Estudos de flotação de caulinita

Abstract

The increasing presence of kaolinite (main mineral which composes the kaolin ores) in bauxites and iron ores is a matter of concern. The search for methods to separate kaolinite, highly undesirable in the subsequent processes, from iron minerals is required. Very fine particles are originated from kaolinite in ore fragmentation operations. Flotation is presented as a possible kaolinite separation method in bauxites and ironores due to its applicability in a wide size range. Flotation is a separation process applied to solid particles which explores differences in surface characteristics amongst various present species. The objective of this work was the fundamental study of the variables involved (type and concentration of reagents, pH) in kaolinite flotation through microflotation tests in a Hallimond tube and zeta potential determinations. The tests were performed with a pure sample of kaolinite (96%). Six collectors weretested: 2-amino-1-hexanol (AH), Duomeen T (DT), cetylpiridinium chloride (CCP), cetyltrimethylammonium bromide (CTAB), dodecylamine (DDA), and Flotigam EDA (EDA). Four of them performed well as collectors, in the concentration of 1x10-4mol/L: CCP, CTAB, DDA and EDA. Collector DT presented efficiency in the recovery of kaolinite only for concentrations higher than 1x10-3mol/L. AH did not present efficiency in the flotation of kaolinite, probably, due to its short hydrocarbon chain. The isoelectric point determined for the kaolinite was at pH = 4.6. Likely the mechanism of adsorption of the reagents onto the mineral surface is through electrostatic and hydrogen bonds.