Crystal growth rate of calcite in a constant-composition environment

摘要

The growth kinetics of calcite crystal was studied in a fluidized-bed crystallizer using a constant-composition method. Several operation variables were investigated, including supersaturation, pH value, activity ratio, ionic strength and superficial velocity. These factors except superficial velocity are significant as far as the influence on the calcite growth rate is concerned in the range of relative supersaturation (sigma) between 0.5 and 1.5, pH value between 8.5 and 9.5, ionic strength between 0.004 M and 0.016 M; however, the calcite growth rate remains constant for the ionic strength varying from 0.016 M to 0.028 M. The crystal growth rates were calculated from the consumption rate of titration volume, contrast to the decreasing rate of calcium ion used in the pH-stat method. Then the calcite growth rates were compared with those determined by the pH-stat method.