I was doing some due diligence on Alamos Gold (AGI) today and was impressed by how well they seem to have made their deep underground mining as efficient as possible. I suggest watching the video presentation on their Young-Davidson Mine, which is located at the bottom of this page and called "Lower Mine Expansion:"
www.alamosgold.com
Most of their ore harvesting in the mine now takes place at depths up to 4,500 feet below the surface. They use remote-controlled tractors to carry the ore to rock crushers, which have been built at that depth. Then, two lifts carry the crushed rock to the surface to complete the processing to produce the raw gold. They built 600-meter-long tunnels to connect the mining scopes to the vertical lift shafts. As you can see in the video, the ore elevators lift the rock all the way to the surface, several tons at a time. I guess that means that when they built the lifts, they had workers installing tracks, guidelines, and supports while suspended above a hole that was over 4,000 feet deep!
Apparently, they also use the lifts to transport workers and equipment down to the lowest levels of the mine. Imagine riding an elevator down over 4,000 feet without stopping. Miners must have nerves of steel. The mine operates 24-hours a day, 7 days a week with 350 employees, who work 10 1/2 shifts, five days on, then four days off, then four days on, then five days off, then repeat.