McPhillamys gold project is a high-grade gold mine being developed in Blayney-Kings Plain district of New South Wales, Australia.
The project was previously owned by LFB Resources, a joint venture between Newmont Exploration and Alkane Resources. LFB was acquired by Regis Resources in November 2012 transferring the ownership of the gold mine to the latter.
Preliminary environmental assessment (PEA) of the project was submitted to the NSW Department of Planning and Environment (DPE) in July 2018. The definitive feasibility study (DFS) is anticipated to be completed by December 2018.
Regis proposes to start construction and mine development immediately following the receipt of approvals, which are expected in the second half of 2019. Mining operations at the Australian gold mine are forecasted to start in 2020.
The McPhillamys gold project is expected to extract and process up to seven million tonnes of ore per annum (Mtpa) and produce an average of 192,000 ounces of gold per annum over a ten-year mine life. The project is expected to create approximately 200 construction jobs and 250 operational jobs.
McPhillamy gold project geology and mineralization
The McPhillamys gold project is located approximately 250km west of Sydney in the Central West region of New South Wales.
The deposit is located within dacite-rich volcaniclastic rocks of the Silurian-aged Anson formation of the East Lachlan Fold Belt of New South Wales. Gold mineralization is found within a north-south striking and east-dipping strongly foliated felsic to intermediate volcanic and intrusive rock unit.
The probable ore reserves of McPhillamys gold project are estimated to be 60.1Mt grading 1.05g/t of Au. The mine is estimated to contain 2.03 million ounces (Moz) of gold.
Mining and processing of ore at McPhillamys
Conventional open-cut methods of mining, involving drilling and blasting followed by loading and hauling, will be applied at McPhillamys.
The single open-pit will be mined in two stages to assist in reducing total earth-moving production requirements, most likely in the first two years of operation. The mine plan includes blasting 70% of the oxide domain and the entire transitional and fresh domains prior to load and haul of the material to the waste dumps, low-grade stockpile, or run-of-mine (ROM).
The conventional processing plant at the mine will be capable of processing 7Mtpa of ore at a nominal milling rate of 841tph. Ore will be crushed in a three-stage crushing unit at a design rate of 1,250tph to a P80 size of 15mm and then stored on the crushed ore stockpile.
The grinding circuit will further reduce the crushed material to a P80 of 150 microns and the ground ore will be forwarded to the gravity separation circuit, which will recover approximately 4% of the feed material comprising coarser gold particles and heavier sulphides.
An ultra-fine grinding circuit will then reduce the gravity concentrate size to 10 microns. Gold in the gravity tail will be leached using oxygen and cyanide and adsorbed onto activated carbon using conventional carbon-in-leach (CIL) technology.
Gold will be stripped from the activated carbon and forwarded to electro-winning circuit for producing doré bars, which will be smelted and stored in a secure gold room installed with electronic security surveillance systems.
The McPhillamys gold mine will be accessed through a site access road from the Mid-Western Highway near the western end of Walkom Road.
Power supply for the project will be sourced from the NSW electricity grid through a nearby substation and an existing 66kV power line.
Water for the project will be sourced from the Mt Piper power station and Springvale mine near Lithgow. Regis has executed a non-binding heads of agreement with Centennial Coal Company and Energy Australia for providing between four and five gallons of water a year (GLpa) for a period of ten years.
The project also has access to approximately 4.5GLpa of water supply from the Lachlan catchment under long-term leases.
Cube prepared the pit optimizations and practical pit design of McPhillamys gold project as part of the pre-feasibility studies, while Mintrex calculated the capital costs associated with the processing plant.
SRK Consulting was engaged for identifying structural and geological controls on the gold mineralization at mine, while EMM Consulting was engaged for hydro-geological modelling.
RW Corkery & Co assisted Regis in preparing the environmental impact statement for the project, while ECG Engineering prepared the engineering design of the power supply.