Amazonian Kaolin Purification by Selective
C.H. Sampaio*, F. Larroyd, C.O. Petter, W. Aliaga
Mineral Processing Laboratory, Center of
Technology, Federal University of Rio Grande do Sul, P.O. box 15021, ZIP 91501-970, Porto
Received 26 April 2002; accepted 15 June 2003
most important kaolin deposit in the north of Brazil presents titaniferous contaminants
finely disseminated in the bulk. Those contaminants affect the commercial value of the
mineral urging a process for removing them. The removal of those contaminants can not be
carried out by conventional techniques, due to the ultra-fine size of the minerals.
This paper presents a mineral concentration process based on selective adsorption of
soluble polymers. Flocks of considerable sizes and quite consistent are generated by
interactions between anionic polyacrylamide molecules and titaniferous minerals which can
be separated from a kaolin suspension by sedimentation.
The best results were obtained after a polymer, having a weak anionic charge (10%), was
used as flocculant for kaolin impurities. The mineral was dispersed in aqueous media using
a high concentration of sodium hexamethaphosphate (4.8 Kg/t) at a pH value around 10. In
these conditions, the content of TiO2 in the sample was reduced from 1.39% to
less than 0.5% and kaolin recoveries ranged between 50 and 65%. Sedimentation of the
flocks reached rates around 5.2 mm/min.
Keywords: Kaolin; Selective flocculation; TiO2
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