Crystallographic Characterization and Thermal Decomposition Behavior of High-Purity Microcrystalline Magnesite

摘要

As measured by SEM, the particle diameters of microcrystalline magnesite originating in Sichuan-Tibet distribute uniformity, most grains range in 2-4um . Three-dimensional (3D) crystal morphology assumes cubic or prismatic. The result of chemical analysis is similar to stoichiometric composition with little impurity and XRD indicates that the lattice constant is the same as macrocrystalline magnesite having standard d value and X-ray diffraction intensity. The decomposition temperature is 650℃ determined by DTA, which is also the same as macrocrystalline magnesite. Crystal morphology of nanometer periclase samples which are treated at 650 ℃ for 4hrs and calcined at 1000 ℃ respectively have been observed by FESEM, the former is<20nm and the latter is <200nm, both are rounded grains. The quality of high purity magnesite manufactured by high temperature shaft kiln is the same level as made in Japan and sea-water magnesite produced in the Netherlands, while the crystal size is slightly larger.