The ore originated from the Elk Creek critical minerals project in Nebraska, while the demonstration plant is located in Quebec.

The project flow sheet for the demonstration plant was designed by L3 Process Innovation, with NioCorp. The production of calcium and magnesium marks a key Phase 1 milestone, NioCorp said.

The demonstration plant uses thermal treatment and leaching to remove calcium and magnesium carbonates as part of its Phase I. The calcium and magnesium were produced at demonstration scale as a mixed calcium and magnesium carbonate.

The calcium and magnesium samples produced through this process produced a mixed calcium-magnesium carbonate of an overall 99% purity, NioCorp said.

Removing the metals in this way is expected to reduce the size of following production steps, NioCorp said.

NioCorp will continue testwork and assembly of Phase II and Phase III of the demonstration plant's planned operations in parallel to continuing Phase I calcination ramp-up. NioCorp will also ramp up leaching operations for Phase I.

The Elk Creek resource is a carbonatite, with mineral resources comprised of predominantly carbonate materials. It is the highest-grade niobium project in North America, NioCorp said.

In addition to niobium, NioCorp plans to produce scandium trioxide and titanium dioxide from Elk Creek.