Tadashi Kuwayama*, Atsuhiro Honda**, Masaru Yamada** and Tadashi Mise*

(*Daido Inst. of Tech, **Osaka City University)

Abstract

Electric furnace slags are classified into two groups; each is produced during the process of extracting the impurities from molten steel and controling the quality of steel, one by oxidizing, the other by reducing. Reducing slag has the two styles, one is powdered and the other is blocked. Powdered reducing slag has hardening properties by hydration, however, their properties are dependent by the steel making condition. In this study, the hardening properties and the promotion of this properties for reducing slags produced by different steel making plants were observed. It has been seen that the hardening properties of reducing slag are caused by the hydrates created from 12CaO . 7Al2O3 that is the one of the crystals constituting redusing slag and mixing gypsum (CaSO4 . 2H2O) have promoted largely the hadening properties of reducing slag by created hydrate (3CaO . Al2O3 . 3CaSO4 . 32H2O) from 12CaO . 7Al2O3 and CaSO4 . 2H2O. By mixing of the industrial solid waste containing CaSO4 . 2H2O, the hardening properties of reducing slag were promoted largely likewise mixing CaSO4 . 2H2O only.

Key words: reducing slag, hardening propering, utilization of solid waste, crystal structure