Simberi is the northern most island in the Tabar group of islands in the province of New Ireland - the eastern most province of Papua New Guinea (PNG) some 900 kilometres from the capital of PNG, Port Moresby. Most of the island's coast is steep (up to 300 metres in elevation) and surrounded by a fringing reef and deep plunging seawalls given the island’s volcanic origins. Rainfall is high throughout the year with a not so distinct wetter period from October through to April. Mean annual rainfall is 3 meters with monthly totals varying from 30mm to 600mm.
It is home to about 900 islander locals, who speak a common language, Mandara, and share the same cultural ties and beliefs across the island chain. Many speak English and Pidgin. The Tabar island clans are traditionally matrilineal.
Access to Simberi is via a three hour charter flight from Port Moresby. Charter flights also stop at Kavieng (the capital of New Ireland province) and at Rabaul (in New Britain province). The 1400 metre airstrip is adjacent to the Piking Plantation some 3km from the process plant whilst a cargo vessel, the “Lady Geraldine”, provides supplies to Simberi at the 20metre long concrete wharf at Pigiput Bay. Fly-in fly-out staff and contractors stay at the 250-bed Pigiput camp.
There is evidence of very limited alluvial gold workings, probably dating from the 1920s, near the Matanabol Creek on Simberi. In 1982 Kennecott (later acquired by Rio Tinto), Nord Resources and Niugini Mining formed the Tabar JV to explore for gold on Simberi. In 1993 Nord acquired all the interests and undertook exploration and in 1996 commissioned a feasibility study which led to the grant of a Mining Lease (ML 126) in December 1996. As gold prices fell in 1997 the project was put on hold.
Allied Gold became involved in 2004 and reinstituted a feasibility study and by 2006 mine and mill construction commenced. In November 2007 mining operations began at the Samat East deposit and the first ore was processed in February 2008. Allied was acquired by St Barbara in September 2012.
Current mining activities are restricted to the eastern half of the island covered by a 2,560 hectare Mining Lease (ML136). Ore at Simberi is sourced from seven currently defined open pits: Sorowar, Samat North, Samat South, Samat East, Pigput, Pigibo, and Botlu South. The Sorowar Pit is currently the largest defined oxide pit. The stripping ratio for the first few years was less than 1:1 with ‘free dig’ bulk mining using traditional truck and shovel. Current mining plans of the oxide cap suggest a strip ratio of 1:1 for the foreseeable future. Ore from the pit is delivered to the ROM pad (Sorowar feeder) where it is crushed and conveyed down an innovative and energy-efficient 2.7 km rope conveyor that transports the ore to a stockpile in front of the process plant.
Processing involves a traditional Carbon in Leach (CIL) process with five CIL tanks. The plant underwent a ‘debottlenecking’ program in 2010 to lift mill throughput to 2.4 Mtpa. During late 2013 the plant capacity was expanded to 3.5 Mtpa with installation of a SAG mill to lift gold output over time towards a run rate of 100,000 ozpa.
Power is generated on-site. This is scheduled to transition from diesel to heavy fuel oil during 2014.
Below the oxide pits on Simberi is a significant sulphide ore resource. In November 2010 a prefeasibility outlined the options for a 1.5 Mtpa sulphide circuit. A future study is planned to examine potential expansion of the plant to allow processing of sulphide material.