Firebricks are made by flint clay clinker and binder,through Crushing,Mixing,Shaping,Drying and high temperature Sintering.
Al2O3 content is 30%-48%,SiO2 content is 50%-65%,and a small number of alkali metals,alkaline earthmetal oxides TiO2,Fe2O3 etc.
Mineral composition is usually mullite, quartz and glass phase.