Water pollution potential of spent oil shale residues

Physical properties, including porosity, permeability, particle size distribution, and density of spent shale from three different retorting operations, have been determined. Slurry experiments were conducted on each of the spent shales and the slurry analyzed for leachable dissolved solids. The concentrations of the various ionic species in the initial leachate from the column were high. The major constituents, SO₄ and Na, were present in concentrations of 90,000 and 35,000 mg/l in the initial leachate; however the succeeding concentrations dropped markedly during the course of the experiment. A computer program was utilized to predict equilibrium concentrations in the leachate from the column. The extent of leaching and erosion of spent shale, and the composition and concentration of natural drainage from spent shale has been determined using oil shale residue and simulated rainfall. Concentrations in the runoff from spent shale have been correlated with runoff from the spent shale have been correlated with runoff rate, precipitation intensity, flow depth, application time, slope, and water temperature.