PC Gold (ASX:PC2) has achieved up to 99.4% gold extraction from weathered material at its Spring Hill Gold Project in the Northern Territory, using a coarser grind than previously considered.
Six composite samples representing oxide, transitional, and fresh mineralisation were tested by Bureau Veritas (EPA:BVI) under the guidance of Strategic Metallurgy for the project’s Prefeasibility Study (PFS).
Two weathered composites returned 99.4% extraction at a P80 grind size of 150 micrometres, meaning 80% of the material passed that size. PC Gold says further testing will assess whether similar results can be maintained at even coarser grind sizes.
Fresh material returned overall extraction rates of 90.2–98.7% at P80 grind sizes of 106–150 micrometres. Gravity gold recovery across all samples ranged from 33.1–48.9%, with leaching used to recover the remaining gold.
Executive Chair Ashley Pattison says the results indicate the oxide material liberates at a substantially coarser size than previously contemplated.
“The PFS metallurgical work streams confirm strong gravity recovery, very low abrasion, and excellent overall gold extraction, with the weathered mineralisation demonstrating free-milling characteristics,” Pattison says.
The company says a coarser grind could lower power requirements and processing costs because the plant would spend less time reducing the ore to finer particles. It could also support higher throughput, although further test work and study outcomes are required.
The PFS will assess processing weathered material through carbon-in-pulp at a coarse grind before changing to carbon-in-leach at a finer grind for fresh material.
Testing classifies the weathered material as soft and fresh material as moderately hard. All samples returned a very low abrasion index, low lime and cyanide consumption, and no handling issues at slurry densities of up to 60% solids.
True specific gravity measurements ranged from 2.87–3.07 tonnes per cubic metre (t/m³), compared with bulk densities of 2.57–2.77t/m³ used in the current mineral resource estimate (MRE). Measurements are not directly interchangeable because true specific gravity excludes pores and voids.
The company says it is undertaking systematic density testing across each domain, with results to inform an updated MRE targeted for mid-December. The PFS remains scheduled for release in mid-November 2026.
PC Gold owns 100% of Spring Hill, where a July resource update increased the MRE by 84% to 43.6 million tonnes @ 1.1 grams per tonne gold for 1.51 million ounces. The project lies within granted mining leases and has environmental approvals for open pit mining and underground refurbishment.
Write to France Pinzon at Mining.com.au
Images: PC Gold
