Behaviour of elements and minerals during preparation and combustion of the Pernik coal, Bulgaria

The chemical and mineral composition, including major (Al, Ca, Fe, K, Mg, S, Si, Ti), minor (Na, P) and trace (Br, Cl, Co, Cr, Cu, Li, Mn, Ni, Pb, Rb, Sr, Zn) elements and different minerals, of the Pernik subbituminous coals and their preparation and combustion solid waste products were studied. Feed coals, upgraded coals (high-grade and low-grade coals) and their waste products, namely coal slimes and host rocks generated from the Pernik coal preparation plant, as well as combustion waste products such as bottom ashes, fly ashes and lagooned ashes resulted from the Republica coal-fired thermoelectric power station were characterized. The occurrence and behaviour (partitioning, volatilization, condensation, capture and retention) of the above-mentioned elements and various minerals during coal preparation and combustion are described. The results indicate some technological problems and possible environmental pollution of the air, water, soil and vegetation with certain elements in the areas surrounding both thermoelectric power station and coal preparation plant.