CO2 capture by the slag from lignite’s chemical looping gasification using carbide slag

Due to its large amount, solid waste used as an oxygen carrier in chemical looping gasification (CLG) is not generally recycled. In order not to turn solid waste into secondary solid waste, re-resourcing research of the slag from CLG is worth consideration. The slag from lignite's CLG mainly consists of CaCO3, CaO, and small amounts of Ca(OH)2. In order to further purify CaCO3 and to achieve reduction in carbon emissions, the present work proposed the use of slag from lignite's CLG to capture CO2 and obtain purer calcium carbonate. The reaction properties and the reaction mechanism of the slag from CLG for CO2 capture were investigated using thermodynamic simulations, tubular furnace experiments, thermogravimetric experiments and characterizations. After analyses, it was suggested that reaction temperature for CO2 capture using slag from CLG lied within the temperature range of 300 - 800 °C. Reaction mechanism of slag from CLG to capture CO2 was different at different reaction temperatures. When the reaction temperature lied within the range of 300 - 400 °C, and were the main reactions. When the reaction temperature lied within the range of 400 - 800 °C, was the main reaction. The present study provides a method to turn waste into treasure without the need of subsequent recycling during lignite's CLG, and promotes the realization of "International Double Carbon Policy".