PHASE-EQUILIBRIUM, MICROSTRUCTURE AND PROPERTIES OF SOME MAGNESITE-CHROMITE REFRACTORIES

The effect of phase equilibrium and microstructure of magnesite-chromi te batches containing from 0 to 100% Egyptian chrome ore, with interva ls of 10%, on their physical properties was studied. The phase equilib rium data were calculated using the phase relationships within the sys tem M-M(2)S-CMS-MR (M = MgO, S = SiO2, C = CaO, R = R(2)O(3)) A comput erized electron-probe microanalyser was applied to study the microstru cture as well as microchemistry of the fired magnesite-chromite co-cli nkers. Some physical and technological properties of the co-clinkered briquettes were also investigated by determining densification paramet ers, spalling resistance and load-bearing capacity. It is concluded th at dense, spalling resistant and refractory magnesite, magnesite-chrom e and chrome-magnesite refractories could be produced by co-clinkering of magnesite-chromite batches of 100:0, 70:30 and 30:70 weight ratios , respectively, at 1600 degrees C. The prepared co-clinkers were subse quently graded, moulded and refired up to 1700 degrees C in order to o btain direct-bonded bricks. Meanwhile, dense chromite refractories wit h lower refractory quality could be processed by firing the Egyptian c hrome ore up to 1600 degrees C.