JP2518738B2 - Manufacturing method of fine-grained ceramic balun by continuous air flow firing furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a fine-grained ceramic balloon by a continuous airflow firing furnace using a natural glassy mineral and / or an artificial glassy material as a raw material.

[Conventional technology]

It has been conventionally practiced to use a conventional natural glassy mineral and / or an artificial glassy material as a raw material, grind it, granulate it into suitable particles, and fire and foam it to produce a lightweight foam. As a conventional firing method, a method of firing using a rotary kiln has been widely adopted.

[Problems to be Solved by the Invention]

However, in the case of firing and foaming fine particles of 1 mm or less with the rotary kiln, the thermal efficiency is low, the vitreous material is softened in the process of foaming, and thereby mutual fine particles are attached,
Since there is a problem that the particles cannot be fired and foamed, a large amount of anti-fusion agent is added, and there is a problem that the yield is poor.

On the other hand, the air flow type firing furnace has been conventionally used for firing sewage sludge, but since the firing temperature is as high as 1100 to 1150 ° C and the air flow rate is high, there is a problem that fine particles of 1 mm or less cannot be fired. Was.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a fine-grain ceramic balloon in a continuous airflow firing furnace which is a fine grain of 1 mm or less and which can efficiently perform firing and foaming.

[Means for solving the problem]

According to the first object of the present invention, a method for producing a fine-grained ceramic balloon by a continuous airflow firing furnace according to claim 1, wherein a finely pulverized natural glassy mineral and / or artificial glassy material is placed in a firing furnace and foamed and fired. In the method for producing a granular ceramic balloon, the firing furnace is a continuous airflow firing furnace, and the raw material is granulated in advance to a predetermined particle size before being put into the continuous airflow firing furnace, and the granulated product is a high melting point fine powder. It is configured by coating in advance.

Further, the method for producing a fine-grained ceramic balloon by the continuous airflow firing furnace according to claim 2 is the method according to claim 1, wherein the high melting point fine powder is kaori and / or alumina having a particle size of 20 μm or less, and The input amount is 5 to 20% of the granulated product.

A method for producing a fine-grained ceramic balloon by a continuous airflow firing furnace according to claim 3 is the method according to claim 1 or 2, wherein the continuous airflow firing furnace has a vertical airflow with an enlarged diameter. It is a firing furnace, and is configured so that the rising velocity of hot air in the furnace is 0.5 m / sec or less in the maximum cross-sectional area portion in the furnace.

[Action]

In the method for producing a fine-grained ceramic balloon by the continuous airflow firing furnace according to any one of claims 1 to 3, the finely pulverized raw material is once granulated to form fine grains having uniform grain size, and the high melting point fine grain Since the powder is coated in advance, even if the vitreous material is softened during the firing process, it is possible to prevent the adhering of adjacent fine particles.

And, particularly in the method for producing a fine-grained ceramic balloon by the continuous airflow firing furnace according to claim 3, since the hot air rising speed of the vertical airflow firing furnace is 0.5 m / sec or less in the firing portion, 0.1 to 1 mm. It is possible to perform firing without scattering fine particles.

〔Example〕

Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

Here, FIG. 1 is a partially cutaway perspective view of a continuous airflow firing furnace used in an embodiment of the present invention, and FIG. 2 is a sectional view thereof.

First, the continuous airflow firing furnace used in the method of one embodiment of the present invention will be described. As shown in FIG. 1, the continuous airflow firing furnace 10 is equipped with burners 11 to 13 in the lower part and an exhaust port 14 in the upper part. And a vertical airflow furnace having a raw material charging port 15, and umbrella-shaped peripheral wall jet plates 16 and 17 in the middle. Then, the continuous airflow firing furnace 10 is expanded to the upper part to slow down the wind speed that pushes up the raw material in the upper part, so that the raw material does not fly from the exhaust port, the wind speed in the upper combustion chamber becomes 0.5 m / sec or less. So that it controls burners 11-13. Then, a rod 18 is provided on the top of the peripheral wall jet plate 16 on the upper side, and the gap between the upper side and the side wall is adjusted by an adjusting device (spring in this example) 19 on the upper side, so that the jet velocity can be controlled. There is.

Therefore, the raw material charged from the upper raw material charging port 15 is
It is heated by the jet flow blown up from around the peripheral wall jet plate 16, gradually falls to the lower part, and is also heated by the hot air blown up from around the peripheral wall jet plate 17 at the lower part, and further 85 at the lower part.
It is exposed to an atmosphere of 0 to 950 ° C., foams, gradually drops, and is discharged from the product discharge port 20 at the bottom. Since the foaming time varies depending on the particle size of the raw material, the residence time of the charged raw material is controlled to be about 30 seconds to 3 minutes by controlling the exhaust fan 21.

Next, an example in which Shirasu, which is an example of a natural glassy mineral, is used as a raw material will be described below.
First, Table 1 shows the components of Shirasu, which is an example of the raw material natural glassy mineral, and Table 2 shows the particle size distribution of the Shirasu used.

In Table 1, Ig · loss is mainly composed of crystal water.

If the raw material of the above-mentioned shirasu contains large particles, it will hinder the subsequent processing, so fine powder of 44 μm or less is used as a raw material through a sieve.

Next, put this fine powder of shirasu into an oscillating type Mississor (trade name, Omnimixer) with a stirring blade inside and a flexible material on the bottom surface, and add an aqueous sodium hydroxide solution, which is an example of a melting point depressant. To do. This sodium hydroxide aqueous solution contains 9 to 111 of fine powder of Shirasu, with the amount of pure NaOH added outside
It is added in the range of weight%. The amount of water should be such that the Shirasu fine powder is appropriately moistened.

As a result, fine granules having various particle sizes were produced. After that, when the granulated product was dried and sieved, the particle size distribution was as shown in Table 3.

If the product having a particle size of 1.0 mm or more is foamed and fired as it is, the product particle size becomes large, so the product is once crushed by a crusher to reduce the particle size and then sieved again. Then, those having a particle size of 0.1 mm or less are reduced again as a raw material.

Therefore, the crushed fine particles produced through the above steps are mixed with the granulated fine particles and sieved by a gyro shifter.

After that, fine particles having a required particle size are selected, and kaolin, alumina, etc., which are examples of high melting point fine powder, are applied to the fine particles.
This operation is performed by the above-mentioned oscillating mixer.

When high-melting point fine powder of kaolin having a particle size of 20 μm or less is used, 15 to 25% by weight (preferably 20% by weight) of the granulated fine particles is used.
It was confirmed that when alumina having a particle size of 1 μm or less is used, even if it is within 10% of the above fine particles, it is sufficiently effective.

Next, as shown in FIG. 2, these fine particles are gradually charged from the raw material charging port 15 and guided into the continuous air flow firing furnace 10 to be foamed, but the temperature inside the furnace is lower burners 11 and 12. ,13
850-950 ℃ at all times by adjusting the combustion amount and exhaust fan 21
Is adjusted so that the temperature of the firing zone 22 is maintained. As a result, the vitreous material inside the fine particles is softened, and the fine particles of Shirasu are foamed to increase the diameter by about 20%, whereby fine-grained ceramic balloons are manufactured.

The properties of the ceramic balloon thus manufactured are shown in Table 4.

Here, the water absorption rate is measured by the water absorption rate test method of JIS A1109 fine aggregate, and the strength means an average crushing strength of 20 points using a Kiya type hardness meter.

In the above examples, Shirasu was used as the natural glassy mineral, but the present invention is also applicable to anti-firestone, pearlite, volcanic rhyolite and the like.

Next, artificial glassy material crushed to 0.44 μm or less is used as a raw material, and about 11% of the above raw material is sodium hydroxide aqueous solution with sodium hydroxide pure content, and calcium carbonate is About 3% of the raw material was mixed, sufficiently stirred, and the same treatment as in the above example was carried out using the above oscillating mixer to produce a ceramic balloon. The properties are shown in Table 5.

[Effect of the Invention] In the method for producing a fine-grain ceramic balloon by the continuous airflow firing furnace according to the present invention, as is clear from the above description, the raw material is granulated and produced, and the dried granulation has a high melting point. Since fine powder is applied and fired after that, even fine particles made of natural glassy mineral or artificial glassy material of 1 mm or less, which was difficult to burn continuously in the past,
It became possible to continuously perform firing and foaming without any trouble.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a continuous airflow firing furnace used in one embodiment of the present invention, and FIG. 2 is a sectional view of the same. [Explanation of Codes] 10 …… Continuous air flow firing furnace, 11 to 13 …… Burner, 14 …… Exhaust port, 15 …… Raw material input port, 16,17 …… Peripheral wall jet plate, 18…
… Rod, 19 …… Adjustment device, 20 …… Product outlet, 21 ……
Exhaust fan, 22 ... Baking zone

Claims (3)

(57) [Claims] 1. A method for producing a fine-grained ceramic balloon in which finely pulverized natural glassy mineral and / or artificial glassy material is placed in a firing furnace and foamed and fired, wherein the firing furnace is a continuous airflow firing furnace, and Manufacture of fine-grained ceramic balloons in a continuous-flow firing furnace, characterized in that the raw material is granulated in advance to a predetermined particle size before being put into the continuous-flow firing furnace, and the granulated material is previously coated with high melting point fine powder. Method. 2. The ceramic according to claim 1, wherein the high melting point fine powder is kaolin and / or alumina having a particle size of 20 μm or less, and the amount thereof is 5 to 20% of the granulated product. Method of manufacturing balloon. 3. The vertical airflow firing furnace in which the continuous airflow firing furnace is expanded in diameter at the upper portion, and the hot air rising speed in the furnace is 0.5 m / sec or less in the maximum cross-sectional area portion in the furnace. Item 2. A method for producing a fine-grained ceramic balloon by the continuous airflow firing furnace according to Item 2 or Item 2.