Mineralisation at Frog’s Leg is hosted within a number of steeply dipping NNW-SSE structures that are vertical or dipping steeply (~80 degrees) to the west. Surface and underground drilling intersect the mineralisation at an angle to minimise bias.

The Frog’s Leg deposit is located in the southern portion of the Kundana mining area, within the Achaean Norseman-Wiluna greenstone belt of the Eastern Goldfields Province. The Kundana gold deposits are structurally related to the Zuleika Shear Zone, a regional NNW-trending shear zone that juxtaposes the Ora Banda domain to the east and the Coolgardie domain to the west. The Frog’s Leg deposit is located on the sheared contact between the porphyritic “cat rock” (regionally known as the Victorious Basalt) and volcaniclastic rocks of Black Flag Beds.

The ore lodes are between 2m and 20m thick and occur as sub-parallel lodes.

At underground mine, Frog’s Leg mining methodology is top-down long hole stoping, with paste fill.

5m x 5.5m decline from portal in pit, then twin declines from 125 metres below surface (mbs) to access north (Mist) and south (Rocket) sections Deepest current level is 700mbs.

Three stage crushing: Primary Metso C140 Jaw crusher (220kW) -1250 x 940mm throat- feed size 800mm, product size p80-120mm. Secondary(1) and tertiary(1) crushers: Metso HP 4 (315kW) Product size 17mm. Product Screen: Joest inclined vibrating screen 2.44 x 7.6m. 4 x conveyor belts, Belt and static magnets as well as a rock breaker for the primary crusher.

Ball Mill with 4,500kW installed power, Mill size 5.5m(dia) x 8.74m(l), Polymet composite liners, Classification Weir Cavex 250mm (x11) Grind size p80 – 106 µm. Gravity & CIP

Recovery method - Gravity and CIP.

Leaching:
2 x 1,140 m3 tanks
Adsorption: 6 x 750 m3 tanks
Elution: split AARL
Electrowinning: 3 x Consep tanks [2 x carbon-in-leach (CIL), 2 x gravity]

Gravity circuit
Concentrator: 2 x Knelson
Intensive Leach: Consep Acacia

Processing plant operational data was used to drive higher gold production. Some of the initiatives the team executed to achieve this result included:
- Reviewing and analysing grinding circuit data which identified instances where capacity was not being taken advantage of and making changes which led to increases in mill utilisation
- Ensuring the availability of crushed ore stock in front of the mill so that crusher shutdowns have less impact.

The $A12.4 million improvement has been achieved due to higher gold production than previously obtained as a result of these process improvements through the analysis of data.