Abstract: The limestone grits, formerly considered a waste product of the lime slaking process, become economically salvageable after successful fractionation to separate them into three parts: (1) caustic chemicals useful in the kraft pulping process; (2) under-, and over-calcined small limestone particles having an impurity level virtually identical to that of raw limestone; (3) caustic-free large particles containing the majority of residual impurities such as silicon, iron, magnesium, and chromium. The fractionation of limestone grits is economically carried out by a refluxive hydraulic washing system in which the untreated limestone grits from the slaker and first introduced into the open mouth of a vortex washer where they undergo an initial separation in which most of the smaller particles and caustic chemicals are recovered.