NETL’s in-situ recovery (ISR) research is under development in order to potentially eliminate the need for large-scale earthmoving, blasting, or tunneling in the extraction of CMMs. Instead, reactive solutions are injected into the subsurface through existing wells to dissolve valuable minerals. The dissolved minerals, now present in the solution, are then pumped back to the surface for processing.

ISR technologies are often called “surgical mining” or “laparoscopic mining” because they represent a precise, data-driven approach that results in only a fraction of the environmental impact and capital expense compared to traditional mining methods.

“In laparoscopic surgery, small incisions and specialized equipment are used to achieve outcomes with minimal collateral damage and less trauma to surrounding tissue,” said NETL’s Christina Lopano, a research geochemist. “In the subsurface, ‘surgical’ or ‘laparoscopic’ mining could serve a similar function by selectively extracting critical materials while maintaining the competence of the surrounding rock.”

Such precision mining supports the U.S. Department of Energy’s Mine of the Future initiatives, which call for modernizing U.S. mining practices and reestablishing strong domestic supplies of CMMs to drive U.S. economic growth.

“Laparoscopic mining provides a remedy to supply U.S. manufacturers with CMMs to make everyday products like smartphones, laptops, and batteries, as well as complex energy and defense systems, and end our reliance on foreign nations who control CMM production,” said NETL’s Dustin Crandall, a research engineer.

Organic-rich shale formations, widely studied for hydraulic fracturing and oil and gas production, commonly contain elevated concentrations of trace metals and critical elements due to the geologic conditions under which they form.

NETL has conducted research on shale geochemistry and subsurface characterization for several decades, resulting in a substantial archive of datasets on subsurface physical and chemical properties. These datasets provide a unique opportunity to evaluate shale formations not only as hydrocarbon reservoirs but also as potential hosts for critical mineral resources.

“We are using that extensive body of knowledge about subsurface oil and gas recovery from unconventional shale formations to evaluate these systems for critical mineral resource potential and to develop novel CMM extraction scenarios,” Lopano said.

Potential surgical mining technologies that NETL is evaluating include:

• Enhanced geochemical extraction. Research will build on NETL’s previous experience with in-situ experimentation to explore the use of innovative reaction fluids for mineral recovery from sedimentary formations. Existing wellbores for oil and gas production may present an infrastructural opportunity to inject leaching solutions to dissolve target minerals and pump the solution to the surface.
• Microbial enhancements for dual-use hydraulic fracturing fluid development. This research will explore how biological processes may be engineered to facilitate the release of CMMs from subsurface fossil energy systems. NETL expertise in determining the microbial ecosystem of these subsurface systems will be leveraged to determine the best microbial pathways to target CMM release through biological means.
• Microwave stimulation to promote extraction. Microwaves can produce micro-cracks in the mineral structure, enabling the use of lower concentration of acids and leachates for recovery and providing enhanced recovery methods for natural gas, oil, and critical minerals. Research will evaluate the effect of subsurface conditions on the chemistry evolution and micro-crack propagation in different shale formations.
• Chelator/sorbent development to enhance extraction. A critical step in processing target CMMs from unconventional feedstocks typically involves leaching target metals from the solid state into solution followed by separation of the targeted metal from non-target metals. A material must be used that can selectively bind the target metal in the presence of significantly higher concentrations of non-target metals. Such a material is called a chelator, and its design is often tedious and costly. NETL will use its expertise in computational modeling and material design to experimentally validate the performance of chelator molecules toward different metals.

NETL is a U.S. Department of Energy (DOE) national laboratory dedicated to innovating and accelerating the nation’s energy solutions in hydrocarbons, geothermal energy, and critical minerals production. The Lab further strengthens its impact by engaging with industry, academia, and other stakeholders through four strategically located Centers of Excellence: Coal, Critical Minerals and Advanced Alloys, Oil & Gas, and Geothermal. With research sites in Albany, Oregon; Morgantown, West Virginia; and Pittsburgh, Pennsylvania, NETL operates as one laboratory to create advanced energy technologies that support DOE’s mission and enable affordable, reliable, and secure energy to fuel human prosperity.