RE: RNS31 Aug 2021 12:53
Haha sorry FK. Its good to see someone born locally taking an interest. It's just difficult to separate out the mindless ramping that often goes on here. I'd really like to see this succeed, and in fact I believe it will, but one has to be realistic, especially if considering investing.
"As for the technicals, what are considered an attractive % mineralisation for Cu, Sn and g/t for Ag?"
It really depends on all these modifying factors that I was talking about earlier; width, depth, dip, ground conditions, metallurgical recovery factors, etc. There is no one set of numbers that you can boil it down to. But, basically the best way to go about this is to convert the % Sn, Cu or Ag (g/t) into a value per tonne of ore. So 1% Sn is... about $300/tonne. Take 65% recovery/net smelter factor etc, and you have say $200/tonne. On a 3-10m wide vein, you could estimate total costs at under $100/tonne, on a 1-3m vein, maybe up to $150/tonne, depending totally on scale. So you can see, in order to make a decent margin, on a small individual deposit typical of the area, you need either an (unusual) 3-10m wide vein of 0.8-1% Sn, or a normal 1-2m lode of 1.2-1.5% Sn lets say. Also remember, if you want to access a deep deposit and pump a massive old mine out, then your going to need a very large margin & a lot of reserves, to pay off the capital. Rule of thumb, copper is worth 1/3 of tin, so 3x as much required. All very rough!
The upshot of it all is, you need quite a large critical mass in terms of resources and reserves to make a project like this work. It might be possible to accumulate several different deposits, accessed from either South Crofty or the Wheal Maid decline, and together they will provide enough optionality and critical mass to be economically viable. There is already a large resource base at Crofty of high grade material, but its deep and high capex. All they need is a small high grade, easily accessible deposit, to start them off for a couple of years. Easier said than done of course, but they have the money to go drilling, they are going to have a crack at this on a scale no one else has tried for a long, long time.