The Ok Tedi mining operations are centred on the Mt Fubilan deposit in the upper Fly River catchment in the remote Star Mountains, Western Province.

Mt Fubilan is a rich coppergold-silver deposit with several phases of mineralisation centred on two intrusions, known as the Fubilan monzonite porphyry, located in the northern half or Centre Pit area and the Sydney monzodiorite stockworks with subsequent alteration in the south. Majority of the ore is found in the sulphide skarns, located adjacent to the intrusions along the contacts with the limestone and siltstone units.

Mining of the Mt Fubilan Ore Reserves is carried out as a large open pit operation. In March 2016, a pit wall failure located in the West Wall interrupted access to lower levels in the pit. The collapsed material caused a blockage in the pit floor underdrainage system resulting in the lower levels of the pit becoming submerged.

Ore is mined and transported to a primary crusher as first stage processing or to a Run of Mine (ROM) stockpile, where blending of various ore types can take place. Waste rock is characterised according to its Acid Rock Drainage (ARD) potential and disposed of in the Taranaki, Harvey Creek, Paris, Moscow or Vancouver waste dumps. Limestone waste rock is selectively dumped together with potential ARD waste rock to neutralise any acid generation.

Mining is conducted using conventional drill and blast techniques, with shovel and excavator loading equipment. The company has completed an upgrade of its mining equipment, standardising on Caterpillar equipment including 33 trucks (793F), eight trucks (789C), four loading shovels (6050) and four excavators (6030) and ancillary equipment. A fifth shovel (6050) was commissioned in January 2017. The mine uses the Modular PTX Dispatch fleet management system to optimise movements.

The deposit is mined as a large open pit with a flotation processing plant capable of treating up to 24 million tonnes per annum (Mtpa), and currently recovering copper and gold into a saleable concentrate using conventional technology. The concentrate product contains approximately 25% copper with gold content in the range of 15 to 25 g/t. Copper concentrate is piped 156 kilometres (km) south to the Kiunga port facilities located on the Fly River. The concentrate is dried, stored, blended and then shipped by barge down the Fly River to Port Moresby where it is transferred to a silo and storage vessel before being exported overseas.

The ore is crushed in a primary crusher at a nominal 8,000 tonnes per hour (tph) and conveyed to a primary ore stockpile. The primary ore is then ground (two trains each comprising a SAG mill and two ball mills) to a final grain size of approximately 180 microns. This material is treated in a twin parallel standard mineral flotation circuit to produce a copper, gold and silver concentrate of approximately 25% copper and between 15 and 25 g/t gold. A portion of gold is also separately captured utilising a gravity gold circuit. The concentrate is thickened and piped as slurry to handling facilities at Kiunga where it is filtered, dried and prepared for shipping.