Sustainable Management of Mine Tailings through Geopolymer Production and Accelerated Carbonation

Abstract

This dissertation investigates two sustainable methods for managing mine tailings (MT) with the goal of reducing environmental impacts and enhancing the stability of tailings storage facilities. The first part of this research focuses on the development of acid-resistant geopolymer binder and concrete using MT with various additives. The geopolymerization process converts MT into valuable construction materials, which can be utilized within the mining industry and beyond. A series of laboratory tests, including unconfined compressive strength (UCS), acid resistance, permeability, water absorption, and flexural tests, were conducted to assess the performance of the geopolymer products. In addition, mechanochemical treatment was applied to enhance the reactivity of MT, improving both the physical and mechanical properties of the resulting geopolymer binder and concrete. The results demonstrate that the geopolymer products produced from MT exhibit superior physical, mechanical, and durability properties, addressing the limitations of traditional ordinary Portland cement (OPC) products.The second part of the dissertation investigates the accelerated carbonation of MT for the dual purpose of sequestering CO2 and mitigating acid mine drainage (AMD). By injecting CO2 and AMD into the MT, the mineral carbonation process is enhanced, leading to the stabilization and solidification of heavy metals and contaminants within the MT. This process not only sequesters CO2 but also strengthens the MT, improving the structural stability of tailings storage facilities. X-ray diffraction (XRD) analysis and thermogravimetric analysis (TGA) were conducted to characterize the MT before and after carbonation and evaluate the degree of carbonation by considering the different carbonate compounds, calcite, dolomite, siderite, and magnesite. The UCS test was conducted to investigate the enhancement of MT strength after carbonation. Microstructural analyses were also performed to investigate the interaction between MT and these carbonate compounds. Furthermore, the study determined the amount of CO2 that can be captured by MT based on carbonation, offering a comprehensive solution for mitigating AMD, stabilizing MT, and sequestering CO2. Together, the two approaches investigated in this dissertation offer sustainable solutions for MT management, helping to mitigate environmental impacts, lower long-term MT management costs, and support the mining industry’s compliance with environmental regulations.