A cost-effective approach to recycle serpentine tailings:Destruction of stable layered structure and solvent displacement crystallization

摘要

In this work,the stable layer structure of serpentine,which seriously restricts the extraction of magnesium,was broken down,and a nearly 94%leaching efficiency of Mg was obtained by adding 5%fluorite powder.Compared with the system without fluorite,the Mg leaching efficiency increased by 36.42%.This result was achieved because the complexation of fluorinion(F
)with Si in serpentine promoted a distorted tetrahedral orientation,which led to a loose crystal structure of serpentine and contributed to exposing more Mg for a remarkable increase in Mg recovery.It is suggested that fluorite powder could replace expensive assisted reagents in the leaching process,which would markedly decreased the cost.Moreover,an energy-efficient‘‘solvent displacement crystallization”(SDC)method was employed to efficiently recover magnesium(99.04%)from pregnant solutions.At the same time,the reuse of fluorinecontaining solutions was explored.