Calcium carbonate granulation in a fluidized-bed reactor: Kinetic, parametric and granule characterization analyses

The granulation of calcium carbonate (CaCO₃) exhibited high industrial demand due to its wider application and importance in cement, paper, glass and steel manufacturing. This paper investigated the granulation kinetics of CaCO₃ through the fluidized-bed homogeneous granulation (FBHG) process during the homogenous nucleation stage. The CaOH solution was used as source of Ca²⁺ reactant, while K₂CO₃ solution as source of CO₃²⁻ precipitant. The mechanism followed the pseudo-second order kinetics. The calcium cation attracts the carbonate anion to form CaCO₃ through a double displacement chemical reaction. The calcium-is-to-carbonate molar ratio ([Ca²⁺]/[CO₃²⁻]) was varied into 1.25 to 2.50, with constant values of pH = 10 ± 0.2, influent carbonate concentration = 10 mM and total influx flow rate = 60 mL min⁻¹. The ideal [Ca²⁺]/[CO₃²⁻] condition was found to be at 1.50 that means the precipitation of CaCO₃ grew and stayed inside the reactor. At the same condition, granules of diameter size of 1 mm to 2 mm were collected with a subrounded shape and smooth surface as shown by its surface morphology. The characterization analysis also verified the high purity of CaCO₃-aragonite granules precipitated through the FBHG process.