An updated preliminary economic assessment (PEA) for Rockhaven Resources’ (TSXV: RK) wholly owned Klaza gold project in the Dawson Range gold belt outlines a 12-year, combined open-pit and underground operation producing gold and silver doré as well as lead and zinc concentrates.
With total payable metals production of 750,000 oz. gold and 13.8 million oz. silver over 12 years at all-in sustaining costs (AIScs) of US$875 per gold-equivalent oz., the after-tax net present value for the project comes in at $378 million, at a 5% discount rate.
Based on an average plant throughput of 1,900-tonnes per day, open pit mining at the site would start in the first year of operations for a three-year period, whereas the underground portion would operate over the 12-year life of the combined mine. The initial capital costs would be $244 million.
“This study demonstrates that Rockhaven’s Klaza deposit could support a mine with a long life and robust economics,” Matt Turner, the company’s president and CEO, said in a news release. “Since the last economic study was completed in 2016, closer spaced drilling has better defined the upper portions of the deposit, resulting in higher average grades in a superior resource category.”
Turner added that, based on the results of the PEA, Rockhaven is now looking to advance Klaza towards a pre-feasibility level alongside continued drilling targeting new discoveries.
The proposed processing flowsheet includes crushing, grinding and milling of the mineralized material, followed by a conventional flotation process to generate lead, zinc and arsenopyrite concentrate that would be treated with an on-site, 250 tonne per day pressure oxidation (Pox) circuit. Precious metals would also be leached from the zinc and lead concentrates.
In the release, Rockhaven emphasizes the exploration upside at Klaza, as the PEA evaluates the mining of three (out of eleven) known zones of mineralization.
Indicated resources at Klaza stand at 4.5 million tonnes grading 4.8 grams gold per tonne, 98 grams silver per tonne, 0.7% lead and 0.9% zinc, containing a total of 907,000 gold-equivalent ounces.
Additional inferred resources total 5.7 million tonnes at 2.8 grams gold, 76 grams silver, 0.6% lead and 0.7% zinc, for a further 725,000 oz. gold-equivalent. The pit-constrained portion is based on a 1 gram gold-equivalent cut-off grade, whereas the underground component is derived using a 2.3 grams gold-equivalent cut-off.
The 11 known zones of mineralization at the road-accessible Klaza property cover a combined strike length of over 10 kilometres. These are within a 1.8-km wide corridor, where low to intermediate sulphidation veins feature gold, silver, zinc and lead mineralization.
— This article first appeared in the Canadian Mining Journal. The Northern Miner and the Canadian Mining Journal are part of Glacier Resource Innovation Group.