Analysis and experiment of sintering and densification of magnesia particles

Abstract

Magnesia densification is essential for Mg-based refractories and materials to attain better thermal performance and longer service life. Few industrial-scale processes can produce magnesia with the required bulk density of above 3.40 g/cm3 (or relative density of over 95 %) from natural magnesites. The inability to achieve the desired densification is related to the low heat transfer between gas and solids inherent in large-sized greenbodies typically sintered in industrial shaft kilns. This study proposes sintering particles of 0–6 mm in primary sizes corresponding to those employed in most refractory end-products of sintered magnesia. Microstructures of the sintered particles are analyzed, and the underlying sintering mechanisms are discussed. The sintering of small particles can achieve over 95 % of densification at 1300–1600 °C for less than 10 min. This study provides an alternative approach to producing high-density magnesia with the potential for substantial reductions in energy consumption and carbon emissions.