JP3254589B2 - Method and apparatus for producing artificial lightweight aggregate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing an artificial lightweight aggregate for lightweight and high strength among aggregates for cement concrete and concrete products.

[0002]

2. Description of the Related Art Artificial lightweight aggregates used for concrete building materials include those obtained by sintering and foaming the incinerated ash of coal ash and other industrial wastes, and sintering foamed shale and volcanic glassy minerals to reduce the specific gravity. Are used. Since artificial lightweight aggregates are lighter than natural aggregates, concrete and concrete building materials using the aggregates are lighter, which is advantageous in workability and can reduce the weight of high-rise buildings. It is very advantageous also in terms of.

However, as shown in Table 1, artificial lightweight aggregates are inferior to natural aggregates in strength and durability.

[0004]

[Table 1]

[0005] Therefore, the artificial lightweight aggregate shown in Table 1 above was improved so that uniform closed cells were formed therein, and
By vitrifying the surface of the artificial lightweight aggregate, a product having improved weakness of the conventional artificial lightweight aggregate, that is, an improved artificial lightweight aggregate has been manufactured.

[0006] In order to produce such general artificial lightweight aggregates and improved artificial lightweight aggregates, the raw materials are pulverized by a dry or wet method, and granulated by adding a foaming agent or a binder as necessary. And
A method of firing with a rotary kiln is used.

[0007] When baking artificial lightweight aggregate in a rotary kiln, the baking temperature of raw material of aggregate (also referred to as input material)
The firing time must be controlled according to the properties of the input raw materials. The reason is as follows. (1)
If the firing temperature of the input raw material in the rotary kiln is low or the firing time is short, the strength and durability are reduced in terms of quality. (2) If the firing temperature is too high, the input raw materials are melted and adhere to the inner wall of the rotary kiln, or the input raw materials adhere to each other to form a large lump. (3) If the input raw material residence time in the rotary kiln is too long, the foam type is over-foamed and the strength is reduced.

On the other hand, the size of the aggregate must be from 20 mm to 1 mm or less. However, if these different sizes are fired simultaneously, it is not preferable in terms of quality. Therefore, the raw materials are fired separately for each size width. However, as the diameter of the rotary kiln increases, it becomes more difficult to fire the fine aggregate raw materials.

[0009] More specifically, Table 2 shows the results of experiments on the diameter of a rotary kiln and the minimum raw material size during a stable operation of 10 hours or more.
The result is obtained.

[0010]

[Table 2]

[0011] The reason is that as the diameter of the kiln increases, the rolling of the fine aggregate raw material decreases 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 is melted into a large lump. for that reason,
Only small-diameter rotary kilns can be used for artificial lightweight aggregate firing of fine aggregates, which makes mass production as an industrial product difficult.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to enable fine aggregate raw materials to be completely fired without using a rotary kiln. Another purpose is to make effective use of the thermal energy of the rotary kiln.

[0013]

SUMMARY OF THE INVENTION The present invention provides a rotary kiln provided with a means for supplying a raw material of coarse aggregate;
An airflow furnace communicating with the kiln and having a means for supplying fine aggregate raw material; and an apparatus for manufacturing an artificial lightweight aggregate, wherein the above object is achieved.

[0014]

The raw material of coarse aggregate and the raw material of fine bone are formed by granulation, and the raw material of coarse aggregate is fired by a rotary kiln.
By firing the raw material for fine aggregate 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.
Add the additives such as a foaming agent and a binder as needed to granulate the coarse aggregate raw material (coarse aggregate raw pellet) A and the fine aggregate raw material (fine aggregate raw pellet) B. . This coarse aggregate raw pellet A is formed to a particle size of 1.5 to 3.0 mm, for example.
Further, the fine aggregate raw pellet B has, for example, a particle size of 1.5 to 3.
It is formed to 0 mm.

The coarse aggregate raw pellets A are supplied to the coarse aggregate raw material weighing machine 1 and then supplied to the rotary kiln 17 in predetermined amounts. At this time, the temperature inside the rotary kiln 17 is high due to the burner 6 in the kiln.
The temperature of the inside of the kiln 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 pellets A supplied into the kiln 17
After being fired while rotating for a predetermined time, it is supplied to the cooler 18 and cooled to become the coarse aggregate product 4.

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

The pellets B supplied into the gas flow furnace 16 are raised in the furnace while being fired by heat exchange and collected by the cyclone 15. Thereafter, the pellets B are conveyed from the outlet of the cyclone 15 to the cooler 19 and cooled to become fine aggregate products.

The exhaust gas C is exhausted by the fan 11 into the exhaust duct 2.
, And is discharged to the atmosphere from the chimney 9 after being dust-removed.

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

The second embodiment is used, for example, when crushing a non-standard calcined product and regenerating it into fine aggregate. In this case, the crushed and crushed burned crushed product S is supplied to the coarse aggregate crushed raw material weighing machine 3, and the crushed product S is baked by the calcination gas in the gas flow furnace 16 and the calcination gas of the burner 8. .

The reason why the fired and crushed product S is refired as described above is as follows. In other words, when the fired aggregate is crushed into a fired crushed product for fine aggregate, the shape is square, so that when mixed with cement, the fluidity is reduced and the foam type has a large water absorption. This causes a problem. In order to solve this problem, the crushed product is fired, and the surface thereof is heated and melted to perform a so-called surface treatment.

FIG. 4 is a view showing a third embodiment. The difference from the first embodiment is that a preheating means such as a dryer 30 is provided between the coarse aggregate raw material weighing machine 1 and the rotary kiln 17.
After the coarse aggregate raw pellets A are dried in advance, they are sent to the rotary kiln 17. This embodiment is effective when the coarse aggregate raw pellet A contains a large amount of water.

[0025]

According to the present invention, the raw material of coarse aggregate is separately fired in a rotary kiln, and the raw material of fine aggregate is separately fired in a gas stream furnace. Therefore, unlike the conventional example, the fine aggregate raw material can be completely fired without using a rotary kiln, and the aggregate can be produced in a series of steps as required.

[0026] Further, the firing gas of the rotary kiln is supplied into the gas flow furnace and used for firing the raw material of fine aggregate.
Effective heat utilization can be achieved and it is economical.

[Brief description of the 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.

FIG. 3 is an enlarged cross-sectional view taken along the line III-III of FIG. 2;

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

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Satoru Fujii 6276 Onoda, Onoda-shi, Yamaguchi Pref. Onoda Cement Co., Ltd. Production Engineering Laboratory (56) References JP-A-49-48720 (JP, A) JP-A-48-14914 (JP, A) JP-A-59-13660 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 14/02 C04B 20/04-20/06

Claims (5)

(57) [Claims] A rotary kiln provided with a means for supplying a raw material of coarse aggregate; and an airflow furnace in communication with the rotary kiln and provided with a means for supplying a raw material of fine aggregate; An apparatus for producing an artificial lightweight aggregate, 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 a raw material of 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 means for supplying a coarse aggregate crushed product. 4. A step of forming a raw material of coarse aggregate and a raw material of fine aggregate; a step of supplying the raw material of coarse aggregate to a rotary kiln and firing; And firing the mixture in a gas flow furnace communicating with the rotary kiln. 5. The method for producing an artificial lightweight aggregate according to claim 4, wherein the coarse aggregate crushed product is supplied to an airflow furnace.