In the partial oxidation of a sulfur- and metal-containing carbonaceous charge fuel to produce a sulfur-containing synthesis gas and metal-containing molten slag, an integrated method of charge fuel pretreatment and Claus unit tail gas sulfur removal is provided. The process of the instant invention is advantageous over other partial oxidation processes in that: (i) a fluid, molten slag which flows easily is produced, thereby improving reactor performance; and (ii) the overall removal of sulfur compounds from the synthesis gas is made simpler, more efficient, and less costly, as the need for a conventional Claus unit tail gas sulfur removal process is eliminated.