Leong, YK, Bensley, SJ, Drewett, J & Burkett S 2023, 'A cost-effective tailings solution to rheology issues while meeting the environmental constraints using inexpensive additives', 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. 580-587, https://doi.org/10.36487/ACG_repo/2355_43
A significant quantity of tailings is produced in the wet beneficiation of iron ore. These tailings are flocculated and thickened in a thickener before being pumped to a tailings storage facility TSF, i.e., a pond, which can be several km away. Occasionally, the thickened tailings acquired a higher yield stress than can be pumped. This material then becomes a bottleneck reducing the plant output. This study demonstrates how to reduce these problematic tailings’ yield stress or viscosity with a cheap additive. NaOH costing ~ US 400 per tonne resulted in a 50-60% reduction in the yield stress at pH 10 and ~ 90% reduction in the viscosity at 100s-1. The legislated environmental constraints are i) the pH of the disposed of tailings must be less than 10 and ii) any chemical leachate of heavy metal ions must be less than stock drinking water guidelines or water table water. Leaching results showed this was the case for all leachate chemicals evaluated up to pH 11.2. Some leachate chemicals evaluated were As, B, Cr, Cu, Mo, Pb, Se, Th, Ti, U and V. However, not all tailings (from different mines) respond to NaOH treatment.
Keywords: rheology control, composite additives, leachate, heavy metal, dry stacking, filtration
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