Ramelius Resources (ASX:RMS) released an updated plan for its Mt. Magnet gold mine in Western Australia with a full mill over a 17-year period, producing 2.1 million ounces, according to a Tuesday Australian bourse filing.

The company said that all-in-sustaining costs (AISC) in the initial two and a half years of the plan will come in between AU$1,500 and AU$1,700 per ounce, with average AISC over the first 10 years of between AU$1,750 and AU$1,950 per ounce.

It expects to realize pre-tax cash flow generation over the plan of AU$2.5 billion at a gold price of AU$3,500 per ounce and AU$4.3 billion at AU$4,500 per ounce.

This includes a 680,000-ounce pit cutback at the Eridanus deposit to replace the earlier 280,000-ounce underground option.

It also includes AU$95 million upgrade for the Mt. Magnet mill to increase its throughput up to 3 million tonnes per annum, with construction, subject to board approval, planned for late 2026.

The firm's shares fell past 13% in early trading on Tuesday.