Leaching Behavior of Alkali-Activated Gold Tailings Over Wetting-Drying Cycles

Alternative binders produced from waste for the stabilization of mining tailings (especially those considered hazardous) are important for waste management and sustainable engineering. Thus, this manuscript evaluated the leaching behavior of gold mining tailings stabilized/solidified by an alkali-activated binder (AAB) over wetting-drying cycles of durability test. The alternative binder is composed of sugarcane bagasse ash, carbide lime and sodium hydroxide. As a control group, the mining tailings were stabilized/solidified using Portland cement. In general, AAB showed favorable results in encapsulating Al, As, Ba, and Fe, while Portland cement exhibited effectiveness in the immobilization of Al, Ba, Fe, and Hg. For both AAB and Portland cement, higher dry unit weights and binder contents led to the encapsulation of metals in cemented mining tailings matrices. Samples with 30% AAB and 16.5 kN m-3 dry unit weight presented concentrations of Al, As, Ba, Cu, Fe, Hg, Se and Zn below the limits of all water standards. Alkali-activated binder from industrial waste was shown to be a new option to encapsulate contaminants from gold mining tailings.