Emerging direct lead smelting processes offer advantages over blast furnace smelting, such as elimination of the sintering step and the need for coke, utilization of the exothermic heat of the oxidation reactions during smelting, potential use of pure oxygen, and production of a so2-rich gas. However, the new processes require additional stages, and a high-pbo slag must be produced to obtain a low-s bullion. This project aims to optimize conditions for producing low-s bullion and a throwaway slag from clean typical Missouri lead concentrate in a single reactor by combining experimental studies with computer simulations. The "submerges smelting" technique was adopted, along with calcium ferrite slags, in which lead is only one-tenth as soluble as in silicate slags. Computer simulations use stepsol, the umr version of the solgasmix program. A thermochemical model for the pb-s-o system was developed and will be adjusted to agree with experimental data for the pure system. The model will be further modified to simulate smelting results and identify process variable that optimize the single-step direct lead smelting process using a typical Missouri lead concentrate. The model will be extended to multistep or countercurrent processes such as kivcet and qsl for comparison with the optimized single-step process.