Relationship of regional and local structures to Mount Pinatubo activity

In the production of a dense fused refractory, a dry gas is introduced into/onto a charge of refractory raw materials in a melting furnace. In particular, dry nitrogen gas is introduced through the bores of hollow electrodes used in an electric arc furnace. The resulting melt is poured into a mould where it is solidified or, alternatively, is allowed to cool in the furnace where it is solidified.