The redeveloped Telfer operation was officially opened in July 2005. Telfer is located in the Great Sandy Desert in the Paterson Province of Western Australia, approximately 450 kilometres east-south-east of Port Hedland. Telfer is approximately 1,300 kilometres by air and 1,900 kilometres by road from Perth.
The operation is comprised of two mines, Telfer Open Pit and Telfer Underground. Telfer Open Pit contains 2 open pits, Main Dome and West Dome. Open pit mining currently takes place in the Main Dome. The underground mine is located beneath the Main Dome open pit.
Background and Redevelopment
Telfer was the founding project for Newmont Australia Limited after its discovery in 1971 and became the cornerstone of Newcrest following its creation in 1990. The original gold mine operated from 1977 to 2000 and produced almost 6 million ounces of gold. In October 2000, mining operations were suspended due to escalating costs, caused primarily by the prevalence of cyanide soluble copper encountered in the ore at the base of the Main Dome open pit. The mine site was placed on care and maintenance while redevelopment investigations and studies were undertaken.
A comprehensive feasibility study was completed in November 2002. This established an optimum strategy for mining and processing open pit and underground ore at Telfer. Instead of viewing copper as an impediment in the extraction process, the project sought to optimize the economic value of the deposit by producing copper as a by-product.
The Telfer project was implemented in two phases:
Stage 1 – establishment of the open pit mine, development of the ore haulage shaft for the underground mine, construction of the processing plant and site infrastructure including the gas-fired power station; and
Stage 2 – completion of the underground mine and associated infrastructure and construction of the pyrite concentrate treatment plant.
The two processing trains were commissioned on open pit ore in November 2004 and February 2005 respectively. Underground ore production commenced in March 2006 and the nameplate production rate of 4Mtpa was achieved in February 2007. Underground through-put has since increased to an annualized rate above 6 mtpa.
Gold and copper mineralization at Telfer is hosted within reef and stockwork domains in Proterozoic sediments. Mineralization has been defined in Main Dome to a depth of 1.3 kilometres below surface and in West Dome to a depth of 1.5 kilometres below surface. Both deposits remain open at depth and are subject to ongoing exploration. The Telfer sequence is generally oxidized to a depth of up to 200 metres below surface with local weathering along permeable structures up to 1,000 metres below surface.
The open pit mine is a conventional truck and hydraulic excavator operation. The existing Main Dome and West Dome pits will be deepened with cut-backs with an ultimate pit depth of 650 metres. Selective mining techniques are used for excavation of the high-grade reefs, while stockwork ore and waste are mined using bulk methods. The limited amounts of near-surface oxidized stockwork are also bulk mined.
The initial phase of underground mining uses the sub-level caving mining method as higher grades occur at the top of the ore body. The development of the mine is based on similar procedures and techniques which proved successful at the Ridgeway operation (Refer Ridgeway Operation). The main difference at Telfer is that crushed underground ore is hoisted to the surface via a 1,100 metre deep haulage shaft.
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