This research focused on assessing the chemical constituents of bauxite from Sangarédi, the dominant mining locality of Compagnie des Bauxites de Guinée (CBG), in an effort to assess the contributions of the constituents in deciding the final quality of exported products. Sampling was performed as a whole (from the deposit and intermediate stockpiled, and stockpiled for sale); then selected samples underwent analysis by x-ray fluorescence (XRF) in the laboratory. The study was completed based on alumina (Al2O3), and reactive silica (SiO2) whose variation can affect the sustainability and ultimately the profitability of a bauxitic ore in the Bayer process, which is the valorisation process of the ore.
The study results indicate that alumina is relatively stable, with an average content of 49.66 %, which is very much like the contractual specification of 50.01 ± 1.5 %; approximately 90 % of the samples fall within the acceptable tolerance range, and it shows that the ore has good export quality. However, reactive silica is unstable and too high, with an average content of 2.38 %, which exceeds the contractual specification of 2.01 ± 0.3 %; only 40 % of the samples conform with the standard, while 60 % are above the standard. This non-conformance created over-consumption of caustic soda and reduced alumina yield, which was detrimental to the international competitiveness of Sangarédi bauxite.
The proposed corrective actions are strengthening continuous quality control, improving stockpile homogenization, avoiding contaminations during handling and transport, and implementing differentiated deposit management.
In sum, this study has shown that controlling the variability of reactive silica is a tactical lever for better compliance with contractual specifications, enhancing the value-added of exported products, and consolidating Guinea’s role as the leading bauxite producer in the world.