Crystallisation behaviour and enhanced separation of RE-phase in RE-bearing blast furnace slag

Abstract

With the wide application and consumption of rare earths (REs), the secondary resources of RE-bearing blast furnace slag are being investigated as viable resources for the recovery of these critical elements. In this study, the crystallisation behaviour including nucleation and growth kinetics of the RE-phase in RE-bearing blast furnace slag was studied and the optimal precipitation conditions for the RE-phase during the cooling process was obtained, providing an important reference and guidance for the efficient extraction and subsequent functionalised reuse of REs. Subsequently, the supergravity enhanced separation of RE-phase from the slag system was conducted in the optimal precipitation conditions of cooling rate (2 °C/min), experiment temperature (1200 °C), and holding time (100 min). At G = 1000, the RE-phase was successfully separated from molten slag, and the mass fraction of CeO2 in the separated sample increased from the original 20.51% to 74.85%, and the recovery ratio reached 92.06%. This indicated that the supergravity separation technology is considered to be an effective technology for the enrichment and recovery of REs from RE-bearing blast furnace slag.