The study said the proposed US$450 million project yielded an after-tax net present value of $1 billion at an 8% discount rate and an internal rate of return of 24.2%, with an operating cost of $3,388/t and 5.4-year payback.

"The results … indicate that Pastos Grandes has the potential to be a robust lithium carbonate producer and be among the lower quartile of LCE (lithum carbonate equivalent) costs," said president and CEO Farhad Abasov in a statement.

"With a strong cash position Millennial is now confidently moving the project into the next development stage, including seeking full funding for construction."

Under the feasibility production scenario, brine would be pumped from up to 30 wells to evaporation ponds. A pre-production facility would remove magnesium and sulphate by precipitation through the addition of lime. When lithium concentrations reach 3%, the brine will be sent to a lithium carbonate plant where remaining trace impurities would be removed via solvent extraction, two phases of carbonation and ion exchange methods.

To ensure the operation produces as pure a product as possible, Millennial has included an additional purification stage using carbon dioxide to upgrade technical grade lithium carbonate to battery grade purity.

Millennial is assembling a three tonne per month pilot plant and building inventory through increasing the volume of concentrated lithium brine in its pilot evaporation ponds. The pilot plant will generate information to support detailed engineering estimates and product sample material for potential customers. 

Shares in Millennial Lithium (TSXV:ML) opened 8% higher at C$1.57, valuing the company at C$131 million. Its share price has increased about 27% so far this year.