The secondary nucleation kinetics of potassium chloride crystallization from brine at 40℃ is investigated in the suspension density MT range from 51 to 146 g/1 and at agitation speed N 820 r/min and 650 r/min in a 2.5 IMSMPR crystallizer with clear liquor overflow. The power index i in the kinetic equation is independent of both Mr and N

and is 2.9. The power index j is 1. 1 at 820r/min. The coefficient of the kinetics equation is highly sensitive to agitation speed. Too high agitation speed should not be used in crystalli-zers not only for energy saving but also for coarse product. High suspension density and long retention time should be used in industrial crystallizers for high productivity and coarse product size respectively.