Selenium concentrations in coals and fly ashes from coal fired thermoelectric power plants in Bulgaria

Abstract

The study present new data regarding concentration and distribution of Se in feed coals and fly ashes from seven Bulgarian coal fired thermoelectric power plant (TPPs). The investigation was performed on feed coals and fly ashes from the following TPPs – Maritza East 2, Maritza East 3, Maritza 3, Republika, Bobov Dol, Varna and Russe. Bulk fly ash from Maritza East 2 and Maritza East 3 TPPs and fly ash samples from each row of electrostatic precipitators (ESPs) from Republika, Bobov Dol, Varna and Russe TPPs were collected. Feed coals were also sampled from each TPPs. In order to determine Se concentration more precisely the samples were pre-treated before applying ICP-MS. As a result of the conducted research, the following regularities were established. Elevated amount of Se has been found in the lignite burned in Maritza East 2 and 3 TPPs, while in the bituminous coal burned in Varna and Russe TPPs Se is within the average and below average Se content. The low content of Se in fly ashes from almost all TPPs was observed, except Maritsa 3 TPP, where Se is from 4 to 7 times higher than Clarke value. It was found that the highest concentration of Se is in the finest fly ash fraction.