Geology and Petrography of Ibobo Coal, Anambra Basin, Nigeria

Abstract

Coal is a combustible material consisting mainly of macerals and minor minerals. Macerals are the microscopic organic entities of coal while the inorganic components are the minerals. Maceral composition is vital for assessing the quality of coal and predicting its behaviour in metallurgical, combustion and other processes. It also helps to understand the geological history of coal deposits. Geological mapping of Ibobo coal deposit in the Anambra Basin of Nigeria was conducted and coal samples evaluated for maceral characteristics and vitrinite reflectance to determine the suitability of the coal for metallurgical processes and electricity generation. Petrographic analysis reveals the presence of the three maceral groups; vitrinite, liptinite and inertinite in all the samples. The proportion of the vitrinites and inertinites are higher than the liptinites in the samples. On mineral matter-free basis, the coal, on average, contains 60.80% vitrinite, 12.70% liptinite and 26.50% inertinite. With mineral matter counted, on average, it consists of 51.70% vitrinite, 11.40% liptinite, 23.10% inertinite and 13.80% mineral matter. The coal, on average, also contains 63.10% reactives (vitrinite + liptinite) and 36.90% inerts (inertinite + mineral matter). It has mean vitrinite reflectance measurement of 0.42 RoMax on average, which classifies the coal as sub-bituminous. These petrographic characteristics suggest that the coal does not possess coking qualities suitable for coke making for metallurgical processes thereby placing it on low quality and non-coking. However, it is good for electric power generation and as a domestic fuel.