The analysis of natural hazards, including gas-geodynamic phenomena, requires study of the basic physical processes that take place at each stage of an event. This paper focuses on analysing the transport of fragmented rock material during rock and gas outbursts. Our theoretical considerations and experiments have allowed us to specify and verify the significant forces acting on fragmented rock during its transport, thus determining the speed of grains of each grain class in the stream of expanding gas. The above study may serve as a preface to a wide-ranging quantitative and qualitative energy analysis of the movement of material ejected during Gas-geodynamic phenomena.

Rock and gas outburst is a phenomenon in which fragmented rock material is transported deep into a pit. The transport of rock material by gas is a two-phase process. The article deals with the fluidisation of rock material. Considerations on the fluidisation phenomenon were carried out, and experiments were performed to help clarify whether the fluidisation of dolomite is possible. In the last chapter, a discussion was carried out, and the results obtained were analysed regarding the possibility of occurrence in mine conditions.

The paper presents research on the influence of grain size of selected coals and their structural parameters on the diffusion coefficient and methane sorption isotherms. Two coals from Polish hard coal mines, differing in the coal rank, were tested. Sorption isotherms for methane were determined. An unconventional sequence of pressures 0→0.1→0→0.5→0→1.5 MPa was employed to assess the speed of achieving sorption equilibrium at different pressures. The studies of CH4 accumulation kinetics were performed on various grain classes of the tested coals. Both the sorption capacity of coal and the diffusion coefficient proved to be highly sensitive to the experimental methodology. Critical measurement parameters in terms of determining the diffusion coefficient concerning the assumptions of the Crank model were indicated. The influence of the equivalent radius of coal grain on the process kinetics was demonstrated. The stepwise pressure increase factor was examined in the context of minimising the impact of sorption isotherm non-linearity on the results. The importance of the width of the grain class of coals was determined to reduce their maceral inhomogeneities. These factors are the most common reason that makes it difficult to quantitatively compare diffusion coefficient values.