Last Thursday, August 1, Polymetals Resources (ASX:POL) announced that it had completed the purchase of the Endeavor silver-lead-zinc mine near Cobar, in western NSW. On Monday, it revealed that it hadn't been standing still, unveiling mining plans that had obviously been put together in the knowledge that the deal would go through.

Polymetals said its mine plan was "significantly improved" to exploit the silver-lead-zinc resources at the Endeavour mine, with the aim of starting mining in the first half of 2025.

Costing around $28 million to $30 million, with a payback period of just 14 months, the company aims to begin production in the first half of 2025, following the finalisation of a $30 million debt facility.

The plan forecasts production over 10 years of a total of 260,000 tonnes of zinc, 10.6 million ounces of silver, and 90,000 tonnes of lead.

The plan has a pre-tax net present value (NPV) of $414 million and an internal rate of return (IRR) of 345%. It anticipates a pre-tax free cash flow of $609 million, generating an annual EBITDA (earnings before interest, taxes, depreciation, and amortisation) of $89 million in the first five years.

The company said the plan "demonstrates that the project will generate outstanding financial returns and create substantial value for Polymetals shareholders and the Cobar Region; with significant increases in Ore Reserves, Mine Production, Free Cashflow, Net Present Value (NPV), and Internal Rate of Return (IRR) compared to the MRS."

Polymetals' executive chair Dave Sproule said the results of the mine restart were impressive.

"In addition to this great value, we are also moving to test several ideas to unlock contained gold and silver from the existing stored tailings using hydrometallurgical techniques, and we are actively engaged in exploration to expand the mineral resource of the deposit to extend mine life.

"The quality of the Endeavor mine asset, our Cobar Basin operational familiarity, the significant remaining metal endowment, and enormous exploration potential, provide a platform for substantive and long-term returns for our shareholders and the region."

Polymetals says it has already commenced critical path site refurbishment activities, including upgrades to underground infrastructure. It is also actively exploring near-mine areas, with further drilling at the Carpark prospect underway.

This mine plan is linked to the deal the company did with nearby Metals Acquisition Corp (MAC) which owns the Cobar copper operation.

As part of that deal, MAC invested in the $6.2 million issue run by Poly to help with the funding of the development. MAC invested in the issue to keep its shareholding to 4.3% for a total investment in Poly of $5 million. The two companies have entered into an agreement to treat high-grade ore at the Endeavor mine, and Poly will provide MAC with access to water offtake for use at the CSA mine at Cobar.

The issue was done at 28 cents, and the shares ended at that level in the miserable day on the market, tucking away a gain of 8% on a day that saw the ASX lose 3.7%.