In my presentation I would like to overview interesting research problems related to two data mining competitions recently organized at Knowledge Pit platform. Data for both of those competitions were acquired within the frames of the DISESOR project from active Polish coal mines and the tasks were related to monitoring of safety conditions. In my talk, I will briefly describe the competition tasks. I will also discuss some of the most interesting solutions to the first of the competitions which ended in the second half of June, 2015. Finally, I will refer to our own ideas related to feature extraction and selection methods developed for the purposes of analyzing the described data.