COMPARATIVE STUDIES ON BENEFICIATION OF BAUXITE SAMPLES FOR APPLICATION IN REFRACTORY INDUSTRY

摘要

An attempt has been made in the present study to beneficiate bauxite ore from Durgamanwadi mines of M/S NALCO to achieve a grade of the products conforming to refractory specification which is maximum at 2.5 percent Fe_2O_3 and 4.0 percent TiO_2 after calcination so as to avoid adverse effect. These two bauxite samples differ in their Fe_2O_3 content, which is low in case of Durgamanwadi (3 - 5 percent) and very high in ease of Panchpatmali (25 - 35 percent). The mineralogical study reveals that gibbsite is the aluminium bearing mineral in case of Durgamanwadi sample, whereas Panchpatmali sample consists of gibbsite, kaolinite, sill imanite as major phase. The iron bearing minerals are goethite, hematite limonite and magnetite for Durgamanwadi and limonite hematite and limonite for Panchpatmali sample.The gravity and wet magnetic separation methods were adopted for beneficiation. The materials were stage crushed and classified into sand and slime fractions before the beneficiation studies.Durgamanwadi and Panchpatmali mines samples require classification of the bauxite into sand and slime fraction before beneficiation of the sample using gravity and magnetic separations. The beneficiation of Durgamanwadi sample results in the product which match with the specification of refractory bauxite. For Panchpatmali sample, the table concentration is effective in reducing Fe_2O_3 and TiO_2 contents of the bauxite sample in case of coarse fraction. Magnetic separation it not effective as only a meagre portion of the bauxite is rejected through this treatment as magnetic fraction. In case of slime fraction, however, appreciable separation has not been achieved through tabling, possibly due to hetero-coagulation of the particles. The result on magnetic separation is also not encouraging. Mineralogical evidence suggests that pre-treatment of the bauxite sample (roast reduction) may be required before magnetic separation.