JP2000354841A - Solidification of incineration ash - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Decomposition of dioxin contained in ash and harmful volatile substances (chlorine, NOx, SOx, mercury, etc.) by subjecting incinerated ash to discharge plasma sintering while applying pressure
Reduction of concentration and heavy metals (Cr ⁶⁺ , Pb, Cu, Zn,
A method for solidifying incinerated ash that can prevent elution of Cd and Hg) and can separate and remove the same. SOLUTION: (1) After filling incinerated ash into a graphite mold (die), the pressure is increased to 2.94 × 10 ⁸ Pa to remove dioxins and volatile substances, and the plasma temperature is set to around 850 ° C. The temperature is raised at a stretch until the temperature is maintained at about 850 ° C. for about 5 minutes. (2) In order to convert the incinerated ash into slag with reduced sintering volume, the pressure was increased to 5.88 × 10 ⁸ Pa, and the temperature was further increased to 1,100 ° C., and sintering was performed for about 10 minutes under these conditions. I do. (3) The volume of the incinerated ash after the sintering process is reduced to about 1/10 or less, and it becomes a solidified molded slag from which toxic volatile substances have been removed. (4) A coating liquid having a waterproof property and a reinforcing effect is applied to the obtained solidified molded slag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidification molding method for final disposal of ash generated by incineration of waste such as municipal waste and radioactive waste. In particular, the present invention can reduce the body volume of incinerated ash to about 1/10 or less by subjecting the incinerated ash to discharge plasma incineration, and furthermore, has recently focused on decomposition of dioxin, NOx, The present invention relates to a method capable of reducing the concentration of toxic volatile substances such as SOx and mercury and contributing to protection and restoration of the global environment.

In particular, in the present invention, by controlling the discharge plasma sintering temperature, it becomes possible to select the containment or melting of heavy metals contained in the ash. Furthermore, the present invention relates to a method in which the process up to solidifying and molding the final disposal slag is simple, and a more secure solidified molded slag can be obtained by applying a coating treatment to the surface after solidifying and molding the slag. is there.

[0003]

2. Description of the Related Art Conventional refuse incineration ash treatment methods include a method in which incineration ash and a chemical are mixed and discarded in a landfill, which is a final disposal site, or a method in which cement and fly ash are mechanically kneaded and discarded. There is a method, and furthermore, a method of dissolving the ash at high temperature and disposing it as a molten slag and disposing it in a landfill, but in general the method of mixing and burning incinerated ash to make a stable chelate compound and disposing and disposing of it .

However, in some landfills, leaching of toxic component substances from incinerated ash has been problematic due to defects and inadequacy of water shielding facilities, leachate water collecting facilities, ash storage structures and the like. In addition, the method of separating and disposing of molten slag and heavy metal in the melt-solidification method has a complicated process itself and is economically problematic.

Further, conventionally, a method of directly disposing of incineration ash in an incineration ash landfill is generally used, and in some cases, toxic substance components leak from the incineration ash because of inadequate structure of the landfill. It is publicly announced that However, from the standpoint of each local government, the whole has not yet been clarified, and at present, the types and chemical analysis values of the leaked substance components from incinerated ash are kept secret. In some prefectures, concrete of incinerated ash is solidified. However, in order to solidify incinerated ash and concrete together, a large amount of concrete was required, and the weight reduction treatment was insufficient (up to 50 concrete). About 50 incineration ash). In addition, even with the conventional discharge plasma melting method, the steps required to obtain a stable slag for final disposal are complicated, and the equipment cost required for this is considerably high.

[0006]

SUMMARY OF THE INVENTION Therefore, in the present invention, in order to protect the environment and prevent pollution, it is an object of the present invention to obtain a solid molded product which is safer and easier to handle the final disposal slag.

[0007]

Therefore, in the present invention, the incineration ash is subjected to a discharge plasma incineration treatment,
A local high temperature of several thousand to 10,000 ° C. (discharge column = discharge plasma) can be instantaneously obtained in the incineration ash itself (the average temperature of the incineration ash is indicated by a temperature monitor detector). By this phenomenon, the decomposition of dioxins contained in the incineration ash, the reduction and removal of volatile toxic substances can be performed instantaneously, and the slag can be further processed into a reduced volume stable slag.

In the conventional discharge plasma melting method, no pressure is applied to the incinerated ash, and the method of raising the temperature is similar to indirect heating. Therefore, complicated processing steps and many facilities are required before incinerated ash is separated into stable slag with reduced volume.

In the present invention, the incineration ash is treated by adjusting the discharge plasma sintering treatment temperature to a melting point or lower, and the obtained solidified molded slag is coated with a water-resistant and reinforcing coating material, thereby providing a more secure. A volume-reduced solidified slag which is easy to handle is obtained. In the present invention, most of heavy metals in the obtained slag can be removed by treating the incinerated ash by adjusting the discharge plasma sintering treatment temperature to the melting point or higher.

Furthermore, by using the solidification method of the present invention for solidification molding of incineration ash treatment of combustible radioactive waste, volume reduction of incineration ash and enclosing of radionuclides in slag become easier.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) The incinerated ash to be solidified and formed is filled in a graphite die, and after evacuation, the pressure is increased to 2.94 × 10 ⁸ Pa. The plasma temperature is set at 850 to remove dioxins and volatiles.
The temperature is raised to about ℃ at a stretch. The temperature is kept at about 850 ° C. for about 5 minutes. In that case, the temperature of the incinerated ash local part was 1,0
It is over 00 ° C. Next, (2) in order to convert the incinerated ash into slag with reduced sintering volume, the pressure was increased to 5.88 × 10 ⁸ Pa, and the temperature was further increased to 1.1.
The temperature is raised to 00 ° C., and sintering is performed under these conditions for about 10 minutes. Further, in order to remove heavy metals in the incineration ash, the discharge plasma sintering temperature is maintained at 1,300 to 1,400 ° C. for about 15 minutes.

(3) The volume of the incinerated ash after sintering is about 1 /
The solidified molded slag is reduced in volume to 10 or less and toxic volatile substances are removed. (4) A coating liquid having a waterproof property and a reinforcing effect is applied to the obtained solidified molded slag. As the coating material, an epoxy resin such as an epoxy resin and polythiol is used.

The spark plasma sintering (SP) performed in the present invention
The principle of S) is that, as shown in FIG. 1, when a DC pulse voltage is repeatedly applied ON-OFF to a green compact sample, a local high temperature state (discharge plasma) of 1000 to 10000 ° C. is generated between the green compacts. Therefore, vaporization and melting phenomena are caused on the surface of the powder particles, and a constricted portion called a neck is formed at the contact portion between the particles, so that a welding state is obtained.

FIG. 2 is a schematic view of a discharge plasma sintering apparatus, in which an ON-OFF pulse voltage is applied to upper and lower electrodes, and a pressure of several to several tens tons is further applied to the upper and lower punches.
Inside the mold, a discharge plasma as shown in FIG. 1 is generated between the powders to be sintered and solidified, and the sintering and solidification are performed in a very short time.

[0015]

[Example] First step (removal of dioxins and volatile toxic substances contained in incinerated ash) Municipal garbage discharged from ordinary households is burned in an incinerator, and the residual incineration ash is discharged by plasma discharge. Sintering is performed.

The incinerated ash was charged into a graphite mold (die), evacuated, and then pressurized to 2.94 × 10 ⁸ Pa.
In order to remove dioxins and volatile substances, the temperature of the plasma was raised to about 850 ° C. and maintained at about 850 ° C. for about 5 minutes. At that time, the temperature of the local incineration ash became 1,000 ° C. or higher.

The concentrations of dioxin and volatile toxic substances, chlorine, NOx and SOx, are inconsistent with daily life (the concentration of dioxin is 0.005 ng
−TEQ / g, about 50 ppm for NOx and SOx) in a temperature range around 850 ° C.
It was necessary to hold for about a minute.

Second step (solidification and reduction of incineration ash) In order to reduce the volume of the incineration ash treated in the first step, the pressure is increased to 5.88 × 10 ⁸ pa in a graphite mold, and the sintering reaction is further performed. To raise the temperature, the temperature was raised to 1,100 ° C., and the temperature was maintained for about 10 minutes.

The results of volume reduction of the incinerated ash were as follows. Volume of incineration ash before spark plasma sintering: 75 cm ³ Volume of slag after spark plasma sintering: 7.0 cm ³
(Diameter: 3.0 cm x height: 1.0 cm, cylindrical pellet) In addition, the measurement result of the harmful metal concentration in the obtained volume-reduced solidified molded slag using an energy dispersive X-ray detector is detected. It was below the limit.

Third step (Surface treatment of solidified molded slag) A surface treatment material was applied to the surface of the solidified molded body to reduce the volume to about 1/10 or less and to waterproof and reinforce the solidified molded slag.

(Analytical value of incinerated ash-solidified molded slag) Dioxin can be reduced to a concentration that can be used in daily life by heating at about 900 ° C. according to other experimental data. At present, there is no regulation value of incineration ash set by the Ministry of Health and Welfare, and a reference value of 0.0 lng-TEQ / g is shown as a reference value. The sintering temperature solidified by the current spark plasma sintering method is 1,000-10,000 locally.
Since the temperature is about 0 ° C. and 1,100 ° C. at the temperature outside the sintered body, the dioxin concentration is further reduced from these general data values.

Regarding volatile toxic substances, the values of SOx and NOx are 3 in the discharge plasma sintering temperature range.
A pre-established value of 0 ppm or less is generally published.

In the analysis of inorganic substances, no harmful metals were detected as a result of measurement using an energy dispersive X-ray analyzer (EDX) and an X-ray diffractometer.

[0024]

According to the present invention, the volume of the solidified molded slag can be reduced by subjecting the incinerated ash to spark plasma sintering and subjecting the obtained solidified molded slag to a surface treatment having a waterproof and reinforcing effect. About 1 / compared to the volume of incinerated ash before treatment
Volume can be reduced to 10. Further, since the incineration ash can be treated at a high temperature, it is an effective incineration ash solidification method capable of reducing and removing dioxins and volatile toxic substances.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of spark plasma sintering.

FIG. 2 is a diagram showing a structure of a spark plasma sintering apparatus.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hisakichi Mitamura 2-4, Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki Pref. 2-4 Shirane F-term in the Japan Atomic Energy Research Institute Tokai Research Laboratory (reference) 2E191 BA12 BD01 BD11 BD18 4D004 AA36 AB03 AB07 AB10 CA03 CA14 CA30 CA44 CA45 CA50 DA02 DA06

Claims (2)

[Claims] An incineration ash is subjected to a discharge plasm incineration process while being pressurized from several tons to 20 tons to decompose dioxins contained in the ash and to remove harmful volatile substances (chlorine, NOx, SOx, mercury). Etc.) A method for solidifying incineration ash that can reduce the concentration, prevent elution of heavy metals (Cr ⁶⁺ , Pb, Cu, Zn, Cd, Hg), and separate and remove them. 2. By subjecting the incinerated ash to a discharge plasma sintering treatment, the incinerated ash can be solidified and molded at a lower temperature and in a shorter time, and the volume of the final ashes (1/10 or less of the original volume) can be reduced. ) Can be promoted, and the solidified molded body is waterproof,
A method for solidifying incinerated ash that is safer and easier to dispose and reuse slag by applying a coating material for surface protection, and that is suitable for global environmental protection and environmental restoration.