JPS61250596A - Method of processing waste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for treating waste, and particularly to a method for treating waste containing hazardous substances.

[Conventional technology]

BACKGROUND ART Conventionally, various treatment methods such as cement solidification, asphalt assimilation, plastic solidification, and vitrification have been used to treat waste containing hazardous substances such as radioactive materials.

Cement solidification treatment methods may cause harmful substances to be leached depending on atmospheric conditions, and asphalt and plastic solidification treatment methods are chemically relatively stable but have drawbacks such as being sensitive to heat. .

Therefore, waste disposal methods by vitrification have become common.

This waste treatment method by vitrification involves adding an additive that causes vitrification to the waste, and vitrifying the additive and the waste together to prevent the waste from leaching out. This glass assimilation treatment method has the advantage of being more stable against heat, chemicals, etc. than other treatment methods such as cement solidification.

Although some waste materials, such as metals, do not undergo vitrification, these metals are encapsulated by the vitrified surrounding composition and are prevented from being released to the outside.

[Problem that the invention seeks to solve]

In the above-mentioned method for treating waste by vitrification, materials that are contained in waste and can become glass forming materials at relatively low temperatures (below 1300°C) are mixed with additives that cause vitrification and then heated and melted. Later cooling enabled processing based on vitrification. However, waste containing substances that cannot be used as glass-forming materials and relatively high temperatures (130
In the case of waste containing substances that cannot be vitrified unless heated to temperatures above 0°C, it is extremely difficult to solidify the waste by vitrification. This results in the release of radioactive substances that are harmful to the environment, and when vitrification is attempted at high temperatures, problems arise in terms of equipment durability and damage.

The present invention provides a waste that can efficiently and completely vitrify waste that contains substances that cannot be turned into glass-forming materials or that cannot be turned into glass-forming materials unless heated to a relatively high temperature. The objective is to provide a processing method for

[Means to solve the problem]

The inventors of the present invention have conducted various studies on waste treatment methods by vitrification treatment, and as a result have come to the following findings.

In other words, substances contained in waste that cannot be made into glass-forming materials as in the past, and substances that are also contained in waste and cannot be made into glass-forming materials unless heated to a relatively high temperature, are integrated with glass-forming materials. Rather than vitrification, these substances are wrapped in low-melting glass to prevent substances that cannot be used as glass-forming materials from leaching out, and substances that cannot be vitrified unless heated to high temperatures can also be wrapped in low-melting glass. I found out what I can do. That is, one aspect of the present invention is a method for treating waste and waste containing low melting point glass.

In the above structure of the present invention, silicon dioxide is the main component of the low-melting glass, and oxides made of alkali metals such as IJum and potassium oxide, and potassium oxide, etc.
There are some that contain um. In addition to this, there are also those that contain silicon dioxide as the main component and lead chloride and sodium oxide, and there are also those that contain boron oxide and lead oxide as their main components. In addition, it is also possible to melt and solidify these low melting point glass materials into a single powdered form and then melting them again, so these can also be used as low melting point glass materials.

These low melting point glasses should be heated at temperatures below 1000°C, preferably at 8°C.
It melts at about 00°C, and as a result of melting, bubbles are dispersed and bubbles are sufficiently broken.

When these low melting point glass materials are mixed with waste and heated and melted, each substance in the waste, especially harmful substances, becomes wrapped in low melting point glass, and the harmful substances are contained within the glass. therefore.

The release of hazardous substances from waste is prevented. These low melting point glasses melt at around 800 degrees Celsius.

It is possible to prevent wear and tear on the melting furnace that mixes and heats waste and glass-forming materials, and these operations can be performed quickly and easily.

〔Example〕

Next, one embodiment of the present invention will be described. This example uses calcium sulfate as the waste, which melts at 1500° C. and vitrifies the glass material.

Using a four-wave heating furnace, a commercially available low-melting glass material mainly composed of silicon dioxide and calcium sulfate, which has a relatively high melting temperature of 1500°C and causes vitrification at such a temperature, are mixed.
A metal crucible was used as the processing container.

It was observed that when these mixtures were heated to about 1000° C., calcium sulfate was wrapped in a low melting point glass forming material. In this state, calcium sulfate does not melt and is confined in the jL terraces. Of course, a small amount of calcium sulfate melts and becomes integrated with the low melting point glass forming material, causing vitrification.
You can get dust.

The mixing ratio of low melting point vitrification agent and calcium sulfate is
We changed the results as shown in the table and conducted a similar experiment. 1st
The table shows the solidification state depending on the mixing ratio.Table 1 As seen from Table 1, when the ratio (weight ratio) of low melting point glass material to calcium sulfate is 1:4 as in Experimental Example 1, waste The surface of the low-melting glass containing 20% was dense, but one surface had some unevenness.

In Experimental Example 2, the surface condition was similarly dense and there were no irregularities. In Experimental Example 3, one surface state was slightly porous. In Experimental Example 4, one surface state was porous.

Therefore, it is most preferable that the ratio of the glass material forming agent to calcium sulfate is 3. Therefore, when treating waste with a low melting point glass forming material, there is a most preferable mixing ratio.

These mixing ratios can be determined based on the amount and nature of the waste.

〔Effect of the invention〕

As explained above, according to the waste treatment method according to the present invention, the waste is included in a low melting point glass, and the glass surface is dense.

It is possible to prevent waste from being released into the environment.

Therefore, it is possible to prevent the release of harmful substances contained in the waste to the human body.

In addition, since low melting point glass is used to enclose waste, it prevents damage to the melting furnace and processing container due to heat.
Processing operations can be performed quickly and easily.

Claims (1)

[Claims] (1) A method for treating waste, which comprises mixing the waste and a low-melting point glass forming material and heating and melting the mixture to encapsulate the waste with low-melting glass.