Utilization of oil shale combustion wastes for PCC production: Quantifying the kinetics of Ca(OH)2 and CaSO4·2H2O dissolution in aqueous systems

• Oil shale ash could be utilized as a low-cost source of lime for PCC production.
• The dissolution mechanisms and kinetics of Ca(OH)2 and CaSO4·2H2O were investigated.
• Reaction rate constants for Ca(OH)2 and CaSO4·2H2O dissolution were determined.
• The kinetic models were implemented within the Aspen Plus simulation platform.

The ash produced during oil shale combustion is classified as waste, however, one could also view it as a low-cost source of lime for the abatement of SO2 and CO2 emissions as well as for the commercial production of precipitated calcium carbonate (PCC)-type filler material. This study focuses on the dissolution mechanisms of the main water-soluble calcium species in oil shale ash–water systems. Reaction models that describe the dissolution of Ca(OH)2 and CaSO4·2H2O in water were developed and the kinetic parameters of the proposed system composed of differential equations were estimated by optimizing the model reproduction of experimental data. The dissolution kinetics of Ca(OH)2 and CaSO4·2H2O were also simulated using the Aspen Plus process modeling platform.