JPS6126733A - Connected furnace for melting metal - Google Patents

Abstract

PURPOSE:To reduce the volume of radioactive metallic waste as well as to decontaminate the contaminated metal by melting the waste in molten slag, introducing only the molten metal into a clean solidifying furnace, and dropping it in clean molten slag. CONSTITUTION:A connected furnace for melting metal is composed essentially of a furnace 2 for melting radioactive metallic waste 1 and a solidifying furnace 10. The furnace 10 contains slag 15 which is cleaner than slag 3 in the furnace 2. Molten metal 4 in the furnace 2 is introduced into the furnace 10 and solidified, and a clean metallic ingot is taken out as a solidified ingot 14. When the molten metal 4 is solidified in the furnace 10, it is dropped in the clean slag 15, so the metallic ingot 14 coated with the clean slag 15 is taken out.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to decontamination and volume reduction treatment of radioactive metal contaminants, and is particularly suitable for the treatment of metal contaminants contaminated with transuranic elements. , relating to volume reduction processing.

[Background of the invention]

By dissolving metals contaminated with radioactive substances, especially metals contaminated with uranium, in molten slag material, uranium can be eluted into the slag material.

It has been reported by Copeland et al. as 0RNL/TM-6388.

However, the metal lump that has been solidified after melting is covered with slag material containing uranium. For this reason, the polished metal mass has slag material containing uranium attached to it, and the vitrified slag material has penetrated into the base metal, making it necessary to grind the surface. .

Furthermore, these methods have disadvantages in that uranium is re-deposited during grinding, and grinding debris needs to be remelted, making it impossible to remove uranium efficiently.

[Purpose of the invention]

An object of the present invention is to provide a method that enables decontamination and volume reduction of radioactive materials by dissolving metals contaminated with radioactive materials.

[Summary of the invention]

In the present invention, after metal contaminated with radioactive substances is melted in a molten slag material, only the molten metal is led to a clean furnace and solidified. That is, a melting furnace and a solidifying furnace are provided separately, and the furnaces are connected to guide the cleaned molten metal to the solidifying furnace. Furthermore, radioactive substances are eluted into the molten slag by dropping the molten slag material in the solidification furnace. This makes it possible to take out the metal lump covered with clean slag material.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

A contaminated metal lump 1 contaminated with radioactive substances is melted in a molten slag 3 in a melting furnace 2, and the molten metal accumulates as a molten metal 4 in the lower part of the melting furnace 2.

The metal lump 1 is held by a hanger 6 of a support column 5. The hanging tool 6 is driven up and down by an electric motor 7 provided at the lower part of the support column 5 via a reduction gear 8.

In the contaminated metal lump 1, Joule heat is generated in the molten slag 3 by applying a voltage between electrodes provided at the bottom of the melting furnace 2. The contaminated metal lump 1 is melted by this Joule heat, becomes droplets, and falls into the molten metal 4. During this time, contaminated metal lump 1
The radioactive substance adhering to the surface of is eluted into the molten slag 3. As a result, the molten metal 4 becomes a clean metal.

The molten metal 4 flows into the solidification furnace 10 from an opening provided at the bottom of the melting furnace 2 through a communication path 9 .

The molten metal entering the solidification furnace 10 from the communication path 9 falls in the molten slag 15 as droplets. During this time, uneluted radioactive substances in the melting furnace 2 are eluted into the molten slag 15, becoming even cleaner metal, which accumulates at the bottom and gradually solidifies.

The bottom member 11 of the solidification furnace 10 includes a support column 12. And it is held by a movable holder 13 attached to the support column 12 that can freely move up and down. The bottom member 11 is designed to prevent the communication path 9 from being blocked by the growth of the coagulum 14.

There is a molten slag 15 in the upper part of the solidification furnace 10, which moves downward as the solidified lump 14 grows.

It serves as a heating element to cool the molten metal at an appropriate rate. In this furnace, a stain electrode 17 is suspended from a holder 16 that is fixed to a support column 12 or is movable. A voltage is applied between the electrode 17 and the bottom member 11.

Similar to the melting furnace 2 described above, the module heat generated in the molten slag 15 prevents the molten metal from rapidly solidifying.

The solidification furnace 10 is cooled with a coolant such as water in order to prevent melting of the furnace walls and to cool and solidify the molten metal.

The holder 16 and the movable holder 13 are held at an appropriate height by an electric motor 18 and a speed reducer 19 provided at the lower part of the support column 12.

As described above, the molten metal 4 generated in the melting furnace 2 is turned into a solidified lump 14 in the solidification furnace 10 that holds clean slag material, so that the solidified lump 14 is covered with clean slag material. and can be taken out in a certain shape.

Therefore, compared to the original contaminated metal lump 1, the solidified lump 14U is at least equal to or smaller than that of the contaminated metal lump 1, and the volume can be reduced, and the storage space can be reduced compared to storing it in its original shape. for example,
The storage volume of 100A, 5chlos pipe material iom is 1.03 x 10@cm", and when it is melted, the volume becomes %1.05X10'crn3, about 1
The volume can be reduced to 1/0. In addition, because the shape is unified and streamlined, there is an effect of reducing wasted space during storage.

In this example, the contaminant metal was melted using a consumable electrode type electroslag remelting furnace; however, it is also possible to adopt a non-consumable electrode method, an induction furnace, a resistance furnace, etc. It doesn't matter. In addition, the furnace for producing the coagulated mass 14 is also the same, but compared to other furnaces, it is possible to deposit the coagulated mass 14 relatively continuously, and the shape of the solidification furnace 10 and the size of the solidified mass 14 are It has the advantage of being smaller than the . The communication path 9 is provided with a weir to prevent the molten slag 3 from flowing out when there is little molten metal 4 in the melting furnace 2. The height of the weir is such that due to the difference in specific gravity between the molten slag 3 and the molten metal 4, the weight of the molten slag 3 alone will not flow out.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the volume of metal contaminated with radioactive materials at the same time as decontamination, which makes it possible to reduce the amount of radioactive waste stored and the storage space required.・As the amount of radioactive waste is reduced, the number of facilities required for their safety management will be reduced.

In addition, since the obtained metal lump is covered with clean slag material, the slag material can be recovered and reused.
This has the advantage of eliminating the need for grinding to clean the surface and remelting of grinding debris.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a connected metal melting furnace according to the present invention. 1... Contaminated metal lump, 2... Melting furnace, 3... Molten slag. Bottom member, 12... Support column, 13... Moving holder, 1
4... Solidified lump 15... Molten slag 16... Holder.

Claims (1)

[Claims] 1. A furnace for melting radioactive metal waste, and introducing the molten metal into the furnace having a slag material that is cleaner than the slag material in the furnace, solidifying it, and taking out a clean metal lump. A connected metal melting furnace equipped with a melting furnace for producing solidified lumps, in which the molten metal to be solidified passes through clean slag material. 2. A connected metal melting furnace according to claim 1, characterized in that the liquid level of the clean molten metal is controlled to be lower than the molten metal inlet. 3. A connected metal melting furnace according to claim 1, characterized in that a weir is provided with a height determined by the difference in specific gravity between the molten metal and the slag material so that the slag material does not flow out at the outlet of the melting furnace. .