The Savannah nickel-copper-cobalt mine is an underground mine located in the East Kimberley region of Western Australia. The project is owned and operated by Panoramic Resources.
Mining at Savannah originally commenced in 2003. The multi-metal ore body was initially mined through the open-pit method followed by underground mining for a period of more than 12 years before the mine was placed under care and maintenance in May 2016.
The Savannah project produced a total of 1.22 million tonnes (Mt) of concentrates containing 94,600 tonnes (t) of nickel, 53,000t of copper, and 5,000t of cobalt during this period.
Panoramic Resources released an updated feasibility study for recommencing mining operations at Savannah in October 2017 and decided to reopen the mine in July 2018. The feasibility study predicted production of 90,200t of nickel, 50,700t of copper, and 6,700t of cobalt over an estimated mine life of 8.3 years, with an estimated capital expenditure of £24m (A$40m).
Mining restarted at Savannah in December 2018, while the first concentrates from the mine were shipped to China in February 2019. The mining of the Savannah North deposit was started in March 2020. The Savannah mining operation was however temporarily suspended in April 2020 due to the outbreak of the COVID-19 epidemic.
Location, geology, and mineralisation
The Savannah nickel-copper-cobalt mine is situated approximately 240km south of Kununurra in the East Kimberley region of Western Australia.
The Savannah deposit is hosted within the layered mafic-ultramafic Savannah Intrusion, which is surrounded by aluminous metasediments and para-gneisses of the Tickalara Metamorphics.
The Savannah North deposit is predominantly composed of two distinct zones of sulphide mineralisation, namely the Upper Zone and Lower Zone.
The Upper Zone massive sulphide mineralisation is up to 8m thick and strikes east-west and dips moderately to the north.
The Lower Zone mineralisation is up to 15m thick and dips 50-60 degrees towards the northwest.
Ore reserves at Savannah nickel-copper-cobalt mine
The Savannah multi-metal mine is estimated to hold 8.02Mt of ore reserves grading 1.38% nickel, 0.64% copper, and 0.09% cobalt. The contained metals of the mine in proved and probable reserves are estimated to be 110,400t of nickel, 51,200t of copper, and 7,500t of cobalt.
The measured, indicated, and inferred resources at the mine are estimated to be 13.45Mt grading 1.56% nickel, 0.70% copper, and 0.10% cobalt.
Mining and ore processing
The mining operation transitioned from the main mine to the Savannah North mine in the first quarter of 2020.
The long hole open stoping (LHOS) mining method is implemented to extract ore at the underground mine. The extracted ore is trucked to the nearby process plant where it undergoes single-stage crushing, grinding in a semi-autogenous grinding (SAG) mill before passing through flotation, thickening, and filtering for the production of final concentrate products.
In June 2018, Panoramic Resources signed a new concentrate sales agreement with SinoNickel, a joint venture of China’s Jinchuan Group (60%) and Sino Mining International (40%), for supplying the entire concentrate output of the recommissioned Savannah project for a period four-years starting from 2020.
Financing for the Savannah mine restart
Panoramic Resources secured a £24m (A$40m) loan facility from the Macquarie Bank for restarting the Savannah mining operations in July 2018.
Barminco, a subsidiary of Perenti (formerly the Ausdrill Group), was awarded a £103m (A$200m) contract to perform the mine development, production, and haulage for the Savannah project over a period of three years in February 2020.
The consultants involved in the feasibility study for the project included Beck Engineering, Ozvent Consulting, Coffey Mining, and Cube Consulting.