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Operations
Telfer
| Ownership |
100% Newcrest |
| Location |
North-west Western Australia |
| Year commenced operations |
Open pit – June 2003
Processing Plant – November 2004
Underground – March 2006
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| General Manager Operations |
Jason Grace |
| Style of mineralization |
Reef and stockwork domains in Proterozoic sediments, weakly metamorphosed, structurally deformed by folding and faulting and intruded by granites |
| Contained metals |
Gold-copper |
Resources*
- Main Dome Open Pit
- West Dome Open Pit
- Underground
- Vertical Stockwork Corridor
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369 Mt @ 0.88 g/t Au, 0.10 % Cu for 10.4 Moz Au and 370kt Cu
247 Mt @ 0.65 g/t Au, 0.06% Cu for 5.2 Moz Au and 140 kt Cu
62 Mt @ 1.4 g/t Au, 0.29% Cu for 2.7 Moz Au and 180 kt Cu
22 Mt @ 1.2 g/t Au, 0.50% Cu for 0.9 Moz Au and 110 kt Cu
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Reserves*
- Main Dome Open Pit
- West Dome Open Pit
- Underground
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282 Mt @ 0.91 g/t Au, 0.10% Cu for 8.2 Moz Au and 290kt Cu
152Mt @ 0.65g/t Au, 0.06% Cu for 3.1 Moz Au and 100 kt Cu
37Mt @ 1.5g/t Au, 0.33% Cu for 1.9 Moz Au and 120 kt Cu
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| Mining method |
Open pit and Underground |
| Processing method |
Twin train crushing, grinding, flotation, gravity, recovery and leaching |
| Nominal treatment rate |
17-21 Mtpa based on ore hardness |
| Product |
Gold-copper concentrate, bullion |
| Forecast mine life |
Underground 2017
Open pit 2023
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* Per 30 June 2010 Mineral Resource and Ore Reserve statement.
Overview
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.
Geology
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.
Mining
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.
Processing
The Telfer concentrator comprises a dual train comminution circuit followed by flotation and a carbon-in-leach (CIL) circuit. The process flowsheet is more complex than the other operations because of the need to process a range of mineralization and ore types.
The two processing trains contain two stage grinding circuits each comprising a 15MW SAG mill and 13MW ball mill. Both streams contain a gravity gold recovery circuit. Approximately 40% of the gold at Telfer is produced as doré which is smelted on site. Following the gravity recovery circuit ore with:
- a relatively low pyrite content is treated in a conventional single stage flotation circuit to produce gold-copper concentrate; or
- a higher pyrite content is treated via a sequential flotation process. The first stage is a conventional copper flotation with depression of pyrite to produce a gold-copper concentrate. Tails from the first stage are refloated to produce a pyrite-gold concentrate which is leached with cyanide in a conventional carbon-in-leach circuit to recover the remaining gold as doré.
The gold-copper concentrate is trucked to Port Hedland for shipping to smelters, primarily in the East Asia region.
Oxide ores are treated on dump leach pads to produce doré.
Services and Utilities
Power is generated on site using three gas turbines with a total installed capacity of 138MW. The turbines operate on natural gas which is transported from the Western Australian coast to Telfer via a 450 kilometres purpose built pipeline owned and operated by Australian Pipelines Group.
The pre-existing diesel power station provides back-up power and additional capacity during periods of peak load.
Telfer is a fly-in, fly-out operation with about 1,000 personnel onsite. The site has an all-weather air strip capable of handling medium-sized commercial aircraft.
Future Developments
Studies are being undertaken to enhance Telfer’s production and cost profile. These include the following:
- assessing alternative underground mining methods to reduce cost and increase productivity in the deeper, lower grade parts of the ore body. These alternatives include trough caving, a variant of block caving;
- Analyzing the economic viability of a lower cost open pit materials handling system of in-pit crushing and conveying; and
Exploration is focused on targets identified in and around the Telfer Deeps sublevel cave operation and regional exploration around the Telfer ore body.
Key production and cost data for Telfer is illustrated in the graphs below. As open pit and underground ores are combined in the treatment plant, costs for the site are quoted on a combined basis.
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