Conversion of Moroccan phosphogypsum waste into nano-calcium fluoride and sodium hydrogen sulfate monohydrate

The phosphoric acid production in the world generates a large amount of phosphogypsum with the emission of toxic acid fluorine gas into the atmosphere, which forms a significant source of environmental contamination. In this work, a novel and a simple procedure allows converting phosphogypsum waste by using hydrofluoric acid and sodium fluoride into valuable products. The obtained results confirm well the efficiency of this procedure, which permits to synthesize at room temperature, the sodium hydrogen sulfate monohydrate and a relatively pure nano-calcium fluoride from the exact stoichiometric proportions of the phosphogypsum, hydrofluoric acid, and sodium fluoride. The total phosphogypsum conversion is achieved after reaction time equal to 1.5 h. Generally, this procedure offers not only a solution for reducing phosphogypsum waste but also permits to obtain valuable products, which interest several sectors of industry.