Leach Potential of Processed Shale as Determined by Two Extraction Methods

摘要

Batch leach tests were performed on 12 samples of Green River Formation spent oil shales generated from four retorting processes. Two standard leaching procedures were used, ASTM (American Standard Testing and Materials) method D3987 and EPA/RCRA (Environmental Protection Agency/Resource Conservation and Recovery Act) extraction procedure. The trace elements arsenic, boron, cadmium, chromium, molybdenum, lead, and selenium were of interest, as were sulfate and chloride anions. The different leaching media used in the ASTM and EPA methods appear to account for the major differences in the leachates extracted from identical oil shale wastes. The EPA extraction medium is acidic (.1N acetic acid solution) and, thus, is capable of mobilizing significantly more arsenic, cadmium, chromium, lead, and selenium from processed oil shale. Molybdenum, however, becomes more mobile at greater pH values. The amount of boron in leachates appears to be dependent on the temperature at which the oil shale is retorted. The anions SO sub 42- and Cl sup - in processed oil shale leachates are influenced most by retorting atmosphere and leaching time, respectively. According to RCRA guidelines the concentrations of arsenic, cadmium, chromium, lead, and selenium in the leachates of all the processed oil shale studied are considered nonhazardous. 31 refs., 15 figs., 10 tabs. (ERA citation 12:024603)