The kaolinite presence in bauxite ores increases the caustic soda consumption during the digestion step in the Bayer process. Depending on the kaolinite content, the utilisation of the ore in the Bayer process may be unfeasible. This investigation addressed the variables involved in kaolinite flotation through microflotation experiments in a Hallimond tube and zeta potential determinations. The tests were performed with a pure sample of kaolinite (96%). Five collectors were tested: Duomeen T (DT), cetylpiridinium chloride (CPC), cetyltrimethylammonium bromide (CTAB), dodecylamine (DDA), and Flotigam EDA (EDA). Four of them performed well as collectors, in the concentration of 1x10-4 mol/L: CPC, CTAB, DDA and EDA. The DT collector was effective in the recovery of kaolinite only for concentrations higher than 1x10-3 mol/L. The kaolinite isoelectric point (IEP) was determined at pH = 4.6. The IEP was shifted towards higher pH values in the collectors presence, indicating specific adsorption onto the mineral surface.
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