Możliwości zastosowania popiołów lotnych ze spalania węgla kamiennego w kotłach wodnych do sekwestracji CO2 na drodze mineralnej karbonatyzacji

CO2 sequestration via mineral carbonation is one of the reduction methods of anthropogenic emission of CO2. It is based on permanent, and at the same time, ecologically safe CO2 bonding through mineral resources or waste. For CO2 bonding there may be used the alkaline mineral waste, f.ex: fly ash, originating from professional power industry plants - the greatest source of anthropogenic emission of CO2 in Poland. In the article there have been presented the results of examination of carbonation extent for ash aqueous suspension, prepared on the basis of fly ash from hard coal combustion. The findings on carbon dioxide absorption through fresh ash aqueous suspension have been shown, as well as the extent of its bonding in the hardened suspensions. On the basis of thermogravimetric analyses supplemented with phase composition examinations with the use of roentgenographic method and microstructure examinations with the use of a scanning microscope. There has been carried out an analysis of the impact of carbon dioxide insertion on the leachability of the ions: Cl-, SO4, As, total Cr, Cd, Cu, Pb, Hg, S (sulphide), on the basis of results of leachability examinations from ash suspension with water before and after CO2 insertion, as well as the influence of carbon dioxide insertion on pH of leachates and the chemical oxygen demand (COD). It was affirmed as the result of thermogravimetric investigations of ash-water suspension without introduction of CO2, content of CaCO3 was 0.75 %, and in suspensions with introduced CO2, content of CaCO3 was 2.27% [24], which confirms that processes of mineral carbonation takes place. Investigations of leachability showed increased concentration of Zn and the content of chlorides and sulfates in suspensions with introduced CO2. Concentration of determined elements in extracts of ash-water suspensions "clean" and with the addition of CO2 fulfilled standards of PN-G-11011. Sequestration of CO2 via mineral carbonation is an interesting option of limitation of anthropogenic emission of CO2. Use of wastes for bonding CO2 seems particularly interesting. In case of Poland, where production of electric and thermal energy in plants of professional energetics is based on coal incineration, the waste which used for bonding CO2 is produced in large quantities fly ash.