Capricorn Copper Mine, Queensland, Australia
The Capricorn copper mine (formerly Mt Gordon and Gunpowder mines) is one of largest copper mining projects being undertaken in Australia.
The Capricorn Copper joint venture between Lighthouse Minerals (LHM) and EMR Capital (EMR) acquired the mine in October 2015 from Aditya Birla, a company based in India.
The copper mine is currently undergoing a refurbishment and restart programme with a A$110m (approximately $81m) investment, and is expected to commence ore production in the final quarter of 2017. The mine is anticipated to produce 30ktpa of copper in concentrate over its initial mine life of ten years.
Details of the Capricorn refurbishment and restart programme
Capricorn Copper has initiated restart execution studies (RES) to identify the prospects of restarting operations at the Capricorn copper mine. A restart and refurbishment project (RRP) has been established to estimate the capital costs and undertake readiness programmes required to restart mine operations.
The study concluded that the desired operational efficiencies could be achieved through the maintenance of existing facilities, replacement of outdated technology, expansion of existing production system, and construction of new equipment / facilities.
Commissioning of new process equipment will reduce the project's risk profile. The concentrator refurbishment is expected to be completed in 2017, while the mine recommissioning is expected in the fourth quarter of 2017.
Geology and mineralisation of Capricorn copper mine
Located approximately 125km north-west of Mt. Isa in north-west Queensland, the copper mine is hosted within the Western Fold Belt of the Mount Isa Inlier. The Inlier comprises early to middle Proterozoic rocks and hosts three tectonic units, namely the Western fold belt, the Kalkadoon - Leichhardt belt, and the Eastern fold belt.
The Western fold belt is further categorised into the Lawn Hill Platform, Leichhardt River Fault Trough, Ewen Block, and the Myally Shelf zones, while the Eastern belt is categorised into the Mary Kathleen, Quamby-Malbon, and Cloncurry-Selwyn zones.
The Capricorn copper project occurs within the western part of the Leichhardt River Fault Trough and is connected with a regional scale transpressional dextral strike slip system called Mount Gordon Fault Zone (MGFZ).
The mine comprises five deposits, namely Mammoth, Mammoth North, Esperanza-Pluto, Esperanza South, and Greenstone.
Most of the copper mineralisation at Capricorn is hosted as a set of interconnected east to north-east trending faults and fault splays interconnected with the north-trending MGFZ. Mineralisation occurs in stockwork veins, breccias and as adjacent replacement of host rocks located within and close to the faults.
Capricorn copper mine reserves
The Capricorn copper mine is expected to contain proven and probable ore reserves of 8.47 million tonnes (Mt) containing 167,600t of copper metal grading 1.98% Cu.
Mining and processing of ore from Capricorn copper mine
The Capricorn copper mine has seven closely located primary ore bodies, and mining is to be conducted from multiple ore bodies through two declines.
Longitudinal sub-level caving (LSLC) method of mining will be applied at the Esperanza South deposit, while Long Hole Open Stoping (LHOS) with paste fill will be implemented at all other deposits.
The mine features an existing portal at Mammoth deposit, which provides an access to the Mammoth Deeps, Greenstone, Mammoth North, East and Pluto deposits. The Esperanza South underground mine lies to the south-west of the existing Mammoth workings and comprises an independent decline and supporting mine infrastructure.
The current processing unit comprises a conventional copper sulphide flotation concentrator. The existing equipment will be refurbished and a regrind mill will be added to allow the plant to process up to 1.7Mtpa of ore from multiple ore sources.
The concentrator will comprise a single toggle jaw crusher, feeding a coarse ore stockpile, and a comminution circuit consisting of a closed semi-autogenous grinding (SAG) and ball mills paired with a hydro-cyclone cluster.
The rougher flotation circuit will generate three separate rougher concentrates (high, middle, low grades), which will pass through three cleaner flotation stages. The concentrate will then be passed through the conventional thickeners for producing final copper concentrate.
The concentrate produced at Capricorn mine is proposed to be transported to the Port of Townsville in sealed half-height containers for export.
Infrastructure facilities at Capricorn copper project
The Capricorn copper mine will make use of the existing operating and support infrastructure including a processing plant, existing mine declines and development, site infrastructure and offices, as well as established power and water supply facilities.
Key players involved
Byrnecut was awarded the mining contract for the underground Capricorn copper project in December 2016. The contractual scope also includes the underground mine rehabilitation, pre-production development, and production.
AEC Group prepared the economic impact assessment (EIA) report for the copper mine.