A cost-effective approach to recycle serpentine tailings: Destruction of stable layered structure and solvent displacement crystallization
Wengang Liu, Wengang Liu, Xiangyu Peng, Wenbao Liu, Wenbao Liu, Naixu Zhang, Xinyang Wang
Abstract
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 fluorine-containing solutions was explored.