Mixtures of Sodium Iso-Butyl Xanthate and Sodium Di-Ethyl Dithiophosphate on the Flotation of a Cu-Ni-PGM Ore in Ca(NO₃)₂ and NaNO₃

The use of mixtures of thiol collectors has been said to be of benefit for the flotation of Cu-Ni-PGM ores. However, the increasing demand on the use of recirculated water in minerals processing may alter the performance of flotation reagents. This therefore places the need for flotation reagents to be understood in terms of their behaviour in different components or constituents of process water, as is necessary with regards to better decision making in terms of understanding the quality of process water that works for reagents and specific ores, as well as the quality of water. Ca²⁺ and Na⁺ are common cations in process water and are said to bring various effects in the pulp phase and the froth phase and have become common subjects of investigations where water quality is concerned. NO₃^- anions however have not received much research attention as compared to other common ions in process water, such as Cl^-, SO₄^2- and S₂O₃^2-. NO₃^- ions are said to result from the blasting chemicals used during mining and are leached into solution during milling and can therefore be considered key role players (as far as the interactions occurring in the pulp phase are concerned). Their interactions in the pulp phase and their role in flotation should therefore be important to consider. This paper presents results from bench-scale froth flotation tests which were conducted on a Cu-Ni-PGM ore from the Merensky reef using mixtures of thiol collectors, namely sodium isobutyl xanthate and sodium diethyl dithiophosphate in solutions containing Ca(NO₃)₂ and NaNO₃. NaNO₃ solutions showed higher solids recoveries at all thiol collector mixtures as compared to Ca(NO₃)₂ solutions. Higher Cu and Ni recoveries were seen in NaNO₃ solutions at all thiol collector mixtures.