Mathematical modeling of chalcopyrite concentrate combustion in an axisymmetric flash-furnace shaft

A mathematical model has been developed to describe the combustion of chalcopyrite particles in an axisymmetric flash-furnace shaft. The model incorporates turbulent fluid dynamics, chemical reaction kinetics, and heat and mass transfer.; Numerical computations have been performed for the turbulent recirculating flow field of a gas jet in a confined cylindrical system. The effects of inlet conditions and various correlations for the dissipation rate of turbulent kinetic energy at the inlet have been tested. A new correlation equation for the latter yielding the best results was obtained.; In order to predict the behavior of a particle-laden gas jet under flash-smelting conditions, model predictions have been obtained for various inlet conditions, feeding modes of the primary (or distribution) gas stream at the inlet, particle sizes, degrees of particle loading and values of oxygen enrichment. The particle phase is treated in the Lagrangian framework, and the drag and the gravitational forces acting on the particle are included. Agreement of the predicted results with experimental data taken from the literature is satisfactory. In the case of axial feeding of particles, the presence of solid particles causes the gas-phase axial velocity to be greater near the centerline and less in the outer region than in a single-phase gas jet. More uniform distribution of particles is obtained by radially feeding the distribution air.; Finally, model predictions have been performed for the flash-smelting furnace system. The predicted results are compared with experimental data obtained from an Outokumpu pilot flash furnace. Satisfactory agreement is obtained between the predicted and measured data in terms of the gas-phase temperature and the SO{dollar}sb2{dollar} and O{dollar}sb2{dollar} concentrations along the centerline. The model predictions show that the reaction of sulfide particles is almost completed in the upper zone of the furnace within about 1 m 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. The predicted results also show that the radiation from the furnace walls and between the particles and the surroundings is the dominant mode of heat transfer in the flash-smelting furnace.