JPS6265730A - Tableting granulator - Google Patents

Abstract

PURPOSE:To prolong the useful hours of the titled tableting granulator and to reduce the generation of dust by forming a rod and a die part for granulating granular particles and burnt ashes with a ceramic having high wear resistance and compressive strength. CONSTITUTION:A ceramic part is provided on the tip end of a rod 10, fixed with a machine screw and made exchangeable. A ceramic part is shrinkage- fitted on the inside of a die 8 and likewise made exchangeable. As an alternative method, a ceramic 15 highly resistant to deformation is fitted on the part of the ceramic fitted on the rod 10 and the die 8 to be severely deformed and a ceramic 16 highly resistant to wear is fitted on the part to be severely worn. Deformation and wear are appropriately prevented in this way. Since the resistance to wear and deformation of the ceramic differs in dependence on its kind, an appropriate material can be selected in accordance with the service condition of the granulator.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for granulating powder and granules and incineration ash generated when radioactive waste generated from nuclear facilities is dried, incinerated, or incinerated. The present invention relates to a tablet-type granulator, and in particular to a molding rod and die.

[Background of the invention]

In recent years, there has been an increasing trend toward reducing the volume of radioactive waste generated from nuclear facilities, and responsiveness to trends in the final disposal of radioactive waste has become important. For this reason, at each nuclear facility, liquid radioactive waste and slurry radioactive waste are dried or incinerated into powder, combustible miscellaneous solid waste is incinerated into incineration ash, and furthermore, they are Alternatively, the technology of mixing and granulating is being put into practical use, and is already in operation in some cases.

Next, the granulation mechanism of the tableting type granulator will be explained. There are two types of tablet granulators, vertical and horizontal, depending on the direction of tablet compression.
The granulation principle is the same.

FIG. 1 is a diagram showing the granulation mechanism of a horizontal tablet-type granulator. The powder or incineration ash to be granulated.

From chute tube 2 attached above hopper 1 to hopper 1
be thrown inside. In the hopper 1, the powder or incinerated ash is cooled and cooled by stirring blades 4 rotated by an electric motor 3.
While being prevented from adhesion etc., it is supplied into the granulation section 6 by the supply blades 5 which are also rotated by the electric motor 3.

At the bottom of the granulation part 6, an entry die 7 is placed across the granulation part 6.
and exit side dice 8 are installed. Furthermore, the entrance die 7
An inlet rod 10 and an outlet rod 11 driven by a piston 9 are housed inside the outlet die 8 and can be moved freely in the horizontal direction by the driving piston 9.

The powder or incinerated ash is compressed and molded by the inlet rod 1o and the outlet rod 11 in the outlet die 8, and then transferred to the outside of the outlet die 8 through the pellet chute pipe 12 to other equipment. I will be sent.

FIG. 2 is an example showing details of the granulation operation. The powder or incinerated ash 13 initially filled to the bottom of the granulation section 6 is (
(2) The material is transferred into the exit die 8 by horizontal movement of the entry rod 10 and the exit rod 11. (■). The transferred granular material or incinerated ash 13 is compressed by an inlet rod 10 and an outlet rod 1 having a large compression force by a piston 9.
1, the pellets are compressed within the outlet rod 8 and become pellets 14.

(■). The shaped pellets 14 are transferred horizontally between the inlet rod 10 and the outlet rod 11, taken out from the outlet die 8, and sent to other equipment.

As can be seen from Figure 2 ■ and ■, the exit die 8 is used during granulation.
Compressive stress due to a large compressive force and frictional force due to the transfer of powder or ash 13 or pellets 14 are generated in the inlet rod 10 and the outlet rod 11. Therefore, in conventional general industry, alloy tool steels (SKS, SKD, etc.) with excellent wear resistance and deformation resistance have been used as materials for dies and rods.

However, when applying a tablet-type granulator to nuclear power, due to the unique conditions of nuclear power as shown below, it is necessary to use a material that has better wear resistance and deformation acid resistance compared to the conventionally used alloy tool steel. It turned out to be a big advantage.

(1) In nuclear power applications, the powder or ash to be granulated is radioactive waste, so strict control is required of its quality, especially its strength, in order to ensure final disposal. Therefore, high compressive force is required to increase the strength, resulting in high compressive stress in the rod and die.

(2) For nuclear power applications, one of the main components of the powder or incineration ash that is to be granulated is the dried powder of concentrated waste liquid. It contains hard materials such as generated crud or silica deposited on the floor, etc., and is more abrasive than powders that were conventionally used for granulation in general industries such as the pharmaceutical industry.

(3) In nuclear power applications, the powder and granules or incinerated ash contain radioactive materials, so their scattering is unacceptable. Therefore, from the viewpoint of preventing this, the clearance between the rod and the die must be strictly controlled, and the amount of wear and deformation must be kept lower than for general industrial use.

(4) For nuclear power equipment, the frequency of replacement must be minimized even if the parts are inexpensive, from the perspective of reducing radiation exposure for workers and reducing the number of companies producing radioactive waste.

FIG. 3 shows the dimensional changes of the rod and die confirmed by the present invention through tests. For dies, the part that compresses and molds the pellets has the largest deformation, and the area between the compression molding part and the pellet outlet also has a relatively large deformation.As for the rod, the tip that compression molds the pellets has the largest deformation; No residual deformation occurs in the area beyond the diameter of the pellet.

[Purpose of the invention]

An object of the present invention is to provide rods and dies for a tablet-type granulator that increase the service life of the tablet-type granulator and reduce the amount of dust generated by using ceramic rods and dies. It is in.

[Summary of the invention]

Generally, the amount of wear of a material is determined by the relationship between the hardness of the material and the hardness of the substance being handled, and the amount of deformation of the material is determined by the Young's modulus and compressive strength of the material.

First, regarding wear, even if the hardness of the material is greater than the hardness of the substance being handled, the effect of reducing the amount of wear is small, so the material must have at least twice the hardness of the substance being handled.

The deformation is determined by the amount of deformation when compressive stress is generated, that is, the Young's modulus, and the compressive strength, that is, the ratio of the stress that causes mold deformation to the stress that is generated. Therefore, the greater the Young's modulus and compressive strength of a material, the better the deformation resistance.Table 6 shows a comparison of various physical properties of conventional alloy tool steels and various ceramics.

As can be seen from the above, the use of ceramics has greatly improved various physical properties, especially in terms of wear resistance.
Whereas conventional special tool steels had only about half the hardness of V500), ceramics have more than twice the hardness, which is an advantage in terms of reducing wear. A significant effect was observed.

Ceramics also have larger values in terms of Young's modulus and compressive strength than conventional special tool steels, and are also effective in reducing deformation.

As shown in the table above, the wear resistance and deformation resistance of ceramics vary depending on the type, so the usage conditions of the granulator,
For example, an appropriate material can be selected depending on the amount of stress generated and the hardness of the material to be handled.

[Embodiments of the invention]

FIG. 4 shows one embodiment of the invention. In this embodiment, a ceramic part is provided at the tip of the rod 10 and fixed with screws so that it can be replaced. Also, a ceramic part is shrink-fitted inside the die 8 so that it can be replaced as well.

FIG. 5 shows one of the other embodiments of the present invention. In this embodiment, among the ceramics attached to the rod 10 and the die 8, ceramics 15 with high deformation acid resistance are attached to the parts where the deformation is large, and ceramics 16 with high wear resistance are attached to the parts where the wear is large, so that appropriate deformation can be achieved. , to prevent wear.

In the case of this embodiment, the ceramics are bonded together.

〔Effect of the invention〕

The present invention provides rods and dies that have excellent wear resistance and deformation acid resistance.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the granulation device. Figure 2 is a diagram of granulation operation. Third
The figure shows the dimensional changes of the rod and die. Fourth
FIG. 5 is a detailed explanatory diagram of the present invention. 7.8... Dice, 10.11... Rod, 13.
... Powder, 14... Pellet, 15.16... Ceraminx.

Claims (1)

[Scope of Claims] 1. A tablet-type granulator, characterized in that the rod and die parts for granulating powder and granules and incinerated ash are made of ceramics with high wear resistance and compressive strength. 2. A tablet-type granulator according to claim 1, characterized in that only a portion of the rod and die are made of ceramics. 3. A tablet-type granulator according to claim 2, characterized in that the ceramic parts of the rod and die are replaceable. 4. In claims 1 to 3, the ceramic is silicon nitride, silicon carbide, aluminum nitride, silica, alumina, zirconia, or two of these.
A tablet-type granulator characterized in that it is a mixture of three or more.