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DOMESTIC MINING - MOUNTAIN PASS MINE REOPENS

BY HAROLD HOUGH

The United States, which was once the world leader in the mining of rare earths, hasn’t produced any since 2002. However, that is changing. In September, operations commenced at the Mountain Pass Mine and are expected to produce around 10 million pounds of rare earths in 2008. Mountain Pass is the world’s largest developed deposit mined exclusively for rare earths. Rare Earth Elements (REE) are relatively unknown to the average person. With a few names such as europium, praseodymium, neodymium, lanthanum, samarium, cerium and gadolinium rarely get mentioned in chemistry classes, much less normal conversation. Although called “Rare Earths,” they are abundant in the Earth’s crust. It was the fact that they were hard to extract and purify that led early scientists to think they were rare. Before World War Two, the world’s supply of many of these elements was measured in grams and merely laboratory curiosities. And, the lack of samples guaranteed that scientists didn’t spend much time studying their properties.

The growth in electronics in the post WW II age changed all that. Today REEs are critical for optics and electronics. Europium, for instance provides the red phosphor in color cathode-ray tubes and liquid crystal displays used in computers and televisions. There is no known substitute. And, the powerful magnets made with neodymium are critical for many miniaturized electronics, including high capacity disk drives and DVD players. Even your outdoor grill relies upon cerium to light the propane.

For years, the United States was self sufficient in the mining of REE thanks to the Mountain Pass deposits that were discovered in the 1949. Two prospectors were looking for uranium deposits, when their Geiger counter detected high radioactivity in a rock outcropping. The prospectors staked a claim and sent off ore samples. When the assay results came back, they discovered that they had discovered a worthless mineral called bastnaesite. The claims ended up in the hands of MolyCorp after the USGS carried out additional surveys in the 1950s.

Mountain Pass was developed at a critical time. By the 1960s color televisions were finding their way into every American household and europium was critical for their television tubes. As the mine developed more efficient solvent extraction processes to extract europium, they produced in turn more REEs, which allowed scientists to find new uses for them. Many of these new applications were in defense industries.

For the next generation, Mountain Pass was the major source for rare earths for the world. However the increased demand for them caused geologists to find new deposits for them, especially in China, which soon became the major rare earth producer. By 2000, 90% of all the REEs used in the US came from China. Currently, the US uses about $1 billion in REEs a year. But, China wasn’t just a rare earth producer. It has also focused on finding new applications for REEs and is now a rare earth technology leader. REEs are critical to several defense technologies and American military leaders are uncomfortable with China’s lead in this critical technology.

Unfortunately, environmental policies around the world made it easier for China to take the REE lead. Mountain Pass’s solvent extraction process had created wastewater problems and regulatory issues forced the mine to reduce production. By 2000, they stopped mining and two years later, they stopped processing the stockpiled ore. Other countries have also had problems with mining and processing REE. Monazite is the most common REE mineral, but it contains thorium, a radioactive material. During the extraction process, the thorium and other radioactive materials like radium accumulate and create a hazard. Consequently, monazite mines began to close down around the world. This gave a boost to non-radioactive REE deposits like those found in Mountain Pass.

The Mountain Pass startup is modest according to Scott Honan, the HES Manager. Stockpiled ore will be used to produce two products – lanthanum concentrate and didymium (75% neodymium and 25% praseodymium). The goal for these first two years is to make sure the mine can produce a consistent, high quality product at competitive prices. If the program is successful, the plan is to expand operations and begin mining the bastnasite ore. Chevron Mining, which owns the mine, has obtained a 30-year mining permit from the county. If the economics allow, the company is prepared to significantly expand the operation. In 2002, the last year that Mountain Pass operated, it provided 46% of the nation’s REE needs. According to the USGS 2007 Mineral Commodities Summary, depending on demand, Mountain Pass could easily cut our REE imports by 50% in 2008. And, larger operations could push that back further. The US may not become the world leader in REE mining again, but it will have a secure domestic source once again.