JPH0246535B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is a method for producing lightweight aggregate using incinerated ash as a raw material, which is suitable for reusing incinerated ash generated from coal-fired boilers, incinerators, etc. and commercializing it as lightweight aggregate. It is related to. (Prior Art) Conventionally, incineration ash such as coal incineration ash and garbage incineration ash has been used as
Efforts have been made to pelletize it using a pelletizer and then sinter it in a downward suction furnace and reuse it as lightweight aggregate.
Satisfies JIS lightweight aggregate standards and is commercially available.
It is preferable to have physical properties equal to or higher than those of ALA lightweight aggregate. However, in the conventional method, it is not easy to suppress the ignition loss of the obtained product to 1.0% or less, resulting in a decrease in product yield. On the other hand, in order to suppress the loss on ignition, efforts have been made to reduce the amount of combustibles added to the incinerated ash, increase the external heat capacity, and maintain the temperature inside the sintered layer at a high temperature by adjusting the operating conditions of the furnace. The former is unfavorable from the perspective of waste reuse as it significantly increases manufacturing costs, and the latter increases the heat retention effect within the layer, making clinker more likely to form in the middle and lower layers, which also reduces product yield. It was a result. (Problems to be solved by the invention) The present invention solves these conventional problems,
Not only does it meet the JIS lightweight aggregate standard, but it is also commercially available.
This was completed with the aim of creating a method for producing lightweight aggregate using incineration ash as a raw material, which can produce sintered products with physical properties equivalent to or higher than those of ALA lightweight aggregate at a high yield and at low cost. (Means for Solving the Problems) The present invention, which was made to solve the above problems, measures the amount of combustibles in the incineration ash, adds a combustible auxiliary agent as necessary, and calculates the total amount of combustibles. 4-8 (weight)
%, and further add iron oxide to 5~5% of the total weight.
It is characterized in that it is added at a rate of 15% and then sintered in a downward suction furnace. In the present invention, first, the amount of combustibles in the incineration ash is measured, and it is sufficient if the value is within the range of 4 to 8%, but if it is insufficient, the necessary amount of combustible aid is added to reduce the total amount of combustibles. It is adjusted to 4 to 8% (weight%, the same applies hereinafter). Here, pulverized coal is generally used as the combustible auxiliary agent, but it is not necessarily limited to this as long as the calorific value of the granules is about 600 kcal/Kg. Furthermore, the reason why the amount of combustible material is set at 4 to 8% is that if it is less than 4%, the internal calorific value will be insufficient, and in order to complete sintering, the external heat capacity must be increased, and the sintering time will also be extended. On the other hand, if it exceeds 8%, the amount of internal heat generation becomes excessive, making it difficult to control the temperature in the middle and lower layers, resulting in a high rate of clinker generation, which tends to lower the yield. Iron oxide is further added at a predetermined ratio to the incineration ash whose total combustible content has been adjusted to 4 to 8% in this way. Iron oxide is reduced in a reducing atmosphere in a downward suction furnace and releases oxygen, activating combustion inside the sintered body and making the sintered body foam, reducing its specific gravity and causing ignition. It has the effect of significantly reducing weight loss. The mixing ratio of iron oxide is preferably in the range of 5 to 15% based on the total weight,
If it is less than 5%, the effect is insufficient; on the other hand, if it is less than 15%
Even if the amount is added in excess of the above amount, the effect commensurate with the increase in the amount added will not be obtained, leading to an increase in manufacturing costs. The incinerated ash to which iron oxide has been added at a mixing ratio of 5 to 15% is then sintered in a downward suction furnace by a conventional method, and has excellent characteristic values as shown in the following examples. A lightweight aggregate will be obtained. (Example) As shown in the following table, the amount of combustible material is 2%, 4%, 6%.
%, 8% of 4 types of incineration ash with 0 to 4 pulverized coal
%, the total amount of combustibles falls within the range of the present invention of 4 to 8%, and those outside this range are adjusted, and further iron oxide is added at 0%, 5%, 10%, or 15% to lower it. Incinerated in a suction furnace. The incineration conditions were a loading height of 200 mm, a bedding thickness of 20 mm, an ignition time of 5 minutes, and a suction air volume of 5 Nm ³ /m ² ·min. When the total combustible content was 3%, sintering was impossible, and when the total combustible content was 10%, clinker was produced. For those with a total combustible content of 4 to 8%, residual carbon, loss on ignition, water absorption, absolute dry specific gravity, and crushing strength of the obtained sintered bodies were measured and recorded in the table. As is clear from this table, when the amount of iron oxide added is 0%, the residual carbon amount often exceeds 1%, and when the residual carbon exceeds 1%, the ignition loss also exceeds 1%. It can be seen that the probability of a defective product increases. However, if more than 5% iron oxide is added,
This means that the amount of residual carbon can be kept at 1% or less under any conditions.

【table】

[Table] (Effects of the Invention) As is clear from the above description, the present invention measures the amount of combustibles in the incineration ash and adds combustible aids as necessary to reduce the total amount of combustibles to 4 to 8%. At the same time, iron oxide, which releases oxygen as sintering progresses, is added at a predetermined ratio and then sintered to fully burn the incinerated ash using the chemical reaction of iron oxide, resulting in a strong We succeeded in obtaining a lightweight aggregate with excellent thermal loss and other physical properties. Therefore, according to the present invention, a lightweight aggregate that not only satisfies JIS standards but also has physical properties equivalent to or higher than commercially available ALA lightweight aggregates can be produced with a high yield, and the external heat capacity can be increased during sintering. Since there is no need to increase the temperature within the sintered layer depending on the operating conditions of the furnace, manufacturing costs can be reduced. Therefore, the present invention can significantly contribute to the development of industry as it solves the problems of the conventional method for producing lightweight aggregates using this type of incineration ash as a raw material.

Claims (1)

[Claims] 1. Measure the amount of combustibles in the incineration ash, add a combustible auxiliary agent as necessary, and reduce the total amount of combustibles to 4 to 8 (by weight).
%, and further add iron oxide to 5~5% of the total weight.
A method for producing lightweight aggregate using incinerated ash as a raw material, which is characterized by adding 15% of aggregate and sintering it in a downward suction furnace. 2. The method for producing lightweight aggregate using incinerated ash as a raw material according to claim 1, wherein the incinerated ash is coal ash and the combustible auxiliary agent is pulverized coal.