Leaching behaviour, kinetics and reactivity of calcined drilling cuttings in low-alkaline environments: Experimental and mechanistic insights

Abstract

This study comprehensively investigates the leaching behaviours and kinetics of calcined drilling cuttings (CDCs) in low-alkaline environments. It delves into how varying concentrations of NaOH, leaching durations and temperatures impact the leaching ratios of key elements such as Si, Al, Ca and Fe from CDCs. Advanced analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDS) and backscattered electron imaging and analysis (BSE-IA), are used to characterise the phase composition, microstructure and reactivity of CDCs. The results indicate that NaOH concentration, leaching time and temperature considerably influence the leaching behaviours of CDCs, with temperature being the dominant factor. The leaching kinetics analysis reveals that CDC leaching is governed by reactant diffusion, with activation energies for Si and Al determined to be 32.29 and 26.72 kJ/mol, respectively. BSE-IA sheds light on the distribution of different phases within the CDCs and their reactivity order (Phase I > Phase II > Phase III). This study demonstrates that CDCs can be used as supplementary cementitious materials in cement systems, although further assessment of their environmental risks is necessary. This research lays a solid theoretical foundation for the application of CDCs as cement admixtures and proposes a method for the rapid evaluation of their reactivity.