Time To Face The Thorium

Rare earth oxides, clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium and gadolinium. Image courtesy of Peggy Greb, Agricultural Research Service, US Department of Agriculture.

By XiaoZhi Lim
BU News Service

Love your smartphone that delivers clear sound and bright colors but still fits in your pocket? Give thanks to neodymium, a rare earth element that makes the magnets in your phone so powerful that it can be as small as it is. Wind turbines and electric cars need the unique magnetic properties of dysprosium, another rare earth element. Virtually every form of clean energy technology today needs rare earth elements to function.

But the rare earth elements come with an unavoidable by-product: thorium. Thorium, named after the Norse god of thunder, is a mildly radioactive element. Digging up rare earths creates thorium waste, a huge liability for the mining industry. And because only China tolerates thorium’s environmental hazards in storage and disposal, ninety-seven percent of all the rare earth elements that we need come from China. Yet, we don’t have to cede rare earth production to China: the rare earth elements can be mined and produced domestically if we safely dispose of or even find uses for thorium.

Rare earth elements, a group of seventeen metals, are essential in the manufacture of devices ranging from cars to wind turbines to laptops.  These elements contain special magnetic, electronic and optical properties found nowhere else in the periodic table. For example, gadolinium has  magnetic properties for enhancing MRI images; dysprosium is critical for miniaturizing while helping permanent magnets remain strong and magnetic; yttrium improves fuel efficiency in vehicles and reduces pollution, and europium oxide produces a bright red color in television and computer screens. Take away those seventeen metals and the technological world as we know it becomes slower, bulkier and massively crippled.

The term ‘rare’ is a misnomer: rare earth metals can be found scattered in small amounts all over the world. The extraction of each of the pure elements involves extremely tedious, repetitive steps with costly chemicals, which is why they are deemed ‘rare.’ To reach those elements, one has to work past thorium; in fact, detecting the weak radiation from thorium is a method used to find the metals.

In the mid-1960s to 80s, Mountain Pass mine in California, owned by Molycorp Minerals, was one of the largest supplier of rare earth elements for the world. The company was forced to cease production in 2002 because of thorium-contaminated wastewater and competition from China. Over the last three decades, almost every other country has wound down its rare earth production, while China expanded the industry on every front, from academic research to industrial processing techniques.

China’s dominance of rare earth production comes with a price. Radioactive wastewater and thorium-tainted tailings have found their way into the Yellow River and Yellow Sea, polluting a water source for some 150 million people. China’s monopoly on the global rare earth supply also threatens the security of the global rare earth supply. During a dispute with Japan in 2010, China withheld dysprosium, a crucial rare earth element to the Japanese technology industry. The move destabilized the rare earth market as prices skyrocketed. China has also forced companies like Magnequench, General Electric and Ford Motors to relocate some factories, if not entire businesses, to China.

In March 2012,  the United States, European Union and Japan filed a challenge with the World Trade Organization against China for unfair restraints on exports of rare earth elements. The solution, however, is not to blame China, but to mine the rare earths domestically and find ways to handle thorium. Last year, Molycorp Minerals reopened the Mountain Pass mine, using modern methods to minimize thorium pollution, such as mixing solid tailings with concrete and recycling wastewater in a closed-loop system. But as more and more rare earth is produced, there will be even more thorium to process.

Another solution would be to put thorium to good use in nuclear power generating emissions-free energy. In recent years nuclear power experts have advocated taking a new look at a power generating system that can run on thorium fuel, an inherently safer technology than conventional fission reactors. The Oak Ridge National Laboratory successfully tested a molten-salt reactor for three years beginning in 1965, but President Richard Nixon de-funded the program because it did not produce weapons-grade uranium and plutonium.

Some may argue that nuclear power is not viable; that and we should stick with the true renewables like solar and wind energy. Yet those and other renewable technologies depend on rare earth elements. When we find uses for thorium, not only do we eliminate a waste problem, we can help technology move towards a cleaner and more secure future.

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