353 / 2024-03-18 15:02:41

Sequence closed-loop recovery of fluoride, phosphate, and sulfate anions from phosphogypsum leachate via precipitation-electrodialysis-crystallization approaches

phosphogypsum,leachate,Recovery,fluoride,phosphate,sulfate

6、能源资源清洁加工与转化利用 > 8、固废资源综合利用

Phosphogypsum (PG) is a large-scale industrial by-product generated during the production of phosphoric acid, typically being deposited in landfills worldwide. The leaching of fluoride (F^–), phosphate (PO₄^3–), and sulfate (SO₄^2–) anions from PG into water bodies through rainfall results in significant environmental pollution. Herein, we proposed a stepwise precipitation combined with electrodialysis and crystallization strategy for efficient recovery and valorization of multiple anions from PG leachate. Our method demonstrates effectiveness both theoretically and practically. Consequently, fluoride anions were precipitated as CaF₂ and Ca₅(PO₄)₃F at pH 4.7, with a recovery rate of 98.80%; phosphate anions as MgNH₄PO₄·H₂O at pH 8.5, with a recovery rate of 99.91%; and sulfate anions through electrodialysis and crystallization with a recovery rate of 99.89%, ensuring effluent met discharge standards. In addition, the concentrated sulfate-rich solution was employed for electrochemical production of persulfate, yielding ammonium persulfate salts after cooling crystallization. Our integrated approach for multiple anions recovery from PG leachate offers significant environmental and economic benefits, providing valuable insights and references for future research and practical productions.