A mine dump, or waste rock dump, by definition consists of waste rock from a mine — whether it be an underground or surface mine — that has been dumped somewhere, usually quite close to the mine, sometimes even inside a surface or underground mine, so as to minimize motorized or track haulage costs."The briefest description of waste rock dumps is from Western Australia—all you need to know in two pages. [May not be original link; also condensed here to one page.] The most comprehensive description of a waste rock dump is in the EduMine course Design and Operation of Large Waste Dumps. In practice no definition is needed; simply see the picture on the front page of this review."
— Jack Caldwell, from Waste Rock Dumps, rev. 28 June 2006
|Old mine dump.|
Tailings should not be called mine dumps, either: they are the tails that have come out the back end of the ore processing plant; the heads went in the front end. Tailings (or tails) were once ore, not waste, or they wouldn't have gone into the mill for milling and then processing. They are usually found behind tailings dams (although not always). Tailings shouldn't really contain any ore, but sometimes — perhaps if the mill or recovery plant isn't operating properly or if the ore going into it is of an unexpected or unusual character — some amounts of the ore mineral may get through to form ore-bearing lenses behind the tailings dam. Sometimes — usually in the future when (if) the price has gone up, unless your mill is currently letting through too much unprocessed mineral all the time (therefore right now and also in the future) — the entire tailings mass may comprise a low-grade ore deposit. Many tailings deposits have been sampled or drilled as potential ore. Tails near Kalgoorlie have been mined; Eldorado Gold plans reprocessing of tailings at its Olympias, Greece, project.
|Mine dump inside old, inactive open pit.|
|Mine dump in fog at sunrise.|
One could also, perhaps, argue that the tails or tailings are now waste and therefore a mine dump, but I cringe at this idea, because there really is a specific name for that material: tails or tailings. Tails can become ore after their creation if mining technologies improve or if the prices of commodities contained within go up. One hopes that a mill isn't putting too much metal out in the tails; that usually implies a poor recovery rate, and poor recovery rates are usually unfavorable to profitable mining. And mining has to be profitable, or the individual mine owner or individual miner (yes, there are a few), the mining company, or the shareholders of a mining company would be better off putting their money into a bank or a mattress instead of investing in the mine.
|Old mine dump.|
I do get tired of hearing every single pile of rock near a mine being called a mine dump.