Rare earth elements in the stainless steel industry

Rare earth elements

Jolanda Heunen - 23 April 2015

With names like ‘to lie hidden’ and ‘hard to get’, it’s not hard to guess where the designation rare earth elements stems from. But how are ‘rare earths’ used?

About the author

Ms Jolanda Heunen
Jolanda Heunen is Editor Print & Online for Managing Aging Plants and 3D fab+print. She is also Conference Coordinator for the Managing Aging Plants (MAP) Europe Conference.
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Recently Molycorp, Inc. was selected by Siemens AG to supply rare earth metals for the next ten years, in order to produce rare earth magnets that Siemens intends to use in its wind turbines. Now obviously these so called rare earths are very valuable, but what are they?

Elementally hard to get

The designation ‘Rare Earth Elements’ (REE) is not quite accurate, since the ‘rare earths’ are not so rare at all. Most REEs are actually abundant in nature, however, because they often lie hidden, extracting these precious elements can be a bit of a hassle and even hazardous.

Elemental elements

In our modern society the REEs are used in a multitude of fields, but before getting into some of the possible applications of the REE’s, let’s first have a quick look at the rare earth elements themselves. There are 17 rare earths in total, of which 15 elements belong to the chemical group called lanthanides and that have exotic sounding names like cerium, praseodymium, terbium, and samarium. The fifteen lanthanides are named after the first element in this series, lanthanum (to lie hidden), and scandium and yttrium make the list of seventeen REEs complete.

Mining the rare earths

So the rare earths aren’t rare, but this doesn’t imply that we have unrestricted access to these elements. Before the REEs – that can be found in the earth’s crust – can be used, they first need to be retrieved. China is currently both the dominant consumer and producer of REEs. China produces around 90% of the world’s rare earth needs, however, mining for the rare earths is increasing in other countries as well, like in the United States, but also in Mongolia and India. Now why are these little elements so valuable and wanted? Let’s have a look at some of the applications and find out.

rare earth metals

Steel production

In the production of several aluminium and iron alloys, the REE cerium is used. This element is quite abundant, which is of course good news for the producers of stainless steel, since it is also used as a precipitation hardening agent.

Technological products

In lots of devices that are used daily in our modern society, from smartphones to medical imaging equipment, one or more of the rare earth metals can be found. Specific REEs are used individually or in combination to make phosphors for example, that are used in flat panel displays and LED lighting.

Green products

Several clean energy technologies are expected to experience high growth in the years to come and the rare earths are needed to make this happen. Hybrid automobiles, next generation rechargeable batteries, biofuel catalysts, and wind turbines are just a few products that couldn’t exist without one or more of the REEs.

3D printing

The speed with which 3D-printing techniques are evolving is immense and also in this field do the rare earths appear. Ames Laboratory is for example working on a 3D-printer with which rare earth metals can be printed. In this way the otherwise hard to fabricate neodymium rare earth magnets can be easily printed.

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