The North East and Larsens Mines are located 5 km north of Murrawombie.

Copper mineralisation at the North East Mine is hosted by weakly chlorite altered and silicified schist in a massive to banded pyrite – chalcopyrite lens that dips moderately to the east.

A higher grade core to the mineralisation is continuous across strike and plunge having a strike approximately 100 m and a width of 10 m.

Economic mineralisation strike is in the order of 175 m with a horizontal width averaging 30 m. The deposit is open at depth and resources, limited only by drilling.

Copper sulphide mineralisation, primarily chalcocite, at the adjacent Larsens Mine is hosted by weakly chlorite altered schist in three discrete, massive to banded pyrite – chalcopyrite lenses that dip steeply to the east and plunge moderately to the south – east. The central lens is the largest defined to date and comprises two sub parallel lenses each several metres thick with strike lengths of 40m.

The deposit is open at depth with very limited drilling. Mining operations have recommenced to establish underground drilling positions for resource extension.

Mining at the North East Decline is undertaken using longitudinal open stoping with partial rock fill, currently at a rate of 480,000 tpa. North East Decline ore is trucked to the processing plant at Tritton.

Mine Design Criteria
- Declines and Cross cuts 5.5 mH x 5.5 mW
- Decline gradient 1:7
- Decline curvature 15 m
- Decline standoff 40 m
- Decline access Hartmans pit
- Ore drives 5.0 mH x 5.0 mW
- Level interval 20 metres

The crushing circuit comprises an ore bin with a fixed 800 mm aperture grizzly, feeding ore via a vibratory feeder to a Kemco S7N single toggle jaw crusher with a feed opening of 1.22 x 1.02 m.

Crushed ore of P80 100mm is conveyed to a 6,000 tonne stockpile where it is reclaimed via three vibrating feeders.

Grinding comprises an ANI Ruwolt fixed speed high aspect 6.7m dia X 2.13, 1500 kW SAG Mill, discharging via a trommel screen to the secondary grinding circuit. Lime is added at the SAG to target pH 10.5 for pyrite suppression.

Secondary grinding comprises a Marcy 3.81 m dia x 5.18 m 1250 kW ball mill operating in closed circuit with 500 mm dia Linatex hydrocyclones. Cyclone overflow discharges to two parallel Metso Vertimills (VTM800STD) installed as part of the TEP and shown in the foreground of the lower photo.

The grinding circuit produces a cyclone overflow product of P80 75 µm at 30 to 35% w/w solids.

The tertiary cyclone overflow feeds two 50 m³ Wemco tank cells (installed as part of the TEP) in series for primary rougher flotation.

Regrind is achieved by a 2.0 m dia x 3.4 m 150 kW ball mill in closed circuit with Cavex hydrocyclones. The underflow reports to regrind and overflow to scavenger cleaner, rougher cleaner and final conc.

The Tritton flotation circuit produces a copper concentrate typically with 25% Cu, <1 g/t gold and 30 g/t Ag from a mill feed of 2.1% Cu, 0.15 g/t Au and 6- 7 g/t Ag.

Copper is recovered by cementation from the residual acidic copper solutions circulating in the Girilambone heap leach pads.