Shaocong Zheng

PHOSPHOGYPSUM AS A RAW MATERIAL FOR THE PRODUCTION OF SO2 AND LIME IN CIRCULATING FLUIDIZED BEDS

The primary objective of this research is to investigate the possibility of producing sulfur dioxide and lime from phosphogypsum (PG) in a circulating fluidized bed (CFB) on a pilot scale. Thermal decomposition of PG was conducted in a CFB using anthracite as the reducing agent and fuel at temperatures in the range 900–1100°C. The gaseous decomposition products, which mainly consist of sulfur dioxide, were analyzed using a gas analyzer and X-ray diffraction. The results indicate that the reaction conditions required to produce sulfur dioxide and lime are an air flow rate of 94 m3/h, a temperature of 1100°C, and a PG consumption rate of 120 kg/h. Under optimal conditions, the maximum concentration of sulfur dioxide in the flue gas reached 8.2% (vol. %), and the maximum CaO concentration in the phospholime reached 62.57% (wt. %).