Porgera Mine is an epithermal vein-type gold-silver deposit but it shares many characteristics with porphyry copper deposits. Remnant heat from the intrusive rocks drove the boiling and upward migration of hydrothermal fluids and resulted in the emplacement of mineralization. The movement of these fluids was controlled by permeability of the rock mass, which developed in and around faults and tectonic zones of dilatancy. As such, the mineralization tends to occur in tabular bodies and breccia zones, the geometry of which is strongly influenced by the orientation of fault structures and subsidiary fractures. Deposition of ore minerals in epithermal systems is also dependent upon temperature and hydrostatic pressure. These conditions are generally closely related to elevation, with reduction of both temperature and pressure as the fluids migrate upwards.

Conventional open pit (truck and excavators) and underground mining (long hole open stoping using paste backfill).

Open pit : Conventional truck/excavator operation
– Pit dimensions:
– 2.0km long x 1.2km wide x 400m deep
– Typical bench height: 10m

- Underground:
– Long hole open stoping
– Paste backfill

The major components on the Porgera processing plant include:

- crushing circuit and coarse and fine ore storage;
- grinding circuit;
- gravity and regrind circuit;
- flotation circuit;
- pressure oxidation and tailings neutralisation circuits;
- leaching and adsorption circuits;
- acid wash and stripping elution circuit;
- electrowinning and gold refinery;
- oxygen plant;
- chemical storage and mixing;
- cyanide destruct plant; and
- tailings pipework and infrastructure.