During excavation of lignite in the Velenje Coal Mine coalmine, seam problems with gas outbursts occur. Geochemical investigations are designed to help predict, prevent, and manage coal mine gas outbursts and to study their origin and mechanisms. Temporal changes in chemical and isotopic composition of “free” seam gases were observed as a function of the advancement of the working face –120/B, G2/C and –50/B within boreholes jpk-28/10, jpk-30/10, jpk-31/10, jpk-22/09 and jpk-23/09. Mass spectrometry and isotope mass spectrometry methods were used to determine gas composition and perform gas characterization. Coalbed gases in the Velenje basin are highly variable in both their concentrations and stable isotope composition. Major gas components are CO2 and methane. Concentrations and isotopic studies revealed several genetic types of coalbed gases: endogenic CO2 (including CO2 originating from dissolution of carbonates), microbial methane and CO2.
COBISS.SI-ID: 25317159
Laboratory study of adsorption-desorption characteristics of various lignite lithotypes is very important for prevention of coal dust and gas outbursts that represent a dangerous and unpredictable phenomenon in underground mining of the Velenje lignite. The performed study consists of adsorption investigations carried out in the geotechnical laboratory of the Velenje Coal Mine (VCM). Lignite samples contained in the reaction cell were exposed for a limited time to a gas pressure of up to 100 bar. The measurements were performed on an updated instrument according to the improved volumetric gas sampling method. The gas was sampled from the reaction cell during the sorption simulation. Updating of the instrument affected positively the data quality. The performed three sets of measurements led to results that were crucial for further research. In the experiment, the amount of adsorbed and desorbed gas was calculated from the pressure difference in the known cell volume. The obtained results could permit the risk assessment of possible coal dust and gas outbursts.
COBISS.SI-ID: 950878
The paper concerns the development of a formalism of the movable cellular automata method for simulation of consolidated heterogeneous elastoplastic media at different scale levels. Using the developed formalism as the basis, an approach was formulated for construction of structural models that describe mesoscopic response (including fracture) of heterogeneous media to loading with regard to hierarchical organization of their internal structure. In the approach, the effect of structural scale levels higher than the level under consideration is taken into account by a technique combining the particle method and conventional methods of continuum mechanics. The effect of lower structural scale levels is taken into account by determining integral response characteristics of lower-scale representative volumes and by specifying appropriate values of particle interaction parameters. The proposed formalism was advanced for description of contrast heterogeneous media whose components can assume different aggregate states. The potentialities of the particle method for description of hierarchically organized media are illustrated by studying the response and fracture mechanisms of materials, including contrast media, with a developed porous structure.