JPH11314073A - Process of turning incineration ash harmless - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process of turning incineration ash harmless for shortening the heat treatment time for incineration ash and reducing the treatment cost thereof. SOLUTION: An incineration heating device 2 using microwaves, preferably using a microwave oven and infrared rays is used for heating incineration ash. It is preferable to mix active carbon in the incineration ash before heating the incineration ash. The mixing ratio of active carbon in incineration ash (including unburnt carbon contained in incineration ash before mixing) is preferably set as 5-20 wt.%. The heat of incineration ash can be carried out under the oxygen shortage atmosphere. The heating condition of incineration ash is set preferably at 250-600 deg.C heating temperature for one minute to 24 hours.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detoxifying fly ash and incinerated ash such as cinders discharged from dust collectors such as bag filters and electric precipitators.

[0002]

2. Description of the Related Art Conventionally, heat treatment has been performed as a method of detoxifying harmful organic compounds such as dioxin contained in incinerated ash such as fly ash and cinder. This is a method in which harmful organic compounds such as dioxin in the incinerated ash are decomposed by heating the incinerated ash to 300 ° C. or more. In this method, the incineration ash is generally heated by external heating using infrared rays. Therefore, in addition to incineration ash, heat is taken away by the equipment and the surrounding atmosphere, and it is necessary to take sufficient time for heat treatment of the incineration ash in order to uniformly heat the incineration ash, and to give sufficient heat to the incineration ash And these have caused high processing costs.

[0003]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a method for detoxifying incinerated ash which can reduce the time required for heat treatment of incinerated ash and reduce the cost of processing.

[0004]

The method for detoxifying incinerated ash according to the present invention is a method characterized by using microwaves, preferably microwaves and infrared rays, for heating incinerated ash.

[0005] Before heating the incinerated ash, it is preferable to mix activated carbon into the incinerated ash.

The mixing ratio of activated carbon (including unburned carbon contained in the incinerated ash before mixing) in the incinerated ash is preferably 5
-20% by weight.

[0007] It is also possible to heat the incinerated ash in an oxygen-deficient atmosphere.

The heating condition of the incinerated ash is a temperature of 250 to 600 ° C.
And the time is preferably 1 minute to 24 hours.

The microwave heats the incineration ash internally. Compared to the external heating of the incineration ash by infrared rays, the heat is less likely to be taken away by the apparatus and the peripheral atmosphere other than the incineration ash.
For this reason, the residence time and heat supply amount for uniformly heating the entire incineration ash are smaller when using internal heating by microwaves than by external heating by infrared rays, and the heat treatment time and processing cost are reduced. it can.

[0010] By mixing activated carbon into the incineration ash, the rate of temperature rise inside the incineration ash by microwaves increases, and the mixing rate of the activated carbon and the temperature rising rate are in a proportional relationship (see Table 1). When a large amount of unburned carbon is present in the incineration ash, or when activated carbon is blown in the upstream of the dust collector, the amount of activated carbon mixed in the upstream of the incineration ash heating device may be small.

[0011] Further, when external heating by infrared rays is also used when performing internal heating by the microwave, internal heating and external heating are simultaneously performed on the incinerated ash, whereby the entire incinerated ash is quickly heated to a predetermined temperature. In addition, the heat treatment time can be reduced.

[0012]

FIG. 1 shows an embodiment of an incineration ash heating apparatus.

Fly ash is discharged from the bag filter (1) of the exhaust gas treatment device, and cinder is added to the fly ash as required. Next, the fly ash is mixed with a required amount of activated carbon. Fly ash containing activated carbon is then passed through a microwave generator
(3) and incineration ash heating device with infrared generator (4) (2)
Is heated internally by microwaves and externally heated by an infrared generator (4), and visually observed that the temperature has risen to a red-hot state of about 600 ° C. Is discharged out of the apparatus.

Table 1 shows the relationship between the mixing ratio of activated carbon and the time required for fly ash to reach 600 ° C.

[0015]

[Table 1]

[0016]

According to the microwave heating, the residence time and the heat supply amount for uniformly heating the entire incineration ash can be reduced, and the heat treatment time and the treatment cost can be reduced.

By mixing activated carbon into the incinerated ash, the temperature rise rate inside the incinerated ash by microwaves is increased, and the above effect is further enhanced.

By using both microwave heating and infrared heating, internal heating and external heating are simultaneously performed on the incinerated ash, whereby the entire incinerated ash is quickly heated to a predetermined temperature, thereby shortening the heat treatment time. It is possible.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing an example.

[Explanation of symbols]

 1: bag filter 2: incineration ash heating device 3: microwave generator 4: infrared generator

Claims (6)

[Claims] 1. A method for detoxifying incinerated ash, which comprises using microwaves for heating the incinerated ash. 2. A method for detoxifying incinerated ash, comprising using microwaves and infrared rays together to heat the incinerated ash. 3. A method for detoxifying incinerated ash, wherein activated carbon is mixed into the incinerated ash before heating the incinerated ash. 4. The method for detoxifying incinerated ash according to claim 3, wherein the mixing ratio of activated carbon in the incinerated ash is 5 to 20% by weight. 5. The method for detoxifying incinerated ash according to claim 1, wherein the heating of the incinerated ash is performed in an oxygen-deficient atmosphere. 6. The method for detoxifying incineration ash according to claim 1, wherein the heating of the incineration ash is performed at 250 to 600 ° C. for 1 minute to 24 hours.