Characterization and Ore Dressing of Bauxite from Brazil

摘要

The Bauxite from North Brazil is characterized by a geological profile with different layers. The differences among these layers are percentage of bauxite constituents (gibbsite, kaolinite and hematite). Nowadays, only one layer is used for alumina production by Bayer process, the commercial or crystallized bauxite. This work intended to characterize and to ore dress crystallized bauxite (CB), amorphous crystallized (MB) and nodular bauxite (MNB) from Para to make them usable in the Bayer process. The ore dressing was developed by mechanochemical activation with an alkaline reagent in different concentrations and conditioning time. After ore dressing, the samples were submitted to characterization by X-ray diffraction (XRD), X-ray fluorescence (XFR) and Theological characterization. CB and MB ore dressing products were characterized by an increase of mass ratio Al_2O_(3available)/SiO_(2reactive) and it was observed that the total silica of MNB, after ore dressing, decreased around 13%. These results were a strong indication that these bauxites could be used in the Bayer process.