The effect of residual coagulants and flocculants in process water on the flotation performance of a selected Cu-Ni-PGM ore

•Dewatering aids in process water increased the stability of the froth.•Dewatering aids in process water increased mineral recoveries.•The acrylamide acrylate co-polymer in process water had the most influence.•The effect of AAC could be overcome in the presence of polyquat and CMC. The implementation of closed water loops within mineral processing circuits has become a key feature of concentrator design and configuration owing to the need to use and manage water resources efficiently. This however does not come without challenges. As the water is recovered from tailings and concentrates thickeners and filters where dewatering chemical agents are added, its recirculation and re-use in froth flotation may alter the process due to the presence of residual coagulants and flocculants being introduced into the process. This study considers the use of process water containing residual concentrations of a coagulant and flocculant on the flotation behaviour of a Cu-Ni-PGM Ore. Water recirculation is mimicked through the addition of various amounts of polyhydroxyalkylene dimethyl ammonium chloride and acrylamide acrylate copolymer as the flocculant and coagulant respectively. The findings of this study showed that dewatering aids in process water increased the stability of the froth as seen through increased water and solids recoveries. Dewatering aids in process water also increased mineral recoveries and decreased the concentrate grades. The acrylamide acrylate co-polymer flocculant in process water had the most influence on flotation performance.