Elk Creek demo plant recovers magnesium-calcium carbonate with 99% purity.

As an initial step toward the ultimate goal of producing niobium, rare earths, scandium, and titanium at a future Elk Creek Mine, NioCorp Developments Ltd. announced that its demonstration-scale processing plant in Quebec, Canada has produced a high-grade calcium-magnesium carbonate from ore obtained from its critical minerals project in Nebraska.

The idea behind removing the calcium and magnesium from Elk Creek ore as the first step of the recovery process is to get these bulky and less valuable materials out of the way in order to make it more efficient to produce the targeted critical minerals during the second and third phases.

The deposit at Elk Creek is what is known as a carbonatite, which means that carbonate minerals make up the bulk of the ore that will be mined.

Removing calcium and magnesium carbonates with thermal treatment and leaching is a common first step for plants processing ore from deposits like the one at Elk Creek. So, it is no surprise that the recovery process and demonstration plant designed by L3 Process Development and NioCorp starts with this time-tested initial step.

The mixed calcium-magnesium carbonate produced from Elk Creek ore run through the demonstration plant, however, is 99% pure. So, instead of needing to handle this as waste, NioCorp could have another saleable product that could cover some of the costs of producing the targeted critical minerals.

Selling these essential minerals was something that was not previously considered, and a resource was never calculated for them. Given the purity of the calcium-magnesium product coming out of the first phase of the demonstration plant, however, NioCorp plans to investigate the potential of adding these two elements to the resource and recovering them as an essential mineral byproduct to the critical minerals Elk Creek is known for.

Three-phase process

The removal of calcium and magnesium from Elk Creek ore is the first step of a three-phase critical minerals recovery process being demonstrated at the pilot plant in Quebec, which is expected to be scaled up to a commercial-scale processing facility at Elk Creek.

During the second phase, a leaching process will be employed on the remaining material to produce niobium and titanium. The third phase will test the technical viability of separating high-purity versions of several target magnetic rare earth products and scandium from Elk Creek ore samples.

NioCorp had not previously considered the recovery of rare earths in its plans for Elk Creek.

A feasibility study completed earlier this year detailed plans for a mine at Elk Creek that would produce roughly 170,400 metric tons of niobium, 431,800 metric tons of titanium, and 3,680 metric tons of scandium over 38 years of mining.

A calculation completed in May, however, shows that the same Elk Creek deposit considered in the feasibility study also hosts 632,900 metric tons of total rare earths.

Given this abundance of rare earths and the enormous demand for these elements used in clean energy and other technologies, NioCorp decided to test the potential of recovering them alongside the niobium, titanium, and scandium.

The company is particularly interested in the production of neodymium-praseodymium oxide, dysprosium oxide, and terbium oxide due to their rocketing demand for use in the powerful permanent magnets going into electric vehicle motors, wind turbine generators, and other high-tech and consumer goods.

"The updated feasibility study shows that the Elk Creek deposit contains an abundance of critical minerals, including rare earths, and we are working very hard to ensure America can benefit from the full range of the critical minerals our deposit could economically deliver," NioCorp Developments CEO Mark Smith said in May.

Potential economic benefits

While continuing to demonstrate the phase-one removal of calcium and magnesium, L3 will begin ramping up the phase-two and phase-three processes in parallel.

L3 has carried out extensive metallurgical testing of Elk Creek ore, including bench-scale testing of the processes being scaled up at the demonstration plant in Quebec.

NioCorp Developments Ltd.

A furnace for thermal treatment of Elk Creek ore at the L3-designed critical minerals recovery demonstration plant.

"Many of these processes have already been successfully tested at the bench scale. Given our team's years of experience in hydrometallurgy, including rare earth separations, I expect that we will demonstrate positive results," NioCorp Developments Chief Operating Officer Scott Honan said in September.

NioCorp plans to incorporate the results from the demonstration plant into an updated feasibility study that adds rare earths to critical minerals produced at a future Elk Creek mine, as well as a simpler process for recovering the niobium, titanium, and scandium also found at the Nebraska critical minerals project. A process that may enjoy a small economic boost from the calcium and magnesium also produced.

"We look forward to the completion of the remainder of the demonstration plant operations, and most importantly, the rare earth metallurgical performance metrics showing the full potential economic benefits of rare earths for the Elk Creek Project," said Honan.