Chicago—Researchers at Pacific Northwest National Laboratory (PNNL) have found that injecting organic molecules into underground rock formations could unlock US critical mineral reserves unreachable by conventional mining. Nabajit Lahiri presented the findings Monday at the American Chemical Society Fall 2026 meeting in a joint session of the Division of Environmental Chemistry and the Division of Geochemistry.
Nickel, cobalt, and manganese are essential for batteries in electric vehicles and energy storage. Though the US has large underground reserves, these metals are too dilute for economic recovery. In ultramafic rocks found throughout Earth’s crust, nickel, cobalt, and manganese are typically present at concentrations of around 3,000 parts per million—a concentration far below what conventional mining can profitably recover by moving rock.
“Instead of moving mountains of rock, we use the earth as a chemical reactor,” Lahiri said. The team injects fluids through wells to selectively dissolve and recover the metals, reducing surface impact.
This in-situ mining method is common for uranium and copper but typically uses sulfuric acid, which dissolves rock without distinguishing between metals and requires extensive processing to separate them. The acid also poses risks to groundwater.
The PNNL team uses chelating agents, such as EDTA (ethylenediaminetetraacetic acid) and 1,3-PDTA (1,3-propanediaminetetraacetic acid), organic molecules that selectively attach to specific metal ions through multiple chemical bonds; the molecules wrap around the ion to form a stable complex that stays dissolved in solution. Selectivity comes from the molecule’s geometry: different chelating agents are shaped to grip different metal ions, and the ones used in this work target nickel, cobalt, and manganese. “They are also biodegradable and can be recycled after extraction,” Lahiri said.
The team reported that adding carbon dioxide to the injected fluid further improves selectivity. The CO2 forms carbonates with iron, calcium, and aluminum, which precipitate and remain underground. Meanwhile, nickel, cobalt, and manganese remain dissolved as stable complexes with the chelating agents. The complexes exit with the extracted fluid. This process traps unwanted minerals and doubles as a carbon capture method.
The team recovered 90% of the nickel from the sample and trapped over 60% of injected CO2 in the rock.
From these results, Lahiri’s team extrapolated that by applying this method to 1 km3 of rock in the Twin Sisters Formation, an ultramafic deposit in Washington State, they could recover 500,000 metric tons of nickel when 5% of the rock is reacted. That is roughly 30 times what the US produces annually from its only operating nickel mine.
Other researchers at the conference said the chelation chemistry was a novel and promising concept but raised questions about reaching those scales. Theis Solling, a researcher at King Fahd University of Petroleum and Minerals, said the challenge is the physical structure of the rock: injected fluid can contact minerals only along fracture surfaces rather than throughout the formation. “You need to dissolve as much rock as you want to extract,” Solling said. “Getting fluid into contact with even 5% of such a formation would be quite challenging and would need extensive drilling or fracking.”
Lahiri said the process also generates hydrogen. “From one cubic kilometer of rock, we could generate enough hydrogen to power 1 million homes,” he said. But Solling is skeptical of these numbers.
The technology received an R&D 100 Award this year, an annual recognition given to 100 technologies judged among the most significant innovations, and the team has filed multiple patents. Field demonstration is the next step. “This is a technology in transition,” Lahiri said. “We have shown that it works. Now we’re in the process of taking this to the next step.”
