The White Foil gold deposit is a quartz stockwork hosted in a gabbro. The gabbro is differentiated broadly into a quartz-rich phase in the west. This quartz gabbro unit is the most hydrothermally altered unit and contains the bulk of the gold mineralisation. The White Foil deposit is bounded to the west by hangingwall volcaniclastic rocks. To the east mineralisation becomes irregular and uneconomic in the more melanocratic phase of gabbro. Mineralisation is controlled by sheeted systems of stockwork veining, which has imparted strong alteration and sulphidation to the quartz gabbro.

Structurally controlled deposit within a NNW trending shear associated with the regional Zuleika Shear Zone, on the lithological contact between the Victorious Basalt and Black Flag Volcanic Sediments. Mineralisation occurs in laminated quartz veins, brecciation and alteration zones with widths ranging from 0.2-20m along strike length of 0.3-1.0km.

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.

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.

White Foil is the open pit mine at the Mungari operations and utilises conventional drill and blast, load and haul methods.

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.

Grinding
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.

Process method: Three stage crushing, ball mill, 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.
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