rare earth elements

Rare Earth Elements

As is the case in so much manufacturing, China is now the world leader in the production of a class of elements known as rare earths. They are not actually rare in terms of relative abundance in the earth’s crust, Cerium for example is about as common as Copper. The rare part of the name comes from the fact that they are difficult to obtain because they generally don’t occur in high concentration deposits as do better known metallic elements such as Iron, Copper, and Nickel.

Where they are found, the ores occur in lower concentrations and because the various rare earth elements have very similar chemical properties, they are difficult to separate. This makes the processing all the more expensive. Seventeen elements constitute the group, the majority of which occur in the Lanthanide Series of elements.

Although they share much of their chemical properties, each has unique uses especially in electronics and other modern high tech products.

One of the more common is Neodymium (Nd, atomic number 60.) It confers hardness and unique optical properties when used in small amounts as a dopant in glass. This glass is then used in the manufacture of certain kinds of lasers. Nd is also used in an alloy for high strength permanent magnets. Neodymium magnets have the advantage of having a high magnetic field strength to weight ratio. Applications include loud speakers, in-ear headphones and computer disks.

Several of the rare earths were first discovered in Ytterby, a small town in Sweden,. Yttrium (Y no. 39), Ytterbium (Yb 70), Erbium (Er 68), and Terbium (Tb 65) all take their name from the same mine

As noted many modern devices utilize rare earths – electronics, magnets, lasers, batteries, and efficient lightning just to name a few. An obvious modern device loaded with rare earths is a hybrid car. About 28 kilograms (~ 62 pounds) of rare earths go into a hybrid car. That is only a small fraction compared to the total weight, but it is a very important fraction.

Another now ubiquitous device, the cell phone, is chock full of rare earths. The glass is harder, and the speakers and memory are lighter, and the vibrating motors stronger – all due the rare earths.

So what’s the big deal about rare earths? The big deal is that currently China controls 97% of the market on these elements which are so important to modern society and even more importantly to a modern military. Our military is dependent on a foreign power for a strategic material. There are exploitable deposits of rare earths in the United States, but are not mined because of costs.

Efforts are being made to bring the cost of mining and processing of the rare earths down which could make our sources more attractive. That said, applying the same techniques to the richer Chinese deposits will make their materials correspondingly cheaper also.

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