The Bannockburn deposit is located along the western margin within the central portion of the Norseman-Wiluna greenstone belt. Locally the project area is dominated by an extensive sequence of tholeiitic, high-Mg and komatiitic basalts with intercalated sedimentary and intermediate volcaniclastic horizons. Dolerite and gabbro sills intrude the sequence. The deposit is complex with multiple controlling factors. The gross geometry of the deposit is controlled by the Bannockburn fault, a steeply dipping NNW trending fault that is continuous over at least 2.3km on the western margin of the orebody. The fault separates an ultramafic unit in the west from the Bannockburn host sequence in the east. It dips steeply east, rolling to vertical and steep west dipping in the northern part of the orebody. The Bannockburn fault is effectively the western boundary to the orebody with very little mineralisation penetrating the western side of the fault. The Central fault which hosts the Central orebody has a shallow northerly plunge and is the orebody on which the majority of the underground workings is focused. There are a series of steeply east dipping lodes in the hangingwall of the central lode; these are interpreted as either tensional veins of reverse faults with shearing present along the veins. Black graphic shale units present within the stratigraphy have acted as a localised control on the mineralisation. The black shale units have taken up some of the deformation with strat ........

The Bannockburn deposit is amenable to mining by both open pit and underground methods. The deposit has been mined by open pit and underground methods historically. There are reasonable grounds to assume that in the future this deposit will again be mined by conventional open pit load and haul operations. Mining method to be employed at Bannockburn deposit is conventional open pit mining with a hydraulic excavator, dump truck fleet, and drill and blast activity. The class of excavator employed is similar to other open pit mining operations. Bannockburn reserve pit is designed as a large pit and will be mined in several stages to improve the stripping ratio. The Reserve pit will be mined such that it meets the operation efficiency, safety and production rate. The mine is currently on ‘care and maintenance’.

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.

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