RE: IMPORTANT FACTORS FROM MINING.COM17 Sep 2020 04:05
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" Marigold is a large run-of-mine operation. After blasting the ore, it doesn’t need to be crushed or ground and can go directly onto the leach pad which significantly reduces costs. In the third quarter Marigold reported an AISC of $965/oz, after realizing a gold price of $1,207/oz.
Strip ratio
The strip ratio is the amount of waste rock, or overburden, that must be removed in order to get to the mineralized rock (ore). The strip ratio is calculated by dividing the thickness of the overburden by ore thickness. Eg. if the overburden is 100m thick and the ore is 50m, the strip ratio is 2:1. The lower a strip ratio, the more profitable the mine will be, since less material needs to be moved.
High-grade gold contained in narrow veins that snake through the rock can only be mined by excavating shafts and hoisting the ore to surface via low tunnels (drifts). This process is expensive, because digging deep requires a lot of material to be removed around the veins so that the mining equipment can access them. Consider a typical quartz vein that is 0.5 meters wide. At minimum another meter must be added to the vein to mine it. The width is now 1.5m. But logistically, in order to drill, blast, and muck the ore, the vein width must be stretched to 3m. This means the deposit, first estimated at 10 g/t, is now only 5 g/t because the gold has been “diluted” by the waste rock. Dilution can drastically affect the economics of mining the deposit. Rock that was originally estimated at $420 a tonne is now worth $210/t – cutting the internal rate of return (IRR) and the net present value (NPV) in half.
Underground mining is highly sensitive to gold prices, considering the high operational costs. "
OMI HAS THE ADVANTAGES