Stabilization of gold mining tailings with alkali-activated carbide lime and sugarcane bagasse ash

Abstract

Recent tailings dam failures have attracted special attention to the mining sector. These incidents pressured the mining industry to develop more secure and sustainable practices. Geotechnical techniques, such as soil stabilization with ordinary Portland cement (OPC), have been explored as alternatives to this problem. However, OPC production is associated with high energy consumption, exploration of natural resources, and greenhouse gases emission. Thus, alternative materials to OPC, with lower environmental impacts and similar mechanical performance, are growing in interest for stabilization techniques. The present study describes the mechanical behavior of gold tailings stabilized with alkali-activated carbide lime and sugarcane bagasse ash. As a control group, the gold tailings were also stabilized with high initial strength Portland cement (type III). The specimens were tested regarding their unconfined compressive strength, stiffness, and durability. All results were correlated with the porosity/binder index to create a rational dosage methodology for the tailings-cement mixtures. Results have shown that Portland cement mixtures resulted in more expressive strength, stiffness, and durability results when compared to the alkali-activated cement. Nevertheless, the alternative cement was also able to improve the mechanical behavior of the gold tailings. Reduction in porosity and increase in cement content led to the improvement of the mechanical behavior of all specimens. A direct correlation was established between strength, stiffness, and durability. The porosity/binder index was shown to be a viable dosage method to predict the mechanical behavior of stabilized gold tailings, allowing the unification of the results in a single relation, replacing trial and error conventional strategies.