The Tritton Copper Operations located near the town of Nyngan in central New South Wales is operated by Tritton Resources Pty Ltd, a 100 per cent owned subsidiary of Aeris Resources Limited.

There are two active underground mines, Tritton Underground Mine (Tritton) and Murrawombie Underground Mine (Murrawombie). The combined ore production from both mines is treated at the Tritton ore processing plant, which has a processing capacity of up to 1.8 million tonnes per annum, depending on the hardness of the ore.

There are four additional mine projects scheduled for future production, which together with Tritton and Murrawombie form the current Life of Mine plan (LOM). These projects will supplement and then replace production from Tritton and Murrawombie as the latter are exhausted.

Brownfields exploration at the Tritton deposit has identified a number of opportunities to extend the life of the operation, including extensions to the orebody.  Importantly, both the Tritton and Murrawombie deposits remain open at depth.   Aeris is confident that drilling will grow these known deposits and that mine life will progressively extend. Exploration success in finding new deposits in this highly prospective region could increase production rates and/or increase the life of the operation. 

 

 

 

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

 

Processing

Ore from Tritton and Murrawombie  is transported to Aeris’ 1.8 million tonne per annum processing plant, located near the Tritton mine. 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.

 

Mining at 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.

Tritton Underground Mine

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 2018, the combined Measured, Indicated and Inferred Tritton Mineral Resource Estimate is 10.3 million tonne at 1.4% Cu for 150 thousand tonne of copper metal. Find out more

The Tritton Underground Mine successfully transitioned to a new mine design in response to a change in orebody geometry, with changes to stope extraction sequence on the lower levels to eliminate pillar stopes. 

Additional upgrades to the ventilation circuit  were completed in 2017 to sustain ore production at more than a million tonnes per annum.  This investment, together with changes to the mining sequence have set Tritton up for stable stope production in coming years as mining extends at depth.

Aeris is committed to continued investigation and investment into mining equipment and technology.  Some recent examples have included a significant upgrade of the tele-remote loader operation system allowing loading operations to be conducted from the surface control room, and bogging ore from the stopes to be continued during blast clearance and shift changes.

 

 

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 84 thousand tonne of contained copper 5.4 million tonnes at 1.5% copper (as at 30 June 2018).

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 development of Murrawombie commenced in 2016 and the mine reached full production rates during 2018.  Strategically, Murrawombie was developed to replace the now exhausted North East and Larsen underground mines.

Like Tritton, the Murrawombie deposit remains open at depth, presenting the opportunity for production to increase over time, and/or extending the life of the operation.

Ongoing grade control and geology mapping and modelling have provided a greater understanding of the Murrawombie orebody, which in turn has resulted in changes to mining methods to deliver improved and sustainable performance.   For example, sub-level caving has been abandoned in favour of more straightforward mining by sub level open stope design, allowing the extraction to be selective and enabling Aeris to target higher grade portions of the deposit.

Future changes in geology will be more modest and are not expected to require significant changes in mine design. Find out more