IMPROVEMENT OF MODELING ON THE PIDGEON PROCESS FOR MAGNESIUM PRODUCTION BY INTRODUCING THE VARIABLE THERMOPHYSICAL PROPERTIES

The variable thermophysical properties were introduced into the coupling model of heat transfer and reduction reaction in the Pidgeon process to improve the accuracy of the numerical calculation. The distribution of temperature and magnesium reduction extent in the briquette layer, and the total magnesium reduction extent in the retort were investigated. The model results show better agreement with those of industrial production. The feature of 'layer shift' in the briquette layer during the reduction process was clearly shown. It was shown that the reduction reaction occurs only at a thin interface. The slag layer with lower thermal conductivity of 0.4 W.m-1.K-1 formed during reduction strongly hinders the reaction to move forward within the layers, resulting in the slow magnesium production rate in the Pidgeon process. The improved model can provide a more accurate quantitative prediction for magnesium reduction in the Pidgeon process, which is important for key equipment innovation and the development of new magnesium production techniques.