This study was undertaken to investigate the effect of initial slurry concentration on the particle shape and particle size distribution of precipitated calcium carbonate by a carbonation process in which CO
2 was blown into aqueous slurries of Ca(OH)
2. The present carbonation process was formulated on the basis of the concept that the rate of Ca(OH)
2 dissolution is balanced with the rate of CO
2 absorption by carbonation reaction in aqueous slurries containing Ca(OH)
2 fine particles. The relationship between reaction completion time and operational conditions was obtained.
The synthesized calcium carbonate powder was pure white calcite crystal and had cubical shape with a median diameter of 0.4-0.6μm. The reaction completion time was directly proportional to the initial concentration of Ca(OH)
2 in slurry. When the initial slurry concentration was increased to above 5.0wt%, the median diameter x
50 increased and the size distribution became narrow. The observed dependence of reaction completion time on the initial slurry concentration and the CO
2 sparging rate could be qualitatively interpreted in terms of the proposed formulation for the carbonation process.
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