Thermodynamic study of magnesium (Mg) production by the Pidgeon process: The distribution of MgO and axial thermal field

Abstract

The magnesium slag of the Pidgeon process is rich in MgO, which restricts their resource utilization. In this paper, the MgO content in the magnesium slag at different positions of the reduction tank was analyzed and the heating model of the reduction furnace was established, which disclosed the distribution of MgO in the magnesium slag and the change of the axial thermal field of the reduction tank with time. Research shows that the content of MgO in the reduction tank firstly increased (from 0.20 m to 0.40 m), and then decreased, finally increased slowly (from 1.20 m to 2.40 m). The MgO content in the magnesium slag within 0.4 m away from the tank mouth is extremely high, which affects the resource utilization of magnesium slag. The MgO residual at different positions in the upper and lower reduction tanks are similar, indicating that the temperature in the reduction furnace is relatively stable. Temperature and heat transfer are the reasons for the uneven distribution of MgO at different positions in the reduction tank. The research results provide a theoretical basis for magnesium smelting and magnesium slag recycling.