Something Useful from Acid Mine Drainage: Is that Possible?

By John McFerrin

One type of materials that is necessary for modern life is a class of minerals known as rare earth elements.  These elements are necessary components of modern technologies. They are used in cellular phones, computers, televisions, magnets, batteries, catalytic converters, defense applications and many more things that make modern life possible.  Now researchers at West Virginia University are working on a method to recover these rare earth elements from an unexpected source: acid mine drainage.

Rare earth elements are a type of elements with exotic sounding names such as terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium.  In spite of their name, they are really not all that rare.  They are not so common as elements such as silicon, carbon, or iron but they are still moderately plentiful.

The difficulty with obtaining them for use is that they are not concentrated.  They also only exist in nature bound up with other minerals.  There are no instances of old prospectors plucking up nuggets of erbium or movies of miners doing a happy dance when they strike a big terbium vein.  Such things do not exist.  Instead, extracting useable quantities of rare earth elements has always involved crushing large amounts of rocks in order to extract small amounts of rare earth elements.

Because the rare earth elements are not concentrated, the usual method of extracting them involved mining large amounts of rock, crushing it to a powder, and using several rounds of chemical processing to extract useable concentrations of rare earth elements.  The process produces rare earth elements along with a lot of waste.  Most of the current production is in China.  This makes its availability in the United States subject to all the uncertainty that comes from the United States’ relationship with China.

In a nutshell, rare earth elements are necessary to modern life but messy to mine and available mostly from foreign sources, subject to political uncertainty.  

Now researchers at West Virginia University are trying to solve the difficulty of the availability of rare earth elements by extracting them from one thing that West Virginia has plenty of: acid mine drainage and acid mine drainage sludge.

The acid water on mine sites has dissolved in it a wide variety of minerals.  If the mines are still active or there is someone taking responsibility for it, the water is directed into a pond or some other treatment facility.  There it is treated so that the minerals drop out and become sludge on the bottom of the facility.  The clean water flows to the stream.  If the mine is abandoned and no one is taking responsibility for it, the water flows to streams untreated.  The most visible result is the iron in the water, turning the stream and its bed orange.

Now researchers at the West Virginia Water Research Institute are developing a method to extract rare earth elements from both acid mine drainage and acid mine drainage sludge.

This is possible because the acid water had already done the first steps in concentrating the rare earth elements.  In most rare earth mining operations, the rare earth minerals are in such small concentrations that extracting a useable amount requires crushing a lot or rock and going through a multi-step refining process.  At coal mines, the acid water flows through the rock overburden, dissolving the rare earth elements along with the iron, aluminum, magnesium, etc. that are more visible.  Anyone seeking rare earth elements would still have to separate them from the iron, etc. in the sludge but that is much easier than starting with separating them from the rock.  Researchers are also working on extracting rare earth elements directly from the acid mine drainage, before it drops out of the water and becomes part of the sludge.

If this works, it would be a great thing.  Acid mine drainage is a chronic problem in West Virginia, one that the West Virginia Highlands Conservancy and other individuals and groups have spent decades begging, pleading, and suing in hopes of getting someone to address.  The main reason it has never been addressed is money.  Treatment of acid mine drainage is an expensive nuisance while the mining is going on.  Once the mining is over, it is an obligation to be gotten rid of if possible.  If the operator is not clever enough or unscrupulous enough to get rid of the obligation, it is a financial burden, begrudgingly taken care of.

Researchers who can figure out a way to turn these financial burdens into profitable rare earth extraction operations will be modern Rumpelstiltskins, spinning straw into gold. They could turn what is now a financially draining treatment obligation into something that at least breaks even.

Whether the West Virginia Water Research Institute can do this remains an open question.  So far, they have done it in the lab.  In the spring, they plan to open a demonstration project near Mt. Storm in West Virginia.  This may turn out to be an idea that makes a significant dent in our acid mine drainage problem while providing the United States with a domestic source of rare earth elements.  On the other hand, it may turn out to be one of those ideas that sounds good in theory but in practice never works as hoped for.  Babe Ruth went to the plate10,626 times in his career.  He hit 714 home runs.  He also struck out 1330 times.

The United States Department of Energy apparently believes that this idea has the potential to work.  The research so far has been funded largely by grants from the United States Department of Energy.  The recently passed Bipartisan Infrastructure Investments and Jobs Act authorizes one hundred and forty million dollars to study rare earth elements extraction.

Finders Keepers?  Or not?

Even if nobody knows for sure whether the technology for extracting rare earth elements from acid mine technology will work, there is already interest at the Legislature in clarifying who owns the minerals extracted.

Always before the owners of the mineral rights were only interested in mining the coal.  The minerals in the drainage were just something to get rid of.  When the iron was turning the creek red, it was all, “Oh, that’s not mine.  Must be somebody else’s iron.”  

Now that there might be valuable, extractable rare earth elements, the mineral owners will want to claim ownership.  Some who are interested in this technology have already appeared at interim Legislative meetings to suggest that the Legislature adopt legislation saying that whoever extracts the minerals from acid mine drainage gets to keep those minerals. There may well be a bill in the Legislature clarifying ownership of the minerals extracted from mine drainage.