Mining

The Rhyolite Ridge deposit is amenable to low-cost, open-pit mining methods. The Mineral Resource outcrops over a 3 km strike length along the western margin of the South Basin and generally dips gently to the east.

The thick (>20m) lithium-boron (Searlesite) mineralisation is very consistent along strike and down dip. The host rock is competent but relatively soft (hardness of 3.5 on Mohs scale).

Mining studies have shown the potential for higher cashflow in the early years by targeting higher lithium grades in the start-up phase of mining.  This is shown in the table below where the first 15 million tonnes mined are at a grade of 1,957ppm lithium and 1.12% boron.  The strip ratio is lower as the early stage of mining follows the outcropping (at or near surface) mineralisation along strike.

Key Outcomes of August 2018 Mining Study

Pit Shell

 

15Mt

 (Start-up Pit)

34Mt

Pit

92Mt

Pit

Tonnage of Mineralisation

Mt

15

34

92

Strip Ratio

t:t

4.8

5.9

5.7

Mined Grade – Lithium

ppm

1,957

1,901

1,735

Mined Grade – Boron

%

1.12

1.38

1.23

Contained Lithium Carbonate

kt

153

328

850

Contained Boric Acid

kt

941

2,547

6,461

Footprint of pit

sq. mile

0.32

0.43

2.57

Note: Each consecutive pit is inclusive of the of the previous pit.  The total mineable quantity is 92Mt. 

The above table is based on only the Indicated Resource for the lithium-boron (Searlesite) mineralisation.

The lithium-only (clay) mineralisation in the Mineral Resource is excluded as it is likely to require different processing. Testwork on the lithium-only mineralisation has not yet been completed, but it is reasonable to assume this mineralisation will be stockpiled for potential future processing.

Detailed mine planning is continuing as part of the PFS process and hence the above outcomes may change with further engineering and updated information.

 

Rhyolite Ridge

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