Rare earth element mining is a tantalizing venture.Rare earths are not rare in the strict sense, as they are wildlydistributed around the globe and their industrial uses requirerelatively small amounts of finished oxide. It may come as a surprise tolearn that some of the rare earths are more abundant than copper,cadmium, lead and platinum. And yet the prices for small amounts of thevaluable elements are going through the roof. Finding rare earths, andextracting the minerals in which they are distributed, is no moredifficult than any other form of resource mining. But separating theelements into usable ores and metals has proved to be much more complexand expensive and has essentially stopped a headlong rush intorare-earth mining.

Rare earth elementsare found in a variety of minerals, although most are found inbastnaesite and monazite; the former containing mostly light rare earthelements with small quantities of heavies while the latter containslight and higher concentrations of heavy.

The largest bastnaesite deposits are found in Chinaand the US, although known deposits exist in sites as widespread asCanada, Russia, Malawi and Norway.  Monazite deposits are found inAustralia, Brazil, China, India, South Africa, South East Asia and SriLanka.

Expertise and commitment the key

To separate rare earth elements safely and effectively is a long,complex and expensive exercise, which demands a great deal of expertiseand commitment to the process.  There are currently very few operationsoutside of Chinathat have the knowledge to carry out the process of extracting rareearth elements from ore and very few facilities and plants with theinfrastructure in place to begin.

“The ability to process is very, very critical and very, very complex”
Mark Smith of Molycorp
’5th International Rare Earths Conference’ Hong Kong, 2009

Producing rare earth oxides is considerably harder than other mining processes. Extracting gold metal from ore, for example, is relatively easy. Mix gold ore with sodium cyanide and the gold metal is leached out.

Conversely, rare-earth element extraction involves many steps. In thecase of bastnaesite, usually found in igneous rock formations, the oreis mined using traditional open-pit techniques. The bastnaesite is thenremoved from the rock by crushing the ore into a small gravel, and thengrinding the crushed ore in a mill until it becomes a fine sand. Thatsand, or silt, gradually separates into different mineral grains —bastnaesite and other generally less valuable minerals. The silt is thenrun through a floatation process wherein a liquid element is added, andair bubbles introduced. The finer bastnaesite silt sticks to thebubbles and rises to the top of the liquid where it is skimmed off.ⁱ

That is the first process. The bastnaesite must now be separated intoits constituent rare earth elements. The mineral is usually sent to aseparation plant where each element is separated using an acid orsolvent extraction process.

To read the rest of this article, please head over to Kidela.com: Mining is the easy bit: Separating rare earth elements is where the complexity comes in