Aquatic risk assessment based on the results of research on mine waters as a part of a pilot underground coal gasification process

Abstract

One of the possible applications of available hard coal resources is their underground gasification directly in the deposit. The gas obtained in this way is discharged to the surface for use in chemical synthesis or energy purposes. The environmental risk of the technology is mainly related to the potential negative impact of the process on groundwater and surface water, due to the need to remove process condensates and the drainage of the exploitation area. The risk occurs both during the process and after its completion. This article presents the results of a pilot study carried out in the Wieczorek Mine. The coal gasification experiment was carried out over 6 months (with 2 months of gas extraction) in real conditions in a georeactor located 450 m below the surface and on the surface of the object (cooling and cleaning system for gasification products). Water monitoring was carried out before the experiment, during the experiment and 5 years after the end of the process. The analysis includes the results of underground and surface water monitoring within the range of the potential impact of the pilot plant. The paper also presents the analysis of water-tar condensate collected from the gas cleaning system.