RU2353011C1 - Method of radioactive ion-exchanging resins preparation for immobilisation into bulk structures - Google Patents

Abstract

FIELD: nuclear power production industry.

SUBSTANCE: radioactive ion-exchanging resins preparation for immobilisation into bulk structures. Radioactive ion-exchanging resin is mixed with hard non-organic inert bulk material. After that, during mixing the above mixture is exposed to thermal treatment at the temperature no less than 250°C but not higher than 300°C.

EFFECT: reduction of power consumption, prevention of radioactive ion-exchanging resins products agglomeration after thermal treatment, prevention of radioactive ion-exchanging resins inflammation risk during thermal treatment, prevention of volatile resin and oil compositions formation, simplification of process, increased compatibility of radioactive ion-exchanging resins with cement-like materials after their thermal treatment.

Description

The inventive method of preparing radioactive ion exchange resins (RIOS) for immobilization in monolithic structures relates to the field of environmental protection, and more specifically to the field of processing liquid radioactive waste. The most effectively claimed method can be used to prepare RIOS for immobilization in cement matrix materials.

A known method of preparing RIOS for "... inclusion in binders operating at room temperature ..." (for example, cement-based binders) [A.S. Nikiforov, V.V. Kulichenko, M.I. Zhikharev, “Dehydration of liquid radioactive waste” , Moscow, Energoatomizdat, 1985, p.115], including preliminary mechanical dehydration of RIOS and removal of residual moisture from them by drying.

The disadvantages of this method are the increased duration of the process [A. S. Nikiforov, V. V. Kulichenko, M. I. Zhikharev, “Dehydration of liquid radioactive waste”, Moscow, Energoatomizdat, 1985, p. 115], as well as the fact that prepared thus, RIOS is poorly compatible with cement matrix materials, as RIOS has no changes in their ability to absorb water and swell.

A known method of preparing RIOS for immobilization in a cement-like matrix material (RU 2089950 C1, IPC ⁶ , G21F 9/30, op. 10.09.1997), including processing RIOS with sodium hydroxide. The mixture obtained as a result of RIOS preparation is mixed with water and crushed granulated blast furnace slag and maintained until a solid monolithic product is formed.

The disadvantage of this method is that the RIOS thus prepared are poorly compatible with cement-like matrix materials, because RIOS has no changes in their ability to absorb water and swell.

The closest in technical essence to the claimed is a method of preparing RIOS for immobilization in a cement matrix material described in the "Method for processing radioactive ion-exchange resins" (RU 2068208 C1, IPC ⁶ , G21P 9/32, op. 20.10.1996), including heat treatment of RIOS at 350-395 ° С until the ability to absorb water and swell is lost, cooling steam-gas heat treatment products to obtain oil-oil condensate and mixing oil-oil condensate with a solid residue obtained as a result of heat treatment of RIOS.

The disadvantages of this method are due to elevated temperatures of heat treatment:

- increased energy costs;

- the possibility of sintering heat treatment products RIOS;

- the risk of ignition of RIOS in the process of their heat treatment;

- the formation of volatile resin-oil compounds,

as well as:

- increased complexity of the process due to the presence of condensation of resin-oil compounds and mixing of condensate with solid RIOS heat treatment products;

- reduced compatibility of the mixture prepared with the above cement matrix, due to the presence in the mixture of a free organic resin-oil phase.

The technical result of the proposed method for preparing radioactive ion-exchange resins for immobilization in monolithic structures is the elimination of the disadvantages of the prototype, which consists in:

- reduction of energy costs;

- prevention of sintering of heat treatment products of RIOS;

- prevention of the risk of ignition of RIOS during their heat treatment;

- preventing the formation of volatile resin-oil compounds;

- simplification of the process;

- improving the compatibility of heat treatment products RIOS with cement materials.

The specified technical result is achieved due to the fact that RIOS is pre-mixed with solid inorganic inert bulk material, and the heat treatment of the resulting mixture is carried out with constant stirring at a temperature of not less than 250 ° C, but not more than 300 ° C.

Distinctive features of the proposed method are the following:

- the initial RIOS is pre-mixed with a solid inorganic inert bulk material;

- heat treatment of a mixture of RIOS with a solid inorganic inert bulk material is carried out with constant stirring at a temperature of not less than 250 ° C, but not more than 300 ° C.

In the process of heat treatment of a mixture of RIOS with solid inorganic inert bulk material, the RIOS is finally dehydrated, light fractions of the organic component of RIOS are decomposed, and hard-volatile compounds are coked, which leads to the melting of the surfaces of the RIOS granules (the formation of melted layers on the surfaces of the RIOS granules, screening their intrinsic zones of penetration moisture).

The presence of solid inorganic inert bulk material, which can be used as ordinary sand, quartz sand or ground blast furnace slag, in the environment of which RIOS heat treatment occurs with constant stirring, ensures uniform heat treatment of the surfaces of RIOS granules and prevents their sintering among themselves.

In addition, RIOS heat-treated in this way, due to their inability to absorb water and swell, have increased compatibility with cement matrix materials.

At temperatures lower than 250 ° C, the surface modification of RIOS granules is not ensured, and at temperatures above 300 ° C, energy consumption is not reduced, the sintering of the RIOS heat treatment products is prevented, the danger of ignition of the RIOS during the heat treatment is prevented, and the formation of volatile resin-oil compounds is ignored.

The method is implemented as follows.

RIOS is mixed with a solid inorganic inert bulk material, which is used as quartz sand with a volume ratio of RIOS / quartz sand = 4: 1, the resulting mixture in an amount of 7 liters is fed into a device equipped with a heat jacket, where it is heated to 275 ° C with constant stirring. after which the heat-treated mixture of RIOS and silica sand is thus discharged from the apparatus.

The unloaded products of heat treatment of a mixture of RIOS and quartz sand are bulk material with a volume of 4.7 l, and the process of heat treatment itself is not accompanied by ignition of RIOS and the formation of volatile resin-oil compounds.

When processing a mixture of RIOS with quartz sand in an amount greater than in the given example of a specific implementation of the ratio, the above technical result of the proposed method is also achieved.

Subsequently, the mixture obtained as a result of heat treatment can be divided into fractions of “heat-treated RIOS” and “inorganic inert bulk material”, which can be reused in the heat treatment process, and heat-treated RIOS can be immobilized in cement matrix materials.

Claims (1)

A method of preparing radioactive ion-exchange resins for immobilization in monolithic structures, including heat treatment of a radioactive ion-exchange resin, characterized in that the radioactive ion-exchange resin is mixed with solid inorganic inert bulk material before heat treatment, and heat treatment of the mixture of radioactive ion-exchange resins with solid inorganic inorganic material is carried out at a temperature of not less than 250 ° C, but not more than 300 ° C.