Abstract:
Bauxite is the main raw material in primary aluminum production and its reactive silica content and mass ratio of Al2O3 to SiO2 (A/S) has a critical role in the economic viability of Bayer process. As a major source of the reactive silica, clay impurities should be removed from the ore as much as possible by a beneficiation method such as froth flotation before the Bayer processing. The success of the beneficiation method largely depends on geological origin and mineralogical composition of the bauxites. In this study, low-grade bauxite ore from Seydişehir (Konya, Turkey) containing 57.33% Al2O3 and 9.01% SiO2, (A/S = 6.36) was investigated to determine the modal mineralogy and mineral liberation with regard to the removal of reactive silica by flotation. Mineralogical studies showed that the principal bauxite mineral was boehmite interlocked with clay minerals (kaolinite and illite), ferruginous minerals (hematite and goethite) and titanium bearing minerals (e.g. rutile and ilmenite). By reverse flotation of the ore, a high-grade bauxite concentrate with A/S ratio 8.54 was obtained, however the Al2O3 recovery remained low at 42.87%. Although the A/S rate achieved by the flotation was adequate for the Bayer process, Al2O3 recovery was considered to be low for flotation process. It was deduced that the separation of reactive silica by flotation with plausible recovery was difficult, largely due to the complex mineralogy and poor mineral liberation. © 2020 Elsevier Ltd