Laboratory Simulation of Fly Ash as an Amendment to Pyrite‐Rich Tailings

Abstract

AbstractColumn leaching experiments show that fly ash Interlayered with sulfide‐rich tailings can reduce the vertical permeability of tailings by at least three orders of magnitude. Chemical reactions between the fluid, alkaline fly ash from Western coal and pyritic tailings result in a one to three order of magnitude reduction in the dissolved metals content of the effluent solution. Metal precipitation, which produces the dissolved metals reduction, is a significant element in the permeability reduction. The combined factors reduce the metals flux from the tailings by four to six orders of magnitude. We believe that tailings ponds with fly ash layers as amendments can greatiy reduce ground water contamination from pyritic tailings. In addition, concentrated application of fly ash layers near the end of mining should act to restrict infiltration and access of oxygen, thereby enhancing reclamation. Similar results maybe obtainable using other amendments with lower base capacity (lime, crushed limestone, trona).