RE:one year stockpilePhilly- There are companies that do this, under slightly different operating parameters, I don’t think MMb would be doing this. Vale, for example, I think did this for a time with their nickel out in Voisey’s Bay, Newfoundland. They dug it up @ Voisey’s and shipped the raw ore (via train) to their concentrator in Sudbury, Ontario. Shipping costs are extremely high, but it is still cheaper than building a whole new processing plant. (Then I think the Newfoundland gov’t stopped that, and insisted they process the ore in Newfoundland to create jobs). This is usually only financially viable if the company has an operating mill somewhere closeby that can process the ore, thereby keeping the revenue within the company. Selling raw ore to a 3rd party to crush/process is rarely profitable, unless the concentrations are incredibly high. Additionally, you would only do this so you could make money without having to spend enormous capital on a processing plant. As MMB has a plant that is ramping up, and in the future they would be able to process this high-grade ore, I would think they are keeping it in reserve stockpiles, and will reclaim it later.
Typically when you are commissioning a mine you will use lower grade ore, because the equipment is not able to handle it’s full throughput, and the process is not dialled in, so a lot, a lot of ore is lost. You want to lose the garbage, not the good stuff. If they are doing advance mining underground, this means they will be boring through low grade ore to get to the high grade reserves. They will hoist the stuff from the advance, and use it to commission the plant. Also, they are doing open pit. So, let’s say the high grade reserves are …I don’t know, 30m underground, they will use the excavated 30m of low grade material to commission the plant. So that by the time they get down to the high grade near-surface reserves (open-pit), and by the time they get to the high-grade underground reserves the equipment in the plant will have been conditioned, and is ready to be pushed to it’s limits so they can get the maximum out of the high grade ore. The Cinto Colorado tails are high grade, they will process those once they are up to nameplate capacity.