2014-07 Solving mine drainage problems at the Soudan Mine The final? answer.
Presented at the 2014 American Society of Mining and Reclamation Conference
June 2014, Oklahoma City, Oklahoma
Paul Eger, Global Minerals Engineering LLC, Hibbing, MN
Peggy Jones, Doug Green, Bob Forder, American Peat Technology, Aitkin, MN
The Soudan Mine, in northern MN, was a producing iron ore mine from 1882 to the end of mining in 1962. In 1963, the mine was donated to the State of Minnesota and became a state park in 1965. Since that time it has become important as a scientific research center and popular tourist destination. Water discharging from the mine contains elevated copper and cobalt and treatment is required. Since 2009, the water has been treated with a commercial ion exchange resin based system that includes flow equalization tanks, bag and cartridge filters, another flow equalization tank (break tank), a carbon tank and several ion exchange tanks. Although effective, the system’s high cost, inefficient removal of suspended material and substantial maintenance have been ongoing and troublesome issues.
In November 2012, a pilot test was initiated using a peat based sorption media (APTsorb™ ). This media is produced from raw reed sedge peat through a patented carbonization process which produces a hardened granular ion exchange material. The granules are uniform, have a high hydraulic conductivity and maintain the high metal affinity of natural peat
Mine water was pumped through the media without any pretreatment. Copper input typically ranges from 30 – 60 ug/l but concentrations increased to a maximum value of around 300 ug/l in the summer of 2013. Since startup, over 16 million gallons (> 30,000 bed volumes) have been treated with an average removal of around 75% for suspended copper and 60% for dissolved copper. Backwash is required at about 4000 bed volumes, but with a combination of air sparging and high flow backwash, the suspended material appears to be effectively removed from the bed.
The APTsorb™ media produced equivalent copper removal to the existing treatment system components of the bag and cartridge filters, the break tank, the carbon tank and the first commercial ion exchange tank. By reducing the size and complexity of the system, the capital and operation and maintenance costs are substantially reduced. Based on the existing data, using a single APTsorb™ tank will reduce annual operating costs by about a factor of 6; from around $130,000 to $21,000.
To see and hear the presentation on the Soudan Project go to:
- Presentation Date July 30, 2014
- Event 30th Annual Meeting of the American Society of Mining and Reclamation
- Venue Oklahoma City, Oklahoma
- Presenter(s) Eger, P, Jones, P, Green, D