Taconite is a
low-grade iron ore. In older days when richer
ores were more common and easier to
mine, taconite was considered a waste rock by miners. However as other types were depleted, taconite became a valuable
resource to obtain iron from.
Researchers headed by Dr. E. W. Davis at the University of Minnesota worked for years to develop a method of extracting iron ore from taconite rock. Finally, scientists discovered how to make rich taconite pellets.
How to refine taconite
- Taconite is an extremely hard rock which must be blasted into small pieces with dynamite, usually in strip mines.
- The pieces are scooped up by giant shovels, some of which can hold up to 85 tons of rock. The rock is placed into giant dump trucks which can hold up to 240 tons of taconite. The trucks take the taconite to train cars or a processing plant.
- At the processing plant the taconite is crushed by rock crushers until it is about 1 cm diameter chunks. It is then mixed with water and ground until it becomes a fine powder.
- Powerful magnets separate the iron ore from the rock. The leftover rock, called "tailings," are dumped into "tailing basins" or "tailing lakes." The iron ore is now called concentrate.
- The wet taconite powder, or concentrate, is combined with clay and rolled into small marble-sized balls inside giant cylinders called pelletizers. The balls are then heated to white-hot temperatures and become very hard. When finished these are called taconite pellets.
- Finally, the taconite pellets are loaded onto giant ore boats which travel to big steel-manufacturing cities like Chicago, Gary, Indiana, Detroit, and others.
Taconite generally comes from the
Mesabi Iron Range (aka
The Range /
Iron Range) in northern
Minnesota, northwest of
Duluth, MN and near
Hibbing. For many decades taconite mining formed the economic backbone of the whole region, until steel prices crashed in the
1960's.
In Minnesota, Reserve Mining was the key employer which many thousands of people depended on. When Reserve Mining went bankrupt in the 1970's, the area all the way from Hibbing to the shore of Lake Superior was thrown into a recession it's still shaking off today.
On the North Shore of Lake Superior today, there are many giant taconite processing facilities and docks. In Duluth, Two Harbors, MN, Silver Bay and Taconite Harbor, MN, massive docks and buildings now operate at lower capacities than their peak, but still ship out iron ore. At Taconite Harbor, the facility is also used as a power plant for the area. Now most docks are operated by LTV Steel, although Bethlehem Steel and Hibbing Taconite are also key employers.
Sources:
Minnesota Dept. of Natural Resources: http://www.dnr.state.mn.us/minerals/digging_minerals/taconite.html
My wise mother from the North Shore