The graphite mineralisation at Siviour is hosted within a sequence of schist, micro-gneiss and metasedimentary rocks. The mineralised zone has a simple tabular geometry and the main portion of the deposit is oriented east-west.

The geometry of the Siviour Graphite Deposit is generally flat-lying, with thick, flat, gently folded graphite mineralisation sitting from within 5 m to 15 m of surface. This orientation facilitates a single shallow mining design that can be mined via conventional open pit mining methods.

The DFS pit optimisation and mining study resulted in a mining schedule conducted in 14 stages mined over a period of 26 years. Mining commences in the southern portion of the orebody to permit mining of a higher-grade corridor in the mine’s first year.

The proposed mining method is conventional truck and shovel open pit bench mining. Free digging in alluvial material makes up around 15% of all overburden, while drill and blast is required for all other lithologies.

Initially, mining will be conducted on a 24-hour basis in order to access high grade ore as soon as possible, before dropping to day-shift only in years 2 and 3. Mining will return to a 24-hour operation in Year 5, coinciding with the process plant expanding to 1,650ktpa capacity.

The DFS considers the construction of two 825ktpa processing plants, for a total processing capacity of 1,650ktpa, with the construction of the second plant to potentially be funded from projected cash-flows derived from graphite sales from the first plant. The plants are based on identical designs.

Crushing
Crushing will occur in two stages. In the first stage, a primary jaw crusher will crush ore from the pre-blended ROM pad, and crushed product will be conveyed to a scrubber. The scrubber oversize will be crushed in a secondary pebble crusher and conveyed back to the scrubber feed. The primary crushing circuit operates at higher capacity than the mill to allow for a crushed ore stockpile.

Grinding
Crushed, scrubbed ore will be conveyed to a primary rod mill to achieve flotation feed of P99 425 µm. The mill discharge will be collected in a hopper before being pumped to a vibrating screen, with oversized material recycled back to the rod mill. The fine material bypasses the primary mill to avoid overgrinding.

Flotation and Regrind
Flotation and regrind circuits contain desliming, roughing, scavenging, seven stages of cleaning and four stages of regrind. The cleaning circuit includes screening of concentrate at 300µm after the second cleaning, with the coarser flake material reporting direct to filtration and drying. The finer material will pass through additional regrind and cleaning to increase purity. The circuit is designed to optimise coarse flake graphite retention at a minimum purity of 94% to 96% TGC.

Dewatering and Product Handling
The final concentrates will be filtered, dried and screened into five size fractions (+300 µm, +180 µm, +150 µm and -150 µm). Concentrates will then be directed to bins and bagged into one tonne bulka bags by product specification.

Tailings
Tailings, including slimes and flotation circuit tailings, will be directed to a tailings thickener for dewatering prior to being pumped to the tailings storage facility. Tailings thickener overflow will report to a process water tank for water recovery and reuse.