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.

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. 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 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.

Mchenga Coal mine is located in the south eastern side of the Livingstonia coalfield found within Rumphi district, in the northern region of Malawi. Livingstonia coalfield extends over 90km2 within the district, while the coal mine extends over 17.5km2 within the coalfield (Maneya, 2012).

Mchenga coal mine is an underground mine which uses room and pillar mining method, and almost all the underground mining sections have well-built canopies and accessible adits (Umali et al., 2016). Room and pillar mining method is used because it is suitable and appropriate for the rocky terrain and stability of the hanging walls in the Livingstonia coalfield, within which the coal mine is found (Umali et al., 2016).

Mchenga coal mine falls within latitude: S10°42'55", longitude: E34°9'14" and is the second largest mine in the country, after the Kasikizi coal mine (Yasidu et al., 2019). The mine produces 0.3 million tonnes per annum and has mineable reserves that amount to 26.5 million tonnes, where 1.5 million tones are proven reserves and 25 million tonnes are probable reserves (GlobalEnergyMonitor, 2022).

District: Rumphi

Coordinates: -10.82575, 33.942