Abstract:
Bauxite, which is the main raw material that aluminium is extracted from was discovered in Africa in
the early 1900s. Currently, the production and export capacities of the African Bauxite ore are about
a third of the World’s total capacity. However, the processes leading to the final finished product of;
surface mining of the ore, refining ore into alumina and finally extracting the pure aluminium metal
in high energy consuming smelters that employ the Hall-H´eroult electrolysis process; seldom take
place inside Africa. The main goal of this work is to analyse the mineralogical and geochemical
characteristics of bauxite deposits from some prominent bauxite producing and exporting countries
of Africa in order to fashion out if a trend exist for the type of source rocks. Judging from the data
obtained, gibbsite is found to be the main aluminium oxide in all the bauxite deposits with slight
occurrence of boehmite in 3 out of the 13 deposits, while goethite is the main oxyhydroxide iron
mineral. The compiled results of the various investigations highlighted the fact that the deposits are
of diverse qualities with respect to world standard of major element content of bauxite; with average
percentage concentration in the ranges as: Al2O3 (43.73–61.25), Fe2O3 (1.55–34.25), SiO2
(0.42–10.84); except two of the deposits with alumina content less than 40%. With evaluated silica
moduli less than 8 for only two (2) of the deposits (4.76 and 6.94), the rest have higher moduli that
ranges between (14.49 and 75.45). The higher percentage of iron oxide content (>20) in six (6) out
of the 13 ore deposits, allowed the deposits to be grouped into three (3) categories of grades; high
alumina ore, ferruginous ore, siliceous ore and combination of each. Source rock of the deposits were
determined through geochemical and petrographic considerations of laterisation products of the
rocks through evaluation of the weathering indices of; Chemical Index of Alteration which was in the
range (97.16–99.98) while the Ruxton ratio ranged between (0.0133–0.2100); signifying the parent
rock underwent intensive weathering process. This is indicative of the source rocks of the Bauxite
deposits being either (i) anorthositic, (ii) argillite and dolerite, (iii) granulite and feldspathic gneiss,
and/or, (iv) mafic-basaltic andesite igneous. Awareness of new and yet-to-commence emerging
bauxite producing African countries was created, by highlighting the economic impact those
respective countries will experience when that mining sector is developed for the aluminum in dustry at home and world at large.
