Mining waste dumps are permanently incorporated in the landscape of the mining areas and exert an impact on the environment in many ways. The presence in the massif of a dump of carbonaceous substances often leads to the formation of fire hazards. Monitoring the activity of a newly created coal waste dump or of one under fire plays an extremely important role in fire prevention activity. Under the current regulations it must be carried out both during the exploitation process and for many years afterwards. Monitoring a dump is targeted, among others, at detecting thermal and gas anomalies already at the initial stage of development and to undertake preventive measures to eliminate and minimize the impact and load of a dump for the environment and the health and life of humans. In the article selected results of a research project (Raport 2011) are shown; a method of monitoring fire hazards at dump wastes was proposed, which includes thermal scanning and thermal-gas monitoring by a borehole method aimed at fixed points in the dump. Monitoring the large area of a dump requires exploration of the thermal state of a significant area hence the accepted scanning of the area is with a precision thermal imaging camera during an air raid. Then at selected sites of the dump, long-term in-field studies were conducted using the wireless data collection system from scattered test holes, made of perforated pipes and equipped with temperature and gas probes (CO, CO2, O2). At the same time the changes of environmental conditions and changes in atmospheric state parameters were observed around the dump, the so-called wind rose, based on data recorded by the weather station.
The article shows the results of research on methane concentration changes along mine galleries. The experiment was conducted in a longwall area mined using a U-type system, and the results were obtained in situ. The main goal was to measure methane concentration by function of gallery length and dividing segments of methane data into segments, which ultimately enabled separate analysis of these methane data. The analysis led to the diagnosis of methane hazard through the detection of exceedance of the assumed tolerance area.
The phenomena related to the occurrence of methane in underground mines pose a considerable danger in the process of coal seam exploitation. Quite often, experimental analysis falls short of investigating their areas of origin (goafs area, affected rock mass, the tail gate area with abandoned excavation). Therefore, an invaluable tool for evaluating the risk involved in the exploitation process might be the numerical simulation of the phenomenon in question, carried out with the use of the latest CFD methods. Due to its application, we are able to recreate and predict the mechanism of the studied phenomenon, with certain assumptions and simplifications made. The present paper discusses the results of the numerical simulation of the process of mass exchange occurring between affected rock mass and longwall headings. The calculations were performed for two test cases - 100 meter long walls.
The paper discusses the results of the numerical simulation of a sudden outflow of the air-methane mixture from behind a powered support, for a longwall ventilated by means of the U-type ventilation system. The calculations were performed using the geometrical model of an actual longwall - the I 100 longwall at the „Sośnica” hard coal mine. The steady state of the air flow in the area of the upper corner was discussed, together with the phenomenon of methane seepage from the goaf area in the vicinity of the longwall outlet. Subsequently, the phenomenon of a sudden methane outflow - followed by the ventilation of headings - was introduced into the study. The obtained results confirm the knowledge provided by the mining practice and experience
The aim of this research was to measure the filtration properties of waste coal ash under the influence of hydrostatic pressure generated in a three-axial compression apparatus. The scope of work included determining the compactibility parameters, maximum bulk density and optimal moisture content. Permeability tests were performed for a sample with an average grain composition at three compaction indices : 0.964, 0.98 and 1.00. The hydrostatic pressure ranging from 0.5 to 1.8 bar corresponded to the layer depths from 2.17 to 7.83 m. Gradually increasing the pressure during the first loading cycle caused irreversible changes in the structure of the sample by local material agglomeration or grain interlocking. The water permeability coefficient was higher in the second loading cycle than in the first cycle. It was shown that waste coal ash cannot be used as a construction material on its own. To obtain constant filtration properties, the waste coal ash material should be doped, or an optimal compactionshould be used ( = 1.00). The results presented in this study are important for assessing the use of waste coal ash for construction engineering purposes.
This article discusses the challenges of coal mine safety, particularly methane hazards, in the context of decreasing workforce and the need for more autonomous solutions. As hard coal production faces a phase-out due to international energy policies, the mining industry struggles with retaining skilled workers. The Sectional Methane Hazard Detection System (SDZM) is proposed as an autonomous solution to detect methane hazards by measuring methane concentrations along underground workings. The system operates using a series of algorithms that analyze the concentration data and identify hazard zones without the need for highly qualified personnel. The SDZM method involves collecting methane concentration data from different sections of the mining operation and comparing them to reference profiles to assess potential hazards. A study conducted in the 841A longwall area of KWK B mine used simulations to assess methane distribution, which was then used to test the SDZM system’s algorithms. The results show that the system can accurately detect high methane hazard levels, with sensitivity varying depending on the parameters set, such as the tolerance field for methane concentration changes. The study concluded that the SDZM system is effective in detecting methane hazards, requiring minimal additional skills from workers. The system’s performance can be enhanced by adjusting parameters like the methane concentration tolerance field, though excessively narrow tolerances could lead to false positives. Overall, the SDZM provides a valuable tool for enhancing safety in mines by autonomously identifying high-risk areas related to methane emissions.