The Possible Causes of Thermal Variations of Coals in Dilbi-Moye Basin, Jimma Zone, Oromia National Regional State, Southwestern Ethiopia
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Date
2009-07
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Addis Ababa Universty
Abstract
The coal deposit of Dilbi-Moye Basin in southwestern Ethiopia, between 70 21'
49" - 70 24' 31" N latitude and 360 50' 21" - 360 52' 54" E longitudes was studied
with regard to sedimentological, geochemical, depositional environments and
possible causes of thermal variations of the basin, which have a total area of
31.94 km2.
The chemical analyses of the coal samples for the proximate, calorific value
and sulfur content of the coals, different graphs are plotted versus each other
to depict the coalification pattern, and the possible thermal variations of the
Dilbi-Moye Basin.
From the analyzed coal samples result, the rank of Moye Sub-Basin coals
range from sub-bituminous to high volatile A bituminous coals; whereas the
Dilbi Sub-Basin coals range lignite B through high volatile B bituminous coals.
The majority of the coal seams in the Moye area exhibited higher ranks due to
the proximity of volcanic extrusions.
There is no uniform increment of the calorific values and decreasing of the ash
content or vice versa in the Dilbi-Moye coals. However, in some cases, it is
observed that as the calorific value increases, the ash content also increases
and vice versa, across the basin.
Therefore, the possible causes of the thermal variations of the coals of the
basin might be in most cases the organic matter (genesis) of the fossil fuel
and/or environment of deposition and partially the inclusion of inorganic
material into the coal. However, in some coal seams, the increment of the
calorific value emerges from the near-by trachytic or rhyolitic sills that
cooked the underlying seams to have high heating values
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Keywords
Dilbi-Moye