to be within a predetermined set ratio range. . The operation of each unit relating to the dilution of the mixed dehydrated stock solution in the storage tank 106 is controlled by the dilution control unit 111. In the illustrated example, the dilution control unit 111 is configured as a part of the control unit 112. Further, a specific gravity measuring device 113 is connected to the storage tank 106, and these dilutions are performed based on the specific gravity of the mixed dehydrated stock solution.

  Further, the storage tank 106 is provided with a stock solution returning means 114 and a stock solution amount control unit 115 in order to adjust the amount of the mixed dehydrated stock solution in the storage tank 106. The stock solution amount control unit 115 is configured as a part of the control unit 112 in the illustrated example. That is, in the illustrated example, the control unit 112 includes the dilution control unit 111 and the stock solution amount control unit 115 described above. The stock solution return means 114 is branched from the discharge pipe 116 of the storage tank 106 and is connected to the receiving port 105b of the vibrating screen 105, and a valve V1 that can be opened and closed provided in the middle of the stock solution return pipe 114a. And a stock solution amount measuring device 114b that is provided in the storage tank 106 and measures the amount of the mixed dehydrated stock solution in the storage tank 106, and the stock solution amount in the storage tank 106 is set to a reference value by supplying dilution water or the like. In the case of exceeding, an appropriate amount of the mixed dehydrated stock solution is returned to the vibrating screen 105 by the stock solution returning means 114.

  Specifically, first, the stock solution amount measurement value measured by the stock solution amount measuring device 114b is output to the stock solution amount control unit 115, and the stock solution amount control unit 115 determines that the stock solution amount measurement value has reached a reference value or more. In this case, the stock solution amount control unit 115 opens the valve V1 and closes a valve V2 provided in the middle of the stock solution transport pipe 8 described later, and then operates the discharge pump P2 of the storage tank 106. As a result, the mixed dehydrated stock solution in the storage tank 106 is returned to the receiving port 105 b for the vibrating screen 105. The stock solution amount control unit 115 automatically ends the return after returning the mixed dehydrated stock solution for a predetermined period. Alternatively, the return may be terminated when the measured value of the stock solution output from the stock solution measuring device 114b is lowered to a predetermined value.

  By providing such a stock solution returning means 114 for returning the mixed dehydrated stock solution in the storage tank 106 and a stock solution amount control unit, the mixed dehydrated stock solution in the storage tank 106 does not overflow, and an appropriate fixed amount. In addition, the mixed dehydrated undiluted solution in the storage tank 106 is circulated again in the dehydration treatment system 1 to more reliably and efficiently remove gravel remaining in the returned mixed dehydrated undiluted solution. can do.

  In addition, a stock solution transport tube 8 for sending the mixed dehydrated stock solution to the subsequent stage is connected to the discharge pipe 116 of the storage tank 106. The stock solution transfer pipe 8 is connected to a paddle reactor 9 described later, and a valve V2 that can be controlled to open and close is provided in the middle thereof. When the mixed dehydrated stock solution is transported from the storage tank 106 to the paddle reactor 9, the above-described stock solution volume control unit 115 opens the valve V2 and closes the valve V1 of the stock solution return means 114. Then, the discharge pump P2 is operated.

  In the paddle type reactor 9, flocs are generated by reacting the fed mixed dehydrated stock solution with one or more kinds of flocculants 10 such as anions and cations, and particles in the mixed dehydrated stock solution are transferred to the screw press 3. Adjust so that it is difficult to discharge from the outer cylinder.

  The screw press 3 includes a cylindrical or conical outer cylinder (screen) having drainage permeability, and a screw shaft on which blades are spirally attached. The screw shaft is freely rotatable on both end faces of the outer cylinder. Is pivotally supported. The volume of the space between the screw shaft and the outer cylinder is such that the shaft diameter of the screw shaft gradually increases from the mixed dehydrating stock solution inlet 31 side toward the dehydrated cake outlet 32 side, or the outer cylinder diameter is Reduce gradually by gradually reducing. As a result, the mixed dehydrated undiluted solution is gradually squeezed with a strong pressure while being sent to the outlet 32 side by the blades, and finally discharged as a dehydrated cake and discharged from the cake outlet 32 while discharging the drainage through the outer cylinder. .

  In the subsequent stage of the screw press 3, a sludge storage 12 is provided via a thickener 7 a as the agglomerated muddy water generation unit 7 and a belt conveyor 11. The dewatered cake is accumulated in the sludge storage area 12.

  In the thickener 7a, the waste water discharged from the outer cylinder of the screw press 3 is received and subjected to agglomeration treatment with one or more kinds of appropriate aggregating agents 13 such as polysodium chloride (PAC) and organic polymer type aggregating agent. As a result, fine particles such as clay and silica slightly remaining in the wastewater are agglomerated and precipitated, and a liquid containing this precipitate (hereinafter referred to as agglomerated mud water) is taken out from the discharge port 7b below the thickener 7a. In the illustrated example, the thickener discharge port 7 b is connected to the aggregated mud return means 109, and the aggregated mud is returned to the storage tank 106. In addition, the supernatant liquid which is the remainder of the aggregation process in thickener 7a is discharged | emitted suitably, such as returning to the dam lake D.

  By providing the agglomerated mud water generating unit 7 and the agglomerated mud water returning means 109 as described above, the waste water from the screw press 3 can be circulated again in the dehydration treatment system 1, and particles remaining in the waste water slightly. It can be removed more reliably and efficiently.

Next, a method for dewatering a deposit in such a dam lake will be described using the dewatering system 1 as an example. In the mud collecting step, first, in the dam lake D, mud deposits on the lake bottom are collected simultaneously by the two mud collecting means 100 and 101. In the illustrated example, in particular, paying attention to the particle size distribution of the mud deposit, as shown by the arrow in FIG. 2, in one of the mud collecting means 100, in the area A (first area) where the sand content ratio is the highest. In the other mud collecting means 101, the collection of the mud deposit is started in the region C (second region) in which the content ratio of the fine particles is the highest. More specifically, one of the mud collecting means 100 starts collecting from the most upstream point in the area A, and the other mud collecting means 101 starts collecting from the most downstream point of the area C, and then each of the mud collecting means 100 and 101 is sanded together. In the region B where the content ratio of fine particles is medium, the sample is collected while moving continuously, particularly toward the center.

  Furthermore, in the present embodiment, not all the mud deposits in the region A and the region C are collected first, but sequentially from the surface layer to the deep layer. Specifically, first, a mud deposit on the surface layer is collected while moving from region A to region B by one mud collecting means 100 and from region C to region B by the other mud collecting means 101. Thereafter, the middle-level mud deposit is collected while moving in the direction opposite to that in the case of the surface layer while moving from region B to region A in one mud collecting means 100 and from region B to region C in the other mud collecting means 101. To do. Finally, the deep mud is collected while moving in the same direction as the surface of the mud. In the present embodiment, the deepest riverbed gravel G is not collected. In addition, it is not necessarily limited to the method of dividing into three layers such as the surface layer, the middle layer, and the deep layer as in this embodiment, and it is possible to collect from the surface layer to the deep layer sequentially after dividing into more layers. Good.

  In the mud collecting step, mud deposits collected by the two mud collecting means 100 and 101 are then sent from the respective mud collecting pipes 102 and 103 to the mixing pipe 104 and mixed inside the mixing pipe 104, The mixed dehydrated stock solution is added to the receiving port 105b of the vibrating sieve 105, and the gravel is removed. The mixed dehydrated undiluted solution from which the gravel has been removed is centrifuged in a cyclone classifier 107, and the separated particles are returned to the vibrating screen 105 again before being sent to the storage tank 106.

  Next, the mixed dehydrated stock solution charged into the storage tank 106 is stirred by the stirrer 108 so that the particle sizes are uniform. The agglomerated muddy water is returned from the agglomerated muddy water generating unit 7 to the storage tank 106 by the agglomerated muddy water returning means 109 as needed. When the mixed dehydrated stock solution needs to be diluted, the dilution control unit 111 operates the pump P3 of the dilution water supply means 110 to supply the dilution water. In addition, when the amount of the mixed dehydrated stock solution in the storage tank 106 exceeds the reference value and is likely to increase too much, both the undiluted solution so that an appropriate amount of muddy water is returned to the vibrating screen 105 by the stock solution returning means 114. It is controlled by the control unit 115.

  Next, the mixed dehydrated stock solution is introduced into the paddle reactor 9 from the storage tank 106 through the stock solution transport pipe 8. In the paddle reactor 9, the mixed dehydrated stock solution is reacted with the flocculant 10 to generate floc.

  Next, the mixed dehydrated stock solution in which the flocs are generated is charged into the screw press 3, and a dehydration step is performed. In the screw press 3, the charged mixed dehydrated stock solution is sent to the cake outlet 32 side while being compressed by the rotation of the screw shaft, and the dehydrated cake is discharged from the cake outlet 32.

  Further, in the dehydration step, the drainage discharged from the outer cylinder of the screw press 3 is sent to a thickener 7 a serving as an agglomerated muddy water generating unit 7. In the thickener 7a, the flocculant 13 is added to and mixed with the above-mentioned wastewater to perform the agglomeration treatment. As a result, the fine particles remaining in the wastewater are agglomerated and settled, and a liquid (aggregated muddy water) containing this precipitate is taken out from the discharge port 7b of the thickener 7a, and the agglomerated muddy water returning means 109 connected to the discharge port 7b. Is sent to the storage tank 106.

In the method and system for dewatering sediments in the dam lake according to the present embodiment described above, the mud collecting means provided movably in the dam lake D in the mud collecting step in the mud sampling unit 2. 100, 101, the mud deposits at the bottom of the dam lake are sanded from the first region (up to the upstream half of region A and region B) and the second region (region C and the downstream half of region B). The mixture was collected so that the ratio between the fine particles and the fine particles was a predetermined ratio, mixed to produce a mixed dehydrated stock solution, and then dehydrated in a dehydration step using a screw press. As a result, clogging occurs in the screw press 3 or the dehydration is incomplete by dehydrating the mixed dehydrated stock solution having the optimum content ratio of sand and fine particles with respect to the specifications and rotation speed of the screw press 3 The dehydration process can be performed stably and efficiently.

In particular, in the present embodiment, the mixing operation of the mud deposits in the mud sampling step is performed by collecting the mud deposits from the first region and the second region simultaneously by the two mud sampling means 100 and 101. Since, for example, only one mud collecting means is used, sampling is alternately performed from the first region and the second region. The entire dehydration process including can be performed faster, for example, about twice as fast.

  In addition, the collection of mud deposits in the mud sampling step is performed in order from the surface layer to the deep layer in the order of surface layer → middle layer → deep layer. At that time, the other area collapses, the particle size distribution of the entire sediment on the lake bottom changes, and there is no possibility that the subsequent sampling locations cannot be properly positioned. As a result, it is possible to systematically collect mud deposits having a constant particle size distribution, and the dehydration process can be performed more stably and efficiently.

  In the above embodiment, the two mud collecting means 100 and 101 are used in the mud collecting step in the mud collecting unit 2, but the present invention is not limited to this, and more mud collecting is performed. Means may be used. Even in such a case, the same operations and effects as those of the above-described embodiment can be obtained, and further, the entire dehydration process including the mud deposit collecting step can be performed faster. In this case, the mud deposits collected by each mud collecting means are sent to a vibrating screen or a storage tank through a mud collecting pipe connected to each mud collecting means and mixed with each other. However, if each mud collecting pipe is gathered and connected to one or a few mixing pipes, and mud deposits are mixed and transported inside it, from the dam lake D to the vibrating screen The number of pipes and the like can be reduced, which is more advantageous in terms of cost and securing of piping site.

  Further, in the above embodiment, in the mud collecting step in the mud collecting unit 2, the mud deposit is continuously collected while moving the two mud collecting means 100, 101. It is not limited. That is, when the dam lake D is relatively narrow, each of the areas A, B, and C is also relatively small in area, and therefore, one mud collecting means 100 is first fixed near the center of the area A to form a mud deposit. At the same time, the other mud collecting means 101 is fixed in the vicinity of the center of the region C to collect the mud deposit, and then either one of the mud collecting means or both of the mud collecting means 100, 101 are attached. It may be a procedure of collecting the mud deposit fixed near the center of the region B. In this case, based on the samples collected from each region in advance, the average particle size composition of the mud deposits in the region B is set to a predetermined setting ratio, and an appropriate ratio is determined from the regions A and C. If the mud deposits are collected, the particle size composition of the mixed dehydrated undiluted solution in which they are mixed can be made to coincide with a predetermined set ratio. Also in the case of such a sampling method, it is preferable to sequentially collect the muddy deposits from the three regions from the surface layer to the deep layer as in the above embodiment.

FIG. 3 shows a modified example of the above-described embodiment. In this modified example, the mud sampling unit 2 of the dehydration processing system 1 is alternately deposited in a mud from the first region and the second region. One mud collecting means 150 for collecting the object, one mud collecting pipe 151 for conveying the mud deposit collected by the mud collecting means 150, and a first area conveyed by the mud collecting pipe 151 A mixing unit for mixing the mud deposit and the mud deposit in the second region ; Specifically, the storage tank 31 constitutes a mixing unit.

More specifically, sand is first contained by a mud collecting means 150 including a dredger (not shown) and a mud pipe 150a as shown by circled numbers 1 → 2 → 3 in FIG. Collect the mud deposits in the area A (first area) with a high ratio and then collect the mud deposits in the area C (second area) with a high content of fine particles. Collected alternately from region A (first region) with a high content ratio and region C (second region) with a high content ratio of fine particles, and finally the content ratio of sand and fine particles is medium. Collect area B mud deposits.

  Even in the illustrated example, the average particle size configuration of the mud deposits in the region B is set to a predetermined setting ratio based on the samples collected from each region in advance, and the region A and the region C Therefore, if the muddy deposits are collected at an appropriate ratio, the particle size composition of the mixed dehydrated stock solution in which they are mixed can match the preset ratio.

  In this modified example, the dehydration processing system 1 requires only one mud collecting tube 151 and does not require a mixing tube. The collected mud deposits are mixed in a storage tank 106 as a mixing unit. That is, the mud deposit collected by the mud collecting means 150 is sent directly from the mud collecting pipe 151 to the vibrating screen 105 and the storage tank 106.

  First, the muddy deposits collected from the area A of the dam lake D are accumulated in the storage tank 106, and then the muddy deposits collected from the area C are charged, and both are mixed in the storage tank 106. A mixed dehydrated stock solution is produced. Next, in the dam lake D, the mud collecting means 150 is moved to the region B, and in the meantime, the mixed dehydrated stock solution is stirred by the stirrer 108 in the storage tank 106 and then sent to the subsequent stage. Next, in the dam lake D, a muddy deposit is collected from the region B, and this muddy deposit is sent to the vibrating sieve 105 and the storage tank 106 through the mud collecting pipe 151, and this is agitated alone. , Sent to the latter stage. Also in this modified example, it is preferable to sequentially collect the muddy deposits from the three regions from the surface layer to the deep layer as in the above embodiment.

  Even in this modification, it is a matter of course that the same operations and effects as those of the above-described embodiment can be obtained. In particular, in this modification, only one mud collecting means such as a dredger is required, which is further advantageous in terms of cost.

  It should be noted that the properties of the particles constituting the mud deposits at the bottom of the dam lake, in particular, the particle size thereof, are not necessarily distributed in three regions as in the above embodiment and modification, and are not necessarily upstream of the river. Even if the particle size distribution of the mud deposit is different from that of the present embodiment, it shows a certain particle size distribution with sand, fine particles, etc. If so, the dehydration method and the dehydration system of the present invention can be applied in the same manner, and have the same actions and effects as the above-described embodiment and modification.

It is explanatory drawing which shows suitable one Embodiment of the dehydration processing system for enforcing the dehydration processing method of the deposit of a dam lake concerning this invention. It is explanatory drawing which shows the state of the muddy deposit in a dam lake, and its extraction of the dehydration processing system of FIG. It is a modification of the dewatering processing system for enforcing the dewatering processing method of the sediment of the dam lake concerning this invention, Comprising: It is explanatory drawing which shows the extraction in a dam lake corresponding to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dehydration processing system 2 Mud sampling part 3 Screw press 100, 101, 150 Mud collecting means 102, 103, 151 Mud collecting pipe 104 Mixing pipe D Dam lake

Claims (7)

A method of collecting and dewatering mud deposits at the bottom of a dam lake,
The first region where the “content ratio of sand” is higher than the “content ratio of fine particles smaller than sand” and the “content ratio of fine particles smaller than sand” is higher than the “content ratio of sand”. A mud sampling step in which the mud deposits are collected from the two regions so that the ratio of sand to fine particles is a predetermined ratio, and mixed to produce a mixed dehydrated stock solution;
A method for dewatering a sediment in a dam lake, comprising: a dewatering step of dewatering the mixed dewatered stock solution with a screw press. The mixing operation in the mud collecting step is performed by collecting and mixing mud deposits simultaneously from the first area and the second area by a plurality of mud collecting means. A method for dewatering sediments from the dam lake. The mixing operation in the mud collecting step is performed by alternately collecting and mixing mud deposits from the first area and the second area by one mud collecting means. 2. A method for dewatering a sediment of a dam lake according to 1. The method for dewatering sediments from a dam lake according to any one of claims 1 to 3, wherein the collection of sediments in the mud collecting step is sequentially performed from a surface layer to a deep layer. A system for collecting and dewatering mud deposits at the bottom of a dam lake,
Due to the mud collection means movably installed in the dam lake, the first area where the “sand content ratio” is higher than the “content ratio of fine grains smaller than sand” and the “fine grain fraction smaller than sand” From the second region where the “content ratio” is higher than the “sand content ratio” , the muddy sediment is collected and mixed so that the ratio of sand to fine particles becomes a predetermined ratio. A mud collecting section for producing a mixed dehydrated stock solution;
A dam lake sediment dewatering system comprising a screw press for dewatering the mixed dehydrated stock solution.   The mud collecting unit includes a plurality of mud collecting means for collecting mud deposits, a plurality of mud collecting pipes for conveying each mud deposit collected by the plurality of mud collecting means, and the plurality of mud collecting pipes. 6. A dewatering treatment for sediments in a dam lake according to claim 5, further comprising a mixing pipe connected to the mud pipes, wherein the mud deposits from the plurality of mud pipes are mixed and conveyed. system. The mud collecting part conveys the mud deposit collected by one mud collecting means for collecting the mud deposit alternately from the first area and the second area, and the mud collecting means. And a mixing unit for mixing the mud deposit in the first region and the mud deposit in the second region conveyed by the mud tube. The dewatering treatment system for sediments in a dam lake according to claim 5.

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