Study of the parameters of spontaneous fire seats in coal pit rock dumps

Abstract

The presence of coal and coal-bearing rocks in waste rock dumps of open-pit coal mines contributes to the occurrence of spontaneous combustions that negatively affect the environment and people. Measurements of the temperature and the content of hazardous gases in the temperature anomaly that arose in the waste rock dump of the open-pit coal mine were made to assess the parameters of spontaneous fire seats. In the course of the study, the efficiency of detecting spontaneous fire seats in waste rock dumps was assessed by measuring the rock temperature in the wells with a depth of 2.5 m, drilled at a distance of 20 m from each other. The experiment showed the difficulty of drilling control wells in waste rock dumps and the impossibility of drilling them on the slopes of dumps, especially in spontaneous fire seats with a high rock temperature. The necessity of casing control wells with pipes makes it difficult to measure the rock temperature at different depths. It was found that there are sharp drops in the rock temperature in the heated area of the dump, which cannot be detected when the wells are located at the recommended distance. The measurements showed that in all wells the temperature increases with depth, therefore the depth of wells recommended by the regulatory documents does not allow determining the size of the heated area.

Remote detection and monitoring of post-mining heat island

“…Several investigations of coal waste heaps and tailings ponds with high temperatures are described in the literature, carried out by various methods, mainly by direct methods. Fire can be identified by examining the presence of emitted gases, for example, by gas chromatography of collected samples (Fabiańska et al, 2018;Nádudvari et al, 2021b;Karacan et al, 2021;Nádudvari et al, 2022;Singh et al, 2022) or by measuring the temperature directly in a heap spot-wise with a pyrometer (Kruszewski et al, 2018;Allen et al, 2019;Protasov et al, 2021), or using thermal imaging cameras and thermal image analysis (Abramowicz and Chybiorz, 2019;Sobocińska and Sobociński, 2019;Nádudvari et al, 2020;Nádudvari et al, 2021a). However, these methods require researchers to be present in a hazardous area.…”