Didipio

Overview

The Didipio Project is located approximately 270 km NNE of Manila in the Nueva Vizcaya Province of Philippines.

Alluvial gold was discovered in the Didipio area in the 1970s. Oceana Gold Ltd operates and manages the Didipio project through its wholly owned subsidiary OGPI.

The Didipio deposit will be mined by both open pit and underground methods. Open pit production is scheduled to start at the end of 2012. The underground mining operation is scheduled to commence production in 2022. Open pit and underground mines will run concurrently in the last 7 years of operations. Didipio is anticipated to produce an average annual production of approximately 100,000 ounces of gold and 14,000 tonnes of copper in concentrate for an anticipated 16 year mine life. Concentrate would be trucked for over 320 kilometers to one of the existent ports.

Location

The Didipio Project is located approximately 270km NNE of Manila and 35km to the ESE of the provincial capital of Bayombong within the Province of Nueva Vizcaya in Philippines. Philippines is an island state located in Southeast Asia in between Vietnam and Indonesia.

The project area is located within the southern part of the Cagayan Valley basin in north-eastern Luzon.

The area is bounded on the east by the Sierra Madre Range, on the west by the Luzon Central Cordillera range and on the south by the Caraballo Mountains.

Climate is tropical with most of the precipitation received during the monsoon seasons i.e. June to September, and October through January.

Vegetation consists of grassland, brush land and low-density forest.

Geology & Mineralization

Alluvial gold was discovered in the Didipio area in the 1970s. Alluvial gold and the clay-altered zones were sluiced by artisanal miners. They also excavated small undergound mining works on high-grade quartz-sulphide zones.

The Didipio Project is an alkalic gold-copper porphyry system,  elliptical in shape at surface (450m long by 150m wide) and with a vertical pipe-like geometry that extends to at least 800m to 1000m below the surface. The mineral deposit is hosted by a series of hydrothermally altered and structurally controlled Miocene intrusives, which were emplaced along a regional fault structure.

Mineralization is predominantly hosted by a monzonite stock. Chalcopyrite and gold (electrum), along with pyrite and magnetite, are the main metallic minerals in the deposit. Chalcopyrite occurs as fine-grained disseminations, aggregates, fracture fillings and stockwork veins. Pyrite is the other main sulphide mineral, occurring principally as disseminations and fracture fillings.

The deposit is oxidized from the surface to a depth of 15m to 60m. Secondary copper minerals like malachite and chrysocolla are present in this zone that blankets the mineral deposit.

Mining & Operations

The Didipio deposit will be mined by both open pit and underground methods. Open pit production is scheduled to start at the end of 2012. The underground mining operation is scheduled to commence production in 2022. Open pit and underground mines will run concurrently in the last 7 years of operations.

For open pit mining a reverse circulation drill rig would be employed in sampling and definition ahead of mining. Ore is to be trucked to the ROM pad or the low-grade stockpile. Waste rock which has a negligible potential for acid rock drainage would be used in the construction of the Tailings Storage Facility. Water table would be lowered by a system of advanced dewatering bores.

Underground mining operations would begin through the construction of a decline in parallel with open pit mining. The mining method of choice is sublevel open stoping with cemented tailings backfill. 

Process 

Didipio is processing ore by using a crushing, grinding, gravity recovery and flotation method.

The open pit operation has been scheduled to deliver to the mill ore of sufficient grade to achieve 200,000 gold equivalent (AuEq) ounces (oz) per year until the underground mine starts.  Low grade ore stockpiled during open pit operations will be milled at the end of both open pit and underground operations. Concentrate is to be trucked to an existing copper concentrate storage and shipment facility at Poro Point.

Water is to be sourced from dewatering boreholes. Potable water treatment plants would cover the needs of the camp and process plant.

Environment & Community

The company abides by the rules and regulations of the Labour Code as well as those set by Government Regulatory Agencies in the Philippines. Preference is given to local community members for employment opportunities at the project.