A study on thermal and electrical characterization of Barapukuria coal of northwestern Bangladesh

The thermal and electrical studies on the recent discovery of Barapukuria coal of northwestern Bangladesh have been carried out to elucidate the characteristics of this shallow basin coal. In addition to that electrical study, proximate analyses were performed using standard methods for rank classification. Coals are found to have low moisture, low ash, medium–high volatile matter and high calorific values and on the basis of that coals are classified as mixture of medium and high volatile bituminous coal. The dc electrical resistivity has been determined as a function of applied voltage, thickness and temperature using the ASTM standard (D 257-78) methods. For voltage variation measurement from 0 to 200 V both lump and powder compact disc samples were used. The lump samples cut parallel and perpendicular to the bedding planes were used to specify the basic structural unit (BSU) of the micro domains. It is observed that variation of resistivity is not highly affected by voltage but trend to decrease. The resistivity increases as the thickness increases and resistivity is greater when the sample oriented perpendicular to the bedding plane than that of samples oriented parallel to the bedding plane, which implies that the coals are electrically anisotropic. The results obtained have been found very similar to those of some Indian, USA (Illinois basin) and USSR (Lisichansk) in terms of their electrical characteristics. The temperature variation resistivity study reveals that the Barapukuria coals are mostly semiconductor in nature.