Rare earth elements (REEs) are necessary for the development and manufacture of high-tech devices like personal computers, cell phones, and even national defense systems. Traditionally, rare earths
have been mined from mineral ores, then refined and separated. However, NETL is finding a way to answer the growing demand for REEs by devising ways to harvest them from one of the nation’s most abundant natural resources – coal.
For more than a century, coal has reliably and affordably fueled the nation, enabling unprecedented gains in the quality of life for generations. Now, NETL is investigating whether this same plentiful domestic resource could economically yield yet another wide-ranging benefit – a domestic supply of REEs. Rare earths are found in coal, coal mining byproducts, and coal preparation residues, making every step in the coal mining process a potential source of REEs.
Producing rare earths at home is important because the Unites States currently imports most or all its supply from other countries, and this foreign reliance creates vulnerabilities when overseas markets shift unpredictably.
NETL REE Technology Manager Mary Anne Alvin explained that, “As a U.S. Department of Energy national laboratory, NETL initiated its Rare Earth Elements Program in 2014 to address the feasibility of extracting and separating REEs from coal and coal byproducts including fly ash, coal refuse, and acid mine drainage.”
NETL’s overarching goals are to develop extraction and separation technologies that can lead to the economic and efficient domestic production of rare earths from coal-based resources. First up in that process is an effort to validate the technical and economic feasibility of prototype systems to produce high-purity, salable, REEs by 2020.
NETL, along with external stakeholders, are using a comprehensive cost-benefit analysis approach to determine whether REEs can be separated and recovered from coal- based feedstocks economically. The process involves development and implementation of techno-economic analysis models to evaluate the international REE market and then assess the economics of commercially producing REEs from existing conventional, novel, advanced, and potentially transformational separation and recovery processes.
Morgan Summers, an NETL engineer and economic analyst, emphasized the importance of techno-economic analyses.
“Applying techno-economic analysis to the early stages of these design concepts will improve the chances for economic success by making researchers not only ask how
we can recover rare earths from coal- based materials but also, how can we do it economically to compete in the global rare earth market,” he said.
More economic uncertainty exists for projects in early development because of an emphasis on process performance rather than process economics. Highlighting economics early in the development phase will raise awareness of the economic impacts associated with design decisions. Analysts have determined that driving down operating expenses will have a bigger impact on reducing required revenues than lowering capital costs. Evaluations have indicated that operating costs far exceeded an annualized capital cost, on a per ton of product produced basis. This further emphasizes the need to make sound design decisions early in the development process.
Techno-economic analyses help researchers understand the cost and performance of REE concentration and separation from various feedstocks. Once this is understood,
specific research and development for the extraction of REEs from coal feedstocks can be identified and more aggressively pursued. Additionally, techno-economic analysis allows for the evaluation of the economic benefits of conventional, as well as transformational separation processes that are being developed within the REE supply chain.
NETL is incorporating the techno-economic analysis approach into process designs for currently funded REE separation and recovery projects.Atitscore,techno-economicanalysis modeling orients and helps direct research efforts to ensure that researchers are aware of the economics of their processes as early in the design phase as possible. That awareness allows adjustments to be made in designs prior to scale-up. That way, if economic hurdles exist with a design, mitigation strategies or design changes can be implemented early in the development process to help advance commercial readiness without attempting major design changes after the process system is physically built.
NETL’s multi-faceted research is helping to establish a reliable domestic supply of rare earths, focusing on many various stages of REE recovery from coal and coal- based products including field sampling, characterization, extraction and separation, and small pilot-scale REE production.
Currently, the U.S. uses over 17 thousand tons of REEs each year. That demand could be completely met by extracting rare earths from domestic coal and coal byproducts. Considering that coal contains 62 parts per million (ppm) of total rare earths on a whole sample basis, and there are more than 275 billion tons of coal reserves in the United States, then 17 million tons of REEs are present within the domestic supply of coal.
Clays and shales located above and below coal seams are also potential sources because they can contain around 200 ppm or more total rare earths. In the United States, burning coal for power generation and industrial uses typically produces around 75 million tons of post-combustion coal fly ash annually, which typically contains more than 400 ppm of total REEs.
NETL Research Engineer Evan Granite said, “By tapping into this vast untouched resource of coal and coal byproducts, the United States could benefit from a 1,000-year supply of REEs at the current rate of consumption.”
NETL has developed techniques for characterizing samples in its REE research. In fact, more than 800 field samples have been collected as part of its research since June 30, 2015, by NETL researchers and personnel from the U.S. Department of Energy’s Office of Fossil Energy.
NETL has used a variety of techniques to
advance its REE characterization work. For example, by improving the methodology for inductively coupled plasma mass spectrometry, researchers have increased the accuracy of determining levels of trace REE concentrations.
Strategic Research Partnerships to Accelerate REE Research
In FY16 – FY17, Congressional language specified that REE Program objectives should include external agency activities for development and testing of commercially viable, advanced separations technologies at proof-of-concept or pilot-scale stages. The initiative called for near-term deployment of innovations enabling the extraction and recovery of rare earths from U.S. coal and coal byproduct sources with the highest potential for success.
NETL Federal Project Manager Charles Miller explained that, “These strategic partnerships amplify NETL’s contribution toward recovering
NETL’s Dr. Ronhong Lin performing particle size reduction of coal samples in a ball mill to release rare earth minerals from coal.
The increased activity surrounding sample characterization work has sparked additional interest in the public and private sector. The United States Geological Survey and the Electric Power Research Institute have both signed memorandums of agreement with NETL calling for additional collaborative research and sampling activity.
After determining which REEs are present and in what quantities, the next step in the process involves selection, development, and progressive improvement of extraction and separation techniques. NETL is developing these capabilities for use with resources such as pre-combustion coal, coal refuse, clay and sandstone over or under burden materials, aqueous effluents, and power generation post-combustion ash.
NETL expertise in computer modeling also plays a key role in critical REE research. The Laboratory has developed advanced computation fluid dynamics (CFD) software
to simulate REE separation and optimize the separation process. CFD models serve as virtual test platforms that allow researchers to optimize process separation designs.
REEs from domestic coal and coal-based products. The technology developed through this work could help maintain jobs in the coal industry and improve national security by developing a domestic supply of REEs.”
In 2017, the DOE-NETL REE Program portfolio consisted of 15 active REE technology development projects that are working toward these goals. In 2018, the DOE-NETL REE portfolio will expand to approximately 30 active projects, including efforts with universities, small businesses, and other national laboratories.
NETL manages five external service contracts that began in October 2016 to identify promising sources of domestic coal and coal byproducts containing high REE concentrations. The University of Kentucky, West Virginia University, and XLight Corporation are undertaking one project each while Tetra Tech Inc. leads two projects. These projects consist of work to identify, locate, field sample, and analyze REE- bearing materials from various regions of the country including material from the Illinois Coal Basin, Northern Appalachian Coal Basin in Pennsylvania and West Virginia, Central Appalachian Coal Basin in West Virginia, and the Raton Basin in Colorado and New Mexico.
One additional NETL external contract to identify and characterize domestic coal and coal byproducts started in October 2017. The University of North Dakota was awarded a two-year contract to sample and characterize a variety of U.S. coal-based resources containing high concentrations of rare earths. The university will also perform a round- robin interlaboratory study on the analytical methods used to measure the concentration of REEs in U.S. coal-based resources.
Additionally, NETL manages four projects that are developing bench-scale and pilot-scale technologies to economically extract and concentrate mixed REEs from coal and coal byproducts, including aqueous effluents. Each is making noteworthy progress in developing high-performance, economically viable, and environmentally benign technologies to recover REEs from domestic coal and coal byproducts. For instance, during Phase 1 of the four projects, external partners achieved a production of ? 2 percent by weight REE pre-concentrate from coal-based materials – a key step toward securing a domestic supply of rare earths. They also developed a project- specific REE recovery system design that will be developed and tested in Phase 2. All four projects will enter Phase 2 by January 2018 and will finish by 2020.
Bench-scale projects include work by the University of North Dakota Institute for Energy Studies, which is using North Dakota lignite and coal-related material as feedstock to test their REE recovery system; and the West Virginia University Research Corporation, which is using acid mine drainage solids from Northern Appalachian and Central Appalachian bituminous coal seams as a feedstock for recovery of REEs and other useful materials.
Pilot-scale projects include work by Physical Sciences Inc., which is using coal fly ash physically processed near Trapp, Kentucky, as a feedstock, and The University of Kentucky Research Foundation, which is using two sources of coal preparation byproducts (tailings) as feedstock for recovery of REEs.
In addition to the four external projects described above, NETL further expanded strategic research partnerships by supporting two new projects that will develop a Phase 1 system design for small pilot-scale production of salable REE products in the form of individual rare earth compounds with a minimum purity of 90 percent.
Inventure Renewables and Marshall Miller & Associates will each lead one of these projects. These Phase 1 salable REE projects began in September 2017 and will compete for a Phase 2 award that will require the development, testing, and operation of the project-specific design that was developed during Phase 1. It’s anticipated that one or more Phase 2 salable REE projects will be awarded and begin by mid-2019 with completion expected in 2020.
Aside from the active projects, NETL recently selected under a competitive Funding Opportunity Announcement, nine new external R&D projects for negotiation and award of advanced REE recovery technology at laboratory/bench-scale, to start in late 2017 and finish in 2019.
In describing the future of REE research at NETL, Mary Anne Alvin said, “as the REE program continues, first- and second- generation REE extraction and separation systems will address processing requirements for a broad portfolio of coal-based feedstock materials, as well as enhanced REE and mineral production efficiency, and validation of small pilot-scale systems to technically and economically produce high-purity REE oxides by 2020.”
Mary Anne Alvin
Mary Anne Alvin works in NETL’s Science & Technology Strategic Plans & Programs directorate, Efficient Resource Development Team. She joined the Lab in 2005, and is currently the Rare Earth Element Technology Manager, responsible for validating the technical and economic feasibility for separation and recovery of salable, high purity, rare earth elements from domestic coal-based resources in conventional, prototype, and advanced operating systems.