KR20040012415A - Recycle method of construction sludge and granulator used in the method - Google Patents

Abstract

PURPOSE: To provide a method of producing regenerated sand from construction sludge by which good quality regenerated sand is efficiently and economically produced using construction sludge discharged with an excavation work concerned with a construction work as a raw material. CONSTITUTION: The method of producing the regenerated sand from the construction sludge is a method of recovering a granulated material having a particle size equal to or below a prescribed size as the regenerated sand. The granulated material is obtained by using dehydrated cake obtained by dehydrating the construction sludge and cement as raw materials, adding water and kneading to granulate it and after aging the resultant granulated material, classifying. The quantity of the cement to be blended is controlled to >=5 wt.% to <20 wt.% per the whole raw material.

Description

Recycling method of construction sludge and granulator used for the method {RECYCLE METHOD OF CONSTRUCTION SLUDGE AND GRANULATOR USED IN THE METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recycling method for a construction sludge, which can easily and economically obtain high quality recycled sand from a construction sludge, and to a granulator used in the method.

Construction sludge, which consists of fine particles containing a large amount of moisture, discharged by excavation work due to construction work, is treated as industrial waste, and conventionally discharged construction sludge is landfilled after dehydration to lower the water content. .

However, securing landfills has become increasingly difficult year after year, and in particular, in the metropolitan area where the amount of construction sludge is high, landfills cannot be secured, and construction sludge must be transported to a distant treatment plant, causing a rise in treatment cost.

On the other hand, sand, which is a raw material for concrete aggregates, has been collected from rivers in the past, but as a result of continued collection in large quantities over a long period of time, the resources of river sand are depleted.

Because of this situation, many attempts have been made to recycle construction sludge as a recyclable resource or to obtain reclaimed sand from construction waste materials, but it is an effective method for obtaining high quality recycled sand from construction sludge. The device applied to is not yet proposed.

The present invention has been made in view of the above circumstances, and a recycling method for a construction sludge and a granulator used in the method, which can obtain a high quality recycled sand at a low cost from a large amount of construction sludge generated with the excavation work according to the construction work. It aims to provide.

1 is a flowchart showing Embodiment 1 of a recycling method of construction sludge according to the present invention.

2 is a flowchart showing Embodiment 2 of a recycling method of construction sludge according to the present invention.

3 is a flowchart showing Embodiment 3 of a recycling method of construction sludge according to the present invention.

4 is a front view showing an example of a granulator used in the method according to the present invention.

FIG. 5 is a plan view showing the interior of a treatment tank in the granulator of FIG.

6 is a plan view schematically showing the structure of a treatment tank in an example of a granulator used in the method according to the present invention.

7 is a front view schematically showing the structure of a treatment tank in one example of a granulator used in the method according to the present invention.

8 is a view showing a particle size curve of a first assembly and a second assembly obtained in the invention according to the present invention, and a construction sludge (dehydrated cake) as a raw material.

<Explanation of symbols for the main parts of the drawings>

1: granulator (first granulator), 2: treatment tank,

3: rotation axis, 6: crushing wing,

7: rake wings, 8: treatment tank,

9: screen, 10: axis of rotation,

11: stirring blade

The present invention is to solve the above object, in the invention according to claim 1, the dehydration cake and cement obtained by dehydrating the construction sludge as a raw material, the blending amount of the cement is 5% to 20% by weight of the whole raw material These are supplied together with water to a granulator to assemble, the obtained granulated product is cured for a certain period of time, then dried, and the granulated product after drying is classified to assemble at a predetermined particle size or less. It was set as the recycling method of the construction sludge which collect | recovers water as recycled sand.

In the invention according to claim 2, the dewatering cake obtained by dehydrating the construction sludge and cement are used as raw materials, and the blending amount of the cement is 5% by weight or more and less than 20% by weight of the whole raw material, and these are kneaded together with water ( After supplying to the machine, it is fed to the granulator, and then granulated. The obtained granulated product is cured for a certain period of time, then dried, the dried granulated material is classified, and the granulated material having a predetermined particle size is recovered as reclaimed sand. It was made into the recycling method of the construction sludge characterized by the above-mentioned.

In the invention according to claim 3, the dewatering cake obtained by dehydrating the construction sludge and cement are used as raw materials, and the blending amount of the cement is 5% by weight or more and less than 20% by weight of the whole raw material, and these are supplied to the first granulator together with water. The first assembly obtained by assembling and the dewatering cake and cement obtained by dehydrating the construction sludge as raw materials, and the second assembly obtained by supplying these to the kneader with water to be kneaded and then feeding the granulator to the second granulator. The granulated product obtained by mixing was dried after curing for a certain period of time, and the granulated product after drying was classified, and granulated materials having a predetermined particle size or less were recovered as recycled sand.

In the invention according to claim 4, slag is added as the raw material according to any one of claims 1 to 3, so as to recycle the construction sludge.

In the invention according to claim 5, incineration ash is added as the raw material according to any one of claims 1 to 3, wherein the recycle sludge of the construction sludge is used.

In the invention according to claim 6, gypsum is added as the raw material according to any one of claims 1 to 3, and it is set as the recycling method of construction sludge.

In the invention according to claim 7, the curing method according to any one of claims 1 to 3, wherein the curing is carried out in water.

In the invention according to claim 8, according to claim 4, said curing is performed in water, and it was set as the recycling method of the construction sludge.

In the invention according to claim 9, according to claim 5, the curing is carried out in water.

In the invention according to claim 10, according to claim 6, the curing is carried out in the water, it was set as a recycling method of construction sludge.

In the invention according to claim 11, the curing method according to any one of claims 1 to 3, wherein the curing is performed by sun drying.

In the invention according to claim 12, according to claim 4, the curing method is a recycling method of construction sludge, characterized in that the drying is performed by sun drying.

In the invention according to claim 13, according to claim 5, the curing method is a recycling method for construction sludge, characterized in that the drying is performed by sun drying.

In the invention according to claim 14, the recycling method for construction sludge according to claim 6, wherein the curing is performed by sun drying.

In the invention according to claim 15, the recycling sludge of the construction sludge according to claim 11 is characterized in that water is supplied to the granulated product during the curing period by sun drying.

In the invention according to claim 16, the recycling method for construction sludge according to claim 12, wherein water is supplied to the granulated product during the curing period by sun drying.

In the invention according to claim 17, the recycling sludge of construction sludge according to claim 13 is characterized in that water is supplied to the granulated product during the curing period by sun drying.

In the invention according to claim 18, the recycling sludge of the construction sludge according to claim 14 is characterized in that water is supplied to the granulated product during the curing period by sun drying.

A granulator for assembling a dewatering cake and cement obtained by dehydrating a construction sludge as a raw material, comprising: a treatment tank having a screen on a circumferential wall; While stirring the raw materials introduced into the treatment tank, the granulator having a predetermined particle size or less is provided with a stirring blade for extruding from the screen to the outside.

EMBODIMENT OF THE INVENTION Hereinafter, the recycling method of the construction sludge which concerns on this invention, and the suitable Example of the granulator used for the method are demonstrated, referring drawings.

1 is a flowchart showing Embodiment 1 of a recycling method of construction sludge according to the present invention.

The kind of construction sludge which is a raw material in the present invention is not particularly limited, and the two-phase sludge and the earth pressure shielding method, which are discharged by a distillation shield method, a continuous underground wall method, an earth drill method, or the like. Either the soil sludge discharged by the earth drill method, the magnetic sludge discharged by the high pressure spray stirring method, the soil cement wall method, etc. can be used.

These construction sludges are first dehydrated to be dehydrated cakes.

In the dehydration treatment, an apparatus used for a conventional sludge dewatering treatment can be used. For example, a vacuum filter, a pressure filter, a gravity filter, or the like can be used.

In addition, in the case of Ito sludge which is difficult to dehydrate mechanically, you may make it into a dehydration cake by sun drying.

In this dehydration treatment, when unnecessary substances such as gravel are mixed in the sludge, the gravel is removed by a classifier.

The above process is a structure common in this invention.

Next, cement and water are added and kneaded to the dewatered cake obtained by dehydration treatment.

At this time, incineration ash and / or slag may be further added in addition to cement and water as components to be kneaded with the dehydrated cake. Only incineration ash may be added to this incineration ash and slag, only slag may be added, and both incineration ash and slag may be added.

In this way, when incineration ash and / or slag is added to the raw material, the amount of cement used can be reduced, and at the same time, the waste incineration ash and slag can be effectively recycled.

The incineration circuit is preferably baked at a temperature of 1,000 to 1,100 ° C by a rotary kiln or the like from the incinerator, and a chelating agent added thereto is preferably used.

This is because the dioxin contained in the incineration ash can be decomposed by baking the incineration ash from the incinerator at a temperature of 1,000 to 1,100 ° C, and the heavy metals can be removed by adding a chelating agent.

Alternatively, gypsum may be added instead of incineration ash and / or slag.

As the gypsum to be added, for example, gypsum taken out of the gypsum board discharged as construction waste material is used.

Assembly by granulator is carried out by adding dehydrated cake, cement and water to the granulator, and incineration ash, slag, and gypsum as necessary.Injection of each material into the granulator is first carried out by putting the dehydrated cake into the granulator. The weight is measured, and when the input weight reaches the set value, it is automatically controlled to add a predetermined cement and water and at least one additive selected from incineration ash, slag and gypsum as necessary.

Although the granulator used is not specifically limited, For example, a screen feeder or a tornado pin type granulator can be used.

The kneading treatment by this granulator is performed, for example, for about 3 to 6 minutes, and as a result, the introduced sludge increases its particle diameter and is sequentially taken out by the belt conveyor as a granular product (assembly product).

The product obtained by kneading by a granulator is cured for a certain period of time.

In the present invention, the curing may be performed by wet treatment in water or by dry treatment in air.

In the case of curing in water, the curing period takes about one week, during which the cement absorbs water and the strength of the product is improved. Then, the product cured for a certain period of time is then sun-dried over about a day, the moisture content is low.

In the case of curing in the air, the curing period takes 15 to 20 days. Such dry curing is effective in places where it is difficult to obtain a large amount of water.

In this invention, the compounding quantity of the cement occupied by the whole raw material (dehydration cake + cement + additive) is set to 5 weight% or more and less than 20 weight%, More preferably, it is 5 weight% or more and less than 13 weight%. This is also a common configuration in the present invention.

In the wet or dry curing process described above, if the amount of cement is less than 5% by weight, the amount of cement is too small, so that the granulated product is not sufficiently solidified. This is because the crushing process must be carried out in order to obtain a. When the blending amount of cement is in the range of 5% by weight or more and less than 20% by weight, it is possible to efficiently recover a small-diameter product that can be used as reclaimed sand without requiring a shredding process because the granulated material is spontaneously divided during curing. have. And such an effect is reliably obtained by making the compounding quantity of cement into the range which is 5 weight% or more and less than 13 weight%.

In the case of aquatic curing, it is spontaneously divided during curing. In the case of dry curing, it is usually divided on the basis of the absorption of water due to rainfall during the curing period. Therefore, when there is no rainfall during the dry curing period, it is good to give an appropriate amount of water on the way. Drying for 3 days or more can produce sand having a small particle size.

The product obtained by curing is classified by predetermined particle size by a classifier. As the classifier, for example, a sieve trembler is used.

In this classifier, the supplied product is first classified into components of more than 10 mm and components of 10 mm or less, and components of 10 mm or less are further classified into components of 5 to 10 mm and components of 5 mm or less.

The components 5 mm or less thus obtained are recovered as reclaimed sand, and the components 5-10 mm are recovered as reclaimed crushed stone.

On the other hand, the components exceeding 10 mm classified in the classifier are fed to a crusher such as an impeller, crushed, crushed to 10 mm or less, and then classified again into 5-10 mm components and 5 mm or less components. It is recovered.

In the present invention, by adjusting the compounding amount of the cement in the above range, most of the product supplied to the classification process is made of a small diameter component of 5 mm or less, and the reclaimed sand can be recovered with high efficiency without undergoing a crushing step.

2 is a flowchart showing Embodiment 2 of a recycling method of construction sludge according to the present invention.

In the method of Example 2, the dewatering cake obtained by dewatering sludge is first assembled by being fed to a kneader together with cement and water and, as necessary, the above-mentioned additives, and then assembled by feeding to a granulator.

In this method of Example 2, by using the raw material pre-trained in advance, the processing time in the granulator can be significantly shortened. Therefore, continuous processing is possible without a batch processing in a granulator, and processing efficiency can be improved significantly.

Then, the granulated product taken out from the granulator is sequentially subjected to the same process as in the method of Example 1, and finally, the component of 5 mm or less is recovered as reclaimed sand, and the component of 5 to 10 mm is Recovered as recycled stone.

3 is a flowchart showing Embodiment 3 of a recycling method of construction sludge according to the present invention.

The method of Example 3 combines the method of Example 1 and the method of Example 2, and more specifically, the granulated product (first assembly) obtained by the method of Example 1 and the example 2 The granulated product (second granulated product) obtained by the method is mixed, and the obtained mixture is subjected to the steps of curing, drying, classification, and crushing (if necessary) in the same manner as in the methods of Examples 1 and 2, and finally In other words, a component of 5 mm or less is recovered as reclaimed sand, and a component of 5 to 10 mm or less is recovered as reclaimed crushed stone.

The dehydrated cake obtained by dehydrating the construction sludge is supplied to the granulator (first granulator) with cement, water and, if necessary, additives, and then assembled, and the dehydrated cake obtained by dehydrating the construction sludge. The second granules obtained by supplying cement, water, and, if necessary, additives together with additives to a warming machine and then feeding them to a granulator (second granulator) are granulated, as shown in the test examples described below, and the particle size distribution, specific gravity, Since properties such as water absorption and abrasion reduction are different, two types of granulated materials having different properties can be mixed to adjust the properties such as particle size and specific gravity of the granulated materials in a balanced manner, and to obtain high quality reclaimed sand easily. Can be.

As a granulator used in the method of Example 1-Example 3 mentioned above, the thing (biaxial mixing mixer) of the structure shown by FIG. 4 and FIG. 5 is used, for example.

Fig. 4 is a front view of the granulator, and Fig. 5 is a plan view showing the interior of a treatment tank of the granulator.

The granulator 1 includes a processing tank 2 to which raw materials are supplied, two rotation shafts 3 installed in the processing tank 2 in parallel with each other and rotating in a reverse direction, and for rotating the rotation shafts 3. It comprises a motor (4) for.

A plurality of arms 5 are radially provided at two rotation shafts 3 provided in the processing tank 2 at predetermined intervals in the axial direction.

And the tip of these arms (5) has a crushing blade (6) for pressing the raw material against the inner wall of the processing tank 2, and a rake blade (7) for scraping off the raw material attached to the inner wall of the processing tank (2). Is installed.

The raw material supplied into the processing tank 2 is not biased due to the combination of the crushing action by the crushing wing 6 and the scraping action by the rake blade 7 provided on the two rotary shafts 3 rotating in opposite directions. By reliably kneading, the bulk raw material is crushed and gradually granulated, and discharged through a bottom discharge port (not shown) as a granulated product after a predetermined time has elapsed.

Further, in the method according to the present invention, instead of the structure shown in Figs. 4 and 5 as the granulator, one having a structure of the processing tank shown in Figs. 6 and 7 (screen feeder) can be used.

6 is a plan view schematically showing the structure of a treatment tank of a granulator, and FIG. 7 is a front view thereof.

The treatment tank 8 is a cylindrical tub provided with the axial direction in the vertical direction, and the screen 9 is provided at the lower part of the circumferential wall over the entire circumference. In addition, a rotary shaft 10 driven by a motor (not shown) is installed in the vertical direction in the inner center of the processing tank 8.

The rotating shaft 10 is provided with a stirring blade 11 extending in a substantially S-shape in plan view with the rotating shaft 10 in place, and a rake arm 12 is provided at a vertical position of the stirring blade 11. have.

The stirring blade 11 is installed at the lower position of the rotary shaft 10 so that its tip is close to the screen 9, and the raw material introduced into the processing tank 8 is crushed by granulation while granulating. Among the crushed granulated products, those having a certain particle size or less are extruded from the screen 9 to the outside.

The rake arm 12 is provided so that its tip contacts the inner wall of the processing tank 8 at the upper position of the screen 9, and scrapes off the raw material attached to the inner wall of the processing tank 8 and drops it downward. .

The raw material trained by the kneading machine is fed into the treatment tank 2 to be kneaded without being biased by a combination of the stirring action by the stirring blade 11 and the scraping action by the rake arm 12. As a result, the bulk raw material is crushed and gradually granulated, and the granulated granules having a certain particle size or less are continuously discharged to the outside through the mesh eye of the screen 9.

Any of the above two kinds of granulators can be used in Examples 1 to 3 of the method according to the present invention, but in the method of Example 1, the above-described biaxial mixing mixer type granulator (first granulator) is implemented. In the method of Example 2, it is preferable to use the above-mentioned screen feeder granulator (second granulator).

The reason for this is that when the raw material is directly supplied to the granulator for assembling, it is preferable to use a batch-type biaxial mixing mixer type granulator in order to reliably perform the assembly. In this case, since assembly can be performed in a short time, it is preferable to use a screen feeder granulator capable of continuous processing in order to improve processing efficiency.

Therefore, in the method of Example 3, which combines the method of Example 1 and the method of Example 2, it is preferable to use a biaxial mixing mixer type granulator as the first granulator and a screen feeder granulator as the second granulator.

<Example>

Hereinafter, the effect of the present invention will be clarified by showing examples of the method according to the present invention. However, this invention is not limited at all by the following example.

<Example 1>

Dehydration cake, cement, slag and gypsum obtained by dehydration of the construction sludge were used as raw materials, and granulation was made by kneading with the addition of water. The resulting granules were cured in water for one week to obtain a final product.

At this time, eight kinds of samples having 4%, 5%, 10%, 13%, 15%, 19%, 20%, and 25% of cement blended to the whole raw material as raw materials were prepared. The particle size and characteristics of the final product obtained in the case of using were investigated.

The raw material mixture ratio of each sample is shown in Table 1, and the measurement result of a particle size and a characteristic is shown in Table 2. In addition, the unit of a numerical value of Table 1 is g.

sample cement Oni slag gypsum No.1 40 823 68 68 No.2 50 819 66 66 No.3 100 771 64 64 No.4 130 746 62 62 No.5 150 729 61 61 No.6 190 691 59 59 No.7 200 686 57 57 No.8 250 643 54 54

sample Dry weight (t / ㎥) Particle size distribution (%) Absorption rate (%) 1 or less 1 to 2 2 to 5 5 or more No.1 1.998 23.2 40.1 34.7 2.0 30.01 No.2 2.182 29.0 28.7 38.3 4.0 27.30 No.3 2.187 31.2 31.6 32.4 4.8 25.87 No.4 2.210 29.8 17.2 48.2 4.8 24.33 No.5 2.258 24.2 21.1 48.8 5.9 24.11 No.6 2.321 18.2 27.3 47.9 6.6 24.97 No.7 2.380 13.8 19.8 56.2 10.2 23.81 No.8 2.369 15.3 22.4 51.6 10.7 24.24

As is clear from Table 2, when the blending amount of cement exceeds 13% by weight, more than 5% of components exceeding 5mm in particle size cannot be used as it is in the reclaimed sand. In this case, the shredding process is required separately.

In addition, when the blending amount of cement was 4% by weight, the final product obtained was particularly small, with a specific gravity of less than 2, and an absorption rate of 30% or more.

<Example 2>

In Example 1, the final product was obtained using what added incineration ash instead of gypsum as a raw material.

At this time, three kinds of samples (weight%) of cement as a raw material were made into two kinds of 15% and 10%, and three kinds of incineration ash contained three kinds of 7.5%, 12.5% and 15%. The particle size and characteristics of the final product obtained when each sample was used were investigated, respectively.

Table 3 shows the raw material mixture ratios of the samples, and Table 4 shows the results of the measurement of particle size and properties. In addition, the unit of a numerical value of Table 3 is g.

sample cement Oni slag Incineration No.1 15 70 7.5 7.5 No.2 15 70 0 15 No.3 10 70 7.5 12.5

sample Dry weight (t / ㎥) Particle size distribution (%) Absorption rate (%) 1 or less 1 to 2 2 to 5 5 or more No.1 2.437 25.88 30.30 38.70 5.12 23.290 No.2 2.801 25.68 34.21 35.13 4.98 25.800 No.3 2.435 33.96 22.36 39.47 4.21 24.340

From Table 4, it was found that when incineration ash was added instead of gypsum, a final product having a large specific gravity and a small component having a particle size larger than 5 mm could be obtained even when the amount of cement was the same.

<Test Example>

Table 5 shows the first assembly (assembly 1) obtained in the method according to Example 1 of the present invention (using the granulator shown in Figs. 4 and 5) and the method according to Example 2 (Figs. 6 and 7). It is a table | surface which shows the result of having tested the property of the 2nd granulated body (assembly 2) obtained by using the granulator shown, and the sludge (dehydration cake) which is a raw material, and FIG. 8 is a figure which shows the particle size curve.

Test Items Test result Standard value Particle size test (%) Oni Assembly 1 Assembly 2 Gravel powder 19mm9.5mm4.75mm2mm0.85mm0.425mm0.25mm0.106mm0.075mm 10098.293.289.186.282.281.1 10082.355.229.88.52.41.81.6 10087.964.140.924.715.110.75.44.0 Sand powder Fine grain powder Permeability test (cm / s) 3.49 × 10 ^-4 6.77 × 10 ^-2 8.34 × 10 ^-2 10 ^{-3 to} 1 (sand) Surface specific gravity (g / cm ³ ) - 1.986 1.783 - Dry weight (g / cm ³ ) - 1.563 1.246 2.5 or more Absorption rate (%) - 27.11 43.12 3.0 or less pH 12 11.8 11.9 - Abrasion Reduction Test (%) - 25.6 54.7 50% or more Modified CBR - 101 96 80 or more

As shown in Table 5 and FIG. 8, both the first and second assemblies were improved to be of high quality having a larger particle diameter and higher permeability than raw material sludge.

In addition, the first assembly had a higher specific gravity and a modified CBR value, a lower permeability and a lower wear rate than the second assembly. In addition, the second assembly contained the components from the large diameter to the small diameter in a balanced manner as compared with the first assembly. In addition, while the 1st assembly was an angular particle without an angle, the 2nd assembly was an angular square particle.

Such difference in properties of the granulated product is considered to be caused by the continuous processing in which the processing time (retention time) is shortened in the granulator since the granulation is carried out after the raw material is pre-conditioned in the method of Example 2.

As described above, according to the invention according to claim 1, a high quality reclaimed sand can be easily obtained from a construction sludge in which a conventionally effective recycling method has not been established with a simple facility configuration. In addition, since the granulated material is spontaneously divided during curing, high quality recycled sand can be efficiently recovered without requiring a crushing process.

According to the invention according to claim 2, since the raw materials are granulated after being drilled, the kneading processing time in the granulator can be shortened, and a large amount of raw materials can be continuously granulated and taken out, and the high quality recycling from the construction sludge can be achieved. The yarn can be obtained efficiently. In addition, since the granulated material is spontaneously divided during curing, high quality recycled sand can be efficiently recovered without requiring a crushing process.

According to the invention according to claim 3, it is possible to balance properties such as particle size, specific gravity, and the like of the granulated material in a balanced manner, and it is possible to reliably and easily obtain high quality reclaimed sand. In addition, since the granulated material is spontaneously divided during curing, high quality recycled sand can be efficiently recovered without requiring a crushing process.

According to the invention according to claim 4, the amount of cement used can be reduced, and at the same time, the slag that is a waste can be effectively recycled.

According to the invention according to claim 5, the amount of cement used can be reduced, and at the same time, incineration ash which is waste can be effectively recycled.

According to the invention according to claim 6, the amount of cement used can be reduced, and at the same time, gypsum which is waste can be effectively recycled.

According to the invention according to claims 7 to 10, it is possible to give an opportunity to naturally divide the granulated material in curing by moisture.

According to the invention according to claims 11 to 14, reclaimed sand can be obtained even at a location where water supply is difficult.

According to the invention according to claims 15 to 18, it is possible to give an opportunity to naturally divide the granulated material in the curing by moisture, so that the crushing treatment is not required even by dry curing.

According to the invention according to claim 19, since the apparatus can be continuously assembled without a batch treatment, the use thereof can greatly improve the treatment efficiency when producing recycled sand or recycled aggregate from construction sludge.

Claims (19)

The dehydrated cake and cement obtained by dehydrating the construction sludge are used as raw materials, and the blended amount of the cement is made 5% by weight or more and less than 20% by weight of the whole raw material, and these are supplied together with water to a granulator to granulate. After drying for a certain period of time, the dried granules are classified and the granulated substance having a predetermined particle size or less is recovered as reclaimed sand. The dehydration cake and cement obtained by dehydrating the construction sludge are used as raw materials, and the blending amount of the cement is 5% or more and less than 20% by weight of the whole raw material. And granulating the obtained granulated product after curing for a certain period of time, classifying the dried granulated product, and collecting granulated material having a predetermined particle size or less as a reclaimed sand. First assembly obtained by dehydrating cake and cement obtained by dehydrating construction sludge as a raw material, and blending the cement in an amount of not less than 5% by weight and less than 20% by weight of the whole raw material and supplying them together with water to the first granulator A granulated product obtained by mixing water and a second granulated product obtained by dehydrating cake and cement obtained by dehydrating the construction sludge as a raw material, supplying them with a kneader together with water to a kneader, and then feeding and granulating the second granulator. And drying after curing for a certain period of time, classifying the dried granules and recovering granules having a predetermined particle size or less as reclaimed sand. The method according to any one of claims 1 to 3, A recycling method of construction sludge, wherein slag is added as the raw material. The method according to any one of claims 1 to 3, Incineration ash was added as said raw material. The method according to any one of claims 1 to 3, Gypsum is added as said raw material, The recycling method of the construction sludge characterized by the above-mentioned. The method according to any one of claims 1 to 3, Said curing is performed in water, The recycling method of a construction sludge. The method of claim 4, wherein Said curing is performed in water, The recycling method of a construction sludge. The method of claim 5, wherein Said curing is performed in water, The recycling method of a construction sludge. The method of claim 6, Said curing is performed in water, The recycling method of a construction sludge. The method according to any one of claims 1 to 3, And said curing is performed by sun drying. The method of claim 4, wherein And said curing is performed by sun drying. The method of claim 5, wherein And said curing is performed by sun drying. The method of claim 6, And said curing is performed by sun drying. The method of claim 11, Recycling of the construction sludge, characterized in that to supply moisture to the granulated product during the curing period by the sun drying. The method of claim 12, Recycling of the construction sludge, characterized in that to supply moisture to the granulated product during the curing period by the sun drying. The method of claim 13, Recycling of the construction sludge, characterized in that to supply moisture to the granulated product during the curing period by the sun drying. The method of claim 14, Recycling of the construction sludge, characterized in that to supply moisture to the granulated product during the curing period by the sun drying. In the granulator for assembling the dewatering cake and cement obtained by dehydrating the construction sludge: A treatment tank having a screen on the circumferential wall; And a stirring blade for stirring the raw material introduced into the processing tank and extruding the granulated substance having a predetermined particle size or less from the screen to the outside.