Uranium Chloride Production via Molten Alloy Halogenation
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Solution Overview
Problem
Current methods for producing uranium chloride are inefficient, generate hazardous waste, and require high temperatures, while also resulting in contamination and corrosion issues due to the use of chlorine compounds and higher melting metals like cadmium, which complicates the production of large quantities and leads to unwanted by-products.
Innovation Solution
A two-step method involving the halogenation of a metal in a low melting alloy with a halogen gas, followed by direct chlorination of a binary eutectic mixture, allowing for the production of uranium chloride at lower temperatures and minimizing waste generation by sequestering impurities and eliminating the need for chlorine-carrying metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing reaction pathways utilizing chlorine compounds are used, then uranium chloride can be produced, but residual lower or higher valent uranium chlorides remain and contaminate the salt
Solution Approach 1:
The patent applies preliminary action by pre-forming a eutectic mixture of NaCl-KCl-CsCl-MgCl2-CaCl2 before introducing uranium metal. This predetermined composition ensures the system is at the eutectic point, allowing direct formation of pure UCl3 without generating residual lower or higher valent uranium chlorides that would contaminate the salt.
2Ease of manufacture
If higher melting metals such as cadmium are used as chlorine carriers, then chlorine transport to metal is achieved, but additional process steps and disposal issues are created
Solution Approach 1:
The patent extracts and eliminates the chlorine carrier metal (such as cadmium) from the process entirely. Instead of using a higher melting metal to transport chlorine, the method introduces chlorine gas directly into the eutectic mixture containing uranium metal, simplifying the process by removing the intermediate carrier step and its associated disposal issues.
Solution Approach 2:
The eutectic mixture itself acts as an intermediary medium that facilitates the reaction between chlorine gas and uranium metal. The low melting point eutectic composition allows the system to maintain a liquid state at lower temperatures, enabling efficient mass transfer and reaction without requiring high-melting-point carrier metals.
3Productivity
If HCl or Cl2 is used as chlorinating agent, then uranium chloride production is achieved, but extensive corrosion occurs in ferrous metal containers
Solution Approach 1:
The patent changes the temperature parameter by utilizing the eutectic mixture, which maintains a liquid state at lower temperatures (around 400-500°C) compared to traditional high-temperature processes. This temperature reduction significantly decreases the corrosion rate of ferrous metal containers while maintaining high productivity through efficient mass transfer in the liquid phase.
Solution Approach 2:
The patent uses a composite eutectic mixture of multiple salts (NaCl-KCl-CsCl-MgCl2-CaCl2) rather than a single salt system. This composite material provides both the low melting point necessary for reduced temperature operation and chemical stability to minimize corrosion, while still enabling efficient uranium chloride production.
4Ease of manufacture
If organic chlorides such as CCl4 or CH2Cl2 are used, then chlorination reaction occurs, but phosgene gas is generated requiring waste treatment
Solution Approach 1:
The patent converts the potential harm of using chlorine gas (which can be corrosive and reactive) into a benefit by utilizing it in a controlled low-temperature eutectic system. The high reactivity of Cl2 that would normally cause corrosion and safety issues is harnessed efficiently at lower temperatures where the reaction proceeds completely to form only UCl3, eliminating the need for organic chlorides and their hazardous phosgene byproducts.
5Reliability
If NaCl is used alone, then good nuclear and chemical properties are achieved, but high melting point requires blending with other salts
Solution Approach 1:
The patent creates a composite eutectic mixture of five different salts (NaCl, KCl, CsCl, MgCl2, and CaCl2) in specific proportions. This composite material maintains the excellent nuclear and chemical stability of NaCl while achieving a dramatically reduced melting point through eutectic composition, allowing the system to operate at lower temperatures without sacrificing reliability.
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 enables the efficient production of high-purity uranium chloride with minimal waste, scalability, and reduced corrosion, suitable for industrial applications and integration with existing processes like electrorefining, while maintaining the uranium in a molten phase and controlling the valence state of the halide product.
Implementation Method 1
contacting the alloy with a halogen gas in a first reaction to halogenate the metal
Implementation Method 2
contacting the halogenated uranium with the salt bath in a second reaction to form a eutectic mixture comprising the mixed valent uranium salts
Implementation Method 3
A eutectic mixture is preferred over the binary chlorides within this process because it leads to a lower liquid temperature for the fluid, thus mitigating corrosion reactions
Data Source
AI summary
A method of producing uranium halides is disclosed in which chlorine gas is introduced into a liquid uranium-nickel alloy. NaCl salt is surrounding the crucible containing the liquid uranium-nickel alloy, producing a eutectic mixture of NaCl—UCl3. Upon chlorination, the metal halide dissolves in the matrix salt forming a solution. Adding the reactant metal, uranium to the nickel, the alloy is able to remain molten throughout processing. The liquid metal alloy may be removed from the salt bath, while the halogen gas continues to enter the system through the sparge until the desired composition of NaCl—UCl3—UCl4 is achieved. The method and system can be used to produce other metal halide salts such as actinide, lanthanide or transition metal halides contained in a matrix salt consisting of alkali and/or alkaline earth halides.