Hi Saltpetie
Room and pillar mining would not be at the ‘cheap end’ of the mining cost scale. Somewhere in the middle perhaps. Block caving is probably the cheapest and open stoping somewhere close behind it.
Relatively, room and pillar would be materially more expensive than the above methods.
With respect to room and pillar, many factors drive the cost outcomes: the degree of mechanisation that is possible. The degree of ore continuity. The competence of the hanging wall.. the thickness of the ore.
Oposura does not exactly have lots of strike length so continuity not the best. Thickness is ok at times, but can be thin. Mechanised mining should be possible. Hanging wall competence - unknown at Oposura, but it can heavily impede an underground mining operation.
A big positive is that development costs will be low due to the direct access to the ore from the open pits.
I would expect that high cash flows will come from the thick high grade underground zones.
But where they are thinner and lower grade the cash flow will only be modest.
Personally I wonder if the exploration potential was so good at Oposura, why are they charging at great rate towards a scoping study? Normally the size of the ore body is determined fully before a feasibility is conducted. Getting the mine scale right (maximised) is such a huge factor in mine economics. The exploration extensions are close to surface - why not do another 3 months of drilling and see what is there? And then assess the project?
And can I ask you - why is there no geophysics to target new ore zones? There has been nothing apparent in the releases to date? Surely the zinc sulphides are near surface would stand out like a beacon?
Cheers
Gosouth
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