this is another hoary old chestnut which has spluttered along for decades; there was extensive sampling and a trial drift there in 1978-80 ( the drift was driven by Cementation, if memory serves? )
I'll just say that if anyone succeeds in paying real wages for real jobs producing real product, more power to their elbows.
''the stopes soared beyond the range of our caplamps' - David Bick...... How times change .... oh, I don't know, I've still got a lamp like that.