Experimental measurements and mathematical model predictions for flash combustion of copper sulfide particles in a turbulent gas jet are described. A mathematical model has been developed to describe the process taking place in an axisymmetric flash-furnace shaft. The model incorporates turbulent fluid dynamics, chemical reaction kinetics, and heat and mass transfer. The key features include the use of the k-ε turbulence model, incorporating the effect of particles on turbulence, and the four flux-model for radiative heat transfer. The experiments were carried out in a laboratory flash furnace. Gas temperature, sulfur content in the particles, SO₂ concentration in the gas phase, and particle dispersion during flash-smelting at different locations were measured for various matte grades. Reasonable agreement was obtained between the measured and predicted values. The predicted results are compared with experimental data obtained from Outokumpu pilot and comercial flash furnaces. Satisfactory agreement is obtained between the predicted and measured data in terms of the gas-phase tem-perature and the SO₂ and O₂ concentrations along the centerline. The model predictions show that the reaction of sul-fide particles is almost completed in the upper zone of the furnace within about 1m of the burner and the double-entry burner system with radial feeding of the concentrate-laden distribution air gives better performance than the single-entry burner system.