Advances in Alternative Binders for Iron Ore Pellets

The replacement of bentonite as the standard iron ore binder is an important factor in the future of iron processing. Bentonite adds unwanted silica to the final concentrated iron ore product. Excess silica from bentonite addition has been calculated to consume approximately 2.4 MJ of additional energy during the production of one metric ton of pig iron. Bentonite replacement requires an in-depth understanding of how alternative binders affect the agglomeration process. Starch has shown promise as a potential replacement binder for bentonite; other alternatives such as fly-ash have also been considered. Starches with solubilities ranging from 7.5-60% have been investigated as partial and full bentonite replacements. These starches have been found to allow for potential reductions in bentonite dose by 75%. Direct replacement of bentonite with starch yields pellets of sufficient quality for industrial use. Starch can be used as a direct replacement for bentonite; however, starch is significantly more expensive making direct xxi replacement cost prohibitive. Partial replacement of bentonite with 1 kg/ton starch was found to be a viable option. When using starch as a supplemental binder, pellets can be made that meet all minimum industrial standards for strength and maintaining a binder cost that is less than that of bentonite alone. The current state of knowledge presents significant gaps to be explored regarding the use of starch during pelletization. The proposed work will focus on the importance of starch solubility when starch is used as a binder, the impact of the absorption of water by starch, and the binding mechanism of starch during agglomeration. This work will rely heavily on microscopy techniques such as optical microscopy, scanning electron microscopy and energy dispersive spectroscopy