17. Fire Resistance of Kaolin

17. Fire Resistance of Kaolin

Fire resistance refers to the ability of kaolin to resist high temperature and non-melting. When softening occurs at high temperature and melting begins, the temperature is called refractoriness. It can be directly measured by standard temperature cone or high temperature microscopy. It can also be calculated by M. A. Beezbelodov's empirical formula.

Refractoriness t(?) =[360+Al2O3-R2O]/0.228

Formula: Al2O3 is the mass percentage of Al2O3 when the sum of SiO2 and Al2O3 analysis results is 100; R2O is the mass percentage of other oxides when the sum of SiO2 and Al2O3 analysis results is 100.

The error of calculating refractoriness by this formula is less than 50 C.

The refractoriness is related to the chemical composition of kaolin. The refractoriness of pure kaolin is generally about 1700C. When the content of hydromica and feldspar is high and the content of potassium, sodium and iron is high, the refractoriness of kaolin decreases. The lowest refractoriness of kaolin is not less than 1500 C. The industrial department stipulates that the R2O content of refractories is less than 1.5-2% and that of Fe2O3 is less than 3% .