Reaction mechanisms of blast furnace slag in liquid and vapor dominated hydrothermal systems

Abstract

In order to develop an efficient process for the treatment of waste slag, the behavior of hydrothermal reaction of blast furnace slag has been investigated. For blast furnace slag, an experiment was conducted under various hydrothermal conditions with a liquid and vapor phase in the presence of saturated water steam pressure using an autoclave. The results indicated that calcium silicate hydrate (C-S-H) and tobermorite (Ca5Si 6O16(OH)2 · 4H2O) were the major phases formed in the treated samples. It was also confirmed that the hydrothermal reaction process was strongly affected by the hydrothermal conditions. In particular, the hydrothermal reaction proceeded more rapidly in vapor phase than in liquid one. Accordingly, the reaction mechanism of the hydrothermal treatment of blast furnace slag has been clarified. © 2007 ISIJ.