Investigation of parameters affecting grain growth of sintered magnesite refractories

The parameters influencing grain size of sintered magnesite such as temperature (1700 and 1800 °C), time (19 and 50 min), cooling rate (5, 10 and 25 °C min−1) and various particle size (−3; +3,−5; +5,−8; +8,−10 mm) were investigated using different sintering regimes to improve grain growth. The effects of impurities (i.e. SiO2, CaO, Fe2O3, and CaO/SiO2 ratio) on grain growth were also evaluated by EDX analysis for each sample based on the variation of particle size, cooling rate and the change in the colour of samples (dark–light). For the samples sintered at 1700 °C, the decrease in the cooling rate from 10 to 5 °C min−1 and the increase in the dwell time from 19 to 50 min enhanced grain size significantly. The rise in sintering temperature to 1800 °C for 19 min, using cooling rate of 25 °C min−1, resulted in maximum grain growth (~140 μm) for +3,−5 mm particle size of dark-coloured samples.