Highlights

  • OzAurum Resources (ASX:OZM) has achieved 95% gold recovery from Column 3 heap leach testwork at Mulgabbie North, approximately 130km northeast of Kalgoorlie.
  • The test used paleochannel material from diamond hole MNODH 022, crushed to minus 12mm, with a head grade of 2.58g/t gold.
  • Cyanide consumption of 0.26kg/t compares favourably with a typical 0.5kg/t benchmark.
  • The Mulgabbie North JORC (2012) mineral resource stands at 11.6 million tonnes at 0.70g/t gold for 260,000 ounces.

Strong Recovery Validates Heap Leach Approach

OzAurum Resources has reported a 95% gold recovery from heap leach column testwork on paleochannel material at its Mulgabbie North project in Western Australia. Column 3, using sample from diamond hole MNODH 022 between 21 and 29 metres depth with a head grade of 2.58 grams per tonne gold crushed to minus 12 millimetres, exceeded 60% recovery within 15 days, passed 80% by 35 days and reached the final 95% result. Cyanide consumption of 0.26 kilograms per tonne compares with a typical benchmark of approximately 0.5kg/t.

Why Heap Leaching Matters at Mulgabbie North

The Mulgabbie North resource averages 0.70g/t gold across 11.6 million tonnes for 260,000 ounces. At this grade, a conventional carbon-in-leach plant would face high unit processing costs. Heap leaching, which involves stacking crushed ore on lined pads and applying dilute cyanide solution, carries lower capital and operating costs and is suited to deposits where gold dissolves readily from coarser particles. The CEO Andrew Pumphrey confirmed that column testwork now covers all geological domains intended for heap leach processing.

Existing Resource Breakdown

The JORC (2012) resource comprises 1.475 million tonnes at 0.82g/t for 39,000 ounces Measured, 5.62 million tonnes at 0.71g/t for 128,000 ounces Indicated and 4.543 million tonnes at 0.64g/t for 93,000 ounces Inferred. The resource uses a 0.30g/t cut-off and is limited to 150 metres depth. The same diamond hole used for Column 3 also returned 6 metres at 11.64g/t gold from 22 metres, including 1 metre at 61.10g/t.

Fresh Rock Remains the Next Challenge

The current results apply to near-surface material. Fresh rock accounts for approximately 184,000 ounces, or 71% of the total resource, and the company regards it as the main growth lever beyond an initial stage. Heap leach testing of fresh rock is the critical next step to determine whether that material can be brought into later development stages.

Limitations

Laboratory column results do not always translate to full-scale heap performance. The headline 95% result is from a single column on a sample grading well above the resource average. No scoping study, mining study or ore reserve has been released, and no development decision has been made.