Page 7

COAL ASH COLD CASH? Duke University researchers explain that key components of technologies such as smart phones and electric car batteries include rare earth elements, which are found in abundance on the micro level in fly ash (FA) ponds near Duke University in North Carolina.

Helen Hsu-Kim is an environmental engineering professor at Duke University and together her team study the materials that make up FA from regions throughout the United States. FA is held in ponds or in above ground landfills at fourteen (14) power plants throughout North Carolina. Although rare earth metal extraction technology has increased ten fold in the past decade, Dawn Santoianni, a spokeswoman for Duke Energy believes the metal extraction technology is just not ready for FA on a large scale. The U.S. Department of Energy and the Electric Power Research Institute (EPRI) on the other hand are both prompting efforts to extract metals from FA. EPRI representative Ken Ladwig, claims that the increasing value of the rare earth elements has renewed interest in mining FA at the Institute. EPRI is looking at how leaching FA metals can be done in large quantities. Technologies that could make the FA mining process workable at a factory scale will be determined by early 2017. Hsu-Kim explains that rare earth elements are not actually “rare”, just hard to find in high enough quantities in order to be profitable. In fact, they are found in very low quantities in almost any material. Hsu-Kim’s student, Ross Taggart believes that the rare earth elements and other metals are actually encased in glass pellets [amorphous structures] found throughout FA. He believes you must first get through the glass to extract the [rare earth elements] metal. Duke researchers do this by dissolving and leaching the FA in acids, which separates the glass from the metal in the lab. When government proposals of digging up FA ponds in North Carolina, Taggart stated, “If you have to excavate it anyway, you can do something with it.” The Department of Energy is collaborating with Hsu-Kim and her students to isolate each of the 15 rare earth elements after they are separated from the FA. Filters that can separate these elements by size and magnetic properties are being developed however the elements are very similar in size so it will take time to perfect a method to screen for a single element. [In the US] around 45 percent of FA today is being used to make concrete and roadways. Ladwig and Hsu-Kim both believe that [after] leaching FA for [rare earth elements] metals the residual material could be used as a building material. Through the Ash Development Association of Australia international partnerships and alliances will attempt to keep our readers at the forefront of Duke University’s progress with [rare earth element] metals extraction. Read more:



Coal Ash Matters - November 2016  

Launched in late 1996, Coal Ash Matters (CAM) is a biannual publication produced by the Ash Development Association of Australia and its mem...