Peculiarities of protective layer formation in fireclay-based castables during potassium attack

Abstract

The potassium released in biomass boilers (used for wood incineration) during fuel burning and penetrates deep into the fireclay-based castable, forming new corrosion compounds (kalsilite, leucite, etc.). The volume of new compounds increases and causes degradation of fireclay-based castables. In addition, the thermal expansion coefficient of altered zones becomes significantly different from that of the original zone in a refractory promoting stress and later degradation of material. However, it was found that dispersive quartz additive retards corrosion process, due to formation of high viscosity amorphous layer.