Total Model with Zinc and Iron Reduction Kinetics for Simulation of a Coke Packed Bed Furnace

A new mathematical model of the smelting reduction process with coke packed bed has been developed for recycling the dust containing zinc oxide. Kinetic experiments of the zinc reduction were carried out in the temperature range between 1643 and 1823K in order to determine the rate constants and activation energy. It is observed that zinc is reduced faster for slag containing iron. The rate constant of zinc reduction by iron oxide was determined. The mathematical model of zinc reduction is composed of one-dimensional flows of solid, liquid and gas phases. It is formulated in terms of heat and mass balances in the furnace, coupled with reduction kinetics of iron/zinc oxides and heat transfer among the components. Operation conditions of pilot plant tests with a scale of 10 tons per day are simulated with the model. It is found that the temperature and CO2/CO ratio of gas at the furnace top must be controlled by the post combustion to prevent zinc accretion. The operation results of the pilot plant are compared with those of the simulation ones. It is confirmed that zinc and iron oxide is reduced between two stage-tuyeres and that zinc accretion at the wall of furnace top is decreased by the post combustion.