Aeris Resources’ Tritton Copper Operations, located near Nyngan in New South Wales, is targeting 24,500 tonnes of copper production in FY2019. Ore is currently sourced from the Tritton and Murrawombie underground mines. The operations are 100 per cent owned and operated by Aeris’ subsidiary, Tritton Resources Pty Limited.
History of the Tritton 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 tonnes 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.
Tritton Copper Opperations Mill
All Copper concentrate is sold to Glencore, following a life of mine offtake agreement executed in September 2012.
Mining and processing
At current production rates, the Tritton Copper Operations have an estimated mine life of five years. This said, Aeris has an extensive portfolio of identified exploration and development projects, and remains confident about the long-term growth prospects at the Tritton Copper Operation, and the potential for further discoveries in this highly prospective region.
Aeris continues to invest in strategic capital projects to underpin the future of Aeris’ Tritton Copper Operations. Recent capital projects include:
- Successful commissioning of the 864 metre, 5 metre diameterTritton Underground Mine ventilation shaft 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;
- The Murrawombie Underground Mine commissioned in FY2017, ramped up to full production levels in 2018; and
- The geophysical survey portion of the two-year, $7.5 million greenfields exploration program which commenced in the first half of FY2017 was completed. This program identified a further 65 kilometres of geological trend strike, multiple new anomalies for further exploration .
Tritton Underground Mine
Mining methods at the Tritton underground operations include sublevel open stoping or retreating bench stoping. Stope orientation is transverse and longitudinal depending on the geometry of the ore lenses. Backfill at the Tritton mine is cemented paste fill from reused mill tailings.
Ore from Murrawombie is trucked 30 kilometres by road train to the Company’s 1.8 million tonne per annum processing plant, located near the larger Tritton. Here the ore is processed through conventional crushing and flotation methods, producing a clean copper concentrate.
Concentrate is transported by rail to the port of Newcastle, and is then shipped to smelters, predominantly in the Asia Pacific region.
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 30 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.
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 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, 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. Ore will be 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