Beneficiation and upgrading of coarse sized low-grade bauxite using a dry-based fluidized bed separator

Abstract

Beneficiation and upgrading of low-grade bauxite is important to the subsequent extraction of Aluminum metal using Bayer process. The mineralogical characterization of diaspore bauxite sample used in this work was performed using various analysis approaches. The results indicated that the major components of raw sample were diaspore and kaolinite. The bauxite samples had high Al2O3 contents with low Al/Si ratios. A dry-based fluidized bed separator with FeSi powder as dense medium was used to beneficiate coarse sized bauxite. The basic fluidization tests suggested that −0.18 + 0.125 mm FeSi powder was appropriate for the fluidization stability, thus utilized as the dense medium for separation. The beneficiation experiments of various sized bauxite samples were investigated under various operational factors of separating time, static bed heights, and operational gas velocities. The upgrading performance of coarse sized bauxite indicated that the satisfied grade of concentrate could be obtained with a reasonable recovery of concentrate. Al/Si ratios were improved to 3.19, 4.53, and 3.66 for the bauxite samples with size fractions of −13 + 6 mm, −18 + 13 mm, and −25 + 18 mm, respectively. This work provided an alternative efficient method for the pretreatment of low-grade bauxite via discharging coarse waste gangue.