Unfortunately, while there may be a 100yr resource to be defined...

Unfortunately, while there may be a 100yr resource to be defined in the tenement area, E25 doesn't have a resource large enough to last 100 years if producing at 1.1Mtpa of output per year. If taking an average grade of 10% and concentrating it to 32% then even with 100% recovery rates 3.2x output volumes would be needed so ~3.5t would be needed for each year's 1.1Mt of output. 276/3.5 = 79 yrs. Recovery rates won't be 100% so the mine life including the use of inferred is something under 79 years.

E25 released the information below when doing their resource upgrade drilling. They ended up defining 130Mt at measured and indicated so just under half the total resource was M&I. This resource infill drilling was designed to last 20 years indicating that a resource in excess of 40 years was planned, if all inferred was also used in the mine life calculation.


Looking at the planned resource usage for the planned output, E25 have a fairly low recovery rate modelled within this 20-year estimate. I suspect what E25 have done is take the comparatively poor recovery rates from when butcherbird was operating and use those as a conservative estimate of future recovery rates for the life of mine calculation. Their expectation is they will exceed past recovery rates enabling the mine life on current M&I to be a few years longer but having been stung several times on optimistic estimates they are being conservative - the ore mining is the cheap piece of the overall project. If various improvements were to over-time get the recovery rate to 80% then the theoretical mine life using measured, indicated and inferred to a 32% product grade from a starting grade with output of 1.1Mtpa is 62 years. This assumes any element of the 274Mt not recovered from the ground is captured in the 20% recovery losses.

(274 * (10%/32%) * 80%)/1.1 = 62.3

Given the areas with potential manganese are yet to be drilled, the resource has the potential to expand to be 100 years (at 1.1Mtpa of output) but it isn't there currently and it would also be comparatively silly to waste precious cash resources now to drill out material that won't be used for decades.