Effects of Ca²⁺ and OH^- Ions on the Process of Calcium Carbonate Synthesis and its Crystallization

Abstract

The effects of ionic concentrations of Ca²⁺ and OH^- ions and crystallinity of Ca(OH)₂ on its carbonation reaction were investigated. The process of carbonation was followed by the measurement of electrical conductivity in slurry. Calcite was produced via an intermediate amorphous product, whose composition was determined to be Ca_1+xCO₃(OH)_2x·yH₂O(x>0.05, y=0.6-0.8) by means of DTA, TGA and CHN analysis. The particles of calcite obtained varied from a dispersed cubic shape to a needle-like or spindle-like condensed shape. This change was ascribed to the decrease in ionic concentration during the crystallization process from the intermediate amorphous phase to calcite.