Low-CO2 Cements from Fluidized Bed Process Wastes and Other Industrial By-Products

According to the findings of X-ray diffraction analysis, calcium looping (CaL) spent sorbent (as a main source of CaO), anodization mud (as a source of Al2O3 and additional sulfate), and fluidized bed combustion (FBC) fly and bottom ashes, separately or in mixture (as main sources of CaSO4 plus alumina and uncarbonated lime) can replace limestone, bauxite, and gypsum as components of calcium sulfoaluminate (CSA) clinker-generating raw mixes. All of the hydrated CSA cements obtained from the corresponding clinkers and investigated by means of differential thermal-thermogravimetric analysis displayed a similar behavior. It has been demonstrated that the well-recognized environmentally friendly character of CSA cement manufacture can be further improved not only by using industrial wastes instead of natural materials, but also by virtue of the reduced CO2 emission and increased energy saving associated with the limestone substitution with poorly carbonated sources of lime, such as CaL spent sorbent and FBC ashes.