JPH06135753A - Production of artificial lightweight aggregate and method therefor - Google Patents

Abstract

PURPOSE:To completely fire a fine aggregate raw material without using a rotary kiln and to effectively utilize the heat energy of the rotary kiln. CONSTITUTION:A rotary kiln 17 provided with a supply means 1 for a coarse aggregate raw material A and an air flow furnace 16 communicating with the rotary kiln 17 and provided with a supply means 2 for a fine aggregate raw material B are provided.

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 artificial lightweight aggregate for lightweight and high strength of cement concrete and aggregate for concrete products, and an apparatus therefor.

[0002]

2. Description of the Related Art As an artificial lightweight aggregate used for concrete building materials, etc., one obtained by burning and foaming incineration ash of coal ash or other industrial waste, foaming shale and volcanic glassy minerals to reduce the specific gravity. Those that have been used are used. Since the artificial lightweight aggregate is lighter than the natural aggregate, the concrete and the concrete building material using the aggregate are lightweight, which is advantageous in workability and can reduce the weight of the high-rise building. It is also very advantageous in terms of.

However, as shown in Table 1, the artificial lightweight aggregate is inferior to the natural aggregate in strength and durability.

[0004]

[Table 1]

Therefore, the artificial lightweight aggregate shown in Table 1 above is improved so that homogeneous closed cells are formed inside the aggregate.
By vitrifying the surface of the artificial light-weight aggregate, an improved artificial light-weight aggregate in which the weak points of the conventional artificial light-weight aggregate are improved has been produced.

In order to produce such a general artificial lightweight aggregate or an improved artificial lightweight aggregate, the raw material is pulverized by a dry method or a wet method, and if necessary, a foaming agent or a binder is added to granulate. Then
A method of firing in a rotary kiln is used.

When the artificial lightweight aggregate is fired in the rotary kiln, the firing temperature of the raw material of the aggregate (also referred to as input raw material)
The firing time must be controlled according to the properties of the input raw material. The reason is as follows. (1)
If the firing temperature of the feed material in the rotary kiln is low or the firing time is short, the strength and durability will be deteriorated in terms of quality. (2) If the firing temperature is too high, the charged raw materials melt and adhere to the inner wall of the rotary kiln, or the charged raw materials adhere to each other to form a large mass. (3) If the residence time of the charged raw material in the rotary kiln is too long, a foam type material will be over-foamed and the strength will be reduced.

On the other hand, the aggregate size is required to be 20 mm to 1 mm or less. However, it is not preferable in terms of quality if these different sizes are fired at the same time. Therefore, the raw material is divided into a certain size and fired. However, as the diameter of the rotary kiln increases, it becomes difficult to fire the raw material for the fine aggregate.

Concretely, from the diameter of the rotary kiln and the minimum raw material size experiment for 10 hours or more of stable operation, Table 2
Are getting the results.

[0010]

[Table 2]

The reason for this is that as the diameter of the kiln increases, the raw material of the fine aggregate becomes less rolling in the radial direction of the kiln, and the raw materials flow as a group in the axial direction of the kiln. This is because the raw material continues to be heated and the raw material melts into a large lump. for that reason,
Only small-diameter rotary kilns can be used for artificial lightweight aggregate firing of fine aggregates, making mass production as industrial products difficult.

In view of the above circumstances, an object of the present invention is to make it possible to completely burn a raw material for fine aggregate without using a rotary kiln. Another purpose is to make effective use of the thermal energy of the rotary kiln.

[0013]

DISCLOSURE OF THE INVENTION The present invention provides a rotary kiln having means for supplying a raw material for coarse aggregate; and the rotary kiln.
An object of the present invention is to achieve the above object by an apparatus for producing an artificial lightweight aggregate, which is characterized by comprising: a gas flow furnace which is in communication with a kiln and which has a means for supplying a raw material for fine aggregate.

[0014]

[Operation] A raw material for coarse aggregate and a raw material for fine aggregate are formed by granulation, and the raw raw material for coarse aggregate is fired in a rotary kiln.
By firing the fine aggregate raw material in an airflow furnace, both raw materials are simultaneously and completely fired.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the accompanying drawings. Raw materials for artificial lightweight aggregates, for example, shale, volcanic glassy minerals, coal ash, etc. are crushed in a raw material process not shown,
A coarse aggregate raw material (coarse aggregate raw pellet) A and a fine aggregate raw material (fine aggregate raw pellet) B are granulated by adding additives such as a foaming agent and a binder as necessary. . This coarse aggregate raw pellet A is formed to have a particle size of 1.5 to 3.0 mm,
The fine aggregate raw pellets B have, for example, a particle size of 1.5 to 3.
It is formed to 0 mm.

The coarse aggregate raw pellets A are introduced into the coarse aggregate raw material weighing machine 1 and then supplied to the rotary kiln 17 by a predetermined amount. At this time, the temperature inside the rotary kiln 17 is high due to the burner 6 inside the kiln.
The temperature inside is controlled by a temperature controller (not shown), and the rotation speed of the kiln is controlled by a rotation speed controller (not shown). The residence time of the pellet A in the kiln is appropriately adjusted depending on the properties of the pellet A.

The pellet A fed into the kiln 17
After being baked while rotating for a predetermined time, the coarse aggregate product 4 is supplied to the cooler 18 and cooled.

On the other hand, the fine aggregate raw pellets B are introduced into the fine aggregate raw material weighing machine 2 and then are supplied to the airflow furnace 16 by a predetermined amount through the outlet duct 14 of the cyclone 15 and the cyclone 13. An airflow furnace burner 7 is provided in the lower part of the airflow furnace 16, and the lower part is connected in series to a rotary kiln 17. Therefore, the temperature inside the airflow furnace 16 is high due to the combustion gas of the burner 7 and the firing gas K from the rotary kiln 17.

The pellets B supplied into the airflow furnace 16 rise in the furnace while being fired by heat exchange and are collected by the cyclone 15. After that, the pellet B is conveyed from the outlet of the cyclone 15 to the cooler 19 and cooled to be a fine aggregate product.

The exhaust gas C is exhausted by the fan 11 to the exhaust duct 2
It is sent to the dust collector 10 via 0, where it is dusted and then discharged from the chimney 9 into the atmosphere.

The embodiment of the present invention is not limited to the above, but may be configured as follows, for example. FIGS. 2 and 3 are views showing a second embodiment. The difference from the first embodiment is that the coarse aggregate crushing raw material weighing machine 3 is provided in the upper part of the airflow furnace 16 and the upper burner 8 for the airflow furnace is provided. That is.

This second embodiment is used, for example, when crushing a nonstandard fired product to regenerate it into fine aggregate. In this case, the crushed and crushed burned crushed product S is supplied to the coarse aggregate crushing raw material weighing machine 3, and the crushed product S is burned by the burning gas in the airflow furnace 16 and the burning gas of the burner 8. .

The reason for re-baking the burned and crushed product S as described above is as follows. That is, when the burned aggregate is crushed into a burned crushed product for fine aggregate, its shape is angular, so the fluidity decreases when mixed with cement, and the foamed type has a high water absorption rate. There is a problem of becoming. In order to solve this problem, the so-called surface treatment is carried out by firing the crushed product and heating and melting the surface.

FIG. 4 is a diagram showing a third embodiment, which is different from the first embodiment in that a preheating means, for example, a dryer 30 is provided between the coarse aggregate raw material weighing machine 1 and the rotary kiln 17.
It is to feed the coarse aggregate raw pellet A into the rotary kiln 17 after previously drying. This example is effective when the coarse aggregate raw pellet A contains a large amount of water.

[0025]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, the coarse aggregate raw material is separately fired in the rotary kiln, and the fine aggregate raw material is separately fired in the airflow furnace. Therefore, unlike the conventional example, the fine aggregate raw material can be completely baked without using a rotary kiln, and those aggregates can be manufactured in a series of steps according to the required amount.

Further, since the firing gas of the rotary kiln is supplied into the airflow furnace and used for firing the fine aggregate raw material,
It is economical because it can effectively utilize heat.

[Brief description of drawings]

FIG. 1 is a flowchart showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a main part of a flowchart of a second embodiment of the present invention.

3 is an enlarged cross-sectional view taken along line III-III of FIG.

FIG. 4 is a diagram showing a main part of a flowchart of a third embodiment.

[Explanation of symbols] 1 coarse aggregate raw material weighing machine 2 fine aggregate raw material weighing machine 16 air flow furnace 17 rotary kiln A coarse aggregate raw material B fine aggregate raw material

Claims (5)

[Claims] 1. A rotary kiln provided with a means for supplying a raw material for coarse aggregate; and a gas flow furnace provided with a means for supplying a raw material for a fine aggregate, in communication with the rotary kiln; An apparatus for manufacturing an artificial lightweight aggregate characterized by comprising: 2. The apparatus for producing an artificial lightweight aggregate according to claim 1, wherein the rotary kiln is connected to a means for supplying raw material for coarse aggregate through a preheating means. 3. The apparatus for manufacturing an artificial lightweight aggregate according to claim 1, wherein the airflow furnace is provided with a means for supplying the coarse aggregate crushed product. 4. A step of forming a raw material for coarse aggregate and a raw material for fine aggregate; a step of supplying the raw material for coarse aggregate to a rotary kiln and firing; a raw material for fine aggregate. And a step of firing the mixture in an airflow furnace communicating with the rotary kiln. 5. The method for producing an artificial lightweight aggregate according to claim 4, wherein the crushed coarse aggregate product is supplied to the airflow furnace.