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Exactly when REEs will start coming out of the ground in Idaho is an open question. The claims were announced only this summer and testing has begun in earnest. Once the results come back, and if they show a substantial quantity, the next step will be test drilling and a long process to determine just how large the reserve is. After that, it's a matter of securing the necessary permits. It's a process that could take years.
"All these deposits, at least at the surface, are showing good numbers," said James Hedrick, who worked as a rare earths specialist for the U.S. Geological Survey for 31 years and now serves on the advisory boards for both U.S. Rare Earths and Colorado Rare Earths. "You never know until you drill it. Until you drill it, you can't take it to the bank."
There has been interest in Idaho's REE potential for decades, though it piqued after a December 2010 report by the U.S. Department of Energy ranked the Lemhi Pass deposit near the top of domestic reserves and among the richest in the world. According to estimates in the report, the Lemhi area contains 15 REEs ranging from the "light" lanthanum to the "medium" samarium to the "heavy" yttrium.
Potential reserves of cerium in the Lemhi Pass area could top 19 percent of total worldwide rare earth oxides, while its store of neodymium could account for 18 percent and its ytrrium up to 20 percent.
All of these elements play foundational roles in a vast array of technologies, though one form of cerium oxide is especially prized for its use as a catalytic converter to reduce carbon dioxide emissions from vehicles.
Cerium alloys are also used in permanent magnets--like those needed for computer hard drives and mobile devices--but neodymium magnets hold the distinction of being the strongest permanent magnets known.
One of neodymium's central uses is in electricity generators for wind turbines and hybrid and electric vehicles. According to industry data, each Toyota Prius that rolls off the line requires just more than 2 pounds of neodymium.
Virginia Gillerman is an economic geologist, associate research geologist and resident rare earths expert with the Idaho Geological Survey. She has been working on a study of Idaho's REE potential, and in a recent GeoNote paper stated that Idaho's geologic makeup hosts the nation's largest reserve of thorium, a naturally radioactive element that often occurs with a corresponding abundance of REEs. In fact, the search for thorium, useful in nuclear science and, potentially, power generation, is what led Idaho Power, the Atomic Energy Commission and the U.S. Geological Survey to examine the Lemhi Pass area in the first place.
"In particular, the thorium veins in the Lemhi Pass area have long been recognized as a major thorium and rare earth resource but without any real defined numbers associated with them," Gillerman said. "While we know there's a lot of rock up there that's enriched with these elements, we don't know if it's enough or economical to mine."
The economics of rare earth mining are tricky. Prices for processed REEs--referred to as oxides--have increased fourfold this year as China announced in April it would cut back its output from an average annual 100,000 tons to 93,000 tons. Hedrick said the profits could be huge, with prices potentially headed toward the $300-$400 per pound range.
But the up-front costs are also huge. Depending on the type and quantity of resource, REEs can be extracted with open pit or underground mining. The biggest costs, though, come with the facility needed to extract and separate the REEs from their surrounding ore bodies.
The process includes dissolving the concentrate in a strong acid or a base to convert it into a solution. Adjusting the ph will shear off the rare earth cerium, and the rest of the other elements are extracted using kerosene or diesel fuel as a stripping agent. That causes the REEs to come out as a solid, which is then put into an open furnace where it turns into a rare earth oxide. It generally takes between six and 18 months to get the product out.
Solvent extraction plants, Gillerman said, are "basically chemical plants," and Hedrick said that they rely on basic, known technology but can cost anywhere from $200 million to $500 million to build. Full build-out of a rare earth mine--including the mine itself--can total between $300 million and $700 million.
"You don't get a cash flow for six months to a year ... but when you get it, it's going to be consistent and big-dollar," Hedrick said. "Once you do some drilling and it has good results, then the money will really start flowing."
But thorium poses a problem. The radioactive element has to be separated from the REEs during the extraction process and either disposed of or stored.
In China, the processing of REEs has led to dramatic and widespread environmental damage. Farmers in Inner Mongolia, which is home to several enormous REE mines, have been dispossessed by poisoned water supplies, and the vast lakes of toxic slurry, brimming with radioactive waste, are thought by many to be disasters waiting to happen.
Indeed, ecological concerns were given as a primary reason for China's curtailment of its REE exports--an average of 6 percent per year over the past five years--but most industry watchers maintain that China is holding back exports so it can fuel its own industrial development.
In Idaho, rare earth mining is still largely under the radar for conservation groups. When contacted about the potential for REE mining in the Lemhi Pass area, representatives of the Friends of the Clearwater--which watchdogs the nearby Frank Church-River of No Return Wilderness--said that "that's the first we've heard of it."
Gillerman agreed that thorium disposal or storage is the primary environmental concern with REE mining, but "it's really no worse than a lot of other industrial processes."
"It's a lot trickier than with a gold deposit," she said. "It depends a lot on the particular property and the level of radioactivity at the form. At best, it's expensive. You're not allowed to just dump it down the drain like they might do in some places or throw it in an unlined pond like they might do in Mongolia."