Browsing by Author "O' Connor, Cyril"

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    Synergistic effects between thiol collectors used in the flotation of pyrite
    (1997) Bradshaw, Deidre Jane; O' Connor, Cyril
    This thesis investigates, firstly, whether synergism occurs between the thiol collectors, potassium n-butyl xanthate (PNBX) and cyclohexyl dithiocarbamate (cyclohexyl DTC) when a mixture of these collectors is used in the flotation of pyrite at pH =4 and, secondly, why synergistic effects are observed, if any. The focus of the investigation was a 90:10 mole ratio mixture of PNBX and cyclohexyl DTC, although other collector ratios were compared in the batch flotation tests. This ratio was chosen to test the effect of a small amount of the one component in a manner synonymous with studing thermodynamic excess pro.perties. The high cost of dithiocarbamate collectors also argued in favour of the ratio. The effect of copper sulphate on the flotation performance obtained with pure cyclohexyl DTC and PNBX as well as with the collector mixture was also investigated.
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    Synthesis, characterisation and olefin oligomerization over nickel, cobalt and zinc substituted synthetic mica montmorillonite
    (1996) Vogel, Alex Philip; O' Connor, Cyril
    Nickel, cobalt and zinc were substituted for structural octahedral aluminium in SMM. X-ray diffraction, together with elemental analysis, confirmed that a 2: 1 layered aluminosilicate had been formed. The inclusion of these metals facilitated the crystallisation of the SMM structure in the synthesis process as was shown by their more well-defined X-ray diffraction patterns over unsubstituted SMM synthesized in this work. The 2: 1 layer spacings increased at nickel contents of 16 and 34wt%, indicating a more montmorillonite-like structure. Cobalt levels at 33wt% were seen to disrupt the basal spacing. The opposite effect was seen with zinc, where increased zinc loadings caused the 2: 1 layers to be drawn closer together. This was indicative of a more micalike structure.