Preparation Of CaO-Al₂O₃-MgO-SiO₂Porous Slag Glass-ceramics

As one of the important auxiliary materials for iron and steel making, theindustry of ferroalloys witnesses a rapid advancement and increasing yield, leading tolarge quantity of ferroalloys slag, especially in China where the most iron is produced.The ferroalloys slag is worthy to be used because it comprises large amount of CaO,SiO2, Al2O3, MgO and so on. Therefore, casting away the ferroalloys slag means awaste of resource. More seriously, it can take up large area of land and pollute theenvironment.The present work focuses on recycling of the ferroalloys slag including waterquenched Si-Mn slag, water quenched C-Mn slag and retarded cooling Si-Mn slag.Basic properties, such as chemical and mineral composition, crystallization behavior ofthe ferroalloys slag were characterized and examined by chemical analysis, X-raydiffraction, scanning electron microscope and energy dispersive spectrometer.Moreover, the ferroalloys slag was used as the major raw material to prepare theCaO-Al2O3-MgO-SiO2slag glass-ceramics in the paper. The main conclusions are asfollows:1. The ferroalloys slag is low activity and acid slag which are mainly composedof SiO2, Al2O3, CaO, MgO and MnO. It should be noted that the water quenched slagis mainly composed of glass while the retarded cooling slag mainly consists ofminerals of pyroxene. The water quenched slag could make a good performance ofcrystallization after some heating treatment condition..2. The results show that taking the water quenched Si-Mn slag as major rawmat and adding small amount of quartz can produce the glass-ceramics withdiopside as maincrystal phase. Specifically, when the quartz addition is15%,the glass-ceramics has good ability of crystallization after heated by900℃×3h.3. Similarly, adding an appropriate of quartz into water quenched C-Mn slag, wecan produce the glass-ceramic with melilite as maincrystal phase. Moreover, theproduct also shows excellent ability of crystallization when the total amount of quartz is30%and heared by850℃×3h.4. Porous glass-ceramics with excellent performance can be manufactured withthe water quenched Si-Mn slag and floating beads. In addition, the optimum qualityratio of the two materials is3:7while the best heating treatment condition is900℃×60min+1125℃×40min.