Potential use of iron ore tailings for binder production: A life cycle assessment

Abstract

Iron ore tailings (IOT) are generated in large-scale around the world and are stored in its slurry form generating risks of dam failure. The stabilization of this tailings by cementing agent provides a better mechanical capacity for stockpiling. Alkali-activated cement (AAC) can be used due to its versatility in the use of waste for its production, thus reducing environmental impacts. In this context, the present work brings the use of iron ore mining waste for an alternative production of a binder. The IOT Binder uses a differentiated production of sodium silicate with tailings (from flotation process) and production of metakaolin with mining overburden. To evaluate the environmental efficiency of IOT Binder product, an environmental Life Cycle Assessment (LCA) is performed and compared with a conventional production of alkali-activated cement, using commercial products, for mining tailings stabilization. Eleven environmental impact categories are used for the evaluation of the IOT Binder and conventional AAC production inputs and their application for tailings stabilization. Preliminary compressive strength tests were performed with IOT Binder in the stabilization of iron ore tailings from Brazil. LCA results indicate that IOT Binder is more environmentally sustainable than conventional alkali-activated cement due to its lower energy consumption and avoidance of natural resource use. In addition, it is effective in cementing and stabilizing iron ore tailings for possible use in dry stacking.