Application of the underground treatment of mine waters in underground galleries in 'Piast' mine

In underground coal mines in the Upper Silesian Coal Basin there are inflows of highly mineralised waters containing radium isotopes. These waters cause radioactive pollution of natural environment in mining areas. Therefore cleaning of saline waters of radium is very important. Two types of radium-bearing waters were distinguished - one type (type A) containing radium and barium ions, but no sulphates and another one (type B) in which radium and sulphate ions are present but no barium. A very efficient and inexpensive method of purification of saline waters of Ba2+ and Ra2+ ions was developed and implemented in two coal mines. As a result of the used technology, based on application of phosphogypsum as a cleaning agent, a significant decrease of radium discharge was achieved - daily of about 120 MBq of 226Ra and 80 MBq of 228 Ra. Another type of radium waters does not contain barium ions, but does contain sulphate ions SO42-. There is no carrier for co-precipitation of radium so radium is transported with discharged waters to main rivers. Different method of purification from radium must be applied for such waters. Laboratory and field experiments were performed, and a cleaning method was chosen. For purification of saline waters - waste products from other industrial processes are applied. The method of purification has been applied in full technical scale in coal mine with very good results - of about 6 m3/min of radium-bearing water was cleaned. This whole process takes place in underground old workings without any contact of mining crew with radioactive deposits, which are produced during the process. As a result the radium amount released to the natural environment was significantly diminished - approximately of about 90 MBq of 226Ra and 150 MBq od 228Ra per day. (author)