Cement expansion agent - based on calcia,alumina,sulphate and fluoride fused in a resistance furnace

摘要

A mixture of bauxite, gypsum and cryolite to give a CaO/Al2O3 ratio of 0.5-20 and a CaSO4 content of 30-80 wt.% and a fluoride content of 0.2-20 wt.% is melted in 20-400 v. A.C. resistance oven with a current density of 0.8-8.0 amp/cm2. The melt is either allowed to cool insulated or cooled by water spray or air jets.