365 Days of Climate Awareness 315 – China and Rare Earths

The rare earth elements, also known as REEs, rare earth metals or rare earth oxides, are a chemical class of metallic elements known as the lanthanides (plus two others, scandium and yttrium, also in column 3 of the periodic table of elements). The lanthanides are so named due to their similar behavior to lanthanum. In the periodic table, they are the upper row in the subset usually drawn beneath the rest of the chart (drawn this way to keep the chart from being too wide for the page). As in the illustration in this post, the lanthanide series slips in between lanthanum (atomic number 57) and halfnium (72). There are seventeen rare earth elements/lanthanides, and they are critical for much of our developing renewable energy technology. (For a more detailed list of each element and its uses, please refer to the Wikipedia article.)

Periodic table of the elements, standard view

Periodic table, lanthanides and actinides shown in series

Rare earths are not uncommon in Earth’s crust, ranging between 150-220 parts per million (ppm) and one, cerium, being more common than copper (though promethium, a radioactive metal with a half-life of 17.7 years, is in fact extremely rare). The “rare” moniker comes from the fact that these elements are not found in concentrated deposits like most metals such as iron, uranium or gold. When present, they are distributed very sparsely, though several different rare earth elements are often found together (likely due to the similarity in their chemical behaviors). REEs are found both in crustal rock and in the regolith, the weathered sediment lying on top of crustal (bed-) rock.

Global rare earth production.

Rare earth mining in the regolith (sedimentary layer).

Rare-earth elements have several applications in renewable energy technologies (not including photovoltaic cells, which might surprise you). Their main applications are in specialized magnets, as specialized alloys (metallic blends, either as a mixture or a chemical compound), chemical catalysts, and as polishing compounds, and others even more particular. The typical method of mining these is by open pit, where tons of rock are transported to a plant and the REEs are chemically isolated and concentrated. It is a tremendously energy-intensive process which leaves massive scars on the planet surface. There is also the problem of disposing of the waste, the leftovers from chemical solutions used to extract the REEs.

Industrial applications for rare earth elements.

Global rare earth market share through the years.

China has 50% of the world’s currently known deposits of these elements, and is the source of nearly 90% of global production (nearly 150,000 metric tons/165,000 tons in 2019). Since rare earth elements are considered strategic—being hard to find and impossible to replace—China’s overwhelming market position is considered a hazard by governments and markets around the world. Research is underway both to make REE extraction methods less environmentally destructive and to circumvent use of those elements altogether.

Rare earth strip mine in China.

Tomorrow: Global carbon emissions.

Be brave, and be well.