Preparation and performance analysis of gas-quenched steel slag beads

Abstract

The low utilization rate of steel slag in China has exposed serious environmental and social problems. In the present work, the basic oxygen furnace (BOF) slag was modified by blast furnace (BF) slag and then beaded by the means of gas quenching. The gas-quenching rate, bead formation rate, physical properties, microscopic characteristics and free lime (f-CaO) of gas-quenched slag beads were analyzed to broaden the utilization of BOF slag. The results show that the more BF slag is added, the higher the gas-quenching rate is, and the lower the bead formation rate becomes. When no BF slag is added, the beads are mainly composed of magnetite, limonite and melilite. After BF slag is added, a large amount of glass phase and a little amount of Ca2SiO4 and MgO are found in beads. The content of f-CaO beads decreases after the modified slag is gas quenched at high temperature. Moreover, the more BF slag is added, the higher the elimination rate of f-CaO becomes. Considering the industry standard of steel slag sand in China as well as the gas-quenching rate, physical and chemical properties, the gas-quenched steel slag beads with 5 and 15% BF slag better meet the medium sand standard, which can be used as fine aggregate.