Mechanism of slag pellets sticking on the wall of reduction pot in magnesium production by Pidgeon process

In the preparation of magnesium by Pidgeon process, the phenomenon slag pellets sticking on the wall of reduction pot always appear, and the glaze sticking on the inner wall of the reduction pot is difficult to remove. The mechanism of this phenomenon is studied in this work by X-ray fluorescence spectrometer (XRF) measurement, electron probe microanalyzer scanning (EPMA) analysis, differential scanning calorimetry (DSC) analysis, and thermodynamic calculations. The main components of the glaze are MgO, Ca₁₂Al₁₄F₂O₃₂, CaF₂, CaO, and a small amount of Ca₄Si₂O₇F₂. The solid-liquid transition temperature of Ca₁₂Al₁₄F₂O₃₂ and CaF₂ is close to the production temperature of Pidgeon process, which leads to the bonding between the slag pellets and the pot wall. The loss of CaF₂ in glaze layer will reduce the total amount of liquid phase and increase the temperature at which Ca₁₂Al₁₄F₂O₃₂ is completely transformed into liquid phase, which causes glaze layer sticking on the inner wall of the reduction pot.