Taconite Mining: The Reserve Mining Company
The Reserve Mining Company operated out of Babbitt and Silver Bay, Minnesota from 1955-1980. Reserve began disposing of taconite tailings from their processing plant into Lake Superior in 1955. Over 500,000 gallons of Lake Superior water was utilized every minute for the disposal of these tailings. Overall, Reserve disposed of 67,000 tons of taconite tailings each day, which is approximately 547,500,000 tons of tailings disposed of in Lake Superior in the 25 years of Reserve’s operation and 4,562,500,000,000 gallons of waste-water. Both the environment and the health of the Northshore populace was (and still is) affected by the taconite waste (Duluth, Beaver Bay, Two Harbors, Superior).
In the 1860s, iron deposits in Minnesota were discovered and mapped. The Biwabik Iron Formation in northern Minnesota is 120 miles long and 250-700 feet thick. The targeted ore in Minnesota’s Mesabi range was high-grade hematite, or “natural ore” (rocks with 50% more iron). Lower grade taconite (25-30% iron) is part of an iron formation that has not been oxidized and enriched by natural processes. These are the rocks surrounding and below the pockets of high-grade ore. Natural ore could be taken from these deposits and directly shipped across the Great Lakes and eventually to steel mills in the eastern United States. More that 85% of U.S. iron ore used in World War II was derived from open-pit hematite mines in the Lake Superior region. In time, however, this high-grade ore became less abundant. Around the end of the Vietnam War, companies made the switch to low-grade ores and pellets. Mining natural ores was eventually phased out.
Utilizing taconite proved to be challenging. Fine-grain taconite required extensive grinding to separate the magnetite grains from non-ore minerals. In addition, the fine-grain magnetite concentrate was difficult to ship and to use in blast furnaces. At that time, 70% of the taconite ended up as tailings that needed to be disposed of. Throughout the first part of the 20th century, a method known as gravity separation was utilized to process the taconite. In the 1940s, a new taconite processing method was developed using magnetic separation and pellet shipment. By 1947-8, the Reserve Mining Company opened its processing plant and began disposing of tailings into Lake Superior.
History of Taconite Mining
In the 1860s, iron deposits in Minnesota were discovered and mapped. The Biwabik Iron Formation in northern Minnesota is 120 miles long and 250-700 feet thick. The targeted ore in Minnesota’s Mesabi range was high-grade hematite, or “natural ore” (rocks with 50% more iron). Lower grade taconite (25-30% iron) is part of an iron formation that has not been oxidized and enriched by natural processes. These are the rocks surrounding and below the pockets of high-grade ore. Natural ore could be taken from these deposits and directly shipped across the Great Lakes and eventually to steel mills in the eastern United States. More that 85% of U.S. iron ore used in World War II was derived from open-pit hematite mines in the Lake Superior region. In time, however, this high-grade ore became less abundant. Around the end of the Vietnam War, companies made the switch to low-grade ores and pellets. Mining natural ores was eventually phased out. 
Utilizing taconite proved to be challenging. Fine-grain taconite required extensive grinding to separate the magnetite grains from non-ore minerals. In addition, the fine-grain magnetite concentrate was difficult to ship and to use in blast furnaces. At that time, 70% of the taconite ended up as tailings that needed to be disposed of. Throughout the first part of the 20th century, a method known as gravity separation was utilized to process the taconite. In the 1940s, a new taconite processing method was developed using magnetic separation and pellet shipment. By 1947-8, the Reserve Mining Company opened its processing plant and began disposing of tailings into Lake Superior.
Current Connections: PolyMet
The Reserve Mining Case is relatable to a current and local mining issue: PolyMet’s proposed NorthMet Mining Project in northern MN. While the NorthMet mine would be a sulfide mine, its operation faces the same environmental justice issues as the Reserve taconite mine. Since 2004, PolyMet has been working through the environmental review process and moving forward to acquire permits to begin construction. They want to utilize open pit copper, nickel, cobalt, and precious metals mines as well as refurbish the old LTV Steel Mining Company plant, construct a new hydrometallurgical facility, and construct a new tailings basin. The major concern for this potential mining activity is acid mine drainage.
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