Utilization of phosphate fertilizer industry waste for belite-ferroaluminate cement production

Phosphogypsum (PG) and pyrite cinder (PC) are phosphate fertilizer industry wastes. At present, the utilization of PG and PC is limited, their stockpiling brings about serious environmental problems. We studied the manufacturing technique for producing belite-ferroaluminate cement utilizing of PG and PC as raw materials instead of natural materials. The mechanical properties, mineral composition and microstructure of the resulting cement clinker were investigated using X-ray powder diffraction (XRD) with Rietveld quantitative phase analysis, scanning electron microscope (SEM), etc. We found that burning at 1250 degrees C for 60 min was suitable for clinker production. The effect of natural gypsum (NC) content on setting time, heat evolution, compressive strength, hydration products of cements were also investigated. The results show that setting time of cement depends much on NC content. The early hydration accelerates with NC content increasing. The effect of NC content on compressive strength at different curing age is variable. NC content in cement is also an important factor in the hydration products. (C) 2012 Elsevier Ltd. All rights reserved.