Highlights
- Recent advancements in rare earth separation technologies focus on improving efficiency, sustainability, and reducing environmental impact.
- Key developments include improved solvent extraction, membrane-based separation, electrochemical methods, and biotechnological approaches.
- These innovations aim to secure critical materials for high-tech and clean energy applications while reducing reliance on China.
Recent advancements in rare earth element (REE) separation technologies have been driven by the global need to secure critical materials for high-tech and clean energy applications while reducing reliance on China in the West. Key developments focus on improving efficiency, sustainability, and economic viability. Rare Earth Exchanges probes some of the advancements.
First comes solvent extraction improvements, remaining the most widely used method for separating rare earth elements, especially for high-purity production. Recent innovations focus on enhancing the efficiency and reducing the environmental impact of this process.
Within this category are included new organic solvents. Researchers are developing more selective organic solvents that target specific rare earth elements, reducing the number of extraction stages required.
An example would be green chemistry approaches. Innovations using bio-based solvents and less hazardous chemicals are being explored to make the process more environmentally friendly, minimizing toxic waste and energy consumption.
Another approach involves what’s known as membrane-based separation. Membrane technologies have emerged as a potential alternative or complement to traditional solvent extraction. Membranes with high selectivity for specific rare earth ions are being developed, offering a more energy-efficient and environmentally friendly method of separation.
Nano-filtration and ion exchange membranes are specialized membranes now under investigation for their ability to selectively separate rare earth elements, improving recovery rates while reducing chemical usage.
Polymer membranes represent another approach. Advances in polymer science are leading to the development of membranes that can target specific REE ions with high precision, offering potential for both primary extraction and recycling processes.
|
Technique |
Chemical |
Physical/ Thermal |
Electrical |
Biological |
|
Extraction/Pr-concentration |
|
|
|
|
|
Purification |
|
|
|
|
|
Separation |
|
|
|
|
|
Refining |
|
Vacuum reduction distillation Silocotheric/ Metallothermic reduction
|
Electrorefining Electrowinning Solid-state electron transport |
|
Electrochemical methods are gaining attention as a greener alternative to traditional solvent-based techniques.
Electrodeposition involves a method using electricity to selectively reduce and deposit specific rare earth elements from a mixed solution. By tuning the electrical potential, researchers are working to make this process more efficient for separating elements like neodymium, dysprosium, and terbium.
Yet another evolving approach: electrochemical ion exchange: the combining of electrochemical techniques with ion exchange resins is showing promise in improving selectivity and reducing energy consumption.
The use of ionic liquids (ILs) could be promising. ILs are a class of environmentally friendly solvents that have gained attention for their potential in rare earth separation. These non-volatile liquids can be designed to target specific rare earth elements, making the separation process more efficient and less polluting.
Recent research has focused on tailoring task-specific ionic liquids to selectively extract and separate different rare earths with fewer environmental impacts than traditional solvent extraction.
What about rare earth recycling and urban mining?
Rare Earth Exchanges has tracked some recent trends in this category. Recycling technologies for rare earth elements fromelectronic waste, magnets, and other products are advancing, focusing onboth extraction efficiency and sustainability.
For example, the use of hydrometallurgical processes involves researchers refining hydrometallurgical methods to recover rare earths from discarded electronics, using less aggressive chemicals and improved filtering techniques.
Another approach in this category involves the direct recycling of permanent magnets. As new processes allow the recovery of rare earth elements directly from permanent magnets in electronic devices, such as electric vehicle motors, without extensive chemical treatment.
Molecular recognition technology uses highly selective ligands that bind to specific rare earth ions. This method is based on a lock-and-key principle, allowing for highly efficient separation of individual rare earth elements from complex mixtures.
Companies like Ucore Rare Metals (opens in a new tab) have been working on MRT, which has shown potential for separating high-purity rare earths with minimal environmental impact compared to conventional methods.
A whole new class of separation approach is coming up in the laboratory environment involving novel biotechnological approaches. Biotechnologies are emerging as a novel approach to rare earth separation, using bacteria or bioengineered molecules to selectively bind to and concentrate rare earth elements. See a 2022 article from Lawrence Liver Laboratory (opens in a new tab) in Northern California.
Bioleaching means the dissolving of and concentrating rare earth elements from ores or recycled products, is advancing. This could provide a lower-cost, more environmentally friendly alternative to traditional mining and processing. Bioleaching, also known as biomining, is a process that uses microorganisms to extract metals from ores. It’s a natural process that involves interactions between microbes and minerals.
Meanwhile when it comes to genetically engineered peptides, scientists are working on peptides that can selectively bind to rare earth elements, providing a method for biotechnological separation that could be used in both mining and recycling contexts.
Just in May Nature covered the topics (opens in a new tab) of “Biosorption mediated by peptides or proteins” as a promising approach for selective REE recovery. To date, multiple peptides and proteins with high REE-binding affinity and selectivity have been discovered, and various strategies are being exploited to engineer robust and reusable biosorptive materials for selective REE recovery.
The authors are affiliated with University of Illinois, Urbana-Champaign.
Some startups involve themselves with artificial intelligence and machine learning, seeking to optimize separation processes by predicting the most efficient solvents, chemicals, or membrane structures for specific rare earth separations;
These models can simulate complex interactions between rare earth elements and solvents or membranes, enabling the design of more selective and efficient separation processes without extensive trial and error.
Other approaches could potentially be sustainable and “low-energy extraction techniques (supercritical C02 extraction or plasma separation for example).
Given the states in the West to wrestle supply chain dominance from China researchers in academia for example collaborate with partners including the competitive process to secure government contracts.
The U.S. Department of Energy (opens in a new tab) (DOE) has been actively funding projects aimed at improving rare earth extraction and separation, focusing on technologies that reduce environmental impact and enhance domestic supply.
Some key points about recent separation breakthroughs are included below.
- Protein-based separation:
Researchers have discovered proteins that can selectively bind to specific rare earth elements, offering a potentially cleaner and more efficient method compared to traditional chemical processes.
- RapidSX solvent extraction:
Ucore Rare Metals has developed a column-based solvent extraction system called RapidSX (opens in a new tab) that significantly speeds up the separation process by enhancing the mixing of aqueous and organic phases, leading to faster chemical reactions and lower operational costs.
- Ligand-assisted chromatography:
This technique, developed at Purdue University (opens in a new tab), allows for precise separation of rare earth elements using specialized ligands that selectively bind to different rare earth ions.
- Circular mineral harvesting:
Aclara Resources (opens in a new tab) is pioneering a method to extract heavy rare earths from ionic clays with high water recirculation and minimal waste generation, aiming to achieve a more sustainable process.
Potential impacts of these advancements:
- Reduced environmental impact:
By minimizing the use of toxic chemicals and waste generation, these new technologies could significantly lessen the environmental footprint of rare earth extraction.
- Improved access to rare earths:
By enabling more efficient separation and purification, these breakthroughs could help alleviate the current reliance on China for rare earth production.
- Enhanced recycling capabilities:
New technologies could facilitate the recycling of rare earth elements from old electronic devices and other products, contributing to a more circular economy.
Summary
The latest advancements in rare earth separation technologies are focusing on improving efficiency, sustainability, and reducing environmental impacts. From solvent extraction to innovative approaches like electrochemical and membrane-based separations, the goal is to secure rare earth supplies for critical industries while minimizing reliance on traditional, often polluting methods. Additionally, recycling technologies and biotechnological approaches are gaining traction, as countries and companies work to ensure a more sustainable and secure rare earth supply chain.
Daniel
You Might Also Like…