Water Re-use from Tailings on the Flotation Performance of a Cu-Ni-PGM Ore

Recycling of process water recovered from tailings dewatering unit operations in mineral processing has become a topical issue owing to the chemistry of recycled water being different from fresh water and how this difference may affect grinding chemistry in the mill, flotation chemistry, and the potential impact on flotation performance. This study examines the impact of recycled water addition to the mill on the flotation performance of a low-grade Cu-Ni-PGM ore over three successive cycles. Synthetic plant water of known ionic strength and composition was used as the baseline. Results showed that while water recovery and froth stability increased with recirculated water, the relationship with solids recovery was not linear suggesting reduced entrainment and a decoupling of froth stability from mineral recovery. Moreover, Cu recoveries showed slight improvement with recycling, while Ni recoveries showed a slight decrease. Significant variation in the accumulation of Ca²⁺, Mg²⁺, Cl⁻, and SO₄²⁻ was observed between recirculation strategies, affecting the electrical conductivity. The findings of this study highlight the importance of understanding water chemistry changes within closed-loop systems and its intersection with grinding and flotation processes. Insights from this study can inform water management strategies and reagent schemes that support both metallurgical performance and environmental compliance in PGM concentrators.