JPH09278557A - Porous sintered product, and water-purifying material comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a porous sintered product having uniformly distributed pores, excellent in strength and gas permeability, and capable of adsorbing and photochemically decomposing organic substances, etc., over a long period, and to obtain a water-purifying material comprising the same. SOLUTION: This porous sintered product is obtained by adding water to the collected mixture dust of inorganic oxides containing at least zinc oxide and evaporated from a smelting furnace for cast iron, kneading the mixture, molding the kneaded product, and subsequently sintering the molded product. A water-floating porous sintered product is obtained by combining the above porous sintered product with another sintered product such as a water-floating sintered product or with a sintering raw material having a bulk specific gravity of <=0.5. This water-purifying material comprises the porous sintered products.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a porous sintered body that exhibits excellent performance as a water purification material for a long period of time.

[0002]

2. Description of the Related Art In recent years, interest in environmental issues has increased,
In Japan as well, the industry, academia and government are working on countermeasures. Specifically, legislative measures regarding waste treatment / recycling, etc. are taken, and accordingly, companies are required to develop innovative technologies to achieve harmony between environmental protection and economic efficiency.

Even in the casting industry, a large amount of sand, dust and the like to be discarded is generated in each casting process.
Although these sands and dusts are recycled and recycled as much as possible, a large amount of sands and dusts that cannot be reused are still generated even if they are recycled, and they are disposed of by landfilling.

[0004]

However, landfilling the waste sand and dust that cannot be reused requires not only a considerable cost but also a limit in the landfill site.

The present invention uses a mixture dust such as an inorganic oxide containing at least zinc oxide generated from a furnace that melts a cast iron raw material, has pores uniformly distributed, is excellent in strength and air permeability, An object of the present invention is to provide a sintered body capable of adsorbing an organic substance and the like and photodecomposing for a long period of time, and a water purification material comprising the same.

[0006]

In order to achieve the above object, the present invention is to knead by adding water to a mixture dust of an inorganic oxide containing at least zinc oxide evaporated and collected from a melting furnace for cast iron. It is a porous sintered body obtained by firing a molded product that has been molded.

According to the present invention, the mixture dust of the inorganic oxide containing at least zinc oxide evaporated from the melting furnace for cast iron and collected, and the raw material for forming a sintered body having a bulk specific gravity of 0.5 or less and water are kneaded. It is a water-floating porous sintered body obtained by firing a molded product.

According to the present invention, a paste obtained by adding water to a mixture dust of an inorganic oxide containing at least zinc oxide, which has been evaporated and dust-collected from a melting furnace for cast iron and kneaded, is formed by adhering it to a sintered body. It is a porous sintered body obtained by firing a product.

According to the present invention, water is added to a mixture dust of a mixture of inorganic oxides containing at least zinc oxide, which has been evaporated and collected from a melting furnace for cast iron, and the mixture is kneaded to make it adhere to a water-floating sintered body. Obtained by firing a molded product molded by
It is a water-buoyant porous sintered body.

The present invention is the above-mentioned porous sintered body, characterized in that the molded body is dried before firing.

Further, the present invention is a water purification material characterized by comprising each of the above-mentioned porous sintered bodies.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The dust used for producing the porous sintered body of the present invention is fine particles of a mixture of inorganic oxides containing at least zinc oxide, which are evaporated and collected from a melting furnace for cast iron. is there. In general, cast iron is a raw material for iron such as pig iron or iron scrap, a carburizing agent such as coke, a solvent such as limestone or fluorite, and Mg, Ni-Mg alloy, Cu-Fe-Si-.
Mg alloy, Fe-Si-Mg alloy, Fe-Si-Mg-
Ca alloy, Mg-coke, Ca-Si rare earth element or calcium chloride coating, MgF ₂ -rare earth fluoride-Ca
A mixture of -Si and an additive material such as CeLa are added and melted at, for example, 1500 to 1600 ° C in a melting furnace such as a cupola, an arc furnace, an induction furnace, a reverberation furnace, and a rotary furnace. Since a large amount of zinc-coated iron plate is usually used as this iron raw material, a mixture of inorganic oxides containing a large amount of zinc oxide is evaporated during melting and is recovered as dust in the dust collector of the melting furnace. . The components of this dust and the ratio thereof differ depending on the raw materials used, but usually zinc oxide (Zn oxide) as the main component is used.
O), MgO, Al ₂ O ₃ , SiO ₂ , P ₂
O ₅ , SO ₃ , K ₂ O, CaO, Cr ₂ O ₃ , MnO,
It contains one or more kinds of inorganic oxides such as Fe ₂ O ₃ and PbO, and may further contain Cl, Ce, La, Ac.
Etc. are included. Zinc oxide, which is the main component of dust, is a photoreactive semiconductor, and the dust in the present invention in which it is mixed with one or more of the above inorganic oxides is used as a photoreactive semiconductor of zinc oxide due to these inorganic oxides. It is considered that the property of is significantly promoted. The particle size of the collected dust is usually 10 to 30 μm.

The bulk specific gravity used in the present invention is 0.5.
Examples of the raw material for forming a sintered body below include hollow closed-cell particles obtained by heating and expanding volcanic eruption glass particles containing silica or alumina as a main component, and the particles have, for example, an average particle diameter of 37 μm to In the case of 1.6 mm, the bulk specific gravity is 0.07 to 0.5. Such a raw material for forming a sintered body having a bulk specific gravity of 0.5 or less is used by mixing with the dust collected from the melting furnace for cast iron, kneading itself with bentonite and water, and then being mixed in a predetermined amount according to the purpose. Form into a size and shape (granular, capsule-like, spherical, etc.) and fire (dry), or fire itself to form a predetermined size and shape to give a water-floating sintered body. To manufacture.

In the production of the porous sintered body of the present invention, the above dust fine particles are first mixed with water and kneaded to have a predetermined size and shape (granular, capsule-like, spherical, etc.) according to the purpose.
Mold into Water is added in the required amount of fine particles capable of maintaining a predetermined shape. The molded product is preferably dried in an electric furnace, a heavy oil furnace, etc., preferably 500 from the viewpoint of strength and destructiveness after being dried naturally or forcedly dried by heat.
˜1100 ° C., particularly preferably 600 to 900 ° C. for a predetermined time (for example, 50 to 70 minutes). A part of the formed product is melted by the firing to become a porous sintered body. The obtained sintered body usually has an air permeability of 25 to 200 and a porosity of 25 to 4
5%, compressive strength (breaking strength) 5 to 10 kg fired at 600 ° C, 20k fired at 600 to 900 ° C
It is a porous sintered body having a high strength of g or more.

The water-buoyant porous sintered body of the present invention using the dust collected from the melting furnace for cast iron and the raw material for the sintered body having a bulk specific gravity of 0.5 or less can be produced in the same manner as described above. You can

Another porous sintered body of the present invention is formed by adhering a paste obtained by adding water to the dust particles and kneading the same to a sintered body having a desired property. Can be preferably dried by natural drying or forced drying and then calcined. In particular, a water-buoyant porous sintered body of the present invention is used by using a water-buoyant sintered body as the sintered body, adhering the paste to the molded body, molding, and preferably drying and firing. Since it can be produced, it floats on water, and is particularly effective for cleaning contaminants such as oil floating on the surface of water.

The water purification material of the present invention comprising the above-mentioned porous sintered body can be algae, pesticides (herbicides, etc.), sterilized by simply putting it in a water tank, pond, swamp, lake, river or the like and exposing it to sunlight. Organic substances such as agents, mineral oil and water-soluble resins, and inorganic substances such as fertilizers can be photolyzed to improve water quality, but further, water flow is generated or water is circulated to further improve the water purification material. By making it easy to contact, it is effective for water purification by adsorbing organic substances and inorganic substances. The amount of water purification agent used varies significantly depending on the quality of the water to be purified, but the higher the amount used, the higher the BOD (biochemical oxygen demand), COD (chemical oxygen demand), suspended solids, chromaticity, and turbidity. The degree etc. can be improved.

[0018]

The present invention will be described in more detail with reference to the following examples. In the examples and comparative examples, “%” means “% by weight” in principle. Example 1 Production of porous sintered body and its characteristics Dust collection dust of low frequency furnace for melting cast iron (particle size: 10 to 30 μm)
m, component: MgO 2.615%, Al ₂ O ₃ 0.1
33%, SiO ₂ 0.828%, P ₂ O ₅ 0.009
%, SO ₃ 0.296%, Cl 1.137%, K ₂
O 0.045%, CaO 0.048%, Cr ₂ O ₃
0.045%, MnO 0.264%, Fe ₂ O ₃
8.489%, ZnO 85.656%, PbO 0.
349%, Ac 0.086%) 1000 g, water was added at a ratio of 200 ml, and the mixture was kneaded uniformly with a kneader. Next, the kneaded product was extruded with a screw type extruder and molded with a granulator into a substantially spherical body having an average particle size of 1.0 to 1.5 cm. The molded product was dried at room temperature for a whole day and night, and further baked in an electric furnace at 900 ° C. for 60 minutes to produce the porous sintered body of the present invention. A micrograph (8 times enlarged photograph) of the particle structure (porous structure) of the obtained porous sintered body is shown in FIG.
2 shows an electron micrograph (EPMA, 70 × magnified photograph).

The characteristics of the obtained porous sintered body are shown below. Bulk specific gravity: 0.85 pH: 7 Air permeability: 150 Porosity: 45 (volume)% Compressive strength (breaking strength): 20 kg Moisture: 0.02%

Purification of water 8 liters of water taken from in-house water (mainly groundwater and industrial water) and 1000 g of the porous sintered body
Was placed in a 200 cm × 200 cm × 50 cm water tank, and a 15 W ultraviolet fluorescent lamp was irradiated from about 5 cm above the water surface for 24 hours at a water temperature of 10 to 25 ° C. The transparency of the water before and after the irradiation with the ultraviolet light was measured by the method of JIS-K0102, and was 15 cm and 100, respectively.
cm. The transparency after leaving the above water alone at a water temperature of 10 to 25 ° C. for 24 hours was 10 cm. In addition, the zinc elution amount in the water after UV irradiation is 0.03 m
g / liter.

Example 2 Production of Water Floatable Porous Sintered Body With respect to 1000 g of dust collected in the same low frequency furnace for melting cast iron as in Example 1, a bulk specific gravity of silica and alumina as main components was 0. 07-0.5, average particle size 37 μm-1.
6 mm foamed particles (Sila Sil Ltd. Sila
x) was added at a ratio of 1000 g and water at a ratio of 200 ml to form a substantially spherical body having an average particle diameter of 1.0 to 1.5 cm in the same manner as in Example 1. This molded product was dried at room temperature for a whole day and night, and further baked in an electric furnace at 850 ° C. for 60 minutes to produce the water-floating porous sintered body of the present invention. The microscopic photograph (8 times enlarged photograph) of the particle structure (porous structure) of the obtained water-floating porous sintered body is shown in FIG.
A, 280 times enlarged photograph) is shown in FIG.

The characteristics of the obtained water-floating porous sintered body are shown below. Bulk specific gravity: 0.60 pH: 7 Air permeability: 180 Porosity: 40 (volume)% Compressive strength (breaking strength): 15 kg Moisture: 0.02%

Purification of waste water containing cutting oil Water-soluble cutting oil (mineral oil 50 to 80%, fats and oils and fatty acids 0 to
30%, extreme pressure additive 0-30%, surfactant 15-35
%, Alkanolamine and inorganic alkali 0-5%, organic inhibitor 0-5%, preservative 0-2%, non-ferrous metal anticorrosive 0-1%, defoamer 0-1%, Castrol Co., Ltd. EP-690. ) Of 11.32 Brix% (weight% when sucrose is dissolved in water) and 8 liters of waste water and 150 g of the above water-floating porous sintered body are 200 cm × 200.
The sample was placed in a cm × 50 cm water tank, and exposed to sunlight at a water temperature of about 15 ° C. for 1 day and another 2 days (sunshine). The refractive index of the wastewater was measured 1 day and 3 days after sunlight irradiation, and the Brix% was calculated from the refractive index.
% And 1.67 Brix%. Further, the amount of zinc eluted in the waste water after irradiation with ultraviolet rays was 0.01 mg / liter.

Comparative Examples 1 and 2 Purification of Waste Water Containing Cutting Oil Water-soluble cutting oil (EP-690 manufactured by Castrol Co., Ltd.)
20 liters of the waste water containing 11.32 Brix% and 150 g of titanium oxide particles (3 mesh) or zinc oxide particles (3 mesh) are 200 cm × 200 cm × 50 cm.
, And exposed to sunlight at a water temperature of about 13 ° C. for 1 day and a further 2 days (sunshine). 1 day after solar irradiation and 3
The refractive index of the wastewater after the day was measured, and the Brix% was calculated from this, and the results are shown in Table 1 below.

[0025]

[Table 1]

Example 3 Production of Water Floatable Porous Sintered Body Water was added at a rate of 200 ml to 1000 g of dust collecting dust of the same low frequency furnace for melting cast iron as in Example 1.
A paste was prepared by uniformly kneading with a kneader. On the other hand, the bulk specific gravity of silica and alumina is 0.07
To 0.5 g, and foamed particles having an average particle diameter of 37 μm to 1.6 mm (Silux, manufactured by Shirasu Co., Ltd.) to 1000 g, 200 ml of water and 100 g of bentonite were added at a ratio and kneaded uniformly with a kneader. Then, the kneaded product was extruded by a screw type extruder and molded into a substantially spherical body having an average particle size of about 1.0 cm by a granulator. The molded product was dried at room temperature for a whole day and night, and further fired at 1000 ° C. for 60 minutes in an electric furnace to produce a spherical water-floating sintered body having a bulk specific gravity of about 0.55. For 1000 g of this water floatable sintered body,
The paste was mixed at a ratio of 100 g to adhere the paste to the surface of the spherical body, dried at room temperature for a whole day and night, and further baked in an electric furnace at 900 ° C. for 60 minutes to produce a water-floating porous sintered body. did.

The characteristics of the obtained water-floating porous sintered body are shown below. Bulk specific gravity: 0.60 pH: 7 Air permeability: 140 Porosity: 40 (volume)% Compressive strength (breaking strength): 15 kg Moisture: 0.02%

Purification of wastewater containing phenolic resin 3 liters of wastewater of pH 12 containing 1.2% as a solid content of an alkaline phenolic resin used for hardening the sand mold for casting, and the above water-floating porous sintered body 150.
0 g was placed in a transparent cylinder made of acrylic resin having a diameter of 10 cm and a height of 50 cm, and exposed to sunlight at daytime and sunlight at 15 ° C for 5 days and an ultraviolet fluorescent lamp of 15 W at night for about 5 cm. When pH of the wastewater after irradiation for 5 days and gas chromatography analysis of the phenol resin and formaldehyde were carried out, the pH was 7.51 and the residual amounts of the phenol resin and formaldehyde were both 0.0002% or less. Further, the amount of zinc eluted in the waste water after irradiation with ultraviolet rays was 0.01 mg / liter.

[0029]

As described above, according to the present invention, pores are evenly distributed, strength and air permeability are excellent, and a sintered body capable of adsorbing and photodecomposing an organic substance and the like for a long period of time, and a water quality comprising the same. It has become possible to provide purification materials. Further, in the present invention, since a mixture dust such as an inorganic oxide containing at least zinc oxide generated from a furnace that melts a cast iron raw material is used, it is possible to reduce the amount of dust to be disposed of, and to reduce the environment. It can also contribute to conservation. Further, the porous sintered body of the present invention has an extremely low elution amount of zinc in water, and therefore sufficiently satisfies the legal water quality standard (zinc elution amount of 1.0 mg or less).

[Brief description of drawings]

FIG. 1 is a micrograph of a particle structure of a porous sintered body according to an example of the present invention.

FIG. 2 is an electron micrograph of a particle structure of a porous sintered body according to an example of the present invention.

FIG. 3 is a micrograph of a particle structure of a water-buoyant porous sintered body according to an example of the present invention.

FIG. 4 is an electron micrograph showing a particle structure of a water-floating porous sintered body according to an example of the present invention.

Claims (6)

[Claims] 1. A porous sintered body obtained by adding water to a mixture dust of an inorganic oxide containing at least zinc oxide, which has been evaporated and dust-collected from a melting furnace for cast iron, and kneaded the mixture to form a molded product. . 2. A raw material for forming a sintered body having a bulk specific gravity of 0.5 or less and water are added to a mixture dust of an inorganic oxide containing at least zinc oxide, which is evaporated and collected from a melting furnace for cast iron, and kneaded and molded. A water-floating porous sintered body obtained by firing a molded product. 3. A molded product obtained by adhering to a sintered body a paste prepared by admixing water with a mixture dust of a mixture of inorganic oxides containing at least zinc oxide, which is evaporated and collected from a melting furnace for cast iron. A porous sintered body obtained by firing. 4. A paste obtained by adding water to a mixture dust of a mixture of inorganic oxides containing at least zinc oxide, which has been evaporated and dust-collected from a melting furnace for cast iron, is attached to a water-buoyant sintered body to be molded. A water-floating porous sintered body obtained by firing the molded product. 5. The porous sintered body according to any one of claims 1 to 4, wherein the molded body is dried before firing. 6. A water purification material comprising the porous sintered body according to claim 1, 2, 3, 4 or 5.