JPH0759171B2 - Manufacture method of artificial fishing reef - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an artificial fishing reef using dredged mud as a raw material.

[Prior art]

Sediment at the bottom of the sea or lake is dredged for the purpose of maintaining appropriate water depth, preventing pollution, and installing subsea structures.In this case, the obtained dredged mud is stored in a vast reservoir mud. Transported and stored. However, since such dredged mud contains a rotten organic substance, it has a problem that it produces a bad odor and adversely affects the living environment. Particularly, in a fish farm, the bait given to the fish is not fully digested and is deposited on the bottom of the water as it is, spoils, and adversely affects the cultured fish. Therefore, in such a fish farm, it is necessary to dredge the water bottom, but in this case, there is a problem in the treatment of dredged mud.

On the other hand, it has been conventionally known that concrete blocks and the like are put into water as fishing reefs in order to breed fish and algae. However, in the case of concrete blocks, there are problems such as high production costs and long-term curing to obtain blocks of the required strength, and there is a need for the development of inexpensive and efficient fishing reefs. ing.

〔Purpose〕

It is an object of the present invention to solve the above-mentioned problems found in the treatment of dredged mud from the sea or the bottom of water such as lakes and marshals, and to provide an inexpensive method for producing artificial reefs.

〔Constitution〕

As a result of intensive studies to achieve the above-mentioned object, the present inventors have obtained a solidified product obtained by treating mud containing an organic substance dredged from the bottom with a solidifying agent, which has excellent performance as a fishing reef. In addition to finding out that it has, and by effectively using the dredged mud that was previously regarded as a pollutant that is difficult to treat as a material for fishing reefs, the problems of the treatment of dredged mud and the cost reduction of artificial fishing reefs described above can be solved at once. Therefore, they have completed the present invention.

That is, according to the present invention, the following treatment agent (A) or (B) additive [I] is added to the dredged mud, and the colloid component in the mud is condensed / aggregated, and then dehydrated to give the soil. particle
A soil particle slurry containing at least 5 parts by weight of gypsum and 50 to 400 parts by weight of water per 100 parts by weight is formed, and then (i) an additive [II] of the following treating agent A is added to the soil particle slurry. 2 to 20 per 1 part by weight of gypsum contained in the soil particle slurry
A soil particle slurry containing the treating agent A is obtained by adding and mixing in a proportion of parts by weight, or (ii) an additive for the following treating agent B [II]
The ratio of the additive [II] to the total amount of the fine blast furnace slag contained in the soil particle slurry and the additive [II] is 40.
A method for producing an artificial fishing reef is provided, which comprises adding and mixing so as to be about 55 wt% to obtain a soil particle slurry containing the treating agent B, and then solidifying the soil particle slurry into a required shape. It

Treatment agent (A) Additive [I]: Gypsum Additive [II]: Portland cement 40-55% by weight and fine blast furnace water slag 60-45% by weight Treatment agent (B) Additive [I]: Gypsum And fine blast furnace slag, CaSO
₄ Mixture having a content of 10 to 50% by weight Additive [II]: Portland cement Further, according to the present invention, the additive [I] of the following treating agent A or B is added to the dredged mud and left to stand. Then, after phase separation into a lower layer consisting of a soil particle slurry phase containing at least 5 parts by weight of gypsum per 100 parts by weight of soil particles contained in the mud and an upper layer consisting of an aqueous phase, the obtained soil particle slurry is (I) Dehydrated to obtain a soil particle slurry having a water content of 50 to 400 parts by weight per 100 parts by weight of the soil particles, and the additive [II] of the following treating agent A is added to the soil particle slurry. 2 to 20 parts by weight per 100 parts by weight of the contained soil particles are added and mixed to obtain a soil particle slurry containing the treating agent A, or (ii) the following additive [II] of the treating agent B is added to the soil particles. Additive [II] to the total amount of fine blast furnace slag contained in the slurry and the additive [II] After adding and mixing so that the ratio of 40 to 55%, the mixture is dehydrated and the soil particles 10
A method for producing an artificial fishing reef, characterized in that a soil particle slurry containing a treated part B having a ratio of water per 0 part by weight of 50 to 400 parts by weight is obtained, and then the soil particle slurry is solidified into a required shape. Will be provided.

Treatment agent (A) Additive [I]: Gypsum Additive [II]: Portland cement 40-55% by weight and fine blast furnace water slag 60-45% by weight Treatment agent (B) Additive [I]: Gypsum And fine blast furnace slag, CaSO
₄ Mixture whose content is 10 to 50% by weight Additive [II]: Portland cement Further, according to the present invention, a flocculant is added to the dredged mud,
After allowing to stand, and phase-separating into a lower layer consisting of a soil particle slurry phase and an upper layer consisting of an aqueous phase, the obtained soil particle slurry is subjected to (i) dehydration treatment and water per 100 parts by weight of the soil particles. The ratio is 50 to 400 parts by weight of soil particle slurry, and this soil particle slurry consists of gypsum, Portland cement and fine blast furnace slag, and the total amount of Portland cement and blast furnace slag per 1 part by weight of gypsum is 2 to 20 parts by weight, the proportion of Portland cement to the total amount of Portland cement and blast furnace water slag is 40 to 55% by weight, and the proportion of blast furnace water slag is 60 to 45% by weight, a solidifying agent Gypsum is added and mixed in an amount of at least 5 parts by weight per 100 parts by weight of soil particles in the slurry to obtain a soil particle slurry containing a solidifying agent, or (ii) gypsum and Portland cement Fine high It consists of reactor water slag, and the total amount of Portland cement and blast furnace slag is 2 to 20 parts by weight per 1 part by weight of gypsum, and the ratio of Portland cement to the total amount of Portland cement and blast furnace slag is 40 to 55. Weight% and blast furnace slag ratio 60
~ 45 wt% solidifying agent is added and mixed so that the amount of gypsum added is at least 5 parts by weight per 100 parts by weight of the soil particles in the soil particle slurry. Dehydration treatment is performed to obtain a soil particle slurry containing a solidifying agent having a water content of 50 to 400 parts by weight per 100 parts by weight of the soil particles, and then the soil particles containing the solidifying agent thus obtained. There is provided a method for producing an artificial fishing reef, which comprises solidifying a slurry into a required shape.

The dredged mud used as the artificial fishing reef material in the present invention is a mud containing a large amount of water obtained during dredging work on the sea, lakes and rivers, and contains an organic substance.

In addition, in this specification, regarding the dredged mud containing seawater, what is obtained by removing salts dissolved in seawater is treated as soil particles. In the measurement of the water content by the method of JIS 1203-1978, salts dissolved in seawater will be incorporated into the soil particle content, but in the present invention, in order to avoid this, the dredged mud soil is the soil particle content ( Insoluble solids) and seawater.

In the present invention, one of the materials for the above treatment agent (solidifying agent)
Portland cement used as
What conforms to JIS R5210, but generally conforms to ordinary Portland cement among them.
However, depending on the case, Portland cements according to the standards such as moderate heat Portland cement, early heat Portland cement, and super early strength cement may be used alone or in combination.

Fine blast furnace water slag, which is one of the materials for the treating agent, is a slag that is a by-product of the blast furnace for iron making, that is, a slag is rapidly cooled with water and crushed into sandy or granular granules of about 1 to 5 mm. The slag (herein referred to as blast furnace water slag) is further treated with a particle size of 100
It is finely pulverized to 1 μm. The weight composition is slightly different depending on the composition of the iron ore and the operating method of the blast furnace, but is approximately as follows.

_{SiO 2: 30~35%, Al 2} O 3: 13~18%, CaO: 38~45%, Fe
₂ O ₃ : 0.5 to 1.0%, MgO: 3 to 6%, S: 0.5 to 1.0%, MnO: 0.5
~ 1.5%, TiO ₂ : 0.5-1.0%.

Since this fine blast furnace water slag is used as a reaction agent, it is essential that it has latent hydraulicity capable of exhibiting hydraulicity by the stimulating action of an alkali or the like. Therefore, it is important to rapidly cool the slag and to make the slag crystallize, thereby preserving the crystallization energy inside and making it an amorphous (glassy) one, and then pulverizing it. . If the rapidly cooled slag has a low vitrification rate, it produces less hydrate due to the alkali stimulating action and is inferior in the action and effect as a reaction agent. In other words, the blast-furnace slag crushed stone obtained by gradually cooling the slag is crystalline and has no latent hydraulicity, so it is impossible to achieve the purpose even if it is pulverized and used as a treatment agent material. Is. Further, the use of 1 to 5 mm coarse-grained blast furnace water slag as a raw material causes the reactivity to be remarkably lowered because the surface area contributing to the reaction is too small. Therefore, it is preferable to use a fine blast furnace slag having a high vitrification rate and a particle size of 100 to 1 μm.

As gypsum, which is one of the materials for the treating agent, dihydrate gypsum or insoluble anhydrous gypsum (including type II anhydrous gypsum and hard gypsum) is used. However, in some cases, hemihydrate gypsum or soluble anhydrous gypsum may be used in place of some of these gypsums. In the case of dihydrate gypsum, the particle size is not particularly limited and may be powder or granules. In the present invention, natural gypsum and various chemical gypsum produced as by-products from various processes can be used. Flue gas desulfurization gypsum should be used in the form in which it is recovered without adding secondary processes such as drying or washing the product that was finally separated and collected from the centrifuge in the process. You can also When insoluble anhydrous gypsum is used, its particle size is 100 because of its dissolution rate.
It is preferable that the powder has a particle size of not more than μm. In the present invention,
Insoluble anhydrous gypsum (hydrofluoric acid gypsum), which is a by-product when hydrogen fluoride is produced by thermally decomposing fluorspar with concentrated sulfuric acid, can be directly used. It is gypsum hydrofluoride particle size
This is because it is produced as a dry powder of 100 μm or less.

Next, in the method of the present invention, the case of producing a fish reef using the treatment agent (A) comprising the additive [I] and the additive [II] will be described in detail first.

First, the additive [I] (gypsum) is added to the dredged mud. In this case, the addition of the additive [I] to the dredged mud can be carried out by various methods. For example, when pumping the dredged mud from the dredged area to the sedimentation basin with a pump, the additive [I] is added to the transportation pipe in a slurry form, or the additive [I] is added in a slurry form or in the sedimentation basin. A method such as addition in powder form can be performed.
The amount of the additive [I] added to the dredged mud is a ratio equal to or higher than the solubility of gypsum (about 0.2% by weight in terms of CaSO _{4 in} water), and the soil obtained in the subsequent dehydration treatment or sedimentation treatment step. The amount of gypsum contained in the particle slurry is at least 5 parts by weight per 100 parts by weight of soil particles. When the sole purpose is to settle the dredged mud, only a small amount of gypsum may be added because the effect of gypsum is only the coagulation effect.
However, in order to dehydrate and solidify the dredged mud,
It is necessary to coexist at least 5 parts by weight per 100 parts by weight of the soil particles of the soil particle slurry. The preferable addition amount is (a) the type and pH value of the dredged mud soil, (b) the content and quality of the soil particle content, (c) the water content of the soil particle slurry to be prepared,
(D) Value of desired strength of solidified product, (e) Other, molding
Differs depending on requirements such as solidification method. Examples of the quality of soil particles include the type of clay mineral, the amount of fine particles and the state of particle size distribution, the types of organic compounds and phosphate compounds contained, and their contents. Further, the water content of the prepared soil particle slurry has a great influence on the strength of the solidified product when the other conditions (a), (b), (d) and (e) are the same. Therefore, it is difficult to uniformly determine the optimum amount of gypsum to be added, but the preferred amount of gypsum generally used is 5 to 25 parts by weight per 100 parts by weight of the soil particles in the soil particle slurry. .

Next, the dredged mud containing the additive [I] added and mixed
(A) After the colloidal content in the dredged mud is condensed and aggregated, it is dehydrated by a centrifugal dehydrator, or (a) it is left as it is to sediment the soil particles suspended in the dredged mud, After removing the separated aqueous phase, dehydration treatment is performed. At this time,
It is desirable to coexist with sodium chloride. The coexistence of this sodium chloride can further increase the sedimentation rate of suspended soil particles. That is, in the case of the present invention, by adding gypsum as an additive [I], sedimentation and centrifugal dehydration of the soil particles are remarkably promoted by the action of coagulation and agglomeration of the gypsum on the colloids of the soil particles, which is remarkably shortened. It is possible to obtain a soil particle slurry having a soil particle content rate of 13 to 25% by weight at the specified time. At this time, if a small amount of sodium chloride (0.01 to 4% by weight with respect to the water of the dredged mud) is added, The sedimentation separation effect of the soil particle slurry is improved. Further, the solidification time by the addition / mixing treatment of the additive [II] in the soil particle slurry can be further shortened.

As described above, the amount of gypsum constituting the additive [I] may be small if only the soil particles suspended from the dredged mud are allowed to settle, but in order to solidify the sedimented soil particles, As described above, it is important to define the addition amount of gypsum that constitutes the additive [I]. That is, in the case of the present invention, this additive [I] exhibits an action as a coagulating / aggregating agent for suspended soil particles in the sedimentation treatment step, but the subsequent additive [II]
In the step of solidifying the sedimentary soil particles by the addition of, it acts as a reaction agent for the additive [II]. Therefore, in consideration of the role as a reaction agent for the additive [II], molding /
The optimum addition amount is determined according to the strength required for the solidified material.
The required strength of the molded / solidified product is determined by its purpose, but as a general required strength, the uniaxial compressive strength is at least 10 kgf / cm ² or more, preferably 20 to 200 kgf / cm.
^It is good to specify in the range of ² .

When the soil particle slurry containing the additive [I] is subjected to a sedimentation treatment, suspended soil particles are sedimented, and the soil particle slurry is an aqueous phase forming an upper layer and a concentrated soil particle slurry forming a lower layer. Phase separate into phases. In this case, the soil particle slurry phase contains a high concentration of soil particles, and the volume of the soil particle slurry phase decreases with the passage of standing time, but this is practically used as a molded solidified product having desired strength. Therefore, it is necessary to perform dehydration treatment. Coagulates the colloidal content of dredged mud
Only by aggregating and allowing to stand, not only it takes a long time to bring the soil particle slurry phase to the desired soil particle concentration, but
Most dredged muds do not reach their desired soil particle concentration over time. Therefore, add the additive [I]
As described above, the mixed dredged mud is dehydrated by a centrifugal dehydrator after (a) the colloidal content in the dredged mud is condensed or aggregated, or (b) it is left as it is to remove the soil particle content. After settling and removing the separated aqueous phase, dehydration treatment is performed. By the dehydration treatment, the dehydrated product has a water content suitable for molding and solidification. The optimum amount of water differs depending on the consistency of the mixture of the soil particles and the solidifying agent (treatment agent) and the method of molding / solidifying. Generally, the optimum amount of water is 50 to 400 parts by weight per 100 parts by weight of soil particles, 100 to 400 parts by weight for casting, and 50 to 200 for pressing.
Weight part (depending on the press pressure).

The additive [II] can be added and mixed to the dehydrated product, and in some cases, can be added and mixed to the soil particle slurry prior to the dehydration treatment. In addition, the dredged mud is
Just by directly applying it to the dehydrator, the dehydration treatment cannot be performed as efficiently as when the additive [I] of the present invention is added.

As the dehydration method, a conventionally known solid-liquid separation method, for example,
A centrifugation method or a filtration method is adopted. When the colloid component in the dredged mud is condensed and aggregated and then immediately dehydrated, the dehydration by the centrifugal separation method is very effective.

The additive [II] added to the soil particle slurry containing the additive [I] concentrated by dehydration consists of a mixture of Portland semetons and fine blast furnace slag. In this case, the Portland semes in the additives [II] 40-55% by weight
Also, the proportion of fine blast furnace slag should be 60 to 45% by weight. By the addition of the additive [II], a reaction occurs between the materials of the additives [I] and [II] and the fine soil particles, and the soil particle slurry is solidified. This solidification reaction includes cation exchange reaction of fine soil particles, ettringite [3CaO ・ Al ₂ O ₃・ 3CaSO ₄・ 28-32H ₂ O] formation reaction, tobermorite mineral-like phase [3CaO ・ SiO ₂・3H ₂ O] and the like, and a non-gelling substance formation reaction by various reactions.

When solidifying the soil particle slurry as described above,
In the soil particle slurry, the additive [I] is uniformly dispersed in the slurry, and in addition, harmful substances such as humic acid and other harmful substances which adversely affect the hydration reaction of Portland cement and harmful substances such as phosphate are added to the additive [I]. Since it is masked by the gypsum, which is the material of, the solidification reaction can occur extremely efficiently. Therefore, in the solidification treatment using the additive [II], it is possible to remarkably improve the overall treatment efficiency in combination with the use of the additive [I] in the preceding step. It is effective to define the amount of the additive [II] to be 2 to 20 parts by weight, preferably 3 to 10 parts by weight, per 1 part by weight of gypsum contained in the soil particle slurry. is there.

Molding and solidification methods are roughly divided into casting method and press molding method, but the processing by the press generation method requires less solidifying agent than the casting method, The strength of the solidified product is rapidly developed, and the final strength is large. The solidified material may have any shape as long as it is suitable for fishing reefs. For example, it is possible to provide a fishing reef simple substance in which a hollow regular hexahedron, a cylindrical type with a hollow window, and a block shape such as a plate shape, a square shape, and a column shape are combined.

Although the example of treating the dredged mud using the treatment agent (A) has been described above, the treatment may be performed in other steps.
For example, after the additive [I] is added to the dredged mud to perform phase separation into an aqueous phase forming the upper layer and a soil particle slurry phase forming the lower layer, the additive [II] (Portland semé) is added to the obtained soil particle slurry. Blast furnace water slag mixture)
It is also possible to dehydrate the obtained mixture, mold it into a required shape, and solidify it. Further, when the treatment agent (B) is used, it can be carried out in the same manner as in the case of the treatment agent (A). In this case, the additive [I] constituting the treating agent (B)
Is composed of a mixture of gypsum and fine blast furnace slag, and the additive [II] is different from the treatment agent (A) in that it is composed of Portland cement. Therefore, the addition amounts of the additives [I] and [II] in this case are naturally different from those in the case of the treatment agent (A). But,
The respective material ratios of the additives [I] and [II], in other words, the use ratios of gypsum, fine blast furnace slag and Portland cement are the same as those when the treating agent (A) is used. That is, with respect to the total amount of fine blast furnace slag in the additive [I] and Portland cement of the additive [II],
Additive [I] and additive [II] may be added so that the proportion of Portland cement is 40 to 55% by weight and the proportion of fine blast furnace slag is 60 to 45% by weight. The ratio of gypsum and fine blast furnace slag in the additive [I] of the treating agent (B) can be variously changed depending on the type of the dredged mud, but generally, The content of gypsum is 10 to 50% by weight, preferably 15 to 40% by weight in terms of CaSO ₄ . In other words, the content of the additive [I] in the fine blast furnace slag is 90 to 50% by weight, preferably 85 to 60% by weight.

In the present invention, when the coagulation / aggregation treatment of the colloid is performed using the additive [I] in the treatment agent (A) or (B),
As described above, it is advantageous to add sodium chloride to the dredged mud as an auxiliary component. This auxiliary component significantly improves the efficiency of sedimentation of soil particles and centrifugal dehydration, and also exhibits the effect of promoting the solidification reaction when the additive [II] is added to the soil particle slurry to solidify it. . Generally, the amount of the auxiliary component added is preferably specified so as to be 0.01 to 4% by weight with respect to the water of the dredged mud. In the port dredging work, the resulting dredged mud contains seawater and contains about 3% by weight sodium chloride. Therefore, the fish reef of the present invention is advantageously manufactured by using the dredged mud obtained from the dredging work of the port.

Further, according to another method for preferably producing the artificial fishing reef according to the present invention, a flocculant is added to the dredged mud soil, and after the phase separation into the soil particle slurry phase forming the lower layer and the aqueous phase forming the upper layer, Manufacture of artificial fishing reef characterized by adding and mixing a solidifying agent consisting of gypsum, Portland cement and blast furnace slag to the obtained soil particle slurry, dehydrating the obtained mixture and solidifying it into a required shape. A method is provided.

As the coagulant used in this method, any coagulant capable of coagulating / precipitating soil particles suspended in water can be used, and conventionally known polymer coagulants and various inorganic coagulants can be used. However, in the case of the present invention, it is preferable to use an inorganic flocculant, and the use of gypsum is particularly advantageous. In this case, as described above, the gypsum has an effect of masking harmful substances such as organic substances such as humic acid and phosphates which adversely affect the hydration reaction of Portland semetone, in addition to the action as a flocculant, The solidifying agent works so as to work smoothly. Further, the amount of gypsum added in this case may be a slight amount capable of maintaining a state where the gypsum is saturated and dissolved. The amount is
It is the sum of the saturated dissolution amount of gypsum in water (seawater) and the cation exchange capacity of soil particle components. The saturated solubility of gypsum in water (seawater) is constant at 0.2% by weight, but the cation exchange capacity of soil particle components is determined by the type and amount ratio of clay minerals contained in soil particles and the type and amount of humus. Dominated by. However, the content of soil particles, which is usually handled, is 10
The weight% of dredged mud, the 1 m ³ per amount of gypsum is about 4kg in CaSO ₄ converted value (about 5kg as CaSO ₄ · 2H ₂ O)
Good.

In the above method, the dredged mud added with a flocculant is allowed to stand, and the suspended soil particles are allowed to settle to separate into a water phase forming an upper layer and a soil particle slurry phase forming a lower layer. . As the standing time elapses, the volume of the soil particle slurry phase decreases, and the soil particle concentration in the soil particle slurry phase gradually increases. In the present invention, the soil particle concentration in the soil particle slurry phase is at a suitable value, that is, at least 13% by weight, preferably at a time of 15 to 25% by weight,
The soil particle slurry after the water phase and the soil particle slurry phase are separated from each other is subjected to (i) further dehydration treatment, and gypsum, Portland cement and blast furnace slag are added and mixed therewith, or ( ii) Gypsum, Portland cement and blast furnace slag are added and mixed, and the resulting mixture is dehydrated and then solidified into the required shape. In this case, the dehydration treatment is generally 50 to 400 per 100 parts by weight of the soil particles, as described above.
In order to obtain a water content of parts by weight, for example, 100 to 400 parts by weight at the time of casting and 50 to 20 at the time of press molding.
Repeat until a water content of 0 parts by weight (the optimum value varies depending on the press pressure) is obtained.

The composition of the solidifying agent is as follows:
The total amount of Portland cement and blast furnace slag is 2 to 20 parts by weight, and the proportion of Portland cement is 40 to 55% by weight and the ratio of blast furnace slag to 60 to 50 parts by weight based on the total amount of Portland cement and blast furnace slag. 45% by weight. Gypsum, Portland cement, and blast furnace slag that constitute the solidifying agent can be added in the form of each of these three components alone, or any two of these components (Portland cement and blast furnace slag, gypsum and blast furnace). Water dregs or gypsum and Portland cement) can be added in the form of a mixture, and further in the form of a mixture of these three components.

The preferable amount of the solidifying agent is, as described above, (a)
Kind and pH value of dredged mud, (a) Content and quality of soil particles,
(D) Value of desired strength of solidified product, (e) Other, molding
Although the solidification method is different, the ratio of gypsum per 100 parts by weight of the soil particles contained in the soil particle slurry is at least 5 parts by weight. Specifically, it is in the range of 20 to 200 parts by weight per 100 parts by weight of soil particles.

In this method, when gypsum is used as the coagulant, 0.2% by weight is added to the separated / removed and dehydrated water layer.
It is only consumed including gypsum. Therefore, the amount of gypsum in the solidifying agent can be reduced accordingly.

The strength of the artificial fishing reef composed of a solidified product solidified by the solidifying agent for the dredged mud according to the present invention can be adjusted by the amount of the solidifying agent added.

In order to continuously and efficiently produce the artificial fishing reef according to the present invention, the first step of continuously adding and mixing the dredged mud and the gypsum or the flocculant to the mixer, supplying the obtained mixture to the thickener, Second step of continuously extracting clear water and soil particle slurry from the bottom, third step of continuously dehydrating the obtained soil particle slurry, and fourth step of adding and mixing a solidifying agent to the prepared dehydrated product , And the fifth step of molding and solidifying the prepared mixture thus obtained in a required mold is preferably combined.

The artificial reef of the present invention is advantageously manufactured using the dredged mud obtained in the port dredging work. In this case, the artificial reef can be manufactured on board.

The solidified material of the dredged mud according to the present invention exhibits excellent performance as an artificial fishing reef. That is, since this solidified product usually contains 5% by weight or more of an organic substance, it provides an environment suitable for breeding algae and seafood.

〔effect〕

According to the present invention, by using the dredged mud soil, which has been considered to be difficult to handle until now, as an artificial fishing reef material,
It is possible to solve the problem of treating dredged mud, and the solidified product obtained by treating this dredged mud has excellent fishing reef performance and is not obtained with conventional concrete blocks that are cheap. Have advantages.

〔Example〕

 Next, the present invention will be described in more detail with reference to Examples.

Example 1 As the dredged mud, one having the following properties obtained from the seabed dredging work was used.

Next, 1 m ³ of the dredged mud was placed in a container, and 19.5 kg of the additive [I] (dihydrate gypsum) was added thereto, and the mixture was uniformly mixed and then allowed to stand. By this standing, the suspended particles aggregate to form a sedimentary phase (soil particle slurry phase) containing soil particles in the container as a lower layer, and a water (seawater) phase as an upper layer. In this case, with the lapse of time, the soil particle slurry phase gradually drops, the volume of the soil particle slurry phase decreases, and the volume of the water layer increases accordingly. Three hours after the start of the experiment, the volume ratio of the water phase to the soil particle slurry phase was 40/60.

Next, the soil particle slurry phase is separated, and this is
It was dehydrated by a centrifugal dehydrator so that the amount of seawater was 200 parts by weight with respect to 100 parts by weight. Gypsum was saturated and dissolved in the water layer discharged from the centrifugal dehydrator, and the dissolved amount was 2 g of CaSO ₄ per seawater (2.5 g of CaSO ₄ .2H ₂ O). To the soil particle slurry extracted from this centrifugal dehydrator,
71 kg of an additive [II] [a mixture of 50% by weight of Portland cement and 50% by weight of fine blast furnace slag (average particle size 6 μm)] was mixed. Next, a portion of this mixture is 5 cm in diameter and 10 c high.
It is filled in a cylindrical m-shaped mold of m, wrapped with polyvinylidene chloride film so that water does not evaporate, and stored at room temperature (15 ~
After curing for 28 days at 20 ° C), the mold was removed. The uniaxial compressive strength of this molded product was 46.8 kgf / cm ² (JIS A 1216T 1979).
Method). Further, the rest of the mixture was similarly shaped into a semi-cylindrical shape having a length of 31 cm and a radius of 7 cm to form an artificial fishing reef.

Next, 10 artificial fishing reefs obtained from the submarine dredged mud obtained above were placed on the seabed (location: Izumi Port, Atsumi Town, Atsumi County, Aichi Prefecture, depth: 3 m).
I put it in. For comparison, 10 concrete reefs with the same shape were also added. One month after the input, they were taken out from the seabed and the type and amount of the organisms that propagated on the surface of the reef were visually determined. As a result, a larger amount of organisms are attached to the reef according to the present invention,
It was confirmed that they were breeding. The following table shows the test results.

Example 2 1 m ³ of the dredged mud shown in Example 1 was placed in a container and 2
After adding and mixing 5 kg of water gypsum and allowing it to stand for 3 hours, the resulting aqueous phase (volume ratio of about 40%) was separated and removed. The soil particle slurry obtained by separating and removing this aqueous phase is further subjected to a dehydrator to give 400, 350, 300, 250 and 2 per 100 parts by weight of the soil particle content.
A dehydrated product containing 00 parts by weight of seawater was prepared. The amount of seawater discharged / removed was adjusted by measuring the amount of discharged / removed seawater (the separated / removed aqueous phase and the total amount of seawater discharged from the dehydrator).

Next, 350g, 300g and 250g of solidifying agent are added and mixed to each 1 adjusted to this predetermined amount of seawater, and 1 day of 28th
The axial compressive strength was measured under the same operating conditions as in Example 1. The results are shown in the table below. The solidifying agent used in this example was composed of 20 parts by weight of gypsum dihydrate, 40 parts by weight of fine blast furnace slag and 40 parts by weight of Portland cement.

The following table shows the uniaxial compressive strength of the obtained solidified material on the 28th day.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuo Mahinagi 2-2-14 Chuo, Kashiwa City, Chiba Prefecture (56) References JP 48-67080 (JP, A) JP 55-49200 (JP, A) ) Japanese Patent Laid-Open No. 59-145100 (JP, A) Actually developed 55-77958 (JP, U)

Claims (4)

[Claims] 1. The following treatment agent (A) or (B) on dredged mud
Add the additive [I] of to condense the colloidal content in the mud.
After coagulation, dehydration treatment is performed to form a soil particle slurry containing at least 5 parts by weight of gypsum and 50 to 400 parts by weight of water per 100 parts by weight of the soil particles. An additive [II] of the treating agent A is added and mixed at a ratio of 2 to 20 parts by weight per 1 part by weight of gypsum contained in the soil particle slurry to obtain a soil particle slurry containing the treating agent A, or (ii) The ratio of the additive [II] of the treating agent B to the total amount of the fine blast furnace water slag contained in the soil particle slurry and the additive [II] is 40 to 55% by weight. A method for producing an artificial fishing reef, which comprises adding and mixing as described above to obtain a soil particle slurry containing the treating agent B, and then solidifying the soil particle slurry into a required shape. Treatment agent (A) Additive [I]: Gypsum Additive [II]: Portland cement 40-55% by weight and fine blast furnace water slag 60-45% by weight Treatment agent (B) Additive [I]: Gypsum And fine blast furnace slag, Ca
Mixture with SO ₄ content of 10 to 50 wt% Additive [II]: Portland cement 2. The following processing agent A or B additive [I] is added to the dredged mud, and the mixture is allowed to stand and soil particles 10 contained in the mud are added.
After phase separation into a lower layer consisting of a soil particle slurry phase containing at least 5 parts by weight of gypsum per 0 parts by weight and an upper layer consisting of an aqueous phase, the obtained soil particle slurry is subjected to (i) dehydration treatment A soil particle slurry having a ratio of water per 100 parts by weight of particles of 50 to 400 parts by weight is prepared, and an additive [II] of the following treating agent A is added to this per 2 parts by weight of soil particles contained in the slurry of soil particles. ˜20 parts by weight to add and mix to obtain a soil particle slurry containing the treating agent A, or (ii) an additive [II] of the following treating agent B is added to the fine blast furnace water slag contained in the soil particle slurry. And the additive [II] is added and mixed so that the ratio of the additive [II] to the total amount of the additive [II] is 40 to 55%, and the mixture is dehydrated to obtain soil particles 10
A method for producing artificial reef, characterized by obtaining a soil particle slurry containing 50 to 400 parts by weight of water per 0 parts by weight of the treating agent B, and then solidifying the soil particle slurry into a required shape. . Treatment agent (A) Additive [I]: Gypsum Additive [II]: Portland cement 40-55% by weight and fine blast furnace water slag 60-45% by weight Treatment agent (B) Additive [I]: Gypsum And fine blast furnace slag, Ca
Mixture with SO ₄ content of 10 to 50 wt% Additive [II]: Portland cement 3. A flocculant is added to the dredged mud soil, and the mixture is allowed to stand to cause phase separation into a lower layer composed of a soil particle slurry phase and an upper layer composed of an aqueous phase, and then the resulting soil particle slurry is provided with (i ) Dehydrated to make a soil particle slurry with 50 to 400 parts by weight of water per 100 parts by weight of soil particles. This soil particle slurry consists of gypsum, Portland cement and fine blast furnace water slag, and 1 part by weight of gypsum The total amount of Portland cement and blast furnace slag per part is 2 to 20 parts by weight, and the ratio of Portland cement to the total amount of Portland cement and blast furnace slag is 40 to 55% by weight and the ratio of blast furnace slag is Soil particles containing a solidifying agent by adding and mixing 60 to 45% by weight of the solidifying agent so that the amount of gypsum added is at least 5 parts by weight per 100 parts by weight of the soil particles in the soil particle slurry. Obtain a slurry, or (ii ) It consists of gypsum, Portland cement and fine blast furnace water slag, and the total amount of Portland cement and blast furnace slag is 2 to 20 parts by weight per 1 part by weight of gypsum. 40-55% by weight and 60% by weight of blast furnace slag
~ 45 wt% solidifying agent is added and mixed so that the amount of gypsum added is at least 5 parts by weight per 100 parts by weight of the soil particles in the soil particle slurry. Dehydration treatment is performed to obtain a soil particle slurry containing a solidifying agent having a water content of 50 to 400 parts by weight per 100 parts by weight of the soil particles, and then the soil particles containing the solidifying agent thus obtained. A method for producing an artificial fishing reef, which comprises solidifying a slurry into a required shape. 4. The third aspect of the present invention, wherein the coagulant is gypsum.
Method of terms.