Determination of Mass Transfer Coefficients for Crystal Growth of Nitrate Salts

In this paper, the crystal growth of sodium nitrate and potassium nitrate from aqueous solutions, in a perfectly stirred batch crystallizer, has been studied considering the effect of temperature, supersaturation degree, and the size of seed crystal growth rate. The mass transfer coefficients obtained correlated with Re, Sc and NL dimensionaless numbers. Supersaturation curve determination using a 0.5 mW He-Ne laser, connected to an automated data acquisition system, was the first stage of the study. The supersaturation and saturation curves were closely parallel with average DT value of 4.1 and 6.8 °C for KNO3 and NaNO3 respectively. For the growth kinetics order, unit values were found for both salts, with diffusion as a controlling stage.