2015-02 - Getting the Lead out (and other Trace Metals). Solving Mine Water Problems with Peat-based Sorption Media.
To be presented at
the 2015 National Meeting of the Society of Mining Engineering
February 2015, Denver, Colorado
Paul Eger, Global Minerals Engineering LLC, Hibbing, MN
Peggy Jones, Doug Green, American Peat Technology, Aitkin, MN
Pilot tests were run at two mines using peat-based sorption media to remove Pb, Zn and Cd. The first pilot was designed to model active (pressurized tank) and passive (biocell) approaches; the second contained only a pressurized tank.
At the first site, pH was greater than 7 and contained 1500 ug/l Pb, 100 ug/l Zn and 1.5 ug/l Cd. Both pilots removed over 99% of the lead and reduced all metals to below permit values. The biocell operated for about 9 months and met the permit limit of 11ug/l for 15000bv (bed volumes). When the pilot ended over 25,000 bv had been treated and Pb removal was still over 80%.
At the second site pH was also above 7 but zinc was the major parameter of concern. Input concentrations were 465 ug/l Zn, 135 ug/l Pb and 1.9 ug/l Cd. The peat media effectively removed Zn but after 4500 bed volumes the concentration exceeded the permit limit of 160 ug/l. An additional tank of media was installed and successfully reduced all metals to below permit limits; extending the lifetime of the initial tank to over 12,000 bv.
Treatment costs ranged from 43 to 90 cents per 1000 gallons; capital costs were less than 50% of a standard chemical treatment plant.