English

Abstract

Passive treatment system components containing limestone are an effective means to decrease Mn concentrations in coal mine drainage. As precipitates, sediment, vegetation, and other materials accumulate in the void spaces, permeability decreases and treatment effectiveness is reduced. Recently, the ability to recover manganese-bearing material for potential economic use while restoring treatment efficiency has been demonstrated at the De Sale Phase 2 passive treatment system, installed at an abandoned surface coal mine in western Pennsylvania. Efforts to date include pre- and post-recovery water monitoring; development of a unique full-scale recovery technique; preliminary physical, chemical, and mineralogical analysis; and identification of a potentially economically-viable use of the recovered material. The horizontal flow limestone bed was monitored 3, 24, 64, and 118 days after Mn recovery. Comparing the influent with the effluent indicated decreases in dissolved Mn concentrations from 64 to 30 mg/L, 55 to 10 mg/L, 46 to 9 mg/L, and 20 to 8 mg/L, respectively, essentially doubling treatment effectiveness. Over 40 cubic yards (30 cubic meters) of manganese-bearing material were recovered. Currently, the Mn material is being used by local ceramic artists as a glaze colorant and is being evaluated by other industries including brick manufacturing.