On the reactivity of carbonate rocks utilized in wet flue gas desulfurization: modeling the reaction kinetics of solid particles by a step-wise titration method with turbulent conditions

Carbonate rocks are largely utilized in Wet Flue Gas Desulfurization, WFGD, processes because of their capability to release calcium ions in acidic environment and precipitate as solid gypsum. The correct evaluation of limestone reactivity is therefore necessary for FGD wet scrubbing process design and plant operation. Additionally, studies on carbonate rocks reactivity with hydronium ions are advised when acid mine drainage remediation processes are modeled. In the present study results are reported from testing samples with different formation periods and geological background. The project aims to evaluate the reactivity of a wide variety of samples from different regions of the world. Samples were crushed to a size between 60 and 100 meshes and tested in a Batch Stirred Tank Reactor, BSTR, with a stepwise titration method using hydrochloric acid and non-steady state conditions. The temperature of the solution was kept constant at 25°C and the particles in our experiments were shown to be completely immersed in a defined viscous sub-layer. The Particle Size Distribution, PSD, was derived from the distribution of the scattered light energy using the Fraunhofer diffraction theory. A parametric evaluation for the reaction rate has been performed using an implemented software procedure which handles hundreds pH values and more than fifty particle’s size ranges. The experimental data was fitted by the model in a really accurate manner.