Rare Earth Metal Recovery Using Ionic Liquid Solvents
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Solution Overview
Problem
The recovery of rare earth metals from rare earth-containing materials is energy-intensive and contaminates the recovered metals due to high temperatures and the use of toxic reducing agents, and existing methods like electrowinning produce hazardous byproducts.
Innovation Solution
A method involving a reaction solution with a rare earth-containing material, a reducing agent, and an ionic liquid, where the rare earth metal is reduced and the reducing agent's cations are transferred to an electrochemical cell for regeneration, allowing for the recovery of elemental rare earth metals at lower temperatures and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional metallothermic reduction or thermal reduction methods are used to recover rare earth metals, then rare earth metals can be recovered from stable compounds, but the process requires high temperatures (greater than 1,000°C) and energy-intensive conditions
Solution Approach 1:
The patent changes the chemical parameters of the reduction process by using organometallic reducing agents with controlled reactivity and coordinating solvents that stabilize intermediates, enabling rare earth metal recovery at temperatures below 1,000°C while maintaining effective reduction of stable compounds
Solution Approach 2:
The patent employs composite reaction systems combining organometallic reducing agents (such as lithium trialkylborohydrides) with coordinating solvents (such as HMPT or THF), creating a synergistic system that lowers the activation energy required for reduction and enables lower temperature processing
2Reliability
If high temperatures and strong reducing agents are used to recover rare earth metals from stable compounds, then reduction can occur, but the reducing agent contaminates the recovered rare earth metal
Solution Approach 1:
The patent uses coordinating solvents that selectively bind to the reducing agent's byproducts (such as boron-containing species) while leaving the recovered rare earth metal unaffected, creating a localized purification effect that separates the reduction function from contamination
Solution Approach 2:
The patent introduces coordinating solvents as intermediary substances that mediate between the reducing agent and the rare earth metal, forming soluble complexes with the reducing agent's oxidation products and preventing them from contaminating the recovered metal
3Object-generated harmful factors
If conventional electrowinning methods are used, then rare earth metals can be recovered, but toxic hydrofluoric acid gas and rare earth fluoride salts are produced as hazardous byproducts
Solution Approach 1:
The patent changes the chemical parameters by using non-aqueous coordinating solvents and organometallic reducing agents instead of aqueous electrolyte systems, fundamentally altering the reaction pathway to eliminate fluorine-containing byproducts while maintaining effective rare earth metal recovery
Solution Approach 2:
The patent converts the potentially harmful reaction between reducing agents and moisture into a beneficial process by using coordinating solvents that control the reaction pathway, transforming what would be hazardous byproduct formation into a controlled reduction process with benign byproducts
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 reduces energy consumption, minimizes pollution, and recycles the reducing agent, achieving efficient rare earth metal recovery with lower temperatures and fewer hazardous byproducts compared to conventional methods.
Implementation Method 1
reducing the rare earth metal with the reducing agent to form a metallic rare earth metal and cations of the reducing agent
Implementation Method 2
transferring the cations of the reducing agent from the reaction solution to an electrochemical cell through an ion exchange membrane
Implementation Method 3
reducing the cations of the reducing agent in the electrochemical cell
Data Source
AI summary
A method of recovering an elemental rare earth metal comprises placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprising an ionic liquid or a eutectic mixture, reducing the rare earth metal with the reducing agent to form a metallic rare earth metal and cations of the reducing agent, transferring the cations of the reducing agent from the reaction solution to an electrochemical cell through an ion exchange membrane, and reducing the cations of the reducing agent in the electrochemical cell. Related methods of forming an elemental rare earth metal, and related systems are disclosed.