Spent Uranium Catalyst Volume Reduction via Alkali Dissolution
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Solution Overview
Problem
The disposal of spent uranium catalysts is challenging due to high volume and radioactivity, with existing methods being costly and inefficient, and failing to meet disposal criteria, particularly due to the difficulty in separating and processing uranium components effectively.
Innovation Solution
A treatment method involving selective dissolution of the silicon support component in an alkali solution, followed by solid-liquid separation, precipitation of silicon dioxide and uranium phosphate, and subsequent glassification to form a glass-ceramic composite medium, which reduces waste volume and improves leaching characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cementation for solidification is performed for direct treatment of powdered spent uranium catalyst, then the waste can be stabilized, but the volume of final wastes increases to 10,000 to 20,000 drums
Solution Approach 1:
The patent extracts and removes the silicon component from the spent uranium catalyst through selective dissolution in alkali solution. This separation isolates the radioactive uranium-containing residue from the bulk silicon support material, thereby reducing the volume requiring disposal while concentrating the radioactivity in a smaller, more manageable form.
Solution Approach 2:
The patent changes the chemical parameters of the waste treatment process by using selective dissolution in alkali solution rather than conventional cementation. This parameter change transforms the treatment approach from physical encapsulation to chemical separation, enabling volume reduction while maintaining stabilization through subsequent glass-ceramic formation.
2Quantity of substance
If uranium components are completely separated from spent uranium catalyst, then pure uranium can be recovered, but the separation process is extremely difficult and the separated uranium waste has higher radioactivity concentration exceeding disposal limits
Solution Approach 1:
Instead of attempting complete separation of uranium components, the patent selectively extracts only the silicon support material. This partial extraction approach simplifies the process significantly while achieving the primary goal of volume reduction. The uranium remains in a diluted state within the residue, automatically meeting disposal radioactivity limits without requiring complex further separation.
Solution Approach 2:
The patent converts the presence of uranium in the waste stream from a problem into a benefit. By not attempting complete removal, the uranium acts as a natural tracer and stabilizing agent in the final glass-ceramic product. The diluted uranium concentration automatically satisfies disposal criteria, turning what could be a contamination issue into a simplifying feature of the process.
3Volume of moving object
If silicon component is selectively dissolved and discharged to meet clearance criteria, then volume reduction is achieved, but the dissolution process requires careful control to ensure radioactivity limits are met
Solution Approach 1:
The patent uses glass-ceramic formation as an intermediary step between dissolution and final disposal. This intermediary process provides a controlled mechanism to achieve both volume reduction and radioactivity management. The glass-ceramic matrix allows precise control over the distribution and fixation of radioactive elements, ensuring disposal criteria are met while maximizing volume reduction.
Solution Approach 2:
The patent creates a composite glass-ceramic material that combines the dissolved silicon residue with uranium-containing phases. This composite structure provides inherent stability and control over radioactivity distribution. The composite nature allows the material to simultaneously achieve volume reduction, stabilization, and compliance with disposal criteria through its integrated structure.
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 significantly reduces the volume of spent uranium catalysts for disposal, stabilizes the waste, and meets the necessary radioactivity clearance criteria, enhancing the efficiency and cost-effectiveness of the disposal process.
Implementation Method 1
selective dissolution of the support component by immersing the spent uranium catalyst in an alkali solution
Implementation Method 2
selectively precipitating the silicon ions included in the dissolution solution as silicon dioxide
Implementation Method 3
precipitating uranium ions as uranium phosphate by adding phosphate to the residual solution separated in the step 4
Implementation Method 4
heat-treatment to fix the mixture in the form of a glass-ceramic composite medium
Implementation Method 5
heat-treatment to fix the mixture in the form of a glass-ceramic composite medium
Data Source
AI summary
A volume reduction treatment method able to reduce the volume of the final disposal waste of a spent uranium catalyst. As a result, the disposal cost of the spent uranium catalyst is able to be reduced and the utilization of waste repositories are able to be improved.