Deep Eutectic Solvent Extraction of Rare Earth Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for extracting rare earth elements (REEs) from waste products like NdFeB magnets are not cost-effective and have negative environmental impacts, with traditional hydrometallurgical processes requiring toxic mineral acids and being inefficient, especially for end-of-life recycling.
Innovation Solution
A process using specific deep eutectic solvents (DESs) composed of hydrogen bond acceptor and donor compounds to extract REEs from metal or alloy form in NdFeB magnets without toxic acids, achieving high extraction rates and being economically advantageous.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional hydrometallurgical processes are used to extract REEs from NdFeB magnets, then extraction can be achieved, but toxic mineral acids are required and environmental impact increases
Solution Approach 1:
The patent changes the chemical parameters of the extraction system by replacing traditional mineral acids with deep eutectic solvents composed of choline chloride and carboxylic acids. This parameter change maintains extraction feasibility while eliminating toxic substances, directly resolving the contradiction between manufacturing ease and environmental harm.
Solution Approach 2:
The patent employs deep eutectic solvents that are inexpensive, biodegradable, and can be easily disposed of or regenerated compared to traditional ionic liquids or mineral acids. These solvents achieve effective extraction without the persistent environmental contamination associated with conventional methods.
2Ease of manufacture
If traditional hydrometallurgical processes are used to extract REEs from NdFeB magnets, then extraction can be achieved, but the process is inefficient and cost-effective
Solution Approach 1:
The patent optimizes extraction parameters by using deep eutectic solvents with specific molar ratios of choline chloride to carboxylic acid (1:2 to 1:5), operating at moderate temperatures (60-90°C), and controlling solid-to-liquid ratios (1:15 to 1:150). These parameter changes achieve over 50% extraction in less than 5 hours, significantly improving productivity while maintaining feasibility.
Solution Approach 2:
The patent employs periodic extraction cycles with multiple stages, where the deep eutectic solvent is applied in sequential batches or continuous flow cycles. This periodic action enhances overall extraction efficiency by allowing thorough contact between the solvent and magnet particles, achieving high recovery rates cost-effectively.
3Productivity
If deep eutectic solvents are used to extract REEs from NdFeB magnets, then extraction efficiency improves and environmental impact decreases, but solvent composition and preparation complexity increases
Solution Approach 1:
The patent segments the solvent system into two distinct components: choline chloride (hydrogen bond acceptor) and carboxylic acids (hydrogen bond donors). This segmentation allows each component to be independently sourced, characterized, and optimized, simplifying the overall preparation process despite the complexity of the eutectic mixture.
Solution Approach 2:
The deep eutectic solvents are prepared by simply mixing choline chloride and carboxylic acids in specific molar ratios, where the components self-organize into the eutectic structure through hydrogen bonding. This self-service approach eliminates the need for complex synthesis procedures, purification steps, or specialized equipment, reducing preparation complexity while maintaining high extraction efficiency.
4Productivity
If extraction time is reduced to less than 5 hours, then productivity increases, but extraction completeness may be compromised
Solution Approach 1:
The patent achieves rapid extraction (over 50% in less than 5 hours) by optimizing multiple parameters simultaneously: using deep eutectic solvents with specific molar ratios (1:2 to 1:5), operating at elevated temperatures (60-90°C), and maintaining optimal solid-to-liquid ratios (1:15 to 1:150). These parameter changes accelerate the extraction kinetics without compromising the ability to achieve high completeness through extended operation or multiple cycles.
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
The process effectively extracts high amounts of REEs like Nd, Dy, and Pr from NdFeB magnets with minimal environmental impact, suitable for industrial scale, and uses naturally occurring precursors to prepare cost-effective solvents, achieving over 50% extraction in less than 5 hours.
Implementation Method 1
A process using specific deep eutectic solvents (DESs) composed of hydrogen bond acceptor and donor compounds to extract REEs from metal or alloy form in NdFeB magnets without toxic acids
Implementation Method 2
Deep eutectic solvents based on choline chloride mixtures with hydrogen bond donors such as carboxylic acids, amines and alcohols have been studied for dissolving metal oxides
Data Source
AI summary
It relates to process for the extraction of rare earth elements from a starting product containing them in metal or alloy form which comprises: a) contacting the starting product containing rare earth elements in metal or alloy form with a deep eutectic solvent that consists of a mixture of a hydrogen bond acceptor (HBA) compound (A) selected from a salt of the formula Cat+X− (I), betaine or a salt thereof, and carnitine or a salt thereof; and a hydrogen bond donor (HBD) compound (B) in a molar ratio of (A) to (B) from 1:10 to 10:1, wherein the deep eutectic solvent is capable of extracting at least 50%w/w of one or more rare earth elements contained in the starting solid product in less than 5 hours, and b) separating the solvent containing the rare earth elements in dissolution from the undissolved solid.