TALISON GREENBUSHES PTY LTD

Geology

The tantalum, tin and lithium minerals are derived from rare metal pegmatites dated radiometrically at 2.6 billion years.

The two main ore zones within the pegmatite are the albite (feldspar) zone containing tantalum/tin minerals and the spodumene zone containing high grade lithium minerals which generally occur in enriched zones on the hanging wall of the principal pegmatite.

The main pegmatite orebodies occur along a strike length of 3.5 kilometres and generally dip to the west at a depth of 45-50 degrees.

Mining

Historically mining started in the alluvial washes in the creeks around Greenbushes and later moved to the weathered pegmatite. Today, mostly fresh, unweathered pegmatite is mined for tantalite and spodumene.

Open Cut:
The pegmatite is currently mined from two pits in the Central Lode zone. Both pits use a drill and blast method of mining. Five and ten metre benches are blasted using explosives emulsion.

The broken material is removed using hydraulic excavators and 90 tonne dump trucks. Ore is taken to the Run of Mine (ROM) pad where it is stockpiled according to mineralogical characteristics and grade. Tantalum and lithium ores are stockpiled separately.

Waste material is trucked to designated areas within the site where it is contoured and replanted as part of an ongoing rehabilitation plan.

The Cornwall Pit (tantalite), situated immediately south of town, was completed in 2003 at a depth of 270 metres.

Underground Mining Operations:
In 2001 an underground mining operation commenced at the base of the Cornwall Pit to access a large high grade tantalum deposit. The underground mine is currently under care and maintenance.

The underground operation was developed through a 5.5 metre x 5.5 metre decline with a gradient of 1:7 (1 metre down for every seven metres horizontally) which is twice as steep as Hester Hill just north of the Bridgetown townsite.

The dimensions allow for easy access by 40 tonne dump trucks, loaders with 15 tonne capacity, 4WD utilities, explosives charge wagons and a range of service equipment.

Twin boom jumbo drilling machines were used to drill seventy 3.5 metre holes per face which were then charged with explosives and blasted in a set sequence. Fifteen metres of tunnel was excavated each day.