Use of selective grinding for upgrading quality of lignites from Greece and for reducing CO2 emissions

Lignite plays a dominant role for energy production in Greece, covering over 30% of the demand for electricity generation. Increased energy demand requires, additionally to alternative energy sources, an increase in energy supply from both old and new deposits. Due to the low quality of mined lignite, methods of upgrading in terms of power plants' efficiency and environmental performance need to be applied. In this work, the technique of Selective Size Reduction (SSR) was investigated for three deposits in North Greece, Amynteon, S. Field and Ahlada, in order to improve lignite quality through reduction of its mineral matter content. The variation of the qualitative characteristics of the grain fractions produced by SSR provided useful information on both the suitability of these fractions for combustion in the power plants of the area and the emissions of greenhouse gases. The results have shown that fractions, which were produced from the first stage of crushing, with recovery between 83% and 95%, had lower ash by 16.5-27% than the raw material and were of acceptable quality for combustion in the power plants of the area. Beneficiated fractions could give energy efficiency between 34% and 36% and a reduction in CO2 emissions up to 29%, originated from the decomposition of the carbonate minerals, contained in the mined lignite. As a result, the cost for buying CO2 certificates could be lowered up to 3euro/MWh.