JPH07246397A - Treatment of dredging slurry - Google Patents

Abstract

PURPOSE:To effectively reduce the water content per volume of a dredging slurry having a high content of water with a highly water-absorptive fly ash having a low sp.gr. and to efficiently agglomerate the slurry with the inexpensive and easily available fly ash at a low cost without using an expensive additive. CONSTITUTION:Fly ash and cement and/or quick lime are added to a dredging slurry contg. >=100wt.% water with respect to the solid. A pulverized coal ash is added to the slurry, and then a water-soluble polymer absorbent is added. Alternatively, the water-soluble polymer absorbent is added, then a fluidized-bed boiler ash is added, and then cement and/or quick line are added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a dredging slurry, and particularly to agglomerating a high water content dredging slurry having a water content of 100% by weight or more with respect to solid content at low cost and efficiently. Regarding how to handle.

[0002]

2. Description of the Related Art A large amount of dredging slurry is generated in a dredging work, but the dredging slurry thus generated needs to be solidified to some extent, whether it is discarded or backfilled.

By the way, conventionally, the industrial waste soil and construction waste soil of clay-based slurry are solidified according to their water content (in this specification, the water content means the ratio of the weight of water to the weight of solid content). In contrast, water content of 40% or less and a relatively low water content are subjected to water adjustment by adding quick lime (CaO) and solidification treatment by a pozzolan reaction. Further, those having a water content of 40 to 100% have been solidified by adding cement, or cement and a polymer absorbent and / or quick lime.

However, in the high water content slurry having a water content of 100% or more, it is necessary to add a large amount of the solidifying material in the above-mentioned method, and the treatment cost rises.
The present situation is that after sun-drying for a long period of time to reduce the water content, post-treatment is performed.

The dredging slurry generated in the dredging work is also
Since it is a high water content slurry having a water content of 100% or more, solidification requires long-term sun drying.

[0006]

As described above, since the dredging slurry has a high water content, the solidification treatment of the dredging slurry has the following problems.

That is, in order to prevent an increase in the amount of the solidifying material such as quick lime used and to avoid a cost increase, it is necessary to dry in the sun for a long time. In this case, the period required for the treatment becomes long. There are problems such as the need to secure space for sun drying.

On the other hand, if it is attempted to improve the treatment efficiency without performing the sun drying, it is necessary to add a large amount of the solidifying material, which causes a rise in the treatment cost.

An object of the present invention is to solve the above conventional problems and to provide a method for efficiently solidifying a dredged slurry having a high water content of 100% or more at a low cost.

[0010]

A method of treating a dredged slurry according to claim 1 is a method of agglomerating a dredged slurry having a water content of 100% by weight or more based on a solid content, wherein fly ash is applied to the dredged slurry. And cement and / or quick lime are added.

According to a second aspect of the present invention, there is provided a method for treating a dredging slurry, wherein the dredging slurry having a water content of 100% by weight or more with respect to a solid content is subjected to an agglomeration treatment. Material and cement and / or quick lime are added, characterized in that the water-soluble polymer absorbent is added to the dredging slurry, then the water-soluble polymer absorbent is added, and then the cement and / or lime is added. And

According to a third aspect of the present invention, there is provided a method for treating a dredging slurry, wherein the dredging slurry having a water content of 100% by weight or more relative to a solid content is subjected to agglomeration treatment. A method of adding an absorbent and cement and / or quick lime, which comprises adding a water-soluble polymer absorbent to the dredging slurry, then adding fluidized bed boiler ash, and then adding cement and / or lime. Is characterized by.

According to a fourth aspect of the present invention, in the method for treating a dredging slurry, the fluidized bed boiler ash and the water-soluble polymer are added to the dredging slurry when the dredging slurry having a water content of 100% by weight or more relative to the solid content is aggregated. A method of adding an absorbent and cement and / or quicklime, which comprises adding a water-soluble polymer absorbent to a dredging slurry being pumped and then mixing with a mixer, and then fluidized bed boiler ash and cement and / or It is characterized by adding and mixing quick lime.

That is, cement and / or quick lime is effective for solidifying the dredging slurry, but it is necessary to add a large amount to a high water content slurry, which causes a cost increase.

The present inventor has studied the reduction of the amount of cement and / or quick lime added to the high water content dredging slurry, and as a result, by adding fly ash to the dredging slurry to reduce the water content per volume, the cement It was found that the amount of quicklime added can be reduced and the present invention has been completed.

The present invention will be described in detail below.

In the method of claim 1, the water content is 100.
Fly ash and cement and / or quick lime are added to the high water content dredging slurry above%.

In the method of claim 1, the fly ash is preferably added so that the water content of the dredging slurry after the addition and mixing of the fly ash is 100% or less, preferably about 100 to 40%. Is appropriately determined according to the water content of the dredging slurry to be treated, generally, when adding fly ash and cement or quick lime to the dredging slurry, 160 to 20% by weight of fly ash to the dredging slurry, 40% by weight of cement
It is preferable to add 26 to 10% by weight or 40% by weight or less of quicklime, particularly 26 to 10% by weight. When both cement and quick lime are added, the cement is added to the dredging slurry in an amount of 32% by weight or less, particularly 16 to 5% by weight, quicklime is 32% by weight or less, particularly 16 to 5% by weight, and the total amount of cement and quicklime is It is preferable that the addition amount of the above is 40% by weight or less, particularly 26 to 10% by weight based on the dredging slurry.

In the method of claim 1, fine coal ash, fluidized bed boiler ash, or the like can be used as the fly ash. In particular, in the case of fluidized bed boiler ash, the CaO and CaSO ₄ contained in the ash can be used for more efficient solidification treatment.

These fly ashes are produced in large amounts in various places as industrial waste and can be obtained at low cost.

The general composition of pulverized coal ash and fluidized bed boiler is as follows.

[0022]

[Table 1]

In the method of claim 1, the order of addition of fly ash and cement and / or quick lime is not particularly limited, and they may be added at the same time, or one of them may be added first. .

In the method of claim 2, finely ground carbon ash as fly ash is added to and mixed with the dredging slurry, then a water-soluble polymer absorbent is added and mixed, and then cement and / or
Alternatively, quick lime is added and mixed.

In this case, the fine coal ash is 160 to 20% by weight with respect to the dredging slurry, and the water-soluble polymer absorbent is 3% by weight.
Hereafter, it is particularly preferable to add 0.3 to 0.1% by weight. When cement or quick lime is added, it is preferable to add 15% by weight or less of cement, particularly 8 to 4% by weight, or 15% by weight or less of quicklime, particularly 8 to 4% by weight. When both cement and quicklime are added, the amount of cement is 13% by weight or less based on the dredging slurry, especially 5%.
~ 1.5 wt%, quicklime 13 wt% or less, especially 5 ~
1.5% by weight, and the total amount of cement and quicklime added is 15% by weight or less based on the dredging slurry, especially 8 to 3.5.
It is preferable to set it to be the weight%.

In the method of claim 3, after the water-soluble polymer absorbent is added and mixed to the dredging slurry, fluidized bed boiler ash is added and mixed, and then cement and / or quick lime is added and mixed.

In this case, it is preferable to add 160 to 20% by weight of the fluidized-bed boiler ash to the dredging slurry, and 3% by weight or less, especially 0.3 to 0.1% by weight of the water-soluble polymer absorbent. When cement or quick lime is added, it is preferable to add 15% by weight or less of cement, particularly 8 to 4% by weight, or 15% by weight or less of quicklime, particularly 8 to 4% by weight. When both cement and quicklime are added, the cement is added in an amount of 13% by weight or less based on the dredging slurry,
In particular, 5 to 1.5% by weight, quick lime 13% by weight or less, particularly 5 to 1.5% by weight, the total addition amount of cement and quicklime is 15% by weight or less, especially 8 to 8% with respect to the dredging slurry.
It is preferably set to 3.5% by weight.

In the method of claim 4, a water-soluble polymer absorbent is added to the dredging slurry being pumped and mixed by a static mixer, and then fluidized bed boiler ash and cement and / or quick lime are mixed. Are added and mixed, preferably in a paddle mixer.

In this case, the ratio of addition of each additive is the same as that of claim 3.

The static mixer is a low viscosity type, and premixing is performed by mixing with this mixer. On the other hand, the paddle mixer is for high viscosity, and sufficient kneading is achieved by mixing with this mixer.

In the method according to any one of claims 1 to 4, when the amount of fly ash added to the dredging slurry is less than the above range, the required amount of the water-soluble polymer absorbent, cement and quick lime added is reduced by adding fly ash. If the effect is not sufficiently obtained and the amount is large, it may be difficult to aggregate into a predetermined strength. If the proportion of cement and / or quick lime is less than the above range, it cannot be sufficiently solidified, and if it is high, the cost of adding cement and / or quick lime is high, which is not preferable.

The water-soluble polymer absorbent is added in order to accelerate the solidification of the dredging slurry by absorbing the water in the dredging slurry and gelling it, thereby reducing the amount of cement and / or quick lime added. However, if it is less than the above range, the effect of reducing the amount of cement and / or quick lime added cannot be sufficiently obtained, and if it is more than the above range, the cost rises undesirably.

The addition ratio of each additive is appropriately determined in the above range depending on the degree of water content of the dredging slurry and the treatment method after agglomeration (whether to discard or reuse for landfill). It is preferable to determine.

[0034]

[Function] Fly ash such as pulverized coal ash and fluidized bed boiler ash has a low specific gravity and high water absorption, and can effectively reduce the water content per volume of the high water content dredging slurry.

In particular, the fluidized bed boiler ash is effective in adjusting the water content and solidifying by the pozzolan reaction because it contains a large amount of CaO, and because it contains CaSO ₄ , it is effective in expressing the aggregation strength by the formation of ettringite.

By adding these fly ash, the water content of the dredging slurry is reduced, and by adding an appropriate amount of cement and / or quick lime, or a water-soluble polymer absorbent and cement and / or quick lime, It becomes possible to form aggregates with high strength.

According to the method of claim 2, by adding the fine coal powder ash to the dredging slurry in advance, the necessary addition amount of the water-soluble polymer absorbent and the cement and It is possible to perform an efficient treatment by significantly reducing the required amount of quicklime added.

According to the method of claim 3, the water-soluble polymer absorbent is added to the dredging slurry to reduce the water content, and then the fluidized-bed boiler ash is added, whereby the above-mentioned aggregates by the fluidized-bed boiler ash are added. The effect of manifesting chemical strength can be sufficiently exerted, and as a result, the required addition amount of the water-soluble polymer absorbent and the required addition amount of cement and / or quick lime can be significantly reduced, and efficient treatment can be performed. .

According to the method of claim 4, the water-soluble polymer absorbent is added to the dredging slurry being pumped and mixed to effectively and uniformly mix the water-soluble polymer absorbent with the dredging slurry. Further, by adding and mixing the fluidized bed boiler ash with cement and / or quick lime thereafter, efficient treatment can be performed with a small amount of the water-soluble polymer absorbent, cement and / or quick lime added.

[0040]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

The composition of the fly ash used in the following is as shown in Table 2.

[0042]

[Table 2]

Examples 1 to 7 and Comparative Examples 1 and 2 Each additive was added and mixed at a ratio shown in Table 3 to a high water content dredging slurry having a water content of 154%, and it was examined whether or not agglomeration was possible. Shown in 3. The aggregated strength was shown by relative evaluation with reference to the one obtained in Comparative Example 1. As is clear from Table 1, the addition of fly ash enables agglomeration to be performed with a small amount of cement and / or quick lime added.

On the other hand, in Comparative Example 1 in which fly ash was not used, a large amount of cement was required for agglomeration, and in comparison with Example 1, the amount of cement added was the same as in Example 1 without using fly ash. In Example 2, the aggregate could not be formed.

[0045]

[Table 3]

Examples 8 to 10, Comparative Examples 3 and 4 Each additive was added and mixed at a ratio shown in Table 4 to a high water content dredging slurry having a water content of 154%, and it was examined whether or not agglomeration was performed. Shown in FIG. In addition, in Examples 8 to 10, after adding the fine carbon ash, the water-soluble polymer absorbent was added, and then the cement and / or quick lime was added. Further, the aggregated strength was shown by relative evaluation with reference to the one obtained in Comparative Example 3.

Comparative Example 5 Treatment was carried out in exactly the same manner as in Example 8 except that the water-soluble polymer absorbent was added to the dredging slurry, then the fine carbonaceous ash was added, and then cement and / or quick lime was added.
The presence or absence of agglomeration and the agglomeration strength were examined, and the results are shown in Table 4.

As is clear from Table 4, by adding the finely divided carbon ash before the addition of the water-soluble polymer absorbent, it is possible to efficiently add a small amount of the water-soluble polymer absorbent, cement and / or quick lime. It is understood that the aggregate treatment can be performed.

On the other hand, in Comparative Example 3 in which pulverized coal ash is not used, a large amount of water-soluble polymer absorbent or cement is required for agglomeration. Further, in Comparative Example 4 in which the fine water-based carbon ash was not used and the water-soluble polymer absorbent and the amount of cement added were similar to those in Example 8, it was impossible to aggregate. Furthermore, Comparative Example 5 in which a water-soluble polymer absorbent was added before the addition of pulverized coal ash
Then, the aggregated strength was inferior.

[0050]

[Table 4]

Examples 11 to 13 and Comparative Examples 6 and 7 Each additive was added and mixed at a ratio shown in Table 5 to a high water content dredging slurry having a water content of 154%, and it was examined whether or not aggregated. 5 shows. In addition, in Examples 11 to 13,
After adding the water-soluble polymeric absorbent, fluidized bed boiler ash was added, followed by cement and / or quicklime. In addition, the aggregated strength was shown by relative evaluation with reference to that obtained in Comparative Example 6.

Comparative Example 8 Treatment was carried out in the same manner as in Example 11 except that the fluidized bed boiler ash was added to the dredging slurry, then the water-soluble polymer absorbent was added, and then cement and / or quick lime was added. The presence or absence of agglomeration and the agglomeration strength were examined, and the results are shown in Table 5.

As is clear from Table 5, by adding the fluidized bed boiler ash after the addition of the water-soluble polymer absorbent, it is possible to efficiently add a small amount of the water-soluble polymer absorbent, cement and / or quick lime. It is understood that the aggregate treatment can be performed.

On the other hand, in Comparative Example 6 in which the fluidized bed boiler ash is not used, a large amount of water-soluble polymer absorbent or cement is required for agglomeration. Further, in Comparative Example 7 in which the fluidized bed boiler ash was not used and the water-soluble polymer absorbent and the amount of cement were the same as in Example 11, it was impossible to aggregate. Furthermore, in Comparative Example 8 in which the water-soluble polymer absorbent was added after the addition of the fluidized bed boiler ash, the aggregate strength was poor.

[0055]

[Table 5]

Examples 14 to 16 Aggregation treatment of dredging slurry was performed according to the method shown in FIG.

In the method shown in FIG. 1, the slurry 1 such as mud sludge on the bottom of the water is dredged by the dredger 3 of the dredger 2. The dredger 3 is composed of a screw conveyor and takes in the slurry from the lower end and discharges the slurry from the upper part. The slurry is introduced from the dredger 3 into the slurry pump 4 and then fed into the first mixer M ₁ . During this process, the water-soluble polymer absorbent is added by the addition device 5 and introduced into the static first mixer M ₁ . The slurry kneaded by the first mixer M ₁ is introduced into a paddle mixer M ₂ which is a second mixer, and kneading is performed while adding fluidized bed boiler ash, cement and / or quick lime by adding devices 6 and 7, respectively. To be done. This kneaded material is a non-greasy clay-like material, and the second mixer M
_{From 2} to the carrier 8 via the conveyor 8. When the carrier 9 is full, the carrier 9 is replaced with another carrier, and the carrier 9 that is full transports the soil to land or another dumping place.

When the addition ratio of each additive was set as shown in Table 6, good aggregated soil could be obtained in all cases.

[0059]

[Table 6]

In this embodiment, the fluidized bed boiler ash is added by the addition device 5, the water-soluble polymer absorbent is added by the addition device 6, and the cement and / or quick lime is added by the addition device 7. Applying the illustrated method to the method of claim 2,
It is also possible to add pulverized coal ash with the addition device 5 and add the water-soluble polymer absorbent, cement and / or quick lime with the addition devices 6 and 7.

Instead of using the addition device 6, fly ash may be added by the addition device 5 and cement and / or quick lime may be added by the addition device 7.

[0062]

As described above in detail, according to the method for treating a dredging slurry of the present invention, a high water content dredging slurry having a water content of 100% or more is used by using fly ash which is easily available at low cost. It is possible to efficiently perform the agglomeration treatment at low cost without adding a large amount of expensive additive material.

That is, according to the method of claim 1, the amount of cement and / or quick lime used can be reduced.

According to the methods of claims 2 and 3, the amount of water-soluble polymer absorbent used, the amount of cement and / or quick lime used can be reduced, and an aggregate having a relatively high agglomeration strength can be obtained. it can.

According to the method of claim 4, each additive can be efficiently added to the dredging slurry being fed under pressure, and a good treatment can be carried out.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example method of a method for treating a dredging slurry of the present invention.

[Explanation of symbols]

1 Slurry 2 Dredger 3 Dredger 4 Slurry pump 5,6,7 Addition device 8 Conveyor 9 Carrier Vessel M ₁ 1st mixer M ₂ 2nd mixer

Claims (4)

[Claims] 1. A method for aggregating a dredging slurry having a water content of 100% by weight or more with respect to solid content, wherein fly ash, cement and / or quick lime are added to the dredging slurry. Treatment method of dredging slurry. 2. When the dredging slurry having a water content with respect to the solid content of 100% by weight or more is subjected to the agglomeration treatment, the dredging slurry contains pulverized carbon ash, a water-soluble polymer absorbent, cement and / or quick lime. The method for treating a dredging slurry, which comprises adding pulverized carbon ash to the dredging slurry, then adding a water-soluble polymer absorbent, and then adding cement and / or lime. 3. A fluidized bed boiler ash, a water-soluble polymer absorbent, cement and / or quick lime are added to the dredging slurry when the agglomeration treatment is performed on the dredging slurry having a water content of 100% by weight or more based on the solid content. And a method of adding a water-soluble polymer absorbent to the dredging slurry, and then adding fluidized-bed boiler ash, and then adding cement and / or lime to the dredging slurry. . 4. A fluidized-bed boiler ash, a water-soluble polymer absorbent, cement and / or quick lime are added to the dredging slurry for the agglomeration treatment of the dredging slurry having a water content of 100% by weight or more based on the solid content. And a method of adding a water-soluble polymer absorbent to a dredging slurry being pumped, followed by mixing with a mixer, and then adding and mixing fluidized bed boiler ash and cement and / or quick lime. And method for treating dredging slurry.