RE: SP15 Oct 2022 10:45
Parkez,
The cutoff grade is the economic break even point. Grades above it make money and would be treated as ore, grades below it lose money and would be treated as waste. Cutoff grades vary from mine to mine and during the life of a mine so don't believe anyone who tells you that just because you can mine 0.8 g/t somewhere in Africa or Australia then you can mine it here in Ireland.
The company used 1g/t for its JORC resource so you'd have to assume it is reasonable unless and until the company provides justification to change it up or down. So, on current information, over 1 g/t = ore, under 1g/t = waste. The company is reporting waste intersections and trying to tell you it is good news.
Consider this for your Saturday morning:
Company reported recovery of 80% at company reported average resource grade of 2 g/t means 1.6 g/t recovered, 0.4 g/t unrecoverable. 1.6 g at $1,600 per ounce is worth $82. So, 2g/t rock = $82 per tonne.
At the 1g/t cutoff, 0.4 g/t is still unrecoverable so only 0.6g/t recovered (60% recovery). 0.6 g/t at $1,600/oz is $30, so that gives you your breakeven cost so long as you keep your operating costs at or below $30 per tonne. Average margin for a 2g/t resource on this basis is $52 per tonne.
At 0.8 g/t only 0.4 g/t are recoverable = 50% recovery. 0.4 g/t at $1,600/oz is only $20 rock. Mining 0.8 g/t would incur a loss of $10 per tonne. You'd have to somehow bring your costs per tonne below this level to make that grade economic.
Anyone who tells you those are good grades is taking the **** out of you.