The silica brick, one of the refractories made of SiO2, is used at coke ovens and hot blast stoves. For manufacturing silica bricks, conventionally, CaO has been added to quartz as a mineralizer. Our previous research suggested that adding K2O to quartz instead of CaO promoted the phase transition to tridymite even for the shorter heat treatment time and at the lower temperature. In the present research, the effect of the particle size of quartz on the phase transition behavior was investigated when using K2O as an additive. Five kinds of quartz with the average particle size of 1, 16, 39, 47, and 223 µm were prepared, and K2O was added. After firing these samples at 1300 ℃ for 5 h, crystalline phases were analyzed by powder X-ray diffraction. The results indicated that the amount of tridymite increased with the increase of the particle size of quartz and/or the K2O amount.

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