Scientists at the Idaho National Laboratory (INL) have developed a low-cost, energy efficient process for recovering rare earth elements (REEs) and transition metals from waste magnets.
- The new process can be carried out under ambient temperatures and low-pressure conditions, reducing its costs and energy requirements, and does not rely on chemical reagents that would normally be wasted.
- REEs and transition metals will be crucial in achieving the 1.5°C target of the Paris Agreement, but supplies will have to be scaled dramatically in order to meet demand.
- As demand continues to rise, a range of technological innovations will be needed to ensure the reliability, affordability and sustainability of REE and transition metal supplies.
The researchers, who have published their work in a Nature Communications article, based their method on an existing water treatment technology that uses dimethyl ether – a gaseous compound known for its traditional use as a commercial refrigerant.
Dimethyl ether drives the process of fractional crystallisation, dividing chemical substances based on their solubility, allowing the scientists to recover REEs and transition metals from waste magnets.
As experimental lead Caleb Stetston explains, “This process begins with a magnet that’s no longer useful, which is cut and ground into shavings. The magnet shavings are then put into a solution with lixiviants, a liquid used to selectively extract metals from the material. Once the desired metals are leached from the material into the liquid, we can then apply a treatment process.”
Fractional crystallisation can be conducted under milder temperature and pressure conditions than conventional recovery methods, resulting in its lower costs.
Furthermore, it does not require any of the chemical reagents typically added, so avoids the environmental and financial consequences of their waste. Instead, the dimethyl ether solvent can be recovered and reused in future cycles.
Rising demand for REEs and transition metals as vital materials for decarbonisation
REEs, a collection of chemically similar metallic elements that tend to occur at low concentrations in nature and can be difficult to separate from one another, and transition metals – defined by their superior capacity as heat and electricity conductors – will play a crucial role in global decarbonisation efforts.
Several clean technologies rely on resources that fall within these categories. Lithium, nickel, cobalt, manganese and graphite, for example, are vital to the optimisation of battery performance, longevity and energy density. Copper and aluminium, meanwhile, are foundational to electricity networks and related technologies such as electric vehicles.
According to the International Energy Agency (IEA), a typical electric car is made using six times the mineral input of a conventional alternative, while onshore wind plants require nine times the volume of minerals needed for a gas-fired facility.
As the world transitions to a cleaner energy system, the demand for REEs and transition metals is set to explode. The IEA has said that concerted efforts to meet the 1.5°C target of the Paris Agreement would quadruple global mineral requirements by 2040, and that achieving net zero worldwide by 2050 would increase mineral demand to six times today’s levels within the same timeframe.
Research by McKinsey indicates that, to meet the rising demand for copper and nickel alone, between $250 billion and $350 billion of cumulative capital expenditure will be needed by 2030.
Challenges in REE and transition metal supplies
The IEA estimates that existing mines and projects under construction will only supply enough lithium and cobalt to meet 50% of projected demand by 2030, with copper only a little further ahead at 80%. As such, there is a dire need to scale the supply of these, and several other REEs and transition metals.
There are, however, significant environmental, social and economic concerns associated with conventional mineral supply chains.
Mining is extremely emissions intensive and involves the physical destruction of its surrounding environment. In addition to its physical impact on local ecosystems, mining operations cause chemical imbalances and toxic contamination that reduce biodiversity and cause health problems in nearby communities.
These consequences come with significant implications for environmental justice, with the majority of mining activities having been shifted to underserved countries in Africa and Asia.
As mining assets become increasingly exposed to climate risks such as water scarcity, extreme heat or flooding, operators within the sector face a contradiction between the pressure to become more sustainable and the need to scale their production.
Furthermore, the supply of REEs and transition metals is highly concentrated in a few select locations, leading to concerns around resource security. Global powers such as the EU, UK and US import the vast majority of their critical raw materials from countries such as China, resulting in geopolitical tensions that pose an additional challenge to mineral supplies.
Several solutions will be needed
The development of a reliable, sustainable and affordable minerals supply will not be straightforward, with McKinsey projecting a range of material shortages and corresponding price fluctuations. It observes that each individual commodity market will endure its own challenges, making it difficult to predict an exact trajectory.
There are, however, multiple avenues for technological innovation. Lack of affordable supplies will accelerate the development of alternative mineral recovery methods such as that developed by the INL researchers, as well as the exploration of different materials and recycling technologies.
This trend can already be seen in the development of chemical and bacterial solutions for recovering precious metals and minerals from electronic waste and in efforts to identify second-life opportunities for spent electric vehicle batteries.
Each of these solutions will contribute to the global transition. In all likelihood, it will take a range of innovative efforts coming together in unison, rather than the emergence of a singular strategy.
