A green method for selective crystallization and extraction of suanite (Mg2B2O5) crystals from boron bearing slag under super-gravity

A green method was proposed for selective crystallization and extraction of suanite crystals from boron bearing slag for ceramics reinforced phase under super-gravity. Through investigating crystallization behavior of boron bearing slag melt, olivine (Mg2SiO4) and suanite (Mg2B2O5) crystals were precipitated successively at various temperature ranges of 1623-1473 K and 1473-1323 K. Hence, selective crystallization conditions for the last precipitated suanitie crystals were investigated and two-step separation of suanite crystals from boron bearing slag was conducted in a super-gravity field. Firstly, the mixture of suanite and olivine crystals was separated from slag melt at crystallization temperature of suanite. Subsequently, the molten suanite phase was separated further from olivine crystals at melting temperature of suanite, which precipitated further into suanite crystals after cooling process. Accordingly, high-purity suanite crystals were efficiently attained from boron bearing slag, providing an essential ceramics reinforced phase for ceramic-metallic composite material and glass ceramic.