Browsing by Author "Naidoo, Omeshan"
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- ItemInvestigation of the effect of compositional variations on the flotability of pyrite in a gold ore(Stellenbosch : Stellenbosch University., 2020-03) Naidoo, Omeshan; Tadie, Margreth; Von der Heyden, Bjorn; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH ABSTRACT: Gold is associated with pyrite, arsenopyrite and arsenian pyrite in refractory gold ores. Due to the presence of arsenic or other compositional variations in the pyrite, the semiconductor properties are expected to differ from that of bulk pyrite. Semiconducting properties play a role in the attachment of a flotation collector to the mineral surface, an improvement in recovery in froth flotation may be possible if the compositional variations of pyrite can be related to the optimisation of collector reagent suites in froth flotation. The project aim was to relate the variation in pyrite composition to its impact on recovery in a flotation system and the effectiveness of reagent suites in overcoming the challenges presented by compositional variations in valuable mineral recovery. Batch flotation of are fractory ore from the Barberton Greenstone Belt in South Africa, using SIBX, PAX and SIBDTP as collectors is investigated as a case study for this phenomenon. Two different “pure” pyrite samples were floated in a micro-flotation cell to fundamentally study the differences in flotation of different pyrite samples. Pyrite in the case study ore had, among others, compositional variation of differing amounts of arsenic within the pyrite. Gold in the case study ore was associated with pyrite containing high arsenic content. SIBX and PAX in batch flotation achieved a pyrite recovery of 30.63% and 38.25% respectively, while SIBDTP recovered 27%. SIBDTP only recovered 20.97% of gold compared to 70.97% by SIBX and 73.89% by PAX. SIBDTP recovered less gold because SIDTP was shown to selectively recover pyrite with no arsenic or a low weight percentage arsenic, compared to SIBX and PAX which selectively recovered pyrite with a higher weight percentage arsenic. Compositional variations in pyrite thus impacted the recovery of the pyrite in the batch flotation system via the selective attachments of different collectors to pyrite with different compositional variations. Pyrite samples for micro flotation showed trace amounts of copper and lead (Pyrite 1) and cobalt (Pyrite 2). Pyrite 1 and Pyrite 2 differences extended to zeta potential measurements, where Pyrite 2 showed a zeta potential of approximately 10 mV lower across the pH range than Pyrite 1. Even though variations were present, no trends of differences were seen between the two pyrite samples in micro-flotation recovery.When SIBDTP and the Xanthates were mixed, an increased recovery of pyrite was seen over single collectors alone. Collector mixtures of 75% SIBX and 25% SIBDTP (massbasis) in batch flotation recovered the most pyrite (69.92%) at the highest pyrite grade (6.4%) with the most gold recovered(100%) at the highest gold grade (50.6g/ton). A recovery increase of up to 5.88% of pyrite after 20 minutes of microflotation was observed with 25% SIBDTP and 75% xanthate.The result of increased recovery of pyrite in batch flotation and inmicro-flotation with 75% xanthate and 25% SIBDTP lead to the conclusion of collector mixtures are beneficial to the recovery of pyrite when applied in the correct ratio and can overcome the mineralogical barrier posed by varying compositions.