Youll, JC, Leong, YK & McFarlane, AJ 2023, 'The effect of composite additives on the rheology of concentrated iron ore tailings and their components', in GW Wilson, NA Beier, DC Sego, AB Fourie & D Reid (eds), Paste 2023: Proceedings of the 25th International Conference on Paste, Thickened and Filtered Tailings, University of Alberta, Edmonton, and Australian Centre for Geomechanics, Perth, pp. 822-827, https://doi.org/10.36487/ACG_repo/2355_65
(https://papers.acg.uwa.edu.au/p/2355_65_Leong/)
Abstract: The major components of iron ore tailings produced in the Pilbara region are hematite, goethite and kaolinite. At times, these tailings have developed a viscosity or yield stress too high for the pump to handle. This rheological problem urgentlyrequires a cost-effective and simple solution. To address this issue, this study evaluates the yield stress-solids concentration relationship of iron ore tailings, ochreous goethite sourced from a Pilbara mine, and kaolin suspensions with and without the composite additive NaOH-Na2SiO3-Na polyphosphate. Our results reveal that the yield stress-concentration curve shifts to a higher concentration for all three materials when the additive is above a critical level. At 0.5 dwb% (g/100g solids) of the composite additive, the yield stress was close to zero at 65 wt% solids for all three suspensions. This indicates that iron ore tailings can be transported at a concentration in excess of 65 wt% solids by using the composite additive. The cost required to process tailings of 55 to 65% solids was between USD 2 to USD 4 per ton of solids, although the additive dosage’s optimisation was outside this study’s purview. The tailing viscosity and yield stress can be converted back to paste consistency with a neutralising additive for safer storage in the dam or as a feedstock for dry stacking, i.e., drying, harvesting and stacking.

Keywords:  Rheology control; composite additives, goethite, kaolin, hematite