"How wide do you think the development drives are?
I was thinking 4M based on a mentioned reef face sample of 3.7M, although I assumed the sample was
horizontal.
If we have a drive width of 4M and reef widths fairly close to that (even half) would these reefs be economic based on the grade, even with scalping and stoping?"
I would think you are probably correct the drive width would be 4 to 4.5 metres wide and probably 4 to 4.5 metres high.
A 2 metre wide ore width providing it has the grade can be very profitable (have a look at DRM's Andy Well).
However the strike length is also important to get to the magical 1000 ozs per vertical metre ie if you only have a short total strike then the Decline CAPEX costs (not drive CAPEX) become disproportionally high compared to the amount of ozs that can be pulled out of the mine.
Lets say the drive is 4 to 4.5 metres high then they drill vertically (uphole stope) to the level 16 metres above then set their charges and can normally remove a 2 metre wide section without excessive dilution providing the dyke (vertical lode) does not pinch and swell excessively between the levels.
Scalping may be beneficial on drive ore but providing there is no overblast it may not be necessary for the ore removed between the levels.
The sludge hole testing I thought was to test an offset splay reef not sure of its relevance when in a drive given how visibly evident the quartz seams are
Just my thoughts and not a mine engineer.
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