Northparkes Copper-Gold Mine, Australia

Northparkes is an operational copper-gold mine located in the central west of New South Wales, Australia.

The mine received development consent in 1992, and operations commenced in 1993.

The operations include an underground block cave mine, a sub-level cave and an onsite processing plant. The copper-gold-silver concentrate produced from the operations is transported to the Port of Newcastle for export to international clients.

In December 2023, Evolution Mining acquired 80% interest in the Northparkes Mine from CMOC Group for up to $475m. The remaining 20% interest in the project is owned by Sumitomo Metal Mining and Sumitomo Corporation.

The life of mine is estimated to be 30 years with a considerable upside. The current Environmental Assessment allows operations until 2032.

Northparkes Mine Location Details

Northparkes Mine is located 27km north-west of Parkes in New South Wales, at 280m above sea level on the plains to the west of the Great Dividing Range.

The copper-gold project comprises the mining licences ML1247, ML1367, ML1641 and ML1743, which are enclosed by the exploration licences EL5323, EL5800, EL5801 and EL8377.

Overall, Northparkes owns more than 10,000 hectares of land, of which 1,630 hectare area is used for mining operations. The remaining area is used for commercial agriculture and to support logistical operations.

Northparkes Copper-Gold Mine Operational History

Northparkes mine, which hosts multiple large-scale porphyry copper and gold deposits, was discovered in 1976. Since the commencement of operations, the copper-gold mine leveraged highly mechanised, bulk tonnage caving methods to mine the underground.

The project was operated by Rio Tinto from 2000 to 2013. CMOC acquired Rio Tinto’s stake in Northparkes mine in December 2013, with the remaining 20% stake held by Sumitomo.

Northparkes was the first mine in Australia to utilise the block cave mining method.

The project delivered its 400th shipment in June 2020. The project has produced 1.168 million tonnes of copper and 1.464 million ounces of gold over 25 years.

Geology and Mineralisation

The Northparkes mine deposits occur within the Ordovician Goonumbla Volcanics and Wombin Volcanics.

The current life-of-mine development plan is focused on five porphyries, known as E26, E48, E22, E31 and GRP314. Apart from these, there are numerous other mineralised porphyries across the district.

The porphyries form narrow pipes, typically less than 50m in diameter that are vertically extensive. Mineralisation at the site extends from the porphyries into their host lithology.

Sulphide mineralisation is found in quartz stockwork veins, as disseminations and fracture coatings. The highest grades of mineralisation are generally associated with the most intense stockwork veining.

Northparkes Reserves

As of December 2022, reported Mineral Resources (excluding Ore Reserves) for Northparkes were estimated at 526.9 million tonnes (Mt) grading 0.55% copper, 0.19g/t gold and 1.87g/t silver.

The ore reserves at the property were estimated to be 101.4Mt at 0.53% copper, 0.27g/t gold and 1.87g/t silver.

Mining Operations

Most of the operations at Northparkes involve block cave mining, with open pit and surface stockpile reclamation making up minor contributions.

The project began open-cut mining at E22 and E27 ore bodies in 1993.

Underground block cave mining commenced at the property following the construction of the E26 underground block cave mine.

The second block cave mine E26 Lift 2 was commissioned in 2004. In 2008, an extension to the second block cave mine was commissioned.

The project’s E48 block cave achieved 100% mining automation in 2015.

Northparkes has also planned two new open pits for 2023 to extract ore closer to the surface. The new ore bodies are estimated to deliver 5.8 Mt of ore with a gold grade of 0.78g/t and 0.38% copper.

The mining process typically involves the recovery of broken rock from the draw points by 14t capacity electric and diesel-powered LHDs (load, haul, dump) loaders, which send the ore to a primary crushing station, consisting of a plate feeder and jaw gyratory crusher.

Ore Processing

The onsite processing plant located at the Northparkes site produces a copper-gold-silver concentrate.

Northparkes operates a conventional flow sheet for ore processing comprising crushing, grinding, flotation, thickening and finally filtration.

The plant is capable of process both copper gold oxide and sulphide ore.

Since 2017, the processing plant has been operating at a capacity of 6.4 million tonnes per annum (Mtpa). This has now been expanded to 7.6Mtpa.

The grinding circuit consists of two separate modules with a Semi-Autogenous Grinding (SAG) mill, oversize crushing technology, and two stages of ball milling and froth floatation.

The floatation process floats a sulphide concentrate to recover copper and gold-bearing minerals.

After floatation, the concentrate is processed through the concentrate thickener and then to the storage shed. The tailings are pumped from the floatation stage to a tails thickener and then out to the tailings storage facility (TSF).

The concentrate produced from the flotation circuit is thickened and filtered to produce a final concentrate. The final concentrate is trucked and railed to the Port of Newcastle, from where it is shipped to customers in Australia, Japan, China, and India.

Offtake Agreements

CMOC entered into a streaming agreement with Triple Flag Precious Metals (TFPM) in July 2020. Under the terms of that agreement, TFPM is entitled to gold and silver production from CMOC’s attributable share of payable production from Northparkes.

CMOC subsidiary IXM entered into an offtake agreement with Evolution to purchase copper concentrates produced from the Northparkes mine equal to Evolution’s 80% attributable interest over the life of the mine’s existing Ore Reserves.

Contractors Involved

Specialist equipment manufacturer Zitrón was engaged to provide engineering, design, construction, delivery, and installation of the switch rooms, MCCs, VSDs, transformers, instrumentation, and controls, for two primary fans.

Ampcontrol conducted significant electrical design and engineering works to support the Northparkes Expansion Project.