JP2000044362A - Production of inorganic porous material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inorganic porous material having a large cation exchange capacity by using molding sand discharged from a foundry and containing bentonite in a specific amount as a main raw material, forming a granular or massive material from the molding sand and subsequently calcining the formed granular or massive material at a specific temperature. SOLUTION: A raw material which consists mainly of molding sand discharged from a foundry and contains bentonite contained in the molding sand in an amount of >=5 wt.% based on the molding sand is used, subjected to the adjustment of water content and then processed to form a granular or massive material having a granule diameter of about l-20 mm. The formed granular or massive material is naturally or thermally dried and subsequently calcined at 400-600 deg.C for 2-5 hr to obtain the inorganic porous material having a large strength and a cation exchange capacity of >=10 me/100 g. A proper raw material includes waste sludge comprising the mixture of dirt containing molding sand discharged from the production line of a foundry with the dirt of the domestic waste water of the foundry, etc., and waste dust such as collected dust discharged from the foundry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an inorganic porous material which is excellent as a soil improving material and an artificial soil for plants.

[0002]

2. Description of the Related Art Conventionally, as a method for producing an inorganic porous body, there has been known a method in which water is added to kneaded fine sand derived from used foundry sand discharged from a foundry, kneaded and molded, and a molded product is fired. (JP-A-8-59365).

[0003]

In the above-mentioned conventional method for producing an inorganic porous material, fine sand generated from a green sand mold is used as fine sand derived from used foundry sand discharged from a foundry.
Alternatively, a mixed fine powder sand obtained by adding a small amount of fine sand generated from an organic sand mold to fine sand generated from a raw sand mold is used, and these fine sands are kneaded with water, molded, and air-dried or forcibly dried by heat or the like. , Preferably 600 to 1100
C., particularly preferably 800 to 1000.degree. C. for a predetermined time to form an inorganic porous body. However, the present inventors have investigated and studied the properties of the inorganic porous material thus obtained, and found that the inorganic porous material has a small cation exchange capacity (CEC) indicating a capacity to retain plant nutrients. Became clear. Therefore, an object of the present invention is to provide a method for producing an inorganic porous body that can obtain an inorganic porous body having a large cation exchange capacity.

[0004]

The present inventors have made intensive studies to solve the above-mentioned problems. As a result, the present inventors found that bentonite used as a binder was added to fine sand generated from green sand mold discharged from a foundry. Contained, the bentonite has a large cation exchange capacity, but it has been found that the cation exchange capacity of bentonite is reduced by heating, and becomes significantly smaller when heated to 600 ° C. or more. Based on such findings, the present inventors have formed granules or aggregates from molding sand containing bentonite, and
By heating the mixture to a temperature of not less than 600 ° C. and less than 600 ° C., it was possible to obtain an inorganic porous material having a large cation exchange capacity. The present invention forms a granular material or an agglomerate from a raw material whose main component is foundry sand discharged from a foundry, and the amount of bentonite contained in the foundry sand is 5% by weight or more of the foundry sand, The granular material or the massive material is heated at 400 ° C. or more to 60 ° C.
It is characterized by heating to less than 0 ° C. and firing.

When the amount of bentonite contained in the foundry sand is 5% by weight or more of the foundry sand, if the amount of bentonite is less than 5% by weight, the cation exchange capacity of the obtained inorganic porous material is small. It is because it becomes. From the viewpoint of increasing the cation exchange capacity of the inorganic porous body,
The amount of bentonite in the foundry sand is desirably 10% by weight or more. The reason why the heating temperature is set to 400 ° C. or higher and lower than 600 ° C. is that at a heating temperature lower than 400 ° C., the strength as an inorganic porous body is reduced and the shape retention is deteriorated. This is because the cation exchange capacity of the porous body is reduced. In the present invention, when the granular or lump formed from the above raw materials is fired, the strength is high and the cation exchange capacity is 10 me / 10
An inorganic porous body of 0 g or more is obtained.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a raw material whose main component is foundry sand discharged from a foundry and the amount of bentonite contained in the foundry sand is 5% by weight or more of the foundry sand, a production line of the foundry is used. Dust disposal such as sludge waste containing casting sand discharged from the factory mixed with mud of household wastewater (including toilet water and canteen wastewater), and dust collected from the foundry Things can be used. When forming a granular material or a lump from the raw material, if the water content of the raw material is large, dewater the material, and if the water content of the raw material is small, mix the raw material and water, and the raw material has a predetermined shape. The water content of the raw material is adjusted to such an extent that it can be held. The granules or the lump are preferably air-dried or forcibly dried by heat or the like and then heated and fired. The heating time of the inorganic porous body depends on the temperature at which the inorganic porous body is heated and the size of the inorganic porous body. , 60
When heating at around 0 ° C., it is desirable to set it to 2 to 4 hours.

[0007]

Embodiments of the present invention will be described below. As a first embodiment, a case where a cake-like sludge material is used as a raw material will be described. The sludge material is obtained by filtering sludge waste collected in a wastewater reservoir of a foundry for manufacturing cast iron with a filter press and drying it appropriately by sunlight or heat treatment to form a cake. The sludge contains 85% by weight of dust components discharged from the production line of the foundry, and 15% of organic components discharged from domestic wastewater (including toilet water and canteen wastewater) of the foundry. %include. 95% by weight of the dust component is foundry sand, and the foundry sand contains bentonite at 10% by weight of the foundry sand.

After drying the sludge material, it was finely pulverized, and the pulverized sludge material was accommodated in a kneader, and kneaded by appropriately adding water. Next, the kneading material is charged into a granulation container provided with stirring blades, and the stirring blades are rotated by a motor to granulate the granular material. The particle size of the granules can be arbitrarily set by adjusting the granulation time. In this example, granules having an average particle size of 3 mm were granulated.

Next, the granules were heated at 110 ° C. for 60 minutes and dried to remove water from the granules, and the dried granules were heated in a rotary kiln and fired. The firing conditions of the example were changed in three stages, and the firing conditions of the comparative example were changed in two stages. In the firing condition of Example 1, the rotary kiln was fired for 4 hours at an outlet temperature of 500 ° C. In the firing condition of Example 2, the outlet temperature was 600 ° C. for 3 hours, and in the firing condition of Example 3, the outlet temperature was 68 hours.
Firing was performed at 0 ° C. for 3 hours. Under Comparative Example firing conditions 1, the outlet temperature was 450 ° C., and firing was performed for 4 hours. Under Comparative Example firing conditions 2, the outlet temperature was set at 750 ° C., and firing was performed for 3 hours. Example porous body 1 obtained under example firing condition 1, example porous body 2 obtained under example firing condition 2, and example porous body 3 obtained under example firing condition 3. For the comparative example porous body 1 obtained under the comparative example firing condition 1 and the comparative example porous body 2 obtained under the comparative example firing condition 2, the temperature at which each porous body was discharged from the rotary kiln, The actual heating temperature, strength, porosity, and cation exchange capacity (CEC) of the porous body were measured. As for the heating temperature of each porous body, the temperature at which each porous body was discharged from the rotary kiln outlet was measured by an infrared thermometer. The strength of the inorganic porous material (target diameter 3m)
m) was placed thereon, and the horizontal table was raised at a low speed, whereby the inorganic porous body was pressed against the pressurized cage body above the horizontal table, and the load when the inorganic porous body was crushed was measured. The porosity was measured by a mercury porosimeter, and the cation exchange capacity was measured by the Schollenberger method (“Soil Standard Analysis and Measurement Method”, pp. 150-154, edited by Soil Standard Analysis and Measurement Method Committee, Hiroyusha). Table 1 shows the results.

[0010]

[Table 1]

As is clear from Table 1, the porosity is 30% or more in each case, and the permeability and water retention as an inorganic porous body are ensured. In the body 1, the comparative example porous body 2 having a large cation exchange capacity but a small strength and a heating temperature of 647 ° C.
Had significantly smaller cation exchange capacity.

As a second embodiment, a case where dust discharged from a dust collector of a foundry is used as a raw material will be described. The dust consists of fine foundry sand, and 15
Contains bentonite by weight.

[0013] The dust is stored in a kneader, water is added as needed, and the mixture is kneaded. The kneaded material is put into a granulation vessel equipped with stirring blades, and then the stirring blades are rotated by a motor to make an average. Granules having a particle size of 3 mm were granulated.

Next, the granules were dried by heating at 110 ° C. for 60 minutes to remove moisture from the granules, and the dried granules were heated in a rotary kiln and fired. The firing conditions were the same as the firing conditions of the first embodiment, and the firing conditions of the example were changed in three stages, and the firing conditions of the comparative example were changed in two stages. In Example firing condition 4, the rotary kiln was fired for 4 hours at an outlet temperature of 500 ° C., in Example firing condition 5, the outlet temperature was 600 ° C. for 3 hours, and in Example firing condition 6, the outlet temperature was 680 ° C. In the firing condition 3 of the comparative example, the outlet temperature was set at 4
Firing was performed at 50 ° C. for 4 hours, and under the firing conditions of Comparative Example 4, the outlet temperature was set to 750 ° C. for 3 hours. Example porous body 4 obtained under Example firing condition 4 and Example firing condition 5
Example porous body 5 obtained in Example 1, Example porous body 6 obtained in Example firing condition 6, Comparative example porous body 3 obtained in Comparative example firing condition 3, and Comparative example firing condition 4 In the comparative example porous body 4 obtained in the above, the temperature at which each porous body is discharged from the rotary kiln, that is, the actual heating temperature, strength, porosity, and cation exchange capacity of each porous body ( C
EC). Each measuring method is the same as that in the first embodiment. Table 2 shows the results.

[0015]

[Table 2]

As is clear from Table 2, the porosity is 30% or more in each case, and the air permeability and the water retention as the inorganic porous body are ensured. In Comparative Example Porous Material 3 at 381 ° C., the cation exchange capacity was large but the strength was small, and the heating temperature was 638 ° C.
Comparative example porous body 4 had a significantly small cation exchange capacity.

[0017]

According to the present invention, a granular material is prepared from a raw material containing a molding sand discharged from a foundry as a main component and having a bentonite content of 5% by weight or more of the foundry sand. Or forming a lump, and baking the particle or lump by heating it to 400 ° C. or more and less than 600 ° C.
The cation exchange capacity of the obtained inorganic porous material is 10 me /
Since it is 100 g or more, it has a cation exchange capacity equivalent to that of Ando soil and brown forest soil, and when mixed in soil, keeps the cation exchange capacity of the mixed soil high and improves air permeability etc. And promote the growth of plants.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hitoshi Yoshimi 1 No. 1 Tenno, Takaokashinmachi, Toyota City, Aichi Prefecture F-term in Aisin Takaoka Co., Ltd. 4G019 GA04 4H026 AA01 AB04

Claims (1)

[Claims] 1. A method of forming a granular or agglomerate from a raw material containing a foundry sand discharged from a foundry as a main component and having an amount of bentonite in the foundry sand of 5% by weight or more of the foundry sand. , The granular material or the massive material is heated at 400 ° C. or more to 600 ° C.
A method for producing an inorganic porous body, characterized in that the inorganic porous body is heated to a temperature of less than ° C and fired.