Effects of impurity on crystal growth and nucleation kinetics in an MSMPR crystallizer

An MSMPR crystallizer was used to study the crystallization kinetics of potassium alum in the presence of impurities. Three different types of impurity, including an ionic species (Cr3+), a dispersing agent ((NaPO3)(6)), and an organic dye (Bismarck Brown), were tested. Although various effects of impurities on the crystal growth and nucleation rates were observed, the responses to the addition of impurity for crystal growth and nucleation rates were in the same direction; no matter they were increasing, decreasing, or remaining unchanged. However, under the constraint of constant magma density and retention time, different kinetic behavior, that is, the addition of impurity causes the crystal growth and nucleation rates to respond in an opposite direction, for the same system was concluded.