The spiral classifier is mainly used for mineral separation, preliminary classification and inspection classification in the ore grinding loop of the gravel plants, together with desliming and dewatering in the sand-washing operation. The spiral classifiers can be divided into single-spiral and double-spiral upon quantity of spirals, and into high-weir type and sinking type upon the depth of the spiral blade into the overflow surface. This high-weir type spiral classifier is used to classify ore with the overflow particle size of 0.83-0.15mm,while as to the sinking type, for ore with the overflow particle size of 0.15mm-0.07mm