Rare Earth Elements: perhaps not everyone knows that …

By Chiara Bonomi

Figure 1 Periodic Table: Rare Earth Elements (REEs) [1]

What are REEs?

Rare earths are a group of seventeen elements of the periodic table (figure 1). Fifteen of these elements belong to the group of lanthanides (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium), whereas the other two are yttrium and scandium, which have similar chemical and physical properties to lanthanides and they tend to exist in the same ore deposits as the lanthanides.

Why are REEs important?

Perhaps not everyone knows that rare earths are nearly everywhere in our daily life (figure 2). When we go for a walk during night in our cities, make a call with our smartphone or relax in front of the television, even when we watch a football match at the stadium, unknowingly we are handling a large amount of rare earths.

The list of things that contain Rare Earth Elements (REEs) is almost endless. In fact, because of their exceptional magnetic, luminescent, electrochemical and catalytic properties, these elements are essential to modern technologies.

Magnets made with REEs are much more powerful than conventional magnets and weigh less; that's one reason so many electronic devices have gotten so small. The red colour in our LCD TVs comes from europium [1]. Our smartphones contain rare earths (e.g. an iPhone contains eight rare earths). Although the amount of rare earths in each phone is very small, the quantity of phones sold each year is impressive. According to Apple, in 2012 over 125 million iPhones were sold worldwide, up from 72 million in 2011 [2]. Also digital cameras contain REEs: the electronic circuit board has magnets in it that include neodymium, samarium and many other rare earths; lenses are made from a special glass that has lanthanum or lutetium in it, so that the images have no distortion; europium and terbium make the display look colourful [3].

REEs are also used in street lights, energy-efficient light bulbs and high-intensity lighting in sports stadiums. They help improve intensity and colour balance.

 

Figure 2: Source USGS

Figure 2 (Source USGS)

Can we talk about “RARE” metals?

Karl Axel Arrhenius discovered REEs in 1787 in a quarry near Ytterby (Sweden). Johann Gadolin misleadingly suggested the term “rare earths” in 1794: “rare” because, when the first REEs were discovered, he thought that they were present only in small amounts in the Earth’s crust, and “earths” because, as oxides, REEs have an earthy appearance [4].

Despite on their name, REEs are not rare. In fact the more abundant REEs are each similar in Earth’s crust concentration to other metals such as chromium, nickel, copper, zinc, molybdenum, tin, tungsten, or lead. Even the two least abundant REEs (Tm, Lu) are nearly 200 times more common than gold [5] (figure 3).

Figure 3 Relative abundance of the chemical elements in Earth's upper continental crust [5]

However, REEs are difficult to mine because they occur together with other mineral ores (the most feasible ores for REEs extraction are bastnasite, xenotime, and monazite) [6].

European initiative and Critical Raw Materials

With the increasing on demand and prices and with Europe depending entirely on imports (China has been producing approximately 85% of the world's supply), REEs provision has become more difficult.

For these reasons, in 2010 the European Commission, taking into account both their economic importance and the supply risk, published a list of 14 materials defined “critical”.

 

Figure 4 List of EU 20 Critical Raw Materials, 2013 [7]

The list was revised and extended in 2013, where twenty Critical Raw Materials (CRM) were determined. As we can observe from figure 4, REEs are the most CRM.

This analysis is within the EU Raw Materials Initiative (RMI), promoted in 2008 to contrast the monopoly of some countries on strategic raw materials and based on three pillars:

  1. Sustainable mining
  2. Recycling (supply of secondary raw materials from “urban mining”)
  3. Substitution of critical raw materials

 

Ensuring sustainable access to these raw materials is crucial to the competitiveness and growth of the EU economy and to the objectives of the Europe 2020 strategy [8].

 

 

 

[1] http://ngm.nationalgeographic.com/2011/06/rare-earth-elements/folger-text/1

[2] http://www.rareelementresources.com/rare-earth-elements/rare-earth-elements;

[3] http://humantouchofchemistry.com/history.php?action=view&nid=691

[4] Massari S. and Ruberti M. Rare earth elements as critical raw materials: focus on international markets and future strategies. Resource Policy 38 (2013) 36-43;

[5] http://pubs.usgs.gov/fs/2002/fs087-02/;

[6] Rare Earth Elements: A Review of Production, Processing, Recycling, and Associated Environmental Issues, EPA 2012. http://nepis.epa.gov/Adobe/PDF/P100EUBC.pdf;

[7] REPORT ON CRITICAL RAW MATERIALS FOR THE EU: Report of the Ad hoc Working Group on defining critical raw materials, May 2014. EU Commission.

[8] The raw materials initiative : meeting our critical needs for growth and jobs in Europe, 2008;