Analysis of the Process of Mineral Sequestration of CO2 with the Use of Fluidised Bed Combustion (FBC) Fly Ashes

Abstract

There is a current focus on replacing the generally accepted conventional power generation technologies with more advanced ones that will better protect the natural environment. The need to limit CO2 emissions from power generation plants presents a problem that must be solved in many countries that use coal or lignite as basic fuels. One potential option is mineral sequestration performed using side products of fossil fuel combustion, such as fluidised bed combustion (FBC) fly ashes. Fluidised bed combustion (FBC) lignite fly ashes are characterised by a high storage capacity of 15.7%. Research conducted with the most commonly used method of direct mineral sequestration—CO2 trapping with fluidised bed combustion (FBC) ash in water suspension—has indicated a very high level of carbonation of CO2, reaching 11%. Calcite was the basic product of carbonation. The calcite content increased from 2% to 12% in the suspension subjected to treatment with CO2. Furthermore, CO2 reduced the pH and limited the leaching of impurities, such as Zn, Cu, Pb, Ni, As, Hg, Cd, Cr, Cl, and SO4. The fly ash suspensions subjected to CO2 treatment can be used in industry in the final stage of carbon capture and utilisation (CCU) technology, which will further contribute to the implementation of the circular economy.