Piece of Slag

Mining is a messy business, an industry that discards an exceptionally large amount of waste product for such a minuscule amount of actual copper. First there’s the copper-barren rock that remains after the copper is removed, usually stacked up in large towering piles up on the surface. Then there’s the fine gravel left over after the milling process, an enormous amount of material that usually ends up encompassing large volumes of space in an adjacent lake. Finally there’s the smaller – but still rather significant – amount of molten rock skimmed out of smelting furnaces during the final step in the copper purifying process. Known as slag, this dark amorphous waste product was poured into tram cars and sent out to be dumped into sprawling piles of their own, until cooling to form massive black tumors across the landscape.

Of course that was the modern efficient method to remove slag from the premises. In the old days something a bit more crude and cumbersome was the norm, in the form of slag pots like seen in the photo above. This iron pots on wheels would be wheeled up to a furnace and filled with the molten rock. The pot would then be wheeled out to a dump pile and manually dumped before being wheeled back in to repeat the process.


You can clearly see this process in person with just a casual tour of the Quincy Smelter’s slag piles, where you’ll notice more then a few large boulders of slag that have a remarkable resemblance to those iron pots on wheels of old. To think that an old Quincy employee wheeled a pot of slag out to this spot a century ago and it still remains to this day for us to see it blows my mind. Of course, that fact that it does still remain makes a rather strong statement about the copper empire’s more nefarious legacy.

Discuss…

  1. Strange they did not grind it up and use it for road material, mine rock seems too harsh on a car’s tires. Anyways, that what they did in my Dad’s hometown.

  2. JSU,

    They did try slag for road material, but it was way back when tires were rather delicate and the glass-like nature of slag was very hard on the tires. At least that is the oral history I heard from various Copper Country old-timers. Using slag for road material might meet with more success with modern tires.

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