Analysis of the diversity of hard coal mines in poland in terms of their methane, seismic and coal dust explosion hazards

Underground hard coal exploitation is accompanied by a series of natural hazards. Their number and intensity increase along with the growing depth of exploitation. Amongst the most dangerous hazards in the mining industry, one can distinguish the following: methane hazards, seismic hazards (including the rock-burst hazard) and coal dust explosion hazards. They are a common issue in Polish coal mines, thereby making it necessary for coal mines to identify the level of these hazards. It can also be assumed that there are similar risk levels in some coal mines. This, in turn, makes it possible to apply similar measures in order to improve the situation. The article presents an analysis aimed at determining the diversity of Polish hard coal mines in terms of their methane, seismic and coal dust explosion hazards. The variables that describe the scale of the methane hazard include the absolute methane content and the ventilation methane content. In the case of the coal dust explosion hazard, it is the amount of the stone dust used for dusting the headings. The variable describing the rock-burst hazard is the value of the tremor energy. The analysis presented in the paper was carried out for 2016 data and encompassed 23 hard coal mines located in the area of the Upper Silesian Coal Basin (GZW). The analysis was conducted using one of the hierarchical grouping techniques, namely the Ward's agglomeration method. This method made it possible to isolate homogeneous subsets of the items under analysis (mines), adopting the Euclidean distance as a measure of similarity. The analysis included a total of 8 variables describing each of the mines. The mines were grouped into clusters, depending on the degree of similarity in terms of the hazards analysed. The results obtained pave the way for cooperation between coal mines with similar risk levels. This should result in greater effectiveness of the relevant measures, thereby enhancing safety in these enterprises.