Kennecott Concentration Mill

Hi Blog,

As part of our side trip to Kennecott and McCarthy, we scheduled a guided tour of the Kennecott Mines National Historic Landmark on Wednesday, July 13, 2016. After a hearty breakfast at the Kennicott Glacier Lodge, we joined our guide from St. Elias Alpine Guides. While there is an option to take a self-guided tour, the only way to enter the 14 story concentration mill and wander through it is with a guide.

The town of Kennecott was started in 1900 and expanded in stages until the mid-1920’s. By 1938, there were more than 100 buildings. When you look up at the mill, it looks more like a set piece from a Harry Potter movie. The only thing holding it to the side of the hill is magic.

We began our tour with a hike up National Creek. We entered what was once the top floor of the mill. We donned our hard hats and prepared to enter the mill.

When Kennecott was abandoned in 1938, the company hired someone to destroy the town. This entrepreneurial demolition man did take off the roof of the mill, but spent the rest of his time in Kennecott stripping the buildings of their copper wire and other valuable equipment to sell for his own profit before he fled into the northern wilderness, never to account for his unearned demolition or his recently liberated copper profits.

Shipping ore to Tacoma, Washington for smelting was expensive for Kennecott and required the copper ore to be concentrated for maximum profitability. The most economical process was gravity concentration, which is why the mill is built so high up on a hill side. Ore was delivered from five remote mine sites via a tramway. Ore cars were unloaded and the rocks began to make their journey through the building.  Here is the first shaft the rocks fell through:

Rather than taking the express chute, we opted for the stairs.

Once in the Mill, ore went through a series of crushers and sorters using gravity and water to move the rock from one process to the next.

Once waste rock was removed, ore was loaded into burlap coffee bags and stacked on open rail cars and shipped to the coast. Here Kathy examines one of the sorting beds to see if any copper was left behind.

We soon found ourselves back to street level. After the milling building, the next two stops seemed tame by comparison. We stopped at the leaching plant. Gravity concentration only works for high grade ore. Once all the good stuff was mined, they had to figure out how to get the copper out of low grade ore. They took gravel-sized pieces and soaked them in ammonia. This solution was then distilled and evaporated in order to separate the copper from the limestone. If the noise from the rock crushers didn’t get you, then the smell of the ammonia would. The large tanks were constructed in advance before shipping, taken apart and numbered, then shipped by train to Kennecott and reassembled.

Our last stop was the power plant. Kennecott had three different ways to generate power - waterwheel, diesel generators and a wood fire steam turbine. Steam and electricity traveled to outlying buildings and homes through “utilidors” or corridors built under wooden walkways, which kept them free of snow and ice in the winter.

After the tour, we got a chance to poke around in some of the other buildings. We were amazed to learn the company only gave workers and their families 24 hours notice that the mill and town were closing. There would be only one last train and they were pulling up the tracks behinds them.

We returned to the lodge for a late lunch and then took the shuttle down to the pedestrian bridge. From there we caught the Chitina shuttle and arrived at the Hotel Chitina just in time for dinner. Since the Hotel Chitina is one of the few places to eat in town, we ran into a number of folks we met in Kennecott. We enjoyed sharing experiences with them and finding out where they planned to travel next.  There was, as always, lots of conversation about Great White, which was parked outside the hotel.

And so ends another road trip. More adventure awaits in Haines!