To most people outside of the fields of specialized engineering, or geology and chemistry, Rare Earth Elements (REE) were relatively unheard of until the late 20th century. However, with the advent of modern technology and the demand thereof, these minerals have garnered considerable visibility worldwide. This demand is primarily due to their specialized properties and important daily uses.
But even if by name, REEs are foreign to the majority of people, most of us have, at some point or another, witnessed these vital elements hard at work in our everyday lives without us even realizing it.
That's because Rare Earth Elements can be used in high-technology devices such as flat-screen TVs, digital cameras, smartphones, LED lights, computer hard disks and monitors, and electronic displays.
But what exactly are rare earth metals, are they really rare, and how are they changing engineering and our daily lives? Read on for answers to these questions and more:
What Are Rare Earth Metals
As mentioned above, these vital metals rarely receive the attention and respect they deserve outside scientific and engineering communities. Then again, with hard-to-pronounce names like neodymium, ytterbium, and praseodymium, it’s little surprise they are hidden at the very bottom of the periodic table.
But don’t be fooled by their table ranking. These tongue-twisting metals are so important in everyday use that we can barely get through a productive day without them. That’s unless you’ve gone off-grid and have no service for modern gadgets.
So, what exactly are REEs? The widely accepted definition is that they are a group of 17 rare earth elements in the lanthanide series that all exhibit similar chemical properties. Classified as ‘transition metals’, they are listed as follows: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, plus yttrium and scandium.
Some scientists, however, may exclude scandium or yttrium and scandium from the rare earth grouping. This usually depends on how similar these are to scandium or yttrium. Also known as rare earth metals; REEs were discovered in 1787 by chemist Lieutenant Carl Axel Arrhenius after he found a strangely heavy, black rock in a quarry in Ytterby, Sweden, which he named ytterbite.
Although scientists had initially, for some decades, pondered these elements with no meaningful results, they eventually realized their great potential, such as their incredible magnetic and conductive properties, allowing us to shrink our techie devices. Our older readers will recall the 1970s-era Sony Walkman, the first portable music device. The compact player was made possible partly because it contained a small, strong magnet from samarium.
And this paved the way for even smaller high-tech devices in that arena, such as the Walkman's diminutive descendant, the iPod. These days, samarium-based magnets have been replaced by even smaller, stronger neodymium ones. REEs also shine in the defense arena, where they're used to create everything from precision-guided weapons to those ultra-cool night-vision goggles and more.
So, How Rare Are They?
Their name may suggest otherwise, but the fact is that Rare Earth Elements can be found in relative abundance around the world. What makes them rare at present is that it is rare to find a commercially viable deposit.
China has long cornered the REE global market and is still leading, with global mine production reaching 140,000 metric tons of Rare Earth Oxides (ROE) in 2020, accounting for almost 60 percent of the worldwide output. However, China has some competition, with the USA trailing behind with a 16 percent share of global rare earth production as of 2020 or 38,000 metric tons ROE.
And other countries have also joined the race, such as Myanmar, closely following America by increasing its mine production in recent years. Myanmar’s efforts have given it a 12 percent share of the global output, amounting to 30,000 metric tons ROE. Other countries are Australia, Madagascar, India, and Russia.
For instance, in an interview with Mining Technology, Australian miner Arafura Resources noted that global consumption of rare earth oxides reached around 167,000 tonnes in 2020. The mining firm expects this figure to balloon to approximately 280,000 tonnes over the next ten years.
The good news for Australia is that it could be one of the primary beneficiaries of this dramatic increase in demand, where private companies and local governments alike are eager to expand the country’s nascent rare earth production.
In 2021, Australia produced the fourth-most rare earth in the world. Its total annual production of 19,958 tonnes remains significantly less than the mammoth 152,407 tonnes produced by China but is still a dramatic improvement over the 1,995 tonnes produced domestically in 2011.
Positive Impact On Daily Life
When it comes to their impact on engineering, the experts in this field believe Rare Earth Elements have the potential to transform technology in previously unprecedented ways. The magnetic, luminescent, and electromechanical capabilities of REEs allow electronic devices to become more compact, reduce emissions, operate more efficiently, and cost less to produce and purchase.
These developments benefit global economies because of their use in popular everyday consumer technologies and industries such as energy. However, with this positive impact comes a political overlay that threatens the longevity of REE use.
At the moment, the elements are incredibly costly and dangerous to extract because separating rare earth from other materials involves processes with high levels of emissions that may be dangerous to human beings if overexposure occurs.
With global demand for vehicles, consumer electronics, energy-efficient lighting, and catalysts expected to rise rapidly over the next decade, the possibility of extracting rare earth through more efficient, safer processes is becoming a relevant research topic.
REEs In New Engineering Applications
Aside from the myriad ways that REEs are making the lives of the general population more convenient, they are demonstrating great potential to modify modern engineering in an extraordinary way.
In their case study, Monika Duchna from the Faculty of Materials Science and Engineering at Warsaw University of Technology, Poland, and Iwona Cieślik from Poland’s National Centre for Nuclear Research with advances in all fields of engineering, it is predictable that the rare earth elements will play a crucial role.
The development of wind energy will continue to drive demand for REE used in wind turbine generators while converting combustion engine cars to electric ones will also increase the need for magnets and rare earth batteries.
Of course, the search is ongoing and materials that could replace or reduce the amount of REE in individual applications are considered.
Questionable Extraction Methods
The growing demand for rare earth like dysprosium and neodymium is predicted to increase exponentially over the next 25 years as a result of electric vehicles and wind turbines. However, while acknowledging the green benefits of REEs, environmentalists are also concerned about the grim prospects of the minerals. Currently, the two primary ways with which companies extract REEs largely damage communities and contaminate surrounding areas.
According to an article titled Not So “Green” Technology: The Complicated Legacy of Rare Earth Mining, in the Harvard International Review, the first involves removing topsoil and creating a leaching pond where chemicals are added to the extracted earth to separate metals. This form of chemical erosion is common since the chemicals dissolve the rare earth, allowing it to be concentrated and then refined. However, leaching ponds, full of toxic chemicals, may leak into groundwater and can sometimes affect entire waterways.
In the second method, mining companies drill holes into the ground using PVC pipes and rubber hoses to pump chemicals into the earth. In addition to creating a leaching pond with similar problems to the first method, these pipes are sometimes left in areas that are never cleaned up.
The mining process for a ton of REE produces 13kg of dust, 9,600-12,000 cubic meters of waste gas, 75 cubic meters of wastewater, and one ton of radioactive residue. That’s because there are metals in rare earth element ores metals that, when mixed with leaching pond chemicals, actually contaminate soil, water, and air. As they are often laced with radioactive thorium and uranium, REE ores also pose detrimental health effects.
The Way Forward
As affected communities and businesses using the controversial current extraction methods scramble for safer alternatives to mining REEs, chemical engineers and researchers are stepping up to the plate.
At Havard, a team is looking at extracting REEs by using bacteria rather than toxic chemicals to separate metals from each other. Another area being explored as a safer option by researchers at Purdue University is to extract REEs from coal ash instead of mining for ores.
In the meantime, the unprecedented material properties of Rare Earth Elements are allowing for cutting-edge development of 21st Century technology.
Interested In REE Extraction Processes?
Then you may want to consider enrolling in EIT’s Graduate Certificate in Chemical and Process Engineering. This postgraduate qualification includes master's level units as part of the program and will enable you to gain an in-depth understanding of key concepts of thermodynamics, mass transfer, heat transfer principles, fluid transport phenomena, process dynamics, and control systems.
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Lieutenant Carl Axel Arrhenius:
Australia’s latest rare earth mines:
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