The Iron Ore Dock in Marquette’s Upper Harbor is also known as the Presque Isle Dock.
The dock was built in 1911 and is still commercially active. Each year approximately 9.5 to 10 million tons of ore are shipped from this dock. The dock is owned and operated by the Cliffs Natural Resources. This steel-framed dock is 1,250 feet long and 60 feet wide, with the top deck sitting 75 feet above the water level. It contains 200 pockets, each of which has a capacity of 250 tons of ore, for a total storage capacity of 50,000 tons. Supporting the dock is a foundation of 10,000 wooden piles enclosed by a 12-inch thick timber sheet plank wall filled with sand.
After being mined the ore is crushed and the iron separated out with either a chemical or magnetic process. The iron is combined with a binding agent (a glorified cornstarch) and rolled into small balls roughly an inch in diameter. The balls are fed through a kiln and fired by temperatures exceeding 2,000 degrees F. The result is Taconite Pellets which are loaded on the ore boats and shipped. Most of the pellets shipped from the Presque Isle dock go to Algoma Steel in Sault Ste. Marie, Ontario the largest integrated steel mill. These pellets, which are roughly 70% iron, will be combined with coke and limestone at the mill to make steel.
The ore comes to the dock via railcars and is dumped into steel “pockets” or bins beneath the tracks. To load the boat, the chute is lowered to the open cargo hatch and a door at the bottom of the pocket opens, allowing the pellets to run into the boat shown in the picture. Loading time is variable, depending on the size of the boat and how prepared the dock is to load. Four hours is typical. Loading is the responsibility of the First Mate. It is important to load the ore in a proper sequence to avoid over-stressing the boat unevenly. Each chute (or drop of ore) is about 20 tons.