Carrapateena is a high-grade copper-gold project located approximately 160km from Port Augusta, Australia. OZ Minerals is developing the project, which is regarded as the biggest undeveloped mining project in Australia.
The A$916m ($650m) mining project is being constructed in two phases, with the first phase works commenced in September 2017.
Pre-feasibility study of the project was completed in August 2014, followed by the feasibility study in August 2017. The project received mining lease from the South Australian and Commonwealth Governments in April 2018 and is expected to be commissioned in the fourth quarter of 2019.
Carrapateena copper-gold project is estimated to produce 65,000 tons (t) of copper and 67,000 ounces (oz) of gold a year on an average, for a period of 20 years.
Carrapateena mine project location, geology, and mineralization
OZ Minerals acquired the project, which was discovered in 2005, for $250m plus contingent payments in 2011.
Carrapateena falls within the Olympic Dam copper-gold belt on the east of the Gawler Craton, which hosts prominent mines such as Prominent Hill, Olympic Dam, and the Moonta-Wallaroo historic mining district. The Craton hosts variably deformed and metamorphosed sedimentary, volcanic, and plutonic rocks from late Archean to Mesoproterozoic period.
The cylindrical-shaped deposit is contained within the brecciated granite complex, which hosts bornite and chalcopyrite copper mineralization.
Majority of the mineralization at Carrapateena is identified beneath 500m rock cover. The Carrapateena breccia complex is made up of sulphides such as chalcopyrite, pyrite, and bornite.
The hematite-altered breccias host gold mineralization in the form of very small size gold grains and a combination of gold and minor silver (electrum).
Ore reserves at Carrapateena Copper-Gold Project
Ore reserves at the Carrapateena copper-gold project are estimated to be 79Mt, containing 1.4 million tons (Mt) of copper, 1.8 million ounces (Moz) of gold, and 22Moz of silver.
Mining and ore processing at Carrapateena
Sub Level Cave (SLC) mining method will be applied at the underground Carrapateena mine. Long hole uphole blasting will be undertaken above the first SLC production level, while drilling and blasting will be undertaken above the SLC footprint to fracture rock mass.
Ore will be passed through three stages of underground crushing before transferring to the surface, via the decline, for further processing.
The underground mine will comprise two declines – the Tjati decline for personnel and equipment and another decline for primary ventilation and ore transportation to the surface.
The ore will be processed at the 4Mtpa copper concentration processing plant, which is being expanded to 4.25Mtpa. The crushed ore will be grinded and sent to the rougher / regrind circuit, followed by three stages of cleaner flotation.
The flotation concentrate will be upgraded and uranium removed by using a Jameson cell and three stages of mechanical cleaners. The concentrate will be thickened, filtered, and stockpiled before being stored in containers for load-out.
Infrastructure facilities at Carrapateena
Access to the project site is through a 52.5km unsealed road from Stuart Highway. Power will be sourced from a 132kV transmission line, from the existing South Australian electricity network at Mount Gunson. OZ Minerals also signed a transmission connection agreement (TCA) with ElectraNet for the supply of 55MW of electricity, for 20 years.
Operational water will be collected from the Radial Wellfield and Northern Wellfield, with water drilling exploration simultaneously ongoing in the Northern Wellfield.
The infrastructure facilities will also include an airstrip for transporting workers to site.
Workers will be accommodated at the 550-person Tjungu accommodation village.
Ausenco and Downer joint venture (JV) was awarded the engineering, construction and installation contract, worth A$312m ($238m), for providing the processing plant and other non-processing infrastructure for the Carrapateena copper-gold project.
PYBAR was awarded a two-year underground mining services contract, worth A$65m ($49.3m), in July 2016. The contractual scope includes construction of a 600m box cut, a 7,500m decline, and 1,500m of surface ventilation raises, in addition to supplying the surface infrastructure to support the project.
OZ Minerals has further engaged Downer EDI, in April, 2018, for providing underground mining services at the project under an A$660m ($513m) contract.
GR Engineering was awarded the engineering, procurement and construction (EPC) contract, worth A$16.3m ($11.77m), for the construction of Northern Wellfield.
KBR was engaged to provide project management services at Carrapateena, in October 2017.
NRW is responsible for the design and construction of a 1.6km sealed airstrip, 55km of heavy haulage access roads, and a tailings storage facility. The company also secured a sub-contract from Ausenco-Downer JV for conducting earthworks related to the Carrapateena processing plant and non-processing infrastructure.
Indigenous Contractors and McMahon Services were engaged to construct the exploration accommodation camp for the project, under an A$2.9m ($2.98m) contract.
Cobham Aviation Services was engaged to provide fly-in, fly-out (FIFO) services from the project to Adelaide and Port Augusta, for a period of three years.
Ventia is the supplier of high-voltage (HV) electrical infrastructure for the Carrapateena copper-gold project.