Elemental sulfur recovery from FGD gypsum and calcium cyclic utilization in coal-fired power plants

Flue gas desulfurization (FGD) gypsum mainly contains gypsum, which comes from the FGD by using lime or limestone. The effects of calcining temperature and time on calcium sulfide preparation were explored. The gypsum completely decomposed into calcium sulfide by calcining at 900 degrees C for 30 min. The effect of time on CaS and CO2 reaction were also explored in aqueous solution. The main phase was calcite phase after reaction 6 h, with nearly cubic particles and 1-2 mu m in diameter, which calcite can be reused in FGD process. Hydrogen sulfide was produced when CaS reacted with CO2. And then, irregular particle and pellets of elemental sulfur, with 0.5-5 mu m in diameter, were obtained by the H2S oxidation in Fe(III) chelate solution.

Automated summary

This study mainly investigated the effects of calcining temperature and time on the preparation of calcium sulfide from gypsum. It was found that gypsum could be completely decomposed into calcium sulfide by calcining at 900 degrees C for 30 min. Furthermore, the reaction between CaS and CO2 was observed to generate hydrogen sulfide, which could be oxidized to elemental sulfur.