"Many people have speculated on the possibilities for recovering the potential energy represented by the organic residue remaining in spent or retorted oil shale. A program of theoretical calculations was set up to examine the process considerations encountered with the burning operation. The combustion step necessary tor the release of this energy is identical, whether it be incorporated into a retorting procedure or considered separately as a means of producing byproduct waste heat. An engineering study has been made covering the burning of spent shales containing various amounts of organic residue. The purpose of this paper is to report the process considerations which were revealed by this analysis. Stoichiometric relationships were calculated, and the major equipment sized for various operating situations. No costs have been assigned; therefore economic considerations are not discussed. Certain general relationships, however, will be pointed out. Three alternative procedures have been examined: combustion with air, combustion with air plus heat recovery by recycled flue gas, and combustion with a mixture of air and recycle flue gas. Results are expressed in terms of the heat content of the hot-gas product issuing from the burning operation. The basis upon which the engineering calculations were advanced is reviewed in the following section."