JPS61203195A - Preparation of soil conditioner - Google Patents

Abstract

PURPOSE:To prepare a soil conditioner with excellent soil conditioning and plant growth promoting effects at a low cost through utilization of sludge of construction work which is troublesome to dispose, by granulating preheated sludge of construction work and bringing the granules into contact with a high temp. gas for burning. CONSTITUTION:Sludge of construction work having a water content of 80% or higher (e.g. muddy waste water produced by spot pile driving) is predried to an average water content of 30-60% by drying in the sun and/or open air storage for dehydration and is formed into granules of about 1-10 mm in diameter by means of an appropriate granulating machine. The granules are brought into contact with a gas at 500-1,100 deg.C in a rotary kiln for burning, sterilization and drying to produce a soil conditioner having a water content of 20-40%, a lime content of 5-8%, a magnesium oxide content of 0.5-0.7%, a pH of 9 or higher and cation exchanging ability.

Description

[Detailed description of the invention] Industrial application field The present invention is applicable to construction sludge (bridge/viaduct construction, reinforcing bars/steel frames,
This invention relates to a method for producing a soil conditioner made from waste mud water generated from cast-in-place pile construction during construction work such as new construction of concrete and stone buildings.

BACKGROUND OF THE INVENTION In recent years, it has become difficult to dispose of industrial waste, and there is an urgent need to develop ways to reuse it from the viewpoint of resource and energy conservation.

The construction sludge mentioned above is of course industrial waste 1ai,
In particular, it is difficult to treat it due to the huge amount generated and the state of waste mud water, and the current situation is that it costs a huge amount of money to dispose of it, and there are no effective proposals for its reuse. Not done.

On the other hand, mineral-based soil improvers are generally known, but because they are used in large quantities for their purpose,
The development of cheaper raw materials is desired.

Problems to be Solved by the Invention Therefore, the purpose of the present invention is to effectively utilize the construction sludge described above, which is difficult to process, and to replace it with a soil conditioner mainly composed of the minerals mentioned above, and to produce soil with vine quality. The object of the present invention is to produce an improver from construction sludge at an extremely low cost.

Means for Solving the Problems The above objects of the present invention are achieved by a method in which construction sludge is pre-dried, granulated, and calcined by contact with high-temperature gas. The soil conditioner thus obtained is harmless to plants, and its effects on soil improvement and plant cultivation are comparable to those of conventional soil conditioners, making it fully useful as a substitute.

Aspects of the Invention Next, each step of the method for producing the soil conditioner of the present invention will be explained in detail.

(cL) Pre-drying First, construction sludge is pre-dried to a moisture content that makes it easy to granulate. Construction sludge generally has a water content of Figo% or higher, with an average moisture content of 3% depending on the type of granulator in which it is used.
Dry to about 0 to 60%, preferably about 40 inches.

Any desired method can be used for this pre-drying, but considering the huge amount of processing involved, it is actually preferable to use solar drying and/or open storage dehydration as shown in the flow sheet shown in the drawing. be. In solar drying, dehydration is carried out under the sun by layering the sludge thinly.On the other hand, in open storage dehydration, construction sludge is stored in a storage tank (the surface is covered with a sheet), and the moisture contained in the sludge is removed. The water is dehydrated by gravity sedimentation and partial evaporation from the surface, and if both methods are employed, either method may be performed first. Normally, construction sludge with a water content of about GSS is dehydrated to an average moisture content of 50% by drying in the sun for about 13 days, and to less than 40% by subsequent storage in the open (about 24 days).

(Pelletization and molding) The construction sludge pre-dried as described above is then granulated and molded into the desired granule amount using an appropriate granulator. Examples of granulators include transfer type, extrusion type, etc. In the case of a type of granulator that performs this as an intermediate step, a molding step may be added.The particle size is approximately 1 to 1,000 yen, considering the purpose of the soil conditioner. 1゜■,
Preferably about 5 to 6 m is desirable.

CC) The calcined granulated construction sludge is then heated to a high temperature, e.g.
The granulated material is brought into contact with a high temperature gas of 1100 DEG C., preferably about 800 DEG to +00 DEG C., to sterilize and dry the granulated material at the same time as firing it. In practice, this firing step is preferably carried out using a rotary kiln. .

As described above, depending on the construction sludge used, the water content is 20~20~
40%, about 5-8 qb of lime, about 0.5-0.7 magnesium
To, a soil conditioner having a cation exchange ability of pH 9 or higher is obtained. The obtained soil conditioner is then cooled (natural cooling or forced cooling may be used), weighed, and subjected to total tS before being shipped as a product.

Note that it is useful to use waste tires as the main fuel that is the heat source in the firing process from the viewpoint of resource and energy conservation. For example, as shown in the drawing, a fixed amount of waste tires are charged into a gas carbonization generating furnace, high temperature combustion gas is generated by a carbonization gas combustion method, and temperature is controlled by controlling the gas flow rate. After the fuel is completely burned, it is treated until it becomes a white ash. Post-processing is facilitated by such treatment, and air pollution countermeasures are taken by installing exhaust gas and dust collectors.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples and Test Examples.

Example Construction sludge with an average moisture content of 86% (Yotsukaido Chuo Kosan) was dried in the sun, stored in an open area, dehydrated, pre-dried to a moisture content of 40% or less, and then granulated using a granulator to reduce the moisture content to about 5% on average. ~6■
It was granulated to obtain particles of . This was passed through a ToRo type rotary kiln which had been previously heated by burning gas, and was burned and sterilized by contact with high-temperature gas at 800 to 1000°C, and then cooled to obtain a soil conditioner according to the present invention.

The analysis results of the soil conditioner were as follows: ◎ Moisture (H,0) 27.98% Total amount of lime (C
ab) 5.46% total amount of magnesia (MIIO)
Q, 56 cation exchange capacity 31, 3 maq/
Dry ± too II pH < spot 5 ll1500 ad,
16°C) 10.6 Test Example 1 (Cultivation Test) In order to find out whether and to what extent the application of the soil conditioner obtained in the above example would cause problems with germination and post-germination growth, A plant test was conducted. The test conditions and results are shown below.

(i) Test conditions (a) The types or names of the test samples and control samples and their analytical results are as shown in Table-1.

Table-1 (b) Soil properties of test crushing, alluvial soil or diluvial soil -
2 (c) Types and varieties of test crops (Komatsu Nani) Fertilization design and name of test area -3 Note 1. For control sample CaO and MliO(7) applications.

Calcium carbonate and magnesium carbonate were used in amounts corresponding to the applied component amounts of the test samples in each test area.

Note 2 In addition to the application amounts and component amounts for both the test and control samples listed in the table above, the following values were applied to all test plots including the standard plot:
25jlF as N, P, O, and 0, respectively.
Ammonia sulfate, lime superphosphate, and chloride were applied in amounts equivalent to 50"F and 25111PK (Standard Area B only applied ternary fertilizers).

(e) Cultivation method table -4 (2) Management status Soil light fertilizer application port (3) Germination after 1Fj in the test started 2 days after fli, and there was a difference in the start date of germination between the test and control samples. was not seen.

In both the test and control sample plots, there was no noticeable difference in growth in the early stages after germination, but as the number of days passed, the growth in the test sample plot slightly exceeded that of the control sample, and this growth difference was due to convergence.
The live weight at 4:1F was also affected. Table of investigation acid #
5.

Table 5: Germination and Growth Survey Results As is clear from the above test results, the germination and subsequent growth of Komatsuna by applying the soil conditioner produced from the construction sludge of the present invention is significantly affected by calcium carbonate and magnesium carbonate. Results were equal to or better than those obtained with the control fertilizer used in combination, and no adverse effects on vegetation were observed.

Test Example 2 (Soil acidity correction test) In order to find out the acidity correction ability of the soil conditioner according to the present invention, a test was conducted using two different types of soil.

(1) Test method: Put the test soil and the soil conditioner produced in the above example in a certain ratio in a +00 gLt beaker, mix well, and then add water to the field condition (approximately 60% of the maximum water capacity). The mixture was then covered with aluminum foil, placed in a thermostat at 27°C, and taken out every designated survey day, and 50% water was added thereto.The mixture was stirred occasionally with a glass bowl and allowed to stand for over 1 hour. The pH of the supernatant was measured.

(B) Test area Table-7: Test A Table-8: Test B Note) pH of the mixed applied soil conditioner (H2O) / 10.6 (2) Test results pH by survey date The changes are as follows.

Table-9: Test A Table-10: Test B As can be seen from the above test results, the soil conditioner of the present invention was applied to humic volcanic ash soil and hard acidic soil. It was recognized that it has an acidity correction effect.

Plants have an optimum pH range; for example, peas, sugar cane, and spinach have an optimum pH of 6.5 to 7.0, asparagus, green beans, barley, capocha, cauliflower, kambo, cucumber, wheat, taro, watermelon, Chinese cabbage, green onion, etc. Eggplant, tomato, chrysanthemum, chrysanthemum,
Most plants such as cyclamen have a pH of 6.0 to 6.5, while rice, cabbage, radish, Komatsuna, etc. have a pH of 5.5 to 6.
．． 5. Plum, buckwheat, rakkyo, etc. have a pH of 5.5-6.
It is 0. However, the humic volcanic ash soil has a pH of 5,
5. Hard acidic soil has a pH of 5.0, making it difficult to grow most plants; however, by applying the soil conditioner of the present invention, acidic soil can be improved into soil that is optimal for plant cultivation. The amount of application can be easily determined at an appropriate rate according to the target plant and the applied soil.

Effects of the Invention As described above, according to the present invention, a soil conditioner having soil improvement and plant growth effects comparable to or better than conventional ones can be obtained from construction sludge, which is industrial waste.

Furthermore, since the raw material is construction sludge, which is industrial waste, it can be produced at an extremely low cost, and is extremely useful from the standpoint of resource conservation and industrial waste treatment.

[Brief explanation of the drawing]

The drawing is a 70-sheet showing one embodiment of the method of the invention.

Claims (1)

[Claims] A method for producing a soil conditioner from construction sludge, which comprises pre-drying the construction sludge, granulating it, and calcining it by contact with high-temperature gas.