The coal exploitation in the Upper Silesia region (along the Vistula River) triggers the strata seismic activity, characterized by very high energy, which can create mining damage of the surface objects, without any noticeable damages in the underground mining structures. It is assumed that the appearance of the high energy seismic events is the result of faults’ activation in the vicinity of the mining excavation. This paper presents the analysis of a case study of one coal mine, where during exploitation of the longwall panel no. 729, the high energy seismic events occurred in the faulty neighborhood. The authors had analyzed the cause of the presented seismic events, described the methods of energy decreasing and applied methods of prevention in the selected mining region. The analysis concluded that the cause of the high energy seismic events, during the exploitation of the longwall panel no. 729 was the rapid displacements on the fault surface. The fault’s movements arose in the overburden, about 250 m above the excavated longwall panel, and they were strictly connected to the cracking of the thick sandstone layer.
This paper describes the concept of controlling the advancement speed of the shearer, the objective of which is to eliminate switching the devices off to the devices in the longwall and in the adjacent galleries. This is connected with the threshold limit value of 2% for the methane concentration in the air stream flowing out from the longwall heading, or 1% methane in the air flowing to the longwall. Equations were formulated which represent the emission of methane from the mined body of coal in the longwall and from the winnings on the conveyors in order to develop the numerical procedures enabling a computer simulation of the mining process with a longwall shearer and haulage of the winnings. The distribution model of air, methane and firedamp, and the model of the goaf and a methanometry method which already exist in the Ventgraph-Plus programme, and the model of the methane emission from the mined longwall body of coal, together with the model of the methane emission from the winnings on conveyors and the model of the logic circuit to calculate the required advancement speed of the shearer together all form a set that enables simulations of the control used for a longwall shearer in the mining process. This simulation provides a means for making a comparison of the output of the mining in the case of work using a control system for the speed advancement of the shearer and the mining performance without this circuit in a situation when switching the devices off occurs as a consequence of exceeding the 2% threshold limit value of the methane concentration. The algorithm to control a shearer developed for a computer simulation considers a simpler case, where the logic circuit only employs the methane concentration signal from a methane detector situated in the longwall gallery close to the longwall outlet.