An electrofusion (EF) process is also used to synthesize spinel. Starting materials
such as natural magnesite and calcined alumina are melted in an electric arc furnace
to a temperature above the melting point of the mixture, so that MgO and
Al2O3 react with each other to form spinel in the molten state. After reaction,
the molten product is cooled to a solidified ingot that can be crushed to aggregates