History of the Tritton Copper Operations
Mining within the Tritton area in modern times began in 1992 at the Murrawombie open pit and heap leach operation by the Girilambone Copper Company, a Joint Venture between Straits Resources (now Aeris) and Nord Pacific. The Girilambone Copper Company eventually became a wholly owned subsidiary of Straits Resources. Operations at the Girilambone copper project involved the mining of several open pits to recover copper oxide ore that was treated by heap leach, followed by solvent extraction and electrowinning processing to produce copper cathode. The Murrawombie pit was the largest of the mines. Open pit mining at Girilambone ended in 1999, although copper cathode production continued for two more years.
Leaching of residual copper from the Murrawombie heap leach continues today. Approximately 400 tonne per year of copper is extracted from the leach solution as a copper cement by reaction with scrap iron.
Exploration by the Straits Resources and Nord Joint Venture resulted in the discovery of the Tritton deposit in 1995 as part of an exploration program focused on the historical Budgerygar and Bonnie Dundee copper gold mines. Geophysical techniques were successful in identifying the buried Tritton deposit 800m to the south of these historical workings. Tritton Resources Limited was formed to develop the Tritton deposit. It was for a time listed as an independent company on the Australian stock exchange, before being privatised as a subsidiary of Straits Resources.
All Copper concentrate is sold to Glencore, following a life of mine offtake agreement executed in September 2012.
The Tritton deposit is a large, (over 20 million tonne), copper dominant VMS system, discovered in the mid 1990s via geophysical methods.
Mining of the Tritton ore body commenced in 2004 with the development of an access decline and construction of a sulphide ore processing plant. Copper is extracted via conventional crushing and flotation circuits producing a copper concentrate. Stope production commenced in March 2005. In its first year of production, Tritton produced 23,088 tonnes of copper in concentrate.
Tritton reached 10 years of production in 2015 with significant Mineral Resource remaining. As at 30th June 2017, the combined Measured, Indicated and Inferred Tritton Mineral Resource Estimate is 9.4 million tonne at 1.5% Cu for 140 thousand tonne of copper metal. Find out more
Brownfields exploration at the Tritton deposit has identified a number of opportunities to extend the life of this operation, including extensions to the orebody, which remains open at depth. An 864 metre, 5 metre diameter ventilation shaft was commissioned at the mine in September 2017. This essential infrastructure ensures that production at Tritton can be maintained at more than one million tonnes per year as mining moves deeper.
Murrawombie Underground Mine
The Murrawombie deposit is located in the southern area of the Girilambone Complex. The deposit is the largest concentration of copper metal outside the Tritton deposit, with 100 thousand tonne of contained copper (6.6 Million tonnes at 1.5% copper as at 30 June 2017).
Murrawombie was mined in the 1990s as an open pit to access the oxide portion of the deposit for heap leach processing. However the sulphide portion of the deposit was not mined at tht time due to its unsuitability for heap leaching.
The Murrawombie underground mine was commissioned in 2017 and ramped up to full production levels in 2018.
The production from Murrawombie mine has replaced the production from the Larsens and North East mines, concluded in July 2016, with planned production rates of up to 650,000 tonnes per year.
The mine design incorporates cemented backfill allowing selective mining methods in order to mine areas of higher copper grades. Ore is trucked to the Tritton plant for processing as a blend with Tritton mine.
Stope backfill will use the crushed rock on the Murrawombie heap leach pads, helping with closure of the pad. Find out more