Mercury contents in Pernik coals and disposal pond waste products

Mercury contents in two types of Pernik coals and in mixed waste from coal preparation and combustion from a disposal pond were measured using direct mercury analyzer. Pearson correlation coefficients between Hg concentrations and ash content among different types of samples are statistically insignificant, suggesting predominantly organic affinity of Hg. The Hg content of 150 ppb in the fuel for the thermoelectric power station (low grade coal) slightly exceeds the world average for brown coals (100 ppb). Mercury concentrations in the mixed waste are twice lower than those in low grade coal, suggesting that Hg is released into the atmosphere during coal processing. However, coal for indoor heating (high grade coal) is significantly enriched in Hg (average of 392 ppb) and, therefore, its residential use as fuel may release larger amounts of Hg to the atmosphere. Newly formed gypsum from the disposal pond concentrates Hg (221 ppb).