Grinding Behavior and Potential Beneficiation Options of Bauxite Ores

Abstract

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 (fc) 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 Al2O3. In this fraction, the Al2O3 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.

Research on the Selective Grinding of Zn and Sn in Cassiterite Polymetallic Sulfide Ore

“…When the grinding concentration was lower than 50%, there was little difference in the breaking behavior between Zn and Sn minerals; however, when the grinding concentration was higher than 50%, the Zn minerals were preferentially broken prior to the Sn minerals. (2) The relative changes in the cumulative quantities of metal for both Zn and Sn increased as the particle size decreased, indicating that the ability to selectively crush Zn and Sn minerals both decreased as the particle size became finer, which was consistent with the results of the changes in the cumulative grade.…”

“…In the grinding process, minerals with high hardness experience less fragmentation, which results in a coarser particle size, while minerals with low hardness suffer greater fragmentation, which results in a finer particle size. This phenomenon is called mineral selective grinding [1,2]. In the past ten years, few studies have investigated the selective grinding phenomena and its application to manganese ore, molybdenum ore, fluorite, andalusite, talc, cassiterite, and waste circuit boards [3][4][5][6][7].…”

Modeling of Bauxite Ore Wet Milling for the Improvement of Process and Energy Efficiency

“…The resulting sodium aluminate-rich liquor is separated by physical means, such as settling and filtration, from the insoluble residue, known as bauxite residue. Typically, depending on the type of bauxite used, 1 t of alumina results in the generation of residues varying from 0.3 t for high grade to 2.5 t for very low-grade bauxite [9,10].…”

“…These deposits are hosted within carbonate rocks belonging to the Mediterranean karst bauxite belt. Greek bauxite ores are mainly composed of gibbsite (Al(OH) 3 ), diaspore (α-AlO(OH)), and/or boehmite (AlO(OH)), while kaolinite (Al 2 Si 2 O 5 (OH) 4 ), hematite (Fe 2 O 3 ), goethite (FeO(OH)), titanium oxide (TiO 2 ), and silicon oxide (SiO 2 ) are also present as impurities [10].…”

“…Pretreatment using mineral processing techniques is considered a necessary step to separate aluminous minerals from the impurities. One of the most common techniques for upgrading bauxite ores is froth flotation (direct or reverse) using various reagents [12][13][14], while magnetic/gravimetric separation, reductive roasting, or selective grinding followed by magnetic separation has also been used over the years [10,[15][16][17].…”