Selective aggregation of fine copper minerals using charged polyacrylamides

Abstract

Selective aggregation can be used to improve the collection of fine valuable mineral particles often lost in industrial separation processes. This approach might be applicable to flocculate fine copper mineral particles such as chalcopyrite. It is hypothesised that the polymeric flocculant charge type will influence selectivity between chalcopyrite and waste minerals. This work investigates the use of charged anionic (APAM) and cationic (CPAM) polyacrylamides to selectively aggregate negatively charged chalcopyrite from its common waste (quartz). The interaction of the polymers with the mineral's surfaces as well as its flocculation capability were investigated through adsorption isotherms, turbidity tests, and in-situ aggregate size measurement. Furthermore, the ability to selectively aggregate and recover the valuable chalcopyrite from a quartz mixture by sedimentation was assessed. The results indicated that both charged polymers can be used to aggregate fine chalcopyrite particles, however, CPAM is non-selective towards the valuable mineral, as it also aggregates quartz. CPAM has a stronger affinity for both minerals, probably due to charge-charge interaction adsorption mechanisms, whereas APAM adsorption was lower, and more likely to be driven by hydrogen bonding. The interaction of APAM with quartz was limited probably because its highly negatively charged surface tends to repel the anionic polymer. Finally, the recovery of the chalcopyrite by sedimentation separation improved when using both polymers, but higher recoveries were obtained when using APAM.