Reuse of Iron Exploitation Waste as a New Binder for Tailings Stabilisation in Dry Stacks: Circular Economy ApproachKeynote

The dried allocation of the tailings, rather than the disposal in a slurry form, appears as an alternative to attend new legislation and improve the safety of mines operation. Also, the use of cementing agents in dry stacking facilities can enhance aspects of operations such as guaranteeing dilatant behaviour at the base and increasing tailings’ strength. The present research assesses the technical and environmental viability of a new alkali-activated cement (AAC) in iron ore tailings stabilization. The mechanical response of compacted tailings-AAC specimens was evaluated through strength and shear modulus tests while Life Cycle Assessment (LCA) was performed to verify the sustainability of this new binder when compared to conventional AAC. This new binder is derived from the residues of iron exploitation and is intended for use in new disposal schemes, such as dry stacks. The AAC is mainly composed of metakaolin (MK), produced from the residual soil removed during the mining activity, and sodium silicate (SS), produced with sandy tailings. Using tailings and waste in AAC production aligns with sustainable practices, minimizing resource consumption and promoting waste recovery. Also, LCA demonstrates a lower impact for tailings AAC when compared to conventional AAC. In addition to environmental and mechanical aspects, using this AAC supports the application of circular economy in mining since it enables the reuse of waste produced in mine operation as a substitute for conventional cement (that involves another industry and raw materials).