Simberi Island (Papua New Guinea)
|Area||40 km2 (15 sq mi)|
|Highest elevation||340 m (1,120 ft)|
|Province||New Ireland Province|
Geography and geology
Simberi is the northernmost and smallest of the three islands in the Tabar Group. The island is about 9 km long and 7 km wide and has an area of about 40 square kilometers. Its highest point in the highlands on the eastern side of the island is a 340 m eroded volcanic cone. The interior of the island is largely covered by rainforest. Most of the island's coast is steep and surrounded by a fringing reef together with a series of small islets. There is a barrier reef about 10 km offshore from the west coast. A 2 km strait separates Simberi from Tatau Island to the south west.
Simberi island is a potassium rich (high-K) calc-alkaline island arc volcano, the oldest in the Pliocene to Holocene Tabar-Lihir-Tanga-Feni (TLTF) volcanic arc that formed above a subduction zone.
The population is about 1100 and made up of nine clans who live in small coastal villages mainly in the north and west. The local language is a Simberi dialect of Mandara (also known as Tabar), ISO 639-3 language code "tbf", an Austronesian language spoken on the Tabar Islands.
Simberi Oxide Gold Project
St Barbara Limited, an Australian-based company, operate an open pit gold (and silver) mine called the Simberi Oxide Gold Project in the volcanic highlands on the eastern side of the island. The mine is wholly owned and operated by St Barbara Limited, who acquired the assets of Allied Gold, the previous operators of the Simberi mine, on 31 August 2012. Gold production started in February 2008. Mining was suspended in December 2009 after Allied Gold received a cease work order from the Mineral Resources Authority of Papua New Guinea because of local landholder issues. Mining has since recommenced.
Seven gold deposits have been defined in mining lease 136 (ML 136), which covers the central and eastern portion of Simberi Island, and other prospects have been identified. The gold deposits occur mainly on ridge tops and are all within 2 to 3 km of each other. Sorowar in the north is the largest resource while Samat North, South and East to the south are relatively small but relatively high grade. Pigiput, Pigibo and Botlu South lie between the Sorowar and Samat areas and are of intermediate tonnage but at a grade similar to Sorowar. The western area of Simberi Island within exploration license EL 609 is largely unexplored. Reconnaissance exploration for both oxide and sulphide mineralisation is planned.
As of June 2009, Allied reported that the total resources were 4.7 million ounces (Moz) gold, being oxide gold resources of 1.4 Moz and sulphide gold resources of 3.3 Moz together with 10.2 Moz silver.
Ore is delivered to the processing facilities on the eastern coast near Pigiput Bay by a 2,665 m long RopeCon aerial conveyor that can deliver 600 tonnes of ore per hour. The process plant is a conventional carbon-in-leach (CIL) gold process plant capable of treating 2.2 million tonnes of ore per year. In September 2010, Allied announced that it planned to increase its gold production to 100,000 oz per year. The oxide processing circuit at the Simberi operation will be expanded to 3.5-million tonnes a year, by June 2013.
Mine tailings are disposed of in the form of a slurry that has been pre-diluted with seawater using a deep sea tailings pipeline. The pipeline is 528 m long with the discharge point at a depth of 130 m. The tailings flow down a steep submarine slope and are deposited at a depth of more than 3 kilometers.
Production for the period from 1 July 2009 to 30 June 2010 was 64,327 oz.
In June 2009, Allied reported that the remaining mine life was estimated to be over 10 years. St Barbara Limited (Australia) acquired Allied in September 2012 and is the current owner of this mining operation. They are the largest employer on the island.
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