Reduction of phosphogypsum to calcium sulfide (CaS) using metallic iron in a hydrochloric acid medium

Our study aims to decompose phosphogypsum (PG), mainly composed of CaSO4.2H2O, by reduction in an acidic medium. We evaluated the decomposition PG various reaction mechanisms. Sulfate ions from acid digestion are reduced sulfide hydrogen gas produced solution hydrochloric attack metal iron. The solid residues obtained have been determined and monitored X-Ray Diffraction, Fourier-Transform Infrared spectroscopy Ultraviolet-visible spectroscopy. microstructure was observed scanning electron microscope (SEM). results show that formed iron reduces sulfur S(VI) S(-II). insoluble water, gives a residue containing CaS, which is only sparingly soluble water. also contains anhydrite, bassanite ferrous chloride. monitoring quantities under varying experimental conditions (temperature, time, mass volume on PG) HCl showed amounts less than 32% mass. When added increases, decreases sharply. stabilizes at 10% when higher required