Self-cementation of gold tailings activated by nonthermal plasma irradiated calcium (hydro)oxide.

ABSTRACT

The alkalinity of CaO is commonly insufficient in alkali-activating raw soils or minerals for the formation of cementation or geopolymerization. In this study, nonthermal plasma (NTP) irradiation was employed to activate traditional CaO to enhance its efficacy in alkali activation and further intensify the self-cementation of gold tailings. The solidification/stabilization (S/S) of the gold tailings-based matrix activated by NTP-CaO was better than that of CaO. The NTP irradiation enhanced the surface hydroxyl groups and oxygen atoms, decreased the binding energy, formed nanoparticles, and significantly changed the morphologies of the calcium activator. The dosage of the NTP-irradiated CaO (NTP-CaO) directly affected the self-cemented solidification/stabilization of gold tailings. The Johnson-Mehl-Avrami-Kolmogorov model was appropriate for analysing the NTP-CaO-activated geopolymerization kinetics of gold tailings. Three-dimensional (3D) structural minerals covered with small pores were determined in the NTP-CaO-activated cemented samples. The employment of NTP-CaO facilitated the formation of aluminosilicate geopolymers during the self-cementation of gold tailings according to comprehensive characterization strategies. The study achieves the efficient self-remediation of gold tailings by activating calcium precursors, which further solves the contradiction between salinization and alkali activation in the field of noncalcined cementitious materials.