REVEGETATION OF COARSE TACONITE IRON-ORE TAILING USING MUNICIPAL SOLID-WASTE COMPOST

On Minnesota's Mesabi Iron Range, coarse taconite iron ore tailing is often used as the principal material in the construction of dams for l arge tailing impoundments. Mineland reclamation rules in Minnesota req uire that tailing dams be vegetated to control erosion for dam stabili ty and safety. Coarse taconite iron ore tailing is characterized chemi cally by an alkaline pH, low organic matter content, lack of plant-ess ential nutrients, and low cation exchange capacity; physically by its coarse texture, lack of structure, low water-holding capacity, and dar k color; and biologically by a lack of microorganisms. To investigate the potential of composted municipal solid waste to ameliorate these c onditions and make the material more amenable to plant establishment a nd growth, the US Bureau of Mines implemented a series of factorial ex periments at two active taconite mine sites in northeastern Minnesota. At each experimental site, vegetative cover has improved depending on the type of municipal solid waste compost used and rate of applicatio n. At site I, overall plant cover across all treatments has improved f rom zero prior to experimental manipulation to 72% after four years, w ith seven treatment combinations exceeding 90% cover. At site II, over all plant cover has improved from zero prior to experimental manipulat ion to 83% after four years, with 23 treatment combinations exceeding 90% cover. At both sites, total cover has progressively increased over four years and has not reached steady-state conditions. These results suggest a possible new strategy for reclaiming difficult sites throug h the use of municipal solid waste compost.