RE:Would a mining concern install torches in the summer?What kind of winter are you talking about ?
Schefferville was a real winter and they did shut down, however the shut down was related more to the shipping season than to the mine. No processing other than screening took place at the mine but the seaway was closed as everything went up the lakes to the steel mills.
Labrador City started +/- 10 years after Schefferville. Mine and processing were on site and shipping initialy went up the lakes too. The only shut down that I recall, other than strike situations, was in 1978 when the market was very bad and there was a shut down in the summer to balance inventories with demand. Shutting down in the winter is a no-no as everything will freeze up and damage will occur only to be exposed when you try and restart. Heating plants which are not producing is a waste of money. Having to add heat to a pellet plant is an oxymoron.
Note that when the time to install plasma torches comes, after all the electrical work has been completed, it may very well be a plug and play effort added to a scheduled maintenance shut down. This will happen most likely be as soon as possible, season be dammed. IOC Lab City has 6 production lines. Shutting down one at a time would not be a problem during any season.
Note that pouring concrete at -30º C is not extraordinary practise at Lab City.
The real ansewer to your question will depend on the circumstances of each individual plant.