By Bengi Yağmurlu
Technology is evolving at a speed which no one can track. As a result, for every new product and for every piece of research, new opportunities with new demands are arising. Certainly, advances in materials and their processing are among these demands. Lots of research and lots of effort is being spent to improve the properties of current materials or producing new types of materials with better specifications. For this purpose “uncommon” elements are preferred due to the undiscovered areas and properties they offer. What is the term “uncommon” referring to? I mean literally “uncommon” elements, the ones which are not commonly found in the earth’s crust, i.e. elements that are lacking in the crust or that are rare; “rare earth elements (REEs)”. From a scientific point of view, these elements are the ones in the lanthanide group, scandium and yttrium. These elements cannot be found in every place or every mine. In fact, the majority of them aren’t directly mined, but occur as a co-product of another material, this is another reason why they are classified as “rare”.
We are living in a time where we hear “rare earth elements” frequently in newspapers, journals and even in daily conversations. All of us are using these elements without being aware that we are using them. Smartphones, computers, TVs and even headphones and microphones, medical imaging and especially all of the kinds of vehicles that we are using in our daily life are some of the commonly used areas of these REEs. These areas are starting to become addicted to these elements, so the demand for them is increasing rapidly and the shortage of them is the main reason that they make the headlines. Lots of colleges, institutes and universities try to design these elements out of new materials that they are developing because of the insufficiency of these elements and the political attitudes of governments that have opportunity to produce REEs, however; the properties that they impart to the materials cannot be surpassed by anything else at the moment. And the one which is rapidly increasing in popularity among them is scandium.
Among all REEs, scandium is the cool guy in the class, that’s one reason why it is popular right now. It holds the title “lightest REE”. Also, it considered to be new on the scene; the application areas were only developed in mid 1970s. After that time, a new era began in the field of aluminium alloys. As is known from history, aluminium has always a great impact in technological developments because as weight decreases, handling becomes much easier. The discovery of Duralumin and its use in aircrafts is one of the most important examples of this claim. However, aluminium alloys also have their own problems, as all materials have: insufficient mechanical properties and manufacturing difficulties are at the head of this list. It was found that the addition of small amounts of scandium were the remedy for the majority of them. Use of scandium in aircraft is believed to decrease the total weight of these craft by 15-20%. Unfortunately, using scandium containing alloys almost doubled or tripled the productions costs, so their use was limited to some specially purposed parts. As a result, titanium is preferred as a replacement of scandium to decrease the expenditure while sacrificing these advanced properties.
However, in this age, humankind started to discover the skies and above. Only last month, Pluto was reached for the first time and first high resolution image was taken; a planet analogue to earth, Kepler-186f, was discovered in Kepler system; and also space mining projects are in the pipeline. Space is much more reachable now and these advances are altering our perception. Another important advance in the air is the return of the supersonic aeroplanes for both business jets and passenger planes. After Concorde accident, companies took their time to make their design flawless, while eliminating the problems of this plane (i.e. high noise generation) and just last week, Airbus announced that they have patented a new design for supersonic planes. With these advances, there will be opportunities and for some parts, one cannot ignore the advantages of Al-Sc alloys. Moreover, scandium has one of the leading roles in these advances now and then.
As might be expected, as this research progressed, the demand for, and therefore the price of scandium also increased. While the price of one kilogram of scandium oxide was US$1300 in 2003, now you can only purchase 200 grams for same price in 2015. Similarly, the gram price of high purity (99.9%) scandium ingot has changed from US$110 to US$200 which means it doubled its value in 10 years. So, if the production rate will continue at the same rate, one can say that the value will continue to follow the same trend. It is predicted that the demand for scandium will rise to 450 tonnes per year while the current global market is between 2-15 tonnes per year. To eliminate this shortfall, lots of initiatives have been started to recover this valuable element.
Bauxite residue is one of the most significant recovery sources of scandium. While the earth’s crust contains on average 20 ppm of scandium, this waste material of alumina production contains 130 ppm. These might not seem like worthy numbers, however when the global bauxite residue stocks are considered, which is of the degree of several megatons, this source can be predicted to be larger than all of the current scandium sources combined. So, this is one of our aims as the ETN-MSCA REDMUD team. With increased recovery of scandium, the prices for it will fall for certain and new areas and opportunities will definitely be on the agenda. These applications will vary from transportation vehicles to solid-oxide fuel cells, from 3D-printing and even wiring applications. So it is obvious that there is a future ahead of us with plenty of scandium in it.
 http://www.scandiummining.com/i/pdf/Scandium-White-PaperEMC-Website-June-2014-.pdf http://www.nasa.gov/ames/kepler/kepler-186f-the-first-earth-size-planet-in-the-habitable-zone http://www.independent.co.uk/news/science/asteroid-worth-35-trillion-set-to-pass-earth-on-sunday-and-you-can-watch-it-live-10398708.html http://www.theguardian.com/business/2015/aug/05/airbus-patents-hypersonic-plane-paris-tokyo-three-hours http://minerals.usgs.gov/minerals/pubs/commodity/scandium/ http://www.scandiummining.com/s/presentations.asp