Employing a step-wise titration method under semi-slow reaction regime for evaluating the reactivity of limestone and dolomite in acidic environment

Cataldo De Blasio, Claudio Carletti, Andreas Lundell, Ville-Valtteri Visuri, Tommi Kokkonen, Tapio Westerlund, Timo Fabritius, Mika Järvinen

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    7 Citations (Scopus)

    Abstract

    Carbonate rocks are commonly utilized in Wet Flue Gas Desulfurization, WFGD, because of their capability to release calcium ions and precipitate as solid gypsum in an acidic environment. Studies on the reactivity of carbonate rocks and dissolution models can be employed for optimizing the WFGD process. The correct evaluation of limestone reactivity is therefore necessary for the design of the WFGD scrubbing process and for plant operation. In this study, after statistical considerations on evaluating the sample size threshold, a mathematical model and a detailed procedure are given for the estimation of the reaction rate constant and mass transfer coefficient.

    Results are reported from testing limestone and dolomite samples with different formation periods and geological backgrounds. Samples were tested in a Batch Stirred Tank Reactor (BSTR) with a stepwise titration method using hydrochloric acid and non-steady state conditions. In the experiments particles were shown to be completely immersed in a defined viscous sub-layer. A parametric evaluation for the reaction rate was performed at each titration step using an implemented software procedure that handles hundreds of pH values and more than fifty particle size ranges. The experimental data were accurately fitted to the model. The second order model for dolomite and limestone samples accounts for both mass transfer and reaction rate terms, yielding values for the mass transfer coefficients that are congruent with values estimated by fluid-dynamics inspection.

    Original languageUndefined/Unknown
    Pages (from-to)43–58
    Number of pages16
    JournalMinerals Engineering
    Volume86
    DOIs
    Publication statusPublished - 2016
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Gas desulfurization
    • Limestone reactivity
    • Transport phenomena

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