Thunderbox is a mesothermal lode gold deposit located at the southern end of the Yandal greenstone belt in an area where several major shear zones converge and join with the Perseverance Fault. The shear zone dips at 30° to 60° WSW, with the exception in the vicinity of the mineralisation, where the shear is vertical to steeply dipping. Mineralisation is hosted by strongly deformed, silicified and carbonate altered albite-quartz porphyry in the hangingwall of the shear zone. The shear juxtaposes foliated basalts and intrusive porphyries in the hangingwall against sedimentary rocks in the footwall. The zone of shearing is over 200m wide. An ultramafic unit occurs within the shear, in the footwall of the deposit and is attenuated along the shear. At the known extremities of the mineralisation, interpreted as a pepperitic apron, the porphyry host is less continuous and interchanges with mafic volcaniclastics. The main gold related hydrothermal alteration assemblage comprises quartz-ankerite-arsenopyrite- pyrrhotite-galena and gold. This assemblage has been overprinted by a retrograde chlorite- epidote-white mica-biotite-quartz and pyrite assemblage. Synmineralisation veins have a continuum of vein textures ranging from laminated to pseudo-breccias. Throughout the Thunderbox Deposit, elevated grades occur within southerly plunging ore shoots that are more evident in the lateral extents of the orebody. Whilst the shoots persist centrally, the gold distribution is for more unifo ........

Mining method employed at Thunderbox mine is conventional open pit with hydraulic excavator and dump truck fleet, and drill and blast activity. Thunderbox Reserve pit is currently in operation and designed as successive cutbacks to achieve final life of mine Reserve such that it meets the operation efficiency, safety and production rate. Appropriate mine schedule, operating cost and lead time have been considered to maintain efficient mining operations. A minimum mining width of 25m has been adopted for the primary excavation fleet. Where ‘pinch-points’ occur or “Good Bye” cuts are considered at the base of the pit, it is assumed that a smaller or more versatile excavator will be employed. The practice is very consistent across all open pit operations and reflects the suitability and efficiency of the mining performance. At Thunderbox, open pit mining continued with D Zone pre-strip and the installation of key infrastructure at Otto Bore to support open pit mining operation.

The process consists of a double toggle jaw crusher followed by a SAG and Ball milling circuit.

Metso Outotec has been chosen to supply its Premier SAG Mill for Northern Star Resources’ Thunderbox gold mine expansion. The expansion should double the throughput of the Thunderbox operation.

- subscription is required.