Technique for preparing dryness gel ball by using vacuum drying method

Abstract

This invention relates to a vacuum-drying method for preparing dry gel spheres. After aged and washed, the gel spheres are vacuum-dried. The prepared dry gel spheres have low breakage rate, high surface uniformity and ideal structure. When dried during motion, the gel spheres are uniformly heated and there is no adhesion among the gel spheres. The method adopts a vacuum rotary dryer to realize aging, washing and drying procedures, thus having such advantages as compact equipment, easy operation and high efficiency. Besides, the transfer amounts of radioactive materials are reduced, which is good for the environment.

Description

technical field [0001] The invention relates to a treatment method for gel balls prepared by a sol-gel method, in particular to the aging, washing and drying process of the gel balls when the sol-gel method is used to prepare spherical nuclear fuel particles. Background technique [0002] Spherical nuclear fuel particles are an important part of high-temperature gas-cooled reactor fuel elements, and the mainstream process currently used is the sol-gel method. Generally, it goes through the steps of sol preparation, gel forming into balls, aging, washing, drying, roasting, and reduction sintering. This process was developed in the 1960s. Its principle is to dissolve the powder raw materials and make a sol, then disperse the sol into balls and gel the sol under the action of a medium to become a gel ball, and then the gel ball passes through Washing, drying and dehydration, calcination decarburization, reduction deoxidation and sintering to obtain nuclear fuel particles with ...

AI Technical Summary

Problems solved by technology

This process can realize continuous operation, but the biggest problem is that the dried balls tend to be dry on the outside and wet on the inside, which will eventually lead to a shell structure, thereby reducing the yield, and the balls are prone to sticking between balls

[0005] The gel ball drying process disclosed in Chinese patent 90109445.5 uses an azeotropic still, a microwave oven and an oven. The disadvantages are that the process is long, the operation is complicated, and the process is difficult to control.

When the drying speed is too fast, the moisture and gas in the wet bulb will escape too quickly, which will easily lead to the cracking of the pellet; if the drying speed is slow, the wet bulb will shrink greatly during the drying process, and the surface of the particles will become compact, which is not conducive to the subsequent calcination carry out

Moreover, this process cannot meet the needs of large-scale production

[0006] The drying method of the gel ball also includes the method of airing in the air (atomic energy science and technology, 24 volumes, the 4th period, 10-15), which spreads the wet ball on a steel mesh or a nylon net for drying, and this method requires a certain humidity. , each batch of drying needs 12-18 hours, the production efficiency is very low, and the balls are also easy to stick to each other

[0007] The vacuum drying process is generally used for the drying of powdery, granular and fibrous materials and the concentration of liquid materials, but it has not been used in the gel ball drying process for preparing spherical nuclear fuel by the sol-gel method.

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