Calcination of Slags for Electroslag Remelting

The hydrides in industrial lime, alumina, magnesia, and calcium fluoride were investigated through differential thermal analysis and X-ray diffraction, and their mass losses during heating up were studied by thermogravimetric analysis method. The results indicate that the industrial alumina, lime, and magnesia, which have more moisture or hydride and mainly include γ-Al2O3, Ca(OH)2, and Mg(OH)2, lose more mass during thermogravimetric analysis process. However, the mass of premelted slag consisting of lime, fluorite, alumina, and magnesia has almost no change, which means no hydride in it. Some relationships for calculating the mass loss were established according to the results of thermogravimetric analysis. These results will be in favor of setting up the rational calcination criterion for slag used in electroslag remelting process.