Effect of Impurities on the Decarbonization of Calcium Carbonate Using Aqueous Sodium Hydroxide.

Decarbonizing calcium carbonate (CaCO) is a crucial step for a wide range of major industrial processes and materials, including Portland cement (PC) production. Apart from the carbon footprint linked to fuel combustion, the process CO embodied within CaCO represents the main concern for the sustainability of production. Our recent works demonstrated that it is possible to avoid both the fuel and process CO by reacting CaCO with aqueous NaOH and obtain Ca(OH) and NaCO·HO ( = 0 and 1). This present study provides a further understanding of the process by testing different raw calcareous sources. A high decarbonization (∼80%) of CaCO was achieved for silica-rich chalk, whereas a lower extent was obtained (∼50%) for limestone. To understand the difference in their reaction behavior, the effect of impurities was studied. The effects of the major impurities (Si, Al, and Fe) were found to be marginal, which is advantageous to process industrial grade materials, while the morphology of the raw materials presents a significant impact. The applicability of our decarbonization technology was also demonstrated on magnesite (MgCO).