Raw magnesite is used directly for making some of the end products like chemicals and
synthetic rubber. In one use, namely fused magnesite refractory, it is used in fused form. But
in most of the end-uses, magnesite is used in one of the two main intermediate products
namely, caustic magnesia and dead-burnt magnesite or DBM. In all these three intermediate
products, magnesite is the raw material, and its specifications are discussed as follows.
1. Caustic magnesia: Caustic Magnesia (low-calcined magnesite) is obtained by
calcining raw magnesite in a shaft or rotary kiln between 800-10000C. However, after
manufacturing, the caustic magnesia is generally not subjected to high temperatures during its
2. DBM: Unlike caustic magnesia, DBM is used only in one class of products namely,
refractory. DBM as a refractory is subjected to not only high temperature of over 15500C, but
also repeated heating and cooling (thermal shocks).
3. Fused magnesia: Fused magnesia is very costly and used in very special cases. The
industries specify practically pure magnesite containing above 99% MgO and only nil to trace
impurities. In this case, no binder is required and hence there is no need of even a minimum
amount of Fe2O3 unlike in the case of DBM.