Heat shock evidences within dust particles after explosion in coal mining

Abstract

In situ coal samples and coal dust explosion samples were taken with the aim to determine the raised temperatures and the transformation grade of the coal dust during an explosion in two underground mines in Colombia. One of them exploited thermic coal (Region 1) and the other coking coal (Region 2). These samples were observed under the microscope of reflected normal and fluorescent light; some polish sections of coal dust and the char obtained from the degasification at 950°C in the laboratory, were observed and also analyzed with scanning electronic microscopy SEM-EDX to determine the morphologic characteristics and chemical composition. The thermic effect was observed in the absence of oxygen in the organic matter, in which is possible to visualize the evidences of degasification and the char and coke formation, as well the mineral matter, with the presence of melted minerals. The results indicate that the coal dusts from the Region 1 are in general fewer explosives than the coal dusts from the Region 2, also the calorific value is a parameter influencing the explosivity, but not so volatile matter. Every type and coal rank presents different characteristics compared to the explosivity and therefore cannot be generalized.