Improvement of CO₂ Absorption Properties of Limestone Ore by the Addition of Reagent Grade-SiO₂ and Natural Diatomite

Abstract

CO₂ absorption/release properties of limestone mixed with 2.5∼40 mass% reagent grade-SiO₂ powders or natural diatomite have been investigated. XRD analysis of calcined diatomite-mixed limestone revealed the formation of Ca₂SiO₄. However, only CaO and SiO₂ were confirmed in the case of the calcined limestone mixed with reagent grade-SiO₂ powders. Addition of reagent grade-SiO₂ and natural diatomite led to improvement of CO₂ absorption capacity of limestone ore. In the initial absorption process, limestone mixed with 10 mass% reagent grade-SiO₂ showed the highest degree of absorption (67%; 673 K, 21.6 ks). In the case of natural diatomite, CO₂ absorption degree attained maximum (∼55%) at 5 mass% of natural diatomite. Furthermore, the absorption durability of limestone ore was improved by the addition of reagent grade-SiO₂ or natural diatomite. These results indicate that the addition of reagent grade-SiO₂ particles or natural diatomite is an efficient way to improve the absorption properties of natural limestone ore.