JPH045709B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial application field The present invention is applicable to construction sludge (bridge/viaduct construction, reinforcing steel/
This article relates to a method for producing a soil conditioner from waste mud water generated during cast-in-place pile construction during construction work such as new construction of steel-framed, concrete, and stone buildings. BACKGROUND ART In recent years, it has become difficult to dispose of industrial waste, and there has been an urgent need to develop and reuse it from the viewpoint of resource and energy conservation. The above-mentioned construction sludge is of course a type of industrial waste, and it is difficult to treat it due to the huge amount generated and the state of waste mud water. At present, no effective proposals have been made for its reuse. On the other hand, mineral-based soil conditioners are generally known, but because they are used in large quantities for their purpose, there is a desire to develop cheaper raw materials. Problems to be Solved by the Invention Therefore, an object of the present invention is to effectively utilize the construction sludge described above, which is difficult to process, and to provide a soil conditioner that has quality that can be substituted for the mineral-based soil improvement agent mentioned above. The purpose of the present invention is to produce a soil conditioner from construction sludge at an extremely low cost. Means for Solving the Problems The object of the present invention is to pre-dry construction sludge, then granulate it, and sinter it by contacting with high-temperature gas of 1100°C or less to reduce the moisture content to 20%.
~40%, lime content 5-8%, magnesia 0.5-0.7%, PH9
This can be achieved by obtaining a soil conditioner having the above cation exchange ability. 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. (a) 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 80 or higher and is dried to an average moisture content of about 30-60%, preferably about 40%, depending on the type of granulator used. Any desired method can be used for this pre-drying, but considering the huge throughput, it is actually preferable to use solar drying and/or open storage dehydration as shown in the flow sheet shown in the drawing. . 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 removed by gravity sedimentation and partial evaporation from the surface; if both methods are employed, either method may be performed first. Normally, construction sludge with a water content of about 85% is dried in the sun for about 13 days to an average moisture content of about 50%, and then stored in the open (about 24 days).
Dehydrated to less than 40%. (b) Granulation and molding The construction sludge pre-dried as described above is then granulated and molded into the desired granule shape using a suitable granulator. Various types of granulators can be used, such as a rolling type and an extrusion type. In the case of a type of granulator that performs this as an intermediate step, a molding step may be added. From the viewpoint of the purpose as a soil conditioner, the particle size is approximately 1 to 1.
The thickness is preferably about 10 mm, preferably about 5 to 6 mm. (c) Calcination The granulated construction sludge is then brought into contact with high-temperature gas, for example at about 500 to 1100°C, preferably about 800 to 1000°C, to perform sterilization and drying at the same time as calcination in the granulator. Do this. Note that if it is not necessary to carry out sterilization so strictly, baking and drying can be carried out satisfactorily even at a high temperature of about 200°C. 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 about 20-40%, the lime content is about 5-8%, and the magnesium is about 0.5-0.7.
%, a soil conditioner having a cation exchange ability of PH 9 or higher can be obtained. The obtained soil conditioner is then cooled (either natural cooling or forced cooling), inspected, weighed, etc., and then shipped as a product.
In addition, in order to obtain the above soil conditioner,
As a starting material, construction sludge with a water content of 80% or more containing 1.7 to 4.4% lime and 0.17 to 0.38% magnesium on an oxide basis in terms of a water content of 86% may be used. 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 is 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 dust collectors, etc. EXAMPLES The present invention will be specifically described below with reference to Examples and Test Examples. Example: Construction sludge with an average moisture content of 86% (Yotsukaido Chuo Kosan)
After pre-drying in the sun and storing and dehydrating in an open field to a moisture content of 40% or less, it was granulated using a granulator to obtain particles with an average size of about 5 to 6 mm.
This was passed through a rotary kiln previously heated by ToRo type gas combustion, calcined 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 ₂ O) 27.98% Total amount of lime (CaO) 5.46% Total amount of magnesia (MgO) 0.56% Cation exchange capacity 31.8meq/100g dry soil PH (5g actual/500ml, 16℃) 10.6 Test example 1 (cultivation) Test) A seedling test was conducted in order to determine whether and to what extent the application of the soil conditioner obtained in the above example would cause any hindrance to the germination and post-germination growth of Komatsuna. The test conditions and results are shown below. (1) Test conditions (a) The types or names of test materials and control samples, as well as the analytical results, are as shown in Table-1.

[Table] Used as a measure of the strength of the soil.
Note) CEC is the cation exchange capacity expressed in units of milliequivalents per ±100 g of dry soil, and is used as a measure of soil fertility. (b) Soil properties of the test soil, whether it is alluvial soil or flood soil, etc.

【table】 (c) Types and varieties of test crops small (d) Fertilization design and test area name

【table】

【table】 (e) Cultivation method

[Table] (2) Management status Soil filling Fertilization date (3) Test results Germination started two days after seeding, and there was no difference in the start date of germination between the test and control samples. There was no noticeable difference in growth between the test and control sample plots in the initial growth after germination, but as the days passed, the test sample plot's growth slightly exceeded that of the control sample, and this growth difference was observed during the yield survey. The biomass was also affected. The survey results are shown in Table-5.

[Table] As is clear from the above test results, the germination and subsequent growth of komatsu by applying the soil conditioner made from construction sludge of the present invention is equivalent to that by using a control fertilizer containing calcium carbonate and magnesium carbonate. It showed results above or above, and no results that caused problems with 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 After thoroughly mixing the test soil and the soil conditioner manufactured in the above example in a 100ml beaker at a certain ratio, water was added to adjust the field condition (approximately the maximum water capacity).
60%), covered with aluminum foil, and
The mixture was placed in a constant temperature chamber at °C, taken out every predetermined survey day, 50 ml of water was added thereto, stirred occasionally with a glass rod, and allowed to stand for over 1 hour, and then the pH of the supernatant liquid was measured. (b) Test soil

【table】 (b) Test area

【table】

【table】

【table】 (2) Test results Changes in PH by survey day are as follows.

【table】

[Table] As can be seen from the above test results, when the soil conditioner of the present invention was applied to humic volcanic ash soil and hard acidic soil, it was found that the soil conditioner of the present invention had an acidity correction effect on both types of soil. Admitted. Plants have an optimal PH range, for example, peas,
Sugarcane, spinach, etc. have a pH of 6.5 to 7.0, and most plants, such as asparagus, green beans, barley, pumpkin, cauliflower, campiyou, cucumber, wheat, taro, watermelon, Chinese cabbage, green onion, eggplant, tomato, Chinese cabbage, and cyclamen, have a pH of 6.5 to 7.0.
6.0-6.5, rice, cabbage, radish, Komatsuna, etc. have a PH of 5.5-6.5, and plums, buckwheat, radish, etc. have a PH of 5.5-6.0. However, the humic volcanic ash soil has a pH of 5.5 and hard acidic soil has a pH of 5.0, making it difficult to cultivate most plants. It is possible to improve the soil to the optimum level. The application amount can be easily determined at an appropriate rate depending on 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 superior to 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 drawings]

The drawing is a flow sheet illustrating one embodiment of the method of the invention.

Claims (1)

[Claims] 1 Calcium content 1.7 based on oxides based on moisture content of 86%
Moisture content 80% containing ~4.4%, magnesia 0.17~0.38%
After pre-drying the above construction sludge, it is granulated and molded.
Calcined by contacting with high temperature gas below 1100℃, moisture 20-40%, lime content 5-8%, magnesia
A method for producing a soil conditioner from construction sludge, characterized by obtaining a soil conditioner having a cation exchange capacity of 0.5 to 0.7% and a pH of 9 or higher.