A40 losing since 5 years, TAW now in their spiral!, page-68

it is a bit general I admit. However it is a good assumption to assume that it costs almost the same to produce 100kt per annum as it does to produce 155kt per annum because the number of employees are exactly the same and the power required is the same (gen sets run 24/7). The mining cost is slightly lower because (you hope) the mining contractor sends all the sub 0.4% to waste. The plant operating cost will be virtually identical because everything is running 24/7 and in fact when you run low grade or as a40 is doing you fill up the slimes dam and the tailings stockpiles faster and save a pittance on lower con transport costs