Life cycle assessment of emerging processes to valorize mining waste

Abstract

Globalization and ever-increasing growth of human progress require a continuous supply of materials, notably metals, to sustain these developments. However, metals production inadvertently generates environmental burdens due to tailings. These are the waste from metallurgical processing to separate unwanted materials from metal ore deposits and are disposed of in storage facilities. Despite advancements in metallurgical processing, there are still a fraction of metals lost in the tailings and they pose long-term pollution risks. Valorization of tailings are therefore having a twofold impact: First, metals leftover recovery can minimize the discharge of toxic metals into the environment. Second, after the purification process, the ground materials in the form of mineral matrices are another potential resource that could be exploited, thus reducing the need for primary production. However, the valorization technique requires processes causing environmental impacts and therefore we apply life cycle assessment (LCA) to account for tradeoffs. LCA enables evaluation of energy, materials, and waste along product life-cycle stages. Based on state-of-the-art upscaling frameworks in the metallurgical processing domain, we perform a case of prospective LCA for the alkali-activated materials fabricated by mechanochemical activated mining wastes. In this study, we develop systematic procedures to leverage bench-scale experiments into industrially optimized facility by means of process simulation. As takeaways, a comparative analysis is presented for the case studies with maturity levels. Ultimately, the results will be the critical inputs for process designers in steering the developments towards sustainable use of mine tailings.