Geochemical modeling is a computational chemistry technique that facilitates the understanding of underlying mechanisms of chemical reactions, a priori or a posteriori. This is very useful for research on waste valorization (turning residual materials in valuable products), carbon sequestration (e.g. via mineralization) and environmental remediation (e.g. removal of soluble contaminants from the environment or stabilization of contaminated solids). In this work, several case studies will be presented whereby the geochemical modeling software Visual MINTEQ (ver. 3.0 and 3.1, KTH) was use to aid research on the aforementioned topics. The case studies are a result of research conducted by the authors under the project Sustainable Materialization of Residues from Thermal Processes into Products (SMaRT-Pro2) at the KU Leuven (Belgium) over a period of five years. One application of modeling was to discern precipitation from adsorption mechanism of heavy metals and metalloids onto zeolitic sorbents. Another was to predict the solubility of alkali earth metals from minerals in carbonic acid solution as a function of pressures and temperatures used in accelerated carbonation processes. Modeling also enabled comparison between mineralogical characterization and pH measurement of carbonation products, to understand the formation of different carbonates under different processing conditions, including the use of polymorph altering additives. Most recently we utilized geochemical modeling to better understand the purification mechanism of altering pH prior to residue-leachate separation during high-purity precipitated calcium carbonate synthesis from ironmaking slag. The one aspect of geochemical modeling that still requires development is that of databases dedicated to synthetic/industrial minerals, which are rare in nature but common in waste materials. The availability of such data is crucial for increasing confidence in the a priori predictability of carbonation/waste treatment processes.

Geochemical modeling applied to research on waste valorization, carbon sequestration and environmental remediation: A review of SMaRT-Pro2 cases

251st National Meeting (2016)

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