West Virginia University (WVU) researchers are opening a new facility to capture valuable materials from a novel source—acid mine drainage from coal mining—turning the unwanted waste into critical components used in today’s technology-driven society.
Through a collaborative research and development program with the National Energy Technology Laboratory, part of the U.S. Department of Energy, WVU is opening the Rare Earth Extraction Facility to bolster domestic supplies of rare earths, reduce the environmental impact of coal-mining operations, reduce production costs and increase efficiency for processing market-ready rare earths.
Additionally, the technology could create jobs, helping to revive economies that have been historically dependent on the coal industry.
“Research on rare-earth extraction is one way that our university is fulfilling its most important mission—which is the land grant mission—to advance the prosperity of the people of this state,” President Gordon Gee says.
Representatives from WVU, NETL, DOE, West Virginia’s congressional delegation and others gathered July 18 in the High Bay Research Lab at the WVU Energy Institute’s National Research Center for Coal and Energy on campus to tour the new Rare Earth Extraction Facility and mark the start of this new phase of research.
Brian Andson, director of the WVU Energy Institute, hosted the event and conveyed statements of support from the members of the state’s congressional delegation, including Rep. David McKinley and Sens. Joe Manchin and Shelley Moore Capito.
In addition, WVU welcomed keynote speaker Steven Winberg, DOE assistant secretary for fossil energy.
“It’s a pleasure to be in West Virginia, because West Virginians understand what it really means to have an ‘all-of-the-above’ energy strategy,” he said at the event.
WVU is partnering with Rockwell Automation to facilitate market readiness through use of their sensor and control technologies in the new WVU facility.
Paul McRoberts, regional industry mining, metals and cement manager at Rockwell Automation, a 30-year veteran of the industry, said that this is one of the most exciting projects he has been a part of during his career and is excited to see the results of the new facility.
The facility is the researchers’ phase two project, worth $3.38 million, funded by NETL with substantial matching funding from WVU’s private sector partners. It follows on an earlier, phase one project, worth $937,000, to study acid mine drainage as feedstock for rare-earth extraction. The goal of the pilot facility is to test the technical and economic feasibility of scaling-up the technology to commercialize the separation and extraction process.
In addition, the team will be working to define a U.S.-based supply chain including the sludges created during acid mine drainage treatment and upstream to the acid-mine drainage source.
Neither rare nor earth
The name “rare earth elements” is a misnomer for important chemical elements that are actually neither rare nor earths.
A collection of 16 elements that hang off the bottom of the periodic table, they are moderately abundant but well dispersed in the Earth’s crust. They are identified as rare because it is unusual to find them in large concentrations.
The elements are all metals that carry very similar properties. In rare cases they are found in deposits together. Unlike an element such as gold, natural rare earth deposits never occur as pure metals, but are bonded in low-value minerals, making extraction challenging.
Conventional rare-earth recovery methods require an expensive, difficult and messy extraction process that generates large volumes of contaminated waste. China has been able to provide a low-cost supply of rare earths using these methods and, therefore, dominates the global market.
The conventional mining and extraction processes require mining ore from mineral deposits in rock, which is crushed into a powder, dissolved in powerful chemical solutions and filtered. The process is repeated multiple times to retrieve rare earth oxides. Additional processing and refining separate the oxides from their tight bonds and further groups them into light rare earths and heavy rare earths.
In usable form, 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 segments of modern society.
Paul Ziemkiewicz, director of the West Virginia Water Research Institute and principal investigator on the project, is an expert in acid mine drainage. He found that acid mine drainage, a byproduct of coal mining, “naturally” concentrates rare earths. Active coal mines, and in many cases state agencies, are required to treat the waste, which in turn, yields solids that are enriched in rare earth elements.
“Acid mine drainage from abandoned mines is the biggest industrial pollution source in Appalachian streams, and it turns out that these huge volumes of waste are essentially pre-processed and serve as good rare earth feedstock,” Ziemkiewicz says. “Coal contains all of the rare earth elements, but it has a substantial amount of the heavy rare earths that are particularly valuable.”
Studies show that the Appalachian basin could produce 800 tons of rare earth elements per year, approximately the amount the defense industry would need.
“Currently, acid-mine-drainage treatment is a liability, an environmental obligation,” Ziemkiewicz says. “But it could turn into a revenue stream, incentivizing treatment and creating economic opportunity for the region.”
Ziemkiewicz; Xingbo Liu, professor of mechanical engineering in the Statler College of Engineering and Mineral Resources; and Aaron Noble, associate professor of mining and minerals engineering at Virginia Tech, have designed the processing facility from the ground up using advanced separation technologies. Chris Vass, PE, is the operator of the new facility and a Summersville, W.V., native.
The researchers are using a two-step process to separate the rare earths from acid mine drainage: acid leaching and solvent extraction, which they call ALSX.
Researchers will dissolve the sludge in an acid. That solution will then be transferred to glass mixers and settlers that will make an emulsion that allows the oil phase and its extractant chemical to grab rare earths from the water, leaving the non-rare earth base metals like iron in the water
When that process is completed, the rare-earth-laden organic liquid enters another series of mixers and settlers that will strip the rare earths out as a concentrated solution and precipitate the rare earths as a solid, creating a concentrated rare earth oxide that can then be refined and further concentrated into pure rare-earth metals to supply the metal-refining industry.
The goal of the project is to produce three grams of rare earth concentrate per hour.
“For example, scandium, one of these rare earths, is worth about $4,500 per kilogram as an oxide, the form that it will leave this facility,” Anderson says. “After refining, it would be worth $15,000 per kilogram.”
Unused materials will be returned to the acid mine drainage treatment plant’s disposal system, resulting in a negligible environmental footprint.
“This process uses an existing waste product that is abundant in our region,” Ziemkiewicz says. “It is also much easier to extract and requires much milder acids and has negligible waste materials when compared to conventional rare-earth recovery methods.”
A team, led by John Adams, assistant director of business operations at the WVU Energy Institute, is also defining the supply chain, moving upstream to the source and working with coal-industry partners. By producing a purified product at the mine, researchers could reduce transportation and waste handling costs.
“This could go a long way toward creating new economic opportunity for West Virginia and the region and make treating acid mine drainage a financial boon instead of a financial burden,” Anderson says.
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