The mining industry generates vast quantities of mine tailings on an annual basis. However, due to their limited economic value, a significant portion of these tailings are deposited close to mining sites, often underwater. The principal environmental apprehensions associated with mine tailings revolve around their elevated levels of heavy metals and sulfidic minerals. The oxidation of these sulfidic minerals can lead to the formation of acid mine drainage, which in turn releases heavy metals into nearby water systems. The effective management of tailing dams requires substantial financial investments for their construction and meticulous control. Consequently, a pressing need exists for stable, sustainable, and economically viable management approaches. One promising method for addressing mine tailings is through alkali activation, a technique that serves as a stabilization process. This approach yields robust, concrete-like structures by utilizing raw materials abundant in aluminum and silicon, which conveniently constitute the primary components of mining residues. This comprehensive review outlines the research on utilizing alkali activation for mine tailings. It delves into the reactivity and chemical attributes of diverse minerals. Numerous mine tailings exhibit an inadequate level of reactivity under alkaline conditions, so various pre-treatment methodologies and their impacts on mineralogy are meticulously explored.

Soil stabilization is vital in construction to enhance soil strength and durability. While conventional stabilizers like cement and lime improve soil properties, they contribute to significant carbon emissions. Given their widespread use, exploring eco-friendly alternatives is crucial. This review examines rice husk ash (RHA) and lime sludge (LS) as sustainable substitutes. Previous studies have evaluated their effectiveness in stabilizing clay soil, but a more application-focused approach, along with a detailed cost and sustainability evaluation, is needed. Standard Proctor compaction, California Bearing Ratio, and unconfined compression strength tests were analyzed from the existing literature to determine the optimal ratio of these additives for maximum soil strength. The results were compared to determine the most effective quantities of RHA and LS, either separately or combined, and inferences about their influences on clay soil attributes were drawn. Additionally, comprehensive life cycle assessment (LCA) and cost evaluation were reviewed. Finally, it was concluded that increasing the amounts of RHA and LS and combining them enhanced the strength of clay soil. Moreover, using RHA and LS for soil stabilization proved to be a cost-effective alternative to traditional methods, providing economic and environmental advantages.

Mining is a primary sector for the national economy of many countries, but exploiting these natural resources causes negative impacts on the environment. Tailings produced during mining, called mine tailings, have to be disposed of, and for that purpose, they are often mixed with Portland cement to control environmental toxicity and improve their mechanical properties. However, the high environmental impacts of producing Portland cement are well known. In this sense, sustainable binders based on the alkaline activation of industrial wastes have been studied as an alternative to using Portland cement. This study focused on applying a sustainable binder based on the alkaline activation of fly ash to improve the mechanical performance of a mine tailing from a mine located in Portugal. Geotechnical tests and chemical analysis were conducted to characterize the mine tailing and fly ash used in the alkaline activation process. In addition, triaxial tests were performed to evaluate the mechanical performance of the specimens, with both natural and stabilized tailings. The developed study proved that stabilized tailing with activated fly ash shows promising mechanical performance showing that this approach can be an excellent alternative to using Portland cement.

Copper mine tailings (CMT) are the waste material that remains after the economic fraction is extracted from the mineral ore and consist of a slurry of ground rock, water, and chemical reagents that remain after metallurgical processing. These tailings are considered toxic to the environment, so controlling their environmental toxicity and improving their mechanical properties are crucial. However, only a few studies have focused on assessing such performance by establishing the constitutive behaviour of the CMT. In this paper, we describe mine tailings properties and perform laboratory tests to calibrate clay hypoplasticity. Hypoplasticity is a constitutive model that includes concepts from Critical State Soil Mechanics, as a stress-dependent critical void ratio and a critical stress cone, according to Matsuoka-Nakai. The results show that hypoplasticity can well predict the mine tailings triaxial test behaviour. <!----> <!----> <!----> <!---->