JPH1133517A - Method for solidifying incinerator ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently make incinerator ash of sewage sludge and municipal refuse usable by reliably enclosing harmful substances contained in the incinerator ash by adding water to incinerator ash of sewage sludge or incinerator ash of municipal refuse, stirring the resultant ash, and then adding a limestone type solidifying agent to the ash, and solidifying and molding the resultant mixture. SOLUTION: In the case incinerator ash of dewatered sludge cakes is treated, at first, water is added to the incinerator ash of sludge cakes and stirred in a stirring process 1 and the resultant ash is sent to a solidifying process 2. In the stirring process 21 of the solidifying process 2, a limestone type solidifying agent is added to the incinerator ash fluidized by adding water and then the resultant mixture is sent to a curing process 22. In the curing process 22, the sent mixture of evenly mixed incinerator ash, water, and the limestone type solidifying agent is cured for a prescribed period. During the curing period, water and the limestone type solidifying agent in the incinerator ash are reacted to produce slaked lime and the produced slaked lime and respective constituents of the incinerator ash are reacted and solidified to enclose harmful substances. After that, in a molding process 23, the solidified incinerator ash is molded corresponding to a purpose of a cement material to reuse the incinerator ash.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for solidifying ash obtained by incinerating sewage sludge or municipal waste, and more particularly to an effective use of incinerated ash.

[0002]

2. Description of the Related Art Sewage sludge is dewatered after passing through a concentration process for greatly reducing its volume and a digestion process for converting organic substances into stable inorganic substances, and the dewatered sludge cake is incinerated to greatly reduce the disposal amount. And then landfill for final disposal. Municipal garbage is also incinerated to convert organic matter to stable inorganic ash to reduce weight and render it harmless before reclaiming it as incineration ash from sewer sludge.

[0003]

As described above, landfill disposal of incinerated ash from sewage sludge and municipal garbage as described above makes it difficult to secure landfill sites and requires transportation costs to landfill sites. Would. In addition, even if harmful substances are converted to harmless substances by intermediate disposal, elements that themselves are harmful or difficult to detoxify, such as heavy metals, remain. There is a risk of spreading.

On the other hand, incinerated ash such as sewage sludge contains a large amount of silicic acid and the like, and there is a demand for effective use of the same.

An object of the present invention is to provide a method for solidifying incineration ash which satisfies such a demand and which can effectively utilize harmful substances contained in incineration ash of sewage sludge and municipal waste. is there.

[0006]

The incineration ash solidification method according to the present invention is characterized in that water is added to incineration ash of sewage sludge or incineration ash of municipal garbage, stirred, and then solidified by adding a lime-based solidifying agent. It is characterized by being molded.

A second incineration ash solidification method according to the present invention is characterized in that a cement or asphalt-based solidifying agent is added to incineration ash of sewage sludge or municipal waste and then solidified before molding.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The incineration ash solidification method of the present invention is a method of adding a certain amount of water to an incineration ash of sewage sludge, stirring and mixing, then adding a lime-based solidifying agent and stirring to obtain a homogeneous mixture. make. The homogeneous mixture is cured and solidified for a certain period of time, and after sealing harmful substances contained in the incinerated ash, the incinerated ash is reused by molding according to uses such as cement raw materials and roadbed materials.

When a cement-based solidifying agent or an asphalt-based solidifying agent is used, for example, a certain ratio of the cement-based solidifying agent or the asphalt-based solidifying agent is added to the incineration ash of sewage sludge and stirred to form a uniform mixture. After the uniform mixture is molded according to the application, it is cured for a certain period of time and the incinerated ash is reused.

[0010]

FIG. 1 is a process chart showing a processing procedure of a position embodiment of the present invention. As shown in the figure, for example, when treating the incinerated ash of a dewatered sludge cake, first, in a stirring step 1, a certain amount of water 6 is added to the incinerated ash 5 of the sludge cake, for example, the same amount of water as the incinerated ash is added. Stir and send to solidification step 2. In the agitation step 21 of the solidification step 2, the lime-based solidifying agent 7 of quicklime is added to the incinerated ash fluidized by adding water to the weight of the incinerated ash and water.
2020% is added, stirred and sent to the curing step 22. In the curing step 22, the uniform mixture of the incinerated ash, water and the lime-based solidifying agent is cured for a certain period. The curing period varies from several days to half a month, depending on the moisture content of the incinerated ash and other factors. During this curing period, the water in the incinerated ash reacts with the lime-based solidifying agent to produce slaked lime, which reacts with the slaked lime and the components in the incinerated ash to solidify and contain harmful substances. An example of the concentration of harmful substances eluted from the solidified incinerated ash is shown in the table below.

[0011]

[Table 1]

[0012] As shown in the above table, the amount of harmful substances eluted is far less than the concentration specified in the emission standard for harmful substances, and solidified incinerated ash should be used as cement raw material, roadbed material, backfill material or block. Can be. Therefore, in the molding step 23, the solidified incinerated ash is molded according to the application. In this way, the harmful substances contained in the incineration ash of the sewage sludge can be contained and the incineration ash can be used effectively.

In the above embodiment, the incineration ash of sewage sludge was solidified. However, the incineration ash of city garbage can also be solidified and reused.

In the above embodiment, the case where the lime-based solidifying agent 7 is used as the solidifying agent is described. However, the solidifying agent may be a cement-based solidifying agent or an asphalt-based solidifying agent. For example, a processing step when a cement-based solidifying agent is used will be described with reference to the process chart of FIG. For example, as a cement-based solidifying agent for incineration ash of sewage sludge, for example, soil cement a certain ratio to the weight of incineration ash
Add 40% and stir to make a homogeneous mixture, mold the homogeneous mixture according to the application, and cure for a certain period of time. As a result of examining the amount of harmful substances eluted from the incinerated ash solidified in this way, the concentration was much lower than the concentration specified in the emission standard for harmful substances.

[0015]

According to the present invention, as described above, a lime-based solidifying agent, a cement-based solidifying agent, or an asphalt-based solidifying agent is added to the incineration ash of sewerage sludge or municipal waste to solidify. The contained harmful substances can be reliably contained.

Therefore, the solidified incinerated ash can be effectively reused as a cement raw material, a roadbed material, a backfill material or a block, or can be packed into a sandbag and used for revetment. Therefore, it is not necessary to reclaim the incinerated ash. There is no need to secure a landfill site or transport costs to the landfill site, thereby reducing the cost of treating incinerated ash.

[Brief description of the drawings]

FIG. 1 is a process chart showing processing steps of an embodiment of the present invention.

FIG. 2 is a process chart showing processing steps of another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stirring process 2 Solidification process 21 Stirring process 22 Curing process 23 Molding process

Claims (2)

[Claims] 1. An incineration ash solidification method comprising adding water to sewage sludge or municipal incineration ash, stirring the mixture, adding a lime-based solidifying agent, solidifying and molding. 2. A method for solidifying incineration ash, characterized by adding a cement or asphalt-based solidifying agent to incineration ash of sewage sludge or municipal waste.