Australian copper producer Sandfire Resources has extended the operations at its DeGrussa copper-gold mine located 900km north-east of Perth in Western Australia until mid-2021.

The new mine plan is expected to allow underground mine production at the rate of 1.5Mtpa and mine development at around 7,000m per year until early 2017.

The extension of mine life is supported by the addition of new underground mineral resources.

Sandfire has recently added Conductor 4 deposit to its mine plan. The deposit is said to have two million tons grading 4.5% Cu and 1.5g/t Au for 88,000 tons contained copper and 94,000oz contained gold.

Based on mining depletion to December 2014, the ore reserves at the property total around 343,000 tons and 368,000oz of contained copper and gold respectively.

Sandfire managing director Karl Simich said: "Underground drilling in and around C1 and the deeper C4 and C5 deposits will be an increasing focus for Sandfire in 2015 as more drilling positions become available from the expanding underground infrastructure.

"In particular, recent underground drilling has returned strong grade intersections outside of the known Ore Reserves, identifying potential feeder zones in the footwall of the C1 deposit.

"Subject to further drilling, this work could lead us closer to finding the underlying volcanic source of the DeGrussa deposits, which would be a very significant development."

Work on Conductor 4 is underway with plans for first stope production in early 2016. Conductor 5 diamond drilling will continue with expected C5 Mineral resource update in the first half of 2016 with first stope production from C5 in 2017.