A study of physicochemical characteristics of respirable dust in an Indian coal mine

The respirable coal dust samples were collected from the mine atmosphere during drilling of coal seams using 'Hexlet' apparatus. Sixteen dust samples were collected from each three different seams for investigations. After destruction of the organic matter by wet oxidation and filtering off the clay and silica, Fe, Ca, Mg, Na, K, Mn, Zn, Cu, Cd and Ni were determined directly in the resulting solution by atomic absorption spectrophotometric methods. The x-ray diffraction studies have shown the presence of kaolinite, quartz, pirrsonite, and beidellite clay minerals in the coal dust. The mass-size distribution of the coal dust has been studied by using micron photosizer. The results showed that the distribution are unimodal, asymmetric, and positively skew. Although the assumption of log-normality was useful in interpreting the results, closer observations indicated that the relationship between the size and weight of the particles can be represented by a second degree parabolic equation w = a + bS + cs2, where W and S are weight and size of the particles and a, b and c are constants. This equation helps us to characterise the mass of the respirable particles if the size is known. The studies throw light on the nature and mode of trace elements found in Indian Coal as well as on the causes of respiratory disease, pneumoconmiosis, affecting the workers in the mine environmental condition.