Experimental investigation and three-dimensional computational fluid-dynamics modeling of the flash-converting furnace shaft: Part II. Formulation ofthree-dimensional computational fluid-dynamics model incorporating the particle-cloud description

A fluid-dynamics computer model of the flash-converting furnace shaft, whic h is based on basic principles, is presented. The model is fully three-dime nsional and incorporates the transport of momentum, heat, and mass and the reaction kinetics between the gas and particles in a particle-laden turbule nt gas jet. The k-epsilon model was used to describe gas-phase turbulence i n an Eulerian framework. The particle-cloud model was used to track the par ticle phase in a Lagrangian framework. The coupling of gas and particle equ ations was performed through the source terms in the Eulerian gas-phase gov erning equations. Copper matte particles were represented as Cu2S . yFeS(x) . Based on experimental observation, the oxidation products were assumed to be Cu2O, CuO, Fe3O4, and SO2. A reaction mechanism involving the external mass transfer of oxygen from the gas to the particle surface and diffusion of the oxygen through the successive layers of Cu2O-Fe3O4 and CuO-Fe3O4 was proposed. The predictions of the computer model were compared with the exp erimental data collected in a large laboratory furnace. Reasonable agreemen t between the model predictions and the measurements was obtained in terms of the fractional completion of the oxidation reactions and the sulfur rema ining in the reacted particles. The relevance of the computational model fo r further analysis and optimization of an industrial flash-converting opera tion is discussed.