Accelerated carbonation of waelz slag: effect of particle size on CO2 sequestration capacity

CAPPAI, GIOVANNA SALVATORICA;DE GIUDICI, GIOVANNI BATTISTA;MEDAS, DANIELA;MILIA, STEFANO;MUNTONI, ALDO;Orrù G;NIEDDU, ALESSIO;PIREDDA, MARTINA

2014-01-01

---

Abstract

The application of accelerated carbonation to sequester CO2 in Waelz slag, a by-product from metallurgical industry, is presented. The main aim of this work was to assess the influence of solid particle size on CO2 sequestration capacity and on reaction kinetics. Accelerated carbonation tests performed on Walez slag ground to below different grain size (4; 2; 1; 0.5; 0.3 and 0.045 mm) according to direct aqueous routes (L/S=0.4 L/kg, PCO2 =5 bar; T=25 °C) indicate that these residues are excellent candidates for engineered carbonation process. Specifically, a CO2 uptake up to 16% was observed for gently grinded materials and achieved 19% when slag was ball milled to below 0.045 mm size. In the latter case, the carbonation process resulted in a different reaction mechanism and better crystallinity of carbonation products.