The Reserve Mining Company
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.
1880s: First shipments of direct shipping ore from MN
1900: Gravity separation necessary for some ores
1940: 50% of all ore shipped from MN requires processing
1940s: Taconite processing method developed (magnetic separation and pellet shipment)
1947-1948: Reserve Mining Company opens taconite processing plant and disposes of tailings in Lake Superior
1955: First ore processed by Reserve Mining
1968: Taconite pellet shipment rate exceeds all other iron ore shipments from MN²
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.1-Michael E. Berndt and Brice C. William, "The origins of public concern with taconite and human health: Reserve mining and the asbestos case," Regulatory Toxicology and Pharmacology 52, no. 10 (2008): S31-9.
2-Berndt and William, "The origins of public concern with taconite and human health: Reserve mining and the asbestos case."