Agglomeration of magnesia powders precipitated from sea water and its effects on uniaxial compaction

The effect of calcination temperature on uniaxial compaction of magnesium oxide (MgO) powders precipitated from sea water was examined. The calcination at a temperature between 900 and 1200 °C had a great influence on the compressibility of the powder and green density. Before the compaction operation, the calcined powders were ball-milled for 1.5 h. The relationship between green density obtained by uniaxial compaction and applied pressure between 50 and 200 MPa was analyzed by Nieszʹs equation. The agglomerate strength increased with calcination temperature. The plots of relative density versus logarithmic pressure also exhibited a break point, indicating the pressure at which the contact points in porous agglomerates started to be destroyed. Likewise, the agglomeration state of the MgO powder appeared to be remarkably affected the compressibility and green density. The changes in agglomeration states of calcined powder were observed using scanning electron microscope (SEM).