Valorization of Aluminum Salt Slag Washed Residue in the Production of Portland Cement Clinker

The present research work focuses on the utilization of aluminum salt slag washed residue (SSWR) in Portland cement clinkerization. The initial Al salt slag was ground below 100 µm in order to recover the residual metallic Al. The ground salt slag was subjected to water leaching at various temperatures for the removal of soluble salts (NaCl, KCl). During the process of washing, about half of the nitrides were also decomposed. Different amounts of the washed residue were introduced in the raw meal before sintering at 1400 °C, fully replacing bauxite from the raw meal (4.5 %wt). The produced clinkers have been characterized by means of chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). After co-grinding with suitable amount of gypsum, the produced cements were evaluated by determining setting times, standard consistency, expansibility, and compressive strength at 2, 7, and 28 days. XRD analyses were used in order to determine the hydration evolution. Salt slag washed residue presents a promising alternative in waste valorization practice, as it can readily be used in the raw kiln feed as a partial replacement of ordinary raw materials. Graphical Abstract