Structural and textural characteristics of selected copper-bearing rocks as one of the elements aiding in the assessment of gasogeodynamic hazard

The characteristics of copper-bearing rocks that include the structural and textural parameters are an important factor determining a possible gas accumulation in those rocks. In September 2009, in the Rudna copper mine in Poland, an outburst of gases and dolomite occurred. The analysis of the outburst mass showed that one of the main causes of the outburst was the different structural properties such as high porosity and presence of gas in the pores. This paper presents data from the structural analysis of dolomite from the Polkowice-Sieroszowice copper mine and the Rudna copper mine. Seven rock samples from various areas of the mines were tested by the following methods: mercury porosimetry (MIP), low pressure gas adsorption (LPNA), scanning electron microscopy (SEM), computed microtomography (micro-CT). The SEM analyses of the rock samples allowed pores of various sizes and shapes to the observed. The porosity (MIP) of the dolomite changed in the range of 3–15%. The total micro and mesopore volume (LPNA) was from 0.002 cm³/g to 0.005 cm³/g. The macropore volume (MIP) was from 0.01 cm³/g to 0.06 cm³/g and the mean macropore diameter was from 0.09 μm to 0.18 μm. The dolomite samples varied in the surface area (LPNA) (0.7–1.5 m²/g) and the pore distribution. The structure of dolomite determines the possibility of the occurrence of gasogeodynamic phenomena and hence it is urgent that research be conducted into its changeability. To better understand the gasogeodynamic processes in copper-bearing rocks, it is necessary to constantly monitor and analyse in detail those areas that have different structural properties.