ASSESSING COAL-BED METHANE POTENTIAL IN MALAWI: CASE STUDY OF MCHENGA COAL MINE

The aim of this study was to assess the potential of coal at Mchenga coal mine for coal-bed methane generation. This was carried out by using proximate data that included moisture, volatile matter, ash, and fixed carbon content of four coal samples from varying coal seams of K2 upper formation at Mchenga coal mine. Volatile matter on a dry ash free basis was used to estimate methane content and calculate vitrinite reflectance of the four coal samples.

Microsoft Excel software was used to analyze the results, and the analysis indicated that based on the values of volatile matter on a dry ash free basis and vitrinite reflectance, the coal samples under study belong to the subbituminous coal rank. This is according to the coal rank classification table by Teichmüller (1982) and Diessel (1992).

The values of vitrinite reflectance also indicate that the coal samples under study have the potential to generate coal-bed methane gas. However, since the coals belong to the subbituminous coal rank, the generation of the gas is in its early stage. In addition, when the estimated methane content was correlated with moisture, fixed carbon on a dry basis, and volatile matter content, a negative correlation was observed. Conversely, a positive correlation was observed when it was correlated with fixed carbon on a dry ash free basis and vitrinite reflectance.

Therefore, based on the results and the analysis, it was suggested that the coal samples from the study area have the potential to generate coal-bed methane gas. This information will help the mine authorities to come up with appropriate mitigation measures for the mine against any potential gas disaster explosion that are caused by the presence of coal-bed methane in a coal mine. Hence, further exploration for coal-bed methane can be carried out in the study area, in order to determine the exact quantity of the gas and its production potential.