Numerical Simulation Of Lead KIVCET Smelting Process

ABSTRACT:The increasingly strict requirement on environmental protection lead accelerated technical progresses in the lead smelting industries in China. As an alternative, some enterprises started to introduce and use new foreign direct lead smelting technologies, and the Kivcet process is one of the most prominent results. In this paper a multi-field coupling simulation was carried out with the commercial CFD software Fluent6.3according to designed structure of Kivcet furnace and smelting process features. Through the simulation study of the lead smelting process, the distributions of the flow field, temperature field and concentration field as well as the particle trajectories inside the furnace are analysed in detail, so as to provide technical guidance for the construction and operation of the KIVCET furnace. The main work and conclusions are summarized as follows.(1) A physical model was established based on the designed structureof the Kivcet furnace and a numerical model was developed to investigate the transfer processes and reactions between the gas and particle (industrial oxygen-lead concentrate) phase in the lead smelting process,. In particular, a surface reaction model was adopted to simulate the coke reduction reaction in filter layer of the bath surface.. An industrial test was also carried out and the result manifests that the simulation model is reliable and can accurately reflect the relevant field distribution inside the Kivcet furnace.(2) The coupling simulation for the standard lead direct smelting process was performed based on the operation conditions with four nozzles being adopted for the production. The results reveal that the industrial oxygen forms a cylindrical high-speed air column in the center of the furnace after entering the reaction shaft through the concentrate nozzles. Moreover, the reactions inside the furnace mainly exists within the region of1meter under the nozzles, and the high temperature zone located at the region which is2meters under the nozzles. In addition, the gas flow has an significant influence on the concentrate particles, and about10percentage of the particles will be carried away by the flue and become the dusts.(3) Basisdes the standard case, the effect of the coke diameter on the lead smelting process was studied. The results indicates that small coke particles tend to burn completely in the reaction shaft, thus little will fall into the bath to form the coke filter layer.(4) Simulations were also carried out for cases with different nozzle operation programs (i.e. the standard case with four working nozzles, three nozzles in operation and two nozzles in operation) to study the feature of the gas-particle mixing and reaction processes. The results show that the main gas columns below the four nozzles restrict each other, thus a small shift of the gas column and the weak reflux are found in the standard case(the case when four nozzles are in use). When three nozzles are put in use, the turbulence exists among the three gas columns, and the reflux is stronger below the nozzle that is not in service. Moreover, when only two nozzles are in operation, the turbulence of the high speed gas stream below the two wording nozzles is weak, whereas the reflux occupied the whole shaft is dramatically strong.