Transformation of calcium carbonate intermediate generated by reaction between CaCl_2 and Na_2CO_3 solutions and agglomeration of calcite in the intermediate slurry

摘要

Precipitation of calcite was studied by addition of sodium chloride crystal into the calcium carbonate intermediate slurry in a batch crystallizer. In this system rhombohedral calcite dominantly precipitated from 293 to 328K. The number of precipitated calcite decreased against elapsed time in the initial reaction step, and then converged to the different value in later operation period, affected by operation temperature. Small calcite just after transformed is supposed to agglomerate easily, and agglomeration of calcite was considered to be affected by the amount of intermediate in the reacting slurry.