Reactivity and Valorization of Products Issued from Carbonation of Saline Waste Solution

International audienceThe valorization of precipitated carbonates is envisaged for industrial gases treatment in order to avoid waste disposal in landfills. In this paper, the valorization focuses on the desulfurization of fumes by carbonate materials through the semi-wet way. Three carbonated materials are tested: two industrial residues and a limestone of reference. Their composition and size distribution are comparable. Infrared spectroscopy and electron microscopy are used to identify the evolution of mineral and surface composition. Multi-scale study highlights different behaviors between carbonate samples. Laboratory dissolution tests reveal that two industrial residues were clearly more soluble and have a final dissolution degree >= 90 %. The same carbonate materials were then tested at pilot scale. The unit can treat around 1,000-2,000 m(3)/h of industrial fumes enriched in SO2 in semi-wet desulfurization process. Injection of H2O was tested at constant temperature and Ca/S ratios to optimize the process. Origin of CaCO3 particles and hydration properties appear as the main factors controlling desulfurization efficiency. Calcium carbonates precipitated in brines show higher efficiency in SO2 conversion rate (40-70 %) in comparison with other carbonate materials in semi-wet way, i.e. limestone or leached wastes (25-35 %). The combination of high dissolution rate of CaCO3 particles with surface hydration appears as responsible for this performance