Abstract: The sorbent capacity of calcium oxide with respect to sulfur dioxide is increased by calcining limestone or dolomite in an atmosphere where the partial pressure of carbon dioxide is greater than 40 percent of the equilibrium partial pressure of carbon dioxide over calcium carbonate at the reaction temperature. Where dolomite is the starting material, it may be calcined in a two-step heating process in which the atmosphere during the first heating stage contains carbon dioxide and the temperature is maintained in the dissociation range of magnesium carbonate (M.sub.g CO.sub.3); the atmosphere of the second heating stage also contains carbon dioxide, but the temperature is maintained in the calcium carbonate (CaCO.sub.3) dissociation range. Calcium oxide so produced in such an atmosphere of carbon dioxide sufficient to delay calcination is found to have relatively large mouthed pores capable of sorbing increased amounts of sulfur.

Abstract: The disclosed process provides for the production of a desulfurized fuel gas from a sulfur-containing fuel oil by absorption, in a first reaction zone, of the sulfur contaminants with a calcium oxide-containing material, which material is then further treated to render it environmentally stable without producing a sulfur-rich gas process stream. The spent limestone from the oil gasifier is reacted with an oxygen-containing gas in a second reaction zone for conversion of the calcium sulfide to calcium sulfate and the sulfated material is then transferred to a third reaction zone wherein it is reacted with carbon dioxide for conversion of the calcium oxide to calcium carbonate.