JPH07104439B2 - Melting vessel and method for melting miscellaneous waste using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a melting vessel for melting and processing miscellaneous wastes containing almost no organic matter such as incinerated ash and non-combustible miscellaneous solid wastes, particularly radioactive wastes, and a melting container therefor. More specifically, the present invention relates to a method for melting and treating miscellaneous wastes using a melting vessel formed by uniformly or non-uniformly impregnating silicon carbide or silicon carbide and graphite with metallic silicon. The present invention relates to a melting container that is improved and enables continuous processing for a long period of time, and a method for melting and processing miscellaneous waste using the melting container.

[Prior Art] Conventionally, various methods have been proposed as a method for melting and processing miscellaneous wastes, and for example, a melting and processing method using a microwave incineration melting apparatus, a high-frequency induction heating melting furnace, or the like is known. .

However, the method using a microwave melting apparatus mainly for treating incinerated ash has the drawbacks that discharge may occur due to mixing of combustible gas or metal during melting, operation control is difficult, and the processing capacity is small. A method using a high-frequency induction heating melting furnace is disclosed in, for example, JP-A-60-3870.
No. 0 and JP-A-60-38698. However, this method has a drawback in that it is difficult to obtain a temperature of 1100 ° C. or higher for a long time because a stainless steel is used as a heating element, and a large amount of a melting point depressant is required, so that the volume reducing property is deteriorated.

Further, JP-A-59-200999 by the present inventors discloses a high-frequency induction heating melting method using graphite as a heating element in a melting vessel. However, since graphite is used as a melting vessel in this method, a high temperature of around 1600 ° C can be obtained, but the outer wall surface is air, the inner wall surface is the melt, and the oxidation is the contact between the upper end of the melt and the melting container. The parts are heavily damaged and cannot withstand continuous use for a long time. Specifically, the one using this graphite has a practical operating time of about 3 to 10 hours, and at present, one capable of continuous treatment for about 50 to 100 hours is desired. In addition, in the usual measures against graphite consumption such as ceramic coating on the inner wall surface, the effect of contacting the slag substance causes the exfoliation and the effect disappears.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems.
It is an object of the present invention to provide a melting container that improves oxidation resistance and enables continuous processing for a long time, and a method for melting and processing miscellaneous waste using the melting container.

[Means and Actions for Solving the Problems] In order to achieve the above-mentioned object, the first aspect of the present invention is to perform miscellaneous processing of miscellaneous waste by using a high-frequency induction heating coil. A hollow melting container having a reservoir part and a take-out hole for taking out the molten miscellaneous waste in the lower part or the bottom part, and containing 10 to 20 wt.% Of silicon carbide or silicon carbide and graphite with respect to the total amount. The second aspect of the present invention is characterized by being formed by uniformly or non-uniformly impregnating metallic silicon, and the second aspect of the present invention is a reservoir portion into which miscellaneous waste is introduced for melting and processing the miscellaneous waste using a high-frequency induction heating coil. And melting the miscellaneous waste in a hollow melting container provided with an extraction hole for taking out the melted miscellaneous waste at the bottom or bottom, and appropriately closing the extraction hole using a stopper fitted to the extraction hole, Open and open the melt for continuous or intermittent treatment That in a melt processing method unclassified waste, the melting vessel, characterized in that formed silicon carbide or silicon carbide and graphite metallic silicon uniformly or non-uniformly impregnated.

The melting container of the present invention will be described below with reference to FIGS.

FIG. 1 is a side sectional view of a melting vessel according to the present invention, and FIG. 2 is a plan view thereof. In the figure, a melting container 1 is a hollow cylinder, and a reservoir 2 into which miscellaneous waste is put is formed inside, and a melt of miscellaneous waste is discharged at the center of the bottom of the reservoir. An ejection hole 3 for dropping is provided. Further, this take-out hole 3 is shaped to fit into a stopper described later.

In the melting container 1 of the present invention, silicon carbide is used as a main material and is impregnated with metallic silicon, or graphite and silicon carbide are used as main materials and metallic silicon is impregnated.

In the present invention, as the melting vessel 1 is thus used silicon carbide or silicon carbide and graphite impregnated with metallic silicon. The metallic silicon may be uniformly or non-uniformly impregnated. In this case, since silicon carbide itself does not become a suitable heating element in a low temperature region, when silicon carbide is impregnated with metal silicon, 10 to 20 wt.% Of metal silicon is used. When silicon carbide and graphite are impregnated with metal silicon, graphite is used. Is preferably contained in an amount of 30 wt.% Or more. Such a melting container 1 can be manufactured by the following manufacturing method. That is, a silicon carbide sintered body processed into a crucible shape or a silicon carbide sintered body and graphite are placed in a container filled with metallic silicon powder so that they do not come into contact with each other, and are placed in an inert gas such as argon gas. It is obtained by heat treatment in. The heat treatment conditions vary depending on the size, shape, etc. of the melting vessel to be produced, but when producing about 3 melting vessels, heat treatment may be performed at 1500 to 2000 ° C. for 3 to 5 hours. By processing in this way, the melting vessel 1 made of a material impregnated with metallic silicon is obtained.

As an application example of the present invention, as shown in FIG. 3, the melting vessel 1 itself is made by impregnating silicon carbide having good oxidation resistance with metallic silicon, and the stopper 4 is also made of the same material. Graphite 1b may be used as a heating element due to the adhesion between the extraction hole 3 and the stopper 4 at the tip thereof.

Next, the melt processing method of the present invention will be described with reference to FIG.

FIG. 4 is a diagram for explaining the melt processing method of the present invention.

In the figure, the miscellaneous waste 5 containing almost no organic matter such as incinerated ash and non-combustible miscellaneous solid waste is temporarily stored in the hopper 6, and the miscellaneous waste 5 appropriately passes through the supply pipe 7 Reservoir 2 of melting vessel 1 surrounded by induction heating furnace coil 8
Be thrown into. The outlet 2 is formed in the center of the bottom of the reservoir 2.
Is provided. The leading end of a stopper 4 that is raised and lowered by a stopper elevator 9 and the like is fitted into the extraction hole 3 to close the extraction hole 3. When a desired amount of miscellaneous waste 5 is filled in the reservoir 2 of the melting container 1, the melting container 1
Is heated by the high-frequency induction heating coil 8 and functions as a heating element, and the miscellaneous waste 5 is melted and solidified into a molten solidified material 10. When the miscellaneous waste 5 is completely melted, the stopper 4 is appropriately pulled up by the stopper lifter 9, the take-out hole 3 is opened, and the melt falls from the take-out hole 3 into the canister 11 by its own weight and is cooled and solidified. . When an appropriate amount of the melted substance falls into the canister 11, the stopper lifter 9 moves down the stopper 4, the stopper 4 tip fits into the extraction hole 3, the extraction hole 3 is closed again, and a new miscellaneous waste is fed from the supply pipe 7. 5
Is filled in the reservoir 2 of the melting container 1, and the canister 11 is repeatedly melted and solidified until it is filled with the molten and solidified material 10. Further, the waste gas is taken out from the waste gas pipe 12 and, if necessary, treated by the waste gas treatment system of the incinerator to remove radioactivity.

[Examples] Hereinafter, the present invention will be described based on Examples and Comparative Examples.

Example A silicon carbide sintered body processed into a crucible shape was placed in a container filled with metallic silicon powder under an argon gas atmosphere, and
Heat treatment was carried out at 00 ° C. for 4 hours to manufacture a melting container (capacity: about 3) made of silicon carbide impregnated with metallic silicon and having substantially the same shape as the melting container shown in FIG. The composition of the material of the obtained melting vessel was about 80 wt.% Silicon carbide and about 20 wt.% Metallic silicon.

Then, using this melting vessel and the melting processing apparatus substantially the same as the melting processing apparatus shown in FIG. 4, melting processing was performed under the following processing conditions.

In the obtained melting container, incinerator ash and powdered pearlite (heat insulating material) were mixed at a ratio of 1: 1 (weight ratio) to create simulated waste.
After charging 2.5 kg, continuously melting simulated waste at 1400 ° C,
The melt was supplied at a processing rate of about 20 kg / hr, and the melt was charged into a 50 stainless steel container (canister). This operation 1
The process was performed for about 6 hours a day for 10 days, and when the processing amount reached 1300 kg, the output change of the high frequency power supply device occurred, so the melting process was terminated. At this time, when the high-frequency induction heating furnace was opened and the melting container was observed, a part of the inner wall of the melting container was slightly consumed, and a trace of the exudation of the melt was observed. Therefore, in the melting container of the present invention, the effective processing time was about 60 hours under the above processing conditions.

Comparative Example When a molten container consisting of graphite having the same shape as that of Example was used and treated under the same conditions as in Example, the treatment amount was 120 k.
It was found that when it reached g, the melting vessel became unusable due to damage, and the graphite melting vessel could only be used for about 6 hours.

[Effects of the Invention] As described above, according to the present invention, the following effects are achieved.

By forming a melting vessel by uniformly or non-uniformly impregnating silicon carbide or silicon carbide and graphite with metallic silicon,
The thermal shock resistance is as good as that of graphite, and the oxidation resistance is remarkably improved.

By changing the inside or the outer wall surface of the melting vessel from graphite to silicon carbide impregnated with metallic silicon or silicon carbide and graphite, the life of the melting vessel is extended and the replacement frequency is reduced. As a result, the work time in the controlled area for maintenance is shortened, and when treating radioactive waste, exposure can be reduced.

By using silicon carbide or silicon carbide impregnated with silicon carbide as the material of the stopper, slag resistance and oxidation resistance are improved and the number of maintenances is reduced.

By reducing the frequency of replacement of hot parts,
The number of times equipment is used for replacement is reduced and the life of the equipment is extended.

The time during which continuous operation is possible becomes longer, and the time required for temperature rise and temperature decrease becomes shorter, enabling efficient processing.

[Brief description of drawings]

FIG. 1 is a side sectional view of a melting container according to the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a view for explaining a modification of the melting container of the present invention, and FIG. 4 is a melting treatment method of the present invention. It is a figure explaining. 1 ... Melting container, 2 ... Reservoir, 3 ... Extraction hole, 4 ... Stopper, 5 ... Miscellaneous waste, 6 ... Hopper, 7 ... Supply pipe, 8 ... High frequency induction heating coil, 9 ...... Stopper elevator, 10 ...... Melted and solidified product, 11 ...... Canister.

Claims (3)

[Claims] 1. In order to melt and process miscellaneous waste by using a high-frequency induction heating coil, a reservoir portion into which miscellaneous waste is charged and an extraction hole for taking out the melted miscellaneous waste are provided at the bottom or bottom. A hollow melting vessel, which is formed by uniformly or non-uniformly impregnating silicon carbide or silicon carbide and graphite with 10 to 20 wt.% Of metallic silicon with respect to the total amount. 2. In order to melt and process miscellaneous waste by using a high-frequency induction heating coil, a reservoir into which miscellaneous waste is charged and an extraction hole for taking out the melted miscellaneous waste are provided at the bottom or bottom. In a melting treatment method for miscellaneous waste, which melts miscellaneous waste in a hollow melting container, closes the extraction hole by using a stopper that fits in the extraction hole, opens the melt to continuously process A melting process of miscellaneous waste, wherein the melting vessel is formed by uniformly or non-uniformly impregnating silicon carbide or silicon carbide and graphite with 10 to 20 wt.% Of metallic silicon based on the total amount. Method. 3. The method according to claim 2, wherein the stopper is composed of silicon carbide, metal silicon-impregnated silicon carbide or metal silicon-impregnated graphite.