The prospect of oil shales as an alternative means of hydrocarbon production has sparked concerns as to the chemical composition of the original shale as well as that of the spent shale, oil, water, and gas fractions produced due to retorting. This study is concerned with a chemical concentration comparison between raw and spent shales from Lewis County, Kentucky. Eighteen elements (Si, Ti, Al, Fe, Mg, Ca, Na, K, P, Ba, Co, Cr, Cu, Mo, Ni, Pb, V, and Zn) were investigated in two shale lithologies: the Sunbury and Cleveland Shales. Three slightly different modified Fischer Assay procedures were compared for their effects on the resulting spent shale chemistry. Two procedures employed sweep gases (nitrogen and steam), while the third used no gas sweep. The heating rates dur ng the procedure were also varied.

It was found that the employment of a sweep gas throughout the retorting procedure induces a measurable degree of depletion over a no gas sweep procedure. The gas flow enhances the effectiveness of pyrolysis, and aids in the formation of aerosols in which elements are carried out of the retort to be condensed in the oil and water fractions.

It was also found that differences in original shale mineralogy (e.g., elemental substitutions in major minerals and trace mineral compositions) was responsible for differential elemental depletions seen in the two lithologies.

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