Radon in the investigations of geo‐hazards in Polish collieries

Abstract

Outbursts (releases of gas and coal from exposed coal face) are dangerous events in coal mines, potentially leading to damage in the galleries and casualties among miners. For that reason, monitoring of this hazard is very important in collieries with seams prone to outbursts. Current hazard indicators are not sufficient for the proper prediction of geodynamic events and any effort to find a new and better method of monitoring is thus desirable. During the 1980s and 1990s, attempts were undertaken to apply specific radiometric methods to support the prediction of outbursts in collieries in the Lower Silesian Coal Basin (LSCB) in south-western Poland. This idea was developed as an analogy to the study of radon changes in groundwater prior to earthquakes. This study investigates the hypothesis of possible variations of radon emanation from coal seams prior to outbursts. Techniques and a methodology of radon observation in gas samples from strata were developed and applied. It has been stated that there is a degree of correlation between the temporal and spatial variations of radon level and the hazard level of an outburst. In the 1990s, all collieries in LSCB were abandoned and further investigations were thus stopped. In the last few years, the occurrences of outbursts were noticed in the collieries of Upper Silesian Coal Basin. For that reason, we initiated the monitoring of radon concentration as sampled from headings in dangerous coal seams. The purpose of the research is an attempt to introduce a new parameter, 'the radon indicator of outburst hazard', which could be used to support other routinely applied techniques of outburst prediction. This study provides some results from previous investigations performed in the collieries of the LSCB, as background and calibration to the preliminary results of the new research, performed in one of the coal mines in Upper Silesia region.

Radon Research in Poland: A Review

“…underground hard coal and copper mines in southern and south-western Poland (the Upper Silesian foredeep and the Sudetes) are also interesting. The values measured in hard coal mines oscillate in the range from tens to 150, 000 Bq/m 3 [37,55]. At the same time, 222 Rn activity concentration in salt caverns in copper mines, at the depth of about 1000 m b.s.l., range from 12 to 49 Bq/m 3 [38].…”

“…Measurements of 222 Rn activity concentration in the atmospheric air, soil air, the air of buildings, caves and other underground tourist sites as well as working underground mines are also performed with the use of devices that are well known in the world and have been tested in various conditions. These are, first of all, Alpha GUARD and RAD7, but also scintillation chambers, Lucas cells and semiconductor detectors used in all Poland-made devices such as different series of mining radiometers RGR [33][34][35][36][37][38]. Besides, new appliances dedicated to measuring 222 Rn activity concentration in different environments are also being developed in Poland.…”

“…Research into this issue is still continued [37]. Also, a possibility of using 222 Rn as a precursor of earthquakes is investigated in the underground geophysical laboratory in Książ in the Sudetes.…”

Radon release from underground strata to the surface and uniaxial compressive test of rock samples

“…(c) Coal and gas outburst prediction. Wysocka (2010) started observations of changes of radon concentration in gas, sampled from headings, driven in endangered coal seams. Then, he reported that there is a degree of correlation between the temporal and spatial variations of radon level and the hazard level of an outburst, and it is possible to develop a "radon outburst's indicator" to support other methods of prediction of very dangerous geodynamic phenomena.…”

On the Merits of Modified Sublevel Caving Mining Method – A Case Study

“…Mining water contaminated with harmful elements may also penetrate ground waters [16][17][18][19][20]. in her work, Wysocka described the problem of radon emissions following underground coal mine closures and the harmful impact of such emissions on residents [21]. Mine closure by flooding also results in additional significant changes to the stress and deformation of the rock mass, manifesting on the surface as continuous [6,22,23] and discontinuous [24] deformations, and may also be observed as mining damage [4,23,25].…”