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.

The priority of the Geology and Exploration team for 2019 was quantifying near-mine resources within the SML, particularly in the Sulphide Creek area at the New York, Darien, Hagley Park and Wellington prospects. Exploration activities outside of the SML included drilling at Mt Anju, Dorongo and Mt Kwang, where previous exploration had identified intrusive rocks hosting copper and gold mineralisation. Statutory work and expenditure commitments were maintained on all exploration licences. The focus for 2020 will be to continue resource definition drilling within the SML. The aim is to convert exploration targets to Mineral Resource status so the resources can be included in the Life of Mine models. Exploration drilling will also be undertaken on identified targets on and adjacent to SML 1. Regional work will be done on the Mt Frew prospect (EL2156), EL2256 (Mt Anju) and EL2472 (Bubu). OTML reduced its tenement holding to 476 square kilometres (km2) during 2019 with area reductions on EL1677 and EL2289 in line with licence conditions.

Near Mine Exploration Targets
The exploration priority for 2019 was to increase the geological understanding of known mineralised material in SML 1. A total of 23,927 m was drilled in 2019 with 42 holes completed to target depth.

Hagley Park Skarn
Nine holes have been drilled into the Hagley Park skarn, presently sufficient to construct a detailed geological model and define the mineralised envelope.

New York Breccia
In 2019, ten additional holes were drilled into the New York Breccia and the knowledge obtained has contributed positively towards an understanding of the morphology. The New York Breccia appears to be a large pipe-like body approximately 600 m by 400 m in plan, extending with broader dimensions to a depth of at least 1,000 m from surface. The drill holes also intersected what is still interpreted as New York Breccia in excess of 200 m beyond the main pipe, but in localised areas parallel and above the Taranaki Thrust as sill-like bodies. This system still remains open vertically to the north and the south.

Mineralisation occurs as interstitial sulphides in the form of pyrrhotite, pyrite, sphalerite and chalcopyrite. Free gold is commonly observed in sulphide-rich zones. Gold mineralisation hosted within the New York Breccia pipe is interpreted to be intrusive-related and hydrothermal in style.

Infill drilling in the upper parts of the system is planned for 2020, together with deeper drilling to investigate possible copper mineralisation at depth. A concept study is under way to identify potential mining options and bulk samples have been collected from drill core for preliminary metallurgical test work.

Wellington
Mineralisation at Wellington consists of a series of magnetite skarn and calc-silicate endoskarns associated with the Taranaki Thrust and limestone intrusive contacts. A program of resource definition drilling was initiated in 2019 and this is expected to be completed in early 2020.

Darien
Darien is a small copper-gold porphyry system immediately westwards of the New York Breccia. Historic drilling indicated copper mineralisation, but the extent of the system has never been accurately delineated. Mineral Resource definition drilling commenced in late 2019 and will be completed in 2020.

Waterfall Epithermal System
This epithermal system is a broad area of alteration containing porphyry related veins at the site of the waterfall in Sulphide Creek. These veins appear to be directed towards a shallow intrusive body beneath the main area containing epithermal veins. Drilling is underway to test for potential gold mineralisation in this area.

Gilor Breccia
This breccia was discovered in Upper Gilor in 2017. The outcrops resemble both the New York Breccia and the Townsville breccia and is probably a hybrid of both types. Drill testing is planned for early 2020.

Gilor Skarn
Reconnaissance drilling in early 2019 intersected a broad zone of skarn mineralisation on the margins of the Komgubup Sill in Lower Gilor Creek. Encouraging results were obtained (79.5 m at 0.73 g/t Au from 203 m) and follow up drilling is planned in 2020. Aerial image showing pit location, SML boundary and location of key targets in SML 1.

Mining of the Mt Fubilan Ore Reserves continues to be carried out as a large open pit operation. Mining is conducted using conventional drill and blast techniques, with shovel and excavator loading equipment. Ore is mined and transported to a primary crusher as first stage processing or to a Run of Mine 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 one of five waste dumps. Limestone waste rock is selectively dumped together with potential ARD waste rock to neutralise acid production.

The current pit design and pit sequencing has been developed to maximise value while meeting environmental constraints agreed with mine-affected communities

With approximately 9,000 mm of rainfall per annum, incident rainfall and runoff contributes significant volumes of free water draining into the pit. Rainwater also permeates into the rock mass contributing to instability due to increased pore pressure.

Comprehensive monitoring of hydrological and geotechnical factors are incorporated in our mining strategy and plans to ensure safe operations.

OTML’s business operations are centred on the Mt Fubilan deposit located in the Star Mountains. The deposit is mined as a large open pit with a flotation processing plant capable of treating in the order of 22 to 24 million tonnes per annum (Mtpa), and currently recovering copper and gold into a saleable concentrate using conventional technology. The throughput rate is highly dependent on the ore lithology delivered from the mine. 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 customers using commercial shipping services.

The ore is crushed in a primary crusher at a nominal 8,000 tonnes per hour (tph) and conve ........