@Greenflint It will more than likely be LG (low grade) and MW (mineralised waste) stockpiles that have just been built up over time, so it could be anything from 0.3 g/t to 0.8-1.0 g/t material. The fact that they used the word "historical" suggests they have purposely been left unprocessed in favour of higher grade ore by previous operators. Common practice.
Since the capital is already sunk i.e. all the hard work has been done in drilling, blasting, mining etc. and getting it to the ROM pad, it is cheap to process, and will generate cashflow at these gold prices.
