MEADOWBANK GOLD MINE, Nunavut—Gold miner Alain Belanger contends with 75 mile an hour winds, winter temperatures so cold they have cracked the steel on his 287-ton excavator and white-out blizzards that can halt mining for days.

This open-pit mine west of Canada's Hudson Bay has had such steep construction and operating costs—flying workers in and out, stocking a year's worth of food, employee turnover and battling snow drifts that can reach eight feet—that the project is unlikely to break even over the long haul, Agnico-Eagle...