"This report provides a preliminary technical and economic evaluation of a novel process concept for the aboveground oil shale retorting technology. The original concept is that disclosed by A. E. Harcak in the U.S. Patent No. 4,340,463) assigned to the U.S. Department of Energy, Laramie Energy Technology Center. In brief description, the ""Use It All Retorting Process (UIARP) makes use of hot flue gas to pyrolyze pulverized raw oil shale in the entrained flow reactor. The flue gas is generated by burning spent shale together with coal in a slagging cyclonic combustor. The heat contained in the excess flue gas is recovered. From the technical standpoint , the concept appears quite feasible. The main focus of technical concern was centered on the slagging combustor, CIS burning of spent shale under slagging conditions has not been practiced commercially (with the possible exception of installations in Estonia, USSR). The closest commercial analog is found not in the power boiler field, as was originally stipulated, but in the flash-smelting of copper concentrates. Both the heat of combustion and inorganic fusible content are quite similar between the spent shale and copper concentrates . The success of the flash smelting technology (Outokumpu, Inco , Kivcet and Noranda gives rise to expectation that burning of the retorted shale under slagging conditions can be done on a commercial scale."