Composite Anode for Rare Earth Electrolysis
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Solution Overview
Problem
Existing electrochemical processes for producing rare earth metals and alloys face challenges in maintaining a balanced oxide concentration in molten fluoride electrolytes, leading to decomposition or sludge formation, necessitating an improved method for raw material supply and processing.
Innovation Solution
A method utilizing a composite anode made of rare-earth-oxide-carbon mixture, where the carbon reacts with oxygen from the oxide to release gas species and rare earth ions, which are then dissolved in a molten chloride electrolyte, allowing for controlled deposition of rare earth elements or alloys at the cathode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If raw material is continuously added at the top of the electrolyte, then oxide supply is maintained, but oxide concentration becomes unbalanced leading to decomposition or sludge formation
Solution Approach 1:
The rare earth oxide is pre-loaded into the porous anode structure during manufacturing, creating a reservoir that releases oxide gradually through diffusion and electrochemical reactions. This preliminary action eliminates the need for continuous addition and maintains balanced oxide concentration throughout the electrolysis process.
Solution Approach 2:
The porous anode acts as an intermediary between the external oxide supply system and the electrolyte. It controls the release of oxide through its porous structure and electrochemical reactions, preventing direct dumping of oxide into the electrolyte and thus avoiding concentration imbalances.
2Ease of operation
If oxide concentration is too low, then electrolysis continues smoothly, but fluoride electrolyte decomposes
Solution Approach 1:
The porous anode provides automatic feedback control of oxide concentration. As oxide is consumed in the electrolyte, the concentration gradient drives further diffusion and electrochemical release from the anode, maintaining oxide concentration within the optimal range and preventing electrolyte decomposition.
3Quantity of substance
If oxide concentration is too high, then raw material supply is sufficient, but oxides settle as sludge
Solution Approach 1:
Oxide is pre-distributed throughout the porous anode matrix before electrolysis begins. This preliminary distribution ensures gradual, controlled release into the electrolyte, preventing local oversaturation and subsequent sludge formation that would occur with batch addition.
4Ease of operation
If batch addition method is used, then operation is simple, but oxide concentration balance is poor
Solution Approach 1:
The porous anode is a self-regulating oxide supply system. It automatically adjusts oxide release rate based on consumption in the electrolyte through diffusion and electrochemical reactions, eliminating the need for complex control systems while maintaining precise oxide concentration balance.
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 approach mitigates the issues of low oxide solubility and sludge formation, enabling efficient production of rare earth elements or alloys with stable operation and even gas distribution, ensuring balanced electrochemical reactions and effective collection of products.
Implementation Method 1
the carbon reacts with oxygen from the oxide to release gas species and rare earth ions
Implementation Method 2
the rare earth element(s) in the anode is(are) electrochemically dissolved as rare earth metal ion(s) in the electrolyte
Implementation Method 3
cathode facilitating deposition of rare earth elements
Data Source
Figure 1
AI summary
The present invention disclose a method of producing rare earth elements or rare earth alloys in a molten salt electrochemical process, comprising steps of arranging an electrolysis cell with a solid composite anode comprising raw material and a cathode facilitating deposition of rare earth elements, wherein a molten salt electrolyte in the cell comprises chloride compounds.