Permeability refers to the ability of coal to transmit gas when a pressure or concentration gradient exists across it. The permeability of coal is dependent upon factors that include effective stress, gas pressure, water content, disturbance associated with drilling and matrix swelling/shrinkage due to adsorption/desorption. A programme of laboratory tests were conducted on coal samples from the Bulli seam for evaluating the permeability and drainability of coal. Two different types of permeability apparatus were used in this study. The methods of permeability testing of coal under different triaxial conditions are discussed. Permeability testing of the Bulli seam coal with N2 is described. The laboratory test results were found to be in agreement with the calculated permeability values, Naj Aziz, Ting Ren, Jan Nemcik and Lei Zhang., and Obsahuje bibliografii
The purpose of this work was to detect groundwater pollution and to identify the conditions of soil and groundwater near the coal waste disposal "Panewniki" Halemba-Wirek Coal Mine using geoelectrical measurements. The firs t applied method was the VLF (Very Low Frequency) technique. This method, using military signals, allowed to perform the in-phase and the quadrature maps. Data were collected from four study areas located near the coal waste dump. Observed anomalies on both maps for each area showed places with different conductivity al lowed to detect the contaminated and uncontaminated zones. The VLF survey indicated that the contamination occurs in the eastern part of study area and is characterized by positive values of both measured electrical fields (the in-phase and the quadrature components). After preliminary contaminated zones were recognized using VLF met hod, an electrical imaging meth od was applied. Two electrical imaging profiles were carried out near the waste dump. The measurements a llowed to create the geoele ctrical model of surrounding area and to investigate the leachate plume. The electrical imaging showed that the greatest pollution occur in the area immediately adjacent to the coal waste what is confirmed by VL F survey. Based on the geological and ge ophysical knowledge from archives and on present researches, the contaminated aquifer with electrical resistivity of 5 to 15 Ω m deposited at depths of 3 to 7 m was found., Arlena Kowalska, Marta Kondracka and Maciej Jan Mendecki., and Obsahuje bibliografické odkazy