Bentonite Moisture Control via Fine Granular Ice Mixing
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Solution Overview
Problem
Existing methods for moisture content adjustment of bentonite used in geological disposals of radioactive wastes result in non-uniformity and require powerful mixers, leading to inefficiencies and poor performance as impermeable barriers due to granular lumps formation and significant shrinkage causing cracks.
Innovation Solution
A method involving the use of fine granular ice and low-temperature mixing environments to uniformly adjust the moisture content of bentonite, eliminating the need for powerful mixers and ensuring uniformity and impermeability through the use of a mixing tank or forcible feed pipe with low-temperature gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If water is added to pulverulent bentonite or water sprinkling is performed, then moisture content adjustment is achieved, but non-uniform moisture distribution and granular lump formation occur
Solution Approach 1:
The invention uses ice (solid phase) instead of liquid water to adjust moisture content. The ice particles are mixed with the pulverulent material in the frozen state, preventing premature water absorption and lump formation. The ice then melts uniformly throughout the mixture, achieving homogeneous moisture distribution without granular lump formation.
Solution Approach 2:
The invention introduces ice particles as an intermediary medium between the pulverulent material and liquid water. The ice acts as a controlled water delivery system, melting gradually to provide uniform moisture distribution rather than immediate water contact that causes lump formation.
2Productivity
If powerful mixers are used to stir and mix hydrous bentonite, then mixing is achieved, but device complexity and energy consumption increase
Solution Approach 1:
By utilizing the phase transition of ice to water, the invention eliminates the need for powerful mechanical mixers. The ice particles naturally distribute throughout the pulverulent material during gentle mixing, and their subsequent melting provides uniform moisture distribution without requiring high-power mixing equipment.
Solution Approach 2:
The invention replaces the mechanical mixing system with high-power mixers with a gentler mixing approach combined with ice particle distribution. The phase change of ice provides the mixing and distribution mechanism, reducing reliance on complex mechanical systems.
3Manufacturing precision
If conventional moisture content adjustment is performed, then moisture is added to bentonite, but significant shrinkage and crack formation occur during drying
Solution Approach 1:
The use of ice particles that melt uniformly throughout the pulverulent material ensures homogeneous moisture distribution. This uniform distribution prevents localized over-wetting and subsequent excessive shrinkage during drying, thereby minimizing crack formation.
Solution Approach 2:
The invention achieves homogeneous moisture distribution by mixing ice particles with the pulverulent material before melting. This homogeneity ensures uniform drying characteristics throughout the material, preventing differential shrinkage and crack formation.
4Quantity of substance
If water is added in advance of sufficient stirring and mixing, then moisture content is adjusted, but only bentonite in contact with water becomes granular lumps
Solution Approach 1:
By adding ice in the solid phase rather than liquid water, the invention prevents immediate water absorption by bentonite particles. The ice particles remain distinct and distributed throughout the mixture, melting gradually to provide uniform moisture distribution rather than creating localized granular lumps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves uniform moisture content distribution, reduces the need for powerful mixers, prevents granular lump formation, and enhances the impermeability and density of bentonite, ensuring effective cut-off performance and minimizing crack formation during drying.
Implementation Method 1
A method involving the use of fine granular ice and low-temperature mixing environments to uniformly adjust the moisture content of bentonite
Implementation Method 2
use of fine granular ice and low-temperature mixing environments
Data Source
Figure 1~2
Figure 3~4
AI summary
When making moisture content adjustment by adding liquid such as water to a raw material such as pulverulent material including bentonite, uniform mixing of the liquid such as water with the raw material is given with relatively simple facilities, moisture content adjustment of a large quantity of raw materials is attainable, and besides, a material having satisfactory performances such as impermeability is obtainable through uniform moisture content adjustment. Within a mixing tank (1) configured with a normal powder mixer kept at low temperatures, pulverulent bentonite (A) and fine granular ice (B) are stirred and mixed. Stirring and mixing of the fellow pulverulent materials are adapted to uniformly mix the pulverulent bentonite (A) and the fine granular ice (B), enabling uniformly moisture content-adjusted bentonite to be obtained. A liquid-nitrogen gas bomb (21), for instance, is connected to the mixing tank (1), causing the inside of the mixing tank to be kept at low temperatures with nitrogen gas supplied from the bomb, before putting the prepared fine granular ice (B) through an inlet port (20).