JPS6022996B2 - Method for solidifying waste containing anion exchange resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for solidifying waste containing anionic resin or anionic resin with asphalt or plastic. The present invention relates to a method for preventing the generation of flammable gas during a kneading process and for increasing the ignition temperature of the solidified material itself.

Ion exchange resins are widely used for the treatment of industrial water and various types of wastewater, but these ion exchange resins eventually fail due to a decrease in ion exchange capacity and contamination with various pollutants. It is discharged as waste.

This waste is usually treated in some way from the standpoint of environmental protection; for example, ion exchange resin contaminated with radioactivity from nuclear power plants is currently solidified with cement. However, solidification with asphalt or plastic is increasingly being adopted, as it allows for a greater volume reduction than when solidifying with cement. Solidification with asphalt or plastic is generally done by kneading a mixture of waste and asphalt or plastic under heat using a hawker, etc.
This mixture is transferred to a drum or the like and then cooled to form a solidified substance.
If the waste contains anion-exchange resin or anion-exchange resin, heating at the temperatures normally used during kneading under this heating will decompose the anion-exchange resin and produce flammable gas. occurs, so this heating temperature must be lowered.

As a result, the efficiency of evaporating water decreases, so the waste must be sufficiently dried beforehand, and the solidified solidified waste and asphalt or plastic has a lower flash point than the solidified solidified asphalt or plastic alone. It has drawbacks such as: To explain this in detail below, the exchange groups of anion exchange resins include primary to
There are tertiary amines, quaternary ammonium, etc., but these exchange groups are unstable to heat, and base-based quaternary ammonium decomposes when the temperature exceeds 60°C. The primary to tertiary amines also decompose when the temperature becomes 100 qo or higher.

In particular, when the temperature is 120° C. or higher, the decomposition of these exchange groups becomes remarkable. When these exchange groups decompose, monomethylamine, dimethylamine, trimethylamine, etc. are produced, but since the boiling point of these amines is very low, at -7°C to 3°C, they immediately volatilize and become gases. Furthermore, these gases are flammable, so there is a risk of ignition if the concentration becomes high. Therefore, when anion exchange resin or waste containing anion exchange resin is mixed with asphalt or plastic, it is desirable that the heating temperature be 120° C. or lower. However, anion exchange resins or mixtures of anion exchange resins and intestinal ion exchange resins used for various types of water and wastewater treatment are usually discharged as a slurry with water or in a state containing a considerable amount of water. Therefore, when solidifying such waste as asphalt or plastic, the kneading temperature should be increased to 12
If the temperature is below 0°C, the efficiency of evaporating water during kneading will be very poor, and some water will remain in the solidified material. Remaining moisture in the solidified body is a problem because it reduces the strength of the solidified body. To avoid this, the waste must therefore be dried before kneading. Furthermore, if the waste is mixed at a temperature of 120°C or lower after drying in this way, the risk of ignition as mentioned above during mixing will be eliminated, and the moisture content of the solidified material will also be satisfactory. However, the flammability of the solidified material cannot be improved.

The flash point of the solidified material is approximately 180 qC, which is considerably lower than the flash points of asphalt alone and plastic alone, which are approximately 320 qC and approximately 380 qC, respectively, and is a problem in handling. The reason why the flash point of the solidified material is low is that the exchange groups of the anion exchange resin contained in the solidified material are decomposed by heat.
When solidifying waste containing anion exchange resin alone or anion exchange resin with asphalt or plastic, the present invention involves treating the waste with an aqueous solution of a phosphoric acid compound and solidifying it, or solidifying the waste with an aqueous solution of a phosphoric acid compound. The above-mentioned drawbacks are solved by solidifying the --shaped waste and the phosphoric acid compound together.

The present invention will be explained in detail below.

As mentioned above, the exchange group of an anion exchange resin is unstable to heat, especially when the exchange group is in the base form of quaternary ammonium. It has been found that flammable gases caused by trimethylamine, dimethylamine, monomethylamine, etc., as mentioned above, will not be generated even if heated within about 190 qo. We have discovered that it is possible to significantly raise the flash point of solidified plastic.

The method of converting the exchange group of the anion exchange resin in the waste into a phosphate form is to treat the waste with an aqueous solution of a phosphoric acid compound such as phosphoric acid, sodium phosphate, or potassium phosphate, or The phosphoric acid compound may be added directly to the waste slurry and mixed well. It goes without saying that the amount of phosphoric acid compound needs to be sufficient to convert the exchange groups of the anionic exchange resin in the waste into phosphoric acid form. According to the present invention, generation of flammable gas can be prevented even if the waste is heated to 19,000 ℃, so even if the waste is in a slurry state with water or contains a considerable amount of water, moisture may be present in the crosstalk. can be sufficiently evaporated.

Therefore, according to the present invention, it is not necessary to dry the waste beforehand as in the conventional method, and furthermore, the flash point temperature of the solidified material with asphalt or plastic formed according to the present invention can be increased to about 290°C. , about 180q, which is the flash point temperature of the conventional solidified material.
It has a great advantage in that the flammability of the solidified material can be significantly improved compared to . Note that the method of solidifying asphalt or plastic itself in the present invention may be any conventionally known method. Examples of the present invention will be described below.

Example In order to carry out the present invention, an ion exchange resin discharged when treating a condensate system of a boiling water nuclear power plant is assumed, and H-type and 0-type exchange groups remain. A mixed ion exchange resin was prepared by mixing a powdered strongly acidic cation exchange resin PCH (registered trademark, hereinafter referred to as the same product) PCH and a strongly basic anion exchange resin PADEX PAO at a ratio of 1:1.

The mixed resin was prepared in the form of a slurry with a water content of 80%, which is close to the water content that is normally discharged. In the method of the present invention, this mixed resin slurry is
Collect the female and add sodium phosphate (Na2HP04) to it.
To this, 5 pieces of asphalt were added and kneaded in a stainless steel container at a temperature of 180 qo using a Fumoto Azusa machine.

During this kneading, there was no particular amine odor, and no gas was observed to be generated from inside the kneaded product. After kneading for 1 hour, the falcon paste was left to cool and form a solidified product.

The flash point of this solidified material was measured according to the JIS K2274 test method and was found to be 290°C. Next, as a conventional method, the same mixed resin slurry used in the method of the present invention was used.
Using the same machine, 50 pieces of asphalt were prepared in terms of solids, and 5 pieces of asphalt were added thereto and kneaded at 180°C in a stainless steel container using a Sosshigaku machine. As a result, it was found that there was a strong amine odor when the wires were crossed, and that gas was generated from inside the kneaded product. After stirring the rice bran for 1 hour, the rice bran mixture was allowed to stand and cooled to form a solidified product.

The flash point of this solidified material was similarly measured according to the test method of JIS K2274 and was found to be 180. The above experimental results show that the present invention does not generate various flammable amine gases during kneading even when kneaded at 180°C, and the flash point of the solidified material formed by the present invention is significantly increased. It was confirmed that it did.

Claims (1)

[Claims] 1. When solidifying anion exchange resin waste or waste containing anion exchange resin with asphalt or plastic, the waste is treated with an aqueous solution of a phosphoric acid compound to solidify it, or the waste is in the form of a slurry. A method for solidifying waste containing anion exchange resin, which is characterized by solidifying waste by coexisting anion exchange resin with a phosphoric acid compound.