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Acid-Generating
Potential of Coals from Benue
Adene, T. M., University of Ibadan, Ibadan, Nigeria
Much attention has been focused in recent years on coal as an
alternative source of energy. Currently, exploration and exploitation of coal
particularly in the Benue Trough of Nigeria have been
intensified with a bid to diversifying the economy, which has been almost
solely dependent on oil and gas. In assessing the quality of coal, it is always
essential to study the acid generating potential, and these have been
undertaken on some selected coal samples from outcrop, boreholes and mines
within the Benue Trough of Nigeria. This is to rank
some of the coals occurring within the trough into acid producing and stable
non-acid producing rocks. Coal ash samples were also analyzed for reactive sulphur contents and their base potential as well as degree
of weathering quantified by the chemical index of alteration (CIA).
The results indicate that the coals from lower (LBC) and middle
(MBC) Benue Trough are likely to produce acid, while
the main alkaline producing coals are from the upper (UBC) Benue
Trough. The coal ash has the potential to be a problematic acid generator with
high CIA values ranging between 64.9 to 97.5%, low proportion of base
neutralizing cations (CNK) in an A-CNK-FM ternary
plot with values ranging between 2 to 19% and high reactive sulphur
content of greater than 3.4kg/tonne.
The information
obtained from this study could be utilized in the management of existing and
potential coalmines for control and treatment of acid mine drainage in the Benue Trough. It could also assist with local, regional and
international energy resource evaluation, environmental and health assessment.