Effect of crystal size on dolomite decrepitation in glass furnaces

Crushed dolomite is widely used in the manufacture of soda-lime-silica glass. Upon introduction into furnaces, particles of dolomite may decrepitate with deleterious results for both the furnace operation and glass quality. It is widely assumed that volatile matter within the dolomite is responsible for its decrepitation, but there is no direct evidence to support this and so another factor must be at work. Accordingly, the present study was undertaken to seek correlations between decrepitation and the physical and chemical properties of a suite of dolomite samples. It was found that the degree of decrepitation increases with the size of the crystals within dolomite particles. It is hypothesised that particles with larger crystals have longer pre-existing flaws along the crystal boundaries and also have fewer crystal boundaries to retard the propagation of fractures. Explosive fracturing along these flaws is initiated by the rapid heat induced expansion of dolomite particles in furnaces.