# A Comprehensive Review on Mine Tailings as a Raw Material in the Alkali Activation Process
## 5 Conclusions  
Mine tailings constitute the largest volume of solid waste generated by the mining industry. Unfortunately, due to their limited economic value, a significant portion of these tailings are typically deposited in controlled landfills submerged underwater. The landfilling of mine tailings has not always been viewed as a significant problem. However, their environmental impacts, especially incidents like tailing dam failures leading to tailing draining or flooding, have resulted in severe consequences, including a loss of life, leading to the issue gaining critical attention. Consequently, stringent legislative regulations have compelled the mining industry to explore alternative methods of disposal. The possibility of employing mine tailings as a primary material in alkali activation has garnered significant attention from researchers. Among the crucial factors for examination, the mineral composition of mine tailings takes precedence. Predominantly, these tailings exhibit low levels of reactivity under alkaline conditions based on their mineralogy. Therefore, using them as a raw material in alkali activation proves to be challenging due to this inherent low level of reactivity. Mine tailings can be effectively employed as an inert filler in alkali activation technology, especially when combined with a compatible co-binder, like metakaolin, fly ash, or blast furnace slag. Factors such as curing conditions, the duration of curing, the type and concentration of the alkali activator, and the choice of co-binder materials all exert pivotal influences on this process. Sustainable high-performance building materials can be created that leverage waste materials for environmental and economic benefits and that can be tailored to specific requirements by adjusting the mix design and using different types of aluminosilicate precursors. An alternative approach involves enhancing the reactivity of the initial material through methods like thermal treatment, mechanical activation, or alkaline fusion before subjecting it to alkali activation. Alkali-activated mine tailings hold potential applications as construction materials and as recyclable paste backfill materials. Furthermore, this method can serve as a stabilization approach before landfilling, particularly for managing hazardous mine tailings. Finally, future studies on mine tailing alkali-activated materials could focus on optimizing activation processes to enhance the mechanical and durability properties of mine tailings. Moreover, performing life cycle assessment (LCA) analyses to develop sustainable and efficient activation methods by understanding the long-term environmental impact and stability of these materials should be considered.  
**Author Contributions:** Conceptualization, H.R.M., E.P., N.C. and T.M.; methodology, H.R.M., E.P., N.C. and T.M.; formal analysis, H.R.M., E.P. and T.M.; investigation, H.R.M., E.P. and T.M.; resources, E.P., N.C. and T.M.; writing--original draft, H.R.M.; writing--review and editing, H.R.M., E.P., N.C. and T.M.; supervision, E.P., N.C. and T.M.; project administration, E.P., N.C. and T.M.; funding acquisition, E.P., N.C. and T.M. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the \"NGS-New Generation Storage\" project (reference number C644936001-0000045), financed by the Recovery and Resilience Plan and the Next Generation EU European Funds.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors would like to thank the Recovery and Resilience Plan and the Next Generation EU European Funds for funding this project.  
**Conflicts of Interest:** The authors declare no conflicts of interest.