Corvus Gold has announced the results of a preliminary economic assessment (PEA) for its Mother Lode project (MLP) in southwest Nevada, USA.

The study outlines a project able to produce 170,980 oz/y of gold and 79,600 oz/y of silver through a combination of heap leaching and biological oxidation (BIOX).

Based off measured and indicated resources of 1.55 Moz of gold and 1.51 Moz of silver, and inferred resources of 170,000 oz of gold and 400,000 oz of silver, the study estimated an operation with an eight-year mine life and an initial price tag of $406 million. Using a $1,500/oz gold price, the payback period was estimated at 2.7 years.

Jeffrey Pontius, President and CEO of Corvus, said: “The results from our initial PEA study of the Mother Lode standalone project are encouraging. The potential projected annual gold production of over 200,000 oz/y during the first three years is significant, especially as a new project, which could provide an increase to the Corvus Gold future production profile. The PEA demonstrates the preliminary potential for the project, on its own, to produce significant free cash flow and after-tax NPV.

“Corvus now has a number of strategic alternatives available to it to drive shareholder value. Given the recent interest in the Bullfrog Gold District from multiple producing companies with adjacent land packages, Corvus’ compelling and accretive projects and its commanding land position with what we believe is demonstrated high exploration potential, has positioned the company to deliver increased shareholder value.”

The Mother Lode project is modelled as a large, open pit, with a biological oxidation mill to treat the higher-grade sulphide mineralisation and a heap leach pad for treatment of oxide mineralisation. The mining plan uses standard mining practices and has a production scale that is currently being used by many operating mines, the company said.

The new PEA study, which assumes a standalone project, also includes a number of other changes to the previously assumed concept for the combined Mother Lode-North Bullfrog project configuration, which enhance the project. This includes:

• Employing BIOX to treat the MLP sulphide mineralisation would increase gold recovery by 11%. Metallurgical testing of a stirred BIOX process on the MLP whole sulphide mineralisation from Mother Lode demonstrated gold recoveries of 91-92% as compared with the previous testing on MLP flotation concentrate;
• Eliminating the need for the concentrator, oxygen plant and autoclave components of the previous plant concept simplified the plant conceptual design and would reduce the process plant capital cost;
• Ongoing work expanding Mother Lode resources in the CIZ area and the main Zone with ongoing work at improving the open-pit mining and development plans will enhance project economics; and
• New experimental work on conducting the BIOX process in a heap is being tested as follow-up on past successful studies and could substantially cut operation and capital costs with the elimination of the mill circuit.

The PEA only includes drill results completed up until September 2020. In addition, Corvus will continue follow-up mineral resource expansion work and new discovery drilling on priority targets at both the North Bullfrog and Mother Lode properties through 2021, it said.