Gallery Description
Digging In The Desert Molycorp’s rare-earths mine is located about an hour southwest of Las Vegas in Mountain Pass, Calif. The mine has been in operation for 60 years except for the years 2002–07. The pit is 600 feet deep and 3/4 of a mile wide. The tiny dark rectangles on the upper-right edge of the pit are the 70-ton trucks used to bring lanthanide-series-containing ores up from the mine to be separated. Credit: Melody Bomgardner/C&EN
Hot Topics The Molycorp tour included customers, investors, policy-makers, and even competitors. Some international visitors came to learn how to set up rare-earth mines in their home countries. Credit: Melody Bomgardner/C&EN
Containing Waste This looks like a flat desert plain, but it is part of Molycorp’s initiative to run the mine with strong environmental safeguards. Designed to hold dewatered cakes of waste material, called tailings, the area has two protective linings to prevent seepage. Only about 8% of ore mined at the site is valuable rare earths—the rest of the material is waste. Credit: Melody Bomgardner/C&EN
Getting The Rare Out Ores containing about 8% of rare earths—including lanthanum, cerium, neodymium, and praseodymium—are taken to these buildings where they are crushed and then milled into a powder. In the first phase of processing, the powder is put into water, and the portion containing rare earths float to the top. Credit: Melody Bomgardner/C&EN
Starting Small Molycorp estimates that its mine contains about 1.5 million tons of rare-earth oxides. But the facility produces the oxides a little at a time. Visitors saw this modest-sized pile of ore waiting to enter the first processing stage. Credit: Melody Bomgardner/C&EN
Self-sufficiency The Molycorp facility has much in common with an integrated chemical manufacturing site. Here, visitors saw the company’s chlor-alkali facility, which produces hydrochloric acid used to dissolve rare-earth materials present in the rock. Molycorp also operates its own natural-gas-based heat and power plant. Credit: Melody Bomgardner/C&EN
Visitor From The Past Wild burros, likely the descendants of a much-earlier era of mining, roam the Molycorp site. They may be attracted by the availability of fresh water, which is piped in as part of the mine’s operations. Credit: Mason Haneline/Molycorp
One View, Many Stages This view of the many processing buildings at the Mountain Pass site shows that obtaining rare earths is a capital- and energy-intensive process. The buildings house solvent extraction, separation, and product-finishing operations; water treatment facilities; brine storage; and the power plant. Credit: Melody Bomgardner/C&EN
Materials For Magnets The final stop is where a mixture of neodymium and praseodymium ores is prepared to ship to Molycorp’s Magnequench facility in Tianjin, China. There, the NdPr is processed into powders used to make strong permanent magnets for equipment including electric motors. Credit: Melody Bomgardner/C&EN