JPH08103799A - Inorganic granular material - Google Patents

Abstract

PURPOSE: To provide an inorganic granular materials which can be used to form an artificial sandy plain for environmental preservation of a dredging area thereby to contribute for the environmental preservation, and which can be obtained by a simple method in which sedimentary sludge is granulated and sintered, so that a complete recycle of sedimentary sludge can be achieved. CONSTITUTION: In order to obtain inorganic granular naturals for artificial sands, before granulating sedimentary sludge, as raw material, large fragments of plants or shells, stones contained in the sludge are removed using a proper sieve, and the sludge is granulated by using, for example, a rolling, agitating granulating means, and then the granulated materials are sintered to obtain sintered materials. The sintered materials turn inorganic granular materials and organic materials in the sludge are burnt at the time of sintering and hence harmful organic materials of various kinds contained in domestic waste water, industrial waste water are burnt away and harmful heavy metals are stabilized by sintering. Thus a bad influence is not exerted on environment and the granular materials are not suspended in the water or do not contaminate water, and hence can be utilized as artificial sands.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inorganic granular material for artificial sand.

[0002]

BACKGROUND OF THE INVENTION Sludge accumulated in rivers, lakes, harbors, etc., so-called sludge, easily decomposes and gives off a bad odor because it contains a large amount of organic substances, and it also causes harmful effects to the environment because it contains harmful substances and harmful bacteria. Has become. As a method for treating such accumulated sludge, a method of dredging and discarding, a method of recycling as a raw material for ceramic products, etc. are being studied.

[0003]

However, since the accumulated sludge contains a large amount of harmful substances, if it is dredged and disposed of, there is a risk of secondary pollution, and it cannot be disposed of as it is.

Further, since dredging of accumulated sludge is usually carried out in a large amount in a relatively short period of time, when it is used as a raw material for ceramic products, there are problems in terms of storage and demand.

Further, since dredged sedimented sludge usually contains a large amount of water, it is necessary to perform dehydration and drying treatment, but it is also harmful, and it is difficult to make a profit in terms of treatment cost.

[0006]

In view of the problems of the prior art as described above, the present inventor has conducted earnest research to find an economical and effective means for treating accumulated sludge. As a result, after dredging the accumulated sludge, according to the method of granulating and firing this to obtain a fired product, it is possible to easily obtain the target product without completely drying the sludge once, The sludge can be treated very efficiently, and the resulting calcined product becomes an inorganic granular material in which harmful organic substances are incinerated and does not float in water or contaminate the water quality, resulting in excellent purification. Since it has an action, it can be used as artificial sand such as an artificial sandy beach, and it has been found that it can be effectively utilized even when a large amount of sludge is dredged and treated, and the present invention is completed here. Came to.

[0007] That is, the present invention relates to an inorganic granular material for artificial sand obtained by granulating and firing sedimented sludge.

In the present invention, the sedimentation sludge to be treated is not particularly limited in composition, water content, etc.
Sludge that accumulates in lakes and harbors, so-called sludge, can be used. In addition, used diatomaceous earth for filtration of industrial waste generated from beer manufacturing processes, sewage sludge, and the like can also be used. All of these accumulated sludges contain various organic and inorganic substances, but in the firing process described below, the organic substances are incinerated, harmful heavy metals, etc. are stabilized by sintering and granulated from inorganic materials. Is obtained.

In order to obtain the inorganic granular material of the present invention, it is first necessary to granulate the accumulated sludge as a raw material.
Prior to granulation, large plant debris, shells, stones, etc., contained in the accumulated sludge are preferably removed using a suitable sieve or the like. The granulation method is not particularly limited, and various known granulation means can be adopted. For example, various rolling and stirring granulators are used, and also a briquette machine, an extrusion granulator, a spray dryer and the like are used. And granulate. The particle size of the granulated product is not particularly limited and may be appropriately adjusted depending on the application, but when used as artificial sand for artificial beaches, it is usually about 0.5 to 20 mm. Good.

The water contained in the dredged sludge at the time of granulation can be used as water for granulation regardless of whether it is fresh water or seawater. Therefore, it is sufficient to dehydrate the water necessary for granulation. When the water content is too high and granulation is difficult, a suitable dehydration treatment, for example, precipitation treatment, centrifugal dehydration,
It is suitable to perform dehydration treatment by a method such as drying treatment or to add another dried powder material to adjust the water content suitable for granulation. The preferable water content at the time of granulation is not particularly limited because it varies depending on the granulating means and the like, but normally, the water content expressed by (water content / dry weight) × 100 may be about 20 to 40%. As the powder material which can be added for controlling the water content, a powder obtained by drying or calcining the sludge itself produced by the treatment step of the present invention can be used, and in addition, for example, diatomaceous earth, silica sand, crushed stone powder, shirasu, sewage. Sludge incineration ash, industrial waste incineration ash, etc. can be used.

Further, at the time of granulation, carboxymethyl cellulose (CM
Thickeners such as C), polyvinyl alcohol (PVA), clay and pulp waste liquid can be added. Further, in order to improve the sinterability in the firing step described later, if necessary, a slaked lime, water glass, phosphate, or other sinter material is added in an amount of 3 wt. % Can also be added.

Then, by firing the granulated product,
The inorganic particulate material of the present invention can be obtained. Prior to firing, the particle size of the granulated product can be adjusted by a method such as sieving, if necessary. The firing method is not particularly limited, and various known firing means may be appropriately adopted, but industrially, use of a rotary kiln, a shaft kiln or the like is suitable. The firing temperature must be a temperature at which an organic substance in sludge can be completely incinerated, and a fired product that does not easily collapse in water can be obtained, and may be appropriately set according to the composition of sludge, Usually 1000-1200 ° C
The firing temperature may be within a range of about.

In order to adjust the particle size by sieving and prevent the granulated material from collapsing in the firing step, it is preferable to carry out a drying treatment after the granulation step. The drying conditions are not particularly limited, and may be such that the granulated product is imparted with appropriate strength, and the drying temperature is usually about 80 to 120 ° C.

The calcined product obtained by the above method becomes an inorganic granular material, and the organic substances in the sludge are incinerated during the calcining, so that various harmful organic substances contained in domestic wastewater, industrial wastewater, etc. have disappeared. Since harmful heavy metals etc. are stabilized by sintering, they do not have an adverse effect on the environment. Moreover, since they do not float in water or pollute the water quality, they are useful as artificial sand. is there. In particular, by using the artificial sand made of the inorganic granular material of the present invention to construct an artificial sand beach in an area where the raw material sediment sludge has been dredged, it is possible to achieve complete recycling of the treated material and to reduce the accumulated sludge. Even if a large amount of dredging is processed, its use can be secured, and a large amount of applications according to the dredging plan can be secured.

Further, since the inorganic granular material can be made porous as compared with natural sand, it has a large surface area,
The artificial sandy beach is characterized by being excellent in purification action, and the artificial sandy beach using this inorganic granular material as artificial sand can contribute to environmental protection because it has a purification action. In addition, by laminating artificial sand made of the inorganic granular material on a river purification weir, and introducing river water into the artificial sand,
You can also clean the river.

Furthermore, the inorganic granular material of the present invention can be used to burn artificial organic sand for a certain period of time, then dredging and firing it again to incinerate organic substances adhering to the artificial sand. It has an excellent feature that it can be stabilized by sintering even if it adheres, and that it can be reused as an artificial sand having a good purification action for an artificial sand beach, a river purification weir, and the like.

[0017]

INDUSTRIAL APPLICABILITY The inorganic granular material for artificial sand of the present invention can be obtained by a simple treatment method such as granulation and calcination, and since it has a good purifying action, it contributes to environmental protection and can be regenerated. In particular, when it is used for the construction of artificial sandy beaches etc. for environmental conservation in the dredging area, it is possible to completely recycle the treated material and to accumulate a large amount of accumulated sludge. Even if it is dredged and treated, its use is secured. Therefore, the present invention provides an economical and effective means for treating accumulated sludge.

[0018]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 The following treatments were carried out using the accumulated sludge A collected from a freshwater lake at a depth of 1 m and the accumulated sludge B collected from a coast near the river mouth at a depth of 1 m.

Since all the collected sludge contained considerably large plant debris, shells, stones, etc., it was passed through a 5 mm sieve to remove it and put it in a container.
After 4 hours, the supernatant was removed and used as a sample. The composition of the sample is shown in Table 1 below.

[0021]

[Table 1]

For the accumulated sludge A, the water content ((water /
Dry weight) × 100) of 152%, 64% and 38% were prepared, and the accumulated sludge B having a water content of 34% was prepared and used. Dehydration for adjusting the water content was performed by opening the container containing the sample and natural drying.

Samples having the compositions shown in Table 2 below were made into granules having a diameter of 1 to 5 mm using a mixer-type granulator, and dried at 110 ° C. for 8 hours to give a base granule. And

Next, using an electric furnace, firing was performed under the conditions shown in Table 2 below to obtain an inorganic granular material.

The obtained inorganic granular material was placed in a flask, distilled water was added and immersed, the mixture was allowed to stand for 30 days and then stirred.
Immediately after that, the supernatant was observed. Further, a fixed amount of a dry sample was placed in a graduated cylinder, the weight thereof was measured, and the packed bulk specific gravity was determined by the dry weight / volume. Further, the water absorption rate ((water absorption amount / dry weight) × 100%) was determined according to the Gakushin method of magnesia clinker. The results are shown in Table 2 below.

[0026]

[Table 2]

From the above results, in the granular material of Sample No. 1, turbidity which seems to be caused by the collapse of the particles was generated,
All other samples showed no change and were judged to be suitable as artificial sand. In addition, each sample was judged to be excellent in the purifying action because of its large water absorption and large surface area.

Example 2 500 g of the granular material of sample No. 2 in Example 1 was placed in a fine sieve container having a diameter of 200 mm, and 500 c of the sludge A having a water content of 1000% was put on the granular material.
Then, the granular material was washed several times with the filtrate, drained, mixed, and re-fired at 1000 ° C. for 1 hour. With respect to the obtained recalcined product, the water absorption rate and the packed bulk density were measured in the same manner as in Example 1. The water absorption rate was 24.3%, the packed bulk density was 0.98, and no turbidity was observed in the immersion test. It turned out that it can be reused as artificial sand.

[0029]

Claims (2)

[Claims] 1. An inorganic granular material for artificial sand, which is obtained by granulating and burning sedimented sludge. 2. The inorganic granular material according to claim 1, which is used as artificial sand for an artificial sand beach or a river purification weir.