Ash to Dust

Years ago there was a proposal by a power company to place a fly ash dump site along Seminole Highway in the then Town of Fitchburg, Dane County, WI. A high end residential subdivision put an end to their hopes. So too, did the coming recycling of waste. Fly ash is a waste product of coal fired power plants. According to Professor Ross Taggart et al, the U.S. currently generates over one-third of its electricity from coal, which in turn produces a large amount of coal combustion products. Times have changed since that power plant proposed the fly ash dump site, most particularly about 45% of fly ash is now recycled, much into concrete or other building materials. Yet, that leaves the majority unrecycled. Fly ash is composed of toxic trace elements which pose concern for ground and surface water contamination. The Duke Energy Dan River Station saw a large toxic spill in 2014. But, this toxic waste also holds valuable rare earth elements (RREs). Researchers are now looking for ways to obtain REEs from the fly ash of power plants, for which there are good reasons, and it is more than just the ability to recycle.

Rare Earth Mineral Movement

To recycle, a product needs a demand, and while REEs are not so much rare in not much around, it is that they are rare because they are found in low quantities and often difficult to process out of other material. As Taggart explains, these elements are not found in nature as a pure metals, but they must be isolated from host material. Rare earth elements occupy, according to a Reuters report, 15 entries on the periodic table. Rare earths often are found with uranium and thorium, two elements which pose their own set of issues. The refining process requires a great deal of acids, which too need to be disposed of. China has 97% of the market on REE, and coupled with little regulation by that communist state, they need not worry about the pollution caused, or the death from cancer and other diseases due to their methods of extracting the RREs. I like to say that China in terms of enviornmental regulation is where the U.S. was during the Gilded age. Environmental regulation adds cost, and is one reason why the main mine in the United States has been in and out of business, even though demand for REEs have never been greater. An Australian Company has proposed mining the material in their home country, but processing it in Malaysia. Externalizing negative effects of mining (in this case processing) and other undesirable land uses is a common trend of first world countries. There are other reasons China poses a concern. If there is any question of China wanting to control the market of material, you just need to look at the mineral rights they are buying in Africa and South America. If there is any question of their expanding their sphere of influence look at what they are doing in the South China Sea, of which they see the whole area as part of their own manifest destiny. We oppose mines in our back yard, but still expect the products that result from the mining activity. We need copper, we need iron ore, and we need the RREs.

REEs ina Smartphone

Rare earth elements are more common in most products of today than we think. Our high technology products increase the demand for the REEs. As an article in Mother Jones pointed out several years ago, “Walk down the aisle of your local Best Buy and you would be hard-pressed to find something that doesn’t contain at least one of the rare earths, from smartphones to laptop batteries to flat-screen TV’s." They are also used in products for defense—radar, sonar, and bomb navigation systems. They clean the air of our cars, by their use in catalytic converters. Even in trying to be green REEs are present--think wind turbines. Then their is the Toyota Prius. Jack Lifton, an independent commodities consultant in strategic metals was quoted in a Reuters article saying that the Prius is “the biggest user of rare earths of any object in the world.” The article noted that each Prius motor requires 2.2 lbs of neodymium and each battery 22 to 33 lbs of lanthanum. It goes on to say that the number will probably double as Toyota attempts to improve the Prius’ fuel economy.

Uses of REEs

Chinas’ monopolization of the market is of obvious concern to the U.S. With China producing 97% of the REEs on the earth, and the U.S. having only about 15% of the total world supply, one can see that this poses a concern. The high tech aspects of the defense industry require REEs. Toyota understands the Chinese dominance and is looking at accessing rare earth mines in Vietnam and Canada. The U.S. knows it but is looking at other measures besides mining. The United States Department of Energy is spending about $20 million dollars to research extraction technologies for coal waste. A professor at Duke University says that coal ash contains “literally billions of dollars’ worth of rare earth elements.” This follows the conclusion of the May 2016 paper by Taggart et. al, which, in its last paragraph says that “More attention is needed for improved methods of extraction and recovery.” It notes that economic feasibility and environmental responsibility of coal ash as an alternative to REE will hinge on the development of these extraction technologies. Of course, coal ash begins with some benefits. First, the location of coal ash deposits is known; second, it is readily available; third, it does require extensive excavation (which, as noted in the Taggart article is costly and environmentally damaging), and in so doing avoids uranium and thorium; and finally, it is a fine powder, which is easy to process. Aluminum and a few other elements are already recovered from fly ash. Appalachia is thought to contain the coal deposits with the highest levels of REEs. But, the method of recovery is not one-size-fits all. The specific chemistry of each type of coal ash will affect the method and chemicals used to undertake the reclamation. Small test projects are not necessarily cost effective on an industrial scale.

Periodic Table of the Elements

In a sense the Prius is not as green as it may first appear. A Prius driver may think they are doing well environmentally. However, first world, and sometimes environmentally smug, Prius drivers likely do not think of the environmental damage occurring to obtain such high levels of rare minerals far away in China, Malaysia, or even here in the United States. While Toyota is looking for other sources, and perhaps studying ways to use other material in-lieu of REEs, the United States is looking to solve the problem by turning waste into something precious, and which may even benefit power companies by recovering the rare earth materials from fly ash. Ash to dust, may be the solution to the nation’s rare earth elements.

Production of Rare Earth Elements

Scientific source: Taggart, Ross K., James Hower, Gary Dwyer and Heileen Hsu-Kim. “Trends in the Rare Earth Element Content of U.S. Based Coal Combustion Fly Ashes”. Environmental Science & Technology. 13 May 2016.

Images from Google