A review on cyclic CO2 capture performance of calcium⁃based industrial solid waste

With the growth of energy demand and surging exploitation of fossil fuels such as coal， petroleum， and nat⁃ ural gas， human⁃induced CO2 emissions have been elevating continuously. How to control CO2 emissions and slow down the rate of global warming is a big challenge. With the advantages of low cost， simple process， and high ef⁃ ficiency， a calcium looping technology achieves CO2 capture by using the cyclic carbonation / calcination reactions of CaO， which is currently considered to be one of the most promising technologies for a large⁃scale CO2 capture. Lots of calcium⁃based industrial solid wastes are produced in China annually. Improper disposal ways such as landfill and accumulation in the open⁃air cause serious damage to the environment and human health. Using some calcium⁃based industrial solid wastes as CO2 sorbents in the calcium looping process can not only realize the utilization of wastes and save the limestone resource， but also reduce the cost of CO2 capture. In this study， the current status of research pro⁃ gress on the CO2 capture by calcium⁃based industrial solid wastes was reviewed. The CO2 capture performance of calci⁃ um⁃based industrial solid wastes such as carbide slag， smelting slag (steel slag and blast furnace slag)， lime mud， etc. was summarized. Coal fly ash and bauxite tailings could be used as additives to improve the CO2 capture perform⁃ ance of calcium⁃based materials. Compared with limestone， carbide slag， smelting slag after acid leaching and lime mud showed a higher cyclic stability in the calcium looping process. Many methods to improve the CO2 cap⁃ ture capacities of calcium⁃based industrial solid wastes were highlighted， involving chemical modification， addition of support/additive， and granulation. Calcium aluminates (Ca2Al2O6， Ca12Al14O33， etc.) and MgO were efficient sup⁃ ports， which were promising for industrial applications. In addition， some future research directions for the CO2 cap⁃ ture by calcium⁃based industrial solid wastes were prospected.