Guest post by Tyler Ozvat, 2019-2020 Sustainability Leadership Fellow and Ph.D. Student in the Department of Chemistry
A great variety of invaluable metals lie hidden and scattered underneath the Earth’s crust. We might think of precious metals like silver, gold, or platinum, however there is a series of less commonly known metals – the rare earth elements. Altogether, there are 17 different rare earth elements, each with tongue-twister names such as praseodymium, neodymium, gadolinium, dysprosium, and ytterbium. To be unfamiliar with these elements is to assume one has never held a smartphone! They are crucial for illuminating electronic displays, bringing sound to speakers, and other various inner workings of our smart devices. In fact, these prized metals are ubiquitous and enable many modern innovations including solar cells, wind turbines, light-emitting diodes, biomedical imaging agents, and a host of national defense technologies.
Our livelihoods are built upon the use of these technologies and we greatly depend on rare earth metals more than is commonly acknowledged. This lacking recognition results in significant wastage of unrecycled rare earth metals found in dated and obsolete electronic devices. Without recycling efforts for rare earth metals, electronic waste products that contain them are thrown away indiscriminately. Furthermore, the incessant production of next-year generation smartphones, laptops, and television screens increases the global demand for rare earth materials. For many big product-developing technology companies, such as Apple and Samsung, there is large dependence on the mining of rare earth metals. This dependence spurs depredation at large scale mining operations associated with outstanding environmental harm.
To say that rare earth mining operations have left an ecological footprint is a severe understatement. Seen in the picture above (left) is an open-cut, rare earth mine at Mountain Pass, California. This is an example of a dig site where massive excavation efforts are conducted to recover rare earth materials from the Earth’s crust. Mines like these are a result of the diffuse deposition of naturally occurring rare earth ore. Since they are found in low concentrations, greater areas of land must be unearthed. Once removed, rare earths ores require various extraction processes for refinement. This stage relies on the use of many potentially harmful chemicals, producing an additional range of environmental challenges.
The refining of rare earth ores depends on the industrial scale use of concentrated acids and solvents. In the picture above (right) is a satellite image of a lake outside of a rare earth refinery in Baotou, Inner Mongolia, China. This artificial lake bears the aftermath of several refinement and waste chemicals, including mixtures of unsuccessfully refined rare earths metals. Scenarios like these introduce harmful amounts of chemicals into the Earth’s crust and immediate landscapes. Inevitably, the production of rare earth metals for our technological use comes as the cost of environmental damage and chemical waste management discord.
What can be done to reduce the dependence on rare earth mining? The response is recycling. Ultimately, rare earth elements are in limited supply and very few alternatives would serve as substitutes for their technological capacities. Leading into the future, rare-earth-containing electronic waste will become essential resources for the recovery of these technology-critical metals. Unfortunately, current recycling methods are highly inefficient and can still produce large quantities of hazardous chemical waste similar to the refinement of rare earth ores.
So, mining and refining rare earth ore is harmful to the environment and recycling them is vastly inefficient – is there a solution?
In short, the answer could be magnetism! Understanding the role of magnetism in small molecules and atoms may be an answer to effectively separating and recycling rare earth metals from both ore and electronic waste. At Colorado State University, I am working in the Zadrozny group towards a fundamentally new design principle that could lead to a dissolution of obstacles surrounding the rare earth challenge. My research is performed in a chemistry lab and focuses on the reactivity of magnetic molecules containing rare earth metals. Through chemistry, I am excited to discover a reactive process that is magnetism-dependent and could provide liquids or solids enriched in one rare earth element from a mixture of others.
The challenge associated with the separation and recycling of rare earth materials is found in the nearly identical chemical properties of each element in the series. As a result of these similarities, the chemical methods that physically separate one rare earth metal from another is tricky. Recall that there are 17 different rare earth metals, and when there are mixtures of these metals together, they are exceedingly challenging to effectively isolate. In contrast to their chemically similarities, they have disparate and identifiable magnetic characteristics. It is the striking difference in the magnetism between rare earth elements that provides a reliable handle for designing an efficient chemical process for better separation. In this manner, the ability to control the reactivity between molecules through magnetism is potentially a powerful application that could be used for recycling rare earths metals.
Once a controllable method is resolved, these magnetism-based processes for rare earth elements will greatly help recycling efforts and reuse of these precious metals. In the meantime, I look forward to bringing awareness to the significance of rare earth elements and the current challenges associated with mining, refining, and recycling most importantly. Our rare-earth-containing technologies are essential to our wellbeing, but will only remain available to the extent of the chemical methods that can facilitate recycling.