Grinding Behavior and Potential Beneficiation Options of Bauxite Ores

This laboratory study investigates selective grinding and beneficiation options for a Greek bauxite ore. First, a series of batch grinding tests were carried out in order to investigate the grinding behavior of the ore and the effect of the material filling volume (f c) on the distribution of aluminium- and iron-containing phases. Then, the ground ore was subjected to magnetic separation either as received or after reduction roasting in order to further explore potential beneficiation options. The results showed that grinding of the ore exhibits non-first order behavior, while the breakage rate varies with grinding time. Additionally, Al2O3 tends to concentrate in the coarser than 0.300 mm product fraction, while fc 10% and 2 min of grinding time are considered optimum conditions for good distribution of Al2O3 and Fe2O3. When different product fractions were subjected to magnetic separation, it was seen that the non-magnetic product obtained from the 0.300–1.18 mm fraction was more rich in Al 2O3. In this fraction, the Al 2O3 content increased from 58 wt% in the feed to 67.9 wt%, whereas the Fe2O3 content decreased from 22.4 wt% in the feed to 13.5 wt%. When the ore was subjected to a two-step treatment, involving reduction roasting followed by magnetic separation, the Fe2O3 grade decreased from 20.8 to 5.1 wt%, but in this case the recovery was very low.